A descriptive guide to the Museum of Practical Geology, with notices of the Geological Survey of the United Kingdom, The Royal School of Mines, and the Mining Record Office.

By Robert Hunt, F.R.S., Keeper of Mining Records, and F. W. Rudler, Assistant Curator.

Third Edition.

Revised and partly re-written.

London: Printed By George E. Eyre and William Spottiswoode, Printers To The Queen's Most Excellent Majesty. For Her Majesty's Stationery Office. 1867. Price Sixpence.

Notice

In addition to the detailed catalogues which my associates the Lecturers have prepared to illustrate the various departments of the Museum of Practical Geology, a compendious guide to explain its contents in a popular manner, is wanted for the use of the greater portion of the visitors.

Having induced Mr. Robert Hunt, the Keeper of Mining Records in this establishment, to undertake the task, I trust the work he has produced will be found as instructive and useful as the excellent little Guides to the Exhibitions of 1851 and of 1862 of which he was the author.

The first and second Editions of 5,000 copies each having been sold, the work has been carefully revised by Mr. F. W. Rudler, the assistant curator, so as to illustrate the present condition of the Museum.

Roderick I. Murchison, Director. May 1867.

Introduction

THE MUSEUM of PRACTICAL GEOLOGY is intended to exhibit the rocks, minerals, and organic remains, illustrating the maps and sections of the GEOLOGICAL SURVEY OF THE UNITED KINGDOM : also to exemplify the applications of the Mineral productions of these Islands to purposes of use and ornament :—to show, in fact, the results which have been obtained from the efforts of thought and industry brought to bear upon the raw materials with which Nature has supplied us.

The collection, therefore, divides itself into two principal groups.

The natural materials—Geological and Mineralogical—which may be studied as to their lithological character, their geological order, or their mineralogical constitution.

The artificial productions, exhibiting the results of human labour aided by the discoveries of science.

There are also three secondary, but important divisions.

The mechanical appliances, which are used in working the raw materials.

The historical specimens, which have been added with the view of preserving, in juxtaposition with modern manufactures, the productions of her ages and countries for purposes of comparison.

The foreign and colonial Minerals imported into this country in the natural state.

There are some other objects, valuable from their educational character, constituting a miscellaneous group, which cannot be brought within any of the above divisions. These are geological and mining models showing the various phenomena which occur in those districts which have been explored by man in his search for mineral treasure.

Such are the objects of the Museum of Practical Geology, which originated from a representation submitted in July 1835, by Sir Henry Thomas De la Beche, to the Chancellor of the Exchequer. The Geological Survey had recently been commenced in connection with the Ordnance Survey of the United Kingdom; and it was suggested that means therefore existed of collecting "Specimens of the Applications of Geology to the useful Purposes of Life." The importance of a Museum, which should fairly illustrate the mineral productions of the country, and show their commercial value, was at once recognized. The suggestion of Sir Henry De la Beche received the approval of the Government, and he was authorized to proceed in the development of his idea.

In 1837, Lord Duncannon, Chief Commissioner of Woods and Forests, allotted apartments in No. 6, Craig's Court, to receive the nucleus, around which has gathered the present extensive collection. The MUSEUM OF ECONOMIC GEOLOGY, as it was first named (now the MUSEUM OF PRACTICAL GEOLOGY) was placed under the direction of its originator, and within a short period the collection became so valuable and important, that it was thought necessary to appoint a curator, and accordingly in 1839 Mr. Richard Phillips, F.R.S., was chosen for the office. Advantage was taken of Mr. Phillips' abilities as a chemist, to unite analytical investigations with his duties as curator. A laboratory was attached to the establishment; analyses of minerals, rocks, and soils were made, and instruction was given, to a limited number of students, in chemistry and metallurgy. From this originated the Rovia, Sermon OF Mums (formerly edited the GOVERNMENT SCHOOL OF MINES), united with this establishment, in which such branches of science are taught as have an especial bearing upon our mining and metallurgical industries. The office of curator and chemist was retained by Mr. Richard Phillips until his death, which occurred upon the day on which the present building was opened.

As the Geological Survey progressed, the Museum was rapidly extended. The original idea of a collection so practical in its character, and so peculiarly adapted to the wants of a great commercial and manufacturing community, being felt to be a correct and useful one, presents flowed in from persons interested in those particular branches of industry which it was intended to illustrate.

In August 1838, a representation was made to the Government by a Committee of the British Association for the Advancement. of Science, to the effect that with a view to prevent the loss of life and of property which will inevitably ensue from the want of accurate Mining Records, it is a matter of national importance that a depository should be established for the collection and preservation of such Mining Records of subterranean operations in collieries and other mining districts." The result of this was that an office was established, under the title of the MINING RECORD OFFICE, and Mr. T. B. Jordan was appointed the Keeper of Mining Records in 1839, which office he held until 1845, when he was succeeded by the author of this Descriptive Guide.

In 1845 the Geological was separated from the Ordnance Survey, and placed, with the Museum of Practical Geology, under the Department of Woods and Forests. The necessity for, fitting accommodation became so pressing that, with as little delay as possible, the present building was erected by Mr. J. Pennethorne, for the Office of Woods and Works, the Chief Commissioner at that time beincr₆ the Earl of Lincoln (the late Duke of Newcastle). It was opened to the public in May 1851, by His Royal Highness the late Prince Consort, and in November in the same year Sir Henry De la Beche delivered his inaugural discourse at the opening of the School of Mines.

The progress of the Geological Survey—now under the guidance of Sir Roderick Impey Murchison, Bart., the present Director-General —is shown by the large map hanging upon the western wall of the hall. This map will serve to direct the inquirer as to the positions in which the building stones, and other minerals described, are found; hence it will be frequently referred to. The Geological Survey has, in its progress, been constantly adding to the stores of the Museum of' Practical Geology, and, it is now especially rich in those illustrations which show us, the progress of life upon this globe, and mark its great mutations. Its Palæontological collections, whether regarded as objects of scientific interest, or as guides to the searcher for mineral treasures, are of the highest value. The Mineral Groups, either in their earthy or the metalliferous divisions, have a large commercial interest, and must convey to all attentive minds an instructive lesson.

It is to guide the public in their examination of those specimens, to, inform them of their natural peculiarities,—and some of the methods by which they are rendered practically useful, that the present work has been undertaken. This volume must not be mistaken for a Catalogue of the Museum; it is a Descriptive Guide to the various groups of specimens which it contains. Hence it is that, although sufficient indications are given of the position in which the examples described aro to be found,—a system of grouping the objects under general headings has, in most oases, been adopted as the easiest means of communicating the largest amount of information within a limited space.

As considerable interest must eventually attach itself to every circumstance connected with the first experiment of a popular educational character made by the British Government, it has been thought desirable to put on record some account of the opening of this Institution.

On Monday, May 14, 1851, the Museum of Practical Geology was formally opened by His Royal Highness the late Prince Consort, in the presence of a large circle of the leading members of the world of science, and of the aristocracy. The Prince Consort having taken the chair, on the principal floor, Sir Henry De la Beche, as Director of the establishment, approached His Royal Highness and read the following address :

To His Royal Highness the Prince Consort, D.C.L., F.R.S., &c.

"May it please your Royal Highness,

We, the officers of the Museum of Practical Geology, deeply sensible, in common with our fellow countrymen, of the earnest and increasing desire of your Royal Highness to patronize and aid all that may advance the happiness and promote the progress of our nation, and not only of this, but also of other lands, as is abundantly proved by the untiring exertions which have brought so vast a design as an Exhibition of Industry of all Nations to that successfulissue which will make it memorable in the annals of our country, request permission to express our respectful thanks for this establishment having been considered one to be included among those which have public advantage and progress for their objects, and as such deemed worthy this day of the preience of your Royal Highness. The Museum of Practical Geology was founded, in 1835, in consequence of its having become evident, during the earlier progress. of the Geological Survey of Great Britain, that numerous opportunities presented themselves, which it was not desirable to forego, for illustrating the applications of geology to the useful purposes of life. It was considered that collections should be made with that object, and be arranged with every reference to instruction, so that those interested might be enabled to judge how far our known mineral wealth might be rendered available for any undertaking they might be required to direct, or were anxious to promote, for the good or ornament of their country.

As geological surveys necessarily include information which, if rightly interpreted, is of great value to agriculture, care was also taken to render the museum useful in that direction, so that, - whether the districts examined were agricultural or mining, they should alike receive attention. To promote a knowledge of the properties of soils, as well as to effect an examination of the various ores of the metals, and of other mineral products of importance to the possessor of mineral property, the miner, the engineer, the architect, and of those interested in arts and manufactures generally, a laboratory in connection with the museum became necessary. The laboratory has frequently proved useful to the departments of the Government. We may point to the inqitiry for the Admiralty into the coals of this country best suited for our steam navy, the third and final report on which has just been laid before the Parliament, as among-thelas4-and probably not the least; important investigations undertaken for the Government at this establishment. Though much has been accomplished far our collections by the progress of the Geological Survey, much also has been effected by the kind consideration of the various classes of the public interested is our advance, and, in consequence, presents to a large amount have swollen the collections to their present state. Many of these presents have been alike extensive and valuable, and we feel no little pride in including your Royal Highness among those who have aided us with donations, as well at a time when the museum was in its infancy, located in a comparatively obscure building, as now, when, in a more appropriate structure, the various objects for which it was established can be effectively carried out. The museum had been so far developed in 1840 that, in consequence of a representation of a committee of the Association for the Advancement of Science, the Government directed an Office of Mining Records to be attached to it; and it is hoped that thereby, as was stated by that committee, many of those great losses of life and of capital which have been sustained from want of such records may, to a great extent, be avoided. A valuable collection of such records has been already formed; and we have also, in this department, to acknowledge the aid which your Royal Highness has afforded us, as Lord Warden of the Stannaries, by permitting copies of the mining plans and sections of the Duchy of Cornwall to be taken for this office. It is but right, also to state, that from the mining interests generally we have experienced every encouragement, with regard to our mining records, so that we may hope, at no distant date, to have collected an amount of practical information on this head especially valuable as regards old workings and mines which have been abandoned.

Though many years since, in 1839, the Government sanctioned lectures in connection with the museum on analytical chemistry, agricultural chemistry, metallurgy, mining and mineralogy, the want of proper accommodation has, until the present time, prevented their delivery. Now, however, that a theatre for them has been provided, it has been deemed expedient to extend these lectures, so as to embrace instruction of a character resembling that given in Foreign Schools of Mines, and which, while it should be adjusted to the wants of this country, should also have reference to the mineral wealth of the empire at large.

Several memorials from important mining districts have been presented to the Government, to afford facilities at this establishment for instruction available for the mining interests, one of so much magnitude in this country; the value of the mineral products of Great Britain and Ireland being now estimated at 25,000,000/.^[1] per annum, the various products taken as nearly as possible in their first state. It has been further estimated by competent foreign writers that the annual value of the mineral substances raised in the British islands is equal to about four-ninths of that of all Europe, including these islands.

To your Royal Highness it would be needless to point out the bearing of the Mining Schools of France, Saxony, Russia, and Austria upon the mineral resources of those countries, the useless expenditure they prevent, and the real productiveness they promote. To those whose duty it is to pass among our mining districts, it is often matter of regret to find many a powerful mind struggling with a want of knowledge of that which others have accomplished, or may be now doing. Great as the achievements of uninstructed men have sometimes been in such districts, they would have been still greater, and the instances would have been more multiplied, had better opportunities been afforded.

While it is proposed to receive pupils by regular courses of study,—to teach by means of lectures,—experimental researches in the laboratory,—and also by the aid of the Geological Survey in the field, the collections of the museum will be gratuitously open to public view. Your Royal Highness will have seen, by inspection of these collections, that they are alike scientific and practical. We feel that in this we are not likely to have erred in the opinion of those who believe, as we do, that the greater the amount of science, the greater will be the amount of its application. In addressing your Royal Highness on this subject, we know that we are addressing a Prince who feels a deep interest in it, and who justly appreciates its general bearing.

That the honoured consort of our beloved Queen may long continue to exercise that beneficial influence which his enlarged views and exalted station command, is the earnest and sincere hope of the officers of this establishment."

Sir Henry de la Beche, having concluded reading the address, presented it to the Prince.

His Royal Highness acknowledged it in the following terms :—

"In thanking you for the address which you have just read to me, I would also express the sincere gratification with which I witness the opening,—in a form more likely to make it generally and practically useful,—of an institution the progress of which I have long watched with much interest, and the want of which has been long felt in this country. I rejoice in the proof thus afforded of the general and still increasing interest taken in scientific pursuits; while science herself, by the subdivision into the various and distinct fields of her study, aims daily more and more at the attainment of useful and practical results. In this view it is impossible to estimate too highly the advantages to be derived from an institution like this, intended to direct the researches of science and to apply their results to the development of the immense mineral riches granted by the bounty of Providence to our isles and their numerous colonial dependencies. It will always give me the greatest pleasure to hear of, and, as far as I am able, to contribute to, the continued success of the Museum of Practical Geology."

The Building

The edifice itself must be regarded as one of the illustrations of the main objects in view. It was designed by Mr. James Pennethorne, who, co-operating with Sir Henry De la Beche, endeavoured to make it, in all particulars, an illustration of the applications of Geology.

The Piccadilly front of the Museum is constructed of Anston (Yorkshire) Dolomite or magnesian limestone, of the same kind as that employed for the exterior of the new Houses of Parliament. The Jermyn Street front is composed partly of the same stone, and partly of Suffolk bricks.

The steps at the entrance are of the red granite of Peterhead, and at the doorway is a slab of slate from the Penrhyn quarries of North Wales. The pavement and steps leading into the hall are of Portland stone; the base of the sides of the vestibule is of Irish granite, the ripper portion of polished Derbyshire alabaster; and the pilasters on either side at the heads of the steps from the vestibule of the grey Peterhead granite. As all these stones have their representatives in the hall, particulars respecting them will be found under their special heads.

The Vestibule and Hall

These are devoted to the exhibition of the building and ornamental stones of the United Kingdom, with such miscellaneous articles as could not be conveniently placed on any other floor.

The Lecture Theatres

The large theatre is situated immediately north of, and is entered from, the Hall. It is constructed for seating 500 persons, but on many occasions, especially when lectures are delivered to the working men, considerably more than that number have been accommodated. In this theatre most of the lectures to the several classes of the ROYAL SCHOOL of MINES are delivered; but a smaller room on the upper floor of the building is especially devoted to certain classes.

The session commences in October and terminates about the end of June. A prospectus and information may be obtained on application.

The Library

Beyond the theatre in the Piccadilly front of the building is the Library of the institution, containing upwards of 15,000 volumes of books devoted to the sciences taught in the school. These are available for the use of the students of the School of Mines, and, — upon special application, stating the object in view, — the books can be consulted by other enquirers. As most of the important periodicals relating to science published in this country, on the continent, and in America, are regularly received, and also the new publications bearing on the sciences taught, the number of books very rapidly increases.

The Principal Floor of the Museum

In this department will be found the collection of metalliferous minerals, with illustrations of metallurgy; the earthy minerals and their useful applications, exemplifications of the conditions under which metalliferous ores occur in nature. In fact all the principal objects which have a relation to Practical Geology will be found in this important division of the Museum.

The Model Rooms

At the northern end of the principal floor aro two rooms which, with a small supplementary room on the lower gallery, are devoted to mining and metallurgical models. Several, however, are distributed around the principal floor of the Museum.

A Descriptive Catalogue of the Models can be obtained in the building.

The Galleries

The lower and the upper galleries are devoted to scientific geology. The fossil collections will be found, commencing on the western side of the lower gallery, with the earliest forms of organization, and proceeding in an ascending order to the upper one. A Catalogue of the collection of Fossils, with an explanatory Introduction by Professor Huxley, is published. In the recesses of the upper gallery will be found a collection of British Rock specimens, of which a special catalogue is published.

The Geological Survey, and the Mining Record Offices

The Geological Survey, and the Mining Record Offices will be found at the southern end of the upper gallery.

The chemical and metallurgical laboratories

The chemical studies, under the charge of Dr. Frankland, are conducted at the College of Chemistry in Oxford Street. The two Laboratories in the building, one on the basement, and the other at the northern end of the upper gallery, are devoted to Metallurgy under the direction of Dr. Percy.

The Collections

The Hall

Although it is foreign to the general purpose of this guide-book to insert special catalogues of any of the collections exhibited, it, has yet been considered desirable to introduce the following inventory of the objects in the Hall, since this department—unlike most other sections of the museum—is not provided with a catalogue of its own. In the arrangement of this inventory no system of classification has been attempted, but, consulting solely the convenience of the visitor, the objects have been numbered in that order in which it is believed they will be found with the least possible difficulty. Commencing on the right hand side of the entrance, the numbers first make the entire circuit of the walls, and are thence continued to the objects in the general area, passing from the western side along the northern end to the eastern side, and finally around the central pavement, terminating with No. 221, at the foot of the left hand or western staircase.

Appended, in most cases, to each item in the inventory is a reference indicating the page of this guide-book at which a general description of the object under examination may be found; and it is hoped that with this system of reference—aided, if necessary, by the general index at the end—no difficulty whatever will be experienced in immediately finding the information required respecting any object in this department.

Inventory of objects in The Hall

No.

1. Column of porphyritic granite; Galway, Ireland (p. 18).

2. Column of marble; Matlock, Derbyshire (p. 22). Supporting No. 3.

3. Vase in Cornish Kaolin or China-clay (p. 49).

4. Column of marble, Chudleigh, Devon (p. 24).

5. Column of marble; Babbacombe, Devon (p. 24).

6. Large crystal of Quartz (p. 141); at foot of Case III.

7. Inlaid slab of steatite and serpentine; Lizard district, Cornwall (p. 21).

8. Ornamental pedestal of granite; Fremator quarries, Devon (p. 18). Supporting No. 9. Presented by Wagstaffe & Co.

9. Cast in plaster of Paris of a large Greek vase obtained at Naples by Sir Woodbine Parish, K.C.H., by whom it was presented (p. 34).

10. Portion of an inlaid table-top of Derbyshire and Staffordshire marbles, made and presented by the late Mr. Milne, Ashford, Derbyshire (p. 24).

11. Column of marble, Lligwy, Anglesey (p. 25).

12. Spiral column of Penrhyn slate (p. 27).

13. Polished block of Tiree marble; Hebrides (p. 26).

14. Slab of black Derbyshire marble inlaid with "V. R." in red marble (p. 24).

15. Casts of weapons and armour in bronzed plaster of Paris, from Paris (p. 34). On the wall above.

16. Column of breccia marble; Isle of Man (p. 25). Supporting No. 17.

17. Bust in terra-cotta (p. 58).

18, 19, & 20. Three patent iron tubes, one of which is 13 ft. 41 ins. in length, and 7 ins. in diameter. Manufactured by Messrs. Selby and Johns, Smethwick; and presented from the Great Exhibition, 1851, by Messrs. Bird & Co. (p. 112).

21. Column of marble; Allport, Derbyshire (p. 22). Supporting No. 22.

22. Statuette in terra-cotta inscribed "Mich. Rysbrack, 1753" (p. 58).

23. Slab of limestone, exhibiting ripple marks; from the Middle Purbeck beds, Durdlestone bay, Swanage (p. 30).

24. Column of Marble; Allport, Derbyshire (p. 22). Supporting No. 25.

25. Vase in terra-cotta (p. 58).

26. Bar of the best Staffordshire iron, measuring 20 ft. 1 in. in length, and 7 ins. in diameter; and weighing 1 ton, 2 cwt., 3 qrs., 12 lbs. Rolled at the works of Messrs. J. Bagnall & Sons, West Bromwich, and presented from the Great Exhibition, 1851, by Messrs. Bird & Co. (p. 112).

N.B.-The screens which ornament the wall on this side are described at p. 16.

27. Large mass of purple copper ore, or Buntkupfererz, from near Disco, Greenland (p. 75). Presented by Sir W. Trevelyan, Bt., and Messrs. Robinson and Westenholz. Beneath Case III.

28. Boulder of hematite, or red-iron ore, from the base of the new red sandstone, Porlock, Somersetehiro (p. 102). Presented by the late Mr. E. Rogers. Beneath Case III.

29, and 30. Polished slabs of granite; Killiney, Ireland (p. 18).

31. Mass of red oxide of copper, from the Burra Burrs mines, South Australia (p.95). Presented by the directors. Beneath Case III.

32. Column of Derbyshire marble (p. 22).

33. Pilaster of red Peterhead granite (p. 17).

34. Column of marble; Nether Haddon, Derbyshire (p. 22).

35. Polished slab of serpentinous marble; Ballinahinch, Galway (p. 22).

36. Pedestal of red Peterhead granite (p. 17). Supporting No. 37.

37. Copy of the Giustiniani Minerva, sculptured in Huddlestone dolomite by Mr. C. H. Smith (p.31). The stone presented by Messrs. W. & J. Freeman.

38. Polished slab of encrinital marble; Derbyshire (p. 23).

39. Column of marble; Monyash, Derbyshire (p. 22).

40. Pilaster of serpentinous marble; Ballinahinch, Galway (p. 22).

41. Column of black marble; Galway, Ireland (p. 25).

42. Portions of basaltic columns, from the Giant a Causeway, Ireland (p. 38). Presented by Mr. J. Brown.

43. Column of encrinital marble; Ashford, Derbyshire (p. 23).

44. Pilaster of marble; Babbacombe, Devon (p. 24).

45. Cube of calamine, or carbonate of zinc, from the Vieille Montagne Company's works, near Aix-la-Chapelle (p. 86). Presented by the Company, from the Great Exhibition, 1851. Beneath Case IX.

46. Large 6-inch bar of Staffordshire iron, rolled by Messrs. Bagnall and Sons, West Bromwich; and presented, from the Great Exhibition, 1851, by Messrs. Bird & Co. (p. 112). Beneath Case IX.

47. Slab of fossiliferons Portland stone, from Tishury, Wilts (p.29). Beneath Case IX., western side.

48. Pilaster of Clonony marble; King's Co. Ireland (p. 25).

49. Portion of a large sigillaria from the coal measures of South Staffordshire (p. 152). Presented by Samuel Blackwell, Esq.

50. Large block of cannel coal from Haigh, near Wigan, Lancashire (p.135). Presented, from the International Exhibition, 1862, by the Earl of Crawford and Balcarres.

51. Portions of large fossil plants, from the coal measures of Sydney, Cape Breton, British North America. Presented by the late Earl of Dundonald, G.C.B.

52. Specimen of Syringodeadron Boghalease, from Boghall, near Cresswell, Northumberland. Figured in Sternberg's "Flora der Vorwelt," pl. X.XXVII., fig. 5. Presented by Sir W. C. Trevelyan, Bt.

53. Portion of the trank of a fossil tree from the dirt bed, Portland (p. 30). Presented by T. Foot, Esq.

54. Column of marble; Nether Haddon, Derbyshire (p. 22).

55. Silicified fossil wood, from the desert, near Cairo (p. 142). Presented by the late Dr. Buist.

56. Column of marble Sheldon, Derbyshire (p. 22).

57. Specimens of black Derbyshire marble, arranged in a columnar series, to illustrate the method of turning and polishing (p. 22). Presented, from the Great Exhibition, 1851, by Messrs. Hall, Derby.

58. Copy of the bust of the statue of Antinous as Bacchus; sculptured in Anston dolomite by Mr. C. H. Smith (p. 31). The stone presented by Mr. Grissell.

59. Series of speoihiens of Derbyshire alabaster, arranged similarly to No. 57 (p. 26). Presented by Messrs. Hall, Derby.

60. Polished marble slabs (p. 22).

61. Slab of alabaster from near Carrickmacross, Co. Monaghan, Ireland (p. 26). Presented by E. J. Shirley, Esq.

62. Polished section of a nodule of argillaceous ironstone, from the Bowling Company's works, Bradford, Yorkshire (p. 103). Presented by the company, from the Great Exhibition, 1851.

63. Column of coralline marble; Tideswell, Derbyshire (p. 22). Supporting No. 64.

64. Small column of volcanic ash from the Quantock Hills, Somersetshire. Presented by the Rt. Hon. Lord Taunton.

65. Polished circular slab of a septarium from the Oxford clay, Weymouth (p. 36).

66. Polished slab of serpentine; Lizard district, Cornwall (p. 21).

67. Column of marble; Kerry, Limerick (p. 25). Supporting No. 68.

68. Bust of William Smith, LL.D., by M. Noble (p. 40).

69. Octagonal slab with inlaid geometric design in varieties of marble (p. 24).

70. Polished table-top of serpentine veined with steatite; Lizard, Cornwall (p. 21).

71. Polished slab of stalagmitic aragonite, from Beni-souef, Egypt (p. 140). Presented by the late Prince Consort.

72. Polished Election of septarium from the Oxford clay, Weymouth (p. 36). Inlaid with sections of Ammonites and Belemnites (p. 153).

73. Column of marble; Ipplepen, Devonshire (p. 24). Supporting No. 74.

74- Bust of James Hutton, M.D., by Patric Park (p. 40).

75. Polished slab of rosewood marble; Derbyshire, (p. 22).

76 Inlaid pavement of Keene's cement, copied from a Roman mosaic pavement, discovered in 1795, in a villa at Seampton, near Lincoln (p. 35).

77. Polished slab of encrinital marble; Derbyshire (p. 23).

78. Column of encrinital marble; Flagg, Derbyshire (p:23). Supporting No. 79.

79. Tazza of red Derbyshire marble (p. 22).

80. Polished circular slab of stalagmitic aragonite, from Beni-souef, Egypt (p. 140). Presented by the late. Prince Consort.

81. Copy of the statue of the Farneso Hercules, sculptured in Portland stone by Mr. C. H. Smith (p. 29).. The stone presented by Messrs. Stewards & Co.

82. Specimen of Aritmowitea gigaideus, from the Portland beds (p. 30). Presented by G. Smith, Esq.

83. Polished table-slab of serpentinous marble; Ballinahinch, Galway (p, 22). Behind statue, of Hercules.

84. Column of marble; Wirksworth, Derbyshire (p. 22). Supporting No. 85.

83. Model of an ancient cross in black slate (p. 26).

86. Column of alabaster; Chellaston, Derbyshire (p. 26). .

87. Column of serpentine; Lizard, Cornwall (p. 21).

88. Column of grey granite; Aberdeen (p..17). Supporting No. 89.

89, Copy of a bust of Bubastis in greenstone, from Llanwnda, Fishguard, Pembrokeshire; by Mr. C. H. Smith (p. 21).

90. Portion of a tesselated pavement, by Messrs, Wyatt, Parker, &Co. (p. 37).

91. Column of marble; Ashford, Derbyshire (p. 22).

92. Column of marble; Allport, Derbyshire (p. 22).

93. Pilaster of encrinital marble; Rioklow Dale, Derbyshire (p. 23).

94. Column of Clonony marble; King's Co., Ireland (p. 25).

95. Table with inlaid top of Derbyshire and Staffordshire marbles (p. 24). Worked by the late Mr. Milnes and Mr. Redfern.

96. Large mass of crystallized quartz (p. 141), coating .galena (p. 100), and fluor spar (p. 139). From Weardale,. Durham. Presented by W. B. Beaumont, Esq., M.P.

97. Coloured sketch on ground of Benson and Logan's metallic cement (p. 36). On wall above.

98. Column of marble; Allport, Derbyshire (p. 22).

99. Pilaster of Ipplepen marble; Devon (p.24).

100. Table with inlaid top of Devonshire marbles (p. 24).

101. Column of marble; Allport, Derbyshire (p. 22).

102. Polished slab of grey granite; Aberdeen (p. 17).

103. Portion of a vein of auriferous or gold-bearing quartz, from the Grass Valley, Nevada country, California (p. 39), Presented by F. Catherwood, Esq.

104. Stereo-chromic painting, by Echter, of Munich (p. 36). On wall above.

105. Polished slab of red Peterhead granite (p. 17).

106. Column of marble; Wirkswortb, Derbyshire (p. 22).

107. Pilaster of serpentinous marble; Ballinabinch, Galway (p. 22).

108. Column of marble; Miller's Dale, Derbyshire (p. 22).

109. Polished slab of pink granite; Aberdeenshire (p. 17).

110. Pedestal of red Peterhead granite (p. 17). Supporting No. 111.

111. Cast in plaster of Paris of the Apollo Belvedere (p. 34).

112. Column of alabaster; Chellaston, Derbyshire (p. 26).

113. Specimens of Penmaen-mawr stone; Caernarvonshire (p. 21). Beneath Case VII.

114. Mass of copper glance (p. 75), with iron pyrites (p. 101), and quartz (p. 141); from Tomnadashan copper mine, Loch Tay, Perthshire. Presented by the late Marquis of Breadalbane. Beneath Case VII.

115. Pilaster of red Peterhead granite; Aberdeenshire (p. 17).

116. Section of a septarium (p. 36). Placed, with several miscellaneous objects, under the map.

117. Polished slab of Devonshire marble (p. 24).

118. Polished slab of Derbyshire marble (p. 22).

119. Polished slab of dolomitic conglomerate; Coity, Glamorganshire (p. 25).

(Nos. 117, 118, and 119 are beneath Case V.)

120. Block of Jasper; from Trutham, Cornwall (p.141). Presented by Montague Parker, Esq.

121. Polished slab of Devonshire marble (p. 24).

122. Polished slab of Plymouth marble (p. 24),

123. Frame containing eight slabs of Irish marble (p. 25). Presented by Messrs. Manderson, of Dublin.

(Nos. 121, 122, and 123 are beneath Case IV.)

N.B.-The southern end beneath the window is occupied by a collection of slates, described at p. 26.

124. Polished slab of porphyritic granite; Cornwall (p. 18). 125 and 126. Polished slabs of elvan; Withiel, Cornwall (p. 20).

127. Polished slab of schorl rock; Roche, Cornwall.

128. Inlaid slab of pieces of agate (p. 141), jasper (p. 141), porphyry (p. 20), &c., found as pebbles on the beach at Aberystwith, Cardiganshire. On wall above.

129. Column of marble; Stony Middleton, Derbyshire (p. 22).

130. Column of Plymouth marble (p. 24).

131. Polished slab of marble; Kitley Park, Yealmpton, Devon (p_:²⁴)-

132. Column of Plymouth marble (p. 24).

133. Polished slab of Devonshire marble (p. 24).

134. Slab of Shelly marble, from the Middle Peak, Derbyshire (p. 22).

135. Polished slab of Devonshire marble (p. 24).

136. Column of black marble; Moelfra, Anglesey (p. 25).

137. Column of marble; Wetton, Staffordshire (p. 24). Supporting No. 138.

138. Statuette of Bailey's Flora, in Coade's terra cotta (p. 58).

139. Pedestal of grey granite; Carnsue, Cornwall; with base of porphyritic granite, from Lamorna Cove, Land's End (p. 18). Supporting No. 140.

140. Tazza of red serpentine, the shaft entwined by a dolphin of (green steatitic serpentine; both from the Lizard, Cornwall p. 21). Worked by Mr. Pearce, of Truro.

141. Column of grey schorlaceous porphyry, from Laulivery, Cornwall (p. 20). Supporting Nos. 142 and 143.

142. Cube of serpentine; Portsoy, Banffshire (p. 22). Presented by the Earl of Seafield.

143. Tazza of red Aberdeen granite (p. 17).

144. Fluted column of alabaster, from Fauld, Staffordshire (p. 26); with foot of Derbyshire marble (p. 22). Supporting No. 145.

145. Large tazza of serpentinous marble; Ballinahinch, Galway (p. 22).

146. Column of schorlaceous porphyry (Lnxullianite), from Luxullian, Cornwall (p. 20). Supporting No. 147.

147. Vase of Derbyshire fluor spar (` Blue John,") said to be the largest and finest example known, having been executed for a royal personage at a cost of nearly 1001. (p. 139).

148. Pedestal of steatitic serpentine, with base of red and green serpentine, both from the Lizard, Cornwall (p. 21). Supporting Nos. 149 and 150.

149. Cube of granite; Portsoy, Banffshire (p. 17). Presented by the Earl of Seafield,

150. Tazza of Cornish serpentine (p. 21).

(We here cross to the northern end.)

151. Pedestal of grey granite; Trewoon, Cornwall (p. 18). Supporting No. 152.

152. Bast of the late Dr. Buckland, by H. Weekes, A.R.A. (p. 43)

153. Large pedestal and tazza of red Peterhead granite (p. 17). Worked, with many of the other Scotch granites, by Messrs. Me-Donald and Leslie, Aberdeen.

154. Pedestal of black marble; Castleton, Isle of Man (p. 25). with base of grey granite, from South Barrule, Isle of Man (p. 20). Supporting No. 155.

155. Bust of the late Professor E. Forbes, by J. C. Lough (p. 41).

156. Copy of the Dying Gladiator, in Parian cement (p. 35); the base coloured in imitation of marble. Executed by Mr. Belman, the patentee.

157. Pedestal of grey granite; Meldon, Devon (p. 18). Supporting No. 158.

158. Tazza of black Derbyshire marble (p. 22); inlaid with floral border in coloured marbles (p. 24).

159. Pedestal of grey granite, from Constantine, Cornwall (p. 18); with base of schorlaceous porphyry from Luxullian (p. 201. Supporting No. 160.

160. Tazza of Derbyshire rosewood marble (p. 22).

161. Large pedestal and tazza of alabaster; from Fauld, Staffordshire (p. 26). Worked by Messrs. Hall, of Derby.

162. Pedestal of grey porphyritic granite; Lamorna Cove, Cornwall (p. 18); with base of schorlaceous porphyry, from Luxullian (p. 20). Supporting No. 163.

163. Tazza of black Derbyshire marble (p. 22).

164. Mass of red oxide of copper, coated with malachite; from the mines of the Great Northern Copper Mining Company of South Australia, 200 miles north of Burrs Burrs (p. 95). Presented by the Hon. J. Baker.

165. Large mass of native copper; from the mine at the Ghostcroft, Mullion, Cornwall (p. 38). Presented by the Adventurers of the Trenauce mines.

166. Portion of a rich lead vein; from the Grassington mines, near Skipton, Yorkshire (p. 39). Presented by the Duke of Devonshire.

167. Pedestal of granite; Lee Moor, near Plympton, Devon (p. 18). Supporting No. 168.

168. Tazza of coralline marble; Matlock Derbyshire (p. 22).

169. Column of red Peterhead granite (p. 171). Supporting No. 170.

170. Bust of H.R.H. the late Prince Consort (p. 39).

171. Column of serpentinous marble; Ballinahinch, Galway (p. 22). Supporting No. 172.

172. Tazza of encrinital marble, Derbyshire; with base of black marble (p. 23).

173. Column of red marble; Cork, Ireland (p. 25).

174. Column of Clonony marble; King's County, Ireland. (p. 25). Supporting No. 175.

175. Tazza of Derbyshire marble (p. 22).

176. Column of marble; Michelstown, Cork (p. 25). Supporting No, 177.

177. Tazza of coralline marble; Devonshire (p. 24).

178. Column of granite; Hay Tor, Devon (p. 18). Supporting No. 179.

179. Tazza of Cornish serpentine (p. 21).

180. Column of porphyritic granite; Blackenstone, Devon (p.18). Supporting No. 181.

181. Tazza of dolomitic conglomerate; Coity, Glamorganshire (p. 25); with base of black marble.

182. Column of black Galway marble (p. 25). Supporting Nos. 183 and 184.

183. Cube of serpentine; Portsoy, Banffshire (p. 22). Presented by the Earl of Seafield.

184. Obelisk of Portsoy Serpentine (p. 22).

185. Pedestal of serpentinous marble Ehoscolyn, Anglesey (p.22). Supporting No. 186. Presented by the Hon. Owen Stanley.

186. Model in black Derbyshire marble (p. 22) of the Luxor obelisk now erected in Paris.

187. Column of marble; Babbacombe, Devon (p. 24). Supporting No. 188.

188. Tazza of marble; Wetton, Staffordshire; with black marble base (p. 24).

189. Column of encrinital marble; Matlock Bath, Derbyshire (p. 23). Supporting No. 190.

190. Tazza of red encrinital marble; Derbyshire; with black marble base (p. 23).

191 and 192. Polished slabs of stalagmitic carbonate of lime; Suisan Bay, California (p. 140). Presented by E. Seyd, Esq. 193 and 194. Two slabs of Verd antique (p. 22).

195. Column of grey granite; Craignair, Kirkcudbrightshire (p. 17). Supporting No. 196.

196. Tazza of black Derbyshire marble (p. 22).

197. Column of porphyritic granite; Shap, N. Westmoreland (p. 19). Supporting No. 198.

198. Tazza of Derbyshire rosewood marble, with black marble base (p. 22).

199. Column of marble; Wetton, Staffordshire (p. 24). Supporting No. 3 )0.

200. Tazza of shelly Derbyshire marble, with black marble base (p. 22).

201. Column of serpoutinous marble; Ballinahinch, Galway (p. 22). Supporting No. 202.

202. Tazza of Derbyshire stalagmitic marble, with black marble base (p. 22).

203. Column of rod Peterhead granite (p. 17). Supporting No. 204.

204. Bust of Her most gracious Majesty the Queen (p. 39).

205. Column of rosowood marble; Ashford, Derbyshire (p. 22). Supporting No. 206.

206. Tazza of black Derbyshire marble (p. 22).

207. Column of marble; One Ash, Derbyshire (p. 22). Supporting No. 208.

208. Ewer and plate of black Derbyshire marble (p. 22).

209. Pedestal of grey granite; Halvasso, Cornwall (p. 18). Supporting No. 210.

210. Bust of the late G. B. Greenough, F.R.S. By N. Bernard (p. 43).

211. Pedestal of serpentinous marble; Ballinahinch, Galway (p. 22). Supporting No. 212.

212. Bust of the late Sir H. T. De la Beche, C.B. By E. C. Papwortb, Sen. (p. 42).

213. Column of marble; Tideswell, Derbyshire (p. 22). Supporting No. 214.

214. Vase. of Derbyshire fluor spar (p. 139); on black marble pedestal.

215. Column of marble; Bonsall, Derbyshire (p. 22). Supporting No. 216.

216. Vase of Cornish serpentine (p. 21).

217. Pedestal of Cornish serpentine (p. 21). Supporting No. 225.

218. Bust of Sir James Hall. By Patric Park ( p. 41).

219. Pedestal of grey porphyritic granite; Cheesewring, Cornwall (p. 18). Supporting No. 220.

220. Bust of Professor J. Playfair. By M. Noble (p. 40).

221. Column of red granite; Ross of Mull, Argyleshire (p. 18).

At foot of western staircase.

In addition to the objects catalogued above there will be found in this portion of the building several groups of smaller specimens which are arranged, for convenience, in a series of table-cases distributed round the Hall. Of these cases Nos. I., II., and III., iv the eastern embayment, are filled with polished cubes of British ornamental stones, descriptions of which will be found under the following general headings, viz.: Marble (p. 22); Granite (p. 17); Elvin (p. 20); and Serpentine (p. 21). On the opposite side of the Hall, in the western embayment, are cases, Nos. IV.. V., VI., and VII., containing samples of our British building stones, the specimens being chiefly those collected by the Commissioners appointed in 1838 to select the most durable material for the construction of the Houses of Parliament. The physical and chemical properties of the stones were determined thy the late "Professor Daniell and Professor Wheatstone, the other members of the commission being Sir Charles Barry, Sir Henry De la Becht), Mr. William Smith, and Mr. Charles. H. Smith. The specimens submitted to the Commissioners and on which they reported (Report of Building Stone Commission, 15th July 1839), were, by the order of the Lords of the Treasury, placed in this Museum, and the collection has since been augmented, partly by private donations and partly by contributions from the Geological Survey. For a description of the Sandstones, see p. 28; of the Limestones, p. 28; of the Dolomites, p. 31; and of the Granites and Elvans, 17 to 21.

Case VIII., on the western side, near the statue of the Apollo Belvedere, is devoted to examples of hard stones used for the purposes of grinding and polishing (p. 32). On the eastern side, near the large alabaster tazza, stands Case IX., containing an interesting collection, intended to illustrate the preparation and uses of gypsum or plaster of Paris (p. 34), whilst the adjacent case, No. X., is occupied by samples of crucibles and melting pots, noticed at p. 37.

The wall-space on the eastern side of the Hall is decorated with British ornamental stones, commencing with a screen extending from the southern end to pilaster No. 33. In this screen, which is from the design of Mr. Charles F. Reeks, architect, the central panels are of the Ballinahinch serpentinous marble, surrounded by grey Derbyshire marble, in which run borders of guilloche and fretwork; the former of red Staffordshire marble and Derbyshire anhydrite, the latter of similar red marble and Derbyshire stalagmite. The pilasters and architrave are of Lizard serpentine, whilst the base is of russet and bird's-eye marble from Derbyshire.

The screen between pilasters Nos 33 and 40 exhibits a large central panel of marble from the Mumbles, Swansea, the smaller panels being of Ipplepen marble, Devon; while the cornice is of Lizard serpentine, and the remainder of Derbyshire marbles.

In the space between pilasters Nos. 40 and 44 the circular centre is of Derbyshire rosewood marble, and the remaining panels of encrinital, coralline, and other varieties of Derbyshire marble, whilst the ground in which the whole is inlaid is of Fauld alabaster, and the base of reddish syenitic granite from Mount Sorrel, Leicestershire.

Scotch granites and marbles occupy the wall-space between pilasters Nos. 44 and 48. On the base of grey granite from Ken-may (Aberdeenshire) rests a moulding of red Corrennie granite, above which is a dado of grey granite from Cairngall, near Peterhead, surmounted by a cornice of pink granite from the Isle of Mull. In the upper part the ground is of red granite from the Stirling hill quarries, near Peterhead, whilst the central circular panel is of Strathdon marble (Aberdeenshire), and on each side of this is a panel of hornblendic porphyry from Mayon, near Huntly, Aberdeenshire. The remaining panels, which, in most cases correspond on each side are, commencing from below, of Kingswell porphyry (Aberdeenshire); Glen Tilt marble (Perthshire); Sutherlandshire marble on the left hand, and Portsoy serpentine on the right; Tiree marble, Hebrides; and Rubislaw granite, Aberdeenshire.

The tesselated pavement in the centre of the Hall (p. 37) is surrounded by slabs of grey Aberdeen granite, and these again by slabs of red Peterhead granite, the whole being bordered by a guilloche in Minton's encaustic tiles formed of compressed coloured clays. Similar tiles form a pavement at the top of the steps leading from the vestibule, and again on the north of the tesselated pavement around the large granite tazza. The remainder of the pavement is of Portland stone (p. 29), as also are the columns supporting the roof.

While examining the contents of the hall it should be borne in mind that the object of this section of the museum is almost purely technological, its main purpose being the illustration of the applicability of the rocks of the United Kingdom to purposes of architecture and ornament. Hence the geological student who wishes to study the physical characters of our rocks rather than their industrial uses must be referred to the series of British rock specimens in the upper gallery and to the mineral collection on the principal floor, detailed catalogues of both of which have been published.

Granite

In its typical varieties granite consists of a crystallo-granular mixture of the three minerals, felspar (p. 144), quartz (p. 141), and mica (p. 145). The felspar, which usually forms the chief constituent, is in most cases the common potash-felspar called orthoclase; but this is frequently associated with a soda-bearing species which is commonly oligoclase, but in some cases appears to be albite (p. 144). The orthoclastic felspar often occurs in large well-formed crystals embedded in a fine-grained base, thus producing the beautiful porphyritic granites, of which some fine examples are exhibited (p. 20).

Certain varieties of granite rapidly suffer disintegration, while others are remarkable for their extreme durability. Combined with a considerable degree of hardness, this durability renders granite highly valuable as a building stone for bridges and other massive structures, while the toughness of the hornblcndic varieties makes them especially suitable for road materials. At the same time the beauty of many granites and the high polish which their hardness renders them capable of receiving, recommend their use for purposes of ornament. The industrial applications of granite are, however, greatly restricted by its expense.

Granites of Scotland

Steps at Entrance. Pilasters on each side of Stairs from Hall, and Nos. 33 and 115.—Screen 4.—Slabs surrounding tessolated pavement.—Pedestals, Columns, Nos. 36, 88, 102, 105, 109, 110, 143, 149, 153, 169, 195, 203, and 221. Cubes in Table Cases III. and VII.

The granite of Aberdeen, especially that from the quarries of Dancing-Cairn, Rubislaw, and Tyrebagger, is much used in the metropolis for kerb and paving stones; the usual colour is grey, but some red granite is also quarried. Around Peterhead the red granite prevails, hence it is usually distinguished as the Peterhead granite. The principal quarries are those of Black Hill, four miles west of Peterhead, belonging to the Governors of the Merchant Maiden Hospital of Edinburgh, those on the estates of the Earl of Errol, at Boddam, at Longhaven, at Cairngall, and at Revs. The Sheerness Docks were built mostly with stone from these quarries. The Stirling Hill quarries, at Boddam, furnished she pillar of the Duke of York's monument, the Seafield quarries. The abacus. The beautiful pillars in the library of the British Museum were obtained from Longhaven; the cost for transport at the time they were worked being something almost fabulous, so great were the difficulties attending their removal. The pillars in Fishmongers' Hall are from the Stirling quarries, as are also the bases of the monuments of Pitt and Fox; while the polished pillars of the Carlton Club House are from the quarries near Peterhead.

The fine pink and red granites of the Isle of Mull are now largely worked by the Scottish Granite Company, and have been recently employed in the erection of the Albert Memorial in Hyde Park. Specimens of Scotch granites arc exhibited from the following localities :—Peterhead, Aberdeen, and Corrennie Hill, Aberdeenshire; Portsoy, Banffshire; Delmore, Sutherland; Oben and Mull, Argyllshire; Tiree, Hebrides; and Craignair, Kirkcudbrightshire.

Granites of Ireland

Base of Sides in Vestibule. Column No. 1. Slabs Nos. 29 and 30. Cubes in Table Case III.

The most extensive granite district in Ireland, and indeed in the whole of the British Islands, stretches south from Dublin, through the counties of Wicklow and Carlow into Kilkenny and Wexford, occupying an area 70 miles in length, and from 7 to 17 miles in width. Granite occurs also in the south-east of Down, and is extensively quarried at Newry, whence it is sent by water to the north of Ireland; whilst in the same county granite forms the range of the Mourne mountains. In the western portion of Donegal there is a large extent of this rock, which here partakes of a gneissose character; and again, in the west of Galway, granite covers a considerable area.

The granite of the Wicklow range is the most extensively used. It varies in its quality, that near Kingstown being coarse and hard, while that from Ballyknockin or Golden Hill is much finer, and therefore fitted for ornamental work. The granite of Down is of a darker colour, and finely crystallized.

The Galway granite is of a reddish colour, containing large crystals of flesh-red felspar. That of Mayo is of a dark bluish grey colour, while that of Tyrone is reddish.

The following localities are represented in the collection Kingstown, Killiney, Dalkey, Kilgobbin, and Glancullen, co. Dublin; Glenaree and Ballyknockin, co. Wicklow; Ballyholland, near Newry, co. Down; and Galway.

Granites of Cornwall and Devonshire

Pedestals and Columns Nos. 8, 139, 141, 151, 157, 159, 162, 167, 178, 780, 209, and 219. Cubes in Cases III. and VI.

By reference to the Geological Map which is suspended on the western wall the granite districts of western England—coloured pink—will be seen, appearing as five islands of granite rising out of the surrounding killas or clay slate; and around these are a few smaller outlying masses.

The more important quarries from which this durable stone is obtained are those of Lamorna, to the west of Penzance; the Penryn quarries; the quarries near St Austell; Hensborongh, near Lostwithiel; the Cheesewring, near Liskeard; Gunnis Lake, near Calstock; the Delank quarries near Padstow; and the Dartmoor quarries in Devonshire. In 1865, 500,000 feet, about 40,000 tons, of the value of 75,000l. were shipped from Cornwall, and about 5,000 tons from-Devonshire.

The following is from the pen of Sir Henry De la Beche (Report on the Geology of Devon, Cornwall, and West Somerset).

"There is much good granite on Dartmoor, though it is not always sufficiently accessible to be carried long distances; the chief places where it is worked in large quantities and afterwards exported are, Hey or High Tor on the east, and near King Tor on the west. The granite from the former place is conveyed by a tramroad to the Stover canal, down which it is carried in boats, and afterwards dOwn the feign to Teignmouth, to be shipped for its destination. That from the west side of the moor is conveyed by the Prince's Town and Plymouth trammed to the latter place and shipped.

The continuation of the Hingston Down granite is worked up the Tamar near New Bridge and exported from Morwellham. A very hard variety is obtained upon the higher part of the Down, and has been employed advantageously for pavements. * * * The chief quarries in the eastern or hard part of the Hensborough mass of granite are those of (the late) Mr. Austin Treffry, up the Par Valley, commonly known as Lostwithiel granite. Extensive quarries aro there worked, and the stone is brought to the head of the canal near Ponsmill, upon which it is conveyed to Par harbour; and there shipped. * * * The Carn Menelez mass has furnished the granite most commonly known as Cornish. It is nearly altogether shipped at Penryn, where it is brought variable distances from different quarries in the vicinity, many situated in the, parish of Mabe."

Since the above report was written the quarries on the eastern edge of Dartmoor have ceased working; those at the Cheesewring near Liskeard have been opened, and stone of a beautiful quality is raised and exported in large quantities from Looe. The Lamorna quarries to the west of Penzance and a large quarry, Mill Hill, in Madron, have also been worked. The stone obtained from those quarries is of excellent quality, and it can be obtained of very large size.

The following great works, amongst many others, have been constructed entirely or in part of Cornish granites. The Penryn and Lamorna granites have supplied Portland breakwater; Keybant Docks for the Steam Navy; Commercial Docks, London; the Hull, Great Western, and Birkenhead Docks, and the National Works at Chatham and Portsmouth, together with the Scutari monument. The plinth for the railings of the British Museum is from the Carnsew quarries, and the towers, including the lodge for gates, &c., from Constantine. The Constantine granite has been used for tho Wellington Memorial at Strathfieldsaye, the shaft of the column being 30 feet in height in one stone. The Lamorna quarries produce about 60,000 feet per annum.

The Cheesewring granite has been used in the London Docks, Westminster Bridge, the Thames embankment, Rochester Bridge, the docks at Copenhagen, the Great Basses Lighthouse near the island of Ceylon, and for the tomb of the Duke of Wellington in the crypt of St. Paul's Cathedral. These quarries produce from 8,000 to 10,000 tons of stone per annum, and about a similar quantity is annually shipped from the quarries near Par.

Cornish granites are exhibited from the following localities :—.-Lamorna Cove, Paul, Castle-an-Dines, Marazion, Madron, Ludgvan, Constantine, Carnsew, Mahe, Penryn, St. Austell, St. Blazey, Lanlivery, Luxullian, Roach, Lanivet, Withiel, Bodmin, Castle Quarry, St. Breward, Cardynham, St. Neots, Trewoon, Halvasso, and the Cheesewring.

Devonshire granites are exhibited from the Fremator quarries near Tavistock, and from Blackenstone and Heytor, Dartmoor.

In addition to the granites from our western counties noticed above, a few other specimens are exhibited from localities of much less importance. Shapfell, in Westmoreland, furnishes a beautiful porphyritic granite represented by the Column No. 197; while Mount Sorrel, near Charnwood Forest in Leicestershire, yields a pink syenitic granite, which has been employed in the decoration of the eastern wall. The base of the pedestal No. 154 is from the boss of granite which penetrates the surrounding schists on the southeastern side of South Barrule, one of the highest points in the Isle of Man. The granite of Lundy Island is represented by several cubes in Cases III. and VII. As these specimens were all obtained from near the exposed surface they sufficiently attest the durability of the stone, but probably much better varieties will be found as the workings increase in depth.

From the Channel Islands large quantities of granite are exported, chiefly for use as London road-metal. Specimens are exhibited in the table-cases from the quarries of Mount Mado and La Perruque in Jersey, and from Guernsey and its dependency, the little island of Herm.

Porphyries. Elvans. Syenites. Greenstone

Columns and Slabs Nos. 1, 89, 113, 124, 125, 126, 141, 146, 162, 180, and 219. Base of Pedestals 159, 162. Cases III., VII.

Under the generic porphyry are grouped all varieties of rocks, consisting of a matrix in which distinct crystals are embedded; the term thus referring rather to the physical structure of the rock than to any more essential character, and hence embracing many varieties which in chemical composition are widely distinct. True porphyry consists of crystals of felspar in a felspathic base : the type of this rock being the ancient red porphyry of Egypt. Many of the Cornish and Devon granites in the collection are eminently porphyritic, and we may especially notice the pedestal and columns Nos. l and 180 on the eastern side and Nos. 141 and 146 on the western side; the latter two, from Lanlivery and Luxullian in Cornwall, have been employed, especially by the late Mr. Austin Treffry, for ornamental purposes. The sarcophagus for the late Duke of Wellington, now in St. Paul's, is formed of one huge mass, of the same character as the red and black variety in the column, No. 146, and in the bases of the pedestals Nos. 159 and 162. This beautiful rock, which, from its locality, has recently been called Luxullianite, consists of large crystals of pink orthoclase-felspar, associated with much schorl, or black tourmaline, and a small quantity of quartz.

Upon reference to the Geological Map a number of bands coloured orange-red will be seen traversing both the granite and slate rocks of Cornwall, having a main general direction from the north of east to the south of west. These represent dykes of what is locally termed elvan, a rock closely allied to granite, from which indeed it principally differs in the general absence of mica. Frequently the elvans become porphyritic, being chiefly composed of a felspathic or a quartzo-felspathic base, containing crystals of felspar and quartz, sometimes schorl, and occasionally, though rarely, mica.

Sir Henry De la Beche remarks of the Cornish elvans, "For durable stone the harder elvans of this district, particularly when of good cream and other light colours, may be considered as the best building materials in it; their durability and appearance may be seethin many churches and old mansions, where the finer carvings of the ornamental parts are as sharp as the day they were put up. Occasionally the felspar crystals may have been decomposed and have been washed out, but the siliceo-felspathic base has remained firm, thus preserving the sharp character of the work." Much useful information upon the building and ornamental stones of Devonshire and Cornwall will be found in The Report on the Geology of Cornwall, Devon, and West Somerset, by Sir Henry T. De la Beche.

In the Table Cases III. and VII. will be found specimens of elvans from Mayen, Land's End; Marazion, near Penzance; Breague, near Helston; Porkellis, Wendron; Roscrow and Trevailes, Penryn; Newhaven, Truro; near Newquay; Pentuan and Dowgas Mine, St. Austell; Withiel, Lanivet, St. Neots, and Tremore, near Bodmin; St. Dennis; Camelford; and Meldon, Okehampton, Devon.

Granites frequently contain various accessory minerals, of which one of the most common is the lustrous mineral hornblende. This sometimes occurs to the entire exclusion of the mica, and the rock thus formed, consisting essentially of an aggregate of felspar, quartz, and hornblende, is commonly termed Syenite, a name derived from the ancient quarries of Syene in Upper Egypt, whence a homblendic granite was formerly obtained. Several examples of syenitic granites will be found in the collection amongst the Guernsey and Irish specimens.

On the disappearance of the quartz in a syenite, a rock is obtained consisting solely of felspar and hornblende. Such a rock generally passes under the name of Greenstone or Diorite, of which an example from Llanwnda, in Pembrokeshire, will be seen in the copy of a bus of Bubastis (No. 89) near the western entrance to the theatre. The Penmaen-mawr stone (No. 113, beneath Case VII.) is a felspathic grecustone, which, from its toughness, forms a valuable paving material. It occurs as an intrusive mass in the Lower Silurian rocks near Conway, in Caernarvonshire.

Serpentines

Cornish Serpentines

Slabs, Columns, &c., Nos. 7, 66, 70, 87, 148, and 217. Tazze, 140, 150, 179. Vase, 216. Screen on Eastern Wall. Cubes in Case III.

The Serpentine,—so called from the supposed resemblance of the rock to the skin of a serpent,—which is found in quantity at the Lizard, is undoubtedly the most beautiful of the ornamental stones of this country. The variegated colours on which its elegance depends, are usually dark rich shades of red and green, irregularly mingled, and often relieved by white veins of steatite or soapstone. Near to and to the eastward of Cadgwith a very beautiful variety of reddish serpentine occurs, studded with brilliant laminas of diallage, a silicate of lime, magnesia, iron, &c., allied to augite. Both the serpentine and the associated steatite are essentially hydrous silicates of magnesia. Formerly the steatite, from the "Soap Stone Rock," near Mullion, was sent in considerable quantities to Bristol, where it was used in the manufacture of carbonate of magnesia; and at one period was employed at Swansea in the manufacture of earthenware, but it is no longer worked.

For purposes of ornament this elegant stone is well adapted, being moderately soft, but not brittle, and therefore easily worked, while it is sufficiently hard to receive an excellent polish. It was long thought that blocks of serpentine of a large size could not be obtained; quarries have, however, been opened, and it is found that the size and solidity of the blocks increase with the depth from the surface. There are few spots around the British coast more beautiful and grand than Keynance Cove near the Lizard, where the serpentine rock in all its varied dyes, is polished by the beat of the Atlantic waves, and, in contrast with the white sands of the shore, is rendered still more striking and characteristic.

Irish Serpentines

Pilasters Nos. 40 and 107. Screen on E. Wall. Slabs, Columns, 4.c., 35, 83, 171, 201, and 211. Tana, 145.

Serpentine frequently occurs in intimate association with limestone, forming a mixed rook often of great beauty. The celebrated verd-antique (verde antico of the Italians) is a rock of this kind (see Nos. 193, 194), Somewhat similar serpentinous marbles occur in Ireland, especially in the west of Mayo and Galway, which afford beautifully variegated green and white specimens. The green Connemara marble, known to architects as "Irish Green," is obtained at Ballinahinch in Galway, the most valuable quarries being situated near Clifden, whence this fine material is largely exported..

Anglesey Serpentine

Pedestal No. 185.

Among the metamorphosed Cambrian rocks of Anglesey serpentine occurs frequently associated with limestone (see Descriptive Catalogue of the Rock Specimens, 3rd ed., p. 15). An example of this green serpentinous marble is furnished by the pedestal before us, from Rhoscolyu, near Holyhead..

Scotch Serpentines

Obelisk No. 184. Cubes Nos. 142 and 183.

Serpentine rocks occur in various localities in Scotland, especially in Banffshire and Aberdeenshire, and again in the Shetland Isles, where they form the matrix of the chrome iron oro. As will be seen from the specimens, very fine varieties for ornamental purposes are obtained from Portsoy, on the north coast of Banffshire, whence this elegant material was formerly exported.

Marble

It is a common error to comprehend under the name of a marble every stone which is capable of receiving a polish and of being applied to purposes of decoration, such as serpentines, porphyries, alabasters, and other ornamental stones. In strictness, however, the term should be limited to those varieties of carbonate of lime which are sufficiently hard and compact to be susceptible of polish.

Although by no means restricted to any particular strata, yet the marbles of this country are usually obtained from the palmozoic rocks, being especially abundant in the Carboniferous and Devonian systems. The Carboniferous or Mountain Limestone-which rises in our northern counties in a broad ridge or anticlinal curve forming the Pennine chain-furnishes valuable marbles in certain districts, especially in Derbyshire and on the borders of Staffordshire; whilst the fossiliferous limestones of the Devonian system-still older than those of the Carboniferous series-yield the valuable marbles of South Devon..

Derbyshire Marbles

Pilaster 93. Columns, Nos. 2, 21, 24, 32, 34, 38, 39, 43, 54, 56, 63, 75, 77, 78, 91, 92, 98, 101, 106, 108, 118, 129, 134, 160, 163, 168, 172, 186, 189, 198, 205, 207, 208, 213, and 215. Tazze, Nos. 79, 158, 175, 190, 196, 200, 202, and 206. Screen 3. Inlaid work, Nos. 10, 14, 69, 95, and 158. Cubes in Case I.

The rocks of Derbyshire are rich in ornamental marbles, which, from their beauty, and in many respects their curious characters, have been largely employed for decorative purposes. They are usually distinguished by their colour—as white, grey, dove, blue, black, and russet marbles; or by physical peculiarities, dependent mostly upon their fossil contents, as bird's-eye, dog-tooth or muscle, entrochal, shelly, and breccia marbles. The limestone rocks of Derbyshire are divided into four classes, known as the 1st, 2nd, 3rd, and 4th limestones, which are separated from each other by an amygdaloidal greenstone, called toadstone,—probably a corruption of the German Todtstein, or dead stone, in allusion to these interbedded trap rocks being barren of lead ore compared with the adjacent limestones. The ornamental marbles are, however, mostly confined to the first three formations. From the upper beds of the 1st and 3rd series is principally obtained the well-known entrochal or encrinital marble, so called from the presence of abundant fossil remains of encrinites, or "stone lilies." These were echinoderms belonging to the Crinoidea,—an order of which there are but few living representatives, compared with the abundance which existed in the Palaeozoic and Secondary periods of the world's history; the beautifully formed and numerously jointed Pentacrinus caput Medusæ, which is occasionally dredged from great depths on the coral reefs of the West India Islands, being the finest living example of this ancient family. The encrinite consisted of a long jointed column attached by one extremity to the sea-bottom, and supporting at the opposite extremity a cup-shaped body, from which radiated several articulated arms furnished with ciliated appendages. The entire structure was rendered flexible by the internal calcareous skeleton being composed of numerous cylindrical or bead-like joints. Mr. Parkinson states that the upper part of the skeleton of one species of encrinite consisted of nearly 27,000 ossicles or small bones. These being dislocated are cemented together, in the marble, by carbonate of lime; and being, in the process of manufacture, cut in many different sections, and polished, they assume a variety of forms.

The perforations in the centre of the joints afford facilities for stringing them as beads; in this way these fossils were used as rosaries, and they are still known in northern England as St. Cuthbert's beads.

The black marble is obtained from the second limestone, especially in descending into Monsal Dale from Little Longsdon. The shell-marble is also yielded by these rocks; this variety contains the remains of brachiopodous molluscs, so called from having two long ciliated arms (βραχίων an arm, ποὺς, a foot). These are "shell-fish," furnished with two valves which are never quite equal, but since each valve is equal-sided the forms are symmetrical. In these points they differ from the ordinary bivalves, which are mostly equivalved but never quite equilateral. From the resemblance of these brachiopodous shells to antique lamps, they are commonly called "lamp-shells;" the hole corresponding to that which in a lamp admits the wick, serves in the lamp-shell for the passage of the pedicle by which the animal attaches itself to submarine objects. The ,S'pirifer and Producta, two genera of the above class, are the most abundant in these limestones.

The three upper limestones, from which these marbles are obtained, extend, according to Farey (General View of the Agriculture and Minerals of Derbyshire), over an area of nearly 51,500 acres.

In this collection the following localities are represented, viz., Wirksworth, Middleton, Bonsall, Matlock, Nether Haddon, Allport, Monyash, Oneash, Sheldon, Ashford, Flagg, Stony Middleton, Buxton, Miller's Dale, Ricklow Dale, and Tideswell.

A cube of encrinital marble from the mountain limestone of Dent, in the west of Yorkshire, is placed with the Derbyshire marbles in Case I..

Staffordshire Marbles

Columns Nos. 137 and 199. Tazza, 188. Inlaid work, 10, 69, and 95. Cubes in Case II.

The marbles of Staffordshire present but little variations from those of the adjoining county. Their geological positions are the same, and they present the same general characters. Specimens are exhibited from Wetton and Ecton.

The variety of coloured limestones which the two counties of Derbyshire and Staffordshire produce has naturally led to a manufacture almost peculiar to them. Mosaic work of a very beautiful description is executed in these materials. Indeed, many of the inlaid tables, tazze, and other ornaments, produced from Derbyshire and Staffordshire materials, are worthy rivals of the far-famed Florentine works. In addition to the inlaid tables in this hall, there will be found some interesting specimens of this kind of work in the horse-shoe case on the principal floor..

Devonshire Marbles

Pilasters, 44 and 99. Screen 2. Columns, Slabs, &c., Nos. 4, 5, 73, 117, 121,`122,130, 131, 132, 133, 135, 177, and 187. Inlaid Table, 100. Cubes in Case I.

The limestone formations of Devonshire, from which ornamental marbles are obtained, may be said to be confined to the districts extending from Torbay to a few miles beyond Newton Bushell and Totness, and to the:neighbourhood of Plymouth; the limestones of the carboniferous series of North Devon being rarely worked for ornamental purposes.

Marble works are extensively carried on at St. Mary Church near Torquay, the Babbacombe limestones yielding some interesting varieties of the red, grey, and variegated marbles. Many blocks are almost entirely formed of fossil corals; these are known as madrepore marbles; and Mr. Austen, who has examined these formations with great eare, has clearly shown that the origin of both the Torquay and Plymouth marbles is of an analogous character to that of the coralline formations now taking place in the Pacific Ocean : that these limestone masses are indeed due to the slow, but ever-constant labours of one of the minute forms of animal life.

At Ipplepen there is an extremely handsome variety of a reddish marble, and some of a nearly similar character occurs near Totness. The limestones of Plymouth are not generally so handsome as those of Babbacombe, but many very fine examples may be obtained. The quarries of Oreston, near Plymouth, furnished the stone employed in the construction of the Plymouth breakwater, and in connexion with the use of this limestone for that purpose, one curious circumstance has attracted attention. Between high and low water-mark the boring molluscs (pholas dactylus, pholas from pholeo, to bore) so perforated the limestones that it was thought necessary to replace them by blocks of granite, which, being much harder than the shells, of these animals, resists their action. Some examples of these boring animals, and of the rocks perforated by them, will he found in the wall-case 43, in the upper gallery, eastern side.

Devonshire marbles are exhibited from Babbacombe, Bradley, Ipplepen, Buckfastleigh, Ogwell, Chudleigh, Kitley Park, and Plymouth..

Marbles of Bristol, Isle of Man, &c.

Cubes in Case II. Pedestal 154. Columns 11, 16, and 136.

The rocks which rise on either side of the Avon have been always celebrated for their picturesque character. This is not entirely dependent upon their bold outlines; their varied colours and their irregular forms adding greatly to the grandeur of the scene. Several varieties of ornamental marbles are exhibited from the rocks of this district, especially from the carboniferous limestone of Clifton. Like those already described, these marbles are fossiliferous; en-crinites are often common, fish-palates are detected in some, and many of the beds of coralline limestone are extremely interesting from the resemblance they bear to coral reefs.

Among the British marbles in Case II. will be found a specimen of the argillaceous limestone commonly called "Landscape marble," in allusion to the peculiar dcndritic markings which it exhibits. It occurs in the Penarth or Rhmtic beds (p. 156), in the neighbourhood of Bristol; and was formerly much used for the manufacture of small ornaments. Attention may also be directed to the specimens of conglomerate from Glamorganshire (Nos. 119 and 181), which occurs at the base of the New Red Sandstone, resting frequently on the upturned and denuded edges of the carboniferous limestone. The fragments forming the conglomerate or "pudding stone" are united by a cement sometimes calcareous, but usually magnesio-calcareous or dolomitic. With these dolomitic conglomerates may be noticed some specimens of the peculiar breccia-marble of the Isle of Man (No. 16).

In Case II. will also be found a few other marbles of less importance than those already noticed. These are from Somerset-shire, Herefordshire, and South Wales. The carboniferous limestone of the Isle of Anglesey has furnished the black marble employed for the columns Nos. 11 and 136..

Irish Marbles

Pilaster 48. Columns &c., 41, 67, 94, 123, 173, 174, 176, and 182. Cubes in Case II.

Ireland is rich in marbles; indeed in no other part of the British Islands is the carboniferous limestone developed on so grand a scale. Extending over a great central plain, 120 miles E. and W. from Dublin to Galway bay, and about the same distance north and south, it forms the characteristic rock throughout the greater part of the island, and attains in the southern counties the prodigious thickness of nearly 3,000 feet. The more valuable quarries are in the counties of Kilkenny, Carlow, Galway, and Mayo; from these several varieties of marble are raised, especially the black marble, next to which in importance are the dove, mottled grey, and white marbles. The Galway marbles are well known, but the beds in the quarries are usually thin, and there are but few of them which are fit for working—still fine blocks can be raised. It is quarried principally at Menlo, on the banks of Lough Corrib, the cost of obtaining it being greatly increased by the difficulty of getting rid of the water which flows into the quarries from the lake, the beds being near surface level. White marble is obtained in Connemara and in Donegal; the limestone of the former district is hard and fine, and is the strongest which has been found, while that of the latter is so exceedingly coarse that it cannot be used for fine work. The white Connemara marble cannot, however, be procured in large blocks free from streaks, which pass through the blocks parallel with the beds. Those counties also produce the bluish white and pink tinted marbles.

Black marble is principally obtained from Kilkenny, Galway, Chnrchtown, Donerail, Kerry, and Tipperary; white marble from Connemara, Donegal, Chnrchtown, and Kerry; and coloured marbles are scattered over all the districts in which the limestones occur.

The serpentineus marble of Connemara has been already noticed at p. 22.

Irish marbles are exhibited from Clonony, King's Co.; Phcenix Park and Finglass_'Dublin; Mitchelstown, Cork; Kenry and As-keaton, Limerick; Miuto, Galway; Ballinahinch; the Twelve Pin Mountains; and Rossvella and White Craig Quarries..

Scotch Marbles

Screen 4. Block No. 13. Cubes. in Cases II. and III.

An interesting variety of marble is exhibited from Tiree, in the Hebrides, where it occurs associated with the Laurentian gneiss.

The Tiree marble consists of a base of pink limestone, through which are disseminated granular masses of a dark green augite, giving the stone a porphyritic appearance. The bust of Sir H. T. De la Beebe in the library of this institution is supported on a fine block of this marble.

Alabaster

Sides of Vestibule. Columns Nos. 86, 112, and 144. Tazza 161. Slab 61.

The term alabaster was formerly applied to a stalagmitic variety of carbonate of lime much used by the ancients for ornamental purposes, especially fur the manufacture of small vases for holding precious ointments; whence such vessels received the name of "alabastra." This "Oriental alabaster," of which the Algerian "onyx-marble" is a well-known modern example, must be carefully distinguished from the totally distinct mineral which is at present called alabaster; that name being now applied to the fine massive or granular crystalline varieties of gypsum (p. 34). This mineral, which occurs abundantly in the New lied or Keuper Marls of our midland counties, is a hydrous sulphate of lime, containing, when pure, sulphuric acid 46.51, lime 32.56, water 20.93. Owing to the presence of oxide of iron and other impurities, the mineral is rarely uniform in tint, but is generally clouded and streaked with red, as seen in the specimens exhibited. These are from Fauld, in Staffordshire; and Chellaston Hill, near Ashbourne, in Derbyshire.

The principal demand for alabaster is by the potters in Staffordshire, who form their moulds of plaster of Paris from it. It is therefore called potter's stone, and sells at about 9s. per ton of 2,400 lbs. (the long ton). In working the potter's stone the fine blocks are selected, and sold to the turners of alabaster ornaments. No. 59 is an illustration of the process of working and polishing this material for ornamental purposes.

Slate

This valuable material is a highly indurated argillaceons rock, readily cleaved in certain directions into thin laminae or plates; and upon this peculiar fissile structure depends to a great extent its economic value.

The beds, deposited originally as a fine muddy sediment, appear to have been subjected, long after consolidation, to the action of intense lateral pressure; the effect of which was not only to contort the beds, but also to induce a re-arrangement of the particles of the rock, the flattened sides of these particles being forced by the lateral compression into positions transverse or at right angles to the direction of the pressure, and hence the rock readily cleaves parallel to that direction in which all the particles are thus definitely arranged. All contorted strata are not, however, cleavable.

Physical experiments on slaty cleavage have shown that a similar, though much less perfect fissility may be artificially developed by simple mechanical compression; the direction of the induced cleavage being always perpendicular to that of the applied pressure. The perfection of the natural cleavage is admirably shown by the Welsh specimens near the western window.

For further information on this subject, see Descriptive Guide to the Rock Specimens, 3rd edition, p. 13.

Slates are subject to considerable variation both in colour and texture: good roofing slate should absorb but little water, and be so compact as not to be decomposed by the action of the atmosphere.

Mr. McCulloch informs us (Commercial Dictionary) that the use of slates in covering houses is entirely European; from the Hellespont to China there is not a single slated house, although slate is as abundant in Asia as it is in Europe. The duty on slates carried coastways was repealed in 1831, and since that time it has been extensively employed for various purposes to which it was not formerly applicable. Slabs which are not fit for splitting into roofing slates arc now used as floorings, being cut with a circular saw into pieces of from half an inch to two inches thick..

Slates of North Wales

Column No. 12. Collection at the south, or Jermyn. Street end of Hall, west side.

The slate quarries of North Wales have long been celebrated for the excellent character of the slates which they produce. The most important quarries are the following, which are given with their shipping ports, and the geological formations to which they belong :—

Penrhyn — Cambrian. Bangor — Cambrian.

Llanberis — Cambrian. Dinorwic — Cambrian.

Ffestiniog — Cambrian. Port Madoc, Lower Silurian.

Llangollen — Cambrian. Llangollen, Upper Silurian.

Machynlleth — Cambrian. Aberdove , Lower Silurian.

Royal Slate — Cambrian. Bangor, Cambrian.

There are many smaller works near Conway and Caernarvon. The slate quarries of North Wales produce at least 350.000 tons of roofing slates and slabs per annum. The annual produce of this district may be valued at 700,000l.; and there are employed in the production of slates and slabs upwards of six thousand men and boys in North Wales alone..

Delabole Slate, of the Devonian rocks

East side of Case VI.

The Delabole slate quarries, situate near Tintagel, in Cornwall, have been long celebrated for producing a durable material combining considerable lightness with strength. In 1602 Carew, in his Surrey of Cornwall, speaks of healing stones (in many districts roofing slates are still called hailings or healings, probably from hele or hail to hide, and hence the name of helier given to a tiler or slater) :—"In substance thinne, in colour faire, waight light, in lasting long, and generally carrieth so good regards as (besides the supply for home provision) great store is yearly conveyed by shipping both to other parts of the realme, and also beyond the seas, into Britain and Netherland." Borlase, in 1758, speaks of the extent of the workings of Delabole. The Delabole quarries produce not only roofing slates, but flagstones or brick slates, which are highly esteemed for pavements in passages, courts, yards, &c. and for tombstones. The inscriptions upon old tombstones of the Delabole slate remain remarkably perfect, showing its durability when exposed to atmospheric influences. These slates are shipped at Tintagel and at Boscastle.

There are other slate quarries near Boscastle and near Launceston; and also in Devonshire, at Tavistock, near Plymouth, and at Kingsbridge. (See Mineral Statistics for 1858.)

Sandstones

Cubes in Table Cases IV., V., and VI.

A sandstone consists of small siliceous grains cemented together into a solid rock. The nature of the cementing material is important, inasmuch as it determines the durability of the stone; those varieties being most durable in which the cement is siliceous. The formation of sandstone generally is instructively illustrated by a specimen of recently-consolidated sand from Newquay, in Cornwall, and many similar examples exist around our western coasts, where hills of blown sand prevail. The water percolating through the upper layers dissolves the carbonate of lime, or of iron, and sometimes silica, which are re-deposited as cementing materials, on the evaporation of the water as it filters through the lower strata of the porous sand.

In texture and colour sandstones are subject to considerable variation, according to the size of the grains and the nature of the cement : the red colour exhibited by many sandstones is due to the presence of peroxide of iron.

Sandstones have always been favourite materials with the architect, and an extensive variety of specimens is therefore exhibited. Special description is however unnecessary, since every specimen is distinctly labelled, not only with the locality, but in most cases with the names of the buildings in which it is employed; thus rendering the collection highly instructive. This remark equally applies to the other building stones in the Museum.

Among the sandstones are exhibited several specimens of Millstone Grit. This is the name given to a series of sandstones interposed, in certain districts, between the Carboniferous Limestone and the Coal Measures. In the north of England, where the grit is typically developed, it occurs as a coarse sandstone, in which the quartz frequently appears as large pebbles, sometimes even reaching the size of an egg. From the position of the millstone grit, immediately beneath the true coal-bearing rocks, it is not inappropriately called by the miners in some of our south-western coal fields, the "Farewell Rock."

Limestones

Cubes in Table Cases V. and VI. Copy of the Farnese Hercules in Portland Stone, No. 81.

Limestones of several characters, from widely different localities, are here gathered together. Most of these are derived from hassle and oolitic rocks, since palaaozoic limestones, are for the most part, sufficiently indurated and compact to receive a polish, and may therefore be classed as marbles rather than as ordinary limestones; whilst on the other hand, the limestones of the upper cretaceous beds are usually too soft for building purposes; chalk, however, is employed in some districts to a considerable extent.

The lias formation, as it is called,—the term being probably a corruption from layers, as indicating the mode of occurrence of its beds—extends over a great length of. England, stretching in a north-easterly direction from near Lyme Regis, on the Dorsetshire coast, to Redcar, on the coast of Yorkshire. The lias limestones—which are often of a blue tint—are usually more or less argillaceous, and form, when burnt, a valuable hydraulic cement : whilst the finer stones are used not only as building materials, but also as paving slabs. Some of the lies limestones strongly resemble those employed for lithography; the true lithographic stones are obtained from the oolites of Solenhofen, in the Bavarian Jura, a short distance from Munich.

Immediately succeeding the lias is the great group of Oolitic rocks which traverse England from the extremity of Yorkshire to the coast of Dorsetshire, in many places affording enormous quantities of excellent building material.

The name "oolite" (tap, don, an egg; xisos, lithos, a stone) is derived from the limestones of this group, being, for the most part, made up of small egg or roe-shaped particles, which are spheroidal concretions of carbonate of lime; each grain usually presenting a concentric structure, and enclosing a particle of sand, or some other substance which has served as a nucleus. It should, however, be remembered that all the limestones belonging to the oolite-series do not present this peculiar texture; nor, on the contrary, is this oolitic structure confined to rocks of this formation, many of the palmozoic limestones in certain districts being lithologically true oolites.

From the Great Oolite Limestone is obtained the celebrated "Bath, stone," the principal quarries of which are those of Box, Coombe Down, Monekton, Farleigh, and Corsham Down. In the restoration of Henry the Seventh's Chapel the Coombe Down stone was employed, costing about 40,000l.

Bath stone possesses an agreeable warm tint, is worked with great ease, and may be obtained in blocks of large size; but unfortunately it does not possess great durability when exposed to the atmosphere of large towns. It is, however, extensively employed for ornamental mouldings and sculptured decorations. One peculiarity connected with this and other free-working limestones is that they become in some degree harder on their surfaces by exposure to the weather. This is said to arise from a slight decomposition taking place, which will remove most of the softer particles, and leave the hardest and most durable to act as a protection to the remainder.

The valuable Portland stone is derived from the upper oolites of the island of Portland, near Weymouth. The quarries from which the stone is obtained,—of which there are at least fifty,—are principally at the north end of the- island. The conditions under which the Portland stone, with the overlying Purbeck beds, occurs will be best understood from the following account of the beds, abstracted from that given by Mr. Webster.— (Observations on the Purbeck and Portland Beds.)

Immediately under the soil is a series of thin beds, about three feet thick, called slate by the quarrymen, consisting of limestone of a dull yellowish colour. Below this is another mass of calcareous stone, of a softer and lighter colour; it is divided into two by a slaty bed, the upper being called aish, and the lower the soft burr. These are between four and five feet thick.

Below this -is the dirt bed, about one foot thick, which consists of a dark brown substance containing much earthy lignite. In it are found considerable numbers of the fossil trunks of coniferous and cycadeons trees, of which a fine specimen will be found in the N.E. corner of the Hall (No. 53).

A limestone rock, ten feet in thickness, then occurs, which is called the top cap, and below that another, distinguished by its cellular character, and known as the school cap, which is about three feet thick. Under the school cap is a layer six inches thick of flint or chert.

The bed below this is the first which is worked for freestone, and is called roach. Its thickness is variable, being in the mean about fifteen feet. This is the most valuable bed, and blocks of a vast size are raised from it for the London market. Below the roach is the rubbly bed, which is not of much commercial value; this is about five feet thick, and underneath it another good bed of freestone, about six feet on the average in thickness, called the white bed, or best bed. This lower bed is worked whenever it is found in convenient situations.

Previously to 1623 this stone does not appear to have attracted any attention. From 1660 it has gradually grown into use. Inigo Jones restored a portion of Old St. Paul's, "casing great part of the outside, and adding a grand Corinthian portico to the west front, all of Portland stone." St. Paul's Cathedral, and many of the churches and other large buildings erected in the reign of Queen Anne, were constructed with stone very superior to that now generally employed, as far as regards durability. The quarries from whence Sir Christopher Wren obtained the Portland stone which he employed have been long deserted, the only reason assigned being that the merchants find that they cannot sell that stone on account of its being a little harder, and thereby more expensive to work.

No. 47, placed under Case IX. is a large fossiliferous slab of Portland stone from Tisbury, in Wiltshire; and a fine specimen of Ammonites giganteus, No. 82, a characteristic fossil of these beds, will be found at the base of the statue of Hercules.

Overlying the Portland series are the fresh-water beds of the Purbeck group, so called from the district known as the Isle of Purbeck in Dorsetshire, where this formation is well exhibited. From the upper beds of this group is obtained a compact shelly fresh-water limestone known as Purbeck marble, of which a specimen is exhibited in Case I. The marble abounds in organic remains, and indeed is a congeries of fresh-water snail shells (Paludinæ), intermixed with the shells of some minute crustaceans. It occurs in beds which vary in thickness from six to nine inches; and it was much employed formerly in this country for making the slender shafts in Gothic churches; but the introduction of foreign marbles has occasioned its use to be almost discontinued.

Very similar to this Purbeck marble are the fresh-water limestones occurring in thin local bands in the Weald clay, and known as Petworth, or Sussex, marble. They abound in casts of paludinæ, but of a species different from that which characterizes the Purbeck limestones.

The Kentish rag, of which a specimen is exhibited in Case VI., from the Iguanodon Quarry, near Maidstone, is a hard siliceous limestone from the Hythe beds of the lower greensand, where it occurs associated with a soft calcareous sandstone known locally as "hassock." The rag stone is extensively used for building purposes, the total quantity shipped being about 55,000 tons per annum (Descriptive Catalogue of Rock Specimens, 3rd ed., p. 152).

Although British building stones' alone are, as a rule, admitted into the collection, an exception is made in favour of the celebrated Caen stone, a cube of which is placed in Case V. This Norman oolite, which is an equivalent of our Bath stone, was held in high repute by the architects of the middle ages, and was largely employed in this country. Amongst the buildings in which it was used may be specially noticed the Temple Church, and Winchester and Canterbury Cathedrals..

Dolomites. Magnesian Limestones

The stone employed in the building. The Giustiniani Minerva, eastern side of Hall No. 37. Antinous as Bacchus, No. 58. Cubes in Case VI.

The Dolomites,—so called because they were first examined by the French geologist, Dolomieu,—are essentially limestones in which the carbonate of lime is replaced to a greater or less extent by carbonate of magnesia. These magnesian limestones are largely developed in the Upper Permian beds of the north-east of England, where they often exhibit peculiar concretionary structures, of which examples will be found in the collection of rock specimens in the upper gallery. As building materials the magnesian limestones are highly important, well selected varieties being exceedingly durable, especially when presenting a crystalline texture, and containing the carbonates of lime and magnesia in nearly equivalent proportions.

The more important quarries from which the magnesian limestone is obtained are those of Ruston, of Brodsworth, Cadeby, and Park Nook, near Doncaster, of Huddlestone near Sherburne, and of Smawse near Tadcaster, in Yorkshire; while in Derbyshire the same stone of fine quality is obtained at Bolsover near Chesterfield, and in Nottingham at Mansfield Woodhouse. An analysis of Bolsover stone gave :—

Carbonate of lime	51.1
Carbonate of magnesia	40.2
Oxide of iron and alumina	1.8
Silica	3.6
Water and loss	3.3
	100.0

The specific gravity of a dry mass of this stone is 2.316. The weight in the ordinary state of a cube of two-inch sides, 4890`8 grains; the weight of the same stone when well dried, 4881.4 grains; when saturated with water it weighed 5,042 grains. This is an important consideration in the selection of any building stones. One specimen from Cadeby absorbed one-fourth of its bulk of water. A stone absorbing much water is liable to disintegration, when, during frost, this fluid consolidates. M. Brard introduced an experiment for determining the effect of frost on stones, which was highly recommended in France. The exact mode of experimentalising is tO dip measured samples of stone into a boiling solution of Glauber's, salts, and leave them in it exactly half an hour. They are then removed and hung up, each by itself, over a vessel containing some of the above cold saturated solution. Within 24 hours a white efflorescence will appear on the surface. The stones must then be immersed in the liquor in the subjacent vessel, so that the crystals disappear. Whenever the efflorescence forms, the stone is to be thus treated. It is said that the tendency to disintegration in any stone will be shown by this treatment. By such an experiment, continued for eight days, the Bolsover stone disintegrated to the extent of one grain and a half. It was, however, shown by the late Mr. C. H. Smith that this process differs materially from the action of frost, which it is intended to imitate, since the crystallization of Glauber's salt is unaccompanied by that expansion which attends the freezing of water; indeed, many highly durable stones disintegrated under this treatment to a much greater extent than other stones well known to decay rapidly on exposure.

In some of the chemical works on the Tyne the dolomites of the northern counties are used for the production of carbonate of magnesia; while the magnesian limestones of Marsden are taken in considerable quantities to Sunderland, where, being treated with sulphuric acid the magnesia is dissolved out, and from the liquor obtained, Epsom salt, sulphate of magnesia, readily crystallises. A considerable proportion of the Epsom salts now sold is thus obtained.

Grinding and polishing stones

Case VIII

There are tolerably numerous varieties of materials which are used for the purpose of giving fine edges to cutting instruments, or a polish to metal and other surfaces. The collection in this case, mostly presented by the late Mr. R. Knight, is intended to illustrate this class.

Newcastle grindstones are very celebrated; it is proverbially said they are found everywhere. They are formed from sandstones which abound in the coal districts of Northumberland, Durham, Yorkshire, and Derbyshire. According to the varying degrees of density and coarseness they are employed, especially in Birmingham and Sheffield, for grinding or for giving a smooth and polished surface to their different wares.

At Bilston, in Staffordshire, is found lying above the coal a peculiar sandstone, finer than the above, and of a very sharp nature. This is quarried entirely for the Bilston grindstones, which are of great excellence.

The carpenter's millstone is a hard and close variety of the Yorkshire sandstones. The northern counties yield several varieties of grindstones, which are much in request for different descriptions of work. Yorkshire grit, for example, is used for polishing marble and the copper plates for engravers. The Sheffield grindstone is a hard and coarse stone used for common purposes; it is found at Hardsley, 14 miles north of Sheffield. The Sheffield blue stone is a fine-grained stone, used for finishing fine goods. The act of grinding on a blue stone is termed "whittening"—the Sheffield whittle from the earliest periods being in all probability ground on this stone. Wickersley stones are obtained about nine miles from Sheffield, and are much used by the cutlers for grinding.

Devonshire bats are in much repute. These are porous fine-grained sandstones found in the quarries of Black Down Cliff, near Collumpton.

Hone Slates.—These are slaty stones used in straight pieces for sharpening tools after they have been ground on revolving grindstones. The more important varieties are the following:—

The Norway ragstone, which is the coarsest variety of the hone slates, is imported in large quantities. from Norway. In Churn-wood Forest, near Mount Sorrel, in Leicestershire, particularly from the Whittle Hill quarry, is obtained the Charnley Forest stone, said to be one of the best substitutes for the Turkey oilstone, and it is much in request by joiners and others. Ayr stone, snake stone, and Scotch stone are used especially for polishing copper plates. The Welsh oilstone is almost in equal repute with the Charnley Forest stone; it is obtained from the vicinity of Llyn Idwal, near Snowdon, and hence it is sometimes called Idwal stone. From Snowdon is also obtained the cutler's green stone. The Devonshire oilstones, obtained near Tavistock, which were introduced by Mr. John Taylor, are of excellent quality, but the supply of them being irregular, they have fallen into disuse.

The German razor hone has been long celebrated. It is obtained from the slate mountains in the neighbourhood of Ratisbon, where it occurs in the form of a yellow vein running through the blue slate, varying in thickness from one to eighteen inches. When quarried it is sawn into thin slabs, and these are generally cemented to slices of slate which serve as a support. Sometimes, however, the yellow and the blue slate are cut out naturally combined. There are several other hone stones, which, however, require no particular notice.

The Turkey oilstone is said to surpass in its way every other known substance, and it possesses in an eminent degree the property of abrading the hardest steel; it is, at the same time, of so compact and close a nature as to resist the pressure necessary for sharpening a graver, or any instrument of that description. There are white and black varieties of the Turkey oilstone, the black being the harder, and it is imported in somewhat larger pieces than the white; they are found in the interior of Asia Minor, and brought down to Smyrna for sale.

Among the examples of mineral substances employed as burnishers will be found a specimen of agate (p.129), and a piece of haematite or red iron ore (p. 102); the latter mineral, although exhibited under the name of blood stone, is to be carefully distinguished from the "blood stone" of the jeweller (heliotrope), which is a jaspery variety of silica to be subsequently noticed (p. 142).

The corundum and emery exhibited in this case are varieties of alumina, a mineral which is presented in its purest form in the ruby and sapphire; and which will again be met with in the horseshoe case on the principal floor (p. 143).

Emery is obtained from Cape Emeri, in the island of Naxos, and from several localities in Asia Minor; it occurs also in Jersey and Guernsey, in Poland, Saxony, Sweden, and Persia, and some large discoveries have lately been made in Chester, Massachusetts. From its excessive hardness it is used for polishing, for which purpose it is prepared by grinding and eleutriation, and then sold under the name of flour of emery. The hardness of the Indian sapphire being considered as 100, that of corundum is 77, and that of the emery of Naxos, 46.

In addition to those polishing stones which have been especially mentioned, there will be found on the opposite side of the case a series from France. The celebrated "Burr Stones" of La Ferte-sous-Jouarre (Seine et Marne) are unequalled for grist mills. The combined roughness and hardness of this tertiary quartz deposit give it immense advantages, expensive though those stones are, in consequence of the necessity of carefully piecing them together.

The trachytic lava from the extinct volcanos of the Lower Eifel furnishes millstones which have long been justly celebrated. They were well known to the Romans, and are still extensively quarried at Niedermendig, near Andernach, whence they are sent down the Rhine to Holland, and exported to most parts of the globe. Under the name of "Dutch Blue Stones" they were formerly much used in this country.

From Milo, in the Grecian Archipelago, are exhibited some trachytic millstones, which are not only extensively used in Greece, but are also largely exported to Turkey and Trieste.

In the same ease are several varieties of the hone slates from Cornwall, but the hones from the Cornish slates have not, as yet, come into anything like general use.

The Talacre scythe stones are formed from the millstone grit of the Flintshire coal-field, on the estate of Sir Pyers Mostyn, Bart. From Gronant, near Talacre, is exhibited in Case VII. a specimen of chert, which occurs in the Mountain Limestone, and is almost exclusively employed in the Staffordshire Potteries for grinding flints.

Gypsum. Plaster of Paris. Cements

Case IX. Cast of Apollo Belvedere, 111; of Dying Gladiator,156; of Greek Vase, 91; and of Armour, 15. Pavement in Keene's Cement, 76. Benson and Logan's Cement, 97. Septaria, 65, 72, 116; and in Case VII.

The well-known mineral Gypsum is a hydrous sulphate of lime occurring abundantly in the New Red or Keuper Marls, often associated with rock salt. When transparent and crystallized, it is known as selenite, and when fibrous, as satin spar; specimens of both varieties will be found in this case. The fine semi-crystalline form of gypsum termed Alabaster has been already noticed as an ornamental stone (p. 26). All these substances are natural hydrates; but the mineral called Anhydrite, of which a specimen is exhibited from Derbyshire, is a pure sulphate of lime, destitute of any essential water, its composition being, lime, 41.18; sulphuric acid, 58.82.

When gypsum is calcined at a moderate temperature it parts with the whole of its water, and has then a composition resembling that of anhydrite. This calcined gypsum when reduced to powder forms the well-known Plaster of Paris, of which three qualities are exhibited. This name is derived from the circumstance that the mineral from which the plaster is obtained is found in abundance in the tertiary deposits of what is called the Paris basin, especially at Montmartre. Mixed with sufficient water to convert it into a paste, gypsum eagerly absorbs the liquid, and, returning to its original hydrated condition, rapidly solidifies or sets. lf, however, the gypsum be overburnt this setting is prevented, and in practice to ensure rapid consolidation, it is often desirable not to expel the whole of the water from the mineral. A certain amount of impurity in the original gypsum appears to operate favourably rather than otherwise, the superiority of the French plaster of Paris, which acquires a greater degree of solidity than any other, being referred to its containing about 12 per cent. of carbonate of lime. M. Gay Lussac says that the purest plasters are those which harden least; he does not, however, consider this to depend upon the presence of the carbonate of lime, but on the original hardness of the stone.

The aggregate annual consumption of gypsum in this country has been estimated at 30,000 tons, valued at 10,0007. The largest quantities of plaster of Paris are used in the Potteries, the potters employing it to form their moulds.

The facility with which, by means of plaster of Paris, copies of any objects can be obtained, renders it of great value in multiplying the finest works of ancient and modern art. Some extraordinary applications are shown in the copy of a cup by Benvenuto Cellini in the case, and by fac-similes of ancient armour, No. 15, which are hung upon the wall against the eastern staircase. The colour in these examples is given by rubbing bronze powder over the surface of the dry plaster.

One interesting process is shown in which the gypsum is heated to expel nearly all the water; it is then tinted with colour, and subsequently re-saturated with water.

Fictile ivory, of which there are several examples, is plaster of Paris, which, after drying, has been made to absorb melted spermoceti by capillary action; or it may be prepared according to Mr. Franchi's process as follows :—Plaster and colouring matter are employed in the proportions of a pound of superfine plaster of Paris to half an ounce of Italian yellow ochre. They are intimately mixed by passing them through a. fine silk sieve, and a plaster cast is made in the usual way. It is first allowed to dry in the open air, and is then carefully heated in an oven; the plaster cast, when thoroughly dry, is soaked for a quarter of an hour in a bath containing equal parts of white wax, spermaceti, and stearine, heated just a little beyond the melting point.. The cast on removal is set on edge, that. the superfluous composition may drain off, and, before it cools, the surface is brushed, with a brush like that known by house painters as a sash tool, to remove any wax which may have settled in the crevices; and finally, when the plaster is quite cold, its surface is polished by rubbing it with a tuft of cotton wool.

Some casts, as will be, seen, are in very high relief.; these are made in elastic moulds,—a composition of glue and treacle, which admits of being turned out from the "under cutting" without injury. This process enables any one to copy and preserve the gems of ancient and modern art in a material which is at once pleasing and moderately durable. Ancient ivories can be exactly imitated by the introduction of a little more colour, or by painting the plaster in water-colours before it is dipped into the composition.

By subjecting plaster of Paris to certain methods of chemical treatment, it may be hardened to a considerable extent, and thus becoming much less liable to injury, its value as a cement is greatly increased. Many of these processes of hardening are illustrated in the collection.

Keene's cement, according to the specification, is thus prepared :—Dissolving one pound of alum in a gallon of water, this solution is used for soaking 84 pounds of gypsum calcined, in small lumps. These lumps are then exposed for eight days to the air, and afterwards calcined at a. dull red heat.

They are then ground and sifted. The fine powder thus produced is mixed with water into a paste, which may be employed as ordinary plaster of Paris; upon setting, it forms a body of great compactness and durability, which can be polished or coloured without difficulty. If half a pound of proto-sulphate of iron (the common copperas) be added to the solution of alum, the resulting paste has a fine cream colour, and the hardened mass is said to resist the action of the atmosphere.

The Parian cement is prepared by soaking the plaster in a solution of borax instead of one of alum. This is exemplified in the cast of the "Dying Gladiator" and its base, as well as in the coloured cement on the stairs, in which Derbyshire marbles, to be found in the collection, are imitated, for the purpose of showing to what extent the realization of a natural stone can be secured in an artificial one. Martin's cement is formed by combining pearl ashes (bi-carbonate of potash), and alum with the plaster, hydrochloric acid being sometimes added to prevent an alkaline re-action.

Scagliola differs from all these cements, in consisting of small fragments of marble, and other ornamental substances, embedded in a base formed of a mixture of plaster of Paris and glue. This was the invention of Guido del Conte, an ingenious mason of Cari, near Corregio, in Lombardy. Scagliola was much employed by the Florentines in some of their most elaborate works.

Roman cement is made from the septaria, or "turtle stones," which occur abundantly in many beds of clay. Great quantities of these cement-stones are at present procured by dredging off the coast of Hampshire for the septaria which have been derived from the Barton clay. They are also found largely at Harwich and in the Isle of Sheppey, and are dredged up in Chichester harbour, where they are derived from the London clay. Some typical specimens are exhibited in Case VII.

A septarium is simply a nodule of argillaceous limestone, often containing in its interior an organic substance, serving as a nucleus around which the limestone aggregated. The contraction suffered during dessication has produced fissures, or cracks, which have subsequently been filled by deposition of carbonate of lime. These veins of calcite being disposed with tolerable regularity through a darker base, produce, on section, a peculiar pattern, which is well seen in the polished slabs, Nos. 65 and 72.

The cement-stones are calcined in kilns, then ground, sifted, and packed in casks. The cement so prepared possesses the valuable property of rapidly hardening under water, a property which appears to be due to the presence in the septaria of certain adventitious ingredients, especially silicate of alumina. The following may be taken as an average analysis of the English cement-stones yielding this hydraulic mortar :—

Carbonate of lime, 65. 7; protoxide of iron, 6.0; silica, 18.0; alumina, 6.6.

Benson and Logan's metallic cement is a compound of the ground slag from the copper-smelting works at Swansea with ordinary cement-stone. A sketch painted in colours on a ground of this peculiar cement will be found on the western wall (No. 97). Near this is placed a stereo-chromatic painting on baked clay (No. 104), illustrating the application of alkaline silicates to the fixing of colours on exterior walls. The clay, or other substance serving as the painting ground, is prepared by impregnation with a solution of an alkaline silicate, or "water glass," and a surface is thus obtained, to which the colours readily adhere. The painting, which may be executed with perfect freedom unlike the ordinary mode of fresco painting, is finally fixed by a coating of water-glass, which effectually preserves it from the action of weather, even in the most exposed situations. The specimen before us is by Eohter of Munich, after a design by Xaulbach.

In Case VII. will be found some specimens of artificial stone, prepared by Mr. Fred. Ransome, of Ipswich. This gentleman has at different times patented several processes for this purpose, but the general principle consists in using water-glass as a cement, by which sand is formed into a compact stone, remarkable for its high cohesive power.

By the side of this artificial stone are some specimens of flints which have been acted upon by heated carbonate of soda in the preparation of the alkaline silicate employed by Mr. Ransome.

Tesselated pavements

Centre of Hall. Slabs, Nos. 76 and 90.

The design of the fine specimen in the centre of the hall has been taken from various tesselated pavements found, during 1793, 1794, and 1795, in the remains of a Roman villa discovered at Woodchester in Gloucestershire. A particular description of this will be found in Samuel Lyson's Woodchester Antiquities. Some additional examples of mosaic pavements will be found connected with the specimens of ancient and modern mosaic on the principal floor (p. 72).

The tesseras of which the pavement is formed, and the encaustic tiles by which it is surrounded, were manufactured by Messrs. Minton & Co. of Stoke-upon-Trent. The process of manufacture is an interesting one. Mr. Prosser invented a machine for compressing clay, which has been employed by Messrs. Minton & Co. Porcelain clay, either white or with an admixture of colouring material, is taken in what we may call a dry state, the clay containing only its hygroscopic water; it is placed in moulds the sizes and shapes of the required tesseraz or tiles, and, being subjected to pressure, its particles are brought so closely together that they readily cohere, and the whole comes out a solid piece. For the purpose of giving the greatest degree of hardness to it, it is subsequently exposed to heat, when the materials for the formation of the mosaic are ready for use. Another variety of the same manufacture will be seen still nearer the entrance. These pavements are exceedingly durable, and in many situations possess advantages over every other kind of flooring, irrespective of the artistic beauties of which they admit. The tiles are of the same general character; a variety of these will be found with the pottery collection in the upper room.

Crucibles, Clay and Black Lead

Case X.

Here will be found examples of the application of clays to the manufacture of melting pots and crucibles. As these vessels have to be exposed to the intense heat of furnaces, it is important that such clays should be selected for their manufacture as are very infusible. Such as contain much potash, lime, or other bases, readily fuse into a semi-vitreous mass; but, on the contrary, those which contain a large proportion of silica are highly refractory. To diminish the contraction and expansion which clays undergo on exposure to sudden changes of temperature, as also to increase their infusibility so that colapse of the crucible may be prevented, the clays are generally mixed with certain infusible materials, such as free silica in the form of sand, ground fragments of old crucibles, and finally powdered coke or graphite.

The chief commercial varieties of crucibles are represented in this case, the greater portion having been acquired from the Great Exhibition of 1851.

With the crucibles is exhibited a small collection of fire bricks, among which may be specially noticed the valuable Divas brick, formed of a highly siliceous rock occurring in the Vale of Neath in Glamorganshire, and known locally as "Dinas clay." The powdered rock, mixed with a small proportion of lime to act as a flux, is moulded into bricks, which are highly refractory, and are hence largely employed for lining copper-smelting furnaces. For further information on this, and on the contents of this case generally, see Dr. Percy's Metallurgy, Vol. 1.

Basalt.—Columns from the Giant's Causeway, No. 42

These specimens well illustrate the peculiar columnar structure which basalt very frequently assumes, and on which depends the characteristic scenery of the Giant's Causeway, the Isle of Staffa, and other well-known basaltic districts. The basalt of which these are composed is a dark-coloured, fine-grained igneous rock, composed .of an intimate mixture of felspar, usually labradorite, and augite, often associated with certain adventitious minerals, as olivine, magnetic iron, &c. The columns, as seen by the specintens exhibited, are large six-sided pillars, each prism_• being Usually terminated by a convex face at one end, and a corresponding convexity at the other; and by a kind of ball-and-socket joint thus formed, the individual columns are articulated.

The columnar structure of the basalt has been artificially produced.. Mr. Gregory Watt melted seven hundredweight of basalt, and kept it in a furnace several days after the fire was reduced. It fused into a dark-coloured vitreous mass with less heat than was necessary to melt pig iron. As refrigeration proceeded the mass became stony, and globules appeared; these enlarged till they pressed laterally against each other, and became converted into polygonal prisms.

In Case VII. are some examples of the application of a basaltic rock, after it has undergone fusion, to decorative and ornamental purposes. Messrs. Chance, Brothers, of Birmingham, adopted the process of melting the Rowley rag, a basaltic rock forming the plateau of the Rowley hills, near Dudley, South Staffordshire, and then casting it into moulds for architectural ornaments, tiles for pavements, &c. Not only the Rowley rag, but greenstone, whinstone, or any similar rock may be used. The material is melted in a reverberatory furnace, and when in a sufficiently fluid state is poured into moulds of sand encased in iron boxes, these moulds having been previously raised to a red beat in ovens suitable for the purpose. The object to be obtained by heating, the moulds previous to their reception of the liquid material is to retard the rate of cooling; as the result of slow cooling is a hard, strong, and stony substance, closely resembling the natural stone, while the result of rapid cooling is a dark brittle glass, similar to obsidian.

Large mass of native copper from the Mine at the. Ghostcroft, Mullion, Cornwall

No. 165.

Trenance mine, from which this remarkable specimen was obtained, was worked near Mullion, close upon the junction of the serpentine with the hornblende-slate rocks.

It is not unusual to find, in the fissures of the serpentine rocks, masses of native copper; these have frequently induced a further search for mineral treasure, which has rarely been successful. In Trenance mines numerous deposits of a similar character to the specimen exhibited were found, and, consequently, it was hoped that a profitable copper mine might have been opened. out; this hope was, however, not realized, and the mine was abandoned about twelve years since. The specimen, which was presented .by the adventurers, is only a portion of the mass as it occurred in nature; the miners being compelled to break it to raise it to the surface.

Part of a Lead vein or lode from the Grassington mines

No. 166.

The Grassington mines, the property of the. Duke of Devonshire, by whom this fine, specimen was presented, are the most important in Yorkshire. This example shows in a very instructive manner the mode in which, ordinarily, lead occurs in nature. By looking at the transverse section, which hangs upon the north side of the stand supporting it, it will be seen that the strata in which this lode occurs have been dislocated,—that the beds have lost their regularity; the result of this being a fissure running nearly _vertical through all the beds. In this crack the mineral deposit has taken place. The mineral here formed is the sulphide of lead, or galena (p. 100). The regularity observed in the order in which this fissure has been filled in with the mineral matter points to a process in nature analogous to that of the electrotype, in art; but it would be hasty to conclude, without more evidence than experiment has at present given us, that mineral lodes were entirely due to the exercise, of electrical force. Further remarks upon this pOint will be found in connexion with the principal collection of lode specimens at p. 90.. The produce of the Grassington lead mines for the year 1865 was 535 tons, 4 cwts. of ore, producing 349 tons of lead. (Mineral Statistics.)

Portion of a vein of gold-bearing quartz

No. 103.

The discovery of gold in California, in June 1848, produced an extraordinary amount of excitement in this country and in the United States; within six months 5,000 persons were attracted to this remote region. The gold from the deposits in the beds of the tributaries running into the Sacramento, and in the alluvial valleys of the country, becoming, •from the eager search which was made for it, unequal to the desires of the adventurers, the quartz lodes, which were discovered in the rocks, became the objects of exploration. Numerous mines were opened, and workings commenced upon an extended scale; these have not, however, been remunerative speculations. In the quartz-veins gold is found, and sometimes in considerable quantities; but it is exceedingly uncertain. The specimen exhibited is from the Grass valley, Nevada county, and was presented.by the late Mr. F. Catherwood : it fairly represents all the average conditions of the gold-bearing quartz-lodes, not only of California, but of Australia and other countries. Small particles of gold are here and there visible, and some gold is disseminated through the mass, but so finely divided as to be invisible. Some richer fragments of gold-quartz are in the same case. The quantity of gold produced in California is stated at one period to have reached the enormous sum of 15,000,0001. (See Lectures on Gold, delivered at the Museum of Practical Geology.)

Busts

Her Most Gracious Majesty The Queen, Executed by Francis, 1850. No. 204. H.R.H. The late Prince Consort. Executed by Francis, 1843. No. 170.

These being cast in zinc, are subsequently bronzed, and are examples of the application of an inexpensive material in the production of works of art.

The busts of eminent men, who have advanced the science of geology, form appropriate and interesting features in this Hall..

James Hutton, M.D.

An original bust by Patric Park. No. 74.

James Hutton was born 3rd June 1726 at Edinburgh, which University he entered as a student in 1740. Dr. Hutton devoted much attention to agriculture; and when seeking information on rural economy, he appears first to have acquired a taste for mineralogy, and, as he himself expresses it, "became remarkably fond of studying the surface of the earth."

In 1777, Dr. Hutton gave to the world his first publication, "Considerations on the nature, quality, and distinctions of Coal and Cuba." During 30 years Dr. Hutton's attention was turned to geology, and this led him to communicate to the Royal Society of Edinburgh his "Theory of the Earth," that most remarkable and original work, which was in truth the foundation of modern geology. This was subsequently published in two volumes. Dr. Hutton died in 1797, and of him it is said:— "The greatest acquisitions of wealth and fortune never excited more lively sensations of pleasure in the minds of men, than those which arose in the mind of Dr. Hutton on hearing of a new invention, or on being made acquainted with a new truth." "He would rejoice over Watt's improvements on the steam engine, or Cook's discoveries in the South Sea, with all the warmth of a man who was to share in the honour or the profit about to accrue from them."

William Smith, LL.D

An original bust by M. Noble. No. 68.

William Smith was the author of the first geological map of Eng. land and Wales. He was born 23rd March 1769 at Churchill in Oxfordshire, and died 28th August 1839 at Northampton. At an early period, being employed to make careful surveys of collieries in Somersetshire, he was much struck with the constancy of the order of superposition of the strata; and this appears to have led him to a general examination of the country. In 1794 Mr. Smith was enabled, by one long journey through great part of England and Wales, to commence his "Geological Map of England and Wales," and to draw up a "Table of the Superposition of the Strata." It was not until 1815 that those labours were fully developed, when he published a "Delineation of the Strata of England and Wales," and a memoir on the subject. In 1831 the Geological Society of London awarded to Mr. W. Smith their Wollaston medal "in consideration of his being a great original discoverer in English geology, and especially for being the first, in this country, to discover and to teach the identification of strata, and to determine their succession by means of the imbedded fossils."

Professor J. Playfair

After Sir F. Chantry by M. Noble. No. 220.

John Playfair was born at Benvie, in Forfarshire, March 10, 1748. Dr. Wilkie, the Professor of Natural Philosophy at St. Andrews, finding himself unable to discharge the duties of his office, delegated them to Playfair, then a student; this fact proves the estimation in which he was then held. In 1773 Playfair obtained the living of Liff and Benvie, and in 1779 he communicated his first paper to the Royal Society of London. In 1785 he was appointed Professor of Mathematics, jointly with Dr. Ferguson, in the University of Edinburgh; and on the death of Mr. Robinson in 1805 he succeeded him to tho chair of Natural Philosophy in that university. He was the intimate friend of Hutton and the strenuous supporter of the geological theory which bears that philosopher's name. Playfair's "Ilustrations of the Huttonian Theory of the Earth" have been much admired for the clearness with which the system was unfolded. His works were of a miscellaneous character, chiefly connected with mathematics and the higher branches of natural philosophy. The death of Professor John Playfair took place at Edinburgh on the 19th July 1819.

Sir James Hall

An original bust by Patric Park. No. 218.

James Hall.—There were few men who united with more advantage chemistry and geology than Sir James Hall. At the period when the theories of the earth's formation were zealously discussed, Sir James Hall was induced to make some experiments of a very important character in connexion with the subject.

The results of these investigations will be found in the Transactions of the Royal Society of Edinburgh. Sir James Hall died in 1832; and as an attentive geological observer, and a zealous chemical experimentalist, his bust finds its appropriate place with the men of his time, Playfair and Hutton.

Professor Edward Forbes

An original bust by I. C. Lough, 1856. Presented by subscription. No. 155.

Edward Forbes was Palaeontologist to the Geological Survey of the United Kingdom, and teacher of Natural History in the Government School of Mines. He was born in the Isle of Man in 1815.

Edward Forbes was a naturalist from his childhood, always delighting in the works of creation spread around him : he spent some time at the University of Edinburgh, and in 1833 he travelled with a fellow student to Norway. Eight years after this he was appointed naturalist to a surveying expedition to the Mediterranean. With Captain Graves, in H.M.S. "Beacon," he proceeded to the scene which he has marked by his important labours. In the ./Egean he was enabled to determine some remarkable facts connected with animal life in the ocean, and to carry out those dredging explorations which enabled him subsequently to deduce some important considerations on the distribution of animal life in space and time. During this appointment he travelled in Lycia, and fixed the sites of several of the Cibyratic cities. In 1843 Edward Forbes was appointed Professor of Botany in King's College. He shortly after became Secretary and Curator of the Geological Society, Palæontologist to the Geological Survey, and, on the organization of the Government School of Mines, its Professor of Natural History. To the Memoirs of the Geological Survey Professor E. Forbes contributed several valuable papers; and under his care was commenced the publication of the Decades, illustrative of British organic remains.

On the death of Professor Jameson, the Regius Professor of Natural History in the University of Edinburgh, Professor Edward Forbes was appointed to succeed him. This chair was the object of Forbes's ambition, but he was not destined long to enjoy it; for he died on the 18th of November 1854, only six months after his appointment.

Professor Edward Forbes's latest work, of which he left an outline sketch at the time of his death, "On the Tertiary Fluvio-Marine Formation of the Isle of Wight," has been completed by his colleagues, and published as one of the Memoirs of the Geological Survey..

Sir Henry Thomas De la Beche, C.B.

From a bust by M. L. Watson. No. 212.

Another bust in bronze, presented-by Mr. E. H. Baily, R.A., is placed in the Library of the Institution.

This eminent geologist, the founder of this institution, was born in 1796. Losing his father at an early age, he resided for some years with his mother in Devonshire, then at Charmouth,- and afterwards at Lyme-Regis. To his early associations may be referred those studies which became the business of his life; and it in interesting to witness the love with which he always returned to the consideration of the rocks of Western England, amongst which in his boyhood he had rambled; always finding, never seeking, pleasure. In 1810 Henry De la Beche entered the Military School at Great Marlow; but he never embraced the profession of arms, and in 1817, entering the Geological Society, he enrolled himself in that select band, who were then struggling to establish geology as a science, and of which he soon became a guiding spirit, and .eventually the leader. Mr. De la Beche always exhibited great activity of mind, and numerous memoirs and other publications were continually proceeding from his pen.

In 1835 was commenced the great work of the Geological Survey of the United Kingdom, which may be regarded as one of the first scientific inquiries fairly recognized by the Government of this country. Mr. De la Beche was attached to the Ordnance Survey, with power to carry out a geological survey of the western counties, and to publish his results on the one-inch Ordnance maps, by geological colouring. Upon this important point the words of the present Director-General, Sir Roderick I. Murchison, spoken on receiving from the Geological Society the Wollaston medal for his friend, then in his last illness, are especially to the purpose :

At his own expense he traced the boundaries and relations of certain rock formations, and laying them down on the Ordnance Survey maps, accompanied by illustrative sections, he thus took the first step, in leading public men (otherwise little versed in our science) to see the good which must result from the extensive application of such a scheme, in making all proprietors alive to the importance of obtaining a better acquaintance with the subsoil of their estates.

Having gradually attracted the notice of the Government, and having obtained the use of rooms in Craig's Court, and the employment of a limited sum. of the public money, Sir H. De la Beche then attached to his new-formed establishment able men of science, who could decipher formations in the field, describe the fossils they contained, or chemically analyse the structure of the rocks and their associated minerals. Soon filling to repletion the small space allotted to him with models of mines, illustrative drawings, and specimens of fossils, ores, and building stones, he convinced, our rulers, and particularly the illustrious statesman Sir Robert Peel, that the dignity and interests of the country required an adequate and appropriate building should be erected, and exclusively devoted to the fulfilment of a project so lucidly devised, and thus far so well realized. Then arose, very much after the design of the accomplished director himself, that well adapted edifice in ,Jermyn Street, which, to the imperishable credit of its author, stands forth as the fast paktee ever raised from the ground in Great Britain by the Government, which is entirely devoted to the advancement of science.

Once possessed of halls worthy of so noble an object, Sir Henry De la Beche next rendered them practically useful to the public, and on a vastly extended scale, by embracing, as necessary adjuncts, metallurgy and mechanical science, in addition to the branches of knowledge previously cultivated."

For his zealous labours in the cause of geological science, the late Director-General of the Geological Survey was knighted by his sovereign. On the continent, too, the labours of Sir Henry De la Beche were fully appreciated; he was created a knight commander of the Danish order of Dannebrog, and of the Belgian order of Leopold; he was elected a corresponding member of the Institute of France, and a member of various foreign Academies.

On the 13th of April 1855 Sir Henry Thomas De la Beche died; his mental energies remained unimpaired to the last; thirty-six hours before his decease he visited the Museum, and spent upwards of an hour in carefully examining the results Of a statistical inquiry into the coal and iron produce of this country by the author of this Guide. This was the last public labour which engaged the attention of that mind, of which the Geological Survey, and the Museum of Practical Geology remain enduring monuments.

George Bellas Greenough, F.R.S.

An original bust by Neville Burnard, 1859, presented by the late Miss E. M. Smedley. No. 210.

George Bellas Greenough, the founder of the Geological Society, was born in 1778, and died at Naples in 1855. Intending to follow the legal profession, Mr. Greenough, after studying at Cambridge, proceeded to the University of Göttingen, where the attractions of Blumenbach's lectures on natural history induced him to abandon the law, and devote his energies to the pursuit of natural science. With this view he subsequently studied at the mining school of Freiberg, under the distinguished Werner, whose views he warmly espoused during the unhappy controversy between the Neptunists and Vulcanists. In the formation of the Geological Society of London Mr. Greenough took a most active part, and, in spite of the opposition offered by the Royal Society, his exertions were rewarded by its complete organization. As an appropriate honour to one who had so steadfastly supported its foundation, Greenough was elected the first president, a position which he continued to hold for several years.

Although possessing rich stores of information, accumulated during a long and zealous life, Mr. Greenough was not a great writer; but his profound acquaintance with the sciences of geology and geography is sufficiently attested by his valuable geological maps of England and Wales, and of India; the former published in 1819, and the latter in 1854, only one year before his death.

William Buckland, D.D., F.R.S.

A bust by H. Weekes, A.B.A., 1860. Presented by subscription. No. 152.

William Buckland was born at Axminster on the 12th March, 1784. His taste for geological pursuits appears to have been developed at an early age, for we find. him when a youth at Winchester College occupied in collecting the chalk fossils of the neighbour. hood, and on his subsequent removal to the University of Oxford the fossils of the oolites enabled him to pursue his favourite employment. At Oxford he attended the mineralogical lectures of Dr. Kidd, and on that gentleman's resignation in 1813 Buckland was appointed to the vacancy. About this time the importance of geological science began to be recognized at the university, and in 1818 a special readership in geology was founded, to which Dr. Buckland was advanced. His inaugural address on this occasion was afterwards published under the title of "Vindicim Geologim, or the Connexion of Religion with Geology explained." A few years later he gave to the world the interesting results of his original researches on bone caverns, in the form of a valuable treatise, entitled "Reliquim Diluviaum, or Observations on the Organic Remains in Caves, &c., attesting the action of an universal Deluge." Some of the views there maintained he was subsequently induced to modify, as seen in his later work, the admirable Bridgewater treatise on "Geology and Mineralogy considered with reference to Natural Theology." Dr. Buckland's zeal as a practical geologist and his ability as a writer are seen not only in these larger works, but also in the number of valuable papers which he was constantly contributing to the Geological Society. Towards the close of life, however, his mental activity rapidly declined, and after several years of retirement from geological pursuits, he expired on the 14th August 1856, having been Dean of Westminster for eleven years.

Principal Floor

The Staircase

On either side of the staircase, as we ascend from the Hall, are examples of metal castings;

In Iron, of

The Dogs of Alcibiades, cast by Moore, Fressange, and Moore.

A vase, designed by Edington, of Glasgow.

Candelabrum, from the French Exhibition of 1846.

Candelabra, cast by Moore, Fressange, and Moore.

Sleeping Dog, cast by Coalbrookdale Company,

Nymph and Sea-horse, cast by M. Durenne.

Hercules bending Ms Bow, cast by M. Durenne.

Diana attiring, cast by Moore, Fressange, and Moore.

Venus unrobing, cast by Moore, Fressange, and Moore.

In Zinc.

Eos, a favourite greyhound of H.R.H. the late Prince Consort, life size. In imitation of bronze. The original sculptured by Francis. Cast in zinc by Karl Schroder, London. Presented by the Vieille Montagne Company.

Principal Floor

Opposite the visitor is the figure of Galatea, executed in terra cotta by Messrs. Minton & Co., and presented by them. (See p. 58.)

At the corners of the opening from the lower Hall are—

A Vase after the Antique, by Wedgwood, presented by the late Apsley Pellatt. (See p. 56.)

A Vase, copied from the Antique, manufactured at Naples.

The Head of Ocean, No. 7, is at the foot of stairs on W. side. An electrotype in copper by Dr. Braun.

The Head of Melpomene, No. 51, at the foot of stairs on E. side.

An electrotype by Messrs. Elkington and Co.; presented by them. (See p. 120.)

Synopsis of the collection on this floor

POTTERY AND PORCELAIN.pp. 48 to 61.	The Ceramic series will be found arranged in the . embayments on the east and west of the stairs.The descriptions commence with the raw materials in the gallery on the right hand. or E. side, then proceed With pedestal cases 2, 3, 4, 5, 6, and Wall-cases on the left hand or W. side of the principal floor; and afterwards on the E. side, Wall-cases only. Foreign pottery, &c. in the gallery on the E. side.
GLASS, ANCIENT and MODERN.pp. 61 to 70.	Four cases in the-embayment on the E. side (Nos. 52, 53, 54, 55); and one of modern glass in the principal room (No. 47). Sheet and crown glass in the, gallery on the W. side.
ENAMELS. pp. 70 to 72.	Table-cases 1 and 56, on each side of the staircase from the hall; and the model of tomb of William de Vallence. No. 10.
MOSAICS. pp. 72, 73.	Table-ease 46, near the head of Melpomene. Specimens on walls of stairs to galleries: in Case 46 will also be found Babylonian Cylinder, 4e. 43:73).
BRITISH METALLIFEROUS MINERALS, OR ORES. pp. 74 to 81, and pp. 100 to 103.	In Wall-cases 1 to 14 on W. side, embracing, COPPER, 1 to 7; TIN, 8, 9; BISMUTH, COBALT, NICKEL, and WOLFRAM, 9; ZINC, 12; MANAGANESE, URANIUM, TITANIUM, VANADIUM, and and CHROMIUM, 13; ANTIMONY, GOLD, SILVER, ARSENIC, 14; and Wall-cases 43 to 50 on E. side, embracing LEAD, 43 to 45; and IRON, 46 to 56.
FOREIGN ORES. pp. 81 to 90.	Wall-cases on W. side from 15 to 23, embracing Canna, 15 to 17; IRON, 18, 19; MANGANESE, BISMUTH, MOLYBDENUM, URANIUM, TIN, COBALT, NICKEL, and ANTIMONY; 20; ZINC and LEAD, 21; SILVER, 22; GOLD,' PLATINUM, MERCURY, and ARSENIC, 28.
ILLUSTRATIONS OF MINERAL LODES. pp. 90 to 94.	Wall-cases at north end of Museum, on either side of Model Room, 24 to 36.
COLONIAL MINERALS. pp. 95 to 99.	Wall-cases on E. side, 37 to 42. AUSTRALIA, 37, 38; EAST INDIES, 38 to 40; CANADA, 40 to 42; NOVA--SCOTIA, NEW BRUNSWICK, BRITISH COLUMBIA, and WEST INDIES, 41; SOUTH AFRICA, 42. N.B. Australian Gold in Pedestal Case, No. 19 on W. side.
NON-METALLIC MINERALS. pp. 132 to 146.	Horse-shoe Case in central area.
MODELS OF CRYSTALS.	Case in lower gallery, at entrance to the model rooms. Models on top shelves of wall-cases on principal floor.
METALLURGY. pp. 103 to 115.	COPPER SMELTING. W. side, Table-cases 16 and 20; and Copper Manufacture, Wall-cases, 25, 26, 27, and 28. TIN SMELTING. Table-case 20. ZINc SMELTING. Table-case 24. BRASS, GERMAN SILVER, .ANTIMONY, ARSENIC, CADMIUM, COBALT, and NICKEL. Table-case 24. LEAD SMELTING. Table-case 37. SILVER and MERCURY. Table-case 37. IRON and-STEEL Table-cases 41 and 45. ALUMINIUM, GOLD, PLATINUM,. &c. Table-case 15.
GUN BARREL MANUFACTURE. p. 116.	Table-case, No. 13, on W. of Galatea.
SWORDS AND SWORD BLADE MANUFACTURE pp. 116, 117.	Table-cases Nos. 13 and 48, on each side of Galatea.

Central Cases and Models.

MODEL OF THE PUTS OF AUVERGNE (NO. 11)_i in front of Galatea, opposite entrance p. 115

MODEL OF PART OF ISLE OF WIGHT (49), on E. side of William de Vallence's Tomb p. 132

MODEL OF ISLE OF ARRAN (9), on W. side of do. William de Vallence's Tomb p. 117

West Side, commencing at the S. End.

BLOCK OF EOZOONAL LIMESTONE, CANADA (No. 8) p. 118

ART APPLICATIONS OF METALS (14) p. 118

PRECIOUS METALS, METEORITES, &c. (15) p. 121

MONT CENIS.—CHILIAN GOLD, &c. (17) p. 123

CHINESE BRONZES, &c. (18) p. 119

AUSTRALIAN GOLD, &c. (19) p. 124

MODEL OF THE ALPS (21) p. 125

ELECTRO-METALLURGY (22) p. 120

LEAD AND ZINC ORES (23) p. 125

SPECULAR IRON ORE (25) p. 125

NEWCASTLE COAL PIT (26) p. 125

APPARATUS FOR LOADING COAL (26) p. 126

MODEL OF HOLMBUSH MINE (27) p. 126

LANDSLIP AT AXMOUTH (28) p. 126

PEAT MOSS AT AUCHENGRAY (29) - p. 127

MODEL OF PART OF ALSTON MOOR (30) p. 127

MODEL OF AUSTRALIAN GOLD WORKINGS (31) p. 128

MINERAL LODES OF CORNWALL (32) p. 91

At the End of the Gallery.

MODEL OF A STEEL MANUFACTORY (33) p. 113

PLAN FOR CONDENSING LEAD FUMES (34) p. 128

WATER-BAROMETER p. 128

East Side, commencing at the N. End.

MODEL OF PART OF ISLE OF WIGHT (No. 35) p. 129

PUMPING WHEELS AT DEVON GREAT CONSOLS (36) p. 129

AGATES (38) p. 129

IRON AND STEEL CASTINGS (39) p. 129

MODEL OF SALT MINE AT HALL, TYROL (40) p. 130

SWEDISH IRON (42) . p. 130

CHINESE ENAMELS, &C. (43) p. 131

MODEL OF SALT MINE AT HALLSTATT (44) p. 130

FLINT IMPLEMENTS.—MOSAICS (46) p. 131

MODERN GLASS (47) p. 68

SLAB FROM BONE CAVERN AT LES EYZLES (50) p. 131

N.B. The numbers of the table-cases are in italics, as Cases 1, 2. The wall-cases are indicated by a thick figure, thus, 21..

Ceramic and Vitreous Series

On the Eastern and Western Sides of Stairs.

POTTERY AND PORCELAIN. (Western Side.) Cases 2, 3, 4, 5, 6; and Wall-cases on the W. and E. sides of the embayments. Raw Materials, E. gallery. (The numbers and letters, as R. M. (Raw Materials), M. 1 (Material), Vi. 1 (Vitreous Series), &c., correspond with similar ones on the articles exhibited, and with the catalogue of British Pottery, &c.)

In the flat cases in the lower gallery on the eastern side will be found an interesting collection of the materials employed in the manufacture of pottery and porcelain; and a valuable series of British clays (collected and presented by George Maw, Esq., F.S.A., G. B., and L. S.) is now in course of arrangement in the lower divisions of the pedestal cases occupying the two embayments..

Clay

Clay, the plastic material upon which all ceramic manufacture depends, is essentially a hydrous silicate of alumina, its peculiar fictile properties being due to the presence of the combined water. The proximate constituents of pure clay are here represented by the rock crystal (R. M. 1), a pure form of silica; and by the emery, (R. M. 2), an impure variety of alumina. The silicate of alumina formed by the union of these two compounds—silica and alumina—exists in combination with certain alkaline silicates in all the members of the felspar group; and it is by the decomposition of these felspathic minerals that our china-clays are produced. In the common species of felspar called orthoclase (R. M. 3), a specimen of which is here placed as a representative of the family, the silicate of alumina is associated with a silicate of potash. When the felspar suffers decomposition the greater part of the alkaline silicate is removed in a soluble form, whilst the silicate of alumina, being left behind in a hydrated condition, forms the clay which we employ in our fictile manufactures. Specimens are exhibited of our principal pottery clays, of which the following are the more important :—

Bovey Clay (R. M. 4)

This is obtained from Bovey Heathfleld, Devonshire, and is derived from the decomposition of the felspars of the great granite ranges of Dartmoor. Above 42,000 tons were sent from the port of Teignmouth in 1865. The mode of raising it is extremely simple,—the gravel head is removed, and a large rectangular pit is sunk, which is supported by wood. The workmen cut out the clay in cubical lumps weighing about 30 lbs. each, and fling them from stage to stage by means of a pointed staff; it is then carried to the clay cellars, and when properly dried sent to the potters.

Poole Clay (R. M. 5)

Poole Clay (R. M. 5), so called from being shipped at Poole, occurs in the Lower Bagshot beds of Dorsetshire, and contains numerous vegetable remains, principally parts of palms, maples, and such plants as belong to a sub-tropical climate, like that of Africa along the shores of the Mediterranean Sea. Examples of these plants will be found in the cases at the south end of the upper gallery, Nos. 52 and 56. 75,000 tons of this clay were exported in 1865 from the port of Poole.

China Clay, Kaolin, or Cornish, Clay (R. M. 6 to 16)

About 1755 William Cookworthy, of Plymouth, discovered that the clays of Tregonning hill, in the parish of Breague, near Helstone, Cornwall, were of the same character as specimens of Kaolin which he had seen, brought from Virginia. Associating himself in this discovery with Lord Camelford, Cookworthy worked the China clay on his Lordship's property in St. Stephen's, near St. Austell. He established the porcelain manufactory at Plymouth, which was eventually removed to Bristol, and thus laid the foundation of the great advance in porcelain manufacture in this country.

Kaolin or China clay is prepared chiefly in the neighbourhood of St. Austell, in Cornwall, and at Lee Moor, about five miles from Plympton, in Devonshire. The decomposed granite rock is broken out, and is commonly exposed on an inclined plane to the action of a fall of water, which washes it down to a trench, whence it is conducted to catch pits. The quartz, schorl, mica, and other minerals present are chiefly retained in the first pit, and as the water charged with the clay flows onward it deposits the grosser particles, and eventually the pure and fine clay is deposited in tanks prepared to receive it. These tanks are about 9 or 12 inches deep, and when filled with clay the water is turned in another direction, and the mass allowed to consolidate. The clay is then run into a roofed building, beneath the floor of which hot air circulates freely. Thus the clay is dried perfectly. It is then cut into oblong lumps and having been scraped to remove dust from the outside, it is sent to the potteries. In Devonshire and Cornwall artificial heat is applied, but the clay was formerly dried at the natural temperature.

In 1865, 97,750 tons of China clay were exported from Cornwall and 8,570 tons from Devonshire; the value of the Cornish clay was 89,500l.; that of the Devon clay, 6,800l.

The China clay is now used extensively in our paper manufactories, it is finding a new application in the preparation of the figured papers for walls, and it is used extensively in all our bleaching establishments..

China Stone

(R. M. 17 to 21)

This is the production of the granite rock which furnishes the Kaolin, but in a less advanced state of decomposition—the felspar still retaining much of its silicate of potash or soda, associated with the quartz and scales of a greenish yellow talcose substance. Of China stone there were sent to the potteries from Cornwall in 1865, 25,500 tons, of the value of 20,500l..

Flints

Flints, as obtained from the chalk districts (R.M. 22), and in a prepared state, calcined, crushed, and ground (R.M. 23 to 25). It is said that the introduction of flints into the manufacture of pottery was by Mr. Ashbury, a Staffordshire potter, who was led to make experiments on their use from the following circumstance :

In 1720, riding to London on business, as was then a common practice, he found, on reaching. Dunstable, that his horse's eyes were disordered : he consulted the ostler at the inn, who placed a piece of flint in the fire, heated it to redness, and after throwing it into water, reduced it to powder, a little of which powder he blew into the horse's eyes. Ashbury observing the white character of the burnt flints, sent some to Shelton, -where he had them burnt and powdered, and mixing the powder with pipe-clay, he first washed his ware with it, but ultimately introduced the flints into the body..

Porcelain manufacture

The raw materials in boxes are those employed at the French porcelain manufactory of Sevres; and those in bottles are examples of the materials used in the porcelain works at Berlin.

As space will not allow of a detailed description of the various processes of pottery manufacture, the following outline must suffice. The prepared materials reduced to a finely divided state and suspended in water, are mixed in due proportions; and the fluid mixture, or 'slip,' brought to a pasty consistence by evaporation in the slip kiln.' The paste thus prepared is shaped, either by moulding, or more usually by ' throwing ' on the potter's wheel; and the form, if necessary, is afterwards perfected by turning in the lathe. When handles or other appendages are to be added, they are attached at this stage by means of slip. After slowly drying, the ware is packed in fire-clay boxes, called Beggars, and baked or 'fired' by exposure in the biscuit kiln. The porous baked ware, known in this state as ` biscuit,' is then ornamented by painting or printing; and having been dipped into the glaze suspended in water, is finally baked in the ' gloss kiln,' where by the vitrification of the glaze the pottery becomes covered with a thin coating of transparent and impermeable glass. The various stages in the manufacture are illustrated by specimens in this case.

The arborescent patterns upon (M. 10 and 11) are produced by having, first, an evenly-spread coating of dip over the ware, and then dropping upon it another ' dip ' compound, having a greater density than the first : by holding the piece so that the heavier colour can descend amid the moist, first-spread 'dip,' it disseminates its particles in an arborescent manner.

Several designs will be found in this case illustrating the transfer of engravings to pottery, a process now constantly employed in its ornamentation. Being recently printed on a thin paper, the design is applied to the surface of .the absorptive ware, and being carefully rubbed close, the article is dipped into water, the wetted paper is then removed by rubbing, and the design is fixed on the absorbent clay, which is then glazed and fired in the ordinary way. An earthenware slab (B 328, Wall-case W. side), in the form of a framed picture, shows a transfer in colours of Mulready's "Village Schoolmaster."

It is ever interesting to trace the progress of any special industry bearing upon an important branch of modern manufacture. The Museum of Practical Geology was intended to show how mineral products have been rendered useful; and as our ceramic manufactures form an important feature, some history of their progress was deemed desirable. To read the series aright, it will be necessary to examine this art-manufacture in some of the most ancient of the preserved examples.

We know that bricks were made at a very early period in man's history. Probably as soon as the migratory tribes inhabiting the valleys to the south of the Caucasus,—which appear to have been the abiding places of the shepherd kings,—found fixed homes more convenient than temporary dwellings, sun-dried clay was employed. These rude bricks would soon give place to others more completely indurated by the action of fire. Gradually ornamentation of various kinds would be introduced, and in the examples in Case 5 we have coloured glazes, showing the extent to which a knowledge of the combination of the metallic oxides with silica prevailed at least 800 years before the Christian era.

Assyrian and Babylonian bricks

Case 5. (Vi. 1 to Vi. 6.)

The glazes have been examined in this establishment, and they are found to be silicates of soda, or soda glasS, coloured opaque white with oxide of tin (Putty powder), yellow with antimoniate of lead (Naples yellow), and blue with silicate of copper. The blue colour from copper was previously known, but the use of lead, antimony, and tin,

in glazes or enamels, has to be carried many centuries further back than has been usually supposed.:

Egyptian sepulchral figures, &c.

Case 5. (Vi. 7 to 20.) Many of these figures are of pottery—but some of the figures and scarabni are found to be carved out of a steatitic mineral. These have beers dipped in a cupriferous glaze and then fired, the steatite resisting the heat required to fuze the glaze.

Those examples of the times of the Pharaohs serve to show the early condition of the potter's art : from them we learn that the Egyptians had found that steatitic minerals might be advantageously employed in the place of the ceramic bodies..

Indian enamel

Case 5. (Vi. 20c.)

In this specimen the frits are enamelled with different-coloured glasses and enamel frits, then cut so as to form a design in mosaic, when embedded on a wall of ekanam or plaster. These enamelled frits have been used in India from the 13th century. This example is from the tombs of the Booth dynasty, Golconda..

Ancient Greek pottery

Case 2. (Vi. 21 to 41.)

In the Greek vases may be studied, in addition to the character of the clay bodies, the

Roman Pottery from the Rhine. Case 2

As examples, important for comparison with the pottery found in Roman Britain, these are of much interest. They were manufactured on the banks of the Rhine, where, in several localities, Roman pottery kilns have been found. It is not improbable that the red lustrous ware of Rhenish manufacture was introduced into Britain; it is certain that large ctuantities of pottery- of a precisely similar character have been discovered in this country.

Roman potters' kilns and tools discovered in Britain

Case 2. (A. 68 to 83.)

The kilns of which these are models were found at Normanton Field, Castor, near Peterborough. A great number of such kilns were discovered by Mr. Artis, and the following quotation from his description of them shows the extent to which earthenware manufacture was carried on in this country by the Romans.

"I have now traced these potteries to an extent of upwards of 20 miles. They are principally confined to the gravel beds on the banks of the Nen and its tributary streams; the clay used at some of them appears to have been collected at some little distance from the works. The kilns are all constructed on the same principle. A circular hole was dug, from three to four feet deep and four in diameter, and walled round to the height of two feet. A furnace, one-third of the diameter of the kiln in length, communicated with the side. In the centre of the circle so formed was an oval pedestal the height of the sides, with the end pointing to the furnace mouth; upon this pedestal and side wall the floor of the kiln rests; it is formed of perforated angular bricks meeting at one point in the centre. The furnace is arched with bricks moulded for the purpose. The side of the kiln is constructed with curved bricks set edgeways in a thick slip (or liquid) of the same material to the height of two feet."

In the creeks of the Upchurch marshes may be detected, at a depth of about three feet from the present surface soil, a stratum, often a foot thick, of broken pottery. This deposit of pottery has been traced at intervals through an extent of six or seven miles in length and two or three in breadth. These two places, Castor and Upchurch, were in all probability the great pottery manufactures of the Romans during the period of their colonization. (Wright, The Celt, the Roman, and the Saxon.) The bone and ivory tools, and the bronze instruments—all found at Castor—were used, there can be but little doubt, for producing patterns on the clays. A large fragment of a cake of glass or frit (A 83) was also found in this pottery. This has been analyzed in the establishment, and found to be a silicate of soda and lime, similar indeed to much of the Roman glass..

Roman pottery found in Britain

Wall-case. (A 1 to 186.)

The British-Roman pottery is of three descriptions. The Upchurch pottery, which is of a fine and hard texture, is a blue black, which was produced by baking it in the smoke of vegetable substances. The forms are very varied and the patterns much diversified. Mr. Wright says, "There can indeed be no doubt that the Upchurch marshes furnished a great portion of the commoner pottery used in Roman Britain."

The Castor or Durobrivian pottery was of a superior quality, and adorned with more elegance than that of the Upchurch marshes. Mr. Artis has explained, in his Durobrivce of Antoninus, the mode of manufacture. The third variety is the Samian Ware, go called from being similar to the earthenware made from the red clay of Samos. Of this a very large quantity has been found in England : whether the Samian ware was ever manufactured in Britain has given rise to much discussion. That it must have been of much value is proved by finding bowls and patere of this red ware, which have been broken by their Roman possessors, and subsequently mended by means of lead rivets : (S 15) is an upright vase mended by lead in the same manner as earthenware and china are now mended by metallic wires or bands, and there are some other examples. The common Samian ware of Britain is of delicate texture and of a fine red colour. Many of the specimens exhibited were discovered during the progress of the improvements going forward in London : Cannon Street, Foster Lane, Queen Street, and Lad Lane have yielded a large number of these relics.

Vases, bowls, lamps, unguentaria, amphoræ, terra cotta figures, tiles, hollow flue-bricks, water-pipes, &c., which are exhibited, instruct us in the character of the early pottery manufacture of this country. The historical collection would be necessarily incomplete did it not include illustrations of the pottery of the periods between the 12th and 16th centuries..

Mediæval pottery

Case 5.

Under this general head are grouped many articles dissimilar in character, and widely separated in date. These examples were collected for the purpose of exhibiting the progress of glazing. The tiles (Vi. 42 to 52) which have been found in various parts of England; those (Vi. 53 to 58) of the Moorish palace of the Alhambra and the Alcaza show not only the use of a lead glaze, but also of a stanniferous one. Moorish tiles were probably introduced into Italy in 1115, when Majorca was taken by the Pisans, and they were for a long period employed for ornamental purposes in churches.

Luca della Robbia, celebrated for his terra cotta figures and bas-reliefs covered with a stanniferous glaze, also made enamelled tiles, which he introduced into the church at Pisa about 1415–20.

Majolica or Raffaelle Ware

Case 5, and Wall-case (Vi. 59 to 64.)

The Moorish ware was first introduced into Majorca, and from thence it spread over Italy, under the name derived from this island, "Majolica." It has been called Beadle ware from the fact of some of the designs of that painter having been employed : many of them are by artists of his school, but Ralfaelle, writing to the Duchess of Urbino, informs her that the designs are ready which she had desired for porcelain for her sideboard. This ware was most extensively manufactured from 1540 to 1560. It was especially patronized by the Dukes of Urbino, whose arms are on the rim of one of the specimens (Vi. 60), but Duke Francesco Maria II. being overwhelmed with debt, dismissed his best artists, and consequently the ruin of the manufacture followed. The chief point to be observed in the Majolica is, that the body or paste was first fired, and then by immersion covered by a composition of oxide of lead, oxide of tin, and white earth, the proportion of tin being increased as the enamel was required to be white and hard..

Palissy Ware

Case 5.

Palissy of Salutes was in every respect an extraordinary man. He was born in 1509, at Chapelle Biron, a poor hamlet near the small town of Biron in Perigord, but politically situated in the diocese of Agen. He was educated as a glass painter. He writes of himself in L'Art de Terre, "I for a long time practised glass painting until I was assured that I could earn bread by labour on earth." Some accidental circumstance directed his attention to pottery, and he was seized with an earnest desire to discover an enamel for a clay body which would equal anything which had been produced. Not knowing what had been done by others, he, with the utmost enthusiasm, proceeded in his inquiry. Bernard Palissy, speaking of his experiments, says, "Having blundered several times at great expense, and through much labour, I was every day pounding and grinding new materials and constructing new furnaces, which cost much money, and consumed my wood and my time." Again, he says, "I fooled away several years with sorrow and sighs, lessening the bread of my children, and weighed down by domestic cares." Eventually success crowned his endeavours, and the works of Palissy the Potter became famous. The example given (Vi. 65) shows the character of this ware, in which its author,—a devout lover of nature,—executed in relief, reptiles, fish, plants, and even the fossil shells of the environs of Paris, with the most marked attention to the minutest peculiarities..

Delft Dish

(Vi. 66.) Case 5.

The manufacture of the famous Delft ware was established about the commencement of the seventeenth century, and for a long period was much esteemed in this country. The composition of four of the most important of the wares named proves very similar. Brongniart gives the result of his analyses as follows :—

	Silica	Alumina	Lime	Manganese	Iron	Carbonic Acid &c.
Luca della Robbia	49.65	15.50	22.40	0.17	3.70	8.58
Majolica	48.00	17.50	20.12	1.17	3.75	9.46
Delft	49.07	16.19	18.01	0.82	2.82	13.09
Palissy	67.50	28.51	1.52	—	2.05	—

The marked difference between the Palissy and the other wares is the increased quantity of silica, and the exceedingly small proportion of lime..

Chinese Porcelain

Case 5. (Vi. 67 to 75.)

These illustrations serve to show us in what respects we have still to learn something of these celebrated oriental potters. Many of the peculiarities presented in their works have not yet been successfully imitated in Europe; the colours given to the jar (Vi. 72) furnish one example of this—here a felspar glaze is employed, and the blue silicate of copper has been partially reduced to the red sub-oxide: thus a portion remains of a purple colour, from the dissemination of the sub-oxide amid the silicate of copper. Cracklin China (Vi. 74, 75, a and b) is produced by covering the white porcelain body partly with a brown felspathic enamel, and partly with a thick opaque enamel which, after firing, "crazes" or splits in various directions,

The Chinese porcelain is stated to be made at several places in the empire. Davis informs us that there is a large manufactory at King-te-chin, and another at Chaou-king-foo, west of Canton; it is said that at the former place there are nearly 3,000 kilns.

The Chinese potters employ Kaolin (from Kaou-Ling—lafty ridge) and pe-tun-tse. The Kaolin is similar to the Cornish China clay, and the pe-tun-tse, in all probability, is like the China stone of the same district. Huct-she (slippery stone), steatite, or soap stone is also used by the Chinese. Laurent and Malaguti give analyses of the Chinese ware :—

	Silica	Alumina	Potash	Lime	Protroxide of Iron	Magnesia
Body of a white vase	70.5	20.7	6.0	0.5	0.8	0.01
Body of a greenish white plate	53.5	28.5	5.0	0.6	0.8	Trace

The earliest mention of China ware in England is in 1586..

Meissen Porcelain

Böttcher Ware. Wall-Case.

Bottcher, in the commencement of the 18th century, made the earliest specimens of true porcelain in Europe. He first worked at Dresden with a brown clay, found near Meissen, and produced a red ware; and in 1709 he made white porcelain. Augustus II., Elector of Saxony and King of Poland, established porcelain works at Meissen, and Bottcher was appointed director in 1710. In 1715 he succeeded in making fine and excellent porcelain. This manufactory has continued to the present day, producing that superior porcelain commonly known as Dresden China. There is a curious story connected with this manufacture. John Schnorr, an iron-master, riding near Aue, observed that a soft white earth adhered to his horse's feet; considering that this earth might be used as a substitute for wheat-Hour as hair powder, he carried some away with him, and it was subsequently sold in large quantities for this purpose at Dresden, being known as Schnorrische weisse Erde (Schnorr's white earth). Bottcher finding his hair powder was heavier than usual, was induced to examine it, and this led to the discovery of the use of kaolin in porcelain at Meissen, where its employment was long kept a profound secret. The establishment at the Albrechtsburg was a complete fortress for the confinemeut of the people employed, and "Be secret until death" was placed on the walls of the workshops. The specimen of Bottcher ware exhibited was produced in 1796.

From Meissen, however, the secret of the manufacture of porcelain spread, and Berlin, Munich, and St. Petersburg, about the middle of the 18th century, boasted of their potteries, The Sevres works were established at St. Cloud before 1695, but it was not until about 1769 that the use of kaolin was introduced, it having been then recently discovered at St. Yrieix, near Limoges.

We may now, having marked the principal points in the progress of this manufacture, pass to the English pottery, of which the Museum can boast a highly illustrative series..

Staffordshire Pottery and Porcelain

Wall-cases. West Side.

"The Potteries" have been celebrated in this country as a locality in which, from a very early period, earthenware was manufactured. We are not enabled to connect the early Staffordshire ware with the British-Roman by any existing links; the earliest manufacture of which we have any exact account being that of a coarse ware in 1500. The button pot (B 1, 2, 3) was such an important branch of the Staffordshire manufacture in 1670 as to be the subject of an Act of Parliament. Plott, who wrote in 1686, says, "The butter they buy by the pot, of a long cylindrical shape, made at Burslem, in this county, of a certain size, so as not to weigh above six pounds at most, and yet to contain at least 14 pounds of butter, according to an Act of Parliament made about 14 or 16 years ago for regulating the abuses of this trade." Dr. Shaw remarks in 1829, "that the common people of the district, at the present day, call Irish tub butter pot-butter." Pot-butter is still a common term in the western counties, and frugal housewives talk of "potting" butter for the winter supply in the spring and early summer. The drinking vessel in the form of a bear (B 4) is so formed that it could not be set down until it is emptied, hence the adage "'ware the bear." The tygs (B 5 to 16) were the many-handled drinking cups of those times; each person drinking used a separate handle, and hence brought their mouths to different parts of the rim. The candlestick (B 17) has a date upon it, 1649, and the large dish (B 20), ornamented in the centre with a crowned lion, bears the maker's name, THOMAS TOFT. These and sundry mugs, porringers, &c. (B 29 to B 44), mark the peculiarities of the manufacture of Staffordshire before 1680, up to which time the clays employed appear to have been all obtained from the coal-measures of the neighbourhood.

In 1690 the Elers brothers came from Nuremberg, and at their works, which they established near Burslem, they made the red ware exhibited (B 45, 56), in imitation of the Japanese pottery. Many strange and some improbable stories are related of these potters and their jealous rivals; but certain it is that the Elers, from competition and annoyances, were compelled to abandon their works in Staffordshire somewhere about 1710. Better clays were introduced, and the use of flint in pottery was discovered; thus the cream coloured ware and the white ware were gradually manufactured. It will be observed that the forms are more perfect than they were; this may be referred to the introduction of plaster of Paris moulds, which were adopted from the porcelain manufactories of France. The ornamentation is altogether of an improved description, and it is evident that great attention was now paid to this increasing branch of trade.

Early examples of the transfer of engraving upon the glaze will be found.

The busts of Shakespeare in colours and in black Egyptian ware, and the bust of the Madonna in colours, mark the advances of our earthenware in another new direction.

Wedgwood's Ware.—This collection exhibits the remarkable improvements which were at once made by a man who united great energy of character with a fine appreciation of the beautiful. Wedgwood was born in 1730, and as a boy worked in a small pottery belonging to his father, as a thrower. In 1759 he commenced for himself in an humble way, manufacturing small ornamental articles. He very much improved the Cream, Ware of the time, first made by Mr. Wood, and having introduced it to Queen Charlotte, he received permission to call his manufacture Queen's Ware. This ware and his knife-handles must be regarded as the foundation of Wedgwood's fame and fortune. Associated in partnership with Mr. Bentley of London, Wedgwood succeeded in securing the assistance of artists, such as Flaxman, and the support of the patrons of art. From this time may be dated those beautiful productions which are so associated with the name of Wedgwood—vases, cameos, medallions, and the like, which have not been excelled by any manufacturer since his time.

As a fine example of Wedgwood's productions, a copy of a large Greek vase (B 193, one corner of the opening from the Hall) in the British Museum collection should be examined. This, the largest work executed by Wedgwood, was presented to the Museum by the late Mr. Apsley Pellatt; the original was formerly in Sir W. Hamilton's collection. It belongs to the latest period of vase painting, known as the

Another example of a modern copy of an antique vase is placed opposite to the Wedgwood vase; this is, however, from the manufactory at Naples.

L. Arnoux, in his Lecture on Ceramic Manufactures, says :—"It is not only that Nature, when she gave the English people commercial and industrial genius, gave them also a soil richly supplied with the best materials for this manufacture, but it is to the exertions of some men of genius that England is indebted for this result; and I think it only just to consider Wedgwood as the man who has given to the English ceramic art the powerful impulse it has preserved up to the present time."

Spode's Ware (B 195 to 208).—This may be regarded as the connecting series between the productions of Wedgwood, those of Copeland and Garrett, and those of Mr. Minton, which mark in a satisfactory manner the present condition of our Ceramic manufactures. Before quitting this side of the Museum the modern Staffordshire productions should be carefully examined,—although the productions on the eastern side are generally of earlier date..

Modern Staffordshire

(B 211 to 239).

The present productions of the Staffordshire potteries are evidences of the successful attempts which are now making to equal the best examples of any country.

Modern English earthenware, which has of late years greatly improved, requires no description in these pages.

The English porcelain is what is called soft porcelain, and is composed of three constituents, Kaolin and Cornish China stone, with bone ashes.

Soft porcelain differs from hard by the presence of phosphate of lime, and by containing a small quantity of alumina and a large proportion of vitrified materials. The soft porcelain cannot resist the sudden changes of temperature; and generally, when you see a very transparent pottery, you may be certain it will not stand the fire; there is only one material which gives that property—it is the alumina, and that is perfectly opaque. (Amour.) Soft porcelain requires two firings, one for the biscuit, and the second for the glaze; the last, however, at a much lower heat.

There are 185 factories existing in this country for making pottery; of these not more than 24 are engaged in the manufacture of the soft porcelain.

Case 4 contains examples of the first class of our Ceramic manufactures at the time of the Great Exhibition of 1851..

Parian, Carrara, Statuary Porcelain

Case 4.

By these names a vitrified body which is intended to imitate statuary marble is distinguished. It has not been introduced many years, and the result obtained depends on the employment of a soft felspar, instead of the Cornish stone. The fabrication of Parian figures requires more dexterity than any other branch of porcelain manufacture. The proper mixture of prepared clay and felspar being made, it is mixed to the consistence of cream, technically called "slip," and in this state poured into moulds of plaster of Paris, which absorb the water from the clay. These figures are cast in a great number of separate pieces; as many as 50 moulds are required for some pieces, and much experience and a knowledge of the human figure are required to unite them into one. The figure being formed from the cast pieces still requires much attention. In the processes of drying and firing the model shrinks no less than one quarter, and as the contraction is in all directions, and is determined by the thickness of the body, various allowances have to be made. Again, being made of a fusible material, these would lose their shape, and fall, if not supported all round with props of the same material. The firing itself requires great attention, as on it depends the colour of the figure—the colour being due to a silicate of the peroxide of iron, which produces the yellowish white which is so agreeable in these figures.

The specimens exhibited will sufficiently show the applicability of this material to the reproduction of the finest works of art. Its capabilities are great—but as yet, owing to the difficulties of manufacture, it has not been possible to render those porcelain figures so cheaply as could be desired. In the education of the people, the advantages to be derived from rendering them familiar with the most beautiful objects are so evident, that no effort should be spared to improve this manufacture, and to place the results within the reach of every one..

Terra Cotta

(Galatea, No. 12, opposite the Stairs.) Case 4. Figures in the lower Hall, Nos. 17, 22, 25, and 138.

This term signifies literally baked earth, and it may therefore be extended to numerous articles of pottery.

The revival of the manufacture of terra cotta in England belongs to Josiah Wedgwood, who in 1770 manufactured it largely in Staffordshire. In 1790 a manufacture of terra cotta was carried on in Lambeth by a lady of the name of Coade, and until within the last few years by Coade and Sealey, who made large articles, such as statues, vases, &c., and architectural decorations, in the production of which such artists as Bacon, Rossi, and Parrietta were engaged. Rossi manufactured the capitals and statues of St. Pancras Church of this material; and the frieze of the Opera House in the Haymarket is from the manufactory of Mr. Bubb.

In executing a work in terra cotta the original work is first modelled in clay, and a plaster of Paris mould is then taken from this. Sheets of clay are beaten on a bench to the consistency of painter's putty, and pressed by the hands into these moulds. After the clay has been allowed to dry a little in the plaster mould, the latter is removed and the clay moulded article is exhibited. A skilful workman or artist goes over this, and removes the seams left by the mould where the sections come together, and repairs any defects which appear on the surface of the impression. The work is then left to dry gradually, and if large, props are properly applied; when sufficiently dry for baking, it is conveyed to a kiln, and the fire being gradually raised, it is baked, and the article becomes Terra cotta. The heat should be of sufficient intensity to blend and partly vitrify the materials of which the mass is composed, without melting or distorting the ware. As soon as this temperature is obtained the firing is stopped, and all apertures closed to prevent the admission of air. When the kiln has cooled, the finished terra cottas are withdrawn. The example of Galatea will convey an idea of the size to which such works can be carried. The figure of Australia, modelled by John Bell, and manufactured by Mr. Blash-field, which is at the Crystal Palace, Sydenham, is of the height of nine feet—this was burnt in one piece. Several other figures equally colossal have been manufactured at the Millwall terra cotta works, and at the establishment of Mr. Minton, Stoke-upon-Trent. (See History and Manufacture of Ancient and Modern Terra Cotta, by J. M. Blashfield.)

Friezes, Enamelled Bricks, Tiles, &C.

Specimens under Window, and in Wall-cases, Western Side.

The friezes, of which there are four, are in imitation of the Luca della Robbia ware; the other examples of ornamental earthenware are intended to show its applicability to the decoration of rooms and other architectural purposes.

The hollow bricks are thought to combine the advantages of strength and lightness, and, from the free circulation of air through the perforations, to ensure perfect dryness to the walls. These are manufactured by Prosser's process (p. 37); they are then painted and enamelled, so that the interior decoration of an edifice is produced as the wall is built.

On the bottom shelves of the wall-cases on this side are several examples of enamelled tiles, and in connexion with these may be noticed a view of Redcliffe Church, Bristol, in old Dutch tiles, which will be found on the wall near the window on the opposite or eastern side..

Painting Pottery

Table-cases 3 and 6. Sundry examples in the Collection.

The colouring materials employed in painting pottery always consist of a mineral colouring agent, usually a metallic oxide, associated with some easily fusible substance, such as an alkaline silicate. On exposure to heat this flux fuses to a vitreous mass, which becomes coloured by the metallic oxide, and hence all pottery-pigments may be simply regarded as coloured glasses. Those colours which are neither volatilized nor decomposed by heat are applied to the ware when in the state of "biscuit," whilst the less stable colours which would be injured during baking are not applied until after glazing, the colour being fused by subsequent exposure to a comparatively gentle heat in a muffle.

A most interesting series of porcelain colours from the works of Sevres and Berlin is arranged in Table-case 3; and immediately facing this, in No. 6, will be found a highly illustrative series of British pottery colours, prepared and presented by Messrs. Emery, of Cobridge.

The process of transfer-printing on pottery has been explained at p. 50. The blue colour so general on common earthenware is produced by the oxide of cobalt.

In Case 3 are placed some specimens of modern French porcelain interesting for the peculiar mother-o'-pearl lustre of its enamel.

(The collection on the eastern side should now be brought under notice.)

Pottery on eastern side

Wall-cases..

Bow Porcelain

The Bow porcelain works existed for some years prior to 1767, when they appear to have been discontinued.

A writing on the cover of a box in the British Museum, containing a porcelain bowl, informs us that "the above manufactory was carried on many years under the firm of Messrs. Crowther and Weatherby, whose names were known almost over the world; they employed about 300 persons; about 90 painters (of whom I was one), and about 200 throwers, turners, &c., were employed under one roof." The writer, who was the enameller of the bowl, signs his name, T. Craft, 1790..

Chelsea Porcelain

Under the auspices of the Duke of Buckingham, in 1676, some Venetians established at Chelsea a glass-manufactory. As the Venetians well understood the manufacture of opaque glass (see the Venetian Case), the transition from this manufacture to that of porcelain was easy. It is said that the Elers (Elers ware on W. side), when they left Staffordshire in 1720, joined these works, and greatly improved the ware and the designs. The Chelsea potters are stated to have obtained Kaolin from China, but this is doubtful, as they obtained sand from the Isle of Wight; and they probably procured from Dorsetshire the clays then well known. George II. especially encouraged the Chelsea works, procuring models, workmen, and materials from Saxony and Brunswick for them. The greatest excellence was achieved, and the works were in the height of success between 1750 and 1765. A set of Chelsea porcelain is stated by Horace Walpole to have been presented by the King and Queen to the Duke of Mecklenburgh, which cost 1,2001. (Marryat's History of Pottery and Porcelain.)

These works were discontinued about 1765, and the models were purchased for a manufactory at Derby..

Derby Porcelain

These porcelain works were founded by Mr. William Duesbury in 175L Not only did the Chelsea moulds find their way to Derby at the closing of those works, but the workmen and artists also. Derby may be regarded as having united in another locality the porcelain works of Bow and Chelsea. Boswell, recording Dr. Johnson's visit to the Derby works, says that the great doctor admired the beauty of the porcelain, but objected to the price, observing "that he could have vessels of silver of the same size as cheap as what here were:made of porcelain." The Derby porcelain works continued until 1848, when they were finally closed, a minor manufactory, however, still remaining..

Plymouth Porcelain

The works at Plymouth were established by Mr. William Cookworthy, who has been already mentioned in the notice of Kaolin (p. 49). Lord Camelford united with Cook-worthy in obtaining a patent, and establishing the works. His Lordship in a letter to Mr. Polwhele says :—" The difficulties found in proportioning properly those materials, so as to give exactly the necessary degree of vitrification, and no more, and other niceties with regard to manipulation, discouraged us from proceeding with this concern, after we had procured a patent for the use of our materials, and expended on it between two and three thousand pounds. We then sold our interest to Mr. Champion, of Bristol." —(See Prideaux's Relics of Cookworthy.)

Bristol Porcelain and Earthenware

Mr. R. Champion transferred the Plymouth works to Bristol. In 1772 works were established in the Castle Green, Bristol; and in 1787 the present earthenware pottery was established at the Temple Backs..

Leeds Ware, 1760

The Leeds pottery in 1786 was in a flourishing condition, Mr. Green, the then proprietor, publishing a book of patterns, of which a copy is in the library of this institution, with the title of "Designs of swndry articles of Queen's or cream-coloured earthenware, manufactured by Hartley, Greens, and Co., at Leeds pottery. The same enamelled, printed, or ornamented with old to any pattern; also with coats of arms, cyphers, landscapes, &c., Leeds, 1786." The potters' field is still known by that name in Leeds, and the bone-mill has only disappeared within a few years..

Rockingham Porcelain and Earthenware

ThiS pottery was manufactured at Swinton, near Rotherham, Yorkshire. It takes its name from the Marquis of Rockingham, upon whose estate the works were established in 1757. A portion of these works is still occupied..

Worcester Porcelain

The Worcester works were established in 1751, through the exertions of Dr. Wall, a physician of that city. The early productions of Worcester were mostly imitations of China and Japan wares. It is, however, highly esteemed for its good qualities, and this was probably due to the employment of the Cornish Kaolin in the ware. It seems probable that Mr. Cook-worthy, after he left the Bristol works, was engaged in those of Worcester. In 1783 the Worcester porcelain works were purchased by Mr. Thomas Flight, from whom they afterwards passed to Messrs. Flight and Barr..

Shropshire, Colebrook Dale, Swansea, Nantgarw, Nottingham, Liverpool, and Yarmouth Porcelain.

Of these works a brief notice must suffice.

Shropshire works were established about 1772

Colebrook Dale works were established about 1780

Swansea works were established about 1750

Nantgarw works were originated by two men who left the Worcester pottery, and employed the secrets of which they became possessed in those works to their own advantage. Messrs. Flight and Barr checked the proceeding, but this led to the establishment of the Swansea works. The Swansea porcelain is remarkable for the correctness of the natural history subjects with which they are embellished, Mr. Lewis Weston Dillwyn, the proprietor of the works, being much devoted to the study of this science. In 1817 the porcelain manufactory was abandoned, earthenware alone being from that time produced in Swansea. Nottingham ware does not appear to have been made extensively at any time. In 1641 we learn one potter was in Nottingham, and in 1739 there were two; and potter's ware is said to have been sent down the Trent in 1751. No manufactory now exists, but some old places in the town derive their names from the old works.

According to Mr. Mayer, the first notice of Liverpool pottery occurs in the year 1674. During the last century several manufactories were in existence, the principal being those of Alderman Shaw, Messrs. Sadler and Green, Chaffers, and Pennington. Some large delft punchbowls of Liverpool ware are exhibited, and also some specimens from the Herculaneum pottery, on the opposite side of the Mersey, established in 1794 and abandoned in 1841. (Marryat.)

In the gallery a series of illustrations of ancient and modern specimens of Foreign Pottery and Porcelain is in course of arrangement.

Among the specimens will be found examples of ancient pottery from Mexico, Peru, New Granada, India, Barbary, Etruria, and Rome; and of modern Mexican, Indian, Egyptian, Zulu, Italian, Portuguese, and Spanish pottery. Of Chinese porcelain some specimens will be found with the enamels, &c., in Case 43,

Glass

Cases 47, 52, 53, 54, and 55 on the Eastern Side.

The manufacture of glass, from its intimate relation to certain branches of ceramic art, receives appropriate illustration in this section of the Museum.

Glass consists of a fused mixture of various acid silicates, usually transparent and insoluble, and always destitute of crystalline structure. In a free state silica or silicic acid is highly refractory, but when associated with certain metallic oxides, the resulting compounds are often eminently fusible. The degree of fusibility enjoyed by these artificial silicates is dependent partly on the nature of the base and partly on its proportion, those silicates which contain an excess of base being most fusible, and therefore most easily worked. In practice, however, glass always contains a large preponderance of silica, since it happens that the basic silicates, especially those of the alkalies, are frequently soluble, and hence to a great extent useless for those purposes to which glass is ordinarily applied. As an example of a soluble alkaline silicate, we may refer to the "water-glass" already mentioned at p. 36.

Excluding those oxides which are introduced simply as colouring or decolouring agents, the bases practically employed in glass making are potash, soda, lime, and oxide of lead, but for these bases other oxides may be substituted, as in the zinc- and magnesia-glasses exhibited in Case 52; whilst, on the other hand, the silica may be replaced by boracic acid, as in Faraday's "heavy glass," a silico-borate of lead, of which a specimen will be found in the same case..

Devitrified Glass

Cases 54 and 52.

One of the most essential properties of glass is its amorphous or non-crystalline character. Its component silicates, as definite chemical compounds, possess a certain tendency to crystallize, but the rapid cooling of the fused mass effectually prevents crystallization. If, however, the glass be maintained long in a heated condition, its individual silicates have opportunity to crystallize, and the glass then, losing its vitreous characters, becomes devitrified. From their complex composition bottle and crown glass are most susceptible of suffering this molecular change, and several specimens of bottle "metal" are exhibited in which certain silicates having separated, appear as crystalline products embedded in a vitreous matrix. Under other conditions the entire mass of glass may be devitrified, as in "Reaumur's porcelain," of which samples are exhibited. This peculiar substance is prepared by subjecting glass for a considerable time to a temperature somewhat below its melting point, the result being an opaque white fibrous product, exceedingly hard and tough, and capable both of withstanding sudden alternations of temperature and of resisting the action of chemical agents..

Flint Glass

Case 54.

This is composed of a mixture of silica, alkali, and oxide of lead. Specimens of the raw materials will be found in the upper part of Case 54. Formerly the silica was introduced in the shape of calcined flints, whence the name "flint" glass, but at the present day sand alone is employed. The chief localities in England for glass-making sand are Alum Bay, Lynn, Aylesbury, Wareham, Reigate, and the New Forest; but it is not always of sufficient purity for flint-glass manufacture. Large quantities are also derived from Fontainebleau, in France, and from America, Australia, and New Zealand. The sand is prepared for use by simple washing and calcining, or if necessary by treatment with hydrochloric acid. The alkali in flint glass is usually employed in the form of pearlash, an impure carbonate of potash, the acid being expelled during fusion. The high lustre, great density, and easy fusibility of flint glass are due to the presence of oxide of lead, which is largely introduced into its composition, chiefly as red lead.

To remove the colour imparted to the glass by impurities in the raw materials, especially iron and carbon, certain oxidizing agents are always mixed with the raw materials. Of these oxygen-yielding substances the most common are nitre or saltpetre, arsenious acid or white arsenic, and pyrolusite or peroxide of manganese (p. 78).

The following recipe for the composition of fine flint glass was given by the late Mr. Apsley Pellatt

Carbonate of potash	1 cwt.
Red lead or litharge	2 cwt.
Sand washed and burnt	3 cwt.
Saltpetre	14 lbs. to 28 lbs.
Oxide of manganese	4 oz. to 12 oz.

The ingredients reduced to powder, and mixed with a due proportion of "cullet," or broken waste glass, are fused together in fire-clay melting pots, covered with a hood or dome, to prevent the flames from affecting the "batch," or mixture. One of these crucibles is placed in the western gallery, and the mode of arranging the pots is shown in the model of a flint-glass furnace which is placed at the corner of the lower eastern gallery. These pots are filled but once a week in a flint-glass house, usually on Friday or Saturday morning.

The various charges are melted down and fresh matter supplied, until in about 12 or 15 hours the pot is full of melted metal. Air bubbles and stria) then abound, and they are not expelled until 30 or 40 hours have elapsed; during that period the glass becomes homogeneous. Saturday and Sunday are the days when the furnace requires the greatest heat, so that the working may be commenced on Monday morning. When the melting and refining are completed, the temperature is lowered until the metal becomes sufficiently viscid and plastic to admit of free working.

The details of manipulation are illustrated by a series exhibiting the successive stages in the manufacture of a wine-glass; and several of the simple tools of the glass-worker are exhibited, viz., the pucellas, the spring tool, and the wood tool. The mode of blowing glass in metallic moulds is also illustrated.

The finished article passes from the hands of the glass-blower at a high temperature, and is immediately transferred to the "lear," or annealing oven, to prevent the excessive brittleness resulting from sudden cooling. It has been already stated that the particles of melted glass possess a certain tendency to crystallize, but that this tendency is resisted by the rapidity of cooling. The conditions, therefore, being unfavourable for crystallization, the particles are forced to assume a constrained position, which is necessarily greatest at the surface, where the cooling has been most rapid; and hence the superficial layers are in a state of tension in relation to those beneath, the slightest force being sufficient to disturb the unstable equilibrium and produce disruption. The curious "Bologna phials" placed in this case are samples of unannealed glass, and the well-known "Rupert's drops" are similar examples. The object, therefore, of annealing is to cool the glass with sufficient slowness to prevent the inconvenient brittleness of unannealed glass, but at the same time to avoid such tardy cooling as would induce devitrification.

The final operations of grinding, polishing, and engraving are illustrated by specimens; and a collection of modern objects in flint glass will be found in Case 47, described at p. 68..

Among other specimens in the case before us attention may be directed to an example of cameo incrustation of much interest. The figure, usually made of porcelain clay and sand which has been previously fused with carbonate of potash, is formed in a plaster of Paris mould, and slightly baked. It is then heated to redness, and being placed within a cylindrical flint-glass pocket, the open end is heated and welded together by pressure, so that the figure is in the middle of a hollow hot mass of glass. The whole is re-warmed and the workman exhausts the air by his mouth from within, by means of the tube to which it is attached, and thus by atmospheric pressure the whole becomes an homogeneous body. (See also Case 47.)

An incrusted inscription is another example of a similar character, the letters are drawn upon a piece of glass with a vitrified black paint, and burnt in; the inscribed glass is introduced at nearly a red heat into a glass pocket and treated as already described. Bricks of glass containing inscriptions are now inserted in the foundation stones of buildings, to tell the tale of the founders, and of the state of this manufacture, ages after the bodies of those who fabricated either are resolved again into their primary elements..

Bottle Glass

Case 54.

The various stages in the process of forming a wine bottle are here shown. The raw materials employed in the manufacture of common bottle-metal are of the coarsest description, consisting usually of rough sand, soapers' waste (the alkali employed), gas limes, common clay, and rock salt; but the composition is by no means uniform in different works..

Plate Glass

Cases 52 and 54.

All the cases in the building may be regarded. as examples of plate glass; and the glass in the roof shows the character of the roughened plate. Some examples in these cases furnish instances of peculiarities.

The composition of plate glass varies considerably : sand, salts of soda, or of potash, lime, and "cullet" or broken glass in different proportions are introduced. Peroxide of manganese, arsenic, and saltpetre are employed as decolorizing agents; and often oxide of lead, to impart a brilliancy to the glass. The manganese and the other substances are used to secure the oxidation of the iron, or carbon, which may exist even in the purest materials. An excess of manganese produces a violet colour; and even when at first there is no appearance of colour in the glass, it will upon exposure to sunshine be gradually developed. Instances of this pink or violet tint are exhibited in the cases before us, and the same thing is strikingly shown by much of the plate glass in the roof of the building.

Plate glass is cast upon flat metallic tables, or casting plates, which are warmed previously to the flowing of the glass from the cuvette or crucible to prevent its cooling too rapidly: when properly spread, which occupies but a short time, five minutes only being required, it is passed into the annealing oven, where the plate remains from 8 to 14 days.

The annealing process being completed, the plate is subjected to the operation of polishing, which is effected by means of colcoth,ar (oxide of iron, or crocus), rubbed over the plates with a heavy muller or weighted board.

The various stages in grinding and polishing the plate are illustrated by a series of specimens..

Crown and Sheet Glass

Western Gallery.

In the gallery above the Staffordshire pottery on the western side will be found a series showing every stage of the process of manufacturing sheet and crown glass, with examples of the tools employed.

Crown glass is composed of a mixture of sand, soda-ash, and lime, which after partial fusion in a "flitting oven" is mixed with a proper proportion of cullet, or broken refuse glass, and the whole melted in a glass pot. When thoroughly fused the workman gathers upon the end of a long iron blowpipe a sufficient quantity of the melted glass; and having flattened the mass by rolling upon a "marver," or iron table, blows a pear-shaped flask, which is enlarged by repeated reheating and subSequent blowing. When sufficiently enlarged, the glass globe is transferred to the "pontil" or punt, and the blowpipe having been removed, the "flasher" rapidly rotates the heated globe, which, expanding by the centrifugal force developed by rotation, is finally converted into a flat circular disc; and this, after removal from the punt, is conveyed to the annealing oven : the point at which the punt adhered being thicker' than the surrounding portion, forms the mark called the "bull's eye."

The manufacture of sheet or spread window glass differs somewhat from that of crown glass. Instead of being blown into the shape of a globular flask, the ball of melted glass is extended into a conical form by a swinging motion, and then elongated into a cylinder, which is cut open by means of a drop of cold water falling along a line which has been previously heated by the application of a red hot iron; the cylinder is then flattened upon what is called the spreading plate, or the flatting stone, and the sheet of glass so formed subsequently annealed.

In the Historical Series the following will be found to be of especial interest. The importance of a collection of ancient glass, accompanied by analyses thereof, in connexion with modern illustrations of the use of sands and alkalies, must be evident to every one..

Ancient Glass

Case 53.

The tradition of the discovery of glass by the accidental fusion of sand on the bank of the river Belus can scarcely be received; evidence appears to throw the discovery very ranch further back in time. It is clear that in the age of Moses and Job the art of making glass was known, and it is evident, from the examples preserved in the Egyptian tombs, that the people of those days were familiar with the processes of pressing and moulding glass (see examples). Babylonia, Assyria, and Chaldea have each afforded specimens, which prove not merely that the fusion of silica with an alkali could be effected—this was shown by the enamelled bricks--but that this fused mass could be variously coloured, and worked into articles of ornament. The researches of Layard, Rawlinson, and Loftus have brought us the beads and other ornaments worn by the ladies of the days of Assyrian splendour, found in the great room of the palace of Nimroud; while amidst the relici of brick-built Babylon similar illustrations of the fictile art have been found (see examples).

The specimens of Greek glass of the same general character have considerable interest, as showing the progress of this manufacture; and we must associate in our consideration those illustrations of glass which are regarded as Roman, having been found at Nismes, and Trews, and in London, associated with other relics, marking the spots which Rome included within the bounds of her empire.

It will be observed that these glasses are variously coloured, that some show the process of moulding, others are blown, and some have been cast or else flattened. The Pompeian and Roman architects are known to have used glass in their mosaic decorations; and glass is said to have been employed for admitting light to the houses in Pompeii. Some of these examples of glass have been analysed in the laboratories of the establishment; the following are the results:—

	Silica	Alumina	Protoxide of Iron	Protoxide of Manganese	Lime	Magnesia	Soda
Vase glass	70.58	1.80	0.53	0.48	8.00	trace	18.86
Flatted glass	71.95	trace	3.45	0.57	7.33	0.60	15.30
Lachrymatory	71.45	2.15	1.02	0.17	8.14	trace	16.62

The cinerary urns of green glass will be inspected with much interest; of these Mr. Apsley Pellatt writes, "The round vases are of elegant forms, with covers and two double handles, the formation of which must convince any one capable of appreciating the difficulties which even the modern glass maker would have to surmount in executing similar handles, that the ancients wore well acquainted with the art of making round glass vessels." One of the bottles found at Nismes has been formed by being blown in a mould. The lachrymatories have been. so called from the romantic notion that those bottles were filled with the tears of the mourners for the dead, as they have been usually found in tombs; the received opinion among the antiquaries of the. present day is, that they contained the unguents and aromatics which it was usual to deposit with the dead, The Roman glass beads, from the number of them which have been discovered in various parts, must haves been much in use. It is curious and interesting to.find rock crystal and agate beads associated with glass; this indicating the value which must have been set upon the white transparent glass of those days.

In this case will be found a Druidic bead. These beads were called Glain Neidyr, from glain pure and holy, and neidyr. snake. Mr. Wright appears to think beads of this character are Roman. It is, however, curious to find these beads in the ancient British tombs, in the graves of our Roman conquerors, in the tumuli of the Anglo-Saxons, and at the present day in the Ashantee diatrict of Africa; while a bead in all respects similar is made in Venice.

The Aggry beads, like the others, may be referred to Roman origin; since ft is difficult to suppose that in manufactories so far apart the same general character would have been preserved.

Another set of beads found in Britain are shown; these consist of glass and rock-crystal, and were found with iron weapons in a` stone-sided grave within a tumulus, near the Tynwald Hill, Isle of Man..

Venetian Glass

Case 55.

Venice for a long period during the middle ages was celebrated throughout Europe for its glass. Familiar with the manufacture from an early date, the Venetians, on the capture of Constantinople in 1204, profited by their intercourse with the East, and glass factories soon became so numerous at Venice, that towards the latter part of the thirteenth century they were removed to the adjacent island of Murano. During, the fourteenth century the art was principally directed to the production of beads and other trifles, but a fresh impulse was given to the manufacture on the fall of the Eastern empire; and during the fifteenth and sixteenth centuries Venice produced those peculiar examples of glasswork, which, from their ingenuity of design and delicacy of execution, acquired a wide reputation, and for a long time, defying imitation, enabled Venice to maintain a monopoly of the manufacture. The case before us contains a fine collection of these skilful productions, of which the principal varieties may be briefly described.

Vetro di trina is fine lacework, with intersecting lines of white' enamel or transparent glass, forming a series- of-diamond-shaped sections; the centre of each having an air bubble of uniform -size; this glass was executed almost with the precision of engine lathe turning. The large cup and cover is a fine example of this variety, and there are some other smaller specimens.

Frosted Glass.—The art of making this glass appears to have been lost until it was revived in the Falcon Glass Works about 1850: Mr. Apsley Pellatt thus describes his process 1 "It has irregularly veined marble-like projecting dislocations with intervening fissures. Suddenly plunging hot glass into cold water produces crystalline convex fractures, with a polished exterior like Derbyshire spar, but the concave intervening fissures are caused, first by chilling and then reheating at the furnace, and simultaneously' expanding the reheated ball of glass by blowing, thus separating the crystals from each other, and leaving open fissures between, which is done preparatory to forming vases or ornaments. Although frosted glass appears covered with fractures, it is perfectly sonorous." Filigree Glass.—Filigree canes of plain, coloured, or opaque white are arranged in a mould, a solid ball of flint glass is then heated so that the canes of glass adhere to it, these are marvered or rubbed into an uniform mass, it is then covered with a gathering of white glass, and is formed into any shape.

"The Venetian Ball is a collection of waste pieces of filigree glass conglomerated together without regular design; this is packed into a pocket of transparent glass, which is' adhesively collapsed upon :the interior mass by sucking up, and thus producing outward pressure of the atmosphere."—(Pellatt.) An interesting ball is in the collection, which a dark purple glass; covered with air bubbles, is enclosed in a transparent glass of another character.

"Millefiore is more rectular in design than the ball, but of the same character. It was formed by placing lozenges of glass, cut from the ends of coloured filigree canes, ranging them in regular or irregular devices, and encasing them in transparent glass."—(Pellatt.)

Sehmelz Glass, the character of which may be seen in the specimens- at the southern end of the case, was, formed by welding together variously-tinted glasses until the colours became irregularly blended, and the mass assumed somewhat the appearance of a variegated marble.

The Venetian Plate and another specimen of opaque glass appear to resemble in many respects Reauranr's porcelain (p. 62)..

Ancient German Glass. Venetian Enamel. Etched Glass, &C.

Case 52.

Among the specimens in this case, the arrangenient of which is not yet complete, attention may be especially directed to the interesting examples of early German glass. The tall cylindrical beakers, ornamented with escutcheons and other designs in opaque enamel colours, were peculiar to Germany during the sixteenth and seven; teenth centuries; and two of the specimens before us bear the date 1655. A smaller drinking glass, with a delicately executed painting in brown camaleu; furnishes an example of the

This case also contains a series of modern Venetian enamel cakes (p. 71), and a collection of glass beads used in the African and Indian trades. The art of making glass beads was first discovered at Murano, where the trade is still great; it is stated that they make 200 different shades of colour. Hem also will be found pieces of enamelled glass, formerly manufactured at Bristol; and some examples of painted and etched glass, &c. Etching on glass is Commonly effected by covering the glass with a coating of wax, and then with a needle removing it along'the lines to be etched. The drawing being formed, the glass is exposed to the action of hydro. fluoric acid, liberated from fluor-spar by the action of sulphuric acid and heat.

The remaining objects in this case are for the most part sufficiently explained by the accompanying labels..

Modern Ornamental Glass

Pedestal-case 47. Frame of Coloured Glasses near Case 53.

In Case 47 will be found one example which can scarcely be associated with the others as modern. It is a coloured goblet of engraved glass, formerly used by His Majesty Charles II. Through Sir Robert Gayer, one of his courtiers, it came into the possession of the Hodgson family. As showing the make and the engraving of glass in the 17th century this specimen is interesting.

Engraved Glass.—Some very fine specimens are shown. The ordinary tools used in engraving glass are discs of copper, some as large as a halfpenny, and others mere copper pencils which are moved by a lathe; these tools are smeared with oil and emery. The hard grains of the polishing material penetrate the mass of the soft metal during the process, and form a species of file, which in revolving cuts into the softer glass.

Yellow Glass.—The fine yellow on the specimens in the case are produced by silver; the yellow of the ordinary glass for ornamental windows may be produced by charcoal, iron, or antimony. (See frame of coloured glasses.)

Canary Yellow, or Uranium yellow, is the result of the combination of the oxide of uranium with the flint glass. This glass has some peculiar optical properties. If we look through any thickness of a coloured mass it is purely yellow, but if we look at any surface of it upon which the light falls it appears green. This phenomenon is possessed by uranium glass, in common with a solution of sulphate of quinine, an infusion of horse Chesnut bark, and some varieties of fluor-spar. The investigation of this peculiar dichroism was first entered on by Sir John Herschel, who observed that the effect was confined to the first surface of the body, and hence he spoke of it as epipolism; but the thorough examination of the subject was reserved for Professor Stokes, who shows that the rays thus rendered visible to us do not belong to the ordinary prismatic spectrum, having a much higher degree of refrangibility than any of the Newtonian rays. To distinguish those rays Professor Stokes proposed, as they are very beautifully shown by fluor-spar, to give them the name of fluorescent rays.

Ruby and Red Glass.—The finest reds on the vases, &c., are produced by the purple of Cassius, which may be regarded as a stannate of tin with a stannate of oxide of gold; or by a solution of gold in aqua regia (nitro-hydrochloric acid).

The Bohemian ruby is thus prepared :—a preparation called schmelze is made; it is composed of silica 500, minium 800, nitre 100, calcined potash 100. The gold solution contains 155 grains of gold in a quart of aqua regia, which is then mixed with five times its bulk of water; A- of this gold solution is mixed intimately with 512 parts of schmelze, 48 of borax, 3 of oxide of tin, and 3 of oxide of antimony, all in a state of fine powder. The whole is then heated for 12 or 14 hours in an open crucible placed in a glass furnace, and then suffered to cool in an annealing oven.

The ordinary red glass is produced by copper. The sub-oxide of copper possesses a colouring power of remarkable intensity, the smallest quantity reddening glass so deeply as to render it almost opaque —hence glass is usually only coated or flashed with the red glass produced by the sub-oxide of copper. Glass containing sub-oxide of copper does not exhibit its colour on leaving the crucible; it is, in the first instance, nearly colourless, with a slight tinge of green, but it becomes deep red when, after having cooled, it is heated a second time at a lower temperature. H. Rose supposes this curious phenomenon to be due to the formation of an acid or neutral silicate at a high temperature, and that the subsequent softening at a low temperature causes the decomposition of this compound, and a separation of some sub-oxide of copper which colours the glass.

Many examples of flashing, or spreading one colour upon another over white glass, are in the case. By cutting down through those layers to different depths, a very ornamental appearance can be produced. (See also Case 54.)

Some common red glass is produced by iron.

Amethystine Glass is produced by the peroxide of manganese.

Green Glass is obtained by the protoxide of iron, but a finer colour by the oxide of copper. Glass, coloured green by oxide of copper, has a remarkable power in stopping back the solar heat-rays. Melloni found that an apple-green copper glass, made in Italy, prevented the permeation of at least 80 per cent. of the heat rays. I discovered that the smallest quantity of the oxide of copper, in glass free from manganese, possessed the property of stopping all the parathermic rays : these are rays of low refrangibility, found below the red rays of the Newtonian spectrum. To these heat rays the scorching of plants is especially due.

Glass prepared by Messrs. Chance, Brothers, upon this principle has been employed in glazing the great palm-house in the Royal Botanical Gardens at Kew with the most satisfactory result. It has been observed that greenhouses glazed with the old green crown-glass are more favourable to vegetation than such as are glazed with the more agreeable white sheet-glass.

Blue Glass.—Oxide of cobalt is used for producing the fine blues which we see in flint glass. One thousandth part of cobalt will give a very deep blue to glass, and one twenty thousandth will impart a very perceptible tint. The preparation of smalts or zaffre will be described in a future section. (See p.108.)

Threaded Glass.—This is prepared in the manner noticed under Venetian glass (p. 67).

Millefiore.—Examples of these modern imitations of, and improvements on, the old Venetian are shown; and a specimen exhibiting the manner in which the sections of canes are disposed previously to their being enclosed in a mass of transparent glass, accompanies the specimens.

It will be evident to all, that having once enclosed these coloured canes in a mass of glass, it can be readily formed into tazze or vases, as shown in the finished examples in this case..

Artificial Gems

Strass, so called after its inventor, is a glass possessing in the highest degree purity and transparency, combined with the greatest possible lustre. It is a mixture of quartz, boracic acid, purified caustic potash, and a large proportion of oxide of lead, introduced in some specimens of Strass as red lead, and in others as white lead. With perfectly pure and colourless Strass, the colouring agent is combined—the following being a few examples :—

Topaz, antimony and gold; Ruby, purple of Cassivis; Emerald, oxide of copper or chromium; Sapphire, oxide of cobalt; Amethyst, cobalt and gold; Beryl, antimony and oxide of cobalt; Garnet, gold, antimony, and manganese; Opal, bone ashes, oxide of uranium, and forge scales, or, in some cases, oxide of nickel.—(Knapp.)

Artificial Pearls

At an early period the practice of making hollow glass beads, and filling them with a pearly varnish, was adopted, Beads were thus made by some artists at Murano, but the government of Venice considered the invention too fraudulent, and prohibited its practice.

A French bead maker, Jaquin, revived and improved the. art. He observed that the small fish called in France ablette—the bleak, cyprinus alburnus—filled water in which they were washed with fine silver-coloured particles. The water on standing deposited a sediment which had the lustre of the most beautiful pearls; this led him to attempt the manufacture of pearls from it. He scraped off the scales of the fish, and called the pearly powder which was diffused through the water, essence d'orient, or essence of- pearl. He first covered beads made of gypsum with this; but as the ladies who wore them found the pearly powder left the beads, and adhered to the skin, the use of these ornaments fell off. The beads were then made of glass—a glass easily melted and made a little bluish, being drawn into tubes, which were- called girasols (the word signifying opal). From these tubes hollow globules were blown, and they were then covered on the inside with a solution of isinglass and the pearl essence, which was blown in warm and spread over the internal surface by rapid motion. When dry, the globules were filled with wax, bored through with a needle, and strung on threads. These beads are still made of all shapes and sizes, and many of the most perfect imitations are sold at good prices. The bleak is a fish of about four inches long, caught only in fresh water; to obtain a pound of scales, 4,000 fish are necessary, and these do not produce four ounces of pearl essence, to preserve which sal ammonia in solution is used. The optical effect is produced in the same manner as in the real pearl, the grooves of the pearl being represented. by the inequalities of the laminæ formed by those particles removed from the scales of the fish..

Heavy Glass

This is a silico-borate of lead, prepared by Professor Faraday. It is exceedingly interesting, as being the substance in which the influence of magnetic force in altering the refraction of a ray of light was detectd, and which also exhibits very remarkable diamagnetic properties.

Aventarine Glass. See also Venetian examples and No. 596 in Horse-shoe case.—This is an ordinary glass, which owes its colour to the sub-oxide of copper; and the brilliant laminnæ are probably metallic particles, produced by the addition of some powerful reducing agent to the melted copper glass..

Enamels

Table-cases 1, 56, and 43. Model of Tomb No. 10.

Enamelling, or the process of covering metals or stones with a vitreous substance, or of running enamels into portions which have been previously removed by a graver, is of high antiquity. There Was but a step from the enamelled bricks of Babylon to the enamelled bronzes of the Romans, or the shrine enamels of the Byzantine' empire.

A series of historical specimens illustrating this art will be found in Table-case 1, at the western corner of the staircase. Commencing with some Roman enamels found near Eden in Cumberland, we have next a Byzantine enamel on gold of the 11th century, being a portion of the "gold altar" front obtained from Constantinople by the Doge. Pietro Orseola. This is followed by a reliquary of the 13th century, enamelled in the

In the 14th century we have a Priket candlestick from Dijon in champ levé enamel, and a monstrance ornamented in a different

Enamel painting—properly, painting on enamel—is fully illustrated in Case 56. The white cake enamel used as the painting ground, and the beads and pipe employed as a flux, are all manufactured in Venice. These appear to consist of about tenpartsof lead and three parts of tin, converted into oxide by heat and exposure. To the mixed oxides are added ten parts of quartz and two parts of common salt, and the whole fused together. The enamel being reduced to powder, is spread over a plate of copper or gold and exposed to a strong heat; the enamelled plate is then coated with flux, and again fired and ground down, as shown in the specimens. This is the surface upon which the enameller has to work. He takes metallic oxides, these he mixes with the flux and paints his picture. An enamel painting has to pass many times through the fire, consequently great care is required in this part of the work.

No fault can be corrected, the fire fixes the colours as applied, and whether, good or bad they are unchangeable. The various colours employed are shown.

Mr. Hone was probably the first who ventured to paint large enamels : a small work by this artist, of the date 1749, is in this case. Mr. H. Bone, R.A., by whom there are several beautiful works, exceeded all before him in the size of enamel paintings, his Bacchus and Ariadne, the original of which is in the National Gallery, measuring 18 inches by 16½. The portrait of. Sir Henry De la Beche was painted on enamel from the life by Mr. H. P. Bone, and presented by him to the Museum.: this, from the difficulties of the art, is not often attempted. There are other examples by the same artist.

The modern French Limoges enamels, and another, together with the portrait of the celebrated Saussure, by Constantin, painted in 1845 will show the state of this art on the Continent.

Model of the Tomb of William de Vallence (No. 11).—William de Vallence, senior Earl of Pembroke, half brother to Henry III., died ha 1304, and was buried in Westminster Abbey. His tomb was decorated in the costly

Chinese Enamels, Glass, &c.—In Case 43, on the eastern side, will be found some specimens illustrating the art of enamelling amongst the Chinese. From a very early period this nation has been in the possession of the art of enamelling metals, and of painting on enamelled surfaces. The large plaque and the bowl are examples of ancient cloisonné enamelling, differing from the champ-levg process already described, inasmuch as the outline is here formed, not of the plate itself, but of separate narrow bands of metal bent into the required shape, and attached to the ground. These incrusted enamels are accompaniel by several examples of superficial enamelling; and with these are associated various specimens of Chinese pottery and glass in course of arrangement..

Mosaics

Table-case 46.

Portrait of the Emperor of Russia, &c. on gallery stairs, eastern side. Head of Christ, &c. on western side.

In noticing the tesselated pavement in the lower hall, the pavements of Woodchester and of Cirencester have already been named. In this case are examples of ancient Roman tesselated pavements, which show the manner in which they were constructed, and the kind of design which is usually found. Many of those Roman pavements are not only interesting as relics of this great people, but they are beautiful works of art, and they must have been the result of immense labour and great skill. A portion of a mosaic pavement found at Halicarnassus is mounted on the W. staircase.

The art of manufacturing glass mosaics was practised in old Rome, and the modern city is still the seat of this manufacture. The manufacture has, however, as might be expected, varied somewhat in character. As at present practised, thin rods of easily fusible glass of every variety of colour are prepared for the purpose. From masses of coloured glass are formed, first, slabs, and then the little rods exhibited; the artist softens these in the flame of his lamp, draws out the rod into a thick thread, and breaks off a piece of the thickness of the intended picture. The design of the picture is copied from a cartoon, and the pieces are placed in proper order on a sheet of copper, covered with a cement which serves for fixing the picture; when the whole slab is covered, the surface, which is uneven and unsightly from the unequal length of the rods, is ground and polished. After the removal of the polishing powder the interstices between the rods are filled with wax, which corresponds in colour with the different parts of the picture. Some large examples of modern mosaic work are near the glass on the east side. The largest known mosaic picture is taken from the Lord's Supper of Leonardo da Vinci, which is 12 feet high, and twice as long; it is said to have occupied eight or ten artists daily during eight years. The Byzantine mosaics differ from the others only in the artistic character of the productions. A larger example of this work is the Head of Christ, on the western staircase : whilst on the opposite side are two modern mosaics, of large size, one the portrait of the late Emperor of Russia, executed in 1828, and presented to the Museum by the Cavaliere Barbieri.

The opus incertum (Terrazzo or Pavimento Veneziani) is in common use in the north of Italy for floors, the colours being given to the lime by ochres. The lime ash floor of England is another variety of the same composition.

The pieces from the walls of Pompeii show the kind of stucco used, and the general character of the paintings in the houses of that city. It will be seen that these are not in fresco, but ordinary paintings on the cement employed..

Babylonian Cylinder and Amulet

Table-ease 46.

From the excavations made during the researches of Layard, Rawlinson, and Loftus have been obtained numerous engraved cylinders, seals, &c., chiefly of natural minerals, such as rock-crystal, agate, carnelian, serpentine, lapis lazuli, &c. The Babylonian cylinder and the amulet were both obtained from the late Mr. W. Kennett Loftus. These cylinders are beautifully polished, and around them are very finely-executed intaglio engravings of human figures or deities, together with the arrow-headed characters. These cylinders are so excessively hard as to have necessitated the use of well-tempered graving tools. Such tools of hardened steel have been found, and were in course of transmission to this country, but were unfortunately lost by the overturning of a barge in the rapids of the Euphrates. The cylinder and amulet were submitted to chemical examination by Mr. John Spiller, in the metallurgical laboratory of the Institution. The result of that examination proves the cylinder to be native magnetic oxide of iron, and the amulet to be haematite..

The Mineral Collection

The Mineral Collection of this Museum is arranged in the series of 56 wall-cases around the principal floor, and in the large horseshoe case occupying a prominent position in the central area. Apart from this general collection, there will be found on the same floor a few mineral specimens, which have been isolated on account either of their size or of some special interest connected with them. As each specimen is distinctly labelled, and moreover as a special catalogue of the minerals is published, it will only be necessary in the present guide to give such a popular description of the collection as shall render it intelligible and interesting to the general visitor.

The non-metallic minerals occupy the central horse-shoe case, and are described at p. 133; while the ores or metalliferous minerals are placed in the series of wall-cases, and arranged in the following order:—

British ores (west side)	Cases 1 to 14, p. 74.
British ores (east side)	Cases 43 to 58, p. 100.
Foreign ores	Cases 15 to 23, p. 81.
Colonial minerals	Cases 87 to 42, p. 95.
Mineral veins	Cases 24 to 36, p. 90.

Each of these sections of the collection will now be brought separately under notice..

British ores

1st Division. Western Side. Wall-cases 1 to 14.

Copper

Case 1. —The copper mines of this country are somewhat recent. In the time of Elizabeth there is an Act of Parliament forbidding the exportation of calamine,—as retaining it may occasion large quantities of rough copper to be brought in for the manufacture of brass, latten, bell-metal, pan-metal, and shrof-metal. A century since, several tin mines were abandoned when the miners came to the "yellows;" this was the yellow copper ore, and their saying was that the "yellows cut out the tin." This shows the small estimation in which copper ore was then held. In 1865 there were in Cornwall and Devon about 180 mines selling copper ore at the public sales—" ticketings." ,These are so called from the circumstance that the sale is conducted in silence; the ore for sale is announced, and the bidders write the price they offer on a ticket, which is folded up and silently put into a glass. The "clerk of the ticketings" opens these and proclaims who is the highest bidder. The accounts of these sales are published in "ticketing papers." The value of all the ores has been previously determined by the assay of samples," one pound in weight, which are taken by all the parties concerned from the heaps prepared for sale at the mine.

The series of copper-producing minerals commences with the valuable native or malleable copper. In many of the Cornish mines this mineral is not unfrequently found in company with various copper ores; the largest masses occurring in the serpentine of the Lizard district, of which a magnificent example will be seen in the hall (No. 165, p. 38). The Irish and Scotch specimens on the top shelf Show its occurrence in thin plates in the fissures of trap-rock; whilst many other examples in this case exhibit the characters of the crystallized varieties.

From native copper we pass to the sub-oxide cuprite or red copper ore, a mineral containing nearly 90 per cent. of copper. It occurs often in octohedral or eight-sided crystals, of a fine ruby colour and high lustre, and occasionally assumes delicate capillary or hair-like forms, known to the miner as "plush copper ore," and to the mineralogist as chalcotrichite; whilst the less pure brick-red massive varieties of cuprite are often distinguished as tile ore. Melaconite or black oxide of copper, is a dull blackish mineral substance resulting from the decomposition of other copper ores.

Case 2.—Well known from its employment sometimes for ornamental purposes, and sometimes as a pigment, the beautiful mineral called malachite or green carbonate of copper, naturally claims attention. In this country it is found only in subordinate quantity, rarely presenting distinct crystalline forms, but occurring usually in mammilated, botryoidal, and stalactitic masses. Its recent formation is well illustrated by the specimens from Wheal Leisure, in which particles of, sand are cemented, by this mineral. With these specimens may be noticed the examples of cupriferous sandstone and conglomerate from the lower keuper of the neighbourhood of Alderley Edge : the copper is dissolved out by treating the sandstone with hydrochloric acid, and from the solution of chloride of copper thus obtained the metal is precipitated by scrap iron. Among the carbonates of copper will be- found a few specimens of azurite or blue malachite, and on the same shelf are some samples of chrysocolla, or silicate of copper.

Among the Cornish arsenates of copper, attention may be directed to the beautiful sky-blue octohedrons of liroconite; the , dark blackish-green crystals of clinoclase; the bright emerald-green six sided plates of copper mica; the dull green crystals of olivenite, and the fibrous variety of the same species known, from its structure; as wood arseniate of copper. The condurrite of Dr. Faraday appears to be an impure cupric arsenide. With these are associated seine specimens of libethenite, or phosphate of copper, and a sample of the new Cornish sulphate of copper called langite.

From these somewhat rare minerals we turn to the important ore known as copper glance, vitreous copper, or redruthite, a disulphide of copper containing 80 per cent. of metal. From St. Ives and St. Just several finely crystallized specimens are exhibited, and in some of them will be recognized the peculiar six-sided forms which have suggested the popular name. of "nail-head copper ore."

Cases 3, 4, 5, 6.—Far exceeding all other copper ores in its importance to this country is the well known copper pyrites,—the yellow ore of the miner, and the chalcopyrite or towanite of the mineralogist. This mineral, which is a sulphide of iron and copper, is usually found massive, but it occasionally occurs crystallized, its characteristic forms being well shown by the specimens in Cases 3 and 4. The fine mammillated and botryoidal masses from Cornwall and Devon are known to the miners as "blister ore;" whilst the iridescent tarnish on the surface of other varieties of copper pyrites has suggested the name of "peacock ore."

In this country.copper ore is obtained from the mines of Cornwall and Devonshire, from some mines in Ireland, a few in Wales, and some in the northern counties. Each of these localities has its representatives in the collection, and the produce of the several mines will be found in the "Mineral Statistics" compiled by the author of this Guide.

Case 7.—Allied in chemical composition to copper pyrites, with which, indeed, it was long confounded, is the species called bornite purple copper ore, or erubescite. To our Cornish miners the mineral is commonly known as "horse flesh ore," whilst frequently it passes under its German name of Buntkupfererz (variegated copper ore), In addition to the fine purple masses from Ireland and Cornwall; there will be found several crystallized specimens exhibiting its cubic forms; these crystallized varieties are exclusively British, being confined to the mines in the neighbourhood of Redruth.

The crystallized specimens of the rare Cornish mineral tennantite —a sulphide of copper, iron, and arsenic, of somewhat rare occurrence—are followed by those of Fahlerz, or grey copper ore, a species which, although uncommon in this country, occurs near Liskeard in fine crystals, which exhibit well the characteristic tetrahedral forms which have gained for this mineral the name of tetrahedrite. The series of copper ores is brought to a conclusion by the specimens of endellionite or bournonite, an antimonial sulphide of copper and lead, of which, some magnificent crystals of well-defined rhombic form, aid remarkably high lustre, are exhibited from Liskeard in East Cornwall..

Tin

Case 8.—From the earliest recorded times Britain has been famous for its tin. From. Cornwall the Phoenician navigators took this metal to Tyre and Sidon; and, in all probability, the bronzes of Assyria and of Egypt were made with the tin raised by the ancient Britons. The Cassiterides, or Tin islands of the historian, have been though to be the Scilly islands; but as there is no evidence that any tin was ever found in Scilly, and certainly there is none there at present, this idea must be relinquished. In all probability the name was given by the early navigators to the western part of England, over which is spread the tin formations, and where we find evidences of mine-workings of the highest antiquity.

Diodorus describes the trade with Cornwall, "Bolerion," for tin, and mentions the place of shipment,—the Ictis, an island adjoining to Britain. He says, "It is something peculiar that happens to the islands in these parts, lying between Europe and Britain; for at full-tide, the intervening passage being overflowed, they appear islands; but when the sea returns a space is left dry, and they are seen as peninsulas." Mr. Wright and the late Sir G. C. Lewis suppose the Isle of Wight to be the Ictis, but it does not fulfil any of the conditions of the geographer; whereas St. Michael's Mount and Looe Island in all respects agree with the description. Diod-orus evidently speaks of more than one island, and there is abundant evidence to show that both St. Michael's Mount and Looe Island would have been convenient shipping ports for the tin raised around the Mount's Bay and Land's End, and that which has been obtained from the old tin mines around St. Austell.

The produce of tin in Cornwall has, for more than a century, observed a remarkable constancy. In 1750 about 2,000 tons were produced; this rose to above 3,000 in 1817; to more than 4,000 tons in 1827; and it oscillated between 3,000 and 4,000 until 1841. In 1866 the quantity of tin ore or "black tin" raised amounted to 15,080 tons, producing 10,000 tons of metallic or "white tin." In spite, however, of this high produce, British tin mining is at present in a most unsatisfactory condition, owing to the extremely low prices realized.

Tin is almost exclusively obtained from cassiterite or tin-stone, a peroxide of tin containing nearly 80 per cent. of metal. In the granite and clay-slate of Cornwall and West Devon this mineral occurs in veins, and is readily separated from its gangue and from most of its accompanying minerals, by taking advantage of the great density of the ore, With the specimens of tin-stone will be found a very curious set of pseudomorphous crystals, or those which have the composition of one mineral and the form of another, in which the original felspar of a porphyritic granite has been removed, and the oxide of tin has taken its place, preserving still the true felspar form. The subject will again be referred to at p. 93.

During the lapse of long geological periods the stanniferous or tin-bearing rocks have been worn down by the combined influences of air and of water, and with the disseminated minerals, and the contents of the mineral lodes, have been carried down to the lower grounds, and arranged in obedience to the laws of gravitation. Tin was thus deposited in beds over the underlying rocks in the valleys, being covered up to various depths with lighter matter. Specimens of stream tin are exhibited from several Cornish localities, and with them are some examples of the fibrous varieties of tin-stone, known from their peculiar structure as "wood tin," and "toad's-eye tin." "Streaming," or washing these deposits for tin, is now nearly extinct.

Case 9.—On the first shelf of this case are placed several samples of stannine, known also as tin pyrites and bell-metal ore; a mineral containing sulphur, tin, copper, iron, and frequently zinc. This mineral is confined in Cornwall to a few localities, where it has been raised as a tin ore to a limited extent..

Bismuth

Case 9.—This metal, which occurs usually in a native or free state, is not found in this country in any considerable quantity. In Cornwall its ores occasionally occur associated with other minerals,—with tin in St. Just, and with copper in the Redruth and Camborne mines.

In addition to the samples of native bismuth, of which some are remarkable for their brilliant lustre, will be found several specimens of bismuthine, a tersulphide of bismuth; and of the rare mineral called aikenite or needle ore, a sulphide of bismuth, copper, and lead. It is noticeable that bismuth and its ores are characterized by their extreme fusibility, melting readily even in the flame of a candle..

Cobalt and Nickel

Case 9.—The ores of these allied metals will be more fully noticed among the foreign minerals. In this country they are occasionally found in Cornwall, Cumberland, and Scotland, but the amount is neither considerable nor constant. Cobalt was formerly raised at Huel Sparnon, near Redruth, and at Dolcoath, near Carnborne; it has also been discovered in St. Just, to the west of Penzance, and has for some years been sold from the St. Austell Consols. At Coniston, in Cumberland, fine specimens of cobalt ore occur; and from the property of the Duke of Argyle, in Argyleshire, nickeliferous pyrites in some quantity was raised a few years since. In 1854 the St. Austell Consols sold no less than 79 tons of nickel and cobalt ore, but at present neither of the minerals is raised.

The principal cobalt ores are smaltine, or tin-white cobalt, and cobaltine, or silver-white cobalt; the former an arsenide, and the latter an arsenio-sulphide of cobalt, but both usually containing varying proportions of other metals. By the decomposition of these arsenical cobalt ores is produced the peach-blossom coloured arseniate known as erythrine or cobalt bloom.

Among the nickel ores, of which the principal is the di-arsenide known as Kupfernickel or copper nickel, attention may be directed to the delicate needle-like crystals of millerite or capillary pyrites,—a sulphide of nickel occurring in the cavities of the clay-ironstone nodules of South Wales..

Tungsten

Case 9.—This metal, known also as wolframium, occurs usually as a double tungstate of iron and manganese, forming the species called wolfram. Having a density corresponding nearly with that of tin-stone, it is with difficulty separated from the tin ore with which it is almost invariably associated. Oxland's process for dressing tin ores containing wolfram will be subsequently noticed (p. 106). The yellow mineral called wolframine is a tungsten ochre : whilst the rare species Scheelite is a tungstate of lime..

Tin smelting

Cases 10 and 11 are occupied by metallurgical products which will be noticed under the head of "Tin smelting" (p. 105)..

Zinc ores

Case 12.—The most widely-diffused ore of this metal is the sulphide called zinc blende, from the German blenden, to dazzle, in allusion to the high lustre which this species often presents, and which is well seen on the cleavage-faces of some of the specimens. Blende is generally associated with the ores of lead, and frequently with those of copper and tin. In a state of purity it is transparent and almost colourless (see examples); but the blende of his country isusually mixed with a variable amount of sulphide of iron, which imparts to it a dark colour, whence it is called by. the English miners black Jack. In some districts the presence of zinc is deemed by the miners unfavourable, and they speak of "black Jack cutting out the lode." In others it is thought to be a favourable indication, and we often hear that "black Jack rides a good horses"

More valuable as an ore, but much less, abundant than the sulphide, is the carbonate of zinc known usually as calamine. This mineral rarely occurs crystallized, but is usually found in deposits of mammillated, botryoidal, and stalactitic forms, of which some fine examples are exhibited from Aldstone Moor.

The hydrous silicate of zinc, known as smithsonite or electric calamine, commonly occurs associated with the carbonate, with which it is not unfrequently confounded. Attention may be directed to a fine specimen of a blue cupreous variety of this species from Cumberland..

Cadmium

Case 12.—With the ores of zinc will be found some specimens of the rare and exclusively Scotch mineral greenockite, a sulphide of cadmium occurring in yellow lustrous crystals of hexagonal form. The usual sources of cadmium and its applications will be noticed hereafter, p. 108..

Manganese

Case 13.—Although not occurring in this country in regular deposits or in very considerable quantity, the ores of manganese' have however been worked in several localities, especially at Lifton, near Tavistock, and at Launceston, at several mines not far from Exeter, in the Mendip hills, and in Warwickshire.

At the present time its extraction from British mines does not prove remunerative.

Manganese is employed in glass manufacture, and for colouring pottery. but its great use is in the preparation of chloride of lime and in the bleaching establishments. It is used in both cases for the purpose of liberating the chlorine from the hydrochloric acid or the salt (chloride of sodium) with which it is mixed for this purpose.

Pyrolusite, or binoxide of manganese, has received its name from Tipp (πΰρ) fire, and Now (λύο) to wash, in allusion to its employment as a decolouring agent in glass manufacture, and for the same reason. it is called by the French glass makers le savon des verriers.

Manganite, or grey manganese ore, is a hydrous sesquioxide, of much rarer occurrence in this country than pyrolasite; whilst the somewhat ill-defined species psilomelane is an impure hydrous oxide, usually found in botryoidal or stalactitic forms, which from their smooth surface and black colour have given the name to this species..

Uranium

Case 13.—Of this rare metal several ores are here exhibited. The oxide called pitchblende is interesting as being the mineral in which uranium was first detected; whilst the species called chalcolite and uranite are attractive by the brilliant colours of their crystals; the former of these minerals contains phosphate of copper, and the latter phosphate of lime, associated in both cases with a phosphate of uranium..

Titanium

Case 13.—In the hearths of some of the iron furnaces of South. Wales, and elswhere, there are frequently found beautiful crystals of a peculiar compound of titanium derived from the ores with which the furnaces are fed. But although recent researches have shown that titanium is a metal much more widely diffused than was formerly supposed, the distinct native compounds of the element are, nevertheless, far from numerous. In the state of oxide, titanium occurs in three totally distinct forms, of which specimens are here exhibited. The long prisms of rutile running through the quartz of Perthshire, the fine tabular crystals of brookite associated with albite-felspar at Tremadoc, and the small pyramidal crystals of anatase, are simply different forms of the same oxide of titanium; the chemical composition being in all, cases identical.

Titanium has been employed for improving the quality of iron and steel, and for the preparation of certain pigments..

Vanadium

Case 13.—The vanadiate of lead: called vanadinite, found not unfrequently in the lead mines of Wanlock Head in Dumfriesshire, will be again noticed among the lead, ores (p. 101)..

Molybdenum

Case 13.—The chief source of this rare metal is the mineral called molybdenite, a sulphide .of molybdenum, somewhat resembling plumbago in appearance..

Chromium

Case 13.—This metal is tolerably abundant in the form of chromate of iron, constituting the mineral called chromite or chrome iron ore. It usually occurs in serpentinous rocks, and is especially abundant in the serpentine of the Shetland Isles.

The compounds of chromium are extensively employed in the arts, principally in the preparation of pigments..

Antimony

Case 14.—At one period considerable quantities of antimony ore were raised in Cornwall, and some in Dumfriesshire; but now the principal part of our supply of antimony is from Borneo and the East Indies.

The chief ore is the tersulphide of antimony, called indifferently antimonite, stibnite, and antimony glance. By the side of the samples of this ore are a few specimens of jamesonite, a sulphide of antimony and lead, of which enormous lodes occur in Devonshire; but the difficulty of separating the lead and antimony from each other renders them valueless.

By the decomposition of jamesonite is produced the yellow antimoniate of lead called bleiniere.

British Gold

Case 13.—There is no metal found more widely diffused than gold, but it has rarely been found in these islands in sufficient quantities to render the search for it remunerative.

In the tin streams of Cornwall gold has been and is still found. The streamers find occasionally small particles of gold connected with the tin ore, which they pick out and preserve in a quill. Occasionally a moderate-sized piece of gold has been discovered. One fine specimen from Carnon stream is in this collection, and some of the smaller grains. Gold has been found in Devonshire, near North Molton, and attempts have been made from time to time to work mines supposed to produce it. In every such attempt the result has been the total loss of all the money invested.

During the last quarter of a century public attention has, from time to time, been directed to the gold-bearing district of Merionethshire. The excitement which a few years back attended the workings at the Vigra and Clogau, between Dolgelly and Barmouth, led to the opening up of numerous other gold mines in adjacent districts, but in most cases the operations have been abandoned as unremunerative. The following extracts from the "Mineral Statistics" will show the amount and value of the gold obtained from the Welsh hills during the last five years :—

	Gold	Value £
1861	2,886 ozs.	10,816
1862	5,299 ozs.	20,390
1863	552 ozs.	1,747
1864	2,336 ozs.	9,991
1865	1,664 ozs.	5,824
	12,737 ozs.	£48,768

Among the specimens are several examples of native gold from Wicklow, the discovery of which in the last century produced considerable excitement.

In 1795 lumps of pure gold were picked up in a valley on the flank of the mountain called Croghan Kinshela; and as the natural consequence of such a discovery, crowds of the country people quitted their ordinary avocations and rushed to the gold streams of Wicklow. During six weeks some hundreds of gold seekers appear to have collected a considerable quantity of the precious metal. Then a commission, consisting of Messrs. Mills, King, and Weaver, directed the operations of streaming, and until the outbreak of the rebellion in May 1798, the works appear to have been remunerative. When. in 1801 these works were again brought into active operation, not only was the process of "streaming" still pursued, but an attempt was made to discover the lodes from which the gold had been derived. A level was driven 178 fathoms into the heart of the mountain, and the costeaning* <span

Gold has also been found in Scotland, but no specimens of Scotch gold are in these collections. Pennant says : In the reign of James IV. and V. of Scotland, vast wealth was procured in the Lead Hills, from the gold found in the sands washed from the mountains; in the reign of the latter not less than to the value of 300,000l. sterling." This is evidently the exaggerated report of some parties who were desirous in Pennant's time, as they have been since, of reviving the search. The Bannatyne Club published in 1825 a curious manuscript, "The Discoverie and Historic of the Gold Mynes in Scotland, written in the year 1619, by Stephen Atkinson," of which a copy is in the library of the establishment. In this work several districts are named over which gold has been discovered, and many statements, evidently the exaggerated dream of a sanguine projector, are made to convince the King, who is compared to King Solomon for wisdom, that public money might be spent with advantage in the search..

Silver

Case 13.—Silver ores are not discovered in any large quantity in this country. We obtain annually a large amount of silver from our lead ores; this will be noticed in a future section.

Native silver, silver glance, red silver ore, and horn silver are exhibited from several of our Cornish mines, but it seems desirable to defer notice of these minerals until describing the more typical specimens from foreign localities (p. 87.)

A series of ores is exhibited from the little isle of Sark, where fiver mines were for some time worked; but not being sufficiently remunerative, the operations were at length discontinued..

Arsenic

Case 13.—In the lower part of this case are several specimens of mispickel or arsenical iron pyrites, an arsenio-sulphide of iron frequently found in our western mines, and commonly employed as a source of "white arsenic," the preparation of which will be subsequently described. (See p. 107.)

With this series terminates the first division of the British ores, the remaining section,—including the ores of lead and iron,—being arranged in the recesses on the opposite side of the room. As, however, it appears desirable to continue the description of the wall-cases in their natural sequence, the collection of foreign ores occupying the cases adjacent to those just described will now be brought under notice, whilst the description of the second division of British metallic minerals will be reserved until reaching the opposite side of the Museum. (See p. 100.)

Foreign ores

Wall-cases 15 to 23..

Copper

Case 15.—Among the specimens of native copper which head the series of copper-bearing minerals, attention may be especially directed to the fine samples from the remarkable deposits around Lake Superior. There exists abundant evidence to show that these deposits were worked at a very remote period; and one of the stone-hammers used by the primitive miners will be found in Case 46. All tradition however of these early workings had been lost, and the existence of the metal was known only by the occurrence of masses of copper on the shores of the lake. In 1845 operations were commenced at the Cliff Mine, and these were rapidly followed by the opening up of numerous other workings. The copper-lands on the south side of the lake,—including the Keeweenaw Point,

Portage, and Ontonagon districts,—consist of Lower Silurian sandstones and conglomerates, with a central belt of trap-rocks traversed by copper-bearing veins. The metal is also found disseminated. through the beds of trap, and occasionally through the sandstones and conglomerates; and it likewise occurs in contact-deposits between the trap and the neighbouring rocks. The chief portion of the copper is native, and occasionally, from the manner in which this is mixed with quartz and carbonate of lime, large masses are broken out with tolerable ease; but when, as is frequently the case, a mass of several feet in thickness presents itself, there is no mode of extricating it from the rock but by the slow, process of cutting it with _cold adsvls. This native copper contains a considerable portion of silver; in, some specimens the silver crystallizes about the copper in a very beautiful manner. The two metals do not in general occur alloyed mah each other, but the silver is scattered through the copper in such a manner that each metal remains chemically distinct from the other. (See specimens in Case 22.) Copper also occurs at the Lake. Superior mines in the form of oxide, silicate, sulphide, and arsenide.

While studying the specimens in the case before us, attention should be directed to a series from this locality presented by Mr.. Bauerman, and placed in Case 36.

In addition to the Lake. Superior series, there are exhibited other specimens of native copper, from the mines of Russia, Tuscany, Cuba, and. Chile.; whilst of the valuable ore cuprite or red oxide of, copper, samples are exhibited from several localities in Russia, and from Rhenish Prussia, Hungary! Cuba, and South America. The detached crystals of cuprite from Chessy, near Lyons, are notable for their large size and perfect form, but the mineral is disguised, by a thin coating of green carbonate.

Case 16.—The greater part of this case is occupied by specimens of the beautiful mineral malachite or green carbonate of copper, of which the celebrated Russian deposits have contributed numerous fine examples.

The richest masses of malachite have been found about 100 miles south of Bogoslovsk. Some idea of the magnitude of the masses in which malachite sometimes occurs may be formed from Sir R. Murchison's account of a lump discovered at Nijny Tagilsk, at a depth of 280 feet:— "The strings of green copper ore occurring at intervals were followed downwards, when, increasing in width and value, they were found to terminate at the base of the present mines in an immense irregularly-shaped botryoidal mass of solid malachite, the base of which had not been reached." The summit of this mass is described as being 18 feet long and 9 feet wide. When Sir R: Murchison visited it in 1843, it was calculated to contain not less than half a million of pounds weight of pure and solid malachite. On the formation of this malachite Sir. R. Murchison has some appropriate remarks, which apply with equal Force to the carbonates of copper which occur in South Australia:—

"The geological interest attached to this mass (the above named) lies in the indication it affords, that the substance called malachite has been formed by a cupriferous solution which has successively deposited its residue in a, stalagmitic form. Mutatis mutandis, this mass has only to be viewed as formed of calcareous spar, and it presents every one of the features so well known to those who have examined stalactitic grottoes, with their stalagmitic floors in the clefts and caverns of limestone, or still more those large masses of tufa, which have proceeded from calcareous wells. Whenever a portion of the malachite has been broken off, the interior is seen to consist of a number of fine laminae (a fascieulus of radio-concentric globules), which invariably arrange themselves equally around the centre on which they have been formed, and are adapted to every sinuosity of the pre-existing layer; here presenting a dark line—there a bright and light one, just as the solution of the moment, the day or the hour, happened to be more or less impregnated with colouring matter. Besides round concretions, sometimes almost spherical, and also depressions of the surface, the under sides of this malachite are singularly analogous to that of any large mass of calcareous tufa, in presenting pendant finger-shaped stalactites, which are also composed of concentric lamina The external surfaces of these concretions are frequently covered with a black ore of manganese, which usually falls off on being touched. * * * On the whole, we are disposed to view it as having resulted from copper solutions emanating from, all the porous, loose, surrounding, mass-; and which, trickling through it to the lowest cavity upon the subjacent rock, have in a series of ages produced this wonderful subterranean incrustation."—The Geology of Russia, p. 374.

Passing from the green to the blue carbonate of copper, attention may be invited to the groups of finely-formed brilliant crystals from the now exhausted copper mines of Chessy, about 20 miles N.W. of Lyons : from this famous locality the species has received the name of Chessylite.

The dark blackish-green crystals of libethenite, a hydrous phosphate of copper, and the bright emerald-green euchroite, a hydrous arseniate of copper, both from Libethen in Hungary, are placed by the side of some fine mammillated specimens of the cupreous phosphate called ehlaite, and a sample of the rare Russian mineral demidovite, a siliceous phosphate of copper.

The mineral called atacamite, from the desert of Atacama between Peru and Chile, is an oxychloride of copper occasionally found in sufficient quantity to be worked as an ore, and occurring also as a volcanic product on certain Vesuviau lavas.

In the lower part of this case are some fine specimens of copper glance and bornite, or purple copper ore, from the remarkable deposits of Monte Catini in Tuscany. These minerals occur, with other copper ores, in the form of nodules and irregular masses embedded in a steatitic matrix in a dyke of tertiary serpentine_; or "gabbro verde," associated with the metamorphic rock called "gabbro rosso." The principal part of the ores from the prosperous mine of Monte Catini is smelted at Briglia, near Prato.

Case 17.—On the upper shelves of this case are examples of copper glance and purple ore from various localities, the fine masses of purple copper from Chile being especially noteworthy. A large sample of bornite from Greenland is placed in the hall, No. 27.

The important German deposit of Kupferschiefer, or copper-slate, is represented by several specimens. This remarkable stratum lying at the base of the Zechstein, or magnesian limestone, extends uninterruptedly over a very wide area, and in spite of its thinness and its Poverty of ore is successfully worked at several points, especially at Mansfeld in Prussian Saxony. Occasionally the cupreous schist contains the fossil remains of certain Permian fish, and a fine specimen of one of the most. common species of Palæoniscus is here exhibited. Tho metallurgical treatment of the Kupferschiefer will be subsequently noticed. (See p. 104.)

Case 18. —The series of iron ores commences with several specimens of magnetite, or magnetic iron ore, from the hills of Blagodat in the North Ural; but the most interesting samples of this mineral are those from the famous iron mines of Sweden. "The region of the mines "—so called in Sweden—occupies the whole breadth of the country from the boundary of Norway to the Gulf of Bothnia, its northern boundary being a line drawn from Glommen through Lake Liljan to Soderham, its southern boundary lying about lat. 59° N. The area of this district is 16,000 square miles. The best iron is obtained from the Dannemora mines in Upsala Lin, of which upwards of 3,000 tons are annually received into England, and employed at Sheffield and other places for making steel. The Dannemora mines are three in number, very distinct and parallel to each other; they are explored through a length of more than 1,500 yards, and to a depth of about 80 yards. The annual produce of the Dannemora mines is about 25,000 tons of ore. For a description of Swedish iron-smelting, see p. 130.

The series of iron ores is interrupted by a small number of titanium minerals, among which may be noticed the unusually large crystals of rutile from the United States, and the oblique crystals of sphene from Grisons and the Tyrol.

Returning to the iron-producing minerals, we find several shelves occupied by examples of the different varieties of haematite or red iron ore. Among these the eye will be especially attracted by the brilliant lustre, and in many cases by the iridescent tarnish, of the crystallized variety called specular iron ore, of which the Isle of Elba has contributed some beautiful examples. The Elban specular ore, celebrated from remote antiquity, occurs in enormous deposits on the eastern side of the island, where it has long been worked by large open excavations, principally at Rio; whilst the rich veins of magnetic ore associated with haematite at the famous Loadstone Mountain, or Monte Calamita, have recently invited exploration. The occurrence of specular iron ore in the craters of volcanos will be noticed at p. 125.

Case 19.—Brown iron ore, or hydrous peroxide of iron, occasionally called "brown hæmatite," is a very abundant and widely-diffused mineral, resulting frequently from the decomposition of other iron ores, and often associated with the ores of manganese. The fine stalactitic and botryoidal forms of the Russian specimens, and the fibrous structure of many of the German samples, sufficiently show the characters of the purer varieties; whilst the friable earthy forms passing into ochre are illustrated by examples from various localities. The pure crystallized hydrous sesquioxide of iron, of definite composition, has been separated as a distinct species under the name of göthite.

The bog iron ore is an interesting variety of brown ore, formed in low marshy ground from the decomposition of other iron ores. It always contains a large proportion of impurities, phosphoric acid being often present to a considerable extent.

Brown iron ore appears in many cases to have resulted from the alteration of the carbonate of iron, to which species we now pass. This valuable mineral, called indifferently spathose iron ore, chalybite, siderite, and sparry iron ore, frequently occurs crystallized in rhombohedral forms, which commonly present curved faces, well seen in the fine specimen from Dauphiné; whilst the large crystals from Hüttenberg in Carinthia, exhibit the change of this mineral into brown iron ore by the elimination of carbonic acid and the absorption of oxygen and water. Immense beds of spathose ore are found in Styria, forming the Erzberg, a mountain from which it was probably dug by the Romans. In Carinthia an excellent ore of this kind exists, from which iron and steel of the first quality are produced, and most of the Austrian iron and steel is derived from this ore. Valuable deposits of spathose ore occur in the Devonian rocks in the neighbourhoodneigghbourhood of Siegen in Rhenish Prussia, including the celebrated Stahlberg, near Müsen. The remainder of this case is occupied by iron ores of far less importance than those already mentioned. Among these may be noticed the Elban silicate of iron, called ilvaite or lievrite; the common arsenio-sulphide of iron, or mispichel; and the rarer arsenide of iron, from Reichenstein, termed lolingite, the treatment of which for the separation of gold is described at p. 107. The large pentagonal dodecahedrons of iron pyrites from Elba, and the fine bronze-coloured crystals of pyrrhotine, or magnetic pyrites, from Brazil, also deserve attention; and these, with a small collection of chrome iron ores, complete the series..

Manganese, Bismuth, &c.

Case 20.—Examples of the rarer oxides of manganese called haus-marnite and braunite are placed by the side of the oxides known as pyrolusite, manganite, and psilomelane (p. 78), minerals which are largely raised in Spain, Nassau, Thuringia, and the Hartz. With these oxides are grouped specimens of the pale pink carbonate of manganese called diallogite, or manganese spar, and of the rose-red silicate termed rhodonite; whilst the sulphides are represented by samples of alabandine or manganese blende, and by a specimen of the rare mineral hauerite, from its only known locality, Kalinka in Hungary.

Mention has already been made at p. 78 of the value of certain oxides of manganese as sources of oxygen in the operations of bleaching and glass-making, for which purposes they are imported in large quantities.

The minerals of the somewhat rare metals which follow need but slender description. A few ores of bismuth are introduced, principally from the cobalt mines of Saxony; and with these are grouped samples of molybdenite from Bohemia, Greenland, and Chile : these are followed by some Saxon specimens of the uranium-ore called pitchblende, and by a sample of the peculiar Swedish mineral known as cerite, in which are associated the silicates of the rare metals, cerium, lanthanium, and didymium..

Tin

Case 20.—The tin ores of the continent scarcely come into competition with those of our own country, but large quantities of tin are imported from the isles of Banca and Billiton, and from the Malay peninsula. In the small group of foreign tin ores here intercalated, will be found some fine crystals of tin-stone from Brittany, and several specimens from the tin mines of the Erzgebirge Ore Mountains, which separate Saxony from Bohemia; and with these are placed samples from Spain, Russia, Greenland, Brazil, and the United States.

Following the tin ores are some specimens of the tungstate of iron and manganese, called wolfram, a mineral with which the ores of tin are commonly associated; and of the tungstate of lime named scheelite, after the Swedish chemist Scheele..

Cobalt and Nickel

Case 20.—The group of cobalt and nickel ores presents some interesting specimens, chiefly from the mines of Schneeberg in Saxony and Tunaberg in Sweden. The white cubic crystals of smaltine, with faces frequently curved and fractured; the pale yellow crystals of cobaltine, exhibiting compound forms allied to these of iron pyrites; and the pink crystalline or earthy erythrine, occurring frequently as an incrustation on other ores, are the most prominent among the cobalt minerals; whilst in the group of nickel ores attention may be directed to a small crystallized specimen of kupfernickel, some fine capillary crystals of millerite, a sample of breithauptite or antimonial nickel, and the fine emerald-green incrustations of carbonate of nickel from Pennsylvania : the composition of most of these minerals, and the applications of cobalt and nickel ores, have been noticed at p. 77..

Antimony

Case 20.—The fine series of antimony minerals commences with some specimens of the native metal, and of its oxides—valentinite and senarmontite. Of the principal antimony ore, called antimony glance. or stibnite, numerous specimens are exhibited from various localities; those from Hungary being remarkable for their fine crystalline forms; whilst the Borneo samples are interesting: as representing a very important locality. It will be observed that some of the specimens are invested with a yellow crust of oxide of antimony, whilst others are coated with the reddish oxysulphide called kermesite or antimony blende, of which mineral some specimens are exhibited from Bräunsdorf showing well the characteristic tufts of red hair-like crystals..

Zinc

Case 21.—On the top shelf of this case are -some fine examples of the exclusively American ores called zincite, or red oxide of zinc, and franklinite, a mineral in which the zinc oxide is associated with the oxides of iron and manganese, and which is valued as an ore of iron rather than of zinc. These are followed by a group of carbonates and silicates of zinc from the celebrated Vieille Montagne deposits. These mines, formerly called the Altenberg (old mountain), are situated upon part of the Belgian, Prussian, and neutral territories, between the towns of Aix-la-Chapelle and Verviers. The calamine of these deposits has been worked since 1435; but for four centuries it was employed merely as an earth to make brass, as it was not known to contain any metal. It will be remembered that a large mass of this calamine stands in the lower Hall (No. 45).

The group of zinc ores is brought to a close by several examples of blende, or sulphide of zinc, of which those from Hungary and Bohemia present fine crystalline forms, whilst other specimens are notable as containing silver..

Lead

Case 21.—A fuller description of the various minerals from which lead is extracted will be given in the notice of the British series (p. 100): the foreign specimens in the case before us are interesting for comparison with our own.

In the group of lead-spars attention should be directed to the fine transparent and well-formed crystals of anglesite, or sulphate of lead, and of cerussite, or carbonate of lead, from the Wheatley mine in Pennsylvania, where they occur in the upper part of rich lead veins coursing N.E. and S.W. in gneissose rocks; nor must we omit notice of the remarkably brilliant crystals of anglesite which bestud the cavities in the rich galena of Monte Poni, iu I he island of Sardinia. Of the phosphate of lead called pyromorphite are exhibited some examples of peculiar hollow crystals from the Wheatley mine, and of fine barrel-shaped crystals from the mines of Nassau.

A small group of the somewhat rare antimonio-sulphides of lead is here intercalated, including the species called boulangerite, pidgionite, and geocronite; and from these we pass to the most widely diffused ore of lead—its sulphide, called galena, of which mineral a large series of specimens is exhibited, fairly representing the principal lead-producing districts of the continent. France, Spain, Tuscany, Saxony, Hungary, and Russia have each contributed samples, and with these European specimens are placed a few samples from certain mines in Asia and America. The physical characters of this abundant mineral will, perhaps, be better studied among the more varied series from our home mines (see p. 100)..

Silver

Case 22.—Silver ores have been mined for from the earliest recorded periods of man's history.- Throughout Spain, France, and Britain it is quite clear that the Romans eagerly searched for this metal, as they have left behind them numerous remains of their mining and smelting operations. The silver mines of Spain were abandoned until within the last 30 years; within that period several rich mines of silver have been discovered. Tbo silver mines of Mexico have been much celebrated since the conquest of that country by Cortes in 1519.

The most productive silver mines in the world are those of South America,—New Spain, Peru, Mexico, and especially Potosi, as well as the names of some other places, have become almost synonymous with those used to signify precious metal. The greater part of the silver extracted by mining in Peru is found in a species of ore locally called pacos: it is a brown oxide of iron, with silver disseminated through its mass in exceedingly minute particles. The ore of Chile is similar, and one vein of it, existing in the Andes, is said to have been traced more than 90 miles, having branches running in the adjoining mountains, some of which are known to be 30 miles in length. This is regarded as the largest mineral vein in the world.

Among the most remarkable of the existing silver mines those of Real del Monte must be named. Those mines had been continuously worked since 1749; but long previously to that date extensive but irregular workings had been carried on. Silver mines of extraordinary value have recently been developed in the Nevada territory.

Among the silver minerals are some highly interesting specimens of the native metal, the fine solid masses from Chile being especially noteworthy. The remarkable association of this metal with native copper in the Lake Superior specimens has already been noticed (p. 82).

Combined with sulphur, either alone or associated with antimony or arsenic, silver forms a series of beautiful and valuable minerals.

Of these the ordinary sulphide called argentite, vitreous ore, or silver glance, is a soft and highly malleable mineral, assuming a series of nubic forms closely related to those of galena. Passing over the rare Saxon mineral miargyrite, we may notice among the antimonio-sulphides of silver the beautiful species called pyrargyrite, ruby blende, or dark red silver ore, of which the Mexican mines have contributed some magnificent hexagonal crystals; whilst from Saxony is exhibited a specimen of light red silver ore or proustite, mineral chemically differing from the last species in containing arsenic in the place of antimony. To the same class of minerals belong stephanite, or brittle silver ore, the rare species called fire-blende, and the mineral known as polybasite in which the silver is partially replaced by copper and the antimony by arsenic.

Another group of silver ores is formed by the combination of the metal with chlorine and its allied elements. The chlorides, bromides, and iodides of silver so formed, of which a few specimens are exhibited from the South American mines, are all affected to a greater or less extent by the action of light..

Gold

Case 23.—The collection of gold ores is headed by several specimens from Russia. In all probability the auriferous tracts of the Uralian mountains were worked over by the Scythians; and the Arimaspi of Herodotus, a people who had but one eye, and who took the gold away by violence from the Griffins, may have been, as Humboldt suggests, this nomadic people. Gmelin describes the ancient gold works which he discovered in the district; and Sir Roderick Murchison speaks of great piles of ancient drift or gravel which have been removed for the extraction of the gold.

Upon the character of the auriferous deposits of Russia Sir Roderick Murchison writes (Siluria, p. 443): In some spots in which the gold occurs is a heavy clay; in otheis, it is made up of fragments of quartz veins, chloritic and talcose schist, and greenstone, which lie upon the sides of the hillocks of eruptive rocks. It was from the infilling of one of the gravelly depressions between these elevations, south of Miask, that the largest lump of solid gold was found of which, at that time (1824), there was any record." This "pepita" weighs 96 pounds troy, and is still exhibited in the Museum of the Imperial School of Mines at St. Petersburg.

For remarks on the age of the gold deposits, and other interesting matters on this subject, the reader should consult "Siluria" by Sir R. I. Murchison, chapter xvii., "On the original formation of gold, and its subsequent distribution in debris over parts of the earth's surface."

The produce of the various gold-washing and amalgamation works of Russia appears to have been, for many years, about 1,500 poods; the Russian pood being equivalent to about 40 pounds troy, this will be equal to about 60,000 pounds troy. The following extract from the Anniversary Discourse of the President of the Geographical Society, Sir R. Murchison, in 1844, is to the point:—

"In Russia, as in the Brazils, the great mass of the metals is derived from local detritus or alluvia, usually called gold sand, but for which (as far as Russia is concerned) the term shingle would be much more appropriate. With very trifling exceptions, all such auriferous detritus in the Russian empire occur on the eastern side of the Ural. Slightly known, and near Ekaterinburg only, in the days of Pallas; it was not until the reigns of Paul and Alexander that these gold alluvia were found to extend in a certain zone to the north and south of that locality, throughout 5° or 6° of latitude, and that eventually gold was extracted from them to the annual value of about half a million sterling. Notwithstanding the increased exploration of late years, and many researches in the northern and southern portion of this chain, this quantity has been rarely exceeded; and latterly, the alluvia in some tracts being exhausted, it has begun to decrease. The reign of the Emperor Nicholas has, however, been distinguished by the important discovery, that portions of the great eastern regions of Siberia are highly auriferous, viz., in the governments of Tomsk and Yeniseik, where low ridges, similar to those on the eastern flank of the Ural, and, like them, trending from north to south_., appear as offsets from the great east and west chain of the Altai, which separates Siberia from China. And here it is curious to remark that, a very few years ago' this distant region did not afford a third part of the gold which the Ural produced; but, by recent researches, an augmentation so rapid and extraordinary has taken place, that in the last year (1843) the eastern Siberian tracts yielded considerably upwards of two millions and a quarter sterling, raising the total gold produce of the Russian empire to near three millions sterling."

A few specimens have been contributed from the American mines, and it will be remembered that a large mass of auriferous quartz from the Californian workings is placed in the hall (No. 103), and described at p. 39.

The long-worked gold mines of Hungary and Transylvania are represented by specimens from Schemnitz, Nagy-banya, and Vorospatak..

Platinum

Case 23.—The metal platinum was first discovered by Ulloa, a Spanish traveller in America, in the 1735. It has since been discovered in Columbia, St. Domingo, Borneo, in the sands of the Rhine, California, Canada East, and Russia.

"Though ores of platinum are found in the alluvia of the Ural chain in various parallels of latitude, it is only within the territories of the Demidoff family that they are still worked. After an examination of the greater number of the platinum works belonging to Nijny Tagilsk, all of which lie on the western slope of the Ural-tau in that parallel, M. G. Rose has shown that in one only of the numerous masses of alluvia was any gold mixed with it, and. that in no instance could he detect any veinstones of quartz, or other fragments of rocks, nor of magnetic iron ore, so abundant in the gold alluvia. The platinum had formerly, it appears, been found, for the most part, in fragments from the weight of a zolotnik to near one pound, though rarer examples had occurred of pieces weighing from three to upwards of eight pounds. According to Rose, the major part of the detritus associated with the platinum consists of serpentine, with very rare appearances of hypersthene or other materials, the ground over which it has been washed being either chlorite schist or quartzes° talc schist, the latter containing diffused epidote. The platiniferons alluvia on the west slope of the Ural ridge, like the gold alluvia on the east, have in truth been drifted into adjacent depressions from the culminating peaks of hornblende slate, serpentine, and greenstone, and are occasionally from 10 to 12 feet thick."—The Geology of Russia in Europe by Roderick Impey Murchison, & c. & c.

For the applications of platinum, see p. 121..

Tellurium

Case 23.—The few minerals which contain tellurium occur, in limited quantities, with the gold and antimony ores of Transylvania.

The native metal is now exceedingly rare, but half a century since it was found in rather large quantities in Transylvania, and was melted to extract the small quantity of gold which it contains.

In 1782 Muller and Reichenstein showed that the ores of tellurium contained a peculiar metal; Klaproth confirmed this. Sir H. Davy examined some of the oxides, but to Berzelius we are especially indebted for our knowledge of this metal..

Mercury

Case 23.—This metal is occasionally found native in small globules on cinnabar or in the fissures of the gangue, but the native metal usually contains a small proportion of silver, the amount of which sometimes rises to a considerable extent, forming the speeies called amalgam. Most of the quicksilver of commerce is, however, obtained from the sulphide known as cinnabar or native vermilion. In Europe the most important mines are those of Idria, in Carniola; and Almaden, near Cordova, in Spain; whilst in California valuable deposits of this ore occur at New Almaden. The metallurgical treatment of cinnabar will be noticed at p. 111..

Arsenic

Case 23.—The collection of foreign ores is brought to a close by a few arsenical minerals. Of these the principal are the bright aurora-red bisulphide of arsenic called realgair, and the lemon-yellow tersulphide known as orpiment, of which the former is the more important. With these is placed a cup beautifully carved in native realgar by the Chinese, who highly esteem the mineral for its powerful medicinal properties. Both the arsenical sulphide, have long been employed as pigments, but for this purpose they are usually prepared artificially..

Specimens to illustrate the phenomena of lodes or mineral veins

Wall-cases 24 to 36.

In the cases forming the circular or north end of this floor is arranged an instructive series of specimens intended to exhibit, within such a space as might be conveniently studied, many of the conditions under which lodes or mineral veins occur, and the general characters which they present. For the purpose of aiding those who may not be familiar with the phenomena of mineral formations, the following popular description of the more important circumstances connected with those accumulations is written, referring for a more detailed notice to the remarks of Mr. Smyth in the Mineral Catalogue (p. 88 et seq.)

It may, indeed it does, appear to many who are familiar with our mineral districts that the utmost uncertainty prevails in everything associated with the processes of mining. "Where it is, there it is," is a bye-word among many practical miners, who mean by it to express their ignorance of any general laws by which we may be guided in search of metalliferous treasures. Admitting that our knowledge is insufficient to enable any one to determine whether there exist metallic ores at a considerable depth beneath our feet, in the earth's crust, by mere observation of the surface, and that, consequently, mining explorations must be to a great degree speculative—it is yet certain that those mineral formations are distributed in obedience to some exact laws, and that, like all natural laws, the discovery of them is within the reach of the human mind. Observation, experiment, and thought will,- no doubt, sooner or later advance man- to a knowledge of the conditions upon which the accumulation of metalliferous minerals depends. In the meantime it is important, by the study of such collections as these, that every student should familiarize himself with the physical phenomena exhibited by the deposits within-mineral lodes, and learn the conditions which prevail in any of those districts where subter-.ranean explorations .are carrried on..

Model of a portion of a Mining District in Cornwall. Central Series. .No. 32.

By reference to this model, near case 24, the character of mineral lodes will be understood. The two dissimilar woods are intended to illustrate the prevailing rocks—granite and killas Or clay slate—of that importaiat mining county, Cornwall. The lines which run across these rocks are supposed to represent mineral lodes, containing either tin or copper, as shown by the different colours introduced. Any one imagining this model to represent some square miles of country, .across which there has occurred extensive cracks-, either in the process of the consolidation of the rocks, or by mechanical force since the period of consolidation, will realize the facts, in the main, of our mineral lode formations. Cracks have been formed, no matter how, in the rocks they traverse, and these fissures have been -channels through which water passed to considerable depths into the crust of the earth. In the process of tithe those fissures were filled with earthy or metallic minerals, and probably under the influence of the immeasurable force of the crystallization of such masses, not only were the first fissures enlarged, but lateral ones formed, which would eventually partake of the general character of the main fissure or lode. By the study of the model of the lead mine at Nentsberry Greens, .Alston, Moor, No.30, opposite case 20, in the county. of Cumberland, it will- be seen that even in a stratified country the mineral lodes may, in like manner, be regarded as cracks extending from the surface to an unknown depth through the different strata.

The common hypothesis formerly adopted was, that the veins were filled with matter introduced from below, which either was injected in a state of igneous fusion, or ascended by sublimation; but this view is generally abandoned, very few of the-facts observed appearing in any way to support it.

By some experimentalists, who have succeeded in producing artificially, by the agency of electricity, miniature mineral lodes, those valuable natural formations have been referred to electrical power. We must not, however, too hastily decide upon this,—the probability being that a set of physical forces, which are as yet only dimly seen by the eye of science, acting on the material particles will be found to be the causes regulating the effects under consideration.

It is certain that in Devon and Cornwall there are distinct indications of the influences exerted by two dissimilar rocks in producing the formation of the metalliferous minerals. It is evident too, that a main line of direction is observed by mineral lodes, and usually the direction of lodes containing the ores of lead is nearly at right angles to that of the copper and tin veins in the same district, the latter coursing nearly east and west, whilst the "cross courses" and lead veins run almost north and south. Again, in the lead districts of Wales and of the North of England, we find the ores of this metal commonly occurring in the limestone bands, and appearing only slightly, if at all, in the sandstone and shale strata associated with the limestone. There are, however, districts, and extensive ones, in which the lead occurs in the sandstone and not in the limestone, and there are some in which the preference appears to have been given to the shales. This is strikingly shown at the Grassington and at the Cononley mines. Such facts prove to us that some conditions beyond those which are dependent upon the chemical constitution of the rocks are to be sought. Indeed, the whole subject is open for investigation, and a rich harvest awaits the student of nature who may, zealously and thoughtfully, cultivate this extensive and important line of research.

Prepared by these general preliminary remarks to understand the aim of the collection, we may at once proceed to its systematic examination. The series commences in case 24 with a number of specimens illustrating the formation of veins on a small scale in nodular concretions of clay-ironstone, by the contraction which the nodules have suffered during consolidation, and the subsequent deposition of various minerals in these fissures of contraction. Not only do carbonate of lime, quartz, hatchettine, and other nonmetallic minerals occur in such cracks, but associated with these are found various metalliferous minerals indentical with those which form the object of exploration in metallic veins; such, for instance, as zinc blende, galena, and copper pyrites. The remainder of this case is occupied by samples of narrow simple veins known from their small breadth as "strings" or "threads". Some of these branches consist of metallic mineral, others of non-metallic; and ,some interesting specimens are introduced to show the differences observable in the character of a vein in passing from one rock to another.

The series of simple veins is continued in the succeeding cases (Nos. 25 and 26), the veins, however, increasing in width or becoming more powerful. In: many specimens introduced into this part of the series it will be observed that the minerals instead of being gathered into strings are distributed through the rocks themselves in an irregular manner; this is especially the case with tin-stone, which frequently occurs disseminated through granitic rocks. It has been suggested that in many cases the metalliferous mineral has been segregated or separated from the surrounding rocks, and accumulated in the form of veins, the particles of a like character being drawn into these lines of accumulation by some of those mysterious molecular forces which are but little understood.

From the simple veins which, with few exceptions, have consisted of a single mineral only, we pass in the next cases (27 and 28) to illustrations of lodes, consisting, first of two minerals, and then of several. These instructive examples are of high practical value, as illustrating the subject of the "paragenesis" of minerals, or the characteristic association of certain species,—a question of the deepest interest alike to the mineralogist, the geologist, and the miner.

In some instances the formation of the different minerals has been contemporaneous, as in the fine example from the Ecton mines (No. 194), in which cale-spar and copper pyrites have simultaneously crystallized; but in other cases the minerals have obviously been formed in succession, as seen in the fine Brazilian veinstone (No. 203a), where we observe a sequence of quartz, dolomite, and magnetic pyrites. The association, however, is in these cases, to a certain extent, irregular, and it remains for us to study in case 29 those specimens in which may be traced a definite succession of regular deposits. This is strikingly illustrated by the beautiful specimens of "riband" or "banded" veinstone from Saxony (Nos. 232 and 233), in which we notice, within a very limited width, a succession of alternate deposits of quartz, galena, heavy spar, iron pyrites, and zinc blende, the layers being repeated with tolerable symmetry on each side of the veinstone. Among the instructive specimens in this case may be noticed the fine Bohemian veinstone (No. 252), which conveys an excellent idea of the general characters of a lode; but it is to be regretted that space does not admit of its being placed in its natural position.

Some interesting specimens in the following case (30) exhibit certain peculiarities in the succession of the deposits. In many of the examples crystals of a later-formed mineral have been deposited on particular sides only of the pre-existing mineral, the cause determining this elective action being in many cases far from obvious.

Vein deposits after their formation have often been subjected to the action of certain dislocating forces, which have again established fractures, and in these new fissures other minerals have been deposited, thus producing the structure called "comby." Several examples of comby lodes are introduced, in which the succession of plates shows that the opening must have been several times repeated at distinct intervals.

The mineral deposited in a lode occasionally serves to cement together angular fragments of the neighbouring rocks, and even of other veins. In case 31 is a large collection of such "brecciated" lodes, in which a non-metallic mineral has acted as the cement, fragments of sandstone, for instance, being cemented by heavy spar; whilst case 32 is devoted to the exhibition of those in which a metalliferous mineral has been introduced as cement, as when sandstone fragments are bound together by galena. In the upper part of case 33 are some interesting breccias containing fragments of pre-existing lodes, pieces of copper pyrites, for instance, being embedded with fragments of quartz in a "flucan" or clay.

The fine pendent forms of the stalactites, introduced in case 33, will naturally attract attention, and it will be observed that many of the Cornish specimens exhibit a regular sequence of deposits, the stalactite having been coated by a succession of newer-deposited minerals.

The polished and striated surfaces of the "slickensides," in case 34, evidently point to some sliding or grinding motion in the mass constituting the lode, affording evidence of movement since the formation of the metalliferous matter, such as would be sufficient to account for the fissures and breccias to which allusion has been made.

From these evidences of mechanical disturbance in mineral lodes, we may pass to those changes of a chemical character which vein deposits frequently suffer, as especially attested by the phenomena of "pseudomorphism" (p. 76). In this case is arranged a large collection of the so-called "displacement" pseudomorphs, or those in which one mineral is deposited, either upon or in the place of another. Of such changes the curious "boxes" from Virtuous Lady Mine, near Tavistock, are interesting examples. A coating of carbonate of iron has been deposited upon cubic crystals, probably of fluor-spar, and by the subsequent removal of these crystals the encrusting carbonate has been left in the form of large hollow (Tubes, in which quartz and copper pyrites have finally crystallized.

It may thus be readily understood how a cellular character may be imparted to a lode by the hollows formed on the removal of the original minerals.

The formation of certain pseudomorphs by the very gradual substitution of one mineral for another has been explained in connexion with the interesting crystals of tin-stone in the form of felspar (p. 76).

In addition to the displacement and substitution pseudomorphs just noticed, there is yet a third group in which the change of mineral is readily explicable by chemical action, and of these "alteration" pseudomorphs a series is exhibited in the succeeding case (35). These may result either from the addition or removal of a constituent, or from a partial exchange of ingredients. Thus the crystal of calamine in the form of a large scalenohedron of calcite has been formed by the exchange of lime for oxide of zinc. So obvious in many cases is the formation of these "epigenic" pseudomorphs that it may, to a certain extent, be successfully imitated, and an interesting series of such artificial pseudomorphs, prepared by Mr. H. C. Sorby, F.R.S. is placed on the model of the steel works at the northern end of the room. In nature, such chemical action occurs in many cases on a very extended scale, affecting mineral masses often of enormous extent. To illustrate these changes there is introduced into this case a large series of minerals occurring mostly in the upper parts of lodes, where the original deposits have been subjected to atmospheric influences. Thus the crystals of anglesite often found in the shallow workings of a lead vein are true products of alteration, having resulted from the absorption of oxygen by the galena forming the body of the lode, and the consequent oxidation of the sulphide of lead to a sulphate. A very common alteration in mineral veins is illustrated by No. 538, in which large pentagonal dodecahedrons of iron pyrites are super. facially converted into brown iron ore, by the elimination of sulphur and the addition of oxygen and water.. On the "back" or outcrop, of a lode such a change is exceedingly common, the superficial deposit of loose brown Iron ore, which thus acts as a cap to the ore beneath, passing under the name of "gossan." The greater part of the following case (36) is devoted to the display of varied samples of this gossan, which, although not perhaps very attractive to the eye, are nevertheless of the highest importance to the miner, who is frequently enabled to judge from them of the probability of cutting ore in the deeper workings.

The remaining portion of this case (30) is occupied by a collection of specimens illustrating a class of chemical changes, of a different character from those already studied. In these specimens the decomposition of certain metallic minerals has resulted in the production of native metals : thus there will be found among the specimens, crystals having the characteristic octohedral form of red oxide .of copper, but consisting entirely of the native metal.; the copper having been reduced from its combination with oxygen; and it is indeed probable that many of the metals which now occur in a native state have been reduced by successive stages from various combinations, often of considerable complexity..

Colonial productions

Wall-cases 37 to 42 on E. side.

Australia

Case 37.—The gold fields of Victoria, which naturally claim priority in any notice of the mineral products of Australia, are represented by a number of specimens which from their interest are separated from the general collection, and grouped together in a special case on the western side of the room, which will be noticed in the description of the central series (see p. 124). Second only in interest to these gold fields are the remarkable copper deposits in the neighbouring colony of South Australia, well illustrated by the specimens in the case before us. The are principally from the famous mines of Burra Burra, situated about 90 miles N.E. of Adelaide. The rich deposits of carbonate of copper in the earlier workings at these mines resemble in many respectis the malachite formations of Russia, already described. In a great basin, formed in an amphitheatre of hills, is an immense deposit of clay, resulting from the, decomposition of the clay slate of which the surrounding hills are formed. In this clay the remarkable deposit of copper ore is found. There are some evidences which appear to show that the earliest-condition of the mass was that of oxide and native copper; this, from the continued action of carbonic acid, contained in all probability in the water, was converted into, a carbonate.

There are no appearances of any mineral lode of the character which occurs in our own copper mines. The veins, said to be met with, are merely extensions of the mass by infiltration through the clay.

The Burra Burra mines were started on the 5th September 1845, with a capital of 12,520l., subscribed by a few merchants and traders at Adelaide, In spite of the rudeness of the early workings, their distance from the shipping port, and the disadvantage, of unmade roads, these remarkable mines nevertheless yielded during the first five years a profit of nearly half a million. sterling; certainly one of the most successful mining adventures. upon record. When, in 1851, the gold fever set in, these important, mines were deserted by the working miners; but when men. had begun to discover that the profits which are obtained from the exciting but uncertain search for gold are not commensurate, with the risks run and the labour expended, they returned to more. stable sources of employment, and. in the early part of 1855 the workings at Burra Burra were resumed, and are still in active operation.

In Case 19, on the western side of this floor, are some fine specimens of the red oxide and blue and green carbonates from the same mines; and in the lower hall is another large mass of the ore (No. 31). There will also be found in the hall a fine sample of the ore (No. 164) from the workings of the Great Northern Mining Company of South Australia, commenced in June 1860, in the district north of Port Augusta, at the head of Spencer's Gulf.

Case 38.—The South Australian copper ores are continued in the upper part of this ease. Samples of copper glance and other rich ores are exhibited from the Kapunda mines, which have been successfully worked since 1844; whilst other specimens have been contributed by the mines of Mount Barker, Reedy Creek, Kanmantoo, and New Cornwall, the last named being situate in the neighbourhood of the brilliantly successful workings at Wallaroo, on Yorke peninsula.

Passing over the lead, iron, and antimony ores, which are at present only of inferior importance to the colony, we meet with a number of samples of tin ore.

The black sand, as it was commonly called, did not for some time attract attention, except for the gold which it contained. Eventually, however, it was found to contain tin; some samples were sent to England and determined to be of considerable value, and now, in all probability, an important trade in Australian tin will be established. In 1865 we imported from Victoria 222 tons of tin ore.

The few specimens of Australian coal will be regarded with much interest, for the carboniferous formations of Australia have yet to be developed..

New Zealand

Case 37.—Of the few minerals exhibited from the Northern Island, perhaps the most interesting is the fine magnetic iron sand, which occurs in deposits of vast extent along the shore of New Plymouth, at the base of the trachytic cone of Mount Egmont, in Taranaki. The excellent quality of the steel prepared from this sand is supposed to be referable to the large proportion of titanium present, an analysis of the ore yielding 88.45 per cent. of oxide of iron, and 11.43 of oxide of titanium.

There will, also be found a specimen of copper ore from the lower palæozoic of Kawau, near Auckland; and some samples of New Zealand tertiary coal obtained from Waikato, distant from Auckland 35 miles, and 10 miles from Manukau harbour. Coal is also obtained at Matakana, 15 miles north of Auckland..

East Indies

Case 37.—An interesting and extensive series illustrating the varieties of corundum stands at the head of the Indian minerals. The name corundum is applied to the opaque, roughly crystallized varieties of native alumina, whilst the massive and more impure forms of the same species are known as emery; the passage of corundum into emery is illustrated in this series. From its hardness, which is inferior only to that of the diamond, the mineral in its coarser forms is extensively used for grinding and polishing purposes (p. 33). As these varieties of alumina will again be brought under notice in describing the contents of the horse-shoe case, we may pass, without further remarks, from this series to the iron ores of India, which will naturally attract much attention. The lower part of this case is devoted to metallurgical illustrations, but the ores from which the metal is reduced are principally shown in the following case.

Case 38.—The celebrated "wootz," or Indian steel, is manufactured by the natives, chiefly from the magnetic ores, of which many samples are here exhibited. The method employed for smelting this ore is very rude. Layers of small pieces are disposed alternately with others of charcoal in an open furnace, and exposed to the blast of two small bellows made of goat-skins. The metal when reduced falls into a hole at the bottom of the furnace in the state of malleable iron. To convert this into wootz steel, a small wedge is cut from the iron cake, and placed with pieces of dry wood in a clay crucible, which is heated in a rude furnace until the iron becomes carbonized, and on breaking open the crucible the steel is found at the bottom in the form of the small conical cakes here exhibited.

The iron manufacture has been carried on somewhat extensively in the Daraoodah valley and Beerbhoom. "At Dyoucha," says Professor Oldham, "there are at present about 30 furnaces at work for the reduction of the ore into pig iron, or what is here called cutcha iron, and about as many more for refining it, or making it pucka; the two operations being carried on by totally different sets of people, and, what is curious, by people of different religions, those who reduce the ore in the first instance being invariably Mussulmen, and the refiners as invariably Hindoos.

"From each of these furnaces when at work between 20 and 25 maunds of pig iron will be turned out during a week. The furnaces work throughout the year, with only occasional stoppages for poojahs; that is, provided the proprietor has been able to lay in a stock of ore and charcoal previously to the rains commencing, sufficient to last till the weather again admits of the miners obtaining the ore. From each furnace, therefore, a produce of pig iron of about 1,100 maunds, or nearly 35 tons, is annually obtained."

At Dyoucha are 30 furnaces, at Narainpore about the same number, at Damrah four, and at Goanpore six, or in all about 70 furnaces, producing nearly 2,380 tons of pig iron every year. In refining nearly one-fourth of its weight is lost, 10 maunds of the cutcha iron yielding about 7 maunds 10 seers of the pucka iron. This will give the entire produce of the whole district at about 1,700 tons of refined iron. Oldham's Report on the Damoodah Valley, 1852.

A few samples of copper and antimony ores are introduced. It is known that the Himalayan mountains contain copper and lead, but the mines have only been worked superficially, and it is doubtful whether they would repay the great cost which must be incurred. In several other districts, Ulwar and Beerbhoom, Bellary, Dhunniara, Tennasserim, and Nepal, copper ores are found.

A rather extensive series of useful non-metallic minerals is exhibited from the Madras Presidency. These embrace several varieties of kaolin or china-clay, valuable in pottery manufacture (p. 49); and a collection of variously-coloured ochres, which, both in a native and a burnt state, are available as pigments.

Case 40.—The non-metallic minerals of India are continued in this case, the upper shelves being occupied by some fine specimens of zeolitic minerals from the tunnels cut through the trap-rocks of the Bhore Ghaut during the construction of the great incline which ascends the Syadrahee range on the line between Bombay and Poonah.

Among the minerals on the following shelf, the specimen of kunkur is notable as a representative of the vast deposits of this siliceous variety of carbonate of lime, which occurs in singular concretionary forms, and is largely burnt in India for lime.

The specimens of tin ore from the Malayan peninsula, and from the isle of Banca to the south of it, are interesting from their commercial importance. From these, and other adjacent localities, tin has long been obtained, and Humboldt was of opinion that the Phœnicians, by means of their factories in the Persian Gulf, maintained a trade in tin with India; and as the word Kassiteros is the ancient Sanscrit word Kastira, he is disposed to regard the islands of the Eastern Archipelago as one set of islands, to which the term Cassiterides, or "land of tin," was applied.

Tin from our other eastern possessions: comes to us through Singapore; but this is mixed up with much which is produced in the Dutch East Indian possessions; in 1865 we received from British India 4,932 tons, and from Holland 510 tons of tin..

British America

Case 40.—The mineral wealth of Canada, with which the labours of the Geological Survey have made us acquainted, is very fairly represented through the courtesy of Sir William Logan, the Director. Although some of the specimens, on account of their size, are necessarily placed in the following cases, it will be convenient to describe in this place the whole of the Canadian series.

As especially interesting among the non-metallic minerals may be noticed the apatite or phosphate of lime, which occurs in considerable deposits in the Laurentian limestones, and is highly valued by the agriculturist as a useful fertilizer. The plates of Canadian mica, which are found of extraordinary size and thickness, have been employed in certain situations as a substitute for the more easily injured glass; and the graphite, or black-lead, has also been worked, although occurring only in irregular deposits of no very considerable extent.

Whilst the limestones are notable for furnishing these minerals, the granitic and gneissose rocks deserve mention for the fine specimens of felspar which they yield. The peculiar soda-felspar called peristerite is remarkable for its beautiful bluish opalescence, whilst the variety of potash-felspar known as perthite is attractive by its peculiar banded structure and aventurine-like reflections. (See polished specimen in Horse-shoe case, No. 1,068).

A sample of coralline limestone from Enniskillen is interesting as the rock from which probably arises the Canadian petroleum, or rock-oil; the wells in this locality being carried through a considerable thickness of palmozoic shales overlying this corniferous limestone.

Passing to the metallic minerals, we may notice from the Bruce mines, on the shores of Lake Huron, the fine samples of the copper ore, which occurs it rich veins traversing the Huronian rocks, or those which immediately overlie the Laurentian series. Considerable interest attaches to the Canadian iron ores, the bog ore having a very wide superficial distribution, and the richer magnetic ore occurring in beds of prodigious extent. The titaniferous iron, from its occurrence in large quantity, promises to become of considerable importance, whilst certain varieties of iron pyrites appear to contain an amount of cobalt sufficient to render profitable the extraction of this somewhat rare metal. From Eastern Canada are obtained the chrome iron ores, which, as usual, are associated with serpentine rocks. For further information on this series consult the "Reports of the Geological Survey of Canada."

Case 41.—The specimens in this case which will doubtless be regarded with most interest are those illustrating the gold discoveries which have been made in British America during the last few years. From Nova Scotia are exhibited samples of the so-called "barrel-quartz" of Laidlaw. Occurring beneath only a few feet of quartzose rock, it forms an extensive horizontal bed, presenting a remarkable succession of folds or contortions; probably the result of lateral compression. The undulating surface of the deposit, which has suggested the local name, is well seen in the water-colour sketch in the upper part of the case, where the barrel-quartz is exposed by removal of the superficial rock.

A prominent position in the case before us is necessarily given to the collection illustrating the extensive gold districts of British Columbia. It appears that so early as 1852 small quantities of gold were found in Queen Charlotte Island, and the metal was afterwards discovered on the mainland, in the Frazer River valley, and in various parts of the Cascade range. The first official report of these discoveries, which was received in 1856 from the Governor of Vancouver Island, failed to excite any considerable attention; but the extent of the deposits and the success of the operations which were in progress being confirmed by subsequent reports, public attention was at length aroused, and in 1858 vast numbers of emigrants flocked to the new colony.

The great centre of the most successful workings was the rich auriferous district situated some distance inland, and known (from being a favourite haunt of the reindeer or caribœuf) as the Cariboo country. The beds of the Frazer River and its numerous tributaries were also highly productive, and the alluvial terraces which border many of the streams yielded much gold to the "bench diggers." More to the south, on the eastern side of the Cascade range, gold has been worked in the Similkameen, the Okanagan, and other streams which are direct or indirect tributaries to the Columbia River.

After a period of successful operations, in some cases of the most brilliant character, the workings gradually became less productive, and were for the most part abandoned; the washings at present being carried on only to a very limited extent, principally by Chinamen.

The West Indies are represented by a small number of specimens, chiefly from Jamaica. The existence of copper ores and other minerals in this island has long been known, but the explorations which have hitherto been made have not been sufficiently extensive to decide whether the metalliferous mineral exists in sufficient quantities to warrant a large outlay of capital..

South Africa

Case 42.—If the copper ores just noticed are only of meagre interest, it is certainly far otherwise with those in the collection before us. The copper ores of Namaqualand, which merit considerable attention, are very fairly represented by a tolerably numerous series, contributed by Mr. Wyley. The ores occur in veins traversing highly contorted granitic and gneissose rocks, and presenting a considerable variety of copper-bearing minerals. In the upper part of the deposits, where surface-action has been most active, the copper ore is chiefly in the form of silicate and oxide, but these are commonly followed at a greater depth by purple ore, and this again by copper pyrites. Considerable quantities of iron ore occur with these copper minerals, and a little molybdenite is occasionally present.

In the upper part of the case are some Indian spears from South Africa, made from the native carbonate of iron, reduced by cow dung.

Raving completed our survey of the Colonial products, we return to the British ores which remain to be noticed. These are the lead and iron minerals which occupy the succeeding cases..

British ores

2nd Division. EASTERN SIDE. Wall-cases 43 to 56.

Lead

Cases 43, 44, 45.—Lead mining has been carried on in this country from a very early period. When in the possession of the Romans, many of the lead mines in Wales and England were worked, and considerable quantities of lead obtained, as we may infer from the immense accumulation of slags in Derbyshire, the Mendip_. hills, and elsewhere. There does not appear to have been any period in our history during which mining for lead was not followed to some extent; but in the reigns of Henry the 8th and of Queen Elizabeth, especially in the latter reign, a fresh impetus was given to British mining by the introduction of a number of German miners. That mining for lead must, previously to this, have been extensively carried out is proved by the circumstance that Edward the Black Prince took several hundreds of the Derbyshire miners into Devonshire, and it is said that the result of his mining speculations in the west was the realization of wealth sufficient to defray the expenses of his French wars. Many curious laws were made for, and special privileges were granted to, particular mining districts, as the King's Field in Derbyshire, and the Myne-deeps,—as the Mendips were formerly called.

The Dish of Lead.—Among the curious customs of Derbyshire in the King's Field was this :—The ore was obliged to be measured in the presence of the barmaster before it was removed from the mine, for which purpose, in Wirksworth wapentake, a rectangular box was used, 28 inches long, 6 wide, and 4 deep, and reputed to hold 14 Winchester pints when level full. In measuring the ore every 25th dish is set aside by the barmaster as the King's cope or lot. An old dish of this kind stands on the model of the water-wheels, No. 35, near this case, and bears the following engraved inscription :—

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It appears now usual for the Derbyshire smelters to consider 58 lbs. as the standard weight of a 14 pints dish of ore.

The principal lead-producing counties of England are Durham, Northumberland, Cumberland, Yorkshire, Derbyshire, Shropshire, Devonshire, and Cornwall; in Wales, Cardiganshire, Flintshire, Montgomeryshire, and Denbighshire. Lead is also obtained from four different counties in Scotland, from eight in Ireland, and it Is raised in large quantities in the Isle of Man. Ores from nearly all those districts will be found in these cases.

The most important ore of lead is the widely diffused sulphide called galena. In addition to the lead, of which the purer varieties of galena contain upwards of 86 per cent., various other metals are usually present in greater or less quantity. Of these, silver is the most important, and it is indeed highly probable that neither silver nor gold is ever entirely absent from galena. The former is extensively extracted by a process which will be subsequently described (see p. 110).

Following the specimens of galena are samples of other lead ores, less widely diffused than the sulphide, but many of them, nevertheless, of considerable importance. Foremost among these stands the carbonate of lead, called cerassite or white lead ore. This mineral sometimes occurs in acicular or needle-shaped crystals, of which a magnificent specimen from Devonshire will be found in the central case No. 23; but more frequently it is found in an earthy form often investing galena, from whose decomposition it results. Among the oxidized lead ores will also be found some brilliant rhombic crystals of anglesite or sulphate of lead, and of the fine blue mineral called linarite, a sulphate of lead coloured by copper. The phosphate of lead termed pyromorphite, and known to our miners as "green linnets," is a mineral in which the phosphoric acid is frequently replaced to a greater or less extent by arsenic acid, thus passing into the species called mimetite. In these minerals the phosphate and arseniate of lead are associated with plumbic chloride.

The rare vanadate of lead already noticed as vanadinite is related by form and composition to the phosphates and arseniates of lead, and these again to the phosphate of lime called apatite..

Iron

Case 46.—Iron pyrites, although containing nearly one-half its weight in metal, cannot, in consequence of the sulphuretted condition of the iron, be rendered available as a metallic ore; it, nevertheless, possesses a certain commercial value as a source of sulphur, and from its employment for this purpose the pyrites is commonly known as "sulphur ore." In Cornwall, where it is by no means an uncommon constituent of copper veins, it passes under the name of "mundic," whilst the coal miner, who constantly meets with impure varieties, recognizes them as "brasses."

The name pyrites is derived from the Greek νρέτης, purites), because, as Pliny says, "there was much fire in it." Heaps of pyrites undergoing decomposition by the action of the atmosphere develope a large quantity of heat, in some instances sufficient to set the mass on fire.

Iron pyrites is essentially abisulphide of iron, and is therefore identical in chemical composition with marcasite, a mineral which, however crystallizes in totally distinct forms; ordinary pyrites appearing in cubes, octohedrons, or certain hemihedral forms derived indirectly from the cube, whilst marcasite occurs in a series of prismatic forms, which have suggested the name of rhombic pyrites. It frequently appears in irregularly shaped nodules common in the chalk, and the crystals are often aggregated into groups, forming the variety called "cockscomb pyrites."

The arsenical pyrites or mispickel has already been noticed as a source of arsenic (p. 81), and the bronze-coloured magnetic pyrites or pyrrhotine has been mentioned in the description of the foreign ores.

Vivianite, childrenite, and pharmacosiderite are minerals which will be found in this case, but being of somewhat rare occurrence they merit no special description.

Case 47.—The value of magnetic iron ore in Sweden, Russia, India, &c., for the production of a very superior quality of steel has already been noticed. In this country, however, the ore is comparatively unimportant, occurring only in very limited quantity. The peculiar pisolitic ore from Rosedale in Yorkshire is interesting from its occurrence in the lias as a deposit of considerable extent.

Case 48.—As the most important of the numerous localities in which the valuable hæmatite or red iron ore is found in this country, may be mentioned Ulverstone in North Lancashire, and Whitehaven in West Cumberland. The crystallized variety called specular ore or iron glance is represented by some specimens from the Cleator Moor deposits, where it occurs in cavities in the compact ore. The delicate scaly or lamellar crystals from Devon and Anglesey show the characters of the foliated variety of specular iron called micaceous iron ore; whilst the fine reniform and mammillated samples of compact haematite from Cumberland and Lancashire exhibit well the characteristic forms which have suggested for these varieties the popular designation of "kidney ore". On account of the red colour of the powder the name hæmatite, from αἷμα (haima) blood, is applied to this species.

Case 42.—A mineral so abundant and so widely diffused as limonite or brown iron ore naturally requires an extensive series for its illustration. Among the numerous localities represented in the case before us, the Forest of Dean may be cited as a district in which the brown ores have long been raised. The botryoidal and stalactitic forms, sometimes called brown hæmatite; the fibrous varieties, termed from their structure wood iron ore; and the friable earthy forms known as yellow and brown ochres, are so many varieties of this same species. The composition of these varieties is subject to variation within certain limits; but a crystallized hydrous peroxide of iron of definite composition is occasionally met with, and has been separated as a distinct species under the name of gOthite. The magnificent specimens of gothite from Restor-mel, near Lostwithiel, in Cornwall, are in every way worthy of notice.

The brown iron ores of the secondary strata, especially those of the lias and the overlying oolites, have acquired considerable importance within the last few years. Samples of these will be found in the lower part of this case. The celebrated Cleveland ironstone was discovered in 1848–9, on the north-eastern coast of Yorkshire. "From Redcar to Middlesbro'-on-Tees there crops out a solid stratum of no less than 15 feet thick. This remarkable ironstone seam extends over a region of some hundreds of square miles. It is capped by sandy shales, containing scattered nodules of ironstone, and ultimately, above the marlstone series to which it belongs, by the upper lias shale, so well known along the Whitby coast for its fossils, jet, and the application of some of the beds to the manufacture of alum."—(W. W. Smyth.) The main body of the Cleveland ore is a carbonate of the protoxide of iron, but the upper part of the deposit passes into brown ore.

In Northamptonshire and Lincolnshire, ironstones are now extensively worked and smelted. The Northamptonshire ironstone occurs in the Northampton Sand at the base of the Great Oolite; while the Lincolnshire ironstone—like the Cleveland ore—is found in the Marlstone or Middle Lias. A lias ironstone is also worked at Fawley in. Oxfordshire, and an oolitic ore at Westbury in Wiltshire.

Case 50, &c.—The characters of the pure carbonate of iron have been noticed in the description of the foreign ores (p. 84). In the case before us, in addition to the rhombohedral and lenticular crystals from Cornwall, are specimens of spathose ore from the valuable deposits of the Brendon Hills in Somersetshire, and of Weardale in Durham.

Spathose iron ore is a mineral whose composition is subject to considerable variation, the carbonates of lime, magnesia, and protoxide of manganese frequently replacing to a greater or less extent the carbonate of iron. Moreover this carbonate of iron is frequently associated with certain argillaceous impurities which interfere with its crystallization, and give rise to the dark-coloured massive varieties called clay-ironstones. These impure argillaceous carbonates,—which are so profusely distributed throughout our coal-measures, partly as regular seams of variable thickness, and partly as nodular concretions,—constitute the ore which, in this country, yields by far the largest amount of our iron—a fact by itself a sufficient apology for the rather large amount of space devoted to the display of these ores, confessedly somewhat unattractive in appearance. But the exhibition of a complete series is the more desirable in an institution of a practical character, since the ores, possessing neither crystalline form nor definite chemical composition, are not entitled to take rank as true mineralogical species, and would therefore find no place in a purely scientific collection.

The extensive series of clay ironstones commences with a number of specimens illustrating the characters of the nodular forms, and the minerals which these nodules frequently contain. The lower part of the present case and the whole of the six following cases are occupied by the systematic collection of ironstones, arranged geographically in the following order :— South Wales, North Wales, Shropshire, South Staffordshire, Warwickshire, North Staffordshire, Yorkshire, Derbyshire, and the Northern Counties.

Intercalated with these argillaceous carbonates of iron are a few samples of the carbonaceous ironstone, well known as black hand. From this ore, which was discovered in 1801 by Mr. Mushet, and is hence frequently called Musket stone, the largest quantity of the Scotch iron has been for many years made.

Information on the series of ironstones will be found in the "Mineral Catalogue," and further details in the Memoirs of the Geological Survey on the "Iron Ores of Great Britain;" whilst the best idea of the value of our iron manufacture will be gained by consulting the "Mineral Statistics."

The Metallurgical Collections

In the recesses on each side of the room at the southern or Jermyn Street end stand six flat cases devoted exclusively to the illustration of metallurgical operations. These cases are placed, as far as convenient, in front of the wall-cases containing the corresponding ores whose metallurgical treatment is here illustrated; the series of iron-smelting products, for example, being arranged immediately in front of the British iron ores. The processes illustrated in these cases, although for the most part British, are by no means exclusively so; specimens from foreign works being, in many instances, placed side by side with our own productions.

Metallurgical operations, presenting, as they frequently do, considerable complexity in their details, could not possibly be described in a popular guide with anything like scientific precision; but in order that the collection may not be entirely barren of interest to the general visitor, it seems desirable to introduce a brief sketch of the main features of each process, referring for detailed information to any modern work on the subject, especially to Dr. Percy's "Metallurgy;" to "Manufactures in metal," revised by the author of this Guide in Lardner's "Cabinet Cyclopedia;" or to "Phillips' Manual of Metallurgy."

Copper smelting

Table-case 16.—The ore when raised from the mine may be more or less pure, it may be mixed with other metallic minerals or with earthy ones; it has therefore, as a first operation, to be freed as much as possible from those. The processes employed are termed "dressing." Of the ores sold in Cornwall in 1856, the highest percentage for copper was 11¼, the lowest being 2½. This must not be understood as the copper contained in select specimens, but as the per-tentage of the mass of ore sold. In the boxes in this case are shown the ores in their various stages of preparation until they pass into the hands of the smelter.

Copper smelting, which is conducted in this country almost exclusively at Swansea, in South Wales, involves a somewhat elaborate series of operations, of which a very bare outline must suffice. The dressed ore having been calcined in a reverberatory furnace, is fused to the condition of "coarse metal," which, after calcination, is melted with certain oxidized copper ores, and the "white metal" resulting from this fusion yields, on roasting, a crude variety of copper, which is subsequently refined by exposure to oxidizing influences in a reverberatory furnace. During these operations the sulphide of iron in the ore is converted into an oxide, which, combining with the siliceous matters present, forms a fusible slag; and the iron being thus removed, the sulphide of copper suffers decomposition, its sulphur being evolved, whilst the oxide of copper, formed during refining, is reduced in the final operation of toughening. In this process the surface of the metal is well covered with anthracite, and a pole, usually of green birch, is held in the liquid metal, the evolution of gaseous matter causing considerable ebullition. This operation of poling is continued until, by the assays which the refiner from time to time takes, the metal is shown to be in the best condition. This operation requires great care; both under poling and over poling being found injurious.

The various stages in the Welsh process of copper smelting are illustrated by a fine series of specimens presented by Mr. Vivian.

Copper passes into the market in the conditions of cake (ingot) and sheet copper of various descriptions. That used for making brass is granulated, that its surface may be increased, so as to combine more readily with zinc or calamine. The granulation is effected by pouring the metal in a molten state into a vessel pierced full of holes, supported over a cistern of water. When it falls into hot water the copper assumes a round form, and is called bean shot, and when into cold water, from its assuming a ragged appearance, it is called feathered shot. Copper is also cast, chiefly for exportation to the East Indies, in pieces of the length of six inches, and weighing about eight ounces each; these are called Japan copper. By the side of these will be found an ingot of real Japan copper brought from Shanghai.

Table-case 20.—In this case are exhibited some interesting specimens illustrating certain continental processes of copper smelting. The treatment of the remarkable Kupferschiefer or copper slate (p. 83) is here illustrated. This schist, which is extensively smelted in the neighbourhood of Mansfeld, contains on an average not more than three or four per cent. of copper, with a small proportion of silver. After calcination for a considerable time in large heaps, the ore is mixed with a certain amount of slag and flux in the form of fluor-spar, and the mixture fused in a cupola furnace; the product being subjected to successive roastings, until at length a concentrated regains is obtained from which the silver is extracted, and the copper-bearing residuum subsequently smelted. At the time this series was obtained the silver was extracted by Augustin's method, which is accordingly here illustrated, but at present a somewhat different process is adopted. The crude copper is refined in a reverberatory furnace, the refined metal being run out into two external basins, where a little water is thrown on its surface, in order to determine the solidification of the superficial crust; which is removed in the form of a thin circular plate or rosette; more water is now thrown on the fused mass, and other discs are successively obtained, until the whole of the charge has been removed. By the side of these German specimens is a small group illustrating the process of copper smelting at Fahlun, in Dalecarlia, and in the lower part of wall-case 17 will be found a fine sample of the celebrated, but by no means rich, ore of this district.

Tin smelting

Table-case 20.—In this case will be found an old block of tin obtained from the tin district of St. Agnes, and in the adjacent Wall-case, No. 10, are some other ancient blocks of Cornish tin. Such blocks are called Jews' tin, and the rude furnaces, which are not unfrequently discovered in connexion with them, are known as Jews' houses. This arises from the fact that during the reign of John, and subsequently, the tin mines of Cornwall were farmed by the Jews. Those blocks, and the furnaces named, are probably much older than this; tkey possibly belonged to the times when the Phoenician merchants traded with Britain for metals. A model of a remarkable block of tin, which was fished up from off St. Mawes, at the mouth of Falmouth harbour, will also be found in Case 10. The original block is in the Museum of the Royal Institution of Cornwall, at Truro. Sir Henry James has recently shown, with much ingenuity, that the form of this block was peculiarly adapted for its transport, both by land and water.

Tin smelting is a simple operation, conducted either in the reverberatory furnace or in the blast furnace. The houses in which the first plan is adopted arc called smelting houses; those in which the latter process is employed, blowing houses. The tin ore, having been roasted and washed, is mixed with powdered anthracite; and a small quantity of either slacked lime or fluor spar, which serves as a flux for its siliceous impurities, is mixed with it previously to its being placed in the furnace and smelted.

During more than six centuries the tin paid a tax to the Earls and. Dukes of Cornwall. The blocks of tin were subjected to a process called "coining," and certain towns were fixed upon as coinage towns. The blocks of tin—rectangular masses—weighing about 3.34 cwts. each, were sent to the coinage Hall; a corner of each of the blocks was struck off (see Coinage pieces in case), and examined by Duchy officers appointed for the purpose, in order to see that the tin was of proper quality; the blocks were then stamped with the Duchy seal, the dues paid, and the blocks permitted to be sold. ny an Act of Parliament of August 16, 1838, the duties payable on the coinage of tin in Devon and Cornwall were abolished.

The Stannary Courts of Cornwall are now supported by a small tax upon all the ores raised in that county and in Devonshire.

The finer varieties of tin, known as grainy tin, which are used principally by the dyers, are usually prepared by heating blocks of that metal in a bath of melted tin, which, at a certain temperature, are broken by a blow from a heavy hammer.

Oxland's process for separating wolfram (a double tungstate of iron and manganese) from tin.—This process was first introduced at Drake Walls tin mine near Tavistock. It consists in mixing with a little carbonate of soda, tin whits,—that is, the dressed tin from the stamps floors, ready for the burning house. Whits appears to signify whites, as indicating the white metallic look of the washed ore, from the presence of iron and of arsenical pyrites. The tin from the burning house is sorted into jigged fluran, that is, very small—smales, smalls—slime and rows, i. e. roughs. The mixture is then heated to redness in a reverberatory furnace, when tungstate of soda is formed, and the oxides of iron and manganese are liberated. The tungstate of soda, which is a soluble salt, is readily removed by water, and the oxides of iron and manganese are separated from the lixiviated tin by washing. The tungstate of soda is now collected and employed, amongst other things, for rendering textile fabrics non-inflammable. The tungstic acid in a state of purity is also used in the manufacture of steel. (See Table-case, 41.)

Ancient Bronze Weapons, &c.—These are placed with the tin for the purpose of showing that at a very early period the use of that metal as a substance capable of hardening copper, and producing therewith that useful compound metal, bronze, was known.

The art of casting bronze is traceable to the remotest antiquity, and nearly all the bronze colts, scythes, spears, arrow heads, and swords, together with bronze statues and coins which have been discovered, have a similar composition, and that the best, for producing the required degree of hardness. Ancient warlike weapons have usually been found to contain 87½ parts of copper and 12½ tin in 100 parts..

Zinc smelting

Table-case 24.—Agricola, and others in his age, regarded calamine as an earth containing no metal, although it had long been employed in the manufacture of brass. Van Swab in 1742, and Magraf in 1746, separated zinc from calamine by distillation in close vessels. Pott, in 1741, wrote a dissertation on zinc, in which he speaks of it as a semi-metal. The name zinc first occurs in Theophrastus Paracelsus. Agricola (De Re Metallica) calls it contrefeyn. Boyle names it speltrum. It was also called spianter and Indiain, tin. There is every reason for believing the story to be correct which refers our knowledge of the metallurgy of zinc to the Chinese. It is said that an Englishman took a voyage to China for the purpose of learning the art; that he returned and established works at Bristol, where zinc was obtained by distillation per descensum. Dr. T. Lawson appears to have been intimately connected with the early zinc works in this country; and to have associated himself with Mr. Champion, of Bristol, in the establishment for smelting calamine, about the year 1743.

The zinc ore, whether calamine or blende, is first roasted, and the oxide thus obtained reduced by smelting with carbonaceous matter. In this country the reduction is effected in a crucible, provided at the bottom with a tube, through which the zinc vapour descends.

The celebrated Vieille Montagne ores have been noticed at p. 86. The Abbe Deny first established the smelting works, which passed into the hands of the Mosselman family in 1813, and in 1837 into the possession of the present proprietors, the Vieille Montagne Zinc Company. The distillation is conducted in a series of clay retorts, furnished with cast-iron conical condensers.

Zinc is employed largely in the manufacture of brass, it is also used for covering sheet iron (gateauized iron) for baths, water tanks, and pipes; plates for the engraver, and for zincography, and a variety of other purposes, including the manufacture of the pigment zinc white, oxide of zinc..

Brass

Table-case 24.—In the arrangement of these table-cases we have first the pure metals, copper, tin, and zinc; then copper and tin, forming bronze; and finally copper and zinc, forming brass. This alloy is well known, and requires but little explanation.

For the production of differently coloured brasses, and to meet the required conditions of various manufacturing processes, the proportions of copper and zinc in brass are infinitely varied..

Antimony

Table-case 24.—This metal is always extracted from the tersulphide (pp. 79, 86), which is separated from its associated earthy impurities by simple fusion, and in this state is known as crude antimony. By careful roasting, the sulphide is converted into an oxide, which is then reduced to the metallic state by fusion with carbonaceous matters. Antimony is largely used in the preparation of type metal, which consists of six parts of lead and two of antimony; the common stereotype metal being but one part of antimony with six of lead; and in other proportions it forms the alloy on which music is engraved. Many antimonial compounds are employed in pharmacy, as tartar emetic, James's powder, &c., and from some of these medicinal preparations having disordered the inhabitants of a monastery, the metal is said to have derived its name (anti-monk) antimony..

Arsenic

Table-case 24.—The substances containing arsenic usually hold some sulphur in combination. The ores are placed on the sole of a reverberatory furnace, through which a current of air is allowed to play. The sulphur present is converted into sulphurous acid, and carried away by the chimney, while the arsenious acid (white arsenic) produced is condensed in chambers prepared to receive it. To obtain pure arsenious acid the first products thus directly obtained are subjected to a second sublimation in cast-iron tubes provided with cast-iron receivers.

A considerable quantity of the arsenic (arsenious acid) produced in this country is exported to Russia, and is used, it is said, largely in preparing some of the finer skins and furs. But the largest quantity of arsenic is employed in the manufacture of emerald green..

Plattner's gold process

Plattner's method of gold extraction is used at Reichenstein, in Silesia, for the treatment of residues of arsenical ores (lölingite) containing about 1¼ ounces of gold to the ton, and about 5 per cent. of arsenic. Some four hundredweight of these residues are treated with chlorine gas in glazed earthenware vessels for five or six hours. The chloride of gold produced by this means is then washed out with water, an operation that requires from six to seven hours. The free chlorine in the aqueous solution so obtained is neutralized with ammonia, and the gold separated by sulphuretted hydrogen gas as sulphide, which is reduced, by calcination, to metallic gold. The finely divided metal is afterwards united by cupellation with lead..

Bismuth

Table-case 24. — The ready fusibility of this metal renders its metallurgical treatment exceedingly simple, the metal being readily separated from any foreign matters by fusion. Some singularly beautiful examples of bismuth, crystallized artificially, are introduced. The iridescence is given to the surface by the regulated action of heat. Bismuth is used in the formation of type metal, pewter, solder, and fusible metal. An alloy of bismuth 8, lead 5, and tin 3, will melt at a temperature less than that of boiling water..

Cadmium

Table-case 24. — This somewhat rare metal is extracted from the zinc smelted from cadmiferous blende. Specimens of metallic cadmium are shown in the form of ingot and sheet. The sulphide, known as Cadmium yellow, is employed by artists; but the metal has not yet found any important application in the arts..

Smalts and other Cobalt colours

Table-case 24.—The preparation of the beautiful cobalt blues was discovered in Saxony about 1540, and it has since that time been carried on extensively in that country. The cobalt in the ores is converted into oxide by roasting, and the oxide of cobalt thus produced is vitrified with the addition of pure potash and silica. Since cobalt is usually associated with many other minerals, the processes connected with the preparation of smalt are of a delicate character. Smalt is a cobalt glass; this ground to fine powder and carefully washed is applicable to all purposes in which a cheap and durable blue is required as a paint, and for giving a blue tint to paper or linen. Pure stash may be used for painting and colouring glass and porcelain, but for delicate purposes the oxide of cobalt is employed. For colouring earthenware the roasted ore, with an addition of powdered flint, which is sent into the market under the name of Zaffre or Saflor (a corruption from sapphire), is employed; when mixed with the proper proportion of potash, the colour required is produced in the process of firing the ware. In this case will be found all the colours produced by chemical treatment from this metal. The silicate of cobalt and potash forms smalt, and cobalt or Lickner's blue; oxide of cobalt and oxide of zinc, Rinman's green; phosphate of cobalt with alumina, Thenard's blue; arsenite of cobalt, purple; silicate of cobalt, pink..

Nickel and German Silver

Table-case 24.—The metallurgy of nickel is kept a secret by the manufacturers. It is however produced in large quantities to meet the demands of the makers of German silver. The best German silver is said to be composed of copper 8 parts, nickel 4 parts, and zinc 3½ parts. A common variety is made of 8 parts of copper, 2 parts of nickel, and 4 parts of zinc.

Several white metals bearing different names, such as nickel silver, albata plate, &c., are only varieties of the German silver. An ornamental casting in German silver, showing the character of the metal as it comes from the mould, is in Case 14..

Lead smelting

Table-case 37.—The processes of smelting lead and of separating the silver from it were known at a very early period. The book of Job, which is perhaps one of the earliest of the written records which have descended to us, clearly describes the metallurgical and mining processes; and in Jeremiah we find, "the bellows are burned, the lead is consumed of the fire; the founder melteth in vain. * * * Reprobate silver shall men call them." This passage proves the knowledge of the processes of desilverizing lead by oxidation, such as until of late years we have commonly employed. Ancient writers inform us that lead was found so plentifully, and so near the surface of the ground, that it was found necessary, in the earlier period of the Roman occupation, to make a law limiting the quantity to betaken each year. The traces of Roman lead mines are very extensive, and the discovery of Roman pigs of lead by no means uncommon. These were usually stamped with the name of the emperor under whose reign the lead had been produced. One of these Roman pigs of lead will be found in the collection, and two casts from other pigs which have been discovered. The original pig was one of fifty found in an old smelting work discovered near Orihuela, Valencia, Spain (Wall-case 44).

The following are the inscriptions upon the Roman pigs of lead :—

C • IVL • PROTI BRIT • LVT • EX • ARG •

M • PRO • SCIEIS • M • F • MAIG

IMP :VT • SP • VII • T • IN • V • COS

LVT Mr. Wright conceives is an abbreviation of lutum, washed, and the EX • ARG• he thinks is explained by the following passage in Pliny, Nat. Hist. lib. xxxiv.—Plumbi nigri origo duplex est; aut enim sua provenit vena, nee quicquam aliud ex se parit; aut cum argento naseitur, mistisque venis conflatur. In Pennant's Tour in Wales, Lond. A.D. 1810, 8vo., vol. i., p. 79, will be found an interesting description of similar Roman pigs of lead.

The en argento doubtless signifies that from the lead so marked the silver had been separated—that it was indeed refined or soft lead.

With a view to show as clearly as possible all the details of the processes by which lead is separated from its ores, freed of silver, and passed into the market, there are exhibited the various results of dressing, and of the smelting processes—and. tnen the manufactured lead, as sheet lead, shot, and lead pipes.

The process of desilverizing lead was formerly effected by oxidizing the lead, the oxide being from time to time removed from the furnace, leaving the silver upon the bed of bone ashes prepared to receive it. The oxide of lead had then again to be reduced to metallic lead; this process was in every way costly, and unless the per-centage of silver in the lead was large it was not separated.

A process is now employed which is known as Pattinson's process, the late Mr. Hugh Lee Pattinson having patented the method by which the lead is refined.

This chemist discovered that lead consolidated, or crystallized at a higher temperature than an alloy of lead and silver; consequently that, if he kept lead containing silver in a state of fusion at the lowest temperature at which the fluid state could be maintained, Solid masses were gradually formed, which when removed were found to be pure lead. Thus a large portion of lead in a state of comparative purity is removed, and the fluid portion which remains at the last is exceedingly rich in silver. In the MODEL ROOM will be found a drawing, and a model of an arrangement of pots for carrying on the Pattinsonian process. The lead is treated in the manner described, the fluid portion becoming constantly more rich in silver; and this is passed from one pot to the other until, at last, the lead contains so much silver that it is not economical to carry this process any further. This lead is subjected to the oxidizing process and the silver separated.

While the old process was in use in the north of England, if the lead contained less than six ounces "of silver to the ton, it was not found profitable to separate it; and in Wales, if it contained less than 12 ounces they did not refine the lead.

The cost of refining lead, previously to Mr. Pattinson's patent, was from 30s. to 60s. per ton. By Mr. Pattinson's process it is profitable to separate the silver when it does not contain more than three ounces to the ton. Beyond this more silver is now obtained from the lead than formerly; Pattinsonized lead never contains more than seven pennyweights of silver to the ton, when the process is properly performed, while the old refined lead seldom contains less than an ounce per ton, and frequently much more.

The quantity of lead now produced is above 70,000 tons per annum; certainly from more than half of this the silver is separated. This lead will hold on the average from five to eight ounces of silver to the ton. On the lead formerly refined there is a saving of at least three ounces of silver on each ton of lead. The result of this discovery may be stated in round numbers to be a saving of 60,000l. per annum, which was formerly wasted.

Stereotype Blocks of Fusible Metal for Calico Printing. Table-case 37.—Printers' type requires a hard and fusible metal, which does not contract materially in cooling. By combining 20 parts of antimony and 80 of lead, an alloy is produced which fulfils these conditions.

Britannia Metal. Table-case 37.—This is an alloy of antimony, tin, bismuth, and copper. Samples are shown in the form of ingot and sheet, together with some castings..

Amalgamation of Silver ores

Table case 37.—The process of the amalgamation of silver ores as formerly practised at Halsbrücke, near Freiberg, is illustrated by examples of each stage of the process from the ore up to the formation of the amalgam of silver and mercury; and models of the apparatus employed will be found in the gallery of the Model room.

The process consists essentially in roasting the ore with salt (chloride of sodium). As the ores are usually of a very compound character, some complicated reactions ensue; the main result, however, the conversion of the sulphide of silver into chloride of silver. is effected. This is mixed with mercury and some fragments of wrought iron, and, being placed in revolving casks, the mass is kept in motion for about 20 hours, and the amalgamation is complete..

Mercury

Table-case 37.—Some mercurial ores from Idria in Austria, and from Hungary, are here associated with the metallic mercury and the vermilion prepared from it.

At Idria the sulphide of mercury is worked in a formation chiefly composed of black limestone associated with an argillaceous schist, with which it is so intimately mixed as to appear to have been formed contemporaneously with it. These mines were discovered in 1497. The workings are carried on by means of small galleries, as the rock is too pliable to admit of large excavations. The ore, which is principally bituminous cinnabar associated with native mercury, is obtained at a depth of 850 feet from the surface. On submitting the ore to distillation, the sulphur is expelled, whilst the mercury is volatilized and collected in a series of condensing chambers.

If mercury is rubbed with sulphur in a mortar the black sulphide, Ethiop's mineral, is produced. If this powder be heated red hot it sublimes, and if a proper vessel be placed to receive the sublimed substance, a cake of a fine red colour is obtained, called cinnabar; this being reduced to powder forms the vermilion of commerce..

White lead, &c.

Table-case 37.—A small group of specimens illustrating one of the processes employed for the manufacture of this pigment is here introduced. Metallic lead, cast into the form of gratings, is exposed to the action of the vapour of vinegar in beds of fermenting tan. The basic acetate of lead first formed is decomposed by the carbonic acid present, and in this way is obtained a carbonate of lead,₁ which when purified by washing and levigation is ready for use as a pigment. When white lead is roasted it suffers decomposition, and the residuum, consisting of oxide of lead with a little carbonate, is employed under the name of orange lead. Litharge is obtained by oxidizing lead in a reverberatory furnace, and the product when further roasted forms the higher oxide known as red lead.

Iron and steel manufacture

Table-cases 41 and 45.—In well marked divisions the results of the processes of smelting the ores of iron are shown from the following iron furnaces :—

Whitehaven Iron Works	Cumberland
Low Moor Iron Works	Yorkshire
Bowling Iron Works	Yorkshire
Farnley Iron Works	Yorkshire
Russell's Hall Iron Works	South Staffordshire
PLymouth Iron Works	Glamorganshire
Dowlais Iron Works	Glamorganshire
Maesteg Iron Works	Glamorganshire
Monkland Iron Works	Lanarkshire.

It is not intended to give any detailed account of the metallurgy of iron. The ordinary processes are, however, of the following order :—

The "mine," that is, the iron ore, is subjected to calcination. To effect this the ore is usually piled in long heaps over a stratum formed of large lumps of coal. Fire is applied to the windward end, and after it has burned a certain distance the heap is prolonged with the same materials in an opposite direction.

In the Model Room the construction of a blast furnace can be studied with its associated blowing machine. In the blast furnace the proper mixture of iron ores and the due quantity of limestone is placed with the sufficient supply of fuel. The limestone, carbonate of lime, is used for the purpose of yielding lime to combine with the silica and the alumina of the ore, which it does, forming a fusible double silicate of lime and alumina, appearing as a slag; while the iron is separated and collected in afluid state at the bottom of the furnace, from which it flows out at the proper time and is collected in sand moulds prepared for it, producing the masses known by the name of "pigs."

As an intense heat is required for smelting iron ores, a strong blast of air is constantly injected through tuyeres (iron nozzles connected with pipes leading from the pneumatic apparatus), which are fixed in holes just above the level of the tymp, or block of sandstone, which is adjusted at the base of the furnace, this blast being urged by a steam-engine constructed for the purpose. By employing heated air a saving is effected in the process of smelting, and it is now common to make the air traverse pipes which are heated by a separate furnace, before it enters the blast furnace. Iron prepared by the hot-air process is called hot blast iron, but when the air is admitted to the blast furnace cold it is known as cold blast.

The crude metal obtained from the blast furnace is termed cast iron, of which there are three varieties :—

Grey cast iron, exhibiting a finely crystallized surface.

Mottled cast iron, lighter in colour than the grey, and presenting when broken a peculiar mottled appearance.

White cast iron, hard and brittle, with a radiated lamellar fracture.

Cast iron in all varieties contains a considerable amount of carbon, sometimes as much as five per cent., together with small quantities of silica, sulphur, phosphorus, &c. These impurities are oxidized during the conversion of the cast iron into pure or malleable iron. This is effected by taking advantage of the fact, that though iron and carbon are both combustible, yet carbon is the more so of the two; if, therefore, iron is melted in a reverberatory furnace and exposed to a current of air the carbon is burnt out. The operation is called puddling, and instead of relying entirely on the action of the air to remove the excess of carbon, a certain quantity of the oxide of iron or of manganese is employed. As the carbon passes off as carbonic oxide the iron becomes less fusible, and ultimately breaks up into an incoherent granular mass like sand. The heat is then increased, these grains agglutinate, and being worked up- into a ball, the mass is taken from the furnace, and subjected to great pressure by machinery. The lump of malleable iron thus obtained is then passed through a succession of rollers, turned by a powerful steam engine, each pair of roll6rs having a smaller interval than the preceding; by this means the mass is gradually elongated into a bar, and at the end of the rollers furthest from the furnace it passes out as the soft bar iron of commerce. See Nos: 18, 10; 20, 26 and 46 in the Hall.

Steel manufacture

Table-case 41.—Steel may be regarded as representing a condition intermediate between cast iron and bar iron, in containing about P5 per cent. of carbon. Steel is sometimes formed directly from the ore or from cast iron, by regulating the action of the fuel and of air in the furnaces. The most common process,' however, is that of cementation. Bars of iron are imbedded in powdered charcoal in boxes, and exposed for a long time to a full red heat. To prevent the charcoal from burning away, and to confine its action as much as possible to the iron, the whole is covered with some sand or earth which will not easily vitrify. In Sheffield a stiff ferruginous mud, called wheelswharf,— the stuff which is produced by the wearing of the grindstones,—is generally used, and every unnecessary aperture is carefully closed. The trough containing the iron and charcoal, which holds from 13 to 17 tons of metal, is then exposed to the action of fire, which is maintained at a high intensity for some days.

Blistered Steel is produced by the formation within the mass of a gaseous compound of carbon and oxygen, which occasions the formation of bubbles in the metal.

Shear Steel.—Blistered iron bars are bound together, and being placed in a wind furnace brought up to a welding heat, the bars are formed by heavy hammers into a rod about two inches square; it is then cut in the middle, the two halves placed together, and welded again as before. By this process the steel is not liable to the flaws so frequent in blistered steel. As the welding may have been more or less frequently repeated, so the value of the steel varies, and it is known in the metal market as half shear, single shear, or double shear. Faggot steel is manufactured by a process analogous to that of shearing.

Cast Steel.—Blistered bars are broken into small pieces and put into a barrel-shaped crucible of Stourbridge clay, capable of holding about thirty pounds of metal. This is placed in a draught furnace, which is fed with the best coke, and every means adopted for producing a very high temperature. In about four hours the fusion is complete, and, being withdrawn from the fire, the molten steel is poured into a mould. Great attention is required in this process, the quality of the steel depending entirely upon the management of the nicker.

Sheet and Bar Steel, for saws, &c., is made by repeatedly passing the metal at a red heat through large metal rollers. Bar Steel is made in a similar manner, the rollers being grooved to form either flat or round bars. An examination of the Model of a Sheffield Steel Manufactory (No. 33) at the north end of this Museum, which includes the furnaces, rolling mills, and forge, will aid every one in forming a correct idea of the processes of steel manufacture, which are here so very succinctly described.

In the Model Room, against the wall, is a stand containing specimens of every variety of steel sent into the market. These, and the model, were presented to the Museum by Messrs. Naylor, Vickers, & Co., of Sheffield.

Hardening and Tempering.—Steel is commonly hardened by being plunged, when red hot, into water; it is afterwards tempered by being heated until the surface assumes a tinge varying from a light straw colour to a deep blue. An interesting series of specimens of steel at the different colours for tempering will be found in this case. The process of tempering steel is one demanding the most exact attention from the manufacturer.

Steel springs of several kinds, and steel dies, such as are employed for striking the coinage of the realm, medals, &c., are here exhibited, and other examples of the application of the metal will be found among the objects in the central series.

Tin plate

Case 41

This is sheet iron coated with a thin layer of tin. The iron, which must be manufactured with much care, coke being used, is rolled into sheets of the required thinness.

The sheets are cut into rectangular pieces, and these are freed from every particle of adhering oxide, or any impurities which would inevitably prevent the adhesion of the tin. The plates are bent into a saddle or ,f shape, ranged in a reverberatory oven and heated to redness. They are withdrawn, plunged into an acid bath, and once snore exposed to ignition in the furnace, by which they are said to be scaled. The plates are passed through iron cylindrical rollers, and then immersed for ten or twelve hours in an acidulous lye, made by fermenting bran water, after which they are exposed to the action of dilute sulphuric acid, until they become perfectly bright. Being cleaned off with bran, the plates are plunged into some melted tin, which is covered on the surface with about four inches of tallow. The plate subsequently is dipped into another pot of metal, called "Wash-pot No. 2," and then cleaned off by the workman. A skilful tin-plater can pass 5,625 plates through his hands in twelve hours..

Zinced Iron. Galvanized iron

The process is analogous to that of tinning iron, though differing in its details. An alloy of zinc and iron, formed in the manufacture of galvanized iron, is in this case..

Supposed alteration in the structure of iron by vibration

Case 41.

Attention was directed to the influence of long-continued vibration on the structure of iron by Mr. Nasmyth in 1842. His experiments went to prove that an original fibrous or ligneous structure was changed into a crystalline one. The process of "cold swaging" was found to produce this molecular disturbance to so great an extent as to render the iron liable to break with the slightest blow. Mr. Lucas, between this and 1844, made a great many experiments which appeared to prove that long-continued vibration certainly produced this effect, and not only that iron but that even wood was subject to this weakening influence. Some engineers have, however, questioned the facts brought forward, and are disposed to think that the fracture is dependent upon the kind of blow with which the iron is broken;—a dull blow producing a fibrous, and a sharp one a crystalline fracture..

Railway axle

Railway axle, as bent by an accident without breaking, and some examples of peculiarities in construction, will be found in the Model Room..

Ancient use of iron

(Case 41.)

Mr. Layard brought from Assyria the bronzes in this case, which were constructed for the purposes of support of some kind. Dr. Percy found that the bronze had been cast round a support of iron, by which means the appearance of considerable lightness was attained, while great strength was ensured. This discovery proves that the metallurgists of Assyria employed iron for the purpose of imparting strength to the less tenacious metals which they employed in their art manufactures. The bronze, as analysed in the Metallurgical Laboratory, consists of copper ^88.37, tin 11.33.

By the side of these ancient specimens are examples of some modern experiments of a similar kind, which have been made in consequence of this discovery..

Crystalline slags

Table-case 41

An interesting collection of slags obtained from furnaces is associated with the iron in this case, as illustrating some curious results of the metallurgy of this metal.

An examination of these slags was made by Dr. Percy, who reported, in 1846, to the British Association the results of his inquiry. The production, under the peculiar circumstances in which these slags were formed, of crystalline minerals, in many respects similar to some which are found in nature, renders the inquiry into their chemical constitution and physical conditions a peculiarly interesting one; and in its bearings upon many geological phenomena it is most especially so, as showing the influences of the long-continued action of high temperature upon mineral combinations and crystalline structure.

With these slags are exhibited some fine specimens of the bright copper-red cubic crystals of a peculiar compound of titanium (p.79). These crystals, to which Dr. Wollaston first drew attention, were formerly thought to be pure titanium, but they are now known to be nitride of titanium with cyanide of titanium.

The specimens of crystallized oxide of zinc from the iron furnaces of Westbury are also interesting.

Many other objects, belonging properly to the metallurgical series, are distributed through the cases in the central area, to which we now pass.

Central cases and models

Model of the Chain of Puys, Auvergne

Presented by G. Poulett Scrope, I.R.S., &c. No. 11, opposite the entrance from Hall.

Little more than a century ago two French travellers returning from Italy observed that the rocks in certain parts of their route through Central France bore a striking resemblance to the volcanic products of Vesuvius. Although at first received with considerable opposition, the truth at length became established, that at a comparatively recent geological period the interior of France had been the theatre of energetic and frequently-repeated volcanic action. One of the most interesting groups of these extinct volcanos is represented in the model before us.

The volcanic hills of the department of the Puy-de-Dome form an irregular chain, running nearly north and south, and rising from the great plateau of granite which forms so prominent a feature in the geology of Auvergne. The surface of this granite presents several depressions, formerly occupied by lakes, the existence of which is now marked by certain fresh-water deposits, of which the largest forms the fertile plain of the Limagne, represented on the eastern side of the model. Passing westward from the alluvial valley of the Allier, we cross the calcareous marls and other lacustrine deposits on the margin of the Limagne, and reach the eastern escarpment of the granitic table-land which, extending in width for about 12 miles, slopes on the western side to the valley of the Sioule. The chain of "puys," which rises from this platform, includes about 70 volcanic hills, of which the largest is the Puy-de-Dome, a mountain rising 4,844 feet above the sea level. Most of these hills are composed essentially of the scoriæ, lava, and other volcanic products, which, accumulating around the orifices of eruption, have formed conical hills, often presenting at the summits well-defined craters, from which, in many cases, distinct streams of lava may be traced. The Puy-de-Dome and a few other hills consist, however, of a peculiar trachytic rock called domite. A descriptive label, by Mr. Scrope, accompanies the model, and a notice will also be found in the Catalogue of Models. For further information see "The Geology and Extinct Volcanos of Central France," by G. Poulett Scrope, M.P., F.R.S., &c.

In the drawers beneath the model is an interesting group of rock specimens illustrating the geology of the district, presented mostly by Dr. C. Le Neve Foster, B.A., F.G.S..

Gun barrels

Table-case 13.

The principal object in the manufacture of a gun barrel is its strength. It should possess so much tenacity as will ensure its resisting the sudden shock to which it is exposed in projecting the ball by the explosive force of gunpowder. Experience has proved that this is obtained by the use of iron which has undergone peculiar processes of manufacture. Scrap iron is employed for inferior barrels, horse-shoe nails and scrap steel are taken for superior kinds; these are welded into flat bars; the bars of iron and steel are again welded together, and formed into square bars. If a number of straight bars were welded together to form a barrel, they would be liable to open along the lines of welding; at all events, such a gun barrel would not be nearly so safe as one made of the same bars formed into a helix, and then welded into a tube. These two conditions are shown in the specimens in the case.

By altering the arrangement of the fibres of the iron, there is produced a different pattern on the surface of the barrel when they are rendered visible by polishing. Thus one bar is twisted to the right, another is twisted to the left hand. Now these when twisted on a mandril are welded into a barrel, which will exhibit an involved pattern. If they are combined, or if an untwisted bar is placed between them, and they are then turned and welded, we have a still more elaborate pattern as the result. Thus the gunsmith possesses the power of varying extensively the patterns upon the barrel.

From the welding-shop the barrel passes to a workman who duly examines its soundness, and, if it is required, straightens it. The barrel is then transferred to the boring mill, and properly ground; it passes through a subsequent process of fine boring. The exterior of the barrel is ground by the grindstone, and then filed with a smooth file and finished; those last operations are commonly performed by women. Barrels are browned by the application of a combination of iron and copper in nitric acid, to which either spirits of wine or sweet spirits of nitre have been added..

Swords

Table-case 48.

The oriental sword blades have always been celebrated, and their superior character has been stated to, and probably does, belong to the very excellent iron ores which are obtained in various parts of Asia, and to the reduction of those ores by charcoal. Swords and daggers from the Punjaub, Ispahan, and Borneo are in juxtaposition with specimens of the Damascus, Andrea Ferrara, and Toledo blades.

The finest oriental sabres are those, professedly of great antiquity, presumed to have been made at Damascus in Syria, Ispahan in Persia, and at Cairo in Egypt. The characteristics ascribed to the real Damascus blades are, extraordinary keenness of edge, great flexibility of substance, a singular grain of fleckiness always observable on the surface, and a peculiar musky odour given out by any friction of the blade, either by bending or otherwise.

Milan, Bilboa, and Toledo furnished the Crusaders with their swords, Milan appearing to have been the great mart for the sale of both the Spanish and the Italian weapons.

Toledo under the Romans, and in the time of the Moors, was celebrated for the admirable temper of its swords, "which is chiefly attributable," says a writer on the Toledo blades, "to some favourable quality in the water of the Tagus, used in tempering the steel." The swords manufactured on the banks of the Guadalquiver are said to be very inferior, from this cause, to those made by the Same workmen on the banks of the Tagus.

Andrew of Ferrara has associated his name with the swords of his manufacture, "Andrea Ferrara." This sword maker was considered, in his time, to be the only man in Great Britain who knew how to temper a sword in such a way that the point should bend to touch the hilt and spring back again uninjured. He is said to have resided in the Highlands of Scotland, where he employed many men in forging his swords, devoting his entire attention to tempering them. This operation he performed in a dark cellar, the better to enable-him to distinguish the colours produced by heat on the blade, upon which everything depended.

Swords appear to have been made at Birmingham from a very early period : Hutton, the local historian, says, long before the landing of Cæsar. Sword making is, however, now one of the staple trades of Birmingham; the forges of Sheffield, however, furnish a large quantity of bars of steel, called sword moulds. In Case 13 is shown the mould; the fastening of the tang, which is of iron; and the results after the different stages of forging. It is hardened by heating it until it becomes worm red, and then dipping it, point downwards, in a tub of cold water. It is tempered by drawing it through the fire several times, until it exhibits a bluish oxidation on the surface. It is subsequently polished and mounted..

Model of the Isle of Arran

By Professor A. C. Ramsay, LL.D., F.R.S. No. 9.

This model is on a horizontal scale of twd inches to a mile. The vertical heights are somewhat exaggerated. The best idea of the form of the more mountainous part may be obtained by bringing the eye to the level of the model at the S.E. corner. These mountains consist of granite, forming a circular mass at the north end of the island, about eight miles wide in all directions. The highest point (Goatfell) is 2,959 feet above the level of the sea, and rising directly from the shore, it looks even higher. This mass is surrounded by clay slate, chlorite slate, gneissic and other metamorphic rocks, the metamorphic action having been induced by the granite which they surround. In their turn they are overlaid by the old red sandstone, on the east at Glen Sannox, and on the south between Brodick and the west coast north of Mauchrie Water. It is in great part conglomeratic, and pebbles of the underlying metamorphic rocks are contained in it, showing that they were altered before the deposition of the old red sandstone.

The coal measures (lower coal measures) rest on the old red sandstone at Brodick bay, and south of Glen Sannox, but between these points they rest, first on the slaty rocks, and then on the granite, showing that they lie on the older strata unconformably. They are also found about three miles off' the N.E. coast of the island, lying on metamorphic slaty rocks. The limestones, which are interstrati-fied with the sandstones and shales, contain the usual carboniferous fossils. Coal measure plants are found in the sandstones and shales, and thin beds of coal occur near the salt pans. On the S.W., coal measures also appear in the valleys where the trap rocks have been removed by denudation. The new red sandstone overlies the coal measures at the Cock of Arran (N.E.), and also forms the major part of the coast of the S.E. of the island. It is doubtful, however, whether these rocks do not in reality form only a higher part of the coal measures. The major portion of the south part of the island consists of felspathic traps and greenstones of comparatively late geological date, for they have broken through the stratified rocks indiscriminately and overflowed them, so that in general it is only in the valleys that the underlying strata of coal measures, &c., have been. exposed by denudation.

Sulphate of baryta is obtained in tolerably large quantities on the hill to the south of Glen Sannox, and in the bed of a small torrent originating in Corrie na Chiodh..

Eozoön In Laurentian Serpentinous Limestone. No. 8.

Presented by Sir W. E. Logan, Director of the Geological Survey of Canada.

The Laurentian rocks of Canada, which are developed on so vast a scale in the country north of the St. Lawrence, consist chiefly of enormous deposits of gneiss, containing in certain parts intercalated beds of crystalline limestone. The system is clearly separable into an upper and a lower series, and from the uppermost limestone-band in the lower group the block before us was obtained. Considerable interest naturally attaches to the recent discovery by Sir William Logan of organic remains in these metamorphic rocks, which are the oldest stratified deposits at present known. The fossil, which has received the name of Eozoon Canadense, is referred, by Dr. Carpenter and other microscopists, to the group of forami-nifera. These are animals of extremely simple organization, each foraminifer consisting essentially of a gelatinous mass called "sarcode," usually enclosed in a calcareous covering. In the eozo8n this calcareous shell is but little altered, whilst the easily-perishable sarcode is replaced by certain serpentinous minerals..

Art applications of the metals

Case 14.

The object of the articles grouped in this case is to show the characters of the metals in a pure and a mixed state, and to illustrate their application to works of art and to art manufacture.

Statuettes in tin and copper show the characters of the metals in their ordinary states. One in brass exhibits the result of combining copper and zinc, while those of Raphael and Michael Angelo are bronzes, in the proportion of 90 parts of copper and 10 of tin. The statuette of Humboldt is of zinc, but it has been subsequently coated by the electro-chemical process.

The silver and bronze vases are copied from antique specimens found in Pompeii, and now in the Museo Borbonico at Naples. Corinthian bronze, in which one of them is cast, consists of two-thirds copper and one-third silver. This composition is said to receive its name from its having been discovered by the accidental melting together of statues of copper and silver which were destroyed by fire at Corinth, At least 700 years before Christ the art of casting bronze statues was carried to a high degree of refinement. Pliny informs us that it was during the reign of Alexander that the production of bronze statues received its greatest extension under the guidance of the artist Lysippus, who improved the modes of moulding and casting. Pliny calls these statues the mob of Alexander. Athens is said to have contained above 3,000 bronze statues. Rhodes, independently of its lighthouse and its bronze tower, was decorated with as large a number, and in Olympia and at Delphi they appear to have been no less numerous. We are thus enabled to form some idea of the extent to which metallurgy was carried by the ancients. Electrum was one of the celebrated mixed metals of the ancients, of which we have here an example.

Our standard silver (see Silver Vase) has a composition of 222 silver and 18 copper; by the admixture of the latter metal the required hardness is obtained without interfering with the colour of the silver.

An example of a mixture of platinum and silver will also be found in this case.

The German silver has been already noticed in connexion with the nickel series (p. 108); and the aluminium bronze will be mentioned in the description of an adjacent case (p. 121).

The Bronze Lizards.—Castings of this kind are obtained by pouring upon the living animal a cream of plaster of Paris; this soon sets, and the animal dies. By exposing the plaster after it is dry to a high temperature all the organic matter is destroyed, and a perfect mould is left, into which the metal is poured. Chantry was one of the first to employ a process of this kind, for the purpose of obtaining fae-similes in metal of leaves and flowers..

Chinese bronzes, &c.

Case 18.

Productions of this kind have long been made by the Chinese, and they exhibit very great ingenuity in their modes of moulding, and adjusting the mould so as to secure, as nearly as possible, perfect coating by one operation, without the subsequent use of the tool.

In many instances the model is most carefully made in wax, and all the ornamentation, inscriptions, and the like elaborately finished —this is then covered with the clay which is to form the mould, and when dry the wax is melted out—the metal which subsequently in a fluid state supplies its place fills every part, and thus is obtained a casting of great sharpness and correctness.

The tam-tams and cymbals of bronze of the Chinese are forged with the hammer, as indeed are many of their bronze articles. The composition of these appears to be 78 of copper and 22 of tin. This alloy, when newly cast, is very brittle, but being confined between discs of iron, heated to cherry redness and plunged into cold water, it becomes malleable. The Chinese bell—tshoung—which we render gong, is usually composed of 80 copper, 20 tin; these are worked with the hammer as described. The Chinese frequently employ copper alone, and give it artificially the character of bronze by spreading upon the surface a paste of verdigris, cinnabar, sal ammoniac, and alum, and then exposing the vessel for some time to the action of a moderate fire.

Chinese Mirrors.—Many of these mirrors possess the very remarkable property of reflecting from their polished surface the figure which is wrought upon the back. Chinese copper, some of that metal from Japan, a Chinese lock and key, &c., will also be found in this case..

Electro-metallurgy

Case 22. Head of OCEAN (7). Head of MELPOMENE (51)—presented by Elkington, Mason, and Co.—near the gallery stairs on either side. Specimens in Wall-cases 15, 16, 17. Frame on wall near Case 24.

The discovery of the process of the electrotype, or electro-metallurgy, was first announced to the public on the 4th of May 1839, by Professor Jacobi, of St. Petersburg.

On the 8th of May Mr. Spencer announced to the Liverpool Polytechnic Institution his discovery; and on the 22nd of the same month Mr. C. J. Jordan published in the Mechanics' Magazine a description of his method. Here we have an instance, not an uncommon one, of three men, Jacobi, Spencer, and Jordan, working at the same time upon a most important discovery, without either of them being in the least aware of the researches of the other.

Electro-metallurgy depends upon the law established by Dr. Faraday, that the electricity developed by the change of state, oxidation, of an equivalent of one metal, zinc, would effect the decomposition of an equivalent proportion of another metal, copper, from its solution.

The form of a voltaic battery for the electrotype process is exhibited. A plate of zinc and a plate of copper being placed in some diluted sulphuric acid, an action is immediately established on the zinc; it is first oxidized, and the oxide of zinc formed is converted into sulphate of zinc, by being dissolved in the sulphuric acid. During the oxidation of the zinc, electricity is developed, which passes to the surface of the copper plate. If from each of those plates a copper wire is carried into a solution of sulphate of copper, a piece of plain copper being attached to one wire and connected with the copper plate, and an engraved plate or a medal to the wire connected with the zinc plate, the result will be that copper will be deposited in a metallic form upon the engraved plate or medal, and copper will be dissolved off from the plate on the other wire. In the frame on the wall, near Case 24, is a plate of copper as precipitated, another plate as thrown down upon an engraved surface, which gives all the lines in relief; upon this another deposition being made, the result is, as shown, an exact facsimile of the original plate. As an example of the application of this, the maps used by the Geological Survey of Great Britain are copied from the plates of the Ordnance Survey by the electrotype process; upon the plates thus obtained are engraved the geological lines, signs, and remarks, so that every information required by the public appears on the geological map, without at all disturbing the character of the ordnance map. Many surfaces, such as clay, plaster of Paris, wax, &c., are not conductors of electricity, and consequently upon these metal cannot be precipitated. The late Mr. Robert Murray discovered that black lead, plumbago, rubbed over such articles gave them at once a conducting surface, and rendered them fit for receiving, by the voltaic battery, a metallic precipitate. Thus are formed several of the objects exhibited.

If silver or gold is to be deposited, the oxides of these metals must be dissolved in cyanide of potassium or some such salt. The article being immersed in this, when connected with the battery silver or gold is deposited. This is electro-plating. To prevent the silver from presenting a granular or dead appearance, a few drops of the sulphide of carbon are added to the solution.

The Botanical Specimens, 4.c., of which there are exhibited electrotype coatings, may be prepared by dipping, first the grass or leaves into a solution of phosphorus in sulphide of carbon, then plunging the article into a solution of the nitrate of silver. The thin film of phosphorus left upon the surface occasions a precipitation of a finely-divided coat of silver, upon which, when connected with the battery and placed in the proper solutions, any quantity of either copper, silver, or gold can be deposited. It is impossible to do more than thus indicate a few of the processes by which electro-metallurgy has been carried forward.

The most recent improvements have been the coating of iron with copper, and the electro-chemical deposition of the compound metal, brass, of which some examples are shown..

Aluminium, precious metals, meteorites, &c.

Case 15..

Aluminium

In a state of powder aluminium has been known since the days of Davy; Oersted wrote on it and some of its alloys; and Wohler and other chemists prepared it. M. St. Claire Devine was, however, the first to obtain the metal in a perfectly coherent form. Until recently the mineral called cryolite, a double fluoride of aluminium and sodium, of which a specimen is shown, was the principal source of aluminium; but at present the metal is exclusively obtained from bauxite, a French mineral, containing more than one-half its weight of alumina, together with peroxide of iron, silica, titanium, and water. By heating a mixture of bauxite and soda-ash an aluminate of soda is obtained, and from a solution of this salt, alumina in the state of hydrate may be precipitated by an acid. A mixture of this precipitated alumina with common salt and charcoal is treated with chlorine, and from the double chloride of aluminium and sodium thus formed, metallic aluminium is obtained by the reducing action of sodium. Each stage of the process is here illustrated. Aluminium has a specific gravity of 2.56; that of silver being 10.5. It does not tarnish under circumstances in which silver, tin, and zinc blacken; and alloyed with copper it forms the well-known aluminium-bronze, of which several specimens are here shown..

Precious metals

The most interesting among these are the specimens of platinum and its associated metals.

Platinum was unknown in Europe till about the middle of the last century, when it began to be imported in small quantities from South America, but from its infusibility it was useless.

Dr. Wollaston discovered a method of fusing platinum, and thus of rendering it available in the arts. Platinum first engaged the attention of the Russians in 1824, when rather more than one pood was collected. In 1836 more than 138 poods were obtained, and within a few years the Russians have issued platinum coins of the value of 3, 6, and 20 silver roubles. (See p. 89.)

Meteorites

A small collection of meteorites is here exhibited, including some fine specimens of meteoric iron and several

fragments of meteoric stones. The former consist of iron alloyed with a small quantity of nickel and cobalt, and frequently contain graphite and other minerals; whilst the latter are aggregates of various simple minerals, such as felspar, augite, and olivine. Some of the specimens of meteoric iron show the figures of Widmannstadten, i.e. the crystalline structure developed by the action of nitric acid on a polished surface. Numerous meteorites have fallen in various places, but the origin of these masses is still wrapt in obscurity; the most rational theory is that of Chladni, which may be expressed in the following general terms :—

Through the interplanetary spaces, and it may be through the interstellar spaces also, vast numbers of small masses of solid matter may be moving in irregular orbits; and these, as they approach any planet of powerful gravitation, such as the earth, will be disturbed, and may fall towards its surface.

The theory of Laplace was, that these aerolites were projected from volcanos in the moon. It has, however, been proved that there are no active volcanos in our satellite; consequently this theory cannot be received..

Miscellanea

This portion of the case is in process of arrangement, but several objects of much interest will be found here.

Silver Plating.—The art of overlaying one metal with another of a more valuable character is of great antiquity; but, as far as we can judge, the application of the more expensive metal upon the inferior one was originally merely some method of washing or gilding, or of affixing sheets and foils by means of some adhesive material.

The modern process of "fire plating," so called to distinguish it from the electro-plating, appears to have been first employed in the metropolis. The method is as follows :—

An ingot of copper as shown, or of copper containing a little brass, is prepared, after casting, by filing a perfectly smooth and clean face, which is afterwards carefully scraped; on this a plate of silver, also perfectly smooth and clean, being a little less in size than the copper, is placed so that the bright surfaces shall be in contact. Over the silver is placed a piece of sheet iron of the same size, brushed over with whiting to prevent its adherence to the mass when heated. The iron, silver, and the copper ingot are bound together by means of small iron binding wire; a little borax ground with water is laid around the silver in the space where its edge approaches that of the copper, after which it is ready for the fire. A perfectly clear coke fire being obtained in a small reverberatory furnace, the mass is placed in it, and allowed to remain until symptoms of fusion appear upon the edges of the silver, it is then immediately withdrawn and allowed to cool. If the right time is secured for withdrawing the copper, the silver will be found to have adhered perfectly over every part, and the mass may be submitted to rolling and the processes of manufacture, the silver uniformly extending with the copper. This is illustrated by the ingot and the sheet in this Case.

The process of plating steel blades for dessert knives is also shown.

Silver coined at Aberystwith.—The Cardiganshire lead mines are especially remarkable for the attention which they excited during the latter half of the 16th and the beginning of the 17th century. Sir Hugh Middleton realized a large fortune from those mines, and expended it in bringing the New River from Ware to London. After Sir Hugh Middleton's death, Mr. Bushell, the Secretary of Sir Francis Bacon, bought the mines of Lady Middleton. These mines were extremely profitable to him, and availing himself of an indenture of Charles I., dated 30th July 1637, he established a mint at Aberystwith. Mr. Waller, in his account of the mines of Cardiganshire, says, "He kept a mint at work at the silver mills in Cardiganshire from the bullion he had at this mine, and is said to have clothed King Charles the First's whole army from part of his profit in this work." It is certain that during the civil wars Mr. Bushell sacrificed his fortune in the King's defence, and that he placed himself at the head of a regiment of miners which he had raised in support of the royal cause. Aberystwith Castle was besieged and taken by the Parliamentary forces, and the mint and mines were abandoned. The coins exhibited are some of those coined by this Mr. Bushell.

Gilt Copper Cup obtained from the copper mine of Herrngrund, in Hungary.

In "An Account given by Dr. Edward Brown concerning the Copper Mine at Herrn-ground, in Hungary," the following description occurs:

"There are also two springs of a vitriolet water, which are affirmed to turn iron into copper. They are called the old and the new ziment. These springs lie deep in the mine. The iron is ordinarily left in the water 14 days. I here present you with some pieces of it, and with a heart and chain, formerly iron, but now appearing to be copper. Divers of these pieces I took out of the old ziment. They are hard within the water, and do not totally lose their figure, and fall into powder, as you will perceive by them; they will easily melt. I have sent a piece melted without the addition of' any other substance. ' They make handsome cups and vessels out of this salt of copper. I drank out of one of them when I was at the Verwalter of Herrn-ground, his house. It was gilded over, and had a rich piece of silver ore fastened in the middle of it, and this inscription engraved on the outside :—

Eisen war Ich, Kupfer bin Ich;

Silber trag Ich, Gold bedeckt mich.

Copper I am, but Iron was of old;

Silver I carry, cover'd am with gold."

Phil. Trans. Vol. 5. 1670.

If iron is placed in a solution of sulphate of copper, the iron is dissolved as sulphate of iron, and copper takes its place. This process is termed cementation„ and the cups exhibited are thus produced. The inscription on the cup is Gott zeigt an Mir sein grose Macht der auss Eisen Kupfer Macht, "God shows in me his great power, who out of iron makes copper." The date of this cup is about 1650.

Antimony Cup.—When wine was allowed to stand in these cups, tartarized antimony (emetic tartar) was formed and dissolved, and consequently when the wine was drunk it produced sickness..

Model of the Pass of Mont Cenis. No. 17.

This model shows by the contour-lines the various elevations, and exhibits the physical features of the country. The district represented does not extend sufficiently westward to include the country penetrated by the railway tunnel now in course of construction under the direction of M. Sommeiller.

In the upper part of Wall-cases 8 and 9 are several other illustrations of this system of modelling..

Gold and Silver Ore from Chile. (Underneath)

This specimen is from the Madre de Dios mine, near Coquimbo. It contains gold and silver in the proportion of 12 ozs. of gold and 220 ounces of silver to the ton.

A few other mineral specimens also find place here..

Australian gold, &c. No. 19.

It appears that in 1839 Count Strzelecki discovered traces of gold in Australia, but on relating the circumstance to the Governor of New South Wales secresy was enjoined, and the Count never reverted to the subject. In 1841 the. Rev. W. C. Clarke wrote to a friend in the colony, mentioning that he had found gold ore, but neither of those facts was published in the colony, and they were wholly unknown in Europe. The study of the auriferous tracts of the Uralian Mountains enabled Sir R. I. Murchison, in 1844, to predict the discovery of gold in Australia. "Having," writes Sir R. Murchison, "in the year 1844 recently returned from the auriferous Ural Mountains, I had the advantage of examining the numerous specimens collected by my friend Count Strzelecki along the eastern chain of Australia. Seeing the great similarity of the rocks of those two distant countries, I could have little difficulty in drawing a parallel between them; in doing which I was naturally struck by the circumstance that no gold ' had yet been found in the Australian ridge, which I termed, in anticipation, the 'Cordillera.' Impressed with the conviction that gold would, sooner or later, be found in the great British colony, I learned in1846, with satisfaction, that a specimen of the ore had been discovered. I thereupon encouraged the unemployed miners of Cornwall to emigrate and dig for gold, as they dug for tin in the gravel of their own district. These notices were, as far as I know, the first published documents relating to Australian gold."—Siluria, chapter on the original Formation of Gold, and its subsequent distribution in debris over parts of the Earth's surface.

In 1848, three years before the practical development of the Australian gold fields,—Mr. Hargraves not having proved the value of the diggings until 1851,—Sir Roderick Murchison directed the attention of Her Majesty's Government to the advantages to be derived from a geological survey of the Australian colonies, by the opening out of gold mines. Thus the addresses of Sir Roderick Murchison, on the question of the existence of gold in a locality which he had never visited, and from which he had examined the chief rock specimens only, may be quoted as a proof that geology, like the more exact sciences, is capable of advancing philosophical inductions to very important results.

Of the Auriferous Drift of South Australia we have the following account, by Mr. Alfred R. C. Selwyn, Geological Surveyor of that district, and formerly of the Survey of the British Isles :—

"This formation, of very late tertiary date, varies in thickness from a few inches to 100 feet and upwards. It consists of stratified and unstratified masses of ferruginous clays, sands, and gravel, interspersed with angular and partially rounded fragments of clay slate, sandstone, quartz, &c.

It occurs almost universally, distributed in the gullies, on the flats, and over the hills, occupied by the palmozoic strata, and is, in fact, formed from the decomposition, breaking up, and spreading out of the immediately subjacent rocks; the fragments found in it being, with a few local exceptions, seldom much water-worn, and bearing no evidence of having been transported from a distance. The lowest stratum or bottom almost always varies in colour and character with the nature of the subjacent rock, whether a ferruginous clayey sandstone, forming a red or mottled ferruginous sandy clay or gravel, or a soft felspathic slate, producing a white pipe-clay, &c.

With respect to the origin and present position of the gold, there can, I think, be little doubt, 1st, that the whole of it has been formed in or near the quartz veins which are now seen traversing the palæozoic strata; 2nd, that its present position in the drift is entirely due to the decomposition, breaking up, and spreading abroad of these quartz veins along with the ordinary sandstones, slates, &c. of the district."

Gems from Australia.—Specimens of sapphire, topaz, zircon, and other gems occurring in the alluvial gold-deposits are here exhibited. With these are two Australian diamonds, one of them being the earliest brought to this country. Several quartz crystals have been brought to England under the impression of their being diamonds. A quartz crystal is usually a six-sided prism, with a six-sided pyramid at its end, a form which the diamond never assumes. Diamonds are eight-sided crystals, cubes, or. dodecahedrons..

Model of the Alps and the Plains of Lombardy. No. 21.

For a description of this model see "Catalogue of Models," p. 13..

Case of mineral specimens. No. 23.

Several remarkably fine mineral specimens, too large to be exhibited elsewhere, are here grouped together. Descriptions of these will be found under their respective headings. (See Index.)

Specular iron ore from the Island of Ascension. No. 25.

A notice of the volcanic island of Ascension will be found in the "Catalogue of Rock Specimens," 3rd ed., p. 220. The formation of specular iron ore in volcanos probably results from the action of watery vapour on perchloride of iron; hydrochloric acid being set free, whilst peroxide of iron is deposited in a crystalline form. Reference to Wall-case 18 will show that specular iron ore is by no means an unfrequent volcanic product..

Model of surface-workings of a Newcastle coal-pit. No. 26.

Presented by Mr. John Wales.

This model, the several parts of which are lettered, represents the arrangements used at a North of England colliery, for raising, screening, and loading the coals. From the face of the workings in the pit, the coal is brought in tubs, or wagons (0) which are placed on cages (D), and raised to the surface by the winding engine (A), which, with its two boilers (B), occupies a prominent position in the upper part of the model. Arrived at the top of the pit (C), the tuba (0) are placed in the teaming cradles (F), and the coals discharged upon the screens (I, I), the large coal passing directly into the chaldron wagons (H), while the small coal passes into the box (K), whence it is transferred to the small-coal screen (L) by which it is sorted into the three sizes, nut, seconds, and duff, discharged through the shoots marked respectively M, N, O.

In the same case is a model of cages used at Cowden Colliery, Dalkeith, presented by His Grace the Duke of Buccleuch and Queensberry, K.G., &c..

Models of the machinery for loading coal. No. 26. (Underneath).

Presented by Messrs. Vivian and Sons, Tai-bath, Glamorganshire.

It will be observed that in one instance the waggon on the rails runs on to a stage, which is lowered into the vessel's hold, when it is opened at the bottom, and the large coal quietly deposited in its place, the stage being returned, to its original position by counterbalance weights. The second model is similar in general principle, but here a box slung at the end of a crane is employed instead of the sliding stage..

Model of Holmbush Mine

by Mr. T. B. Jordan. No. 27.

In this model of Holmbush mine, near Callington, in East Cornwall, the excavations are represented by solid modelling, whilst the surrounding country below the adit-level is supposed to be removed, and hence appears as space. By this novel principle of modelling, for which a prize medal was awarded at the International'Exhibi-tion, the direction of the lodes and the details of the underground workings are distinctly seen, whilst the difference in the mineral contents of the veins is represented by a system of colouring, explained by a label attached to the model.

In 1863 Holmbush mine produced 1,048 tons of copper ore and 416 tons of lead ore. The workings are, however, now abandoned. A fine sample of the copper pyrites is placed beneath the model..

Model of Landslip at Axmouth. No. 28

At Christmas 1839, this great landslip took place. The model is constructed on the scale of 120 feet to an inch, and it represents a mile and a quarter of the country over which the subsidence took place. The length of the great chasm caused by this subsidence was 1,000 yards, the breadth 300 yards, and the depth varied from 130 feet to 210 feet. Twenty-two acres were sunk in the chasm. The Rev. W. 1). Conybeare thus describes the phenomenon :—

" On the morning of Tuesday the 24th, about three o'clock a.m., the family of Mr. Chapple, who occupied the farm of Dowlands, about half a mile from the commencement of the disturbances which ensued, was alarmed by a violent crashing noise; but nothing farther was observed through that day. On the following night, however, about the same hour, some labourers of Mr. Chapple, the tenants of cottages built among the ruins of the adjoining under-cliff, hurried to the farm with the information that fissures were opening in the ground around, and the walls of their tenements rending and sinking. Through the course of the day following (Christmas) a great subsidence took place through the fields ranging above Bendon Undercliff, forming a deep chasm, or rather ravine, extending nearly three-quarters of a mile in length, with a depth of from 100 to 150 feet, and a breadth exceeding 80 yards. Between this and the former face of the undereliff extends a long strip exhibiting fragments of turnip fields, and separated from the tract to which they once belonged by the deep intervening gulf, of which the bottom is constituted by fragments of the original surface, thrown together in the wildest confusion of inclined terraces and columnar masses, intersected by deep fissures, so as to render the ground nearly impassable. The insulated strip of fields also which has been mentioned is greatly rent and shattered. The whole of the traot which has been subjected to these violent disturbances must be estimated on the most moderate computation as exceeding three-quarters of a mile in length by 400 feet."

The tract of downs ranging along the coast is here capped by a stratum of chalk; this rests on a series of beds of consolidated sandstone, alternating with seams of that variety of flint called chert; beneath these more than 100 feet of loose sand, locally (from an obvious etymology) termed fox mould. This bed was the principal cause of the disturbance. It imbibes all the moisture falling on the surface, and as it rests upon retentive beds of clay, this water softens and wears away the fox mould, so as to render it incapable of supporting the weight of the superincumbent mass. The support being withdrawn, or proving insufficient, it is easy to conceive that cracks would from time to time be formed, and the undermined portions of the superstrata precipitated into the hollows prepared beneath them. (See Extraordinary Landslip and great Convulsion of the Coast of Culverhole Point, near Axmouth.. By the Rev. W. D. Conybeare. The Edinburgh New Philosophical Yournal, 1840.)

Model of peat moss in Auchengray Estate, Lanarkshire

By Thomas Gibb. No. 29.

This model of a peat moss, which slipped on the 12th and 15th August 1861, is accompanied by a descriptive label, affording sufficient explanation, which it is unnecessary to repeat here..

Model or part of the lead mining district of Alston Moor, Cumberland. No. 30.

This model, which was constructed by Mr. T. Sopwith, represents part of the mining district adjoining the river Nent. It exhibits the thickness and inclination of the strata of limestones, hazels (or sandstones), and argillaceous beds. In the front of the model is shown the celebrated "Nent-force Level." This work was projected in 1775, by Smeaton, and being judiciously carried out, it has been of the greatest advantage to the district. "Nents-berry engine shaft, represented on the model, is sunk down to Nent-force Level, 3i miles from the entrance. The whole of this distance, which was then navigable in boats, was surveyed by the author in 1826; it has since been continued, as shown in the model, on the top of the stratum of limestone called the Scar limestone. The usual mode of entrance to the lead mines of Alston is by means of adits or water levels, made sufficiently large for a horse to travel in. The entrance or level mouth of Nentsberry greens mine is shown on the model, and the several rises by which access is gained to the veins of ore in the great limestone."—(Sopwith.)

The mineral veins are seen on the sides of this model descending in nearly a vertical direction through the various strata. It will be observed that those layers are not opposite each other on either side of the vein. The cause producing the fissure in which the mineral matter has been deposited has occasioned the subsidence of all the strata on one side of the lode. Hence the mineral vein may have limestone on one side and sandstone on the other, or sandstone and clay may be opposite. It has been observed that the metalliferous character of the vein is in a great measure dependent upon the arrangement of the strata on either side of the lode. In this district the lead is usually found in the limestone, and when limestone forms both cheeks or sides of the vein it is generally there the most productive.

Old Carrs crop-vein in the model has, to use the miners' phrase, thrown down the strata 25 fathoms, whereas at Wellgill crop-vein the amount of vertical disturbance is only 3 fathoms. The great limestone is 91 fathoms thick, consequently it follows that the last-named vein has limestone sides for 61 fathoms (39 feet.)

Model of the workings. Of the Clunes and Port Philip Mining Companies, Victoria, Australia. No. 31.

The raising and crushing of the quartz, and the extraction of the gold, are represented in this model, which, however, requires no detailed explanation, since each portion is furnished with a number referring to an explanatory key which accompanies the model.

In the case beneath are placed some samples of gold-bearing quartz and "wash-dirt," from Australia, together with a model illustrating the Australian mode of timbering shafts. With these will be found a working model, by Mr. J. B. Jordan, of a horizontal high-pressure engine, furnished with a pair of fly wheels..

Model of a mining district of Cornwall, No. 32. See p. 91.

Model of steel works

Pres. by Naylor, Vickers, and Co. No. 33.

This model is intended to represent the arrangement for melting and casting steel, and for rolling it into bars, &o. A collection of steel will be found on the wall of the MODEL Room. (See p. 113.)

Model of lead-fume condenser at Wanlock Head Works. No. 34

The fumes are conveyed from the flues into a double-chambered condenser, where the lead is separated by passing through showers of water; the purified smoke escaping through a tall chimney, while the water is collected in a reservoir where the lead is deposited..

Water barometer

This instrument has recently been erected at the northern end of the room, near Wall-case 29. From the ordinary mercurial barometer it differs only in the substitution of a column of water for one of quicksilver; but since water is, bulk for bulk, about 13½ times lighter than quicksilver, it is obvious that the column of water necessary to counterbalance the atmospheric pressure must be 13½ times longer than that used in our ordinary instruments; thus, the mean height of the mercurial barometer being about 30 inches, that of the water barometer will be upwards of 33 feet. Apart from other objections, the manifest inconvenience of so unwieldly an instrument forbids its general adoption, but the extreme sensibility of its indications gives it considerable scientific interest; the column of water being sensibly affected by variations in aerial pressure too slight to produce any perceptible effect on the mercurial barometer.

Some years back, an instrument similar in principle, but different in construction, was erected, by the late Professor Daniell, in the Royal Society's Hall. In the instrument before us, which was constructed by Mr. J. B. Jordan on the plan suggested by Mr. Bird of Birmingham, the glass tube forming the upper part of the barometer is alone exposed, the metal tubing constituting the lower portion being carried downwards to the basement of the building, where it terminates in a cistern of water, the surface of which is covered with a stratum of mineral oil to prevent evaporation of the liquid and absorption of air. For constructive details the visitor is referred to the Philosophical Mag., vol. xxx. p. 349..

Model of a portion of the Undercliff, Isle of Wight

by Capt. Boscawen Ibbetson, K.R.E. No. 35.

This model represents a portion of the south side of the Isle of Wight, extending from Bonchurch to Sandown Bay. The chalk, which stretches across the island from east to west, forming the downs or undulating tracts of high ground, is seen to rest immediately upon the upper greensand, which is separated from the lower greensand by a band of gault. The upper greensand slipping over the surface of the gault clay has given rise to the romantic scenery of the Undercliff. For farther information, see "The Geology of the Isle of Wight," by H. W. Bristow, F.R.S., published in the "Memoirs of the Geological Survey."

Models of water wheels at the Devon Great Consolidated Mines

Presented by the Company. No. 35.

These mines consist of Huel ^[2] Maria, Had Fanny, Huel Anna Maria, Huel Josiah, and Huel Emma. They are situated on one of the banks of the river Tamar, near Tavistock, among, most beautifully-wooded hills. These wheels are worked by a stream of water taken from the river at a higher level. One set of wheels is employed in draining the mine, and another for sending water over the hill to supply the dressing floor of the mine. There has rarely been any mine adventure attended with such success as this. The total quantity of ore raised from the commencement in 1845 to the year 1866 amounted to 469,154 tons, of the value of 2,592,790l. This amount of ore yielded 33,116 tons of metallic copper.

Agates

Case No. 38.

Each specimen in this case being fully labelled, any detailed description is unnecessary. Samples are shown of the amygdaloidal melaphyre in which the German agates occur. It is probable that the disengagement of gas or steam produced pear-shaped cavities in the igneous rock when in a fluid condition, and that these hollows have been since filled, partially or entirely, by silica and-other substances deposited upon the walls of the cavities from solution in the water circulating through the rock..

Ornamental iron castings

Case 39.

Some fine examples of the use of iron in art manufacture, and for the reproduction, in a durable material, of works of high art, are exhibited. Such productions are coloured either by the application of a resinous paint or by a process of bronzing, which may be effected by the application of chloride of platinum, of the salts of copper and iron, and by other means, one of these being the deposition of thin coats of copper or brass by the electrotype process.

Berlin Cast Iron.—Some fine examples of the delicate iron castings of Prussia are in this case. At the time when the final struggle commenced between Prussia and Napoleon, the patriotism of the Prussian ladies was particularly conspicuous. With the noblest generosity they sent their jewels and trinkets to the Royal Treasury, to assist in furnishing funds for the expenses of the campaign. Rings, crosses, and other ornaments of cast iron were given in return to all who made this sacrifice. They bore the inscription, Gold für Eisen (gold for iron). Such Spartan jewels are, to this day, much treasured by the possessors and their families.—(Handbook of Northern Germany.) This led to the production of ornaments far more delicate than anything which had theretofore been, manufactured; and these becoming known and admired. in every part of Europe, an extensive trade in, them speedily arose, and has been maintained.

The Castings intended for use in Bookbinding, the Cast Iron Fan, Necklace, and Bracelets, from the iron works of the Count de Stolberg-Wernigerode, at Ilsenburg, Hartz Mountains (Magdeburg), are fine examples of this manufacture.

The large ornamental casting, with the sand attached, as it was taken from the mould, shows the perfection to which the processes have been brought. It has been thought that much of the beauty of these castings depends upon the sand employed in forming the moulds. Hence the sand collected about this casting has been carefully analysed in the metallurgical laboratory. It was found to consist of:—

Silica	79.02
Alumina	131.2
Protoxide of iron	2.40
Lime	trace
Magnesia	0.71
Potash	4.58

Whitworth' s Screws and Plate may be regarded as perfect examples of the production of true surfaces. When the two iron planes are brought together the upper one floats on a film of air, and when this is pressed out the cohesive force of the two surfaces is very great; this may be regarded as a proof of the correctness with which these surfaces have been formed.

The screws and the gauges were prepared with a view to the introduction of a system of standard screws and gauges..

Models of the salt mines of Hallein and Hallstadt, in the Salzburg Alps. Nos. 40 and 44.

They are opened in deposits of a very irregular form belonging to the secondary series, and in which the rock salt is mingled with clay and gypsum. The principle of working is to introduce fresh water into excavations prepared for the purpose, where it gradually dissolves the salt, leaving the clay and gypsum behind; the brine is then conducted by lower galleries to the outside of the mountain, and runs in pipes to the spot where the evaporation works are situated.

A third model, representing the salt mines of Anssee, will be found in the upper gallery..

Swedish iron and steel

Case No. 42.

It has already been mentioned at p. 84 that iron of a very superior quality, much valued for steel manufacture, is produced. from the iron ores of Sweden. These consist chiefly of the magnetic and red oxides, which are classed together as "mountain ores," to distinguish them from the brown oxides, which occur in the shape of lake- and bog-ores, and yield an inferior kind of iron employed chiefly for castings. The mountain-ores are calcined, usually in kilns heated by the waste gases from the blast furnace, and are smelted exclusively with charcoal. It is to the employment of this fuel, and to the freedom of the ores from phosphorus. that the Swedish iron owes its superiority. The greater part of the pig iron is converted into malleable iron in refineries, or hearths, heated with charcoal. At Dannemora the ancient Walloon process is still employed, but at most other works it has been displaced by the so-called "Lancashire method," introduced from South Wales. In some of the Swedish works puddling is practised to a certain extent, and the Bessemer process has also been introduced..

Chinese enamels, glass, &c.

Case No. 43.

The enamels and glass have been already noticed at p. 72. With these are associated a few illustrations of oriental metallurgy, and some miscellaneous objects not yet finally arranged. The carvings in jade are noticed at p. 145..

Flint implements, &c. mosaics

Case No. 46.

Associated with the bones of many of the extinct mammalia of the post-pleiocene era there have been found within the last few years great numbers of flint implements, bearing undoubted proofs of human workmanship. The French antiquary, M. Boucher de Perthes, was the first to direct attention to the occurrence of flint "hatchets" at considerable depths in the sands and gravels of the valley of the Somme. Some of these worked flints from Abbeville and Amiens are here exhibited, and with them are other flint implements from widely separated localities. These rudely chipped flints, occurring in the drift-gravels, are to be distinguished from the more highly finished celts, which, in most cases, bear evidence of having been carefully ground and polished : such stone weapons, by no means always of flint, are much more recent than the worked flints from the drift, being referable to the prehistoric era, known to archeologists as the polished or newer stone age.

For comparison with these ancient flints and colts, and to explain their probable use, are placed in the same group examples of the rude stone implements used by certain savage tribes at the present day. A few flint arrow-beads, prepared to deceive collectors, are also placed by the side of the genuine relics.

The collection illustrating the manufacture of mosaics, occupying the opposite side of the case, has been noticed in connexion with the vitreous series, see p. 72..

Modern flint glass

Case No. 47. Described at p. 68..

Slab from the bone-cavern of Les Eyzies. No. 50

Presented by M. Lartet and the late H. Christy, Esq., F.O.B.

This slab of osseous breccia was obtained, by the donors, from the floor of the bone cavern of Les Eyzies, in the valley of the B elms, a tributary to the Vezere, in Dordogne. The bones are chiefly those of the reindeer, and are in most cases fractured, having probably been broken for the extraction of the marrow. These bones are associated with great numbers of worked flints, rolled pebbles, and fragments of foreign rocks, the whole being cemented together by stalagmitic carbonate of lime. The most interesting relics of human workmanship in these deposits are certain rudely-engraved pieces of bone and plates of schistose rock, which are undoubtedly the earliest known specimens of the engraver's art. In the block before us there has been found a small bone needle, and a human tooth was detected in a similar slab sent to Vienna.

The bone deposits of Dordogne are referable to a remote era, when the use of metal was apparently unknown,—an era posterior to that of the mammoth, and characterized by the presence of the reindeer in certain southern districts where it has not been found during the historic period..

Model of a portion of the Isle Of Wight

by Capt. Boscawen Ibbetson, K.R.E. No. 49.

This model represents the coast of the Isle of Wight between Sandown Bay and Whitecliff Bay. The almost vertical position of the chalk is well indicated by the layers of dark flints occurring _.in the upper chalk. The tertiary beds which rest on this highly inclined chalk are, in ascending order, the plastic clay or Woolwich and Reading series, the London clay, the various subdivisions of the Bagshot beds, the Headon and Osborne series, and the Bem-bridge beds. (See Mr. Bristow's Memoir on "The Geology of the Isle of Wight," referred to at p. 129)..

Sundry specimens

Flemish Monumental Brass. Near Case 37, on eastern side of Museum.

This brass forms part of the mixed-metal series exhibited. It is of Lodewyc Cortewille, of Cortewille, near Liege, who died in 1504, and of his wife Colyne van Castre, who died 1496. The analysis made in this establishment shows its composition to be—

Copper, 64.0; Zinc, 29.5; Lead, 3.5; Tin, 3.0.

A casting in aluminium (p. 121) of Venus of Nilo, by N. Morin, stands on a pedestal on the eastern side, between wall-cases 52 and 53. On the shelves beneath are some masses of hmmatite (p. 102), and a specimen of cyano-nitride of titanium (p. 115). Near the Head of Melpomene, No. 51, are several querns or ancient hand-mills used for grinding corn. Most of these being formed of a siliceous conglomerate or "pudding-stone," a rough surface is constantly maintained by the unequal wear of the flint pebbles and the cementing substance.

An ancient coat of mail and a Greek tripod in bronze will be found on the western side of the room; and at the southern end, near the case of Venetian glass, No. 55, is an apparatus for exhibiting some of the chromatic phenomena developed by the analysis of light, which having first undergone the peculiar physical change called polarization, has then been transmitted through thin plates of a doubly refracting mineral.

A fine specimen of fibrous malachite, from New South Wales, and a series of recently-erupted lavas and scorice from Santorin, are placed provisionally on the model of the water-wheels, No. 35.

Horse-Shoe Case

Non-metallic minerals and their applications. Commencing at the right hand or eastern side.

Case A.—Carbon

Diamonds.—From the high refracting power of the diamond, Sir Isaac Newton conjectured that this beautiful gem might be a combustible body. In the heat of the oxyhydrogen flame, and in oxygen gas the diamond has been burned, producing only carbonic acid; and by the electric arc it has been converted into coke and graphite, thus proving that this hard transparent body is only carbon in a peculiar form.

Diamonds are found naturally crystallized, the forms always being related to the cube; the faces are usually rounded as seen in the crystals exhibited. Diamonds have been, through all time, discovered in the East Indies, especially in the kingdoms of Golconda and of Visapour, but the largest supply is at present obtained from the mines of Brazil, where they occur chiefly in a deposit called cascalho, consisting principally of fragments of quartz and ferruginous sand : a sample of this cascalho is shown.

Many of the largest known diamonds which have acquired historic interest are here represented by models, among which those of the celebrated Koh-i-noor claim especial attention. This diamond is, according to Indian traditions, more than 4,000 years old, having been found in the mines of the south of India in the days of the great war celebrated in the heroic poem, the Mahábhárata, and was worn by one of the warriors who was slain on that occasion. The Rajah of Ujayin, 50 B.C., is said to have had possession of this gem, and it remained with his successors until it fell into the hands of the Mohammedan conquerors of India.

In 1665 this jewel was examined by Tavernier in the cabinet at Delhi, and in 1739 Nadir Shah, on his occupation of Delhi, obtained possession of it. After his death the diamond, which he had wrested from the unfortunate representative of the house of Timur, became the property of Ahmed Shah, the founder of the Abdali dynasty of Kabul, who probably took it from Shahrikh, the young son of Nadir Shah. The jewel descended to the successors of Ahmed Shah, and was worn by Shah Shuja on his arm. When Shah Shuja was driven from Kabul he became the prisoner of Runjet Sing, who compelled the fugitive monarch, in 1813, to resign the precious gem for, it is said, a lakh and twenty-five thousand rupees, above 12,000l. sterling. Runjet wore the diamond as an armlet on all great occasions; after his death it was worn by Rhurreuk Shing. and Shu Shing. After the murder of the latter it remained in the Lahore treasury until the supercession of Dhulip Sing, and the annexation of the Punjaub by the British government, when the civil authorities took possession of the Lahore treasury, under the stipulations previously made that all the property of the State should be confiscated to the East India Company, and that the Koh-i-noor should be given to the Queen of England. In order to bring out its lustre and remove some flaws, this gem was re-cut after the Great Exhibition of 1851, under the direction of Messrs. Garrard, and since the cutting its beauty has been greatly enhanced. In this Case will also be found models of the following diamonds, the weights and approximate values of which are expressed on the accompanying labels:—The Rajah of Mattan's; the Star of the South; the Mogul; the Regent, Pitt, or Orleans; the Orloff, or Russian; the Tuscan; the Florentine, or Austrian; the Hope; the Dresden's; the Nassuck; the Pigot; the Shah; the Sancy; the Eugénie; the Polar Star; the Cumberland; Mr. Dresden's; the engraved Persian; and a diamond said to have been worn by Napoleon in the hilt of his sword.

The impure variety of diamond called bort or boort, which occurs usually in small spherical nodules, having a radiated internal structure, is employed, in the state of powder, as a grinding and polishing agent; and the dark-coloured non.-crystalline substance called "carbon" or carbonado receives a similar application. The latter is a peculiar form of carbon, discovered in the diamond gravels of Brazil in 1842, and appears to furnish a transition from ordinary diamond to the next species—graphite.

Plumbago, Graphite, Black Lead.—This mineral, which is composed of carbon and a variable small quantity of iron, occurs in beds and imbedded masses, in granite, slate, and crystalline limestone, and in nodules in greenstone. It is occasionally found crystallized in thin six-sided plates; and a similar form is assumed by the artificial graphite or, "Kish" formed during certain metallurgical operations.

The plumbago from Borrowdale in Cumberland has long been celebrated for its fine quality, but the supply is very irregular, the mineral being found only in detached pieces, called, according to' their size, sops or bellies. Some years since a very large quantity, of plumbago was obtained from Borrowdale; this has been stored by the proprietors, and sold in small parcels from time to time.' The mine has not been worked for several years : it was examined, by some skilled miners since the cessation of the work, and their opinions were not such as would lead us to believe that any large quantity of black lead would be discovered by any extension of the workings.

The application of plumbago to the manufacture of crucibles having been already noticed, it remains only to mention its use in the preparation of black lead pencils, as illustrated in this case.

Pencils are of three qualities,—drawing pencils, prepared pencils, and composition pencils. Pencils of the first quality are made of pure Cumberland plumbago, which costs about 168l. per cwt. They are made by sawing the "lead" into pieces, and inserting them in the cedar. A pound of plumbago will produce about 18 or 20 dozen of pencils.

Pencils of the second quality are manufactured out of the sawings or dust of pure black lead, and the small pieces which could not be cut into pieces of sufficient length; this is mixed with a certain quantity of antimony. The antimony is frequently in large excess above the black lead, the former costing only 26s. the cwt., the latter 100l. The third quality of pencil is made with Mexican or Spanish plumbago and antimony, sulphur being added to produce the blacker pencils.

Brocicedon's Patent.—The smaller pieces of the Cumberland plumbago, which are too small to be cut into slices for pencils, but, are yet of very fine quality, are ground to an impalpable powder, which is subjected to enormous pressure, imparted by means of a screw press. The result of this is that the plumbago powder is rendered perfectly coherent. From the blocks thus formed, some of which are shown, slices are sawn, from which pencils of the best quality, and entirely free from grit, are formed. The fracture of this compressed plumbago precisely resembles that of, the natural graphite..

Case B.—Carbon, Hydro-carbons, &c.

Coal.—The varieties of coal, occupying the greater part of this case, form a regular series, commencing with the non-bituminous stone-coal or anthracite, and passing thence through the ordinary bituminous coals to the recently formed lignite or brown coal, in which the original structure of the wood is frequently retained. The probable mode in which coal has been formed is noticed at p. 152.

Anthracite always contains a large quantity of carbon, and but a small proportion of volatile constituents; as the anthracites become softer they are distinguished as free-burning coals, and these may pass into the ordinary bituminous varieties, as in the South Wales coal-field.

The "crystallized" coal exhibits a very peculiar structure, known as cone-in-cone; and in the peacock coal, provincially called moontons, we have a remarkable example of the influence of surface arrangement in producing colour.

Cannel coal is usually regarded as a hard, compact variety of bituminous coal. It burns readily without melting, with a clear yellow flame, and it has been used as a substitute for candles, whence its name, candle, or, in local patois, cannel coal. Large quantities are raised near Wigan in Lancahire, and at Lesmahago, about twenty miles from Glasgow, where it is made into inkstands and other ornamental articles.

The Albertite from Nova Scotia appears to be an asphaltic variety of cannel, but its right to be called a "coal"is perhaps questionable.

Lignite or brown coal, which frequently retains the original texture of wood, usually occurs in deposits of tertiary age. In Germany, lignite is extensively worked, but in this country it is raised only at Bovey Tracey, in Devonshire, where it occurs in beds of meiocene age. The value of lignite as a fuel is far inferior to that of ordinary pit-coal.

Jet appears to be a compact variety of lignite. At Whitby the jet occurs in the upper-lias shale, from which it is collected with great labour. It is also found on the shore, being frequently thrown up after storms. Jet is the gagates of Pliny, a name derived from the river Gagas in Syria.

With the coals are introduced a few minerals, or rather rock-substances, which, although differing essentially from coal, nevertheless possess considerable economic value. Or these the most interesting is the Torbane Hill mineral, or "Bog Head cannel," found in the coal-measures of Linlithgowshire. From this substance, which is well known as having been the cause of considerable litigation, arc obtained, by distillation at a low temperature, certain hydro-carbons highly valued, partly for illuminating purposes, and partly as lubricating agents.

The so-called Kimeridge coal is a bituminous shale occurring in the Kimeridge clay of Dorsetshire. When heated to redness in the open air the organic matter is slowly burned away with a smoky flame, and a bulky ash remains, consisting principally of alumina, the quantity of which is so large that some of the shale has been used as a source of alum, and a former possessor of the property erected works for this purpose. If, instead of being heated to redness in the open air, the shale be heated in a close vessel, a variety of valuable gaseous or liquid compounds may be distilled off. Sinai' circular discs of this Kimeridge shale are frequently found in the Isle of Purbeck, and from their supposed use pass under the name of Kimeridge coal money, but it is more probable that they are simply the refuse-pieces from which rings or armlets have been turned.

Among the carbonaceous minerals in this case will be found a small group of artificial products, including some peculiar varieties of coke, and some samples of the so-called "graphite" found lining the interior of gas retorts.

The remainder of this section is occupied by certain organic compounds, which require no very special description. Hatchettine or mineral tallow is a hydro-carbon occurring in the nodules of clay ironstone from the South Wales coal-field; and ozokerite or mineral wax is a substance of very similar composition, found in considerable quantity in Moldavia, where it is applied by the peasants to a variety of purposes. Closely related to these are the substances grouped together under the general name of bitumen or mineral pitch,. The compact variety called asphalt is represented by specimens from the mountain limestone of this country, and from the celebrated Pitch Lake of Trinidad. This lake is one and a half miles in circumference; the bitumen is solid and cold near the shores, but gradually increases in temperature and softness towards the centre, where it is boiling. The solidified bitumen appears as if it had cooled as the surface boiled in large bubbles. The ascent to the lake from the sea, a distance of three-quarters of a mile, is covered with a hardened pitch, on which trees and vegetables flourish; and about Point la Braye the masses of pitch look like black rocks among the foliage; the lake is underlaid by a bed of mineral coal.—(Manross, quoted by Dana.)

The elaterite or mineral caoutchouc is a soft elastic variety of bitumen having a peculiar odour, and occurring in the carboniferous limestone of Derbyshire, where it was first observed, at the forsaken lead mine of Odin, by Dr. Lister, in 1673. Passing over a small group of mineral resins, found chiefly in deposits of lignite, the only other mineral which need be noticed in this section is the well-known substance amber.

The vegetable origin of amber is now fully ascertained. This is inferred both from its native situation with coal, or fossil wood, and from the occurrence of insects encased in it. Of these insects some appear evidently to have struggled after being entangled in the then viscous fluid, and occasionally a leg or a wing is found some distance from the body, which had been detached in the effort to escape. Goppert has named the tree yielding it Pinites succinifer (Dana). The principal supply of amber is obtained from the Prussian coast of the Baltic.

Such are the examples of natural substances belonging to the carbon group, commencing with the most brilliant of gems, passing through all the varieties of coal, and terminating with another substance used for ornament, amber.

The coal-fields of England are the most important in the world, the production from British collieries during the year 1865 having reached the prodigious amount of 98,000,000 tons..

Case C.—Sulphur

Sulphur is one of the most widely diffused chemical elements in the vast economy of nature. It occurs chiefly in volcanic districts; Sicily and the neighbouring volcanic islands, and the Solfatara, near Naples, being the great depositories from which it is obtained. As native sulphur is usually contaminated with earthy matters, it is purified by distillation. Sulphur is also largely extracted from iron pyrites (p. 101), a bisulphide of iron, which yields a considerable proportion of free sulphur on simple distillation.

At ordinary temperatures sulphur exists as an opaque solid, S.C. 1.98. It melts at 226° Fah. to an amber-coloured liquid; if the temperature be then raised to about 400° Fah, it becomes dark brown, opaque, and so thick that the vessel containing it may be inverted without pouring out; but heated yet higher it again becomes thin and limpid. If the thick tenacious sulphur at 400° be suddenly cooled by immersion in a large quantity of water, it forms a soft and transparent mass of considerable elasticity. In this state it is used for receiving impressions of seals, &c.; after some time it changes into its ordinary state.

Th crystals of native sulphur, and those prepared by evaporation from solution at ordinary temperatures, are entirely distinct in form from the crystals which may be obtained by solidification from a state of fusion; and this difference in crystalline character is accompanied by a corresponding variation in density and other physical properties.

With the sulphur-group will be found a fine specimen of the closely-allied but much less widely-diffused element, selenium, as prepared from the deposits of the copper-smelting furnaces of Mansfeld (p. 104)..

Case D.—Salts of Sodium, Potassium, and Magnesium

A large specimen of crystallized sodium is exhibited in connexion with the aluminium-series on the opposite side of the room; and another specimen is placed here as representing the metallic base of a group of minerals which occupy a prominent position in this section. Of these salts of sodium, the most important is the chloride or common salt. The greater part of our culinary salt is manufactured from the brine springs of Cheshire and Worcestershire, which rise probably from beds of rock salt. The rock salt itself is largely worked at Northwich, in the valley of the Weaver, and near Belfast, in Ireland. A thick bed has recently been pierced at a considerable depth at Middlesbro'-on-Tees. The rock salt of Cheshire occurs in stratified deposits near the base of the New Red or Keuper Marls, associated with gypsum. Occasionally the salt is colourless and crystalline, but usually it is coloured to a greater or less extent by the presence of peroxide of iron. Although generally found in the New Red Sandstone, rock salt is by no means confined to this formation; the deposits, for example, of Wieliczka in Poland, and Volterra in Tuscany occurring in tertiary marls : from both these localities specimens are exhibited.

The curious hopper-shaped crystals of salt here shown result from the aggregation of a number of small cubes formed on the surface of the brine during evaporation.

The Greenland mineral called cryolite or ice-stone is a double fluoride of aluminium and sodium, which has been already noticed as a source of aluminium.

The few salts of soda, or oxide of sodium, here exhibited require no lengthened description. The _.deliquescent nitrate known as cubic nitre is employed as a source of nitric acid, and to a limited extent as a substitute for saltpetre while the borate of soda or borax, known in its crude state as tincal, is largely used for soldering, and for glazing pottery. From borax we pass to boracic acid, of which a small group of specimens is here introduced.

This acid, a compound of boron and oxygen, is obtained for the arts from the volcanic fumaroles of Tuscany. The first locality known was at Sasso, whence the name sassolin. The lagoons of Tuscany spread over a surface of about 30 miles, and clouds of vapour are constantly seen rising in large volumes among the mountains. As they are approached the earth appears to pour out boiling water, as if from volcanos of various sizes, the heat in the-immediate neighbourhood is intolerable, and the vapours suffocating; the vents for the vapour are termed soffloni. These hot vapours, which contain only a small proportion of boracic acid, are made to pass through water, by which the acid is absorbed. This weak solution gradually becomes more highly charged, as it is transferred from one lagoon to another, and, when sufficiently impregnated, the solution is evaporated by means of the steam from the springs. The specimens exhibited are from the works of the late Count Larderel, whose name deserves record as the founder of this branch of industry in Tuscany.

Among the salts of boracic acid may be noticed hayesine, a borate of lime occurring in white reniform masses, scattered over the dry plains of Iquique in Southern Peru, where it is called tiza.

Of the salts of potash only a small number occur native. The nitrate called nitre or saltpetre is of considerable value, being extensively employed in the manufacture of gunpowder. In the East Indies and in Ceylon a great number of nitriferous caverns exist, but the spontaneous generation of nitre in India, Egypt, Spain, and elsewhere is insufficient to supply the wants of the world, and a large quantity is therefore prepared artificially.

Nitrate of potash crystallizes in six-sided prisms, with four narrow and two broad faces, as may be well seen in the artificial crystals.

Alum is placed here as a salt containing potash and alumina in combination with sulphuric acid and water. Such at least is the composition of ordinary alum, but in other varieties the potash may be replaced by soda or other protoxides. Alum has long been manufactured on a large scale, from the alum slate or shale of Whitby. On roasting this- shale, the disseminated iron pyrites undergoes decomposition, a portion of its sulphur being converted into sulphuric acid, which forms a sulphate of iron and alumina, and on decomposing this by a salt of potash common alum is obtained. The shale in various stages of decomposition and some fine alum crystals are here shown.

The Hungarian alumstone is an altered trachytic rock, not only used as the source of a very pure alum, but also employed occasionally as a millstone.

Some peculiar minerals are exhibited from the recently developed salt deposits in the Zechstein of Stassfurt in Prussian Saxony.

In this section are also placed a few minerals containing magnesium, such as brucite and epsomite, accompanied by several specimens of the metal. Although magnesium was discovered by Sir H.

Davy in 1808, it is only by Mr. Anstadt's recent improvements in its manufacture that it has been obtained in quantity sufficient to render it of commercial importance. By the action of hydrochloric acid on carbonate of magnesia there is obtained a chloride of magnesium, from which the metal is reduced by the action of sodium..

Case E.—Salts of Baryta and Strontia

The very widely diffused mineral barytes or sulphate of baryta is frequently employed as a pigment, either alone or associated with white lead;'and for this purpose the mineral is raised in Derbyshire, the Isle of Arran, and other places. From its density barytes is commonly known as heavy spar; while the massive earthy varieties often pass under the name of cawk.

Witherite, a carbonate of baryta, named after Dr. Withering, occurs in remarkably fine crystals at Fallowfield mine, near Hex. ham, in Northumberland.

Carbonate of baryta combines with carbonate of lime, forming a, double salt, which, occurring in two distinct series of crystalline forms, gives rise to the two species baryto-calcite and alstonite.

The earth strontia, closely allied to baryta, occurs in the form of sulphate and carbonate. The sulphate called celestine, from the pale blue colour which it occasionally presents, occurs in fine crystals at Girgenti, in Sicily, associated with native sulphur; and in the neighbourhood of Bristol, in the, New Red Marl.

The carbonate known as strontianite is found in the lead mines of Strontian in Argyleshire, a locality which has given its name to the mineral.

The salts of strontia are remarkable for the red colour which they impart to flame, those-of baryta giving a green tint..

Case F.—Salts of Lime

Gypsum or Hydrous Sulphate of Lime.—In connexion with the case in the lower Hall, illustrating the applications of plaster of Paris, this salt of lime has been described (p. 34). The crystalline character of gypsum, or, as the transparent varieties are called, selenite, is well shown by the perfect crystals which not unfrequently Occur in deposits of clay and marl; a characteristic twin-form being seen in the fine arrow-head crystal from the celebrated quarries of Montmartre, near Paris. The beads and other objects of fibrous gypsum exhibit in a marked degree the pleasing lustre which has led to the name of satin spar; whilst the carving executed by Mr. Jordan's machinery illustrates the application of the variety called alabaster, described at p. 26. The waterless sulphate of lime, anhydrite, has been already noticed (p. 34).

Apatite or Phosphate of Lime.—In different varieties the composition of apatite varies, but it consists essentially of phosphate of lime associated either with a chloride or fluoride of calcium, or with both. This mineral is not unfrequently found in company with tin ores. The extensive use of phosphate of lime as a fertilizer gives considerable commercial value to the deposits of this mineral occurring in Spain, Nassau, Norway, and Canada. With these minerals are grouped a few other phosphatic substances applied to similar purposes. In the lias, greensand, and other secondary formations numerous coprolites and phosphatic nodules occur; and in several of the tertiary strata of the eastern counties are found abundant mammalian and other animal remains : by the action of sulphuric acid these are converted into super-phosphate of lime, in which form they are largely employed for manure. Valuable phosphatic deposits have recently been discovered in North Wales. The well-known Peruvian guano and the West Indian sombrerite find a place in this group..

Case G.—Fluospar

The species fluor spar is here represented by a number of specimens, not less attractive by their variety of colour than by their beauty of crystalline form. The mineral, which is a fluoride of calcium, containing fluorine 48.7, calcium 51.3, is found abundantly in nearly all our mining districts, especially in Cumberland and Derbyshire, Devon and Cornwall. Its chief uses are as a flux in certain metallurgical operations, and as a source of hydrofluoric acid.

By acting upon powdered fluor spar with sulphuric acid, hydrofluoric acid is liberated, and may be used to etch glass, which it attacks with great energy. A fine etching executed in this manner will be found in Case 52, p. 67.

The violet-blue variety of fluor known commonly as "blue John," is used in the manufacture of tazze, as shown in this case, and of vases as exhibited in the Hall.

Being slightly soluble in water containing bi-carbonate of lime in solution, this mineral often disappears from the lodes in which it previously existed, leaving moulds of its form filled with other minerals, or coated by them. See such examples in Wall-case 34..

Case H.— Calcite

Some idea of the great variety of forms assumed by this widely distributed mineral will be gained from the numerous crystallized specimens grouped together in this section. On fracture, the crystals of calcite split with the utmost ease into regular six-sided solids called rhombohedrons; and it was indeed in this species that the property of cleavage in minerals was first observed. Calcareous spar is a carbonate of lime, containing, in a state of purity, carbonic acid, 44; lime, 56; but it often contains impurities upon which depend the colours assumed by the mineral.

The highly transparent varieties are termed Iceland spar, the finest specimens being obtained in Iceland. This crystal is remarkable for its double refraction, the phenomena of which are well shown in the specimens exhibited. The power of refracting light doubly is, however, enjoyed in a greater or less degree by all crystalline minerals, except those belonging to the cubic system..

Case I.—Carbonate of lime continued

Many of the massive forms of carbonate of lime having been already described in connexion with the marbles (p. 22) and limestones (p. 28) in the Hall, it only remains to notice among the marbles here exhibited—the giallo antico, or yellow marble of Sienna, generally known as Sienna marble; the onyx marble, from Algeria, a stalagmitic form similar to the "alabaster" of the ancients; and the fire marble, or lumachella, from the lead mines of Bleiberg, in Carinthia, remarkable for the brilliant iridescence of its fossils.

The Derbyshire inlaid marble work in imitation of Florentine mosaic is sufficiently explained by the descriptive labels attached.

The Fontainebleau sandstone or limestone is an aggregate of rhombohedrons of carbonate of lime, containing a large quantity of sand mechanically mingled.

In connexion with the varieties of carbonate of lime will be found some interesting examples of the production of pearls on the shell by the artificial process of introducing some body producing much irritation to the animal.

A very distinct physical condition of carbonate of lime is presented in the mineral called aragonite, from having been first discovered at Aragon in Spain. In addition to the fine rhombic crystals may be noticed the coral-like stalagmitic forms occurring chiefly in the iron mines of Styria, and known as flos ferri, or "flower of iron."

Carbonate of lime frequently contains a variable amount of carbonate of magnesia, and when the two compounds occur united in nearly equivalent proportions, they form the species dolomite, already described among the building stones (p. 31). As the proportion of magnesia increases, the species passes into magnesite, or carbonate of magnesia..

Case J.—Quartz

Occurring under a greater variety of aspects than any other member of the mineral kingdom, the species quartz necessarily claims a somewhat large amount of space. Pure quartz consists simply of silica, or oxide of silicon, in the insoluble state; that is, it is not soluble in solution of potash. The mineral crystallizes in forms belonging to the rhombohedral system, and is sufficiently hard to scratch glass with facility.

Rock crystal is a pure transparent variety, frequently enclosing rutile, chlorite, various fluids, &c. Small brilliant crystals are often locally termed "diamonds; " such, for example, are the so-called Cornish diamonds, Bristol diamonds, Ste. Under the name of "white stone," the mineral is occasionally employed in jewellery, those crystals being valued which contain slender prisms of rutile, or oxide of titanium, known to the jeweller as polies d'amour, or love's arrows. A more useful application of rock crystal is the formation of "pebble" lenses for spectacles.

Smoky quartz is a variety presenting a brownish tint, the term morion, being applied when the colour becomes intense. The transparent brown and yellow crystals form the well-known Scotch stone called from its locality cairngorm; whilst the bright yellow varieties are distinguished as caring or false topaz. Amethyst is another form of crystallized quartz, usually presenting a purple colour, due to the presence of either oxide of manganese or oxide of iron. Amethysts of the finest quality are found in India, Ceylon, Persia, and Siberia.

The pink colour of rose quartz is probably referable to a slight admixture of oxide of manganese; and in the ferruginous quartz, or Eisenkiesel, the mineral is deeply coloured, and usually rendered opaque by the presence of hydrous peroxide of iron. Thin fibres of asbestos (p. 145) penetrating the quartz give rise to the remarkable lustre of the cat's-eye, a mineral obtained chiefly from Ceylon; whilst the gold-spangled appearance of the aventurine is probably due to the presence of minute scales of mica. The aventurine glass has been alluded to at p. 70. The remaining varieties of quartz here exhibited do not appear to need any description..

Case K.—Chalcedony and Jasper

In this section we are introduced to the chalcedonic and jaspery varieties of quartz. Chalcedony is a translucent variety, of a waxlike appearance, occurring chiefly in stalactitic forms. It has been regarded as a mixture of ordinary quartz with opal, or soluble silica. Many of our most beautiful siliceous minerals are simply coloured varieties of chalcedony; oxide of nickel, for example, producing the apple-green tint of the chrysoprase, while peroxide of iron gives rise to the bright red tint of carnelian, and the deep reddish brown colour of sard. The beauty of the varied forms of agate depends chiefly on the alternation of different varieties of chalcedony. The formation of agates is fully illustrated in a case on the opposite side of the room, and is briefly described at p. 129. Most of the agates of commerce are coloured by artificial processes, such as boiling them in oil, and subsequently treating them with sulphuric acid; the oil is absorbed into the more porous layers, and then carbonized by the action of the acid; thus the artificial dark-coloured varieties are formed. By first boiling agates in solution of proto-sulphate of iron, and then exposing them to heat, by which peroxide of iron is formed, the red varieties are produced.

In the moss agate and Mocha stone the dendritic or moss-like delineations of an opaque brownish yellow or green colour are mostly due to oxide of manganese or of iron. Regular alternations of light and dark coloured chalcedony are presented in the onyx, and on this depends its value for cameo work : when the layers consist of card juxtaposed with strata of white chalcedony, the stone is called a sardonyx.

Another group of siliceous minerals is formed by the jaspery varieties of quartz : when the colours are in stripes it is called ribbon jasper, of which some fine Siberian specimens will be found at the southern end of the room. In the Egyptian jasper, which occurs usually in the form of rolled pebbles, the brown colours are disposed in concentric zones. Heliotrope, or blood-stone, is a jasper of a deep green colour, interspersed with blood-red spots, found in Silesia, Iceland, and the Island of Rum, Scotland..

Case L.—Silica, amorphous and hydrous

The quartz-family is here brought to a close by a few minerals, for the most part less attractive than those already noticed. Ordinary sandstone has been described in connexion with the building stones (p. 28). The flexible sandstone here exhibited is a remarkable variety, the flexibility of which has been referred to the dissemination of small scales of mica through the mass. Several compact forms of silica are presented in the shape of hornstone, chert, and flint: in flint the silica appears to be partly in the soluble and partly in the insoluble state. Flints occur chiefly in the upper chalk, in the form either of nodules or of regular bands : some characteristic specimens will be found in the upper gallery. (See Catalogue of Rock Specimens, 3rd ed., p. 160.) Some of the applications of flint receive illustration here, and a collection of early flint implements is arranged in a case on the opposite side of the room (seep. 131).

In the mineral called opal, which is generally regarded as specifically distinct from ordinary quartz, the silica exists in an amorphous, soluble, and usually hydrous condition, having solidified probably from a gelatinous state. The noble or precious opal has always been a much valued gem. The Orphic poem commends the opal, saying it has the delicate complexion of a lovely youth. This gem, Pliny says, the Indians so well imitated in glass that the counterfeit could hardly be detected. He also tells us that a senator named Nonius possessed an opal valued at twenty thousand sesterces; that Anthony proscribing him, he fled, saving, of his whole property, this ring only. (Moore's Ancient Mineralogy.) The precious opal occurs in porphyry at Czerwenitza, near Kashau, in Hungary. The fire opal is brought from Mexico, and the common opal is abundant in Hungary, and is found in Faroe, Iceland, the Giant's Causeway, and the Hebrides. Hyalite, or Miller's glass, is a colourless transparent opal; while menilite is an opaque brown opaline concretion occurring in the tertiary strata of Mewl-montant, near Paris.

In this case are many examples, from Trinidad and other places, of the curious changes effected in wood by silicification; and in the first gallery will be found some larger specimens. Tho change has been so gradual that the woody structure is perfectly retained, and in the section of the palm trees in the gallery the arrangement of the cellular tissue is preserved..

Alumina

The coarser forms of alumina, or oxide of aluminium, having been already described under the names of emery (p. 33) and corundum (p. 96), it remains to notice, in this place, only those fine transparent varieties which, from their excessive hardness and beauty of colour, are highly valued by the jeweller. These pure forms of alumina are almost exclusively brought from the east, chiefly from Ceylon, Pegu, and Ava, where they occur embedded in sands and gravels.' The bright red varieties constitute the oriental ruby, so called to distinguish it from the totally distinct and much less valuable mineral, spinel, which is also known in commerce as "ruby." Sapphire is a name applied to the blue transparent crystals of corundum; Pliny's name of asteria being retained for the "star sapphires," or those varieties which exhibit a star of light when -cut with a convex face. Other brightly coloured corundums pass in commerce as "oriental" gems; the green as oriental emerald, the yellow as topaz, and the purple as amethyst; but it must be remembered that these oriental stones differ essentially, both in chemical composition and in physical characters—colour only excepted—from the gems whose names they bear.

The preparation and properties of metallic aluminium, the base of alumina, have been noticed-at p. 121..

Case M.—Anhydrous silicates

The large series of anhydrous silicates, occupying this case and the following one, embraces many minerals of considerable value as precious stones : of these the greater number are grouped together in the case before as. The double silicate of the allied earths alumina and glucina is known in its coarser varieties as beryl, of which enormous six-sided crystals are found in the United States. The fine transparent green varieties are distinguished as emerald, while those of paler tint pass under the name of aquamarine. The rich colour of the emerald is due either to oxide of chromium, -or to an organic colouring matter. The gem is chiefly obtained from the mines of Muzo in New Granada, where it occurs crystallized in a black carbonaceous limestone. Specimens will be found showing its occurrence in the matrix, accompanied by some fossils from the limestone.

Closely related to the emerald in chemical composition is the mineral called euclase, the excessive brittleness of which renders it useless for purposes of ornament. The earth glucina also occurs combined with alumina in the chrysoberyl or cymophane : certain varieties of this mineral, when cut en cabochon, exhibit a peculiar opalescence, whence the name oriental cat's-eye.

Among the small number of minerals which contain zirconia, the most important is the silicate called zircon. The transparent coloured zircons are used as gems; the rich red-varieties being distinguished as hyacinth or jacynth, and the less brightly coloured as jargoon. The hyacinth occurs in the form of rolled crystals, chiefly in Ceylon and central France; whilst the coarse dull-coloured;.irconite forms a constituent of the peculiar zircon-syenite of Norway, and is also found in the miascite of the Urals.

Few minerals present greater complexity and variability of composition than the tourmaline. Its crystals are remarkable for a want of symmetry between the opposite ends, and for acquiring electric properties on exposure to heat. The black tourmaline is commonly known as schorl, and the pink as rubellite a striking variation of tint in the same crystal is well seen in the parti-coloured tourmalines from Elba.

The group of garnets embraces a considerable number of minerals which are essentially double silicates, the varieties depending on the character of the bases. The deep-coloured almandine or precwes garnet, a silicate of alumina and protoxide of iron, is frequently cut en cabochon, when it is known as carbuncle : and the essonite or cinnamon stone, is also used as a gem, being often mistaken for hyacinth. Essonite is a silicate of alumina and lime, thus having a composition similar to that of the Siberian grossularia or gooseberry garnet. Another Russian garnet is the uwarowite, a mineral having a bright emerald-green colour, and containing the silicates of lime, alumina, and sesquioxide of chromium. The species idocrase or vesuvian has a composition identical with that of certain garnets, but crystallizes in forms totally distinct.

In the topaz, to which we next pass, a silicate of alumina is associated with a silico-fluoride of aluminium. The topaz is found in the form of rolled pebbles, and in granitic rocks commonly associated with quartz, and not unfrequently with tin ore. The yellow and the white topazes, chiefly from Brazil, form valuable gems; and in many cases a pinkish tint is developed by exposure to heat. The topaz of the ancients appears to have been the stone which we now call chrysolite : this is a silicate of magnesia of a dull green colour, known also as peridot, the name olivine being applied to the less transparent varieties, commonly found in meteorites, and in basalt and other trap rocks.

The spinel, or spinelle, of which the bright red varieties are used as a gem under the name of spinel ruby, is a compound of alumina and magnesia, the latter being frequently replaced to a considerable extent by protoxide of iron..

Case N.—Anhydrous silicates continued

The minerals in this case, although less attractive than those in the preceding section, are nevertheless of the highest interest as rock-constituents. At the head of the series stands the family of felspars, including a number of species, of which the best known is the potash-felspar, orthoclase. The transparent orthoclase called adularia is occasionally used for purposes of ornament under the name of moon stone. microcline and Amazon stone are two other varieties of orthoclase, the former noticeable for its beautiful opalescence, and the latter for its fine apple-green colour. Albite and oligoclase are closely-related soda-felspars, the soda being usually accompanied by lime in the latter species. Orthoclase-felspar, commonly associated with either oligoclase or albite, forms an important constituent of granite (p.17), whilst the soda-and-lime felspar labradorite is characteristic of the group of basalts (p. 38). Attention need scarcely be directed to the beautiful play of colour exhibited by the polished slabs of labradorite.

The well-known lapis lazuli appears to be a silicate of soda, lime, and alumina, with, probably, a sulphide of iron and sodium. It is found on the banks of the Indus in a crystalline limestone; and in limestone and granite it occurs in Persia, China, and Siberia. The richer varieties of lapis lazuli are employed in the manufacture of ornamental articles; and when subjected to careful powdering and washing, to free it from all foreign admixtures, it forms the ultramarine of the artist, which is so celebrated for its beauty and permanence. The rarity of the mineral, and the cost of preparation, render the true ultramarine of a very high price, 51. 5s. per ounce.

An artificial ultramarine is prepared by mixing clay, carbonate of soda, and sulphur, and carefully heating the mixture; the result is a very fine blue colour, which is said to be equally permanent with the natural lapis lazuli, and which can be sold at 8e. the pound.

The members of the mica family, of which several are here exhibited, differ from one another in crystalline form, optical characters, and chemical composition. They are important as constituents of granite, mica slate, and other rocks. A portion of an unusually large crystal of Canadian mica will be found in the lower part of Case 27.

Jade or nephrite is well known as a mineral which, in spite of its hardness, is largely worked into images and ornaments of various kinds by the Chinese; it is also found in Australia, New Zealand, and some parts of North-west America. Jade is essentially a silicate of lime and magnesia. Its name nephrite is derived from υεϕρος (nephros), kidney—it being used for diseases of that organ by some people. Some fine Chinese carvings in jade are in Case 43.

Passing over a few minerals, for the most part of interest only to the mineralogical student, we meet with a very instructive group, embracing the different varieties of the closely-allied species augite and hornblende. It is notable that the augitic minerals are characteristic of lavas, basalts, and other igneous rocks, which contain the more basic felspars; whilst the hornblendes occur in greenstone, syenite, &c., usually in company with highly silicated felspars and often with free quartz..

Case O.—Asbestos.—Hydrous silicates

The fibrous forms of hornblende and similar minerals are known as asbestos (inconsumable), from their power of resisting the action of intense heat; hence asbestos cloth, woven from the delicate threads, may be exposed to fire without being consumed. The delicate fibres are distinguished as mountain silk, while the massive forms resulting from the interlacing of these fibres are called, according to their texture, mountain leather, rock cork, 4-c.

Turning to the series of hydrous silicates, we recognize the well-known meerschaum (sea froth), so called in allusion to its lightness and white colour. This is a hydrous silicate of magnesia, found in Asia Minor, Turkey, Greece, Morocco, Spain, and Moravia.

The serpentines have been already described in connexion with the specimens in the (p. 21). The chlorites and other minerals in this case are not of very general interest. The Lemnian earth, formerly valued in medicine, was esteemed sacred, being mixed with goats' blood, and made into cakes, which were then stamped by the priests, whence it was called sealed or sacred earth. From the use of the agalmatolite by the Chinese for carving figures it has received the names of figure stone and pagodite. The apophyllite, a hydrous silicate of lime and potash—placed at the end of this section—forms a passage to the true zeolites occupying the next case. Especially noteworthy are the fine Indian crystals brought to light during the cutting of the railway tunnels on the stupendous inclines ascending the Bhore and Thul Ghauts (p. 97)..

Case P.—Hydrous silicates continued

The zeolitic minerals occupying the greater portion of this case are related by several characters in common. They are essentially hydrous silicates of alumina, with an alkali or an alkaline earth; and are usually found in the cavities of amygdaloidal trap-rocks, a few however occurring also in metalliferous veins. Beautiful in their crystalline forms, and interesting in their chemical composition and mode of occurrence, the zeolites are highly attractive to the mineralogist, but as they receive no practical applications, further notice in this place seems unnecessary..

Sulphates and phosphates of alumina

Passing over the sulphates of alumina—with which might be associated the double sulphates already noticed as the group of alums—we recognize among the phosphates of alumina the beautiful turquoise. This gem may be considered as a phosphate of alumina, coloured by oxide of copper. The mode of occurrence and the turquoise separated from the matrix are shown. The specimens exhibited were mostly presented by Major Macdonald, vv ho thus describes the locality in which he found them:—"In the year 1849, during my travels in Arabia in search of antiquities, I was led to examine a very lofty range of mountains composed of iron sandstone, many days journey in the desert; and whilst descending a mountain 6,000 feet high, by a deep and precipitate gorge, which in the winter time served to carry off the water, I found a bed of gravel, where I perceived a great many small blue objects mixed with the other stones; on collecting them I found they were turquoises of the finest colour and quality. On continuing my researches through the entire range of mountains, I discovered many valuable deposits of the same stones, some quite pure, like pebbles, and others in the matrix. Sometimes they are found in nodules varying in size from a pin's head to a hazel nut; and when in this formation they are usually of the finest quality and colour. * * * * Another formation is, where they appear in veins. They also occur in a soft yellow sandstone, enclosed in the centre, and of surpassing brilliancy.'

The Model Rooms

In the very limited number of pages which can be appropriated to a notice of the objects in this section of the Museum, it is impossible to introduce anything beyond the most brief descriptions : this, however, is the less to be regretted, since a special catalogue of this department has been prepared by Mr. Bauerman, to whose descriptions the visitor seeking further information is in all cases referred.

The Model Rooms are situated at the northern or Piccadilly end of the building, and comprise an eastern and a western room on the principal floor, marked respectively A and B; with a small supplementary apartment, C, approached from the lower gallery. As these rooms are not provided with gas, they are necessarily closed tit dusk.

On the right-hand side of the entrance to the eastern room is a model illustrating the plan adopted to condense lead fumes at the Wanlock Head Works, in Clydesdale (p. 128). Flat and round chants for mining purposes are fixed on each side of the doorway, and in front of these are three models of different forms of the man engine,—a German invention for facilitating the descent and ascent of miners. Immediately on entering the room will be found, on the left-hand wall, a sectional model of the workings of Dolcoath Mine, near Cam.-borne (M. 4)—one of the oldest, if not the very oldest, of the existing mines in Cornwall. The red wood in the model represents granite, and the white the killas or Cornish clay slate; the lode being shown by the black layer which extends over both these rocks- It should be understood that the spectator is to suppose the granite and slate are entirely removed from the side of the lode nearest to him, and that he looks upon a vertical section of the lode, and the workings by which- the metalliferous portions have been removed. The description of this model in the earlier editions of the Guide has been transferred to the Catalogue of Models. A case of safety fuses and cartridges is placed above the model of Dolcoath. The table at this end of the room is occupied by models of various forms of whims, or machines for raising minerals in mine-shafts.

A large and very perfect working model of Taylor's engine (H 5) at the United Mines, in Gwennap, occupies a prominent position in the centre of the room. The celebrated Cornish pumping engine, of which this is a model, performed the high duty of lifting one hundred and ten millions of pounds one foot high by the consumption of a single bushel of coal (94 lbs.) in the fireplace of the boilers.

On the table on the right-hand side of the entrance will be found a model of a Welsh blast furnace and blowing machine (N. 24). The air from the cylinder of the blast engine before entering the furnace flows through the regulator — represented by the large copper sphere—and, when the hot blast is employed, likewise passes through a system. of heated cast-iron pipes, the arrangement of which is also shown in the model. The remainder of the table-space is occupied by a model of a double-cylinder blast-engine, used at the Royal Saxon Smelting Works, on the Mulde. Passing over the models of pumping engines on this side of the room, we reach the large model of a water pressure engine at the Alport mines, Derbyshire (H. 4). This model, when viewed from below, shows the shaft in which the pumps are placed by which the water is drawn from the mine. Above is the tube for the columns of water, by the pressure of which the machine is moved. At the Alport mines an adit level or sough is driven to the mines from the banks of the river Derwent, a distance of three miles, so as to drain the mines to the depth of about 22 fathoms; and the water from the workings below this level is raised by three large hydraulic engines, of which the most successful was the one here represented, constructed at the Butterley works from the designs of Mr. Darlington.

A stand of wire ropes is fixed above the fireplace, in front of which stands a Cornish crushing machine. At this end of the room will be found several illustrations of boring machinery, the surface arrangements being represented by model C. 21, while the tools actually employed are mounted near the spiral staircase. On the left-hand side of the fireplace stands a large model (C. 22) of two forms of boring apparatus with free-falling cutters adapted for deep borings. Close to this is a model of a vertical water wheel employed for pumping at Wheal Friendship, near Tavistock (H. 2); and next to this, a case exhibiting the various forms of valves adopted in pumps for mining purposes (H. 13); aside of which stands a model of the turbine or horizontal water wheel (H. 3) on Fourneyron's principle.

Along the northern wall is a series of cases containing tools employed in various mining districts; and by examining these the miner of any one country or district at once becomes acquainted with the description of tools employed in another.

Leaving the eastern model room, the visitor enters the second apartment, which is devoted chiefly to illustrations of colliery workings.

Immediately facing the entrance is a model of the Forest of Dean (A. 14) by Mr. Thomas Sopwith. It represents a tract of country comprising the principal coal-field of the Dean Forest, the superficial area being 24 square miles. The outcrops or basseting of the principal beds of coal are shown on the surface, and vertical sections of the strata are painted on the sides of the model. In order to show similar vertical sections in the interior of the Forest, the model is made in compartments, placed on a sliding table, so as to be easily separated.<span

The large model (F. 15) in the centre of the room represents a colliery pit frame by Mr. W. H. Jordan. The drawing ropes, proceeding from the drum in the engine house, pass over the guide-rollers at the top of the shear frame, and are attached to the cages, or covered platforms, running on guide rods, and provided with safety catches. Behind the pit frame stands a model of Ebbw Vale and Sirhowy Iron Works in the county of Monmouth, (A. 13.) This model is by Mr. Sopwith; it comprises nearly four square miles of ground. The upper surface being taken off, the black pins mine, a vein of ironstone, with the workings in it, appear. Below this the three-quarter coal, modelling coal, and red vein mine are exhibited by removing successive trays which represent the intervening strata. In front of the fireplace is one of Ridley 4. Co.'s coal cutting machines, worked by compressed air. This machine, which has recently been introduced into several collieries, is intended to supersede manual labour in undercutting or "holing" in coal.

At this end of the room are two large models of Shipley Colliery, in Derbyshire (G. 1 and 2), presented by Messrs. Woodhouse and Jeffcock. From these accurate models an excellent idea may be obtained, not only of the most approved surface arrangements of a large colliery, but also of the underground workings. On the south side of the room are two models (G. 3 and 4) illustrating different modes of working and ventilating coal mines; and a model (A. 16) representing the physical appearances and the geological conditions of a coal district. On the opposite side of the room is a large model (F. 52) of a self-acting inclined plane at the Upleatham iron mines, in the Cleveland district of Yorkshire. Along the northern wall is a series of cages and safety skiffs. In most of these contrivances it is arranged that upon the breaking or cutting of the rope the cage or bucket shall be gradually or suddenly brought to rest by being wedged against the guides in which it travels. Before leaving this apartment attention should be directed to the instructive sections of the Yorkshire coal and Lincolnshire ironstone, and of the coal measures at the Rosebridge pits near Wigan; the former will be found at the western end of the room, the latter against the south wall.

Returning to the eastern model room, and ascending the spiral staircase at the S.E. corner, the visitor reaches the eastern end of the gallery leading to the third model room, C. On the north side of this apartment is a large German model (M. 6) illustrating the various mining and dressing operations as conducted in the Saxon lead mines at the close of the last century; and in the centre of the room stands a model representing the surface workings of a small Cornish tin mine (M. 3). Here will also be found a number of models illustrating various modes of supporting the ground in mining excavations by timbering and masonry, and of protecting wet colliery shafts by cast-iron, tubbing. In front of the fireplace is a small hand crusher, employed in some of the Derbyshire lead mines; and on the shelves in the south-east corner of the room is a series of geological models by Mr. Sopwith, whose descriptions of them have been transferred to the Catalogue of Models.

Passing from this apartment to the gallery of the model rooms, we find at the head of the staircase a model of a crane used for shipping large blocks of sandstone at the Redhall quarry; near Edinburgh (F. 53). On the adjacent table stands a model of a lead chamber for condensation of sulphuric acid vapour, produced by the oxidation of sulphurous acid (N. 35); and the reverberatory furnace at the side (N. 36) is designed for the production of sulphate of soda by the action of sulphuric acid on common salt, the sulphate being afterwards converted into soda-ash. The next model (N. 34) represents Mr. Young's apparatus for the manufacture of stannate of soda, a salt prepared by the reaction of tin stone and caustic soda; and this is followed by a model (N. 15) illustrating Pattinson's process for desilverising lead, which has been described at p. 110. Tile remainder of the table-space in this gallery is occupied by models representing several forms of blast furnace, some of which are provided with arrangements for utilizing the waste gases from the top of the furnace.

The four wall-cases in this gallery are appropriated to models of metallurgical furnaces, distributed as follows :—in Case 1 are several Saxon furnaces for lead smelting, with a Belgian zinc-, and a Cornish tin-furnace; Case 2 contains the apparatus employed in the Saxon processes for silver extraction; the next case, 3, is devoted to iron furnaces; and the last case, 4, contains three models of North of England lead-hearths, with one of Siemens' regenerative gas furnaces, &c.

At the western end of this gallery is a glass case filled with a large series of crystallographic models in wood and glass; while larger models adapted for the lecture table will be found on the upper shelves of the wall-cases in the large room on the ground floor.

Occupying the table-space in the western gallery are illustrations of several plans for ventilating mines, together with models of buddies, jigging frames, and other dressing machinery.

Commencing at the entrance to this gallery, the first wall-case, No. 5, presents a large display of mining lamps, among which the safety or Davy lamp for coal mines merits especial notice.

It will be seen that this is a lamp surrounded by wire gauze. The principles of its construction, arrived at by Sir Humphry Davy, by a very beautiful series of inductive researches into the character of flame, are the following :—Gas, in a state of combustion, will not pass through fine apertures. Hold a piece of wire gauze above a gas flame, it will be found that the flame will not permeate the gauze, although all the gaseous products of combustion pass it with great facility.

The light carburetted hydrogen gas, formed by changes taking place in the bed of coal, forms, when mixed with air, an explosive mixture, which is far too frequently of the most destructive nature. This gas passes freely through the wire gauze into the flame, and it is ignited within the lamp; but as the flame cannot pass out, no explosion takes place on the outside of the wire. When the carburetted hydrogen gas becomes in excess, the light of the lamp is extinguished. The miners complain of the deficiency of light from the original Davy, and hence various improvements have been introduced, of which several are here exhibited.

Passing over the windlasses and ventilating machines in the following case, we find the next section appropriated to Gay Lussac's apparatus for assaying silver by the wet way, that is, by precipitating the silver as chloride by the action of a solution of common salt, a method first adopted at the French mint. The remaining wall-cases in this gallery—the arrangement of which is not yet completed—&Main models of dressing machinery, described in detail in the special catalogue of models.

The Lower Gallery

The Palaeontological Collection

The two galleries, with the exception of the recesses in the upper gallery, are devoted to the illustration of the Fossil Geology of the British Isles. In this Guide it will be necessary to indicate merely the general order of arrangement, and to point to the larger groupgi referring for- further information to the Catalogue of the Collection of Fossils, which, in addition to a complete inventory of the specimens,. contains a valuable sketch, by Professor Huxley, of the general principles of natural history, and their application to the elucidation of Fossils or Paleontology.

Palæontology is the science of ancient life, the name being derived from παλαιὀς palaios, ancient; ὄντα onta, beings; and ,λόγος logos, a discourse or doctrine. The palæontologist, therefore, seeks to learn the order in which the forms of life have been developed, and he endeavours to make safe deductions from the discoveries of the geologist, by which he may advance scientific truth, and thus necessarily increase its powers of practical application.

The divisions which have been adopted for the purposes of grouping -together rocks with especial reference to their organic remains are as follow :—

		Laurentian.
Primary	Lower Paleozoic	Cambrian.
		Lower Silurian.
		Upper Silurian.
	Upper Paleozoic	Devonian.—Old Red Sandstone.
		Lower Carboniferous.
		Upper Carboniferous.
		Permian.
Secondary	Lower Mesozoic* [The middle forms of life, μέσος, middle, ζωή, life.]	Triassic.—New Red Sandstone.
		Lower Oolite.
		Middle Oolite.
		Upper Oolite
	Upper Mesozoic	Lower Cretaceous.
		Upper Cretaceous.
	Eocene [The dawn of recent life, ώἠς the dawn, καινὀς, recent.]	Lower Eocene.
		Middle Eocene
		Upper Eocene
	Meiocene [The less recent life, μείων, less, ,καινὀς, recent.]
	Pleiocene [The more recent life, πλεἱων, more, καινὀς recent. ]	Older Pleiocene.
Post-tertiary.		Newer Pleiocene

This table commences with the oldest known sedimentary rocks, and, neglecting minor subdivisions, proceeds thence in a regularly ascending scale. In arranging the fossils a similar plan has been adopted; and in examining the collection it should be noticed that the numbering, unlike that of the minerals and rock-specimens, proceeds from the lower part of the cases, the bottom shelf being always regarded as the first.

Palæozoic fossils

Im the first of the Flat-cases on the left-hand or western side of the gallery (l), and in the lower part of Wall-case, sections 12 and 13, will be found the earliest indications of fossil remains which have yet been discovered in the lowest of the Palæozoic rocks, or those in which the indications of the most ancient life appear,—with the exception only of the Eozoön, recently detected in the Laurentian rocks of Canada, Bohemia, Bavaria, and elsewhere (p. 118). There are in the Cambrian rocks near Dublin two species of branched or plant-like organisms, probably Zoophytes, called Oldhamia; and in rocks of the same age in Shropshire there are traces of worm-like animals (annelids), and a solitary trilobite, or what appears to be such.

Then follows the zone of Lingula flags .or lowest band of the Silurian system, which is characterized by its peculiar Trilobites, Lingulæ, &c.

In the next series of Flat-cases (2 to 7), we have a larger collection of Articulata (invertebrate animals with jointed bodies), from the Llandeilo and Caradoc formations. These are chiefly Trilobites, which being first clearly recognizable in the Lingula flags just noticed, become very abundant in the next overlying groups. In the Wall-cases, sections 12 and 13, will be found, among other fossils from the Lingula and Llandeilo beds, the curiously serrated creatures called Graptolites by Linnaeus,—γρἁϕω, grapho, I write, and λἱθος, lithos, a stone—from the resemblance of their remains in the stone to writing or sculpture.

Wall-cases, sections 14 to 16, are appropriated to fossils from the Caradoc or Bala beds, chiefly graptolites, corals, and Cephalopods, or creatures allied to the cuttle fish. and the.pearly nautilus.

Flat-cases 8 to 13 contain shells of the lower Mollusca belonging to, the Caradoc and Lower Llandovery rocks, the latter forming.: the upperrnost member of the Lower Sihiriam. group.

Wall-cases, sections 17 to 19, also contain the remains of Invertebrata, chiefly from the Llandovery beds.

Flat-cases 16 to 25 are devoted to certain fossils of the Upper Siltrian rocks, comprising the Upper Llandovery beds and the Wenlock and Ludlow groups. Trilobites, varying from the more ancient types, are still numerous; and with these are placed the Brachiopoda, Gasteropods, and Conchifera, from the same formations.

In the Wall-cases, sections 20 to 27, will be found the Upper Silurian Cephalopoda, Corals, and Crinoids or lily-shaped animals.

The following sections, 28 and 29, contain the Upper Silurian Crustacea (animals with a crust-like covering, such as we see in crabs and lobsters), among which may be remarked especially the remains of the great Pterygotus, a crustacean six or seven feet long. In the next section 30 will be found remains of the oldest fishes known,—Pteraspis, Onchus, &c.,—from the "Ludlow bone bed," which occurs just beneath the Downton sandstone; and from the beds, formerly called tilestones (by Sir R. Murchison), and considered to be the base of the Old Red Sandstone, but now classed by him with the uppermost Ludlow rock, and as beds of passage to the Devonian rocks. Other fossils from the same beds are arranged in the Flat-case 26.

From this well-marked division of ancient life, terminating with the fossil remains of the Upper Ludlow rocks, we advance to the Upper Palozoic period.

The strata known under the names of Devonian and Old Red Sandstone form the lower rocks of the Upper Paleozoic group. The mollusca of this formation—chiefly brachiopoda—will be found in the Flat-cases 27 to 35, and the cephalopoda, corals, and echinoderms in Wall-cases, sections 31 and 32; while the fish remains are arranged partly in section 30, and partly in sections 39 to 41, the latter containing a fine collection of the Old Red fish of Scotland —Coccosteus, Pterichthys, &c.

Passing to the Carboniferous system we find the lower carboniferous fossils in Flat-cases 36 and 37; and those from the mountain limestone in 38–47; the latter also containing a few fossils from the millstone grit; while the molluscs of the true coal-measures are in 18 and 49. The beautifully preserved echinoderms and cephalopoda from the carboniferous limestone are arranged in Wall-cases sections 33–38; and the carboniferous fish are distributed through sections 42–45; No. 47 being devoted to a few amphibian remains. In Wall-cases, sections 48 to 54, will be found some fine examples of coal-measure plants—Sigillaria, Lepidodendron, &c. These remains teach us that a great variety of plants, of decidedly a terrestrial character, flourished through that long period of time to which the formation of most of our numerous coal beds must be referred. Vascular plants—such as contain spiral vessels; cryptogamous plants, in their general character like ferns, mosses, club-mosses, and horse tails; and coniferæ, an order of plants which, like the fir and pine, bear cones in which the seeds are contained, are represented in the carboniferous rocks. From such vegetable creations as those, growing probably in great luxuriance under the influence of an elevated temperature, and decaying with much rapidity in an atmosphere charged with moisture, our coal beds were formed. (See Catalogue of Rock Specimens, 3rd ed., p. 66.)

The coal-measures are succeeded by the Permian rocks, forming the uppermost of the palæozoic series. The mollusca from this formation are grouped together in Flat-cases 50 and 51; and the fish remains in Wall-case section 46.

Before closing the notice of the lower gallery it should be mentioned that the wall-cases in the recesses on the western side, sections 1 to 11, containing tertiary and post-tertiary vertebrate remains, are still in process of rearrangement. The table-cases in the recesses on each side of this gallery are appropriated to a small zoological collection of certain typical specimens adapted for lecture illustration.

At the head of the staircase, on the western side, will be found the remains of Ichthyosauria, including a fine specimen from the lower lies of Street; and on the stairs of the eastern side, a remarkably perfect Plesiosaurus, from the same locality; with a, miscellaneous collection of the remains of vertebrate, or back-boned animals, from the secondary rocks.

Upper Gallery

Secondary and Tertiary fossils

Commencing at the left hand or eastern corner.

Passing over the few plants and other organic remains found in the Trim or New Red Sandstone of this country (see Wall-case, sections 8 and 9, bottom shelf), we find in the first flat-case fossils from certain rocks lying between the trim and the lias, and known as the. Penarth or Rhætic beds. The earliest known reptiles, Stagenolepis and. Telerpeton, occur in what is generally regarded as new red sandstone, and are represented in wall-case, section 26, which contains also other reptilia from the secondary rocks.

Occurring in extraordinary abundance, and in an excellent state of preservation, the fossils of the Oolitic system necessarily demand a somewhat large amount of space. The group of hassle rocks, forming the lowest member of the Oolites, is represented in Flat-cases 1 to 6, and in Wall-cases, sections 8 to 13. Ammonites—so called from the resemblance of this shell to the curved horn on the head of Jupiter Ammon—thronged the waters at this time, and gigantic cuttle-fish have left their internal "bones," Belemnites, (βέλεμνον, belemnon, a dart,) to tell of their abundance. In Wall-case, section 17, are some fine specimens of the crinoidal animals of the Has; and. a collection of Has fish from Lyme Regis is arranged with other Oolitic vertebrata in sections 22–24.

The remaining subdivisions of the lower Oolites, embracing the inferior Oolite, fullers' earth, Stonesfield slate, great Oolite, Bradford clay, forest marble, and cornbrash, are represented by an extensive series of fossils, displayed in Flat-cases 7 to 12, and Wall-cases, sections 11 to 16. No. 18 is devoted to certain plant remains from the lower Oolites, consisting chiefly of arborescent ferns, and of plants allied to the existing Cycas and Zamia.

The strata known as Kellaway's rock, Oxford clay, calcareous grit, and coral rag, form together the group of Middle Oolites, the characteristic fossils of which will be found in Flat-cases 22–26, and Wall-cases sections 14 to 21. The organic remains from the Kimeridge clays—the lowest of the upper Oolitic series—are placed in Flat-cases 27 and 28; those from the overlying Portland beds in 29 and 30; and the fresh-water shells from the Purbeck rocks in 31 and 32. Turning to the wall-cases, we find in sections 22–25 specimens of Oolitic fish; in 26, some interesting reptilian remains from the new red sandstone and Oolites; and in 27 a collection of fossil insects, &c. from the Purbeck group.

The lower division of the Cretaceous system embraces the Wealden beds and the lower greensand; the fossils from the former—for the most part fresh-water shells—are in Flat-cases 33–34; while those from the latter occupy Flat-cases 36–39, and Wall-cases, sections 28–30.

Flat-case No. 40 is appropriated to fossils from the Speeton clay of Yorkshire, a deposit commonly classed with the Gault; and a collection of the beautiful Gault fossils of Folkestone will be found in Nos. 41–43. The upper greensand is represented in the series 44–48; the beds known as chloride marl in 49 and 50; and the true chalk—both upper and lower—in 51–53. Other invertebrate fossils from the same group of rocks will be found in the Wall-cases sections 28–37; and the vertebrata in sections 38 and 39.

Having now reached the close of the secondary epoch, we advance to the tertiary division, including the Eocene, Meiocene, and Pleiocene groups.

The fossils of the Lower Eocene rocks receive illustration in the Flat-cases 54–57, and Wall-cases sections 47 and 48; while the Middle and Upper Eocene beds are represented in sections 48–51. A fine series of fossil shells from the Barton and Bracklesham beds will be found in the Flat-cases 58–63, and in the drawers beneath. The Meiocene plants, chiefly from the lignite-beds of Bovey Tracey, are grouped together in Wall-case section 52; the fossils of the coralline crag in 53; and those from the red and mammaliferous crags in 54; while section. 55 is devoted to remains from the newer pleiocene beds, and the remaining cases to a collection of post-pleiocene fossils.

Such is a rapid outline-sketch of this valuable collection of fossil remains, the study of which will be greatly facilitated by observing on the Geological Maps and stations the order which the respective formations observe to each other. Especially in the Memoirs of the Geological Survey and Museum of Practical Geology will information be found on these and other important allied subjects.

Geological specimens

The collection of GEOLOGICAL ROCK SPECIMENS will be found in the recesses of the second gallery. The third edition of a catalogue of these is published under the direction of Prof. A. C. Ramsay. It is, therefore, only necessary, in this place, to give a general notice of the principal groups.

The series of IGNEOUS ROCKS are arranged chiefly on the western side, commencing at the south-west corner with wall-case No. 1,: in which will be found some interesting examples of lavas and other volcanic products, from the promontory of Aden, at the mouth of the Red Sea, and from Kilauea and Hawaii, in the Sandwich Islands. These are followed by a series of greenstones, trachytes, and other igneous rocks from certain mining districts in Hungary, Croatia, and Transylvania. In this case are also grouped a few specimens from the Eifel, St. Vincent, and Teneriffe.

Wall-case 2 contains a tolerably extensive set of igneous rocks from Ascension Island, and the Galapagos Archipelago, presented by Mr. Darwin.

New Zealand also furnishes some interesting volcanic products, which are here exhibited.

The following case, No. 3, is occupied by a collection of specimens from the extinct volcanoes of the Rhine, and from the Island of Madeira. On the upper shelves of Cases 2 and 3 are some very characteristic models of limestone, gneiss, and other rocks, together with a model of the island of Bourbon.

Before passing to the next compartment it is desirable to notice the objects in the recesses on this side of the gallery. In the first recess, opposite Case 2, is an instructive model of Arthur's Seat, Edinburgh, showing the geological structure of that volcanic hill; and in the next recess, opposite No. 4, is a Table-case (A.), containing a model of Vesuvius, and an extensive series of Vesuvian rocks and minerals. With these are associated some specimens from Heels, and some samples of melted Rowley Rag (p. 38). In the same ease will be found an instructive model of Graham's Island, an island which was thrown up in the Mediterranean, near Sicily, in- the summer of 1831, and, after continuing some time in a state of violent eruption, gradually diminished in size, and finally disappeared about three months after its first appearance.

In the Table-case B, occupying the next recess, is a geological model of Etna, together with a valuable collection -of volcanic products from Etna, and from the extinct volcanoes of the Papal States.

Leaving the series of modern volcanic products, we turn to those rocks in which the igneous origin is less obvious, although still indubitable; such, for example, as the basalts. These are represented in the remaining wall-cases in the recesses on this side of the gallery; and with these truly igneous products are associated certain rocks of questionable origin, such as granite, serpentine, &c. As most of these have been already described in connexion with the objects in the hall, it will be necessary merely to give the references where such notices may be found. The series commences in Wall-case No. 4 with a collection of the different varieties of granite (p. 17), from which we pass through the group of syenites to the greenstones (p. 21), with which are exhibited samples of the ash, and other mechanical accompaniments of the trappean rocks.

The upper and lower shelves of Case 5 are appropriated to examples of the columnar basalt and associated rocks in the neighbourhood of the Giant's Causeway (p. 38); and in the same case are grouped some fine specimens of Cornish serpentine (p. 21). The remainder of this case, and the whole of the following one, contain specimens forming part of the collection of British stratified rocks, to be presently noticed.

Table-case C, at the head of the staircase on this side, is devoted to specimens illustrative of Glacial phenomena.

The common form of a glacier is that of a river of ice, filling a valley, and pouring down its mass into other valleys yet lower. It is not a frozen ocean, but a frozen torrent. The glacier moves on like a river, with a steady flow, although no eye sees its motion; but from day to day, and from year to year, the secret silent cause produces a certain slow effect. The movement of such a mass of ice as that which constitutes a glacier must be exhibited in enormous manifestations of force. Hence, we find the glaciers of the Alps grinding the rocks, on either side of the gorges through which they glide, with irresistible power. The specimens exhibited show the wearing and grinding force of the modern glaciers; and the discovery of similar scratches on the rocks of Snowdon and other places proves the presence, at one time, of glaciers in the mountain valleys of this country. See Prof. Ramsay's Remarks on Glaciers, in the Catalogue of Bock Specimens, and in The Old Glaciers of North Wales, Longman & Co.

Crossing to the opposite or eastern gallery we commence notice of the collection of BRITISH SEDIMENTARY ROCKS. These are arranged stratigraphically, in ascending order (see table of strata, p. 150), commencing in Wall-case 40, with the lowest of the Palaeozoic series, or oldest stratified rocks, represented by a small group of specimens from the Laurentian gneiss of the north-west of Scotland, and the adjacent islands. These are succeeded by the Cambrian grits, slates, &c., with their associated igneous rocks, chiefly from North Wales, the Longmynd, and Charnwood Forest. Above the Cambrian comes the Silurian system, the lower division of which comprises the Lingula and Llandeilo flags, the Caradoc or Bala beds, and the Lower Llandovery rocks. Neglecting minor subdivisions, the Upper Silurian series consists of the Upper Llandovery rocks and the Wenlock and Ludlow groups, including many beds of highly fossiliferous limestone. The Silurian rocks, which are chiefly from Wales, where they are very largely developed, are distributed through Cases 41, 42, and 43.

Between the Silurian and Carboniferous systems occur the slaty rocks of Cornwall and Devon, forming the Devonian group, and the strata long known as Old Red Sandstone, largely developed on the borders of Wales and in various parts of Scotland. The Carboniferous system, to which we now pass, is divided, in this country into the Carboniferous limestone, millstone grit, and coal measures. The Carboniferous or Mountain limestone is especially prominent in the north of England, where it forms the Pennine chain (p. 22); in Derbyshire it is associated with the "toadstone" (p. 23), of which several examples are here shown. The millstone grit has been noticed at p. 28. The "coal measures" is a collective term applied to the alternations of shale, sandstone, fireclay, coal, and ironstone, which occur associated in most of our coal fields. In Cases 43 and 44 will be found representatives of the coal measures of South Wales, Dean Forest, Coalbrook Dale, Flintshire, South Staffordshire, Warwickshire, Lancashire, Derbyshire, Yorkshire, and Northumberland.

The Permian rocks, overlying the coal measures, and forming the uppermost member of the Palaeozoic series, are represented by the conglomerates, dolomites, (p. 31,) &c. in Case 44.

Before concluding the examination of the Palaeozoic rocks, attention should be given to the table-cases in the recesses on this side of the gallery. These cases, marked respectively D, E, F, are appropriated to a collection of Scotch rocks from the Old Red Sandstone and Carboniferous systems, including a large series of the associated igneous rocks.

Turning to Case 45 we find the lower rocks of the Secondary or Mesozoic epoch, commencing with the New Red Sandstone or Trias. Above the Trias are the fossiliferous rocks known variously as the Penarth, Rhmtic, Westbury, and St. Kössen beds. These deposits form a transition to the overlying Lias (p. 29), a group of clays, argillaceous limestones, and marls, regarded usually as the base of the Oolitic system, and divided into an upper and a lower group, separated by the marlstone. The limestones of the Oolites have been noticed at p. 29; and the numerous subdivisions of the system at p. 153; each of these finds its representatives in Case 46.

The remainder of the collection of British stratified rocks will be found on the opposite side of the gallery in Cases 5 and 6, to which we now re-cross. The Oolitic series is continued in Case 5 (north side); the fresh-water deposits known as the Purbeck beds being there represented. Then follows the Lower Cretaceous group, comprising the Wealden beds and the overlying Lower Greensand.

The Gault, Upper Greensand, and Chalk, forming together the Upper Cretaceous series, receive illustration in the following Case, No. 6; where also will be found the Tertiary or Cainozoic rocks. These are divided into the Eocene, Meiocene, and Pleiocene groups (p. 151) of which the lowest, or Eocene, occupies two depressed areas in the chalk, known as the London and Hampshire basins, the latter extending to the Isle of Wight. These are followed by the Meiocene beds, which are but feebly represented in Britain, occuring only at Bovey Tracey, and in the Isle of Mull, while the Pleiocene rocks are represented by the Crags of our eastern counties. In this case are also grouped together specimens from the drift-gravels, boulder-clay, &c.; and, finally, in Case 6, we have a collection of specimens from raised beaches, caves, and other recent formations.

In front of the entrance to the Mining Record Office stands a model, by Mr. A. Geikie, F.R.S., illustrating the geological structure of the Isle of Eigg, in the Hebrides.

Proportional section of the Himalaya mountains, upon the panel near Wall-case 7.

The height from the floor of the principal room of the Museum to the line on the brass plate which represents the level of the sea, which is 27½ feet, being considered equal to the diameter of the earth, this section shows the height of the Himalaya mountains, as compared with that diameter. The height of the most elevated portion of this range approaches to 30,000 feet. The Earth's diameter being about 8,000 miles, it follows that the greatest elevation above the sea level is less than the 1,600th part of that diameter.

Against the door on eastern side will be found a scale of relative heights as a geological standard scale, suggested by Mr. P. Nasmyth.

A, B, represents an arc of a circle 6efeet in diameter, representing 120 miles of the Earth's surface, at the sea level, to the scale of 140th of an inch to a mile, on which are represented the relative heights of-

1st. Snowdon	3,571 feet.
2nd. Vesuvius	3,800 feet.
3rd. Etna	10,874 feet.
4th. Mont Blanc	15,732 feet.
5th. Mount Everest, Himalaya	29,000 feet.
6th. The deepest mines	2,200 feet.
7th. The probable average of the whole Earth above the level of the sea.

Several geological photographs, presented by Mr. J. J. Cole, F.R.A.S., are suspended against the panels at the southern end of the gallery.

In the south-east corner stands a model of the salt mine of Aussee, forming a companion to the two similar models on the principal floor, described at p. 130.

Sun and Planets.—Above the door of the Mining Record Office in this gallery is placed a gilded globe, which is intended to represent the Sun. At relative distances, in comparison with the size of this sphere, there are placed, upon projecting arms from the table-cases, representations of Mercury, Venus, and of Earth, with her satellite the Moon. This arrangement is intended to familiarize the mind with the immensity of space, and the size of the masses of those planets which are nearest the great centre of the system, in which the Earth is a small unit. The great size of the Sun will be conceived by looking at the Earth—a globe nearly 25,000 miles in circumference, and her satellite of a correct comparative size, at the proper relative distance from her. If the centre of the Sun and Earth were coincident, the Moon circulating in her orbit at the same distance from the Earth as she now moves, would revolve within the mass of the Sun, and leave a space beyond equal to the distance of the Moon from. us, before reaching the edge of the solar disc.

Megaceros Hibernicus (the Irish Elk).—The skull and horns of this remarkable animal, of which numerous remains have been found in the peat bogs of Ireland, are placed above the cases at the circular end of the upper gallery.—The antlers of large and full grown stags are among the most common remains of animals in peat. They are not horns which have been shed, for they are found attached to portions of the skull, proving that the whole animal perished.

Mining Record Office

This branch of the establishment owes its origin to a representation made to the Government by the British Association • at the meeting of that body at Newcastle-on-Tyne, in 1838.

The objects to which this office is devoted are:—

1st. The collection, arrangement, and preservation of all plans and sections of mines and collieries, both those which are now in process of work, and such as have been or may be abandoned.

2nd. The collection and publication of statistical information connected with the mineral produce of the United Kingdom.'

3rd. The collection and registration of every hind of information, connected with the phenomena of our mineral formations of whatever description these may be.

The President of the Geological Society, the Rev. Dr. Buckland, in 1841, who took an active part in the establishment of the MINING RECORD OFFICE, thus spoke of its objects :—" To the Keeper of these Records will be assigned the duty of arranging the documents which may be transmitted to him from all parts of the kingdom by any engineers, mineral surveyors, and proprietors of mines and coal works who may be willing to send them; particularly Maps, Sections, and Underground Plans, which will record the state of each mine when it is abandoned, for the information of those who, at a future period, may be disposed to bring it again into operation."

At the present time the MINING RECORD OFFICE contains a large collection of the Plans and Sections of abandoned and of existing mines, and a considerable amount of information connected with the mineral produce of the United Kingdom. To all parties who are specially interested in these industries, the collections of the office are opened upon application to the Keeper of Mining Records. Statistical returns of the mineral produce of these islands are published annually_.; these returns being indeed the only reliable information which is given to the public of a branch of British industry, the :value of which, independently of building stones and clays, may be estimated as exceeding 40,000,000l. per annum.

A Catalogue of the Documents in the Mining Record Office has been published.

The Lower Gallery

The Palaeontological Collection

The two galleries, with the exception of the recesses in the upper gallery, are devoted to the illustration of the Fossil Geology of the British Isles. In this Guide it will be necessary to indicate merely the general order of arrangement, and to point to the larger groupgi referring for- further information to the Catalogue of the Collection of Fossils, which, in addition to a complete inventory of the specimens,. contains a valuable sketch, by Professor Huxley, of the general principles of natural history, and their application to the elucidation of Fossils or Paleontology.

Palæontology is the science of ancient life, the name being derived from παλαιὀς palaios, ancient; ὄντα onta, beings; and ,λόγος logos, a discourse or doctrine. The palæontologist, therefore, seeks to learn the order in which the forms of life have been developed, and he endeavours to make safe deductions from the discoveries of the geologist, by which he may advance scientific truth, and thus necessarily increase its powers of practical application.

The divisions which have been adopted for the purposes of grouping -together rocks with especial reference to their organic remains are as follow :—

		Laurentian.
Primary	Lower Paleozoic	Cambrian.
		Lower Silurian.
		Upper Silurian.
	Upper Paleozoic	Devonian.—Old Red Sandstone.
		Lower Carboniferous.
		Upper Carboniferous.
		Permian.
Secondary	Lower Mesozoic* [The middle forms of life, μέσος, middle, ζωή, life.]	Triassic.—New Red Sandstone.
		Lower Oolite.
		Middle Oolite.
		Upper Oolite
	Upper Mesozoic	Lower Cretaceous.
		Upper Cretaceous.
	Eocene [The dawn of recent life, ώἠς the dawn, καινὀς, recent.]	Lower Eocene.
		Middle Eocene
		Upper Eocene
	Meiocene [The less recent life, μείων, less, ,καινὀς, recent.]
	Pleiocene [The more recent life, πλεἱων, more, καινὀς recent. ]	Older Pleiocene.
Post-tertiary.		Newer Pleiocene