THE LIBRARY OF THE UNIVERSITY OF CALIFORNIA DAVIS GIFT OF GLADYS LOUKE OUTLINES OF MINERALOGY AND GEOLOGY, COMPREHENDING THE ELEMENTS OF THOSE SCIENCES ; INTENDED PRINCIPALLY FOR THE USE OF YOUNG PERSONS. FOURTH EDITION, ENLARGED. BY WILLIAM PHILLIPS, F.L.S. F.G.S, &c. " Descriptions of facts, which must serve as the ground-work of theory, seem, in the present state of science, the most useful employment of the Geologist." Rev. W. D. Conybeare, LONDON: PRINTED AND SOLD BY WILLIAM PHILLIPS, GEORGE YARD, LOMBARD STREET. ^-. 1826 W fl ft vl ADVERTISEMENT TO THE FOURTH EDITION. Tins Edition is presented to the public in the hope that the additions it has received will contribute to increase its usefulness, as approximating it in some degree to the present state of the sciences on which it treats. With this intention, great alterations have necessarily been made, and Chapters on the following subjects have been added. Of Mineralogy , as essential to the Geologist. Of the arrangement of Rocks, and Descriptions of them individually with a Table ofSynonymes, French, German, and English. Sketch of the methods pursued in the working of Mines in Cornwall. Processes for obtaining the principal Metals by the reduction of their ores. Of the excavation of tallies. List of Mountains in England, Scotland, and Ireland, with their heights, and in some instances their composition. This little work, (its original form of Lectures is retained for the reasons given in the Preface) is intended chiefly for the use of young persons ; it may perhaps also prove of advantage to such as may be desirous of acquaintance with the subjects on which it treats to a limited extent, but who may have no intention of pursuing them as a study. But Mineralogy possesses many advantages as a study ; it be- longs equally to every season, and is adapted to any hour : with a far more limited number of objects than belong IV to some other departments of natural history, its interest to one who delights in it never ceases, because mere posses- sion does not satisfy the possessor ; for the characters of a mineral, either chemical or external, and the experiments which these suggest or afford, are always fraught with amusement and instruction ; composition, as well as crys- talline form, structure, specific gravity, relative hardness, and other external characters, 'possess unceasing interest, and leave no hour to the mineralogist vacant or unemployed. They afford pursuits demanding the use of the understand- ing, while they tend to its cultivation, and in common with the acquirement of natural knowledge in all its departments, tend also to raise in the mind a feeling of reference to the Great First Cause, and of gratitude for the multitude of bounties which, by means of the laws that we term na- ture, he has shed around us. PREFACE TO THE FIRST EDITION. THE motive for introducing this little volume to public notice, might seem to be wanting if it were not avowed. It is this: There is no elementary work on the subjects it embraces in our language ; no book that is calculated, by its simplicity and freedom from theory, and from the shackles imposed upon a learner by the unnecessary use of scientific terms, to invite his attention to the sciences of Mineralogy and Geology. It is not pretended that the following pages have any claim to originality : all the merit that belongs to them, if indeed any should be allowed, is that of combining in a narrow compass, an outline of sister sciences which merit a more general attention than is given them ; in an arrange- ment as simple as the subjects will readily allow, and in language which it is hoped will be intelligible to those who may have no acquaintance with them. The form in which these outlines are given, that of a division into Lectures, though not absolutely novel, is not common. During the last winter these Lectures were de- livered ut the neighbouring village of Tottenham, in the vi Preface. order in which they are now printed ; but with some defi- ciences supplied, and some errors corrected, that were in- cidental to hasty compilation. These Lectures were given gratuitously ; and the interest they seemed to excite in a numerous audience, principally composed of young persons, and of both sexes, was felt as a flattering compensation. But the form of Lectures is not adhered to on that ac- count alone. It allows of a familiarity not inconsistent with an elementary treatise, while it affords an opportunity for useful recapitulation, that perhaps would appear ob- jectionable in any other form; and for occasional repetition^ which, if the scientific should condescend to peruse it, may seem tiresome, but will, I have no doubt, be advan- tageous to the learner. In a work, by far the greater part of which is compila- tion, it may reasonably be expected that authorities should be quoted. That has not always been done in its pages. I therefore here acknowledge my obligation, in respect to the mineralogical part, to Aikin's Dictionary of Chemistry and Mineralogy ; and in the geological part, to the Trans- actions of the Geological Society, to Cuvier's Theory of the Earth, edited by Professor Jameson, to whose Geog- nosy I am scarcely less indebted. These works are my principal authorities ; many others were occasionally con- sulted, but were not made use of in a degree that seems to render their enumeration requisite. If the perusal of this little volume should tend to create in any person the desire for a knowledge of the sciences on which it treats, beyond their mere elements ; it must be owned that it is difficult to refer the reader to works in the English language that are adapted to the use of the learner. The only means by which a knowledge of mine- Preface. vii ralogy can be acquired, is an acquaintance with minerals : and I have no hesitation in recommending those who may feel this laudable anxiety for further information in respect to these interesting pursuits, to the acquirement of it by means of small collections ; which may be had of one hun- dred varieties arid upwards, with an arranged catalogue, of Mawe, 149, in the Strand, at any price between ^5 and 100. One of these little collections * would materially assist the progress of the learner ; more especially if ac- companied by a studious attention to the Manual of Mine- ralogy, by Arthur Aikin, Secretary to the Geological Society. The introduction to that work forms a valuable compendium of mineralogical information : and though the learner will meet with many terms and names that will demand explanation, it may be said to be the only work in our language that will be found of advantage to him. The study of geology should follow that of mineralogy. Small collections of rocks may also be obtained. The Geognosy of Jameson is altogether a scientific work, not well adapted to the learner ; inasmuch as a pre- ponderating anxiety for the support of a favorite theory, has caused the introduction of many terms not hitherto adopted by English mineralogists; but much useful and valuable information may be gleaned from it. W. P. London, 1815. * The collections first recommended by the late Dr. Clarke of Cam- bridge, may also be had t>f G. B. Sowerby, Regent Street, and of Stuchbury, Dove Court, Poultry. LECTURE I. Preliminary Observations Objects of Mineralogy and Geology defined Elementary substances, page 3. Simple and compound minerals Affinity Of the EARTHS, p. 11. Of the ALKALIES, p. 23. LECTURE II. Of the METALS, p. 29. Of COMBUSTIBLES, p. 61. LECTURE III. Of CRYSTALLIZATION, p. 71. Of MINERALOGY as essential to the GEOLOGIST, p. 82. LECTURE IV. Of the Objects of GEOLOGICAL INQUIRY, p. 86. Hypotheses GEOLOGICAL POSITIONS, p. 97. Of the low and level parts of the Earth Of the Chalk Basins of Paris, London, and the Isle of Wight, p. 100. LECTURE V. Organic remains visible in hills, and on the sides of elevated mountains, p. 110. Strata of the BROCKEN MOUNTAIN, p. 123. Summits of lofty mountains contain no organic remains. LECTURE VI. Of the ARRANGEMENT OF ROCKS, p. 127; TABULAR VIEW of ROCKS generally, p. 129; and DESCRIPTIONS of them in- dividually, p. 130 TABLE OF SYNONYMES, French, German, and English, p. 181, LECTURE VII. Of MINERAL VEINS, p. 185. Of MINING, as practised in Cornwall, p. 194. Processes employed in reducing the METALLIC ORES, p. 212. Of SALT DEPOSITS, p. 240. Of the DELUGE, p. 246. Of the EXCAVATION OF VALLIES, p. 254.- Concluding observations, p. 275. APPENDIX. LIST OF MOUNTAINS in England, Scotland, and Ireland, their heights and composition. CONTENTS. MINERALOGY. Page Preliminary observations 1 Objects of Mineralogy and Geology defined , 2 Definition of the term Mineral Of MINERAL ELEMENTS and Constituents 3 Their number a list of them 4 Of OXYGEN HYDROGEN WATER 5 Certain ACIDS and their composition PHOSPHORUS 6 FLUORINE NITROGEN CHLORINE BORON 7 Several that we term elements, are not simple bodies Their enumeration 8 Mineralogy greatly dependant on Chemistry Of simple and compound minerals _ 9 Explanation of the term Oxide (note) , Water of Crystallization '. 10 Affinity Of the TEN EARTHS ; not simple bodies 11 Silex 12 Of Specific Gravity (note) Minerals of which Silex forms 50 per cent 13 Alumine 14 Minerals of which it forms the greatest ingredient 15 Zircon Its minerals 16 Glucine Minerals, into the composition of which it enters b x. Contents Mineralogy. Page Yttria 16 Minerals into whose composition it enters 17 Barytes Minerals of which it is an ingredient Strontian Its minerals 18 Lime 19 Its minerals 21 Magnesia Its minerals 22 Thorina Minerals of which it is an ingredient Proportions in which the Earths are found Of the FOUR ALKALIES ; not simple bodies '. 23 Potash 24 Minerals of which it is an ingredient Soda 25 Minerals of which it is an ingredient Minerals which contain both Potash and Soda 26 Lithia 27 Minerals containing it Ammonia Its minerals Of SELENIUM 28 Its minerals Of the TWENTY-EIGHT METALS 30 Ten only are malleable, the rest brittle Characters of the Metals generally 22 Platina 33 Is found only in the native state Gold _ Native ; its ores are few 34 Silver 35 Its ores are numerous Quicksilver 36 Its ores 37 Lead _ Its ores are very numerous Copper 39 Its ores are very numerous 40 Tin 41 Its ores are only two Iron 43 Its numerous ores . 44 Contents Mineralogy. xi Page Zinc 45 Its ores 46 Palladium _ Native ; Nickel 47 Its ores are few Cadmium Is found only in certain ores of zinc Arsenic ^ Its ores 48 Antimony 49 Its ores Bismuth Its ores Cobalt 50 Its ores Manganese 51 Its ores Tellurium 52 Its ores Titanium Its ores 53 Columbium Its ores . . . - Molybdena Its ores 54 Tungsten r Its ores Chrome . I 55 Occurs only as an oxide or acid Osmium, Iridium^ Rhodium Occur only as alloys Uranium 56 Its ores Cerium Its ores 57 The Metals are found chiefly in veins Their relative proportions in nature 58 Of COMBUSTIBLES 61 Their bases are Carbon and Sulphur 62 List of combustible minerals Sulphur Carbon 63 Combustibles of which it forms the base Diamond , ~~" %'H, Contents Mineralogy. Page Mineral Carbon 65 Plumbago Mineral Oil - Bitumen 66 Coal 67 Hatchetine 68 Amber M ellite 69 Retinasphalt 70 Fossil Copal Of CRYSTALLIZATION 71 Of the term, Crystal - Of the term, Salt (note) - Structure ; cleavage 72 Passage of the cube into the regular octohedron Practical illustrations 73 Primary form ; its meaning 75 List of Primary forms Octohedron its varieties Tetrahedron 76 Hexagonal prism Rhomboidal dodecahedron Parallelepiped its varieties 77 Transition of the octohedron into the rhomboidal dodecahedron 79 A crystal is a geometrical form The meeting of its planes subject to calculation Proofs of their being so 80 Of the Common Goniometer , 81 Of the Reflective Goniometer Of MINERALOGY AS ESSENTIAL TO THE GEOLOGIST ... 82 Only a limited acquaintance with minerals essential to him.... 83 Lists of those with which he must become acquainted Mode of studying them recommended GEOLOGY. Of the objects of Geological inquiry , 86 The ancients ignorant of Geology Geology, very modern, as a science Hypothesis of Burnet, Woodward and others 87 More modern theories of Bertrand, Marschall, and Jameson 88 Of thu theories relating to the agency of fire and water 91 Contents Geology. xiii Page Principal tracts of low countries 92 Strata of low and level countries are horizontal 93 Low and level countries contain sea shells Sea shells found in hills far above the sea And at the foot of great chains of mountains 95 Here, the strata are nearly vertical Many catastrophes by the agency of water Summits of lofty mountains contain no shells 96 And are therefore termed primitive .. . GEOLOGICAL POSITIONS 97 Proofs that low and level countries contain organic remains 98 Strata of the Chalk basin of Paris described 99 Strata of the Isle of Wight Chalk basin described 103 Strata of the London Chalk basin described Depth of wells around London , 104 Diluvum lying on London Clay The order of these strata is never inverted 105 Proofs that catastrophes by water have been extensive Bones of the rhinoceros, hippopotamus, elephant, abundant. 106 Found only in alluvial soil in low countries Never in, rocks Account of the mammoth found in Siberia (note) 107 Additional proofs of the extensiveness of those catastrophes 108 Rock of Gibraltar encloses bones of the antelope and mouse. Bones of the ox, horse, ass, sheep, land shells, and serpents, in others 109 Proofs that organic remains are found in hills 113 Cliffs of the Isle of Sheppey enclose fossil fruits, and remains of animals Beds of oyster shells near Reading, &c. and in France, &c.. Shells in the sides of Mount ^Etna 114 Proofs that shells are found at the foot of chains of mountains ... . Proofs that the strata, here, are nearly vertical 115 Rocks succeed each other in regular order 116 Secondary rocks known by the shells they enclose Proofs that the summits of lofty mountains contain no shells 117 Of the summits of high mountains The nature and position of their masses If in their primitive state 118 Division of rocks into primitive, transition, and flcetz 119 Primitive rocks, are chemical deposits, contain no organic remains 120 Transition rocks, are both chemical and mechanical depo- sits, and contain organic remains xiv Contents Geology. Page Difference between a chemical and a mechanical deposite, (note) 120 Fleets: rocks chiefly mechanical deposits, and contain or- ganic remains Section of the Brocken mountain 123 Of THE ARRANGEMENT OF ROCKS, and DESCRIPTIONS OF THEM, INDIVIDUALLY 127 The best is that \vhich is nearest their natural order Hand- specimen not always adequate for the determination of their nature Order of description 128 Tabular view of their arrangement 129 SUPERIOR ORDER . 130 1. Upper Freshwater formation 131 2. Upper Marine formation 3. Lower Freshwater formation 132 4. Lower Marine London Clay 5. Plastic Clay 133 StJFERMEDlAL ORDER 134 6. Chalk - 7. Greensand 135 8. Iron-sand 136 9. Oolites 137 10. Quadersandstein 139 11. Muschelkalk - 12. New Red Sandstone 140 13. Magnesian Limestone 141 MEDIAL ORDER 143 14. Coal-measures 15. Mountain Limestone 145 16. Old Red Sandstone 147 SUBMEDIAI, ORDER. 17. Greywacke 148 18. Transition Limestone 149 19. Greenstone , 150 Hemithrene 20. Quartz rock 151 21. Serpentine 22. Diallage rock 152 Euphotide 23. Clay-slate 153 Calschiste Alum-slate Whet-slate Flinty-slate Contents Geology. xv Page 24. Chlorite-slate 155 25- Talcose-slate 156 26. Steaschiste INFERIOR ORDER 157 27. Hornblende rock Hornblende schist Actynolite schist 28. Primary sandstone ; 158 29. Primary limestone 159 Cipolin Ophicalce Calciphyre Dolomite 30. Mica-slate 160 Hyalomicte 31. Compact felspar 161 White-stone Eurite Leptinite 32. Gneiss 162 33. Granite 163 Graphic granite Protogine Granite veins TRAP ROCKS, OVERLYING ROCKS 165 34. Wacke 166 35. Claystone Domite 36. Clinkstone 167 37. Compact felspar Ophite Hornstone porphyry Melaphyre Trachyte 38. Pitchstone 168 39. Basalt 169 40. Augite rock Dolerite Mimose 41. Hypersthene rock 170 42. Amygdaloid . . . 171 43. Cornean : Aphanite Vakite Trappite 44. Greenstone trap 172 xvi Contents Geology* Page 45. Sienite 172 46. Trap tuff 173 VOLCANIC ROCKS. 47. Lava 48. Obsidian 174 49. Pumice 175 50. Volcanic conglomerate 51. Volcanic tuff Travertine ALLUVIUM AXD DILUVIUM . Their difference Origin of Diluvium 177 Universal in its consequences Conglomerates of the older rocks 178 The Earth covered by herbage before the deposition of greywacke 179 The superincumbent beds deposited slowly British islands formerly Spice islands ? 180 ROCKS TABLE OF SYNONYMES, French, German, % English 181 Of MINERAL VEINS 186 SKETCH OF THE METHODS PURSUED IN THE WORK- ING OF MINES IN CORNWALL 194 PROCESSES FOR OBTAINING THE PRINCIPAL METALS BY THE REDUCTION OF THEIR ORES 211 Gold Silver 214 By the furnace By amalgamation Iron 217 Tin 221 Copper 224 Lead I "... 227 Zinc 231 Platina 233 Mercury 234 Manganese 335 Antimony 236 Arsenic 237 Cobalt 238 Of SALT DEPOSITS 240 Of THE DELUGE 247 Of THE EXCAVATION OF VALLIES 254 Of VOLCANOS 259 APPENDIX HEIGHTS OF HILLS : 279 In ENGLAND 281 SCOTLAND 287 IRELAND.. 290 LECTURE I. Preliminary Observations Objects of Mineralogy and Geology defined Elementary Substances Simple and Compound Minerals Affinity Of the Earths Of the Alkalies. THE outlines of the sciences of Mineralogy and Geology, which I am now about to attempt, are not intended to involve all the nicer inquiries, connected with the subject, that have been instituted by scientific men. Nor do I propose that they shall in any degree be dependant upon, or connected with, the many crude and almost barbarous theories of others, who long amused and even dazzled the world by the splendour of inventions, which tended to retard, rather than to forward, an inquiry into the nature of the Earth. The phenomena presented by nature are worthy of our notice ; to these your attention will be principally invited. Of the nature of the earth we comparatively know but little ; our investigations are at the best but superficial. We know nothing but of what appears ow, or above^ or of what is brought to light by the descent of the miner beneath^ the general level of its surface ; but the miner rarely de- scends more than 1500 feet, which is little more than *_dth part of the diameter of the earth. The globe has often been said to resemble in shape, an orange ; in allusion to that resemblance, we may therefore say, that we know nothing but of the outer rind. The greater number of mineral substances are to the gene- rality of mankind only rude masses, divested of instruction, and equally unintelligent and unintelligible ; created only 2 Objects of Mineralogy and Geology. to minister to our necessities. To some, it may be even difficult to imagine how they should become the objects of a distinct science ; or that after the miner has brought them to light, the naturalist should find an interest in them pre- viously to their being subjected to the ingenuity of the artist. The sciences of Mineralogy and Geology are, however, worthy of our attention ; they will be found to perform more than they seem to promise. The more we know of them, the more of order, of design, and of contrivance we shall perceive. The power that created the whole is evident in the smallest component part of the most elevated mountain. Mineralogy has for its object the study of mineral bodies in particular; their elements, characters, varieties, forms, and combinations. It also comprehends what may be termed the Natural History of Minerals ; as, the circumstances and positions in which they occur, and ,the substances with which they are found ; the history of their uses and pro- perties may be termed economical Mineralogy. Geology embraces the study of the earth in general ; of its plains, hills, and mountains, and of the relative positions of the masses of which they are composed. Geology comprises the study of the mass ; Mineralogy, of the individual portions, or substances which, by entering into combination, form the mass. A knowledge of mine- ralogy is therefore essential to the geologist, and for this reason we shall begin with Mineralogy. A mineral is an unorganised body, and differs from an organised or living body, in respect of structure and of the manner of formation, and of increase or growth. Organised bodies increase by means of their internal organs, which allow of an internal circulation, approxi- mating and assimilating what is beneficial, and of rejecting what is useless, and this mode of growth is termed by the physiologist, intus-susception : unorganised bodies on the contrary increase externally, and possess no internal organi- sation, the particles composing them being attached by mere juxta-position. Of Mineral Elements and Constituents. 3 In the organised, the particles constituting them, may generally speaking be considered as dissimilar ; in unor- ganised, as similar particles. Organised and unorganised bodies also differ essentially in respect of external form. In organised bodies we rarely perceive a plane surface, a determinate solid angle, or a strait line ; all these are however constantly perceptible in the unorganised ; more- over the former cannot be divided without destruction, whereas the latter may be almost infinitely divided without destruction. It was anciently supposed, when science was under the dominion of fancy and metaphysics, that all natural sub- stances were ultimately resolvable into four simple bodies, viz. air,Jire, water, and earth, which hence were called the four elements. The ancients however confessed that the precise nature of the two first, air and fire, was not known to them. They supposed most liquids to be modifications of the third element, water ; and that the solid parts of the globe were attributable to the last ; that is, the element they called earth. Thus, combustible bodies they supposed to contain a combustible earth, and metals a metallic earth. To modern chemistry we are indebted for a large cata- logue of Mineral elements and constituents. In this catalogue are comprehended 10 earths, 4 alkalies, and 28 metals ; other substances, enumerated at page 5, as the bases, or acidifying principles, of certain acids found in combination with, or in other words, mineralizing, some of the earths, alkalies and metals, have therefore also a claim to be con- sidered as mineral constituents ; two of these substances, forming the bases of the carbonic and sulphuric acids, namely carbon and sulphur, are also the bases of the combustibles. Water is also an essential ingredient of certain minerals. I now proceed to a short sketch of the nature of each of the foregoing ; and for the sake of convenience, shall con- sider them separately in the order of the following list : A 2 4 Of Mineral Elements ELEMENTS OR ACCESSARY CONSTITUENTS OF MINERALS. Oxygen Hydrogen Water certain Acids , which will necessarily involve some consideration of Phosphonu Fluorine Nitrogen Chlorine Boron to which will succeed some account of Selenium the 10 Earths 4 Alkalies and 28 Metals and of the bases of combustible minerals Carbon and Sulphur. Oxygen, in the most simple state in which it has been ob- tained, is in that of a gas, termed oxygen gas, in M hich it is combined with caloric, or heat. It is essential to animal life ; the acidifying principle of most of the acids; and, when we come to treat of the nature of the earths and alkalies, it will be seen that, as a constituent of them, it is one of the most, if not the most common and abun- dant of mineral elements. Of the most plentiful of all mineral substances, silex, it forms 50 per cent. ; of alu- mine 47 ; of lime 28 ; of magnesia 40 ; of potash 17; and of soda 25 per cent ; to which may be added that it forms about 88 per cent, of water, and that in the ores of tin and manganese, and in many of those of iron, lead, and copper, &c. oxygen enters as an ingredient in various proportions. Hydrogen^ in like manner, is obtained only as a gas in union with caloric or the matter of heat. It enters into the composition of several mineral constituents, is the acidi- and Constituents. 5 fying principle of some of the acids, and is emitted from the crevices of volcanic matter. Water is composed of oxygen and hydrogen in the propor- tion of about 88| of the former, to 11| of the latter. It is a constituent of many minerals ; and in a few is con- sidered to be an essential element, because the other constituents, in its absence, assume a form, different to that which is assumed when it is present.* It is an essential element of all acids. Acids have a sour taste, and redden vegetable blue colours. Their properties, and, in most cases, their names, are derived from their bases. Oxygen enters into the com- position of most of them ; hydrogen of two or three. The following acids are found in some one or more minerals. Their names are generally derived from their bases. Acid. The Carbonic Aci Phosphoric Fluoric Sulphuric Muriatic Nitric Boracic Tungstic Chromic Molybdic Arsenic Succinic Mellitic Base. Id consists of Carbon Phosphorus Acidifying principle. and Oxygen . . Oxygen . . Hydrogen .. Oxygen . . Hydrogen . . Oxygen . . Oxygen . . Oxygen . . Oxygen .. Oxygen . . Oxygen Oxygen fy llyd. Fluorine Chrome Molybdenci . unknown The carbonic, phosphoric, fluoric, sulphuric, muriatic, nitric, boracic, and arsenic acids, are found in combination with certain of the Earths. * This is the case with the two kinds of sulphate of lime ; of the com- mon variety, or selemte, water is an essential ingredient ; but the other, the anhydrous sulphate, is without water; and the primary forms of their crystals are very diflcrrnt. 6 Oj Mineral Elements The carbonic, phosphoric, sulphuric, muriatic, tungstic, chromic, molybdic, and arsenic acids are found mine- ralising certain of the metals. The nitric and carbonic acids are found united with pot- ash. The carbonic, sulphuric, muriatic, and boracic acids occur combined with soda. The succinic and mellitic acids are found in certain com- bustible minerals. Having preceded this view of the acids, by some account of their acidifying principles, oxygen and hydrogen, I pro- ceed to the nature of their bases. Phosphorus, as a mineral constituent, is found only in the form of an acid ; but when obtained from that acid, by depriving it of its oxygen, or by a chemical process from calcined bones, phosphorus is a highly inflammable sub- stance of a flesh-red colour, very soft, and not quite twice the weight of water. The chemist is induced to suppose that hydrogen is one of its elements. The phosphoric acid is found united with lime, and with lead, copper and manganese. Fluorine has not yet been seen in a simple or separate state. The fluoric acid, of which fluorine is the base, occurs in combination with the earths, lime and alumine, but has not been detected in combination with any metal, except cerium. Nitrogen has been obtained only in the form of a gas. It immediately extinguishes a flame, and is fatal to animal life. By some chemists it is supposed not to be a simple or elementary substance, but, on the contrary, that it consists of oxygen united with some unknown base. It forms an ingredient of ammonia, one of the alkalies. The nitric acid occurs combined with potash, another of the alkalies. Chlorine has never been found pure in nature. Its claim to be considered a mineral constituent rests on its being the base of the muriatic acid, which enters largely into the composition of rock salt, and in less proportion ia and Constituents. 7 found in combination with lead, silver and quicksilver ; but is not found in any earthy mineral. Boron is a substance that is not completely understood ; but it is ascertained to be a substance differing from every other known species of matter. Combined with oxygen, in the form of bpracic acid, it is found in combination with the earths, magnesia and lime, in few rare minerals, and with soda, forming borax ; but has not been detected in any metalliferous substance. The bases of the tungstic, chromic, molybdic, and arsenic acids, tungsten, chrome, molybdena, and arsenic, being metals, will be treated of under that head. Those of the carbonic and sulphuric acids, carbon, and sulphur, will be noticed hereafter as the bases of combustibles. The remaining Mineral Elements, according to the fore- going list, are 10 Earths, 4 Alkalies, 28 Metals, together with carbon and sulphur, the two bases of combustible minerals ; but as the view I propose to take of Mineralogy^ divides the whole number of mineral bodies into four great classes, of Earthy, Alkaline, Metalliferous, and Combustible substances, some account of each of them will be found under their proper heads. It may not be amiss to premise that The Earths are not simple elementary bodies, having each been decomposed and found to consist of oxy- gen united with a particular base. The Alkalies have also been decomposed ; three of them consist of oxygen united with particular bases; the fourth consists of nitrogen and hydrogen, the nature of which has already been considered. The Metals are considered to be simple bodies not one of them has been decomposed. Of the two bases of Combustible substances, carbon and sulphur, the first is considered to be a simple elementary substance, and is the base of the carbonic acid, which is found united with several of the earths and metals ; the latter, sulphur, is known to consist in part of hydrogen, and oxygen is also suspected 8 Definition of to be one of its elements. It occurs combined with several of the metallic bodies ; and as the base of the sulphuric acid, with several of the earths and metals, and with soda. From what has preceded, it will appear that some of the numerous mineral consituents are considered to be simple or elementary bodies^ because the chemist has not been able to decompose them ; such are the metals, carbon, oxygen, hydrogen, nitrogen. Others have been partially decom- posed ; such are some of the earths, sulphur, and phospho- rus ; of others the nature is not perfectly understood ; as chlorine, fluorine, boron, and some of the acids. Others again are compounds, whose composition is known; such are some of the earths, the alkalies, some of the acids, and water. Hence it appears that the nature of several mineral ele- ments and constituents is not yet understood ; and that the progress of mineralogy is greatly dependent on the advance of chemistry, which is yet far from perfect as a science. It may nevertheless be said that, according to the present state of our knowledge, the foregoing substances contribute to form all the various constituent masses of the crust of the globe.* * Such are the elements of inanimate creation ; the animate however appears to be composed of fewer elements. It is admirably observed by my friend J. G. Children, that " with four simple elements (oxygen, hydrogen, carbon, and nitrogen, a brief alphabet for so comprehensive a history) has a bountiful Providence composed the beautiful volume of the living world; where, turn to what page we may, fresh loveliness meets the eye, fresh cause of admiration and delight " (Essay on Chemical Analysis, p, 271.) That part of the creation, therefore, which is ar.imate, is compo ed of some of the same elements as the inanimate: and, according to the pre- sent state of our knowledge, the elements employed by the great Artificer of the Universe, in the formation of the globe, and of all the animal and vegetable creation, scarcely exceeds the number of fifty, reckoning as elements some substances which are suspected to be compounds. And when we reflect upon the fact, that a very few of these actually constitute a very large proportion of the whole; upon the nature of these elements, that several even of those which have been employed the term Mineral. 9 A simple mineral substance, pure Gold for instance, may be described as an unorganised body, presenting an assem- blage of lesser portions of the same nature, united by the agency or force of a natural law, to which I shall presently advert ; chemically, it may be described as a substance that has neither been decomposed nor formed by art. Compound mineral bodies are naturally found in some instances simply aggregated, in others chemically combined. When simply aggregated, as for instance, when gold occurs in limestone, their separation may be effected mechanically, by pounding and washing ; but when chemically combined, as when silver occurs united with sulphur, we must depend on the labours of the chemist for their separation. Such of the earths, alkalies, and metals, as are naturally found combined with various acids,* are then said to be mineralized by them. in by far the most important degree, have either eluded our research, or are known to us chiefly by their agencies; upon their wonderful arrangement, subservient to the purposes of organization in the living, and structure in the inanimate; upon the affections and properties of matter in general ; we may adopt the language of the Abbe Haiiy, and say, that Nature is thus exhibited " under an aspect which claims for its Author, die tribute of our admiration and our reverence." * Atmospheric, or common air, is composed of two very different kinds of air, or gas, viz. oxygen gas, and azotic, or nitrogen gas, in the proportion of 22 of the former to 78 of the latter. Oxygen gas, being that part of common air which is essential to ani- mal life, has been also called Vital Air; oxygen gas is composed of oxygen united with caloric, or the matter of heat, whence oxygen is termed the basis of Vital air. When a substance is combined with a small proportion of oxygen^ the compound is called an oxide: when with a larger proportion, it is called an acid, from the sour taste which most of these compounds possess ; and chemists have arranged with the acids some compounds which have not been proved to contain oxygen, because their general resemblance to the acids in other respects, is. sufficient to warrant the opinion that the similarity holds in this particular also. When oxygen is combined with iron, the compound is termed oxide of iron. Oxygen by combining with a certain proportion of carbon or charcoal forms an acid, called the carbonic acid : which, united with lime, forms a compound mineral called carbonate of lime, of which one variety is limestone, and another is chalk. B 10 Affinity. Such of the metals as are found in combination with oxygen^ are then termed oxides of those metals ; and in that state (to use a familiar illustration) bear the same affinity to those metals, as rust does to iron ; rust being the con- sequence of the absorption by iron, of oxygen from atmos- pheric air; it is an oxide of iron. This chemical combina- tion with oxygen, causes the metals to assume appearances quite different from the same metals in the pure state ; as for instance, the red oxide of copper is of a ruby red colour, and frequently almost transparent, and the oxide of tin when pure, is nearly colourless and transparent. To shew the liability of mineral bodies to become compound^ it may be noted that the ore called white silver, has been found to contain four metals, silver, lead, antimony, iron ; two earths, alumine and silex; and one combustible, viz. sulphur. The water which enters more or less into the composition of some mineral substances is termed water of crystallization , when these substances possess a regular structure. The law to which an allusion was just now made, as being that to which are subject the elementary substances, of which the masses constituting the globe are composed, is called Affinity. This law may be said to involve in it, all those termed attraction, gravitation, magnetism, and electricity. To the law of affinity, mineral bodies owe their existence in separate and similar masses, as well as their regular crystalline forms ; and but for this important law of nature, the solid parts of the globe would only have been a chaotic mass, instead of exhibiting, even in the oldest rocks, deposits of distinct substances frequently in regular crystalline forms. Of the Earths. OF THE EARTHS. I shall now offer to your notice some observations on those substances which are termed Earths ; they are ten in number. 1. Silex. 6. Barytes. 2. Alumine, or Argil. 7. Strontian. 3. Zircon. 8. Lime. 4. Glucine. 9. Magnesia. 5. Yttria. 10. Thorina. All these earths agree, when free of foreign admixtures, in this one character, they are all snow-white. Barytes, strontian, lime, and magnesia, agree so nearly with the alkalies in some of their chemical properties, that some chemists have given them place among the alkalies ; others have termed them alkaline earths. Although these substances by common consent retain the name of Earths, it seems essential, in speaking of them as mineral constituents, to say that chemistry, which, during the last twenty-five years has made amazing progress, has by the brilliant discoveries of Sir Humphrey Davy, completely turned the tables on the ancients. They supposed that every metal had an earthy basis, whereas his experiments tend to shew, that several of the earths have metallic bases ; that, in fact the whole number of them are not simple or elementary substances, but compounds, consisting of oxygen united with certain bases ; and, if it be admitted that these bases are metals, the Earths, in their purest form, to use the same familiar illustration as before, have the same affi- nity to their respective metallic bases, as rust has to iron ; they are metallic oxides. The earths whose bases are best known are those called barytes, strontian, and lime ; they are considered by Sir H. Davy to be metals. Strictly there- fore we ought to diminish the number of earths, by the three in question, and to increase the number of metals ; but as discoveries however brilliant and however well established, are rarely admitted with instantaneous consent, B2 12 Of the Earths. these metallic oxides are still suffered to hold their places as earths. I now proceed to give some account of each earth sepa- rately, and shall offer to your inspection some specimens of substances in which they prominently enter into combina- tion^ or are mineralized by an acid. Silex. This is one of those earths which the discoveries of Sir H. Davy have not decidedly shewn to have a metallic basis; its base he has called Silicium^ which he is now of opinion is not a metal, but a substance of a peculiar nature. 100 parts of silex consist of 50 parts of silicium and 50 of oxy- gen ; it is not therefore a simple elementary body. Silex in its pure state is not three times as heavy as water ; its specific gravity* is not quite 3. It has neither taste nor smell, and has never been found combined with an acid. As common flints are almost wholly composed of siliceous earth, it has from that circumstance received the name of * The specific gravity of a body is its weight, compared with that of another body of the same magnitude. Thus, if a cube foot of water weigh 1000 ounces, and a cube foot of iron 7000 ounces, their comparative weights or specific gravities are, as 1000 to 7000, or as 100 to 700, or as 10 to 70, or as 1 to 7. Now a cube foot of distilled water weighs 1000 ounces, which as we have just seen may be called 1000, or 100, or 10, or 1, as convenience may require for the sake of comparison, for in taking the specific gravity of a body, of a mineral for instance, we must always have a standard of comparison : this standard is by common consent, distilled water. Reckoning then distilled water as 1, we have seen that iron is 7; that is to say, when equal bulks of water and iron are weighed, the iron is found to be seven times heavier than water, its specific gravity is 7. It is by weighing minerals first in the air, and afterwards in water, that their specific gravities are determined; thus it has been found that rock crystal or quartz is more than twice and a half heavier than water ; and that the greater part of the earthy minerals are somewhat less than three times their weight of water ; their specific gravity is under 3.- That of melted silver is about 10-5 (10), that of melted gold is 19'2; that of platina is aboat 19'5, but when beaten it is about 22. Of the Earths. 13 j which in Latin signifies Flint; but this earth is found in greater purity in opal, and in quartz or rock crys- tal. Silex is probably the earth which most abundantly enters into the composition of the globe. It is proved by analysis to enter, in variable proportion, into the com- position of about two-thirds of all the earthy minerals whose composition is known^ including some of the hardest of the gems, and the softest of the clays ; and as it is the chief ingredient of the oldest and most plentiful of the primitive rocks, and is found in rocks of almost every age and for- mation, it is esteemed to be the most abundant substance in nature. Of the minerals mentioned in the following list, Silex forms about 50 per cent, or upwards : the small portion of iron they occasionally con- tain, and other accidental ingredients, are omitted here, and on all future occasions. Silex may be said to be the sole constituent of Rock crystal Most sands Cats-eye or and and some Quartz Sandstones Varieties of Opal. Silex, and a very small proportion of Alumine, constitute Flint Jasper Hydrophane Chalcedony Hornstone Menilite. Silex, alumine and water, Karpholite. Silex and lime, Tabular spar, Jeffersonite, Lievrite. Silex and magnesia, Bronzite. Silex, alumine and lime, Garnet, and Heulandite Indianite its varieties Thomsonsite Lapis lazuli Cinnamonstone Scolezite Dipyre Idocrase Wernerite Laumonite Gehlenite Zoisite Most slates Prehnite Epidote and Stilbite Axinite Clays Silex, alumine and magnesia, Fahlunite. Silex, alumine, barytes, Harmatome. Silex, lime, magnesia, Amianthoide, Augite and its several varieties. Silex, alumine, lime and magnesia, Hornblende and Anthophyllite Schiller spar its varieties Hypersthene Smaragdite Asbestus 14 Of the Earths. Silex enters largely as a component part of glass, for which purpose the pure white sand from some parts of the coast of Norfolk, and Alum Bay in the Isle of Wight, are preferred. Alumine. Alumine has been so called from its forming the basis of common alum. When pure, it has neither taste nor smell, and is twice as heavy as water. Though one of the most extensively diffused substances, it is no where found pure ; but the oriental ruby, the saphire, and corundum, which are the next in hardness to the diamond, consist nearly of pure alumine. Alumine forms a large proportion of that valuable mineral called fullers' earth,* which has that smell whrn breathed on which is peculiar to clayey substances, and forms a mineralogical test of the presence of alumine ; but as iron has always been found to be an ingredient in such minerals as give out this odour, it is reasonably con- cluded to be the consequence of the combination of iron, probably in the state of an oxide, with alumine. It occurs combined with the sulphuric acidfi in alum, and with the phosphoric acid, in the Wavellite. Alumine consists of oxygen united with a base, Alumium, the nature of which has not been completely ascertained, in the proportion of 47 parts of the former, and 53 of the latter. It has never been found in the pure state. It is an ingredient, in large proportion, of some of the most abundant rocks, primitive, secondary, and alluvial, and is found in all soils ; it is the most abundant of all the earths except silex. Alumine is a constituent of clay, whence this earth has obtained also the name of Argil, from the Latin, argilla, clay ; whence also, earthy substances, giving -out the pecu- liar odour before mentioned, as wll as other minerals, rocks, and clays, of which alumine forms any considerable proportion, are termed Argillaceous Sujfrffgfncet ; although * Fullers' earth consists of about 52 per cent, of silex, 25 of alumine, 3 of lime, 1 of magnesia, 3 of oxide of iron, and 16 of water. + Alum consists of ihe sulphuric acid, alumine. potash, and water. Of the Earths. 1 5 argil rarely forms more than one fourth, or one third part of most clayey substances, of which the predominating in- gredient is silex. Of the earthy minerals included in the following list, alumine forms by far the most important ingredient. dlumine constitutes almost entirely Corundum and its varieties, the Oriental Ruby and Saphire. Alumine and water, Diaspore, Gibbsite, Calaite. Alumine and silex, Fibrolite Kyanite Automalite Finite Staurolite Topaz Alumine, silex and water, Siliciferous hydrate of alumine, and several other minerals, its varieties. Alumine, silex, lime, Pycnite, Chrysoberil. Alumine and magnesia, Spinelle Ruby. Alumine, silex, magnesia, Pleonaste. Alumine, sulphuric acid, Subsulphate of alumine. Alumine, phosphoric acid, Wavellite. Alumine, lime, magnesia, Turnerite. Alumine, silex, lime, magnesia, lolite, Lazulite. In useful purposes, alumine enters largely into the com- position of bricks, pottery, and porcelain ;* it is infusible by any heat less intense than that of the voltaic electricity. gircon. Zircon when pure, is rough to the touch, insipid, and insoluble in water ; it is found combined with other sub- stances only in a few rare minerals ; as in the hyacinth, from a brook called Expailly, in Auvergne in France ; and * Brisson observes that porcelain was first manufactured in Japan and China, and that it is composed of two very different substances, the one argillaceous, the other vitrescible. The Chinese call the first Kaolin, the second Petunse. The porcelain clay of our country, at least that which is so abundantly found in some places in Cornwall, is a per- fectly white clay, apparently the consequence of disintegration of felspar, formerly perhaps a constituent of granite, since by washing the clay for the porcelain manufactories, it is cleared of fragments of quartz and of mica. Felspar in its natural state consists of about 66 parts in the 100 f silex, 18 parts of alumine, and 16 of potash. 16 Of the Earths. in the jargoon from Ceylon. Hitherto zircon has not been put to any useful purpose ; it is about four times as heavy as water. Zircon has however been proved to be composed of oxygen united with a base, Zirconium^ the nature of which is not known ; nor have the proportions of zirconium and oxygen been determined. Zircon and silex constitute Hyacinth, Jargoon, and Zirconite. Glucine. Glucine obtained its name from a Greek word signifying sweet, on account of the sweet taste by which its salts are distinguished. When pure, glucine is a white powder, soft, and somewhat unctuous to the touch, and is nearly three times the weight of water. The nature of its base, Glucinium,^ which by a natural combination with oxygen constitutes glucine, and in which they exist in the proportion of 70 per cent, of the former, to 30 of the latter, is unknown. Glucine has hitherto only been found in small proportion in the beryl, the emerald, in euclase, and the gadolinite ; but neither the pure earth nor any of its salts have hitherto been applied to any use. Glucine, silex and alumine constitute Euclase. Glucine, silex, alumine and lime, Beryl. Glucine, silex, alumine, lime and chrome, Emerald. Yttria. Yttria, in many of its properties and appearances in its pure state, bears considerable affinity to glucine ; it has the same saccharine taste, but is easily distinguished from it, inasmuch as it is nearly five times heavier than water, and by some properties discoverable only by the chemist. It has been ascertained by Sir H. Davy that oxygen enters into the composition of yttria, but the base Yttrium^ with which it is combined, has not been seen in a separate form ; nor have their respective proportions been deter- mined. Of the Earths. 17 It is an extremely rare earth. Yttria occurs as a com- ponent part of the mineral substance, called gadolinite, which is brought only from Sweden, and which was so called on account of its having been first analyzed by the Swedish professor Gadolin, who named the earth yttria^ because the mineral in which it was discovered was brought from Ytterby in Sweden. Besides the minerals included in the following list, it occurs entering into the composi- tion of another scarce mineral, Yttrocolumbite, also from Sweden. Yttria, glucine, and alumine constitute Gadolinite. Yttria, cerium, fluoric add, Double fluate of Cerium and Yttria. Yttria, cerium, lime, fluoric acid, Yttrocolumbite. Barytes. Barytes has never been found pure in the natural state, but always combined, either with the sulphuric acid form- ing sulphate of barytes or heavy-spar ; or with the carbonic acid forming carbonate of barytes, or witherite. Barytes and carbonic acid, constitute Witherite. Barytes and sulphuric acid, Heavy spar. Barytes is found forming very small proportions of two or three other minerals. These substances, which do not enter into the composi- tion of rocks, but are only found in veins, may readily be distinguished from other earthy minerals, by their superior weight, being more than four times the weight of water. Barytes and all its salts, except one, are violent and certain poisons, destroying animals by inflaming the intestines, and are often used for the destruction of vermin. Barytes is not a very abundant earth. It is one of those that have lately been decomposed by Sir H. Davy ; who discovered that it consists of oxygen united with a base, which he de- nominates Barium^ and which has the appearance of a dark grey metal, requiring considerable force to flatten it, and having a lustre inferior to that of cast-iron. At the ordi- nary temperature of the air it was solid, but became fluid c 18 Of the Earths. at a heat below redness. By exposure to the air barium became tarnished and fell into a white powder which was barytes. A portion of barium, thrown into water, acted upon it with great violence, and sunk to the bottom, pro- ducing barytes by absorbing the oxygen of the water, which it decomposed, evolving hydrogen gas ; but it has not yet been produced in quantity sufficient to allow of a minute examination of its chemical or physical qualities. Barium and oxygen constitute barytes in the proportion of 90 parts of the former, to 10 of the latter. Strontian. Strontian has never been found in a pure state. It was first brought, combined with the carbonic acid, from a place in Argyleshire, called Strontian, whence the mineral ob- tained its familiar name of strontianite. Strontian com- bined with the sulphuric acid is found near Bristol ; thus combined, the mineral has obtained the name of coelestine, from its delicate tint of a light blue colour. Strontian, carbonic acid, water, constitute Strontianite. Strontian, carbonic acid* barytes, lime, Barystrontianife. Strontian, sulphuric acid, Ccelestine. Strontian also occurs in small proportion in Arragonite. Strontian consists of oxygen, united with a base, Stron- tium, in the proportion of 16 of the former to 84 of the latter ; this base is believed more nearly to approach the nature of the metals, than those of some of the preceding earths. Strontium has been obtained in a separate form, but in very minute quantity. It resembled barium ; had not a very high lustre, was difficultly fusible, and not vola- tile, and was converted into the earth Strontian by absorb- ing oxygen on exposure to air, or on contact with water. Strontian may be considered as a rare earth. Either when pure or combined with the acids above mentioned, strontian has not hitherto been applied to any use. At present therefore the above combinations merely serve to form parts of a mineralogica! collection. Of the Earth*. 19 Lime. Lime has never yet been found in a pure state, but when so prepared by the chemist, is moderately hard, and of a hot acrid taste. It has been proved by Sir H. Davy to con- sist of oxygen united with a basis, considerably resembling some of the metals. This base he calls Calcium ; it has the colour and lustre of silver, but the chemist has not yet been able to examine it, for on exposure to air and heat it instantly takes fire and burns with an intense white light, and by the absorption of oxygen is reconverted into lime. Lime is therefore considered to be a metallic oxide, consisting of 28 per cent, of oxygen and 72 of calcium. It rarely occurs but in combination with certain acidsj as the carbonic, sulphuric, boracic, arsenic, fluoric, nitric^ and phosphoric. Lime combined with the carbonic acid forms a mineral substance, thence termed carbonate of lime, which is very abundant. Carbonate of lime, when crystallized, is com- monly called calcareous spar. It assumes a vast number of regular and beautiful forms, all originating in a rhomboid, which may always be obtained by fracturing the crystals. Those minerals commonly called limestones, and chalk, and marble, are also carbonates of lime. The rocks on each side the Avon near Bristol, are of a peculiar kind of limestone, which has obtained the name of swine-stone, from its yielding when rubbed a fetid smell. This smell was heretofore attributed to the presence of bitumen, but is now believed to be owing to sulphuretted hydrogen. Carbonate of lime is so abundant, that it is estimated to form one-eighth part of the whole crust of the globe. Lime in combination with the sulphuric acid, is chemi- cally termed sulphate of lime; mineralogicallyj it is called selenite when crystallized, gypsum when compact. Of this mineral the uses are very extensive. A compact variety of it, called alabaster, is employed by the architect for co- lumns and other ornaments, being more easily w r orked than marble ; it is also turned by the lathe into cups, basins, vases, and other similar articles. When sulphate of lime 20 Of the Earths. or gypsum, is subjected to a certain heat, it loses what is termed its water of crystallization, and is converted into a fine powder called plaster of parts ; the uses of which, when beaten up with water into a paste, for taking casts of gems and statues, are well known. Lime combined with the arsenic acid^ forms a mineral called pharmacolite, the only species : with the boracic acid, it forms a mineral called the datholite. Lime combined with the Jluoric acid^ is called fluate of lime or fiuor. This mineral is commonly known by the name of fluor spar ; in Derbyshire, as blue John. The elegant vases and chimney ornaments turned by the lathe out of blocks of this substance, are known to almost every one ; the brown colour generally observable in these vases is obtained by exposure to heat. Fluate of lime is ex- tensively used in smelting the ores of copper. The mineralogist values the fluate of lime for its abun- dant and beautiful variety of crystals both in form and colour. The octohedron may be obtained from each of them, however unlike to it, by breaking it in certain directions. A variety of fluate of lime, called chlorophane, found in Siberia and Cornwall, on being exposed to the heat of a live coal gives out a beautiful green light. Lime in combination with the phosphoric acid, forms a mineral which occurs in small crystals, called apatite,* or phosphate of lime. In combination with the nitric acid^ it forms a mineral called nitrate of Iime 7 which occurs in silky efflorescences on old walls, and sometimes in mineral waters. Lime is obtained artificially by heating the various species of carbonates, until the carbonic acid is driven off; hence the lime obtained for cements and agricultural purposes. In the form either of carbonate or sulphate, lime enters into the composition of marles ; which generally speaking are clays including a variable proportion of carbonate of * Apatite yields 55 of lime and 45 phosphoric acid. Of the Earths. 21 lime, to which their value as manure is chiefly owing. Limestone when burnt affords excellent manure, unless it contains any proportion of magnesia, which is always inju- rious, sometimes fatal, to vegetation. Lime and carbonic acid constitute Calcareous spar Marbles Limestones Chalk. Lime, carbonic acid, strontian, Arragonite. Lime, magnesia, carbonic acid, Bitterspar Dolomite Pearlspar Magnesian limestone. Lime, phosphoric add, Apatite. Lime, fluoric acid, Fluor. Lime, sulphuric acid, Anhydrous Gypsum. ., Lime, sulphuric acid, water, Hydrous Gypsum, M.- Lime, nitric acid, water, rNitrate.of lime. Lime, boracic acid, water, Datholite. uutfk Lime, arsenic acid, water, Pharmacolite. Magnesia. Magnesia is a light earth of a perfect whiteness, and ig absolutely insipid ; the slightly acrid taste occasionally to be found in the magnesia used in medicine, arises from a proportion of lime. It occurs in New Jersey, so nearly pure, that in the native magnesia of that country, it is com- bined only with water, or a small proportion of lime and iron. It is combined with the carbonic acid in the mag-i nesite ; and with the boracic acid in the borate of magnesia, or boracite ; f it has also been found in small crystals, in certain earths, and in the water of some springs, combined with the sulphuric acid, forming sulphate of magnesia; which, extracted from the water of a spring at Epsom in Surry, is therefore commonly termed Epsom Salts. J Magnesia consists of oxygen united with a base, mag- nesium^ the nature of which is imperfectly known; it is f The Boracite is composed of about 17 parts of magnesia and 83 of the boracic acid. J Epsom Salts consist of 19 per cent, of magnesia, 33 of sulphuric acid, and 48 of water. 22 Of the Earths. however considered by some chemists to be a metal ; hence magnesia is a metallic oxide, consisting of 40 per cent, of oxygen and 60 of magnesium. Magnesia is not an abundant substance ; it enters into the composition of about 30 minerals, but, in most of them it is not the prevailing ingredient. It forms a small pro- portion of the substance called the soap-stone, \vhich owes its greasy or soapy feel to magnesia. The soap-stone is largely employed in the manufacture of porcelain. Magnesia and water constitute the Hydrate of Magnesia. Magnesia, silex, Chrysolite, Olivine, and Condrodite. Magnesia, silex, alumine, lime, Serpentine. Magnesia, carbonic acid, Carbonate of Magnesia. Magnesia, carbonic acid, iron, Carbonate of Magnesia and Iron. Magnesia, sulphuric acid, Sulphate of Magnesia. Magnesia, boracic acid, Boracite. Thorina. This earth was first detected in the gadolinite, already noticed as containing the rare earth yttria; afterwards in combination with the rare metal cerium, in a mineral found at Finbo, near Fahlun in Sweden. It has a greater analogy with zircon than any other body, and they occur together at Finbo ; but they differ essentially in their chemical pro- perties, although they exhibit the same properties before the blowpipe. This earth has been named by Berzelius, Thorina, from the Scandinavian deity Thor. These ten earths enter, in very different proportions, into the composition of the globe. It is considered that silex is the most abundant of all. It forms the greatest ingredient of the oldest rocks, is largely found in others, and in all clays and soils ; in these alumine is the next in abundance; to it succeeds lime, which is less common in primitive rocks, though very plen- tiful in the transition and flcetz, or secondary rocks. Magnesia and barytes occur in comparatively very small quantities. The first enters but little into the composition of rocks and soils ; the latter rarely. Of the Earths. 23 Strontian, zircon, glucine, yttria, and thorina, are very sparingly found ; the first is the most common of the four j the others are only found in part the components of a few mineral substances, some of which are occasionally enclosed in rocks ; hut rarely does any of these four earths enter into the composition of rocks or of soils. Barytes, magnesia, strontian and lime, are never found pure ; but mostly combined with acids. It has been re- marked that these four earths agree so nearly with the alkalies in some of their chemical properties, that some chemists have given them a place among the alkalies ; others have termed them alkaline earths. OF THE ALKALIES. We now proceed to those mineral substances termed ALKALIES, which enter into the composition of several minerals. The term Alkali is Arabic, and is expressive of the acrid saline residue left in the ashes of the plant called Kali, after its combustion in the open air, and not being volatilized by a moderate heat, was termed Fixed Alkali. But there is another Alkali, differing essentially in respect of com- position from the Fixed Alkalies, but agreeing with them in certain chemical properties, which, being volatilizable at a moderate heat, is therefore termed Volatile Alkali. FIXED ALKALIES are usually denominated of two kinds. The Vegetable or Potash^ and the Mineral or Soda. Potash is procured from the ashes of vegetables in general, not growing contiguous to the sea. Soda is the basis of com- mon salt, and is therefore found in immense quantities ; it is also the principal saline residue procured by the com- bustion of plants growing on the sea shore. Both potash and soda, as well as lithia^ another alkali of very modern discovery, may be chemically considered as 24 Of the Alkalies. metallic oxides, since they consist of oxygen united to par- ticular bases, which in certain respects resemble some of the ' metals. These metallic bases. Potassium, Sodium, and Lithium, by exposure to oxygen, absorb it, and thus be- come alkalies again : they are lighter than water, and there- fore are six times lighter than the lightest of the metals, tellurium. The taste of the fixed alkalies, is acrid, burning and nauseous, they are without smell ; they have peculiar che- mical properties which it is not essential to our present object to notice. Potash. Potash occurs in the natural state in felspar, and in mica, two of the three substances constituting the oldest of the primitive rocks, and in about twenty other minerals : therefore the term vegetable alkali, as applied to potash, is not absolutely correct. The combustion of certain plants causes a residuum, of which potash combined with the carbonic acid, or carbonate of potash, is an ingredient, and is the potash of commerce ; but whether it existed in the plant, in that state previously to combustion, has not been determined. Potash is found combined with the nitric acid, forming nitrate of potash, commonly called nitre or salt- petre. It is chiefly found in minute crystalline fibres on the surface of dry chalk plains, or on old walls, &c.* Potash, silex, and alumine constitute the following minerals, Mica, Leucite, Andalusite, Bucholzite. Potash, silex, and lime, Apophyllite. Potash, silex, alumine and lime, the following ; Scaly Talc Pearlstone . Felspar and its Haiiyne Gieseckite varieties. Potash, magnesia, Talc, Green Earth. Potash, silex, alumine, magnesia, Soapstone and its varieties, Chlorite, Schorl, Krllinite. Potash, nitric add, Nitre. Potash, alumine, sulphuric acid. Alum. Potash, silex, alumine, sulphuric acid, Alumstone. _ * Nitre consists of 49 parts of potash, 33 of nitric acid, and 18 of water*, Of Ihe Alkalies. 25 Soda. Soda is found naturally combined with the carbonic acid, forming carbonate of soda, which occurs both in the mineral and vegetable kingdoms. As a mineral it is found in the hot springs of Iceland, in the lakes of Egypt and Hungary, and in a solid state, beneath the soil in Fezzan in Africa. In the vegetable state, it is procured by the combustion of certain plants, and is called Barilla and Kelp. Soda like- wise occurs in combination with the sulphuric acid, forming Sulphate of Soda, which is found in an efflorescent state, or, more commonly, dissolved in certain mineral waters, and in certain lakes of Hungary and Siberia, &c. ; when purified of its iron, the sulphate of soda is used in medicine under the name of Glauber's salt. Soda, combined with the boracic acid, is chiefly brought from certain lakes in Thibet, under the name of Borax, which therefore may be termed chemically, Borate of Soda ; but is said to be found also in Ceylon, Tartary, and Peru. In combination with the muriatic acid, Soda forms Muriate of Soda, or common Salt,* which occurs plentifully in certain springs of our own and other countries, and in vast deposits beneath the surface of the earth. On this subject I shall hereafter treat more at large. It likewise enters into the composition of several earthy minerals ; of which however it does not form any very considerable proportion. Soda,silex, alumine, constitute Cleavelandife. Soda, silex, alumine, lime, Mesotype and its Sodalite Clinkstone varieties Spinellane Pitchstone Sommite Lythrodes Lava. Rubellite Analcime Soda, silejc, alumine, magnesia, Basalt. Soda, silex, zircon, lime, Eudyalite. Soda, carbonic acid, Natron. * The water of the ocean contains from one twenty-fifth to one thirty- fifth of its weight of muriate of soda, or common salt, which is composed of 53 parts of soda, 47 of the muriatic acid. 26 Of the Alkalies. Soda, sulphuric acid, Sulphate of Soda, Soda, nitric acid, Nitrate of boda. Soda, boracic acid, Borax. Soda, muriatic acid, Common Salt. Soda, alumine, fluoric acid, water, Cryolite. Soda, lime, sulphuric acid, Glauberite. The following minerals yield by analysis both potash and soda. Potash, soda, silex, alumine, constitute Pumice, Compact Felspar. Potash, soda, silex, alumine, lime, Jade and its Obsidian Scapolite varieties Fettstein Chabasie. Potash, soda, silex, alumine, magnesia, Gabbronite. Potash, soda, lime, magnesia, sulphuric and muriatic acids, tea/er, Polyhallite. Both potash and soda are largely employed in the making of glass and soaps. When pure they are not easily dis- tinguished from each other, but potash is the heaviest. Until lately, both potash and soda were believed to be simple substances, but by the experiments conducted by Sir H. Davy, with the astonishing powers of electro-chemi- cal agency, they have both, as w T ell as the earths, been actually decomposed. The mode by which this was effected is highly ingenious and interesting ; the detail belongs to the chemist. The result however was, that potash was found to be a combination of oxygen with a substance re- sembling quicksilver in appearance, and which by the dis- coverer has been called Potassium^ as being the basis of potash. The result was exactly similar in regard to soda, the basis of which is called Sodium. Both Sodium and Potassium possess a close affinity to some of the metals ; they are malleable, and in this respect agree in character with iron, copper, and some other metals. Both potash and soda are by some chemists considered to be metallic oxides. Nevertheless potash and soda still hold their rank as alkalies. It is by no means improbable that future researches in chemistry will also discover the nature of the bases of all the substances now ranked as earths, some of which are Of the Alkalies. 07 yet unknown, and that by common consent, the substances called the earths, and those termed fixed alkalies \vill bo swept away, and their bases added to the catalogue of metals : this has already been done by some chemists. Li I hi a. Lithia is but of late discovery ; and it has been already found by experiment not to be a simple elementary body, but a compound, consisting in the 100 parts, of about 57 of Lithium^ and about 43 of oxygen. , It has an acrid caustic taste, and is very soluble in water. The metallic base of this alkali, Lithium^ has been pro- cured by the chemist, and observed to be of a white colour, and very similar to sodium, but it soon absorbed the oxy- gen of the air from exposure to it, and was thereby shortly again converted into Lithia. It has been found only in a very few minerals, in a pro- portion not equal to 10 per cent. Lithia* silex, alumine, constitute Petalite, Spodumene. Lithia, potash, silex, alumine. Tourmaline, Lepidolite. LUlua, soda, silex, alumine, lime, Meionite. Lithia, alumine, phosphoric acid, fluoric acid, Amblygonite. Ammonia. Volatile Alkali, or Ammonia, 'when pure, subsists only in a gaseous form. It consists of hydrogen and nitrogen, in the proportion of about 2 of the former, and 98 of the latter. Volatile alkali is found only in combination with the sulphuric and muriatic acids, forming sulphate and muriate of ammonia. The former is found in certain lakes in Tuscany. Muriate of ammonia, also called sal ammo- niac, is chiefly found in the crevices of the lavas of JEtna. and Vesuvius, and in coal. Ammonia, sulphuric acid, Sulphate of Ammonia. Ammonia, muriatic acid, Muriate of Ammonia. The discoveries above detailed of the bases of the Earths and Alkalies, were effected by the aid of galvanism super- 28 Of Selenium. added to chemistry. Galvanism or electricity therefore (for a doubt of their identity scarcely exists) holds a high and important station in science. With such aid, chemi- cal experiment, conducted by such men as Sir H. Davy, may work a complete reformation in science : it is impossible even to conjecture where discovery will stop. Selenium. We shall now give some attention to Selenium, of which the nature does not yet appear to have been accurately determined. It is of a grey colour, and brilliant metallic lustre, and possesses a very slight degree of translucency. It melts at a temperature a little above boiling water, and evaporates in close vessels at a temperature a little below redness ; when cooling it is ductile, may be kneaded be- tween the fingers, and drawn out into fine threads, having a strong metallic lustre. When slowly cooled, it has a granular fracture, and resembles cobalt. Before the blow- pipe it volatilizes, giving out a strong scent of horse-radish, with which one-sixteenth of a grain suffices to fill a large apartment. It is commonly ranked among combustibles : some che- mists seems to think it ought to rank among the metals ; but it is a bad conductor of ealoric, and is a non-conductor of electricity. It was first discovered by Berzelius in the reddish masses, chiefly consisting of sulphur, deposited in the chambers for making sulphuric acid from the sulphur procured from Fahlun in Sweden, and exists in the iron pyrites of that neighbourhood, from which the sulphur is obtained. It has also been found in the iron-pyrites of our own country. It forms also an ingredient of the following compounds, in small quantity ; and though at present considered to be a scarce metal, it will hereafter probably be found more abun- dantly involved in the iron pyrites of different countries. Selenium and copper constitute Seleniuret of Copper. Selenium, copper, silver, Seleniuret of Copper and Silver. ' ' LECTURE II. Of the Metals Of Combustibles. ON a former evening it was said that mineral substances are considered to be of four kinds, EARTHY, ALKALINE METALLIC, and COMBUSTIBLE. That they are naturally found either simple or compound : the simple consisting of one substance alone ; the com- pound of two or more ; and that these are either mechani- cally or chemically combined. That some of the earths and metals are found combined with various acids ; and some of the metals with oxygen ? or the basis of vital air. It was also said that by the aid of chemistry, ten earths had been discovered, and four alkalies ; but that Sir H. Davy, by the assistance of electro-chemical agency, had lately proved that some of the earths, and some of the alkalies, are compounds, having bases which in some of their properties are nearly allied to the metals ; and that they consist of oxygen in combination with those bases. But as the nature of the bases of several of the earths and of the alkalies, have not yet been determined with pre- cision, and as such of the bases as are best known, do not in all respects agree with, although they approach the metals in character, it will be most advantageous in the present state of our knowledge, still to consider these sub- stances as earths and as alkalies, rather than as metallic oxides. Having also in the former evening considered the nature and some of the properties of the earths and alkalies as mineral constituents, we shall now proceed to notice the metallic bodies, and afterwards those substances which are called combustibles. 30 Of the Metal*. OF THE METALS. The only metals known to the ancients were gold, silver, copper, iron, tin, lead, and mercury ; but discoveries have from time to time increased the catalogue, until it has been swelled to the number of twenty-eight, independently of such of the bases of some of the earths and alkalies as may hereafter be found to agree in characters with the metals. Of these metals twelve only have the important property of malleability, or of being sufficiently tenacious to bear the extension of their body by beating with the hammer ; the others have by some been therefore termed brittle metals, Malleable Metals, Brittle Metals. Platina, Arsenic, Molybdena, Gold, Antimony, Tungsten, Silver, Bismuth^ Chrome, Quicksilver, Cobalt, Osmium, Lead, Manganese^ Iridium, Copper ) Tellurium, Rhodium, Tin, Titanium, Uranium, Iron, Columbium, Cerium. Zinc, Palladium) Nickel, Cadmium. A lustre is peculiar to the metals, which therefore is called the metallic lustre : another remarkable property is their want of transparency when in the mass ; but as leaf gold, which may be beaten into leaves so thin that they will float in the air like a feather, when held between the eye and a luminous body, transmits a green light, and silver a white light, it seems probable that other metals, if at- tenuated in the same degree, would also be translucent. In weight, the foregoing metals far exceed the earths ; the heaviest of the earths is only about four times heavier Of the Metuli. 31 than water, but the lightest of the metals is more than six times heavier than water. Beaten gold is nineteen times heavier than water, and beaten platina, the heaviest of all, is twenty-three times heavier than water. The characters of fusibility and extensibility in metals is of vast importance to man ; for without these characters neither could they be freed from the earths and other im- purities with which they are naturally found, nor wrought into vessels for his use. . Metals are believed to be simple substances : not one of them has hitherto been decomposed. The only metals that as yet have been found in the metallic state, are platina, gold, silver, quicksilver, copper, antimony, arsenic, tellurium, bismuth and iron ; whence, when so found, they are termed native metals, or are said to be in the native state. But the greater part of these are rarely found quite pure, but mostly contain small propor- tions of other metals, intermixed. It deserves notice that seven of the malleable metals, zinc, tin, lead, iron, copper, nickel, and quicksilver, absorb oxygen from the common air, especially when moist, be- coming at least externally oxidated : none of them part with the oxygen by simple exposure to heat, except quicksilver. Gold, silver and platina only become oxidated by exposure to the action of certain acids. But although the greater part of the malleable metals are readily oxidable, not one of them has yet been found in, or converted into, the state of an acid. All the brittle metals absorb oxygen by exposure to com- mon air, and thus become, at least externally, oxidated. Five of them, arsenic, chrome, molybdena, tungsten and columbium, by an excess of oxidation, pass into the state of acids, and in this state they are found to be the mine- r.alizers of some of the earths and of the metals. The metals and metalliferous ores are chiefly found in veins, of which they occasionally compose the only sub- stance ; but they are more often disseminated in veins,, through earthy or stony substances : such a substance is 32 Of the Metals. termed the gangue or matrix of the ore. Metalliferous ores are less commonly found in masses or in beds : a few of them occasionally occur imbedded in certain rocks* They are met with in veins traversing almost every kind of rock, but are more common in primitive and transition rocks, than in floetz rocks : they occur but sparingly in alluvial deposits, and more rarely in volcanic matter. But the quantity of each metal found in the native or metallic 3tate is generally very small ; except in the case of gold, which is mostly in that state. The immense quan- tities of some of the metals brought to light annually by the industry of man for the purposes of convenience or of luxury, are procured from compounds, in which the metal is intermixed or mineralized by other bodies, and which are termed metalliferous ores. An ore is a compound of two or more metals, or of a metal in combination with oxygen ; (whence such a com- bination has obtained the name of a metallic oxide ;) or a metal (in the state of an oxide) combined with an acid or, a metal combined with a combustible. Many ores are of so compound a nature as to consist of two or three metals united with oxygen, sulphur, one or more of the earths, and with water. We will now give attention to the metals individually ; beginning with those which possess the qualities of fusi- bility, ductility, and malleability, so important to man. JPlatina. Platina is about twenty-three times heavier than water ; it is of a colour between steel-grey and silver-white ; hitherto it has only been found in Peru, Brasil, and in the island of St. Domingo. In Peru, it is found in little flat- tened grains, rarely exceeding the size of a pea, accom- panied by gold, magnetic iron sand, and minute hyacinths; yet it is said that Humboldt presented the King of Prussia with a mass larger than a pigeon's egg. But the grains of Of the Metals. 33 crude or native platina are not pure ; analysis has proved them to consist of platina alloyed by seven other metals, osmium, iridium, rhodium, palladium, iron, copper and lead, which will hereafter be noticed. The platina of Brazil is alloyed by gold and palladium. That of St. Domingo has not been analyzed ; it is accompanied by magnetic iron and gold. Platina is found only native, alloyed by other metals. Crude platina is very difficult of fusion. Pure platina in thin plates is very ductile and flexible. Of late it has been formed into mirrors for reflecting telescopes, spoons, cru- cibles, and some vessels of considerable dimension for the use of the chemist in particular processes. So ductile is platina, that Dr. Wollaston has succeeded in drawing it into a wire the 18,750th part of an inch in diameter, which will support about 1^ of a grain without breaking. Gold. Gold, when pure and beaten, is about nineteen times heavier than water ; it is very soft, and perfectly ductile and flexible. So great is the tenacity of gold, that a piece one-tenth of an inch in diameter, will hold five hundred pounds without breaking ; and it is computed that a single grain of gold will cover the space of fifty-six square inches, when beaten out to its greatest extent ; and in that state it is only the 280,000th part of an inch in thickness. Gold is always found in the metallic form, whence, by mineralogists it is said to occur in the native state ; but it is generally alloyed by small portions of other metals, as silver, copper, &c. It has never been found mineralized by sulphur or by an acid. It occurs in mineral veins in pri- mitive mountains but not of the oldest formation : it is thus found in Brazil, Peru, Mexico, Hungary and Transylvania. It is sometimes accompanied by quartz, felspar, carbonate of lime, sulphate of barytes, and some of the ores of silver, cobalt, manganese and nickel ; and when regularly crystal- lized, assumes forms of perfect geometrical regularity. It 34 Of the Metals. is occasionally contained in the ores of other metals in small proportion, as those of arsenic, lead, iron, copper, &c or is accompanied by them. Sometimes gold is crystallized in small cubes and regular octohedrons ; and as these crystals cannot be broken in any particular direction, either of those solids may be taken as the form of the primary -crystal of gold. Gold is found pure or native. Gold and silver form Electrum. Gold is sometimes found in iron pyrites, and occurs as an alloy in the ores of tellurium, silver, &c. Helms says, that when a projecting part of one of the highest mountains in Paraguay fell down, about forty years ago, pieces of gold, weighing from two to lifty pounds each, were found in it ; and that in the Vice-royalty of La Plata alone, there are thirty gold mines. The annual produce of America, is about 30,000 pounds weight. A great quantity of gold is obtained in grains and rounded masses in soils, evidently the ruin of rocks which contained it in its natural situation. In this state it has been found in Wicklow in Ireland, and in Cornwall, in small quan- tities. A few years ago a single specimen of gold, equal in weight to upwards of ten guineas, was found amongst tin in a stream-work in Cornwall. On the coast of California there is a plain of fourteen leagues in extent, about fourteen inches beneath the surface of which it is said that large lumps of gold are irregularly interspersed. But a still greater quantity of gold has been obtained in the form of a fine sand, from the Peruvian, Mexican and Brazilian rivers, and from some of the African. In Europe, the Danube, the Rhine, and the Rhone, and the streams of Hungary and Transylvania, afford small quantities. The uses of gold are well known. Alloyed by copper, it is employed for ornamental purposes, coin, and plate. In English coin it is alloyed by two parts of copper to twenty-two of gold ; that now used in plate is 18 carats, or l^ths gld. The purple colour used in porcelain paint- ing is obtained from a preparation of gold. Of the Metals. 35 Silver. Silver, when pure is ten times heavier than water, and i soft, opaque and flexible ; a piece one-tenth of an inch in diameter will support two hundred and seventy pounds without breaking. Silver occurs in the metallic or native state ; but is some- times alloyed by a small proportion of gold, sometimes of copper. It is found in fine filaments disseminated through rocks, but chiefly in veins, in primitive and secondary mountains ; occasionally it occurs crystallized in cubes and regular octohedrons, and is accompanied by calcareous and other spars, iron pyrites, cobalt, and some other sub- stances. It is found in Peru, Mexico, Saxony, Bohemia, Norway, Hungary, and England ; but the mines of the two former furnish annually ten times more silver than all the mines of Europe united. The ores of silver are numerous ; for although it mostly occurs in the pure state, it is also found combined with gold, copper, antimony, iron, lead, bismuth, arsenic ; with the earths, silex and alumine, and mineralized by the muriatic and carbonic acids^ and by sulphur. Silver is found pure or native. Silver and antimony constitute Amimonial Silver. Silver, molybdena, Molybdic Silver. Silver, sulphur, Stilphuret of Silver. Silver, sulphur, iron, Flexible Sulphuret of Silver. Silver, sulphur, antimony, iron, Brittle Sulphuret of Silver, Sulphuret of Silver, and Antimony, Silver, sulphur, antimony, oxygen, Red Silver. Silver, sulphur, copper, Sulphuret of Silver and Copper. Silver, sulphur, antimony, lead, fyc. White Silver. ' Silver, sulphur, bismuth, lead. Bismuthic Silver. . Silver, carbonic acid, antimony, fyc. Carbonate of Silver. Silver, muriatic acid, Muriate of Silyer. Galena, or the sulphuret of lead, the most common of its ores, mostly contains some portion of silver, but not always worth extracting. The lead of the Westmoreland and Cum- berland mines yields an average of seventeen ounces of E2 36 Of the Metals. silver to the ton of lead ore. The Beeralston mines in Devonshire yielded about eighty ounces. The richest par- haps ever known, was that found at Brunghill Moor, in Yorkshire, which yielded two hundred and thirty ounces to the ton. According to Helms, the mine of Yauricocha, in Peru, which is about 13 5 000 feet above the sea, contains a pro- digious vein of porous brown iron-stone, half a mile wide, interspersed throughout with pure silver; a white argil- laceous vein runs through it which is very much richer. It is asserted that Yauricocha, and the mines of the district surrounding it, have yielded forty millions of dollars in a year. It is said that in 1750, a mass of silver was found in a mine near Frey burg in Saxony, weighing upwards of 1401bs. and another of about the same size in 1771. In the year 1748, a block of native silver and silver ore was cut out in a rich vein of silver, near Schneeberg ; Duke Albert of Saxony descended the mine, and used it at a dinner table. When this huge block was smelted, it yielded 44,000 Ibs. of silver. We are told that Annibal received 300 pounds weight of silver, daily, from the mines near Carthagena in Spain. The uses of silver are numerous, and for the most part obvious. In coin, silver is alloyed by one part of copper to fifteen of silver. The yellow colour used in porcelain painting is oxide of silver. Quicksilver. Mercury or Quicksilver, is thirteen times heavier than water, and is fluid in the natural temperature of the atmos- phere, sufficiently distinguishing it from all the other metals. It mostly occurs in the native state (but sometimes con- tains a little silver) disseminated in globules, or collected in the cavities of its mines, which are most commonly situated in calcareous rocks, or indurated clay, or argil- laceous schistus. Of the Metals. 37 Quicksilver mines are worked in Carniola, the Duchy of Deux-ponts, Spain and Peru. The vein of Guancavelica in South America, in which quicksilver is found in the state of cinnabar, is 80 Spanish ells in extent, and is situ- ated partly in sandstone, partly in limestone. The cinnabar is accompanied by the sulphuret of lead, calcareous spar, barytes, manganese, arsenic, &c. The quicksilver mines of Idria, in Saxony, are said to yield 100 tons annually, and those of Spain a still greater quantity. The mines of Peru are said to be still richer. The ores of mercury are not numerous : combined with silver it is called native amalgam, with sulphur and iron, cinnabar. Horn quicksilver is a natural combination of mercury, in the state of an oxide, mineralized by the sul- phuric acidy and of mercury, also in the state of an oxide, mineralized by the muriatic acid. Quicksilver is found pure or native. Quicksilver and silver form a Native Amalgam. Quicksilver, sulphur, Cinnabar. Quicksilver, oxygen, muriatic and sulphuric acids, Horn Quicksilver. The uses of mercury in medicine, in the arts, and in experimental philosophy are numerous ; but its chief use is in the separation of gold and silver from their ores, by a process called amalgamation. When amalgamated with tin, and laid on glass, it forms mirrors. Lead. Lead when pure, is more than eleven times heavier than water ; a piece one-tenth of an inch in diameter, will hold twenty-nine pounds without breaking. It is not elastic. Lead has never yet been found in the native state. Its ores are numerous, the most common of them occur in beds or veins in almost every mineral district in the known world, and are perhaps next to some of the ores of iron, the most common of metalliferous ores. The mines of lead are chiefly situated in secondary countries; its ores are not very common in those termed primitive. 38 Of the Metals. Lead is found in combination with other metals, as cop- per, antimony, manganese, and silver ; and the earths, silex, alumine, magnesia, and lime. It is found, in the state of an oxide, and sometimes also in that state, mineralized by the carbonic, muriatic, phosphoric, arsenic, molybdic, sulphuric, chromic, and tungstic acids ; which cause it to lose every appearance and character of lead. When thus mineralized, it is frequently transparent, or translucent, and has the appearance of an earthy mineral, but the ores of lead may generally be told by their weight, which is mostly superior to the heaviest of the earthy minerals, the carbonate and sulphate of barytes. Many of its ores have not been analyzed. J^ead and sulphur constitute Galena. Lead, antimony, copper, sulphur, Bournonite. Lead, oxygen, Native Minium. Lead, oxygeji, alumine, water, Plombgomme. Lead, oxygen, carbonic acid, water, Carbonate of Lead. Lead, oxygen, carbonic and sulphuric acids, Sulphate-carbonate of Lead, Sulphato-tri-carbonate of Lead,. Lead? oxygen, carbonic and sulphuric acids, copper, Cupreous Sulphato-carbonate of Lead. Lead, oxygen, muriatic and carbonic acids, Murio-carbonate of Lead, Lead, oxygen, phosphoric and muriatic acids, Phosphate of Lead. Lead, oxygen, arsenic and muriatic acids, Arseniate of Lead. Lead, oxygen, sulphuric acid, water, Sulphate of Lead. Lead, oxygen, sulphuric acid, copper, Cupreous Sulphate of Lead. Lead, oxygen, molybdic acid, Molybdate of Lead. Lead, oxygen, chromic acid, Chromate of Lead. Lead, copper, oxygen, chromic acid, Vauquelinite. Lead, oxygen, tungstic acid, Tungstate of Lead. Galena, the most common of the ores of lead, is by far of the greatest importance to man, because from it are prin- cipally derived the immense quantities of lead for his use : it mostly contains some silver. It occurs in large beds and veins in primitive or secondary mountains, most abundantly in argillaceous schistus and secondary limestone, and is accompanied by the ores of zinc, copper, iron, silver, andf by quartz, sulphate of barytes, and the carbonate and fluale Of the Metals. 39 of lime. It is sometimes compact, sometimes crystallized in the cube and regular octohedron. It would scarcely be possible to enumerate all the valu- able purposes to which lead is applied in the arts, in medi- cine, and in the common wants of man. Among its less obvious uses, lead is employed to glaze pottery, and its oxide enters into the composition of glass. Four parts of lead and one of antimony form printing types, to which by some is added a little copper or brass. With tin and bis- muth it forms alloys mentioned in the notice of those metals. Copper. Copper in its pure state, is about eight times heavier than water; it is so tenacious that a wire one-tenth of an inch in diameter will support two hundred and ninety-nine pounds and a half without breaking. It is a very malleable and ductile metal, of a pr>le red colour, with a tinge of yellow. In the natural stale it occurs very pure ; and its ores are very numerous. In both states it is found in almost every mineral district in the world, in beds, or more commonly in veins, in primitive and secondary mountains, accompanied by several other mineral substances, as the ores of zinc, and occasionally of lead, sometimes of tin, silver, and arsenic ; with quartz and fluate of lime and calcareous spar in abundance. Native copper is not however found either in beds or veins in great quantities; it is met with in Cornwall, the JIartz, Saxony, Sweden, and in America; that of Japan and that of Brazil are alloyed by gold. A mass of native copper is said to have been found in a valley in Brazil weighing 2666 Portuguese pounds. Wherever found, it is of various shapes ; sometimes it is crystallized in the cube and regular octohedron : and is commonly accompanied by quartz, heavy spar, and calcareous spar, except in Corn- wall, where the two latter are rarely seen. Mineralized by a certain proportion of oxygen^ it forms a beautiful mineral called the red oxide of copper, which 40 Of the Metals. assumes a great variety of forms, all of which may be traced into the regular octohedron ; with an increased proportion of oxygen, it assumes a black hue and is mostly pulverulent. Copper is found combined with iron, antimony, silver, and arsenic, with lime and silex, and mineralized by the phosphoric, carbonic, arsenic, sulphuric, and muriatic acids, and by sulphur, which cause it to lose all metallic character and appearance. It is not a common ingredient in the ores of other metals. Copper is found pure or Native. Copper, sulphur, constitute Vitreous Copper. Copper, sulphur, 8$c, Buntkupfererz. Copper, sulphur, iron, Grey Copper, Copper Pyrites. Copper, arsenic, iron, sulphur, Tennantite. Copper, oxygen, Red Copper, Black Copper. Copper, oxygen, carbonic acid, water, Blue Carbonate of Copper. Green Carbonate of Copper. Copper, oxygen, carbonic acid, silex, Chrysocolla. Copper, oxygen, carbonic add, lime, Dioptase. Copper, oxygen, muriatic acid, water, Muriate of Copper. Copper, oxygen, phosphoric acid, Phosphate of Copper. Copper, oxygen, phosphoric acid, water, Hydrous phosphate of Copper. Copper, oxygen, arsenic acid, water, Arseniate of Copper. Copper, oxygen, arsenic acid, iron, Martial Arseniate of Copper. Mines of copper are largely wrought in England, Ger- many, Sweden and Siberia ; those of Spain, France, Hun- gary, Norway and Ireland are much less extensive and numerous. This metal has been found in great quantity also in Asia, Africa and America. The most common copper ore of the Cornish mines is of a yellow colour, and is called yellow copper ore, or copper pyrites ; analysis proves it to consist of copper, iron ; and sulphur in nearly equal proportions. The uses of copper in all its various states are almost endless, and only, if at all, inferior to those of iron. Alloyed with certain proportions of zinc, it forms brass, pinchbeck, tinsel, and Dutch gold, in imitation of gold leaf. With a small proportion of tin, copper forms bronze or bell metal; but if the proportion of tin amount to one third, it forms Of the Metals. 41 speculum metcil, used for reflecting telescopes. With zinc and iron, it forms tutenag. In porcelain painting, the green is obtained from copper. Tin. Tin, in its pure state, is about seven times heavier than water, but has never been found pure. In the common ore of tin mines, it is always in combination with oxygen, whence it is termed an oxide, and in this state it is some- times so nearly colourless and transparent, as to lose all appearance of a metallic substance ; but analysis proves that the dark and opaque crystals contain small portions of iron and of silex. The form of the primary crystal is a flat octohedron, which however is in general greatly altered in appearance t by the planes of the several modifications to which it is subject ; so that the crystals of the oxide of tin assume at least 150 varieties of form. In one or two places in Cornwall an ore has been found called sulphur et of tin, or bell metal ore (from its resem- blance to that metal in colour), which consists of tin, cop- per, and sulphur, together with a small portion of iron. Tin and oxygen constitute Oxide of Tin. Tin? copper, iron, sulphur, Sulphuret of Tin. A variety of the oxide of tin, called wood tin, from its occasional resemblance to wood, is found sparingly in two or three places in Cornwall only. Tin is considered to be one of the oldest metals, because it is principally found in the most ancient of those rocks which, from their not containing any animal or vegetable remains, are termed primitive. It occurs disseminated in them, and in beds, but principally in veins, mostly in a state of crystallization, being rarely compact ; and is frequently accompanied by the oies of tungsten, arsenic, iron, copper and zinc, and also by quartz, mica, fluate of lime, topaz, and some other substances. The tin veins of Cornwall are found passing through granite and argillaceous schistus. Minute crystals of tin are sometimes found disseminated in the former rock ; and hence, as granite is commonly F 42 Of the Metals. esteemed to be the most ancient of all rocks, tin is con- sidered to be one of the oldest metals. The ore of tin is also abundantly found in Cornwall, in rounded portions or grains, in what may be termed diluvial beds; that is, in depositions which have resulted from the ruin of rocks. Tin is by no means one of the most commonly diffused metals. It is most abundant in Cormvall and the western part of Devonshire ; but it is also found in Gallicia, in Spain, in Saxony, in Bohemia, in Malacca and Banca in Asia, and in Chili in South America. Two or three small veins have lately been discovered in France. When pure, it is of a whitish colour, approaching that of silver ; it is harder, more ductile, and more tenacious than lead, and is very fusible. It is the lightest of the ductile metals ; most probably because in cooling after fusion, it has a great tendency to crystallize, so that the mass con- sists of innumerable small plates or crystals intercepting each other in every direction, with hollow spaces between them ; and owing probably to this circumstance, it gives out a peculiar crackling noise when bending : it is scarcely or not at all elastic. Though not one of the most ductile of metals, tin may be beaten into leaves the 1000th part of an inch in thickness. The alloys of tin with other metals are mentioned in treating of lead, copper, and quicksilver. Another will be noticed under the article bismuth. In the fine leaf constituting tin foil, it is used for many purposes ; its salts are used in dyeing : its economical purposes are well known.* * Of Tin there are two sorts, common tin and grain tin : common tin is derived from the tin found in veins, where it is mingled with other substances, as iron, arsenic, &c. and when reduced to the metallic state is more or less intermingled with these substances ; it is therefore in an impure state. Grain tin, on the contrary, is chiefly obtained from the ore of the stream-works of Cornwall, which are deposits of ore consist- ing of separate crystals of oxide of tin, more or less rounded by attrition, and deposited in low grounds by the action of water on the surface of the earth, which destroyed the rock, and left the heavier metal. Three parts of tin, seven of bismuth, and five of lead, form an alloy which melts in boiling water. Of the Metals. 43 Iron. Iron, when cast, is about seven times, but when ham- mered is nearer eight times, heavier than water ; it is per- haps the most universally diffused substance in nature, being found in all soils, and in almost every rock. It is said to have been found in two or three places in the metallic or native state, alloyed by small proportions of lead and copper. But considerable masses of a substance, which by some is termed native meteoric iron, have been found in different quarters of the globe ; in Bohemia, in Senegal, in South America, and in Siberia ; of the latter we have the best account. It was found by professor Pallas on the top of a mountain, on which there was a considerable bed of mag- netic iron-stone, on the banks of the river Jenisei. It weighed 1680 Russian pounds, and possessed some of the important characters of pure iron, as malleability and flexi- bility, and was reported by the inhabitants of the country to have fallen from the sky. The mass found in the Vice- royalty of Peru in South America, was described by Don Rubin de Celis : it weighed about fifteen tons ; it was compact externally, and was marked with impressions as if of hands and feet, but much larger, and of the claws of birds ; internally it presented many cavities : it was nearly imbedded in white clay, and the country round it was quite flat and destitute of water. The above mentioned and other masses of iron, which from a current belief of their having fallen from the sky, have also obtained the names of meteoric iron^ have been subjected to analysis, and in each the iron has been found alloyed with more than one-tenth of the rare metal called nickel ; which also, it is worthy of remark, is found by analysis to be a constituent part of all those stones, which in various parts of the European continent, in England, and in America, have been known to fall from the atmosphere, and are therefore termed meteoric stones. The ores of iron are numerous, and arc found in beds, in 44 Of the Metals. veins, and disseminated in rocks. Iron occurs combined with the oxides of titanium, chrome, and other metals, with carbonate of lime , silex, alumine, and sulphur ; and with the phosphoric, sulphuric., carbonic, arsenic, chromic, and oxalic acids; but except when combined with sulphur, iron is always united with oxygen. An ore, in which iron is com- bined with alumine, is used in the making of what are termed read lead pencils. Plumbago, or black lead, is a natural compound of iron, with a large proportion of carbon. Iron has been found pure, or native. Iron and arsenic constitute Mispickel. Iron, sulphur, Iron pyrites, White Iron pyrites, Magnetic Iron pyrites. Iron, oxygen, Oxydulated Iron, Specular Iron. Iron, oxygen, zinc, Franklinite. Iron } oxygen, water, Hydrous Oxide of Iron Black Iron ore Red Iron ore Jaspery Iron ore- Brown Iron ore Iron, oxygen, manganese, phosphoric acid, fyc. Bog Iron ore. Iron, oxygen, sulphuric acid, $c. Pitchy Iron ore. Iron, oxygen, muriatic acid, $fc. Pyrosrnalite. Iron, carbonic acid, Spathose Iron, Clay Iron stone. Iron, phosphoric acid, Phosphate of Iron. Iron, sulphuric acid, Green Vitriol. Iron, chromic acid, Chromate of Iron. Iron, arsenic acid, icater, Arseniate of Iron. Jron, oxalic acid, Oxalate of Iron. In the most common and plentiful iron ore of the English mines, which is found in layers in slaty clay between the beds of coal, the iron is in the state of carbonate, inter- mixed with the argillaceous and siliceous earths. The oxide of iron, which from its magnetical properties is, termed Magnetical Iron Ore, is found in abundance at Roslagia in Sweden, and is converted into the best bar iron, so much prized by our manufacturers of steel. Pure iron is of a bluish grey colour, has a granular tex- ture, and is the most tenacious of the metals next to gold. It is more ductile than either gold or silver, for it may be drawn into wire as fine as the human hair ; so great is its- tenacity, that a wire less than l-10th of an inch in diameter Oj the Metals. 45 will bear the weight of 550 Ibs. without breaking. When exposed to the atmosphere, it absorbs oxygen and becomes an oxide, or, in common language, rusts. It is highly magnetic, and so readily acquires polarity, that if a bar of iron be left a long time in a vertical position, the northern pole will be found to be at the lower extremity. It would be vain to attempt the enumeration of the uses to which iron is put by man. Steel is an artificial com- bination of iron with carbon. The brown colour used in porcelain painting is oxide of iron.* Zinc. Zinc, when pure, is about seven times heavier than water ; its tenacity is not great ; a piece one-tenth of an inch in diameter will hold twenty-six pounds without breaking ; and being far less ductile than some other metals, its importance is thereby diminished. Zinc is never found in the pure, or native state ; its ores are not very numerous, and of these some varieties are found. Zinc as an oxide, combined with carbonic acid, forms a most abundant ore, called calamine ; and the oxide of zinc, united with the sulphuric acid, is found in small efflorescences termed sulphate of zinc. Zinc as an oxide, combined with silex, forms electric calamine, so termed from its becoming electric when slightly heated. Zinc combined with iron, sulphur, silex, and water, forms the ore called blende ; a variety of which on being scratched emits a phosphoric light. It occurs massive, and also in a great variety of crystalline forms ; the primary of which is considered to be the rhomboidal dodecahedron, into * After iron has been run down in the furnace from the ore, it is suffered to flow through a channel of sand into moulds; and in this state: it is termed cast-iron, of which stoves, pipes, &c. are made more cheaply than of hammered iron. To render iron ductile and malleable, it is again melted and kneaded in the furnace, afterwards hammered and forged into plates and bars, and in this state is termed bar or hammered ^ron. Iron is converted into steel by being exposed to the action of heat in contact with carbonaceous matter, which penetrates its substance, and is tempered when red hot by plunging it into water, by which it becomes harder, move elastic, and brittle. 46 Of the Metalt. which the perfectly laminated varieties of this mineral may be readily split; as well as into three or four solids of other forms. Zinc and sulphur constitute Blende. Zinc, oxygen, manganese, Red Oxide of Zinc. Zinc, oxygen, silex, water, Siliceous Oxide of Zinc. Zinc, oxygen, carbonic acid, Calamine. Zinc, oxygen, sulphuric* acid, White Vitriol. The ores of zinc are found in most mineral countries ; most abundantly in the transition or earlier secondary rocks, accompanied by iron pyrites, native silver, sulphuret of lead, some of the ores of silver, and by calcareous spar, quartz, and sulphate of barytes. Zinc, the Spelter of commerce, is a bluish-grey metal. It is employed by the Chinese for coins ; it enters into the composition of many alloys. It is sometimes used in medi- cine, and in oil painting. Palladium. Palladium is about eleven times heavier than water ; it is very malleable, and somewhat harder than bar iron. It occurs alloying the native platina of Brazil, which it greatly resembles in colour; and also in little separate grains, apparently composed of diverging fibres, intermingled with those of native platina and very much resembling them : it has never been applied to any use. Palladium is found pure or Native ; and alloying Native Platina. Nickel. Nickel is about nine times heavier than water, and is of a yellowish white. It is attractable by the magnet, though not so readily as iron ; and is ductile, and nearly as malle- able as silver. It has never been found in the pure state : its ores are few ; they have been found in mineral veins and beds in France, Spain, Bohemia, Siberia, and in England sparingly; they are generally accompanied by the ores of silver, cop- per, and cobalt, by calcareous spar and quartz, and by Of tht Metals. 47 some other substances. It occurs combined with arsenic, and other metals. Nickel is found pure or Native. Nickel, arsenic, fyc. constitute Arsenical Nickel. Nickel, oxygen, arsenious ci'd, Nickel Ochre. Nickel, oxygen, silex, Pimelite. It is remarkable that nickel, which is one of the least abundant metals, has been found by analysis to enter into the composition of these stony and metallic substances which in various parts of Europe and America, have fallen from the atmosphere; whence they are termed meteoric stones and meteoric iron. Nickel has not been applied to any use ; hence no at- tempt has been made, in the large way, to reduce its ores. Cadmium. Cadmium resembles tin in colour, lustre, softness, duc- tility, and in the sound it emits when bent, and has been obtained in thin plates, but it melts and volatilizes at a temperature a few degrees below that required by tin. It is about eight times the weight of water, and was first dis- covered in the oxide of zinc prepared for medicinal use, from an ore of zinc found in Silesia, and has since been found in some of the ores of that metal in England. We have now taken a slight view of the twelve metals which have been termed perfect, on account of their pos- sessing the valuable properties of fusibility , ductility, and malleability. I now proceed to those which, not possessing the two latter properties, have been by some termed the brittle, or semi-metals. Arsenic. Arsenic, when pure, is rather more than eight times heavier than w r ater, and is of a bluish white colour, and possess a brilliancy not unlike that of polished steel ; but by exposure to air it absorbs oxygen, the surface becomes 48 Of the Metals. oxidated and nearly black. When exposed to heat, or struck by a hammer, it gives out the odour of garlic, and by this means its presence may sometimes be detected. It is found nearly pure, being alloyed only by small por- tions of iron and sometimes of gold or silver, chiefly in primitive mountains, in veins_, accompanied by some ores of silver, cobalt and lead ; by calcareous spar, fluate of lime, and quartz^ and some other minerals. Native arsenic is principally found in certain districts of Germany, but is found in other mining countries, in small masses, never crystallized. Combined with oxygen, it occurs in small crystals in certain mines of Hesse, Saxony, and Hungary ; and as an efflorescence in the fissures of certain lavas. Arsenic, combined principally with iron, forms a mineral called arsenical pyrites, or mispickel ; in some of the va- rieties of which silver is found. This ore principally occurs in veins in primitive mountains. It is common in the tin and copper mines of Cornwall. Arsenic also occurs combined with twenty-five parts of sulphur, forming an ore of a red or orange colour, called Realgar ; and with forty-three parts of sulphur, it forms an ore of a bright lemon yellow colour, called Orpiment. Realgar is said to occur principally in primitive mountains; orpiment principally in floetz or secondary rocks. These minerals are sometimes found massive, sometimes though rarely crystallized ; and they occur in the primitive moun- tains of Switzerland, Saxony, &c. and near the volcanoes of jEtna, Vesuvius, &c. Orpiment and realgar are used as pigments. Arsenic is found pure or Native. Arsenic and oxygen constitute Oxide of Arsenic. Arsenic, sulphur, Realgar, Orpiment. Arsenic is one of the least useful metals, and though a poison, is used in medicine ; it is also used in the making of glass. Of the Metals. 49 Antimony. Antimony is a compact, brittle, bluish white metal, be- tween six and seven times heavier than water. It is found nearly pure, being alloyed only by very small portions of silver and iron. Native or pure antimony is found in veins in the mountains of Dauphine, in the Hartz, &c. and in Sweden, disseminated in calcareous spar. The ores of antimony are not numerous : this metal occurs mineralized by sulphur and by oxygen ; its ores are found principally in veins in primitive, and .in transition or the older secondary, mountains in Sweden, Saxony, France, Bohemia, England, and other mineral countries occasionally accompanied by heavy, calcareous, and fluor spar, &c. They also occur disseminated in beds, Antimony is found nearly pure or Native. Antimony and sulphur constitute Sulphuret of Antimony. Antimony, oxygen, White Antimony, Antimonial Ochre. Antimony, oxygen, sulphur, Red Antimony. Antimony forms alloys with other metals, and is used in the arts. It enters largely into the composition of printing types ; it is also used in medicine, Bismuth. Bismuth is nearly ten times heavier than water ; it is of a reddish-white colour, and very brittle and fusible. It is found in the native state somewhat alloyed by arsenic or cobalt, either massive, dendritical, or in the form of the regular octohedron. The ores of bismuth are but few ; in that called sulphuret of bismuth, it is combined with sulphur ; in another, called bismuth ochre^ it is mineralized by oxygen^ and includes a small portion of oxide of iron. It also occurs mineralized by the carbonic acid. Bismuth is found pure or Native. Bismuth, sulphur, Sulphuret of Bismuth. Bismuth, oxygen, Bismuth Ochre. Bismuth, carbonic acirf, Carbonate of Bismuth. 50. Of the Metals. Bismuth occurs combined with lead, copper, nickel, tellurium, and sulphur. Native bismuth is rare, as well as its ores ; these are found in veins, mostly in primitive mountains, accompanied by the ores of cobalt, of iron, of zinc, and sometimes of silver; and by quartz, calcareous spar, and barytes, in Bohemia, Transylvania, France, and Sweden. The sul- phuret of bismuth has occurred in Cornwall, as well as the oxide. Bismuth is very little used, but its ready fusibility, since it melts before it is red hot, admirably adapts it for the com- position of the soft solders ; it is an ingredient of sym- pathetic ink. It forms alloys with other metals. The fusible metal of Sir Isaac Newton is composed of eight parts of bismuth, five of lead, and three of tin ; when this is thrown into water, and heat applied, it melts a little before the water has reached the boiling point. Cobalt. Cobalt, when pure, is about eight times heavier than w ater : it is of a grey colour, with a red tinge, and has the magnetic properties of iron : but it is difficult of fusion, brittle, and is easily reduced to powder. It is not found pure in the native state. Its ores are not numerous. In one of them from Tunaberg in Sweden, it is combined with sulphur; in others it is mineralized by arsenic; both much resemble iron pyrites in form and colour. In one place in Hungary, cobalt occurs combined with the sulphuric acid, in stalactites of a pale rose colour. Its other ores have not been analyzed, but in a mineral termed Cobalt bloom, or Arseniate of Cobalt, it is com- bined with the arsenic acid. Cobalt and arsenic constitute Bright White Cobalt. Cobalt, arsenic, iron, Grey Cobalt, Tin White Cobalt. Cobalt, sulphur, Sulphuret of Cobalt. Cobalt, oxygen, Earthy Cobalt. Cobalt, arsenic acid, water, Arseniate of Cobalt. Cobalt^ sulphuric acid, water, Red Vitriol. Of the Metals. 51 The ores of cobalt occur in veins both in primitive and in secondary mountains : they are mostly accompanied by some of the numerous ores of copper, sometimes by native bismuth, native silver, native arsenic, and the ores of silver. Cobalt is very little used except in the arts. It is brought to this country reduced to the state of an oxide, of an intense blue colour, called zaffre, which when melted with three parts of sand and one of potash, forms a blue glass, and when pounded very fine is called smalts, and is then employed to give a blue tinge to writing papers, and in the preparation of cloths, laces, linens, muslins, &c. ; for colouring glass, and for painting blues on porcelain. So intense is the blue of zaffre, that one grain will give a full blue to 240 grains of glass. Manganese. Manganese is of an iron grey colour, and seven times as heavy as water : it is difficult to be obtained in the metallic state : though brittle, it is somewhat malleable, and is not readily fusible. It is never found pure. Its ores are not numerous. It occurs combined with the oxide of iron, with sulphur, with the phosphoric and carbonic acids, and with silex ; but most abundantly with oxygen, as an oxide, of a brown colour or nearly black. Manganese and oxygen constitute Grey Oxide of Manganese. Manganese, oxygen, silex, Helvin, and Black Oxide of Manganese. Manganese, oxygen, iron, silex. Siliciferous Oxide of Manganese. Manganese, silex, iron, carbonic acid, Carbonate of Manganese, and its varieties. Manganese, silex, iron, phosphoric acid, Phosphate of Mangane.se. The ores of manganese are found in various parts of the continent of Europe, and in the mineral districts of Britain ; they occur both in primitive and secondary countries. From the black oxide of manganese, all the oxygen gas used by the chemist is obtained, and all the ,oxygen enter- ing into the composition of the oxymuriatic acid consumed in the bleacheries of Britain, France, and Germany. The G 2 52 Of the Metals. violet colour employed in porcelain painting is obtained from manganese. In glass-making, it is employed in the finer kinds of glass, both as a colouring material and a destroyer of colour : this application of it is ancient ; it is mentioned by Pliny. It belongs perhaps rather to primitive than to secondary countries. Tellurium. Tellurium when pure, is about the colour of tin. It is brittle, nearly as fusible as lead,' and is only about six times heavier than water. It is an extremely rare metal, and is found only in the native state, alloyed by, or combined with, gold and other metals, principally in veins traversing secondary rocks in Transylvania and Siberia. Tellurium is found nearly pure, Native. Tellurium, gold, and silver constitute Graphic Tellurium. Tellurium, gold, silver, lead, Yellow Tellurium. Tellurium, gold, lead, fyc. Black Tellurium. It has never been made any use of. Titanium. Titanium is so difficult of fusion, that the attempts to reduce it to a pure metallic state have scarcely succeeded ; but it occurs in brilliant cubes, which are very small, and of a copper red colour, in the slag of the iron works of Merthyr Tydvil in South Wales. It is about six times heavier than water. It is a rare metal. Two of its ores are said to be nearly pure oxides. In others, titanium occurs in the state of an oxide, in com- bination with oxide of iron^ of uranium., and with silex. They occur sparingly in Hungary, Transylvania, France, Britain, and North and South America ; and only in primi- tive mountains, or their vicinity. The hair-like appearances sometimes to be observed in crystals of quartz, are in most instances crystals of titanium. Of the Metals. 53 An ore of titanium is found in a stream in Cornwall in black grains ; another is found in Transylvania, resembling yellow sand. Titanium, oxygen, constitute Anata^e, Titanite. Titanium, oxygen, silex, C rich ton ite. Titanium, oxygen, silex, lime Sphene. Titanium, oxygen, iron, manganese, Nigrine, Menaccanite. Titanium, oxygen, iron, uranium, Iserine. The only use to which titanium has ever been put, was in the porcelain manufactory at Sevres^ where it was em- ployed to produce the rich browns for painting it. The want of uniformity in colour, ocasioned its disuse. Columbium. Columbium, or Tantalium, is a metal, having but a slight external metallic lustre ; it is of a dark grey colour in- ternally, and is little more than six times the weight of water. In Finland, it occurs as an oxide, combined with iron and manganese, forming a mineral called columbite., imbedded in quartz, in veins that traverse a red granular felspar. In Sweden it is found in a mineral which is called yttrocolum- bite^ because analysis has proved it to be principally com- posed of the rare earth yttria, and the rare metal columbium^ together with some oxide of iron. This mineral occurred in a granitic rock. Columbium, oxygen, iron, manganese, constitute Columbite. Columbium, oxygen, iron, yttria, Yttrocolumbite. It was first discovered in North America, whence the name of Columbium. It is a very rare metal, but has also been found in Finland. Molybdena. Molybdena, when pure, is of a greyish white, and in the form of brittle infusible grains, about eight times heavier than water. It has never been found pure. Combined, in the metallic 54 Of the Metals. state, with sulphur, it occurs in veins in primitive moun- tains in Norway, Sweden, Saxony, Switzerland, and Britain, accompanied by tin, wolfram, quartz, and mica. Molybdena, sulphur, constitute Sulphuret of Molybdena. Molybdena, oxygen, Oxide of Molybdena. The molybdic acid has been found combined with lead, forming a mineral called molybdate of lead, in Carinthia, Saxony, Hungary, and Austria ; it is accompanied by cal- careous spar, sulphuret of lead, the ores of zinc and fluor spar. Molybdena has only been found in small quantities, and has never been applied to any use. Tungsten. Tungsten is a hard, brittle, granular metal, of a light steel-grey colour, and brilliant metallic lustre. It is about seventeen and a half times heavier than water. It is not found pure ; but only in the state of an oxide , or of an acid combined with other substances. The tungstic acid, which consists of 80 parts of tungsten and 20 of oxygen, combined with oxide of iron, and of manganese, forms a mineral called tungstate of iron, or wolfram, which occurs in most districts in which tin is found. The tungstic acid is also found mineralizing lime, form- ing tungstate of lime, and with lead, forming tungstate of lead. Tungsten, oxygen, constitute Oxide of Tungsten. Tungstic acid, iron, manganese, &c. Tungstate of Iron. Tungstic acid, lime, Tungstate of Lime. Tungstic acid, lead, Tungstate of Lead. Tungsten belongs to primitive countries. The only use to which tungsten has hitherto been applied, is in the arts, as forming, in combination with other sub- stancesj those red paints known by the name of lake. Of the Mettfls. 55 Chrome. Chrome is a metal of a greyish-white colour, extremely brittle, and is not six times heavier than water : it is worthy of note that, like the foregoing metal, it has not been fouud native, in the metallic form, but only in the state of an oxide : it is the only ore of chrome. Chrome, oxygen, constitute Oxide of Chrome. The chromic acid is found mineralizing lead, and forming the compound mineral called chromate of lead, which has been found principally in veins in gneiss and mica slate, in a gold mine in the Uralian mountains in Siberia; it is said also to have occurred at Annaberg in Austria, and at Trapettes in Savoy, and is commonly ranked among the ores of lead. The oxide of chrome, in combination with oxide of iron, alumine and silex, forms a mineral called chromate of iron, usually ranged with the ores of that metal, and which is found in France, in North America, and in some places in Siberia. Chrome has been detected by analysis as an in- gredient of some of the meteoric stones, or aerolites, and in the emerald, and two or three other earthy minerals, in the state of an oxide ; and in the Spinelle ruby, in the acid state. The chromate of lead, on account of its beautiful red colour, has been employed in Russia as a paint. Chrome, obtained in the metallic state by the chemist, from either of the two foregoing compounds, has not been applied to any important use : it tinges glass of a green colour. It has been ascertained that the emerald owes its beautiful green colour to oxide of chrome : it seems therefore probable that chrome may hereafter be employed as a paint. Osmium, Iridium, and Rhodium. These three brittle metals which, together with Palla- dium, already noticed as a malleable metal, have by analysis been found in combination with native Platina. Osmium and Iridium also oecur forming together a native alloy, in 56 Of the Metals. small grains, intermixed with, and of a somewhat paler colour than, the grains of platina. Not one of these metals has hitherto been applied to any use. Rhodium is about eleven times, Iridium eighteen times, heavier than water. Uranium. Uranium is a brittle, granular, hard metal, of extremely difficult fusibility, and of a reddish brown colour ; it is about six times heavier than water. This metal has never been found in any state having a metallic appearance ; consequently never in the pure state. Its ores are only two ; they are not common. They have been found in Saxony, Bohemia, Norway, France, and England. Uranium is found mineralized by the phosphoric acid^ forming the substance called Uranite ; or with oxygen^ when it is called uran-ochre. Uranium, oxygen iron, constitute Uran-ochre. Uranium, phosphoric acid, Uranite. The phosphate of uranium is a beautiful mineral, mostly in small thin plates of a fine green colour, and transparent : the combination of uranium with oxygen and oxide of iron, forms a mineral similar in appearance to pitch, or some- times resembling iron-rust. No use has hitherto been made of uranium. Cerium. Cerium has hitherto only been obtained in the metallic form$ in very minute quantity ; it is considered from its properties to be a metal. In the Cerite^ which has been found only in Sweden, Cerium, in the state of an oxide, is combined with iron, silex, lime, and water. In the Allanite, which was found in Greenland, and in another mineral from the Mysore, cerium is combined with oxygen, and small proportions of iron and silex ; it occurs also in some still more rare minerals in the state Of the Metals. 67 Cerium, oxygen, /row, siltx, constitute Cerite, Allanite. Cerium, oxygen, iron, manganese, yttria Orthite. Cerium, fluoric acid, Sub-fluate of Cerium, Deuto-flutte of Cerium. It has not been applied to any use. We have now completed a slight view of the nature of each of the metals. The arrangement in which we have treated of them, being grounded on their important pro- perties of malleability ) may therefore be said to be eco- nomical. We have also noticed the nature and composition of some of their ores. Before we dismiss the subject alto- gether, let us take a cursory geological view of them gene- rally. The metals and metalliferous ores are sometimes found in beds, but more often in veins, in hilly or mountainous countries. Sometimes they form almost the only substance of the beds or veins, but they are more often disseminated in them, through an earthy or stony substance, which thence is termed the gangue, or matrix of the metal or ore. But few metals or metallic ores occur disseminated in rocks ; and it is remarkable that the rocks in which they are so disseminated, are those which are generally esteemed to be of the oldest formation ; for when we come to treat of Geology, we shall find that experience has taught the observer to class rocks generally in three grand divisions ; namely, the oldest, which are termed primitive ; those of a middle age, termed secondary ; and the newest, termed alluvial. These divisions will hereafter be explained at large. Beds and veins, then, of metals and their ores are most common in primitive and the older secondary" rocks ; in the newer secondary they are less common ; and in alluvial deposits, they occur but very sparingly, never with regularity. In this point of view, then, which is strictly geological, the veins and beds of metalliferous ores are of different comparative ages. But this is not all. Certain of the metal? H 58 Of the Metals. are rarely found in primitive rocks, mostly in secondary ; others rarely occur in secondary, mostly in primitive ; others again are found chiefly in the newest primitive and older secondary. So that it appears vie have some geological data, on which to found a theory of the comparative ages of the metals. Iron and manganese have been detected by analysis in mica, a constituent of the oldest primitive rock, granite : tin and molybdena occur occasionally imbedded in it; these also, as well as tungsten, titanium, chrome ? cerium, uranium and bismuth, are found almost exclusively in such veins as traverse the oldest of the primitive rocks. All these metals may therefore be considered as of the ear- liest formation. Arsenic, cobalt, silver, nickel, and copper, are presumed to be less ancient ; because, though they occur in the oldest primitive rocks, they are also found in newer. Gold, tellurium, and antimony, are considered to be of a middle age, since they occur in the newer primitive and older secondary rocks. Lead, zinc, and mercury, are found in the greatest quantity in secondary formations, and are therefore supposed to be less ancient than the preceding. Platina, palladium, rhodium, iridium, and osmium, having never been found in situ, or in their native places, it is im- possible properly to judge of their relative ages; but as crude platina involves small portions of palladium, rhodium, iridium, and osmium, we may consider them to be of a middle age. There still remains one point of view in which we have not yet regarded the metals. Some are extremely rare, others very abundant. It may therefore be instructive to bestow a few minutes, On the relative proportions of the Metals. Iron is an ingredient of almost every rock, from the oldest primitive to the newest alluvial ; and also in very many earthy and metalliferous minerals, and in all soils : it is therefore considered to be the most abundant and most generally diffused of all the metals. Wherever found, and Of the Metals. 59 with whatever combined, it is mostly in the state of an oxide, except when combined with sulphur. Manganese is an ingredient of mica, which is a con- stituent of the oldest granite ; its ores occur both in primi- tive and secondary countries. Molybdena may be reckoned a rare metal ; it is occa- sionally found imbedded in granite, or in veins passing through it. It occurs only in the state of an acid or an oxide, or mineralized by sulphur. Tin is abundantly and almost exclusively found in veins passing through primitive rocks, chiefly in granite and argil- laceous schistus. Tin is always in the state of an oxide : it occurs only in one or two metalliferous ores. Tungsten is by no means a plentiful metal, it usually accompanies tin : it occurs only as an acid combined with iron, or with lime, in veins in primitive mountains. Titanium occurs chiefly in the state of an oxide, and may be reckoned a rare metal : it is usually combined with iron, sometimes with silex. Cerium is an extremely rare metal. Uranium is also rare : it occurs mineralized by the phos- phoric acid in primitive veins. Columbium or Tantaliitm is still more rare : it occurs in the state of an oxide ; in one of its ores it is combined with iron, in the other with the rare earth yttria. Chrome is a scarce metal, and occurs in the state of an acid, mineralizing lead and iron : also, though in very small quantities, as an oxide. Bismuth is not a common metal ; it occurs in the native state, also mineralized by sulphur, and combined in some of the ores of silver, and of cobalt. The preceding metals, being chiefly found in the oldest primitive rocks, are considered to be of the earliest forma- tion ; the succeeding five are supposed to be less ancient, because they occur both in the oldest primitive and in cer- tain of the secondary rocks. Arsenic is a more abundant metal than most of the pre- ceding : it is involved in small portions in several of the H 2 60 Of the Metals. native metals, in all the ores of cobalt, and in several of those of silver and of copper. Cobalt is not found alloying any metal ; in its ores it is combined with iron and arsenic ; it is not plentiful. Nickel is a rare metal : it occurs as an oxide, and also combined with arsenic. Stiver is a somewhat abundant metal ; and occurs in greater or less quantity in most mineral countries : in the native state, it occurs in veins and beds, and disseminated in rocks : its ores are numerous ; it occurs combined with lead, copper, iron, antimony, tellurium, gold, quicksilver, and arsenic, and mineralized by sulphur, and by certain acids. Copper is an abundant metal ; it occurs in the native state : its ores are numerous, and in them copper is com- bined with iron, sulphur, silex, oxygen, and certain acids : it occurs in most mineral countries. Most of the following metals are found in the newer pri- mitive and older secondary rocks, and therefore are metals of a middle age. Gold, though less abundant than silver, is more so than most of the preceding, and is not to be esteemed a rare metal ; though occasionally met with in veins, it is chiefly found in rivers and alluvial deposits : it occurs from 1 to 26 per cent, in the ores of tellurium, and sometimes in small portions alloying the native metals, copper, antimony, platina, and arsenic. Tellurium is a rare metal ; it occurs in the native state, but mostly is alloyed by a little gold : in its ores it is com- bined with gold, silver, lead, copper, and sulphur : it has only been found in two or three places. Platina is not a plentiful metal : it is chiefly found in certain districts in America, and only in the native state ; alloyed by small portions of gold, lead, copper, iron, palla- dium, osmium, iridium, and rhodium. Palladium is rare ; it is found with platina, in the native state, alloyed by small portions of platina and iridium. Of Combustibles. 61 Iridium and Osmium are found together forming an alloy, which accompanies platina ; they also alloy platina, and the former of them, palladium : they are both rare. Rhodium is found only alloying the platina of Peru. Antimony is not a very rare metal : it occurs in the native state, alloyed by small portions of iron and silver : in its ores it is combined with sulphur, silex, and oxygen : it occurs in few mineral districts. Lead may be considered as the most abundant and most universally diffused metal after iron : it never is found in the native state, but its ores are very numerous : it occurs abundantly mineralized by sulphur, and by certain acids ; and is found in the st&ie of an oxide : it occurs in certain ores of tellurium. Zinc is not a scarce mineral, but is pretty generally dif- fused : in its ores, it occurs combined with sulphur, iron, and oxygen. Mercury is found only in a few places, but is not scarce: it occurs native, and combined with silver, sulphur, and with certain acids. Cadmium has been found only in certain ores of zinc. OF COMBUSTIBLES. We now proceed to the consideration of those mineral bodies which from their peculiar properties are termed COMBUSTIBLES. These form, in the mineral kingdom, a class of substances by no means agreeing amongst them- selves in internal or external characters, and differing essentially from the earths, the alkalies, and the metals. Combustibles include both the hardest and the softest of mineral substances. Most of the metals whose properties are altered by com- bustion, acquire an increase of weight thereby; whereas combustible substances are sensibly diminished in weight by the same process ; which serves, as it were, chemically to unite their constituent elements. The product of some 62 Of Combustibles. of them is liquid, of others, solid ; if solid, they arc insoluble in water. The mineral bases of combustible substances may be said to be only two, viz. SULPHUR and CARBON. Combustible substances may be comprised in the follow- ing list : Sulphur Coal Diamond Jet Mineral Carbon Amber Plumbago^ or Graphite Hatchetine Mineral Oil Mellite, or Honey Stone Bitumen, or Mineral Pitch Retinasphalt Fossil CopaL Sulphur. Sulphur is a soft brittle substance, of various shades of yellow, and highly inflammable. It is found either nearly pure, when it is termed native sulphur, or in combination with several of the metals, whence their ores are termed sulphurets of those metals, and are very abundant ; but it has only been detected in one earthy mineral, the Fahlunite, of which it forms about 17 per cent. It exists in certain kinds of coal. Native Sulphur is of a pale greenish yellow colour, and is of about twice the weight of water. It occurs in beds of gypsum, and also, though but rarely, in the veins of primi- tive mountains. It is found in the mountains of South America, in the Apennines of Piedmont, in the Glaciers of Mont Blanc, in Spain, Hungary, Poland and Siberia ; sul- phur occurs in certain warm springs, in sufficient quantity to form a deposit when in contact with the air. Volcanic Sulphur is found in Italy, Iceland, and South America. The sulphur of commerce is chiefly obtained from the crater of the ancient volcano at Solfatara near Naples. Sulphur occurs both compact, and crystallized in the form of an acute octohedron, the common base of the two pyramids being rhombic. Sulphur is the base of the sulphuric acid, which consists Of Combustibles. 63 of 40 per cent, of sulphur and 60 of oxygen : and the sul- phuric acid enters largely into the composition of that abun- dant substance sulphate of lime or gypsum, and is likewise the mineralizer of some of the metals, as of lead, &c. Sulphur is believed not to be a pure elementary sub- stance : for, although its elements have not hitherto been ascertained, Kie assistance derived from Galvanism has enabled the chemist to detect hydrogen as one of its con- stituents, and tended to render it probable that oxygen is another of them. Carbon. The purest form in wl.ich Carbon is found is in the diamond ; for some experiments tend to prove that the actual quantity of carbon, in equal weights of diamond and of charcoal, is precisely the same. The diamond is pure carbon ; and the only difference between it and charcoal seems to be, that the latter contains either hydrogen or water, from which the diamond is absolutely free. Carbon is the basis of several of the combustible mine- rals, as of coal, bitumen, amber, &c. ; it is found in small proportion in a few earthy minerals, and is the base of the carbonic acid. Carbon, is in its purest Form in the Diamond, and it occurs with Coal as Mineral Carbon. Carbon and iron constitute Plumbago. Carbon, iron, &c. Anthracite. Carbon, hydrogen, Mineral Oil. Carbon, hydrogen, &c. Bitumen. Carbon, hydrogen, and earthy matters, &c constitute Black Coal Brown Coal Cannel Coal Dysodile. Jet Carbon, succinic acid, Amber. Carbon, &c. Hatchetine. The DIAMOND, which is the hardest substance in nature, was heretofore considered as an earthy or stony mineral ; but it has been proved beyond a doubt not to be an earthy substance ; for when heated to the temperature of melted 64 Of Combustibles. copper, and exposed to a current of air, it is found to b* gradually, but completely combustible. By this process it may be wholly converted into carbonic acid, and therefore consists of Pure Carbon. Diamonds are either colourless, or of a yellowish, bluish, yellowish green, clove brown, black brown, prussian blue, or rose red colour : they are found in detached crystals, the primary form of which is the regular octohedron. In Jndia, they are met with in an ochry gravel. The diamond mines extend through a long tract of country, from Bengal to Cape Comorin, at the foot of a chain of mountains fifty miles in length : the chief of them are now between Gol- conda and Masulipatam. Diamonds are also procured from the Isle of Borneo and from Brazil, where they are found in beds of ferruginous sand or gravel. The largest diamond hitherto discovered, is in the pos- session of the Rajah of Mattan, in the island of Borneo, where it was found about eighty years ago. It is shaped like an egg, with an indented hollow near the smaller end. It is said to be of the finest water. It weighs 367 carats. Now as 156 carats are equal to 1 oz. troy, this diamond weighs 2 oz. 169.87 gr. troy. Many years ago the governor of Batavia tried to purchase it : he sent to the Rajah a Mr. Stuvart, who offered 150,000 dollars, two large war brigs with their guns and ammunition, together with a certain number of great guns, and a quantity of pow der and shot. The Rajah, however, refused to deprive his family of so valuable an hereditary possession, to which the Malays attach the miraculous power of curing all kinds of diseases, by means of the water in which it is dipped, and with which they imagine that the fortune of the family is con- nected. The principal use of the diamond is in ornamental jewel- lery ; it is also employed by glaziers to cut glass, and by lapidaries to engrave the harder gems \ but for such pur- poses, those only are used which either cannot be cleaved in particular directions, or are so impure as not to be worth the expense. Of Combustibles. 55 MINERAL CARBON, or CHARCOAL, is greyish black. It occurs in plates or irregular pieces, in various sorts of com- mon coal. It has a glimmering, silky lustre, and a fibrous appearance, discovering a wood-like texture. It is some- what heavier than common charcoal, and is easily reduced to ashes before the blow-pipe, without either flame or smoke. PLUMBAGO, or GRAPHITE, is found in England, Scotland, France, Spain, Germany, and some other countries. Plum- bago is of a dark iron black, passing into steel grey ; it has a glistening metallic lustre, and is unctuous to the touch. The principal use of plumbago is in the making of what are called black-lead pencils ; for which purpose none has yet been discovered equal to that from Borrow di le in Cum- berland, where it occurs in a considerable mountain of argillaceous schistus traversed by veins of quartz ; but so little is generally known respecting the manner in which it occurs, that it seems uncertain whether the masses of plum- bago are deposited in veins, or disseminated through the mountain. Whence this mineral obtained the name of black-lead it is difficult to say, unless it was from the lead-coloured streak which it gives upon paper. It has been ascertained that lead does not enter into its composition, but that the purest plumbago consists of about 90 parts of carbon and 10 of iron. MINERAL OIL. Under this term are comprehended two substances, naphtha and petroleum ; both of which are liquid, highly inflammable, and lighter than water. Naphtha is nearly colourless and transparent ; it burns with a blue flame, much smoke, and a penetrating odour; and when pure, leaves no residuum. The most copious springs of naphtha are on the coast of the Caspian sea. It is employed externally for strains and bruises. The Persians and Russians are said to take it as a cordial. It is burned in the lamps of Genoa, for lighting the city. Petroleum, at the usual temperature, is rather thicker i 66 Oj Combustibles. than common tar, and has a strong, disagreeable odour. It it principally found in coal countries, as in Colebrookdale ; occasionally in Holland. It is also found in France, Italy, Switzerland, Germany., Hungary and Sweden. It is most plentifully found in Asia: round the town of Rainanghong in the Birman empire, there are 520 wells in full activity, into which petroleum Hows from over coal. No water ever penetrates into these wells. The quantity of petroleum annually produced by them amounts to more than 400,000 hogsheads. To the inhabitants its uses are important ; from Moussoul to Bagdad, it is used instead of oil for lamps ; when mixed with earths or ashes, it serves for fuel. When naphtha is exposed to the air and light, it becomes brown, thickens, and seems to pass into petroleum; and by the distillation of petroleum, an oil is obtained similar to naphtha. When petroleum is exposed to the air, it thickens, and passes into a kind of bitumen. Considerable alliance is thus proved to exist between Mineral oil, and the follow- ing substance, bitumen. BITUMEN, or MINERAL PITCH, is either elastic or com- pact. Elastic Bitumen is of various shades of brown. It has a highly bituminous odour, and is about the weight of water. It burns readily with a large flame and much smoke, but melts by a gentle heat, and is thereby converted into a substance resembling petroleum, or maltha, or asphalt, ac- cording to its previous consistence. Hitherto it has only been found in the Odin mine, near Castleton in Derbyshire, in secondary limestone. Compact Bitumen is of a brownish-black colour; one variety may be impressed by the nail, and is called maltha; another is very brittle, and is called asphalt. They consist of carbon, hydrogen, earth, and bitumi- nous oil. The softer variety has not been put to any use ; but the harder is used in varnishes, and is an essential part of those Of Combustibles. &J used by engravers. It is found on the shores of the Dead Sea, in the West Indies, and many other places. The ancients employed bitumen in the construction of their buildings ; and all historians are said to agree that the bricks of which the walls of Babylon were built, were cemented with hot bitumen, which gave them very great solidity. Bitumen was carried down by the waters v of a river which joined the Euphrates ; it was also found in the salt springs in the neighbourhood of Babylon. The Egyp- tians are also said to have employed it for the embalming of bodies ; constituting what we now call mummies. COAL. The bituminous substance called coal, though ranked among minerals because its basis is pure carbon, is now by many believed to be of vegetable origin ; because the substance which lies upon the coal, is always rilled with vegetable remains ; as well as because a wood-like appear- ance may be traced through every species of coal, even the most compact. On the subject of coal deposits, particularly our own, it is my intention hereafter to treat more at large. Goal may be divided into four species : brown coal, black coal, cannel coaly and glance coal. Brown coal is imperfectly bituminous ; in all its varieties it is fibrous, and in some of them its vegetable origin is so complete, as that the remains of the trunks and branches of trees are visible and almost perfect. Brown coal burns with a weak flame and disagreeable odour. It is found in alluvial strata, and in some others of comparatively recent origin : it is subdivided into four varieties, viz. Bitu- minized wood, Earthy Brown coal, Compact Brown coal, and Moor coal. In England it occurs at Bovey, near Exeter, and is called Bovey coal. It is also found in other countries. Black coaly which is the slate coal, and foliated coal of some mineralogists, is very bituminous, and is used for economical purposen ; it includes several varieties. It may, however, generally be said to be of a black colour, having i 2 68 Of Combustibles. an iridescent tarnish, and a high resinous lustre. It is com- posed of about 60 parts of carbon and 36 of maltha and asphalt, and 3 to 6 per cent, of earth and oxide of iron. It always occurs in nearly horizontal strata, which are abun- dant in Durham, Northumberland, Yorkshire, and in some other parts of England, and in several parts of Europe. Cannel coal is chiefly found at Wigan in Lancashire, but is more or less abundant in most collieries. It is very brittle, of a shining lustre, crackles and flies while burning, flames much and burns quickly, leaving only 3 or 4 parts in the 100 of ashes. The Splent coal found near Edin- burgh, is considered to be an inferior variety of Cannel coal. Glance coal is of a dark iron black, and has a bright metallic lustre. It burns \vithout smoke, and emits no sulphureous or bituminous odour. It generally consists of pure carbon, with some silex or alumine, and a small por- tion of oxide of iron. There are three varieties of Glance coal ; the conchoidal, the columnar, and the slaty ; the latter is again subdivided into three varieties, Anthracite, Kil- kenny coal, and Welch culm. Jet, or Pitch coa/, is generally of a velvet black ; it occurs in mass, and sometimes in the shape of branches, with a regular woody structure. It has a brilliant, resinous lustre. It is used as fuel, but the finer and harder pieces are worked into trinkets, under the name of jet. It is found in the Prussian amber mines in detached fragments, and is there called black amber ; also in several places in France, Saxony, Germany, and Spain. HATCHETINE occurs in veins in iron-stone at Merthyr Tydvil in South Wales, and is a soft whitish, or greenish substance, sometimes resembling spermaceti, sometimes bees wax. At a low heat it gives out an oil by distillation, leaving a coaly matter : it is unlike any other of the com- bustibles. AMBER is a mineral of a yellow, or reddish-brown, or of a greenish or yellowish white colour. It is found in nodules Of Combustibles. 69 or rounded masses, from the size of coarse sand to that of a man's head. Amber is found on the shores of the Baltic, of Sicily, and of the Adriatic sea, and occasionally in the gravel beds near London. Near the sea coast, in Prussia, there are regular mines of amber : under a stratum of sand and clay about 20 feet thick, succeeds a stratum of trees, 40 or 50 feet thick, half decomposed, impregnated with pyrites and bitumen, and of a blackish-brown colour. Parts of these trees are impregnated with amber, which sometimes is found in stalactites depending from them. Under the stra- tum of trees were found pyrites, sulphate of iron and coarse sand, in which were rounded masses of amber. The mine is worked to the depth of 100 feet, and from the circum- stances in which the amber is found, it may be inferred that it originates from vegetable juices. Amber sometimes incloses insects, believed to be of the ant species. The strong electric powers of amber are generally known. The origin of amber is not perfectly understood ; it is commonly considered to be a fossil resin somewhat mineralized. Amber yields by distillation an acid called the succinic acid, from the Latin succinum, amber; it leaves as the residue an extremely black, shining coal, which is employed as the basis of the finest black varnishes. When exposed to flame in the open air, amber takes fire and burns with a yellowish flame, giving out a dense, pungent, aromatic smoke, and leaving a light, shining, black coal. MELLITE or HONEYSTONE is a rare mineral, having hitherto only been found in Thuringia, in the district of Saal, and in Switzerland It occurs on bituminous \vood, and earthy coal, and is generally accompanied by sulphur. Mellite is softer than amber, is transparent, brittle, and electric, and is found crystallized in the form of an octo- hedron. When burnt in the open air, neither smoke nor flame are observable, and it eventually acquires the colour and con- 70 Of Combustibles. sistence of chalk. By analysis it gives a peculiar acid, called the mellitic cczW, in combination with alumine, to- gether with small portions of iron and silex. RETINASPHALT has been found at Bovey in Devonshire in opake lumps of a yellowish or of a brown colour, adhering to Brown Coal. It is brittle and soft, and consists of resin, asphalt and earth. FOSSIL COPAL, or HIGHGATE RESIN, was found in little masses of a dirty brown colour, and brittle. In the flame of a candle it takes fire, and before the blow-pipe burns entirely away. It was found in the blue clay of which Highgate hill consists. What has been said on this part of the subject, is cal- culated only to convey a slight outline of the elements of Mineralogy. There exists a vast multitude of mineral compounds which it has not been possible to notice, and which involve many inquiries and researches belonging properly to the mineralogist in his closet. It may be observed that although we should now have been ignorant of the existence of some of the earths and metals, but for the researches of the chemist, yet the pro- perties and uses of by far the greater number of those which are most useful to man, were known and employed in his service long before chemistry was pursued as a science. Perhaps not one half of the earths, metals, and combustibles, have in any important degree been hitherto turned to advantage. LECTURE III. Of Crystallization Of Mineralogy as essential to the Geologist. OF CRYSTALLIZATION. IN treating of the earthy, metalliferous and combustible substances, I have not often insisted upon the fact, that many, if not most of them are found in regular crystals : it would have been difficult to have introduced this curious and interesting part of mineralogy earlier, and in such a manner as it deserves, consistently with the nature and objects of the present work. This subject is susceptible of, and has received illus- tration by, the application of algebra and some branches of the mathematics to it : all I shall attempt will be purely mechanical, and will therefore convey to the beginner only an outline of Crystallization, referring him for further in- formation to the excellent < Familiar Introduction to Crys- tallography,' by H. J. Brooke, Esq. The term Crystal is derived from the Greek Kgvratfaos (Crustallos), signifying ice, which was so called on account of the ease with which it was liquefied. The term was afterwards applied to what is now called Rock crystal, by the Roman naturalists, as supposing it, both from its trans- parency and beautiful symmetrical forms, to be only water indurated by continued frosts in the mountainous regions of the Alps. Bnt finding that .certain salts* also took a * The term Salt has been so variously applied, that it is scarcely possible to give an accurate definition of it. It is now sometimes used to designate all the crystallizable acids, or alkalies, or earths; or com- binations of acids with alkalies, earths, or metallic oxides. Hence the division of compound salts, into earthy, alkaline, and metallic. 72 Of Crystallization. prismatic form, the term crystal assumed a more general meaning, and now includes all the regular, many-sided solids, whether of earthy or metalliferous substances, pre- sented either by nature or chemistry. There are comparatively very few substances that are not found naturally crystallized with more or less regularity. The forms assumed by some are very numerous and highly interesting. For instance, the carbonate of lime has been found in about 300, and the oxide of tin in about 180 varieties of form : and as of both these, as well as most other substances, the crystals may be broken in particular directions, the true definition of a crystal seems to be this, that it has not only a regular external figure, but also a regular internal structure. This structure in the crystals of several minerals, is readily exemplified by mechanical means, by the knife, the hammer, or the pincers, pro- ducing fractures, or cleavages of perfect regularity. We will now proceed to mechanical illustrations of these assertions ; and the pupil is recommended to convince him- self of some at least of the facts about to be noticed, by procuring the crystals of the substances hereafter men- tioned, and operating upon them by the knife or the ham- mer ; or to apply the knife to models formed of chalk or of soap. Let us take a crystal of Fluor spar in one of the simplest of its natural forms, the cube (fig. 1). If then we apply the knife to one of the corners or solid angles, we shall find that, by pressure, it may be removed, leaving a bril- liant triangular surface ; and if we proceed in the same manner with the other seven corners, we shall produce in like manner, seven other triangular planes, and the crystal Of Crystallization. 73 will then have fourteen planes and resemble fig. 2 ; and by increasing these little triangular planes, we shall produce fig. 3 ; by still increasing these planes, we shall produce a figure resembling fig. 4, in which the form of the triangular plane is altered, and the planes of the original cube are greatly diminished : by still pursuing the fracture, we shall produce fig. 5, in which no part of the original cube ap- pears, but in lieu of it, an octahedron^ which is termed the regular octohedron, because all its sides are equal, as well as its planes ; and hence this solid is termed the primary form of fluor. But if we take a cube of common salty or a small mass of it in a cubic form, we shall find it to be impossible to take off the corners of the cube, as in the case of fluor; and further, we shall find that this substance can be cleaved, so as to produce regular planes, or bright surfaces, only parallel with the planes of the cube^ which therefore is termed the primary crystal of common salt. Again, if we break a crystal or mass of calcareous spar, we shall find that we can cleave it only into the form of a rhomboid, which "is its primary form. Or if we attempt to cleave the sulphate of barytes, it will be found to break with regularity only parallel to all the planes of a right rhombic prism, the primary form of the substance. Now it will require scarcely a moment's reflection to be convinced that if, as respects all the above mentioned sub- stances, their crystals can be cleaved only in particular directions^ and that by breaking them in these directions alone we can obtain clear and brilliant surfaces, that such effects must be the consequences of the regularity with which the little particles or molecules of which they must be composed, are disposed in regard to each other. This, in minerals, is termed structure. What may be the forms of these particles or molecules has not yet been, nor probably ever will be determined with certainty. It is however probable that they differ in respect of form in different minerals, since their primary 74 % O/ Crystallization . forms differ. Nor can we have any conception of the size of these molecules, since it is impossible to conceive a par- ticle so minute that it cannot be still diminished. Of this however we are certain, that how small soever they may be, the molecules composing the forementioned substances cannot be simple, but must be compound : take fluor spar, as an instance ; the minutest particles into which we can reduce it, must each consist of several elements primarily of lime and fluoric acid ; but then we must recollect that lime is not itself a simple substance, but a compound of calcium and oxygen, while fluoric acid is a compound of fluorine and oxygen. These inquiries are extremely interesting, but here we must leave them. Whether, then, these molecules may be in all cases of the same form, or whether they differ in different primary forms, or whether polarity alone may be the cause of their arrangement, we do not pretend to decide. It is however a remarkable fact that the cause of this arrangement, what- soever it may be, produces similar effects, in the same substance, wheresoever it may be found \ for fluor spar, whether it be found in England, in Siberia, or in America, affects the same external forms, and can be cleaved into one regular form, namely, the regular octohedron ; the same remark applies to all other minerals ; cleavage therefore is one of the safest guides in the recognition of minerals, even though it does not exist in all minerals, as for instance in gold and native copper ; and even where it does exist, the lamina? are not in all cases removed with equal ease. The topaz can only be readily cleaved in one direction : the crystals of some minerals, although they may be cleaved in several directions, can only be readily fractured in one or two : and the crystals of several substances, although they sometimes present indications of their real structure, have never yet been regularly fractured. This diversity in the structure of crystallized bodies has not been satisfactorily explained ; we only know the fact. Many minerals, however, are found in a great number of forms. Fluor appears in at least 100 varieties of external Of Crystallization. 75 form, and calcareous spar in above 300; and some even minute crystals exhibit upwards of 100 little planes or facets. These at first puzzle the inquirer not a little ; but patience and perseverance are not long in unravelling the mystery, and in tracing the same plane (that for instance which is created by displacing the corner of the cube, and which often appears in natural crystals) through all the different degrees of replacement to which it is liable. And moreover, the discovery is soon made as to its connection with the several planes with which it may happen to be combined ; that is to say, whether they may arise from the replacement of the angles or edges of the primary form, or whether they belong to planes lying obliquely in regard to one or the other of them ; and thus we become enabled to trace these complicated forms through their many inter- mediate varieties, into that one simple form which is termed the primary crystal, and from which all the others are derived by means of replacements on the edges, angles, &c. All the known primary forms, are comprehended in the five following solids, namely, The Octohedron, Tetrahedron, Hexahedral prism, Rhomboidal dodecahedron, Parallelopiped. Of the Octohedron there are several varieties; three of ihe most obvious are selected. 1 2 3 The regular octohedron (fig. 1.) is so called, because it is a solid contained under eight planes, each of w Inch is a triangle equal and similar to each of the others ; and which, having all its three sides of the same length, is therefore K 2 76 Of Crystallization. termed an equilateral triangle. A line drawn from its summit to its lowest extremity or angle, is precisely of the same length as a line from any other of its angles to its opposed angle. As the primary crystal of some substances, is found an octohedron, much flatter than the regular, and therefore called an obtuse octohedron (fig. 2) : two of the three lines, bounding each of its eight triangles, are shorter than the third. A line drawn from the summit to its lower extremity or angle, is shorter than a line from any of its other angles to its opposed angle. An octohedron is found to be the primitive crystal of some substances, which is much longer than the regular octohedron, and is called acute (fig. 3), because its upper and lower angles are more sharp or acute than the other four angles. Two of the three lines bounding each of its eight triangles, are longer than the third ; and a line drawn from the upper to the lower extremity or angle, is much longer than one drawn from either of its other angles, to the opposed angle. Of the octohedron there are some other varieties, of which it is not now requisite to enter into an explanation. The Tetrahedron is a solid comprehended within four planes, each of which is a triangle equal and similar to the rest, having each of its three sides of the same length. It is the simplest of all the primary forms. The Hexahedral prism is a solid compre- hended within eight planes, which are not all similar. Its upper and lower planes, called the terminal planes, are alike, being six-sided or hexagonal : each of the six sides being of the same length. The other six planes, which are called the lateral planes, are alike in regard to each other, and in the figure annexed are not perfectly square. The fact is, that the hexahedral prism, as the form of the primary crystal of various sub- stances, differs in respect of height: such determinations however rank among the extreme niceties of the science. Of Crystallization. 77 The Rhomboidal dodecahedron is a solid com- prehended within twelve planes, all of which are perfectly alike in form ; each plane being a rhomb, of which the four bounding lines are all equal in length, and are parallel two and two, forming two acute and two obtuse angles on each plane. The term Parallelepiped includes every solid contained under six parallelograms ; that is, under six planes whose bounding lines, two and two, are parallel with each other, and whose opposite sides are equal and parallel. Among these solids, are the cube, the square prism, the rhomboid, the right rhombic prism, and the oblique rhombic prism. The Cube (fig. 1) is a body of perfect proportion; all its sides are equal all its planes are square. The piimary forms of some substances are much flatter than the cube ; of others, they are much higher : these are then termed square prisms (fig. 2). The Rhomboid (fig. 3) differs from the cube essentially ; none of its planes are square, but they resemble each other; two of the opposed angles of each plane are more obtuse, the other two are more acute than those of the planes of the cube. Of rhomboids there are several varieties ; that is, the angles of their planes are more or less acute and obtuse : these rhomboids therefore differ in a greater or less degree from the proportions of the cube. The right rhombic prism (fig. 4) differs from the square prism (fig. 2) in this particular. The sides of the square prism meet each with the next at a right angle, that is, neither more nor less than 90 degrees, and the summit, or terminal plane, with the sides, at the same angle. But in the right rhombic prism the sides meet alternately at angles more and less than 90 degrees, and hence two opposite angles are acute, while the two other opposite angles, formed 78 Of Crystallization. by the meeting of the side planes, are obtuse. The terminal meet the side planes, however, at a right angle, or 90. There are several minerals besides the sulphate of barytes already mentioned, which have a right rhombic prism as the primary form, but, and it is somewhat remarkable, the measurements of the acute, and consequently of the obtuse angles at which the side planes meet, commonly differ from each other in different minerals : there is no one among them of the same measurements as those of the sulphate of barytes. The oblique rhombic prism (fig. 5) differs from the right rhombic prism chiefly in respect of the position of the ter- minal planes, which is not at right angles to the side planes, but oblique to them : and hence the terminal and lateral planes meet alternately at angles more and less than 90. Such are the prevailing forms of the primary crystals of mineral substances : there are however many niceties re- specting them too minute for attention in so general and slight a view as we are now taking of this interesting de- partment of mineralogy : some geologists of the present day are induced almost to smile at the investigations of the crystallographer, as being unnecessarily minute and tedious ; it is however certain, that although the Geologist may gain a tolerable knowledge of the newer rocks in absolute igno- rance of crystalline form, he w ould find himself completely foiled in his researches among the component minerals of the older rocks, without a competent knowledge of it. But even a slight view demands a few further observations. We have already spoken of the lateral and of the terminal planes of crystals ; when any two of them meet, they form an edge, and hence we have lateral edges and terminal edges ; when any three or more meet, we have a solid angle; the meeting of three planes of the cube contribute to form its solid angle, while that of the octohedron is caused by the meeting of four planes. The connection of one form with another, or the transition of one into anotherj is observable in the instance of the Of Crystallization. 79 cube and octohedron at page 72, clearly shewing that the octohedron may be made to result by the production of planes in place of the angles of the cube, by replacing its solid angles. When in nature, the edge or angle of a crystal does not appear, but instead of it a plane, the crystal is said to be modified; the edge or angle is said to be replaced^ or truncated. Let us attend to the process by which a rhomboidal dodecahedron (fig. 3) may result from the replacement of the edges of the octohedron (fig. 1). 1 2 3 In fig. 1. the edges of the octohedron are replaced by long narrow planes : in fig. 2, these planes are increased, and the triangular planes of the octohedron are much di- minished, and in fig. 3 they are lost, the figure being a complete rhomboidal dodecahedron : the series is not unfrequently observable in fluor spar, and especially in the red oxide of copper : but the rhomboidal dodecahedron cannot in either mineral be produced from the octohedron by cleavage, because the laminae of the crystal can only be removed in directions parallel to the planes of the octo- hedron, which is the primary form in both cases. The above is cited as one of the most simple and interesting transitions of one form into another. A few words will shew the connection of crystallography with calculation. The circle is by common consent divided into 360 degrees. Now it has already been observed that any two planes of the cube meet together at a right angle, or 90 degrees, being a quarter of the circle, if then we were to measure the cube all round in one direction, we should have four angles to take, since (in reference to its position on a table) it has four lateral planes, consequent!/ 80 Of Crystallization. four edges ; and four times 90 are equal to 360 degrees, that is, equal to the whole division of the circle. Let us next attend to the right rhombic prism on this point. It has been said that its lateral planes meet alter- nately at more and less than 90 degrees, two opposite lateral angles being obtuse; the other two, acute; the obtuse are more than 90, the acute are less : now since this form, as the primary of different substances has different measurements, we may assume what we please. Let us then suppose the two obtuse angles meet at 100 degrees each, being together equal to 200 degrees out of 360 : if that were the case, we should find, on measuring the acute angles, that the amount of the two added together would equal the difference between 200 and 360, or 160, that is, each would be 80: and it is always found to be the fact, that the united measurements of a crystal of four sides, equal 360. Hence it becomes apparent that a crystal is a geometrical solid) of mathematical nicety in regard to form, and subject to calculation, not only as regards the primary planes , but also, it must be obvious in relation to its modifying planes ; as for instance those little triangular planes which replace the solid angles of the cube in page 72 ; and if we were to measure the angle formed by the meeting of this little tri- angular plane with either of the three planes with which it is in immediate connection, we should find the angle to be precisely the same in each instance. These facts open to the imagination a wide field for observation : and we can no longer feel surprise that the mathematician should have pursued this subject to a great extent : that he should have measured and calculated the relations of almost every plane to those of the primary crystal of each substance, and thereby have made it appa- rent that every crystalline form has a beautiful connection with science, proving the perfection of the geometry of nature as exhibited in the numerous and apparently com- plicated little planes of even very minute crystals. With the intention of measuring these angles, an instru- Of Crystallization. 81 ment has been invented, called the goniometer, meaning the measurer of angles ; but we may conclude that its use scarcely admits of perfect accuracy ; and for this reason the few most conversant in its use, have differed in the results obtained from the same substances. Another instrument has since been invented by Dr. Wollaston, called the rejlective goniometer., because its use depends on the reflections to be observed upon the natural polish on the planes of crystals. This instrument has al- ready done service to science in detecting some fallacies, arising from a reliance on the former instrument. When once the angles of the primary crystal of any sub- stance are accurately ascertained, the angle at which any two of its planes meet, is calculated with wonderful pre- cision by the assistance of geometry. The angles formed by the meeting of any two planes of each of the five regular solids, the cube, the regular octo- hedron, the tetrahedron, the hexahedral prism, and the rhomboidaj dodecahedron, already enumerated among pri- mary crystals, are known, because they all are regular geometrical solids. But it has already been said, that there exist as primary crystals, varieties of the parallelepiped and of the octohedron^ which differ from each other both in shape and measurement. As instances ; the primary crystal of quartz is a rhomboid very different to that of carbonate of lime, and much more nearly approaches the cube. The primary crystals of the oxide of tin and of zircon, are octohedrons, differing from each other, but are much more flat than the regular octohedron ; while the octohedron which is the primary crystal of sulphur, is much longer and more acute. The primary crystal of kyanite is a four-sided and oblique prism, with rhombic terminations, while that of the sulphate of barytes is a four- sided rhomboidal prism also with rhombic terminations. The difficulty therefore is, to obtain the precise admeasure- ments of those primary crystals, which are not regular geometrical solids. It is probable that the reflective go- niometer of Dr. Wollaston will discover, that the principal L $2 Of Minera logy, as essential to the Geologist. part of the calculations hitherto made in regard to the angles of such primary crystals, and of the numerous facets to be observed on them, (which, not belonging to the primary crystals, are therefore termed secondary planes), are incorrect; and for this reason; this goniometer will assist in measuring the angles of crystals as small as the head of the smallest pin, if their planes be perfectly bril- liant ; and it is ascertained that minute crystals are always more perfectly formed than large ones. Now the calcu- lations already alluded to, are grounded upon measurements taken by the common goniometer upon large crystals, the planes of which rarely are perfectly formed and smooth : even such as have brilliant planes, and seem therefore adapted to the use of the reflective goniometer, seldom afford similar results : measurements taken upon cleavages are most to be relied on. OF MINERALOGY, AS ESSENTIAL TO THE GEOLOGIST. A very limited knowledge of Mineralogy will suffice for the Geologist who proposes to confine his views to rocks of the newer formations, in accordance with the prevailing taste of the present day ; but for one ambitious of a wider field, of an acquaintance with the older and compound rocks, a certain extent of mineralogicai knowledge is essen- tial to him. Before he can begin his career, as a Geologist, he must become enabled to detect the several ingredients of a compound rock, in their often minutely divided por- tions. To accomplish this, he will not need to study minerals universally, but it is essential for him to become intimately acquainted with a few substances, in their simple and separate state ; for nothing can be more obvious than the fact, that if he would recognise a small particle of a mineral when aggregated with particles of other minerals in a mass, he must first have become acquainted with at least its most important characters. In determining the ingredients of a compound rock, the labours of the chemist Of Mineralogy , as essential to the Geologist. 83 cannot avail, because its parts are generally too minute for his operations ; hence we must rely on characters, if pos- sible, equally certain and more readily attainable, than those which would be derived from chemical analysis. We must look to the external characters^ such as hardness, &c. and particularly to ttructure, which comprehends the forms into which a mineral can be cleaved with regularity, and which is the most decisive of all. The few minerals which enter into the composition of rocks as common and essential ingredients, may be said to be comprehended in the following list ; to which are added lists of occasional minerals, and of the most common of those occurring in veins. Components of Rocks. Quartz Indurated Clay Hornblende Felspar Hornstone Augite Cleavelandite Mica Hypersthene Compact Felspar Chlorite Diallage Clinkstone Talc Limestone. Clay stone Steatite Minerals sometimes interspersed in Rocks, or occasionally forming masses in them. Calcareous spar Jasper Iron pyrites Dolomite Tourmaline Oxidulated iron Spathose iron Pitchstone Arsenical iron Flint Obsidian Sulphuret of Chert Garnet molybdena. Chalcedony Oxide of tin Minerals of frequent occurrence, in veins chiefly. Fluor spar Native copper Phosphate of lime Yellow copper ore Selenite Red oxide of copper Carbonate of barytes Sulphuret of copper Sulphate of barytes Sulphuret of lead Common iron stone Carbonate of lead Clay iron stone Sulphuret of zinc Oxide of man gun es e Carbonate of sin c. 84 Of Mineralogy ^ as essential to the Geologist. An acquaintance with the minerals just named, which in number are not quite equal to fifty, will be found at once to form a good foundation for the study either of mineralogy more generally, or of geology. In respect of geology, which now forms the immediate point of interest, an empirical acquaintance with their external characters as simple minerals, is first to be attained. And as the most ready mode of acquiring this, I would recommend that a specimen of each should be obtained, both compact and crystallized, where they so occur in nature, duly cata- logued, and with a little ticket, containing the number of reference to the catalogue, attached to each ; and that, after the specimens shall have been compared duly with each other, and their characters separately studied by means of a reference to some work on mineralogy, the student should keep the minerals in one drawer, and the catalogue in another, to prevent a too easy reference to it : and by this mode of proceeding, he will soon learn to recognise each, and at once to pronounce its name on. taking it into his hand. In this attempt at recognition by means of the exter- nal characters, he will find their relative weight in the hand, and relative hardness when the plane of one is scratched by the angle of another, excellent auxiliaries. But in order to gain such a knowledge of these substances as will avail him in geology, he must go still further, he must examine the structure of such as are found in the crystalline state, or in regularly crystallized forms ; and he ought to know the general forms of the crystals of such minerals as occur in veins. Regularity of form is often interrupted in the com- pound mass, because the crystal of one mineral often robs that immediately contiguous to it of that symmetry which at once would serve to distinguish it to the practised eye of the mineralogist: hence it not unfrequently happens that the only resort of the mineralogist is, the structure of the mineral in question ; and to obtain bright and measur- able planes, it is sometimes requisite only to raise the mineral from the mass by introducing an iron point below it, when it often separates into pieces or lam in 33 in the Of Miner alo gy, as essential to the Geologist. 85 direction of its natural joints, producing regular cleavages: and these how small soever, if brilliant, serve readily for the detection of the mineral by the assistance of the reflec- tive goniometer^ and a reference to the list of primary forms in the excellent Treatise on Crystallography by H. J. Brooke, Esq. In proof of the necessity of this mode of proceeding, it may be mentioned that in granite, and many other rocks, it is essential to distinguish Felspar from Cleavelandite, which often cannot be done by the eye alone, but they are immediately separated by the goniometer : the same remark applies to hornblende and atigite ; to calcareous spar, dolo- mite, and spathose iron. LECTURE IV. Of the objects of Geological enquiry Hypotheses Geologi- cal positions- Of the low and level parts of the Earth Of the Chalk basins of Par 'is , of London, and of the Isle of Wight. IT was said on a former evening that the object of mineralogy is the study of mineral bodies in particular, -whether simple or compound : that geology embraces the study of the globe in general, and of the various relations that the different masses of which it is constituted, bear to each other. Mineralogy may be therefore said to furnish, as it were, the alphabet to geology. The globe we inhabit is about 8000 miles in diameter, 25,000 in circnmference. Its surface has two grand di- visions, land and water : one third or thereabouts, being occupied by land, and two thirds by water. So little was known by the ancients respecting the earth, (of its real form and unceasing revolutions they were abso- lutely ignorant), that it was by them considered to be the centre of the universe ; of which, a more correct philosophy has proved it to be only a subsidiary portion. It is net therefore surprising that in the pursuit of our present ob- ject, we derive little or no benefit from the writings of ancient authors. In the time of Herodotus the Greek his- torian, it may however be inferred that there existed some philosophers who imagined the earth to be round, and encompassed by the sea, since the historian takes the opportunity of ridiculing the opinion. Until towards the end of the last century, geology was little understood ', perhaps because those sciences on which Geological Hypotheses. 87 it greatly depends, chemistry and mineralogy, had not made any large advances towards their present state. It is no marvel therefore that in default of a knowledge of these sciences, and of that research by which alone we can be- come acquainted with the constituent masses of the globe, the activity of the human mind should attempt to account for the creation and present state of the earth by unin- structed efforts of the imagination. It may be amusing to give a short account of a few of the hypotheses that have been proposed. In these hypotheses, two events only, the creation and the delu.ge, seem to have entered into the calculations of the inventors, as comprehending all the changes to which the globe has been subjected : that is to say, each arbitrarily ascribed to it a certain primitive state, which each sup- posed to have been altered and modified by the deluge. In the opinion of Burnet, the whole earth at first con- sisted of an uniform light crust, which covered the abyss of the sea ; and which, being broken for the production of the deluge, formed the mountains by its fragments. According to Woodward^ the deluge was occasioned by a momentary suspension of cohesion among the particles of mineral bodies ; the whole mass of the globe was dissolved, and the soft paste became penetrated by shells. fVhiston fancied that the earth was created from the at- mosphere of one comet, and deluged by the tail of another. The great Leibnitz amused himself, as did also Descartes, by conceiving the world to be an extinguished sun or vitri- fied globe : upon which the vapours, condensing in propor- tion as it cooled, formed seas, which afterwards deposited calcareous strata. Demailtet conceived the globe to have been covered with water for many thousand years ; that it gradually retired ; that all the terrestrial animals were originally inhabitants of the sea ; that man himself began his career as a fish. Euffon imagined that the mass of our earth, together with the other planets, were struck off the sun in a liquified state, by a comet, at the same time. 88 Geological Hypotheses. Some modern philosophers have supposed that an uni- versal fluid originally existed, which gave birth to animals of the simplest kind ; that in process of time the races of these animals being complicated, and dying, supplied cal- careous earth or lime ; that aluminous earth or clay was supplied by the decay of vegetables. That these two earths were re-dissolved, and finally converted into silex ; hence that the more ancient mountains, are siliceous. Thus the solid parts of our globe, according to these visionaries, owe their existence to animal or vegetable life ; and without it, would have continued entirely liquid. Kepler^ one of the greatest of astronomers, considered the globe to be possessed of living faculties and a circu- lating vital fluid ; that all the particles of it are alive and possess instinct and volition, whence their attraction and repulsion : that the organs through which the huge animal breathes are the mountains ; that mineral veins are ab- scesses, and metals the products of rottenness and disease. These systems, and even many more than these, have had their admirers, and have successively sunk into disrepute and neglect in proportion to the advance of chemical and physical science. It is the apology, if indeed it be not rather the shame, of their inventors, that they knew little of mineralogy, nothing of the structure of the earth. Two or three theories of a date much later than the foregoing of the end of the last and beginning of the present cen- tury, are worth notice. Marschall supposes the fragments of which the surface of the earth is composed, to have fallen from heaven. Bertrand has supposed that the earth is hollow, and contains within it a load-stone, which is dragged from one pole to the other by the attraction of comets ; so as, by changing its centre of gravity, to drown alternately the two hemispheres. Jameson, now a professor of natural history in one of our own universities, has lately published this amusing query ; c As the true figure of the earth is still unascertained, may we not conjecture, from what is already known, that it i? a polyedron (a figure of Geological Hypotheses. 89 many sides), and that the strata, under determinate angles, form the sides and cleavage of this great crystal' ! ! If philosophers, and even naturalists, will still condes- cend to amuse the world with conceits like the foregoing, it is no wonder that the present period, with respect to the theory of the earth, should have been said to bear some resemblance to that, in which certain philosophers thought that the hea-vens were formed of polished stone, and that the moon was no larger than Peleponnesus. Almost equally absurd, they merit equal notice as examples of extravagant theory ; but they convey to us at the same time this in- structive lesson, that it is only by the patient investigation of facts and of natural phenomena^ that we can hope to approach the truth, in the sublime study of the history of the earth. Within the last few years mineralogy, and other inves- tigations connected with it, have made advances so rapid, that geology is thereby greatly raised in rank among the sciences. A review of modern researches and discoveries will strikingly evince the folly of any attempt to account, by a turn of the pen, for the creation of the globe, or for the revolutions to which it has been subjected. Researches amongst the phenomena of the earth will assure us, that in whatever manner the mighty display of Omnipotence in its creation was effected, it has since suffered great changes on its surface. It is probable that chemistry will yet make great altera- tions in the catalogue of elementary substances, either by addition or diminution ; ultimately, it is most probable, by the latter. We shall however assume those which have already been enumerated, (page 4,) according to the pre- sent state of our knowledge, to be the constituents of which the various masses of the crust of our globe are compounded; but, whether the globe is to its very centre a mass of these compounds, we know not : and since there seems no pro- bability of our arriving at any certainty on this head, let us forbear to conjecture. It in the business of the geologist to investigate the natural facts and phenomena within our 90 Geology in its infancy. < reach ; and let us be assured that when these fail to accom- plish any desirable purpose, we shall add nothing to our knowledge by soaring into the regions of fancy. On a former evening it was said that as the miner rarely descends below jaoopth part of the earth's diameter, so, if we sup- pose the earth in shape to resemble an orange, it may be said that we know nothing but of the outer rind. Geology, therefore, in the present true sense of the term, embraces little more than an inquiry into the history and present state of the surface or crust of the globe. Disclaim- ing theory, it is my purpose to adhere to the legitimate objects of science, as they have been just described, with- out exerting one pretension beyond them. Much has been written on the subject of the creation ; a subject so far beyond our limit, that upon it I shall be silent; nor shall I attempt to follow others through a laborious undertaking to reconcile our partial knowledge of the phenomena of nature, and of the constituent masses of the globe, with the Mosaic account of the creation. If ever it should be permitted that man shall comprehend the great plan by which the Creator reduced to order the materials of which the globe is composed, with the same certainty as he has attained a knowledge of the mechanism of the universe, more certain data and discoveries M'ill be allowed to him, than as yet have fallen to his lot. Geology is yet in its infancy : shall we not therefore do wisely in concluding that we are not in the possession of materials sufficient for the investigation ? We have no reason to dis- believe that this important branch of geological inquiry will hereafter be better understood ; but considering the present state of our knowledge, we shall be best and most reasonably employed in the investigation of the present state of the earth, and of the changes to which its surface has been subjected ; taking as our text the incontrovertible truth, that * In the beginning God created the heaven and the earth/ Some of the most acute geologists of the present day, hav not yet agreed whether the agent employed in the Objects of Geological inquiry. 91 magnificent work of reducing to order the elementary sub- stances of which the earth is composed, was fire or water* There exist at this moment among geologists, two distinct parties, distinguished according to the notion they embrace, by the appellations of Volcanists and Neptunists. Each loudly asserts the preference of its own theory ; each being in the possession of chemical facts, or of natural phe- nomena, which establish in its separate opinion its own claim to preference, that have not been controverted by the other. Distinct however, from these, there are many who wisely think that we are yet too ignorant to be able with pro- priety to establish any theory at all. These are collecting evidence in regard to its actual state from every quarter of the globe, which if faithfully recorded, may hereafter en- able mankind more nearly to approach the truth than at present it is possible. To the results of these inquiries, in so far as they have proceeded, it is my present object to invite your attention. They will comprehend much on the consequences of the catastrophes that have befallen the surface of the earth by the agency of water, of which we have abundant and in- controvertible evidence; inquiries into the nature and component masses of mountains, and of their relative heights ; the internal structure of the earth ; the nature f mineral veins ; the deposites of salt and of coal ; and of volcanos. These are inquiries well meriting our attention; they will exhibit to us the investigations of men, who, being philosophers in the true sense of the word, have sought and still continue to seek among the instructive records of revolving ages, amid the ruin occasioned by time and cir- cumstance, the history of the globe we inhabit ; of the materials composing it, the causes and progress of their decay and destruction, as well as of their renovation or reconsolidation. He who resides in a country which exhibits an almost perpetual verdure, uninterrupted by barren rocks, or deso- late regions, and has never visited any other, will scarcely M2 92 i)f low level Countries. suspect that the surface of the globe has been much con- vulsed bj successive revolutions and various catastrophes. If however he descend to any considerable distance beneath its surface, or ascend the hills that border the plain, he will be likely to receive a new train of ideas ; his mind will become expanded in proportion to the expansion of his view. But if he ascend the chains of elevated mountains, or follow the beds of descending torrents which lay open their interior structure, he will become prepared to believe to the full extent, that the catastrophes which have befallen the globe since its creation have been many and various. IVe reside in such a country ; a country of perpetual verdure, uninterrupted by a single rock, or one desolate place. The elevations that surround us scarcely merit the name of hills ; and being all alike verdant, they admit not of investigation, beyond what is attained by the sinking of wells. Few of us have visited other countries ; not many have seen the more mountainous parts of our own ; scarcely one present, perhaps, knows the internal history of the spot which now supports him. We generally know that it principally consists of clay, to a considerable depth ; but the greater part have yet to learn that this clay has unques- tionably been deposited by the sea, that it encloses sea- shells and various petrifactions which are of marine origin, and that the whole country surrounding us to a great depth and extent, is of this nature. It seems to me that we cannot do better than to begin our inquiries into the nature of such countries as that in which we live of low and level countries; from which we may rise to the consideration of such as are somewhat more elevated, and thence to the nature and component masses of mountaino is regions. But level countries are so little open to the investigation of the geologist, and seem to afford, when compared with the more obvious masses of mountains, so little to attract his attention and research, that the nature of the larger tracts of such country is but little understood. Mineral bd and veins ar for the most part situated in hills, or Of lois and level Countries. 93 eminences of more considerable elevation ; to these there- fore the attention of the miner and the mineralogist, as well as of the geologist, has hitherto been principally directed : the component masses of mountains are known the best. During the short period that mineralogy and geology hare ranked among the sciences, they have made rapid advances : within the present century considerable attention has been given to the exploring of some tracts of level country, which have amply paid the research. From the actual nature of these, we may reason by analogy of the rest. In Europe, the principal tracts of low or level country are, the eastern parts of England, the Netherlands, and the northern parts of France and Germany, and the whole of Poland. In Asia, the north-east parts of Russia, called the Steppes. In America, there are vast tracts of low land, through which the Mississippi and the Missouri rivers take their course. The extent of the low lands of Africa is not ascertained. The surface of the lowest and most level countries, it must be observed, does not, generally speaking, consist of such rocks as constitute the regular strata of the crust of the earth ; but for the most part of a covering of the debris or ruin of those rocks. This ruin is consequently the most recent deposit ; and is found not only forming the plains of flat countries, but also filling up hollows in mountainous regions. We may, by reflection and observation, readily convince ourselves, that the action of the air and of moisture even on the hardest rocks, necessarily leads more or less to their constant though slow decay ; and the ruin thus formed by causes in ceaseless operation, is carried down by the streams : deposits thus formed are termed AlluviaL But it is manifest that causes of far greater importance and violence have acted upon the surface of the earth ; beds of sand and gravel and loam, in almost every level tract, overspread the regular strata, and these frequently contain fragments of rocks which belong to different and distant tracts of country ; in proof of this it may be cited, that 94 Of low and level in the gravel beds in our own neighbourhood I have found fragments of basalt, a rock which is not known to exist so near London as 100 miles. These fragments must there- fore have been transported and deposited among the gravel, by some agent that was equal to tearing up and carrying away the parent rock ; and when we reflect that the gravel has not sharp edges and angles, but that on the contrary, though it has manifestly been broken, its edges and angles have generally been rounded by the rubbing of the portions against each other, we may fairly infer that this could only have been the consequence of the violent and long-continued action of currents of water, of a deluge, or of successive inundations, to which the surface was long since subjected: deposits of this nature are termed Diluvial. It is chiefly in diluvial deposits that the bones of nu- merous land animals are found, and many of which are extinct. From what is certainly known it may be asserted, that the lowest and most level parts of the regular strata constituting the crust of the earth, when penetrated to a considerable depth, exhibit nearly horizontal beds, composed of various substances, and containing, almost all of them, innumerable marine productions. Similar strata, with the same pro- ductions, compose the hills even to a considerable height. Shells are sometimes so numerous in them as to constitute the entire body of the stratum ; they are often in so perfect a state of preservation as that their sharpest ridges are re- tained : they are found in elevations far above the level of the ocean, and in places to which the sea could not be con- veyed by any existing cause : they are sometimes enclosed in loose sand, sometimes filled or penetrated by the hardest stone. Every part of the earth, every continent, and almost every island, exhibits the same phenomena. It was once, long ago it is true, asserted that these remains of shells, and other organized bodies, were merely the sports of nature ; but it has been frequently found that the nicest and most scrupulous comparison of their forms, cannot detect the slightest difference between some of and of elevated Tracts. 95 these shells, and the shells which still inhabit the sea. They have therefore once lived in the sea, and been de- posited by it ; the sea must consequently have rested in the places where the deposition has taken place. Hence it is evident that the basin or reservoir containing the sea, has undergone some change at least j either in extent, in situation, or in both. The traces of revolutions become still more apparent and decisive if we ascend a little higher, and approach nearer to Ihe foot of great chains of mountains ; still many bedi of shells are found, some even larger and more solid, and the shells are quite as numerous and well preserved, but are not of the same species as those found in less elevated regions. Here the strata are of various degrees of inclina- tion, and sometimes instead of being horizontal, as in plains and low hills, are even vertical. The strata of great chains of mountains, of whatever composed, or however placed, are laid open to view by means of vallies which time and violence have produced. The diversity existing in the inclination of strata, clearly point out, in the estimation of many geologists, that by gome means these have been broken and overturned. The operation of an agent equal to the breaking up and overturning of the strata of mountains, and, if I may so say, to the destruction of rocks, and to the forming anew whole tracts of country w hich enclose the remains of or- ganized bodies, was, it cannot be doubted, equal to the disruption of vast portions of continents, thereby forming islands : and it must in all probability have almost univer- sally changed in appearance and even in form, the surface of the globe, It is beyond a doubt that there have been many catas- trophes of the same nature, though not perhaps of equal extent. What has been the agent employed in the produc- tion of these catastrophes, is most obvious. It is not to be doubted that there have been successive irruptions and re- treats of the sea ; and it seems equally certain that the final result has been the universal depression of its level. 96 The Sea has bee?* higher than it not? is. As we ascend to still higher points of elevation, and ad- vance towards the summits of mountains, the remains of marine animals, and that multitude of shells already spoken of, begin to grow rare, and at length disappear altogether. We arrive at strata of a very different nature, which con- tain no vestige of living creatures ; nevertheless, certain circumstances cbservab'e in all these strata, in which not a trace of organic remains is to be found, have induced gome geologists to suppose that their bare and rugged sum- mits, though elevated far above the strata containing shells, have also been moved or overturned ; others consider them to be in the very place and position in which they were originally deposited. But though, by some, rocks of the greatest elevation are not considered to be precisely in the place and position in which they were originally deposited, they are nevertheless generally considered to be of older formation than all other rocks ; because they contain no animal remains, and be- cause the rocks which enclose such remains, rest upon, but are never found under, such as do not contain them. They have therefore been called Primitive Rocks. Rocks of this description rise through others at various elevations in every quarter of the globe ; but in their great- est elevation, primitive mountains traverse our continents in various directions, rising above the clouds; separating the basins of rivers from each other, and serving, by means of their perpetual snows, as reservoirs for feeding springs ; and forming, in some measure, .the skeleton, or, as it were, the rough frame-w ork of the earth, I shall here recapitulate what has just now been said ; and shall afterwards proceed to its elucidation, by ad- ducing such proofs, drawn from the observations of men who have made the phenomena of the globe their study, aa may be consistent with the nature of the subject and our present object. Geological Positions. 97 1. That the lowest and most level parts of the earth consist of horizontal strata, composed of various sub- stances, many of them containing marine productions. 2. That similar, but variously inclined, strata are found in hills to a great height. 3. That shells are sometimes so numerous as to con- stitute entire strata. 4. That shells are found far above the level of the sea, and at heights to which the sea could not be raised by any existing cause. 5. That these shells once lived in the sea, and were deposited by it. 6. That shells continue to be found as we rise to the foot of great chains of mountains. 7. That at this elevation, the strata, instead of being horizontal as in the plains, are of various degrees of in- clination, and sometimes vertical. 8. That from these and other circumstances it is in- ferred that there have been frequent irruptions and retreats of the sea. 9. That as we approach the summits of lofty moun- tains, their strata become wholly different, the remains of marine animals and shells become rare, and even dis- appear altogether. 10. That even these elevated strata are, by some, considered not to be precisely in the position in which they were formed. 11. That, as they contain no vestige of animal re- mains, they are generally considered to be the oldest rocki, and therefore are called primitive. The consideration of these points will naturally involve inquiries into others which may be termed subsidiary to them. In order however to present a more complete out- line of Geology, it will be necessary to add to these a number of other inquiries, more within the province of the mineralogist. Of these I shall now add a general view ; and after attempting an elucidation of the foregoing, shall in like 98 Geological Positions. manner proceed with these, and present to your notice the experience and observations respecting them, of men who have studiously investigated the phenomena of the globe. 12. That rocks, which, because they include no ves- tige of animal remains, are termed primitive, are of various kinds. 13. That rocks enclosing animal remains, are never found underneath, or supporting, those rocks which are termed primitive. 14. That some primitive rocks alternate with each other, but that granite is found beneath all others, and frequently overtops all the rest. 15. That rocks which include organic remains, must have been formed after the shells they contain; and therefor e, not being considered primitive , they are by some termed secondary rocks: whence the terms used by geologists of primary and secondary formations. 16. That there are many varieties of secondary rocks, each of which has received a geological appellation. 17. That there exists another class of substances not appropriately termed rocks ; but which, being considered to be the debris or ruin of rocks, by their long exposure to the action of air and water, or both, are therefore termed alluvial deposits. I now proceed to the illustration of the first position, viz. That the lowest and most level parts of the earth con- sist of horizontal strata, composed of various substances, many of them containing marine productions. The illustrations necessary to this position will include many of the newest, most striking, and most important geological facts. These facts will prove, to a limited extent, another of our assertions, namely, that the catastrophes to which the surface of the globe has been subject have been numerous : and it will be shewn that some of these have not been owing to irruptions of the sea, but to the agency of fresh water ; and it will clearly appear that depositions by fresh and by salt water have been alternate. Order in the deposition of Rocks. 99 In order to make the whole of these circumstances more intelligible, it will be requisite a little to anticipate, by adverting, here, to some geological facts, which, according to our previous arrangement, would belong to another place. Geologists who have had ample opportunity of examining mineral deposits in large and mountainous tracts of coun- try, have satisfactorily ascertained that certain of them are always found beneath, never above, certain other de- posits. Investigation has proved that rocks which do not contain animal remains are always found beneath, never resting upon those rocks, which do contain animal remains : and also that those deposits which are termed alluvial, as gravel, sand, &c. are never found beneath other rocks, but always resting upon them. Thus much it seems necessary to premise of geological fact, previously to entering on a detail of the extraordinary circumstances which I shall adduce to prove the truth of our first position. An investigation of the country surrounding Paris to a considerable extent, which by comparison may be termed low and level, has lately been accomplished by the eminent naturalist, Cuvier, associated with the acute geologist, Brongniart, and they have published a masterly delineation of the geological situation of the country. Now as chalk makes its appearance on the edge of tljis district, and almost surrounds Paris, though at a consider- able distance from it ; and as the surrounding chalk is found to dip beneath the soil within the district, and has in many places and at various depths been discovered far beneath its surface, by the sinking of wells and pits ; it is justly concluded that the soil on which Paris stands, and the surrounding country, to a great extent, was actually deposited in a large hollow consisting of chalk, which therefore has been termed by Cuvier and Brongniart, the chalk basin of Paris. Immediately covering the chalk is found a small stratum of plastic clay, used in the manufacture of different kinds of pottery. On the plastic clay rests a deposit by salt N 2 100 Chalk basin water, thence termed a marine formation :* above this rests a deposit by fresh water y thence termed a fresh water formation : next above is found a second marine formation : above it, a second fresh water formation ; and upon this rests an alluvial deposit. I now proceed to a more par- ticular description of the nature of these five deposits. 1st deposit. On the plastic clay, covering the bottom of the chalk basin, it has been said that the lower marine formation rests. This formation consists of coarse lime- stone abounding in marine petrifactions : associated with it, is a series of strata in regular order, as marl, sand- stone, &c. all of which enclose marine shells, many of them still retaining their pearly lustre. Occasionally the space usually occupied by the limestone and the series of other strata, is entirely filled with siliceous limestone without shells, resting on the plastic clay and supporting the deposit about to be described. 2d deposit. Upon the lower marine formation rests .a deposit by fresh water. It consists of gypsum covered by a bed of white friable marie, enclosing petrified wood of the palm kind, and the remains of fishes and shells : the gypsum contains remains of extinct quadrupeds, birds, amphibious animals, fishes and shells, all of which are of land or fresh water species. This deposit is therefore called the lower fresh water formation. In the Gypsum, Cuvier discovered the bones of five varieties of an extinct animal, which he calls the paleEOtherium, (signifying ancient large animal,) varying in size from a sheep to a horse ; and the bones of five varieties of another extinct animal, which he calls the anoplotherium (signifying beast without weapons; it had no canine teeth), varying in size from the horse to the ass. Both these species he considers to have been natives of the country over which Paris is now built. * The term formation is not always used to express a deposit con- sisting only of a single stratum or bed; it is also commonly used to designate a number or series of beds or strata, which being intimately associated, and containing the same description of organic remains, are thence, as well as from a variety of other circumstances obvious to the experienced geologist, considered to be of contcmporaneout formation. of Paris. 101 He also found the bones of an unknown species of the dog, and of the fox ; also of an ichneumon double the size of the living species. Nearly an entire skeleton of a quadruped of the genus didelphis was also found, but not belonging to any of the existing species, which are natives of America. The fossil bones of birds are not so readily known as those of other animals; but Cuvier describes some, found along with the bones of the extinct animals, as belonging to the pelican, the starling, and the quail tribes. Among amphibious animals, the bones of the tortoise and the crocodile are recognized. Of fossil fish, there are five varieties, most of them are allied to the present species of fresh water fish. The shells all belong to fresh water fish. 3d deposit. Above the beds of gypsum and marie, just described as containing the remains of fresh water ani- mals, lie two beds of oyster-shells, separated by a bed of sand and sandstone, without shells, from a bed of sand and sandstone, containing marine shells. These seem to have formed but one deposit by salt water. The two beds of oyster-shells are separated by a thin bed of white marie. The shells of the lower bed are numerous, thin, small, and brown. The upper bed of oyster-shells is very thick, and the shells are arranged as they are found in the oean : the greater number of them are whole, and have both valves. On the bed of sand and sandstone above described, rests a bed of clayey sand and marie, in which lies the buhrstone or millstone. As it contains neither vege- table nor animal remains, it seems not sufficiently characterized to be referred decidedly either to the preceding, which is a marine formation, or to the suc- ceeding deposit, which is afresh water formation. 4th deposit. Above the buhrstone or millstone, lies a deposit of limestone and of siliceous substances, as flint, pitchstone, and jasper. The siliceous matter is some- times allied in character to the millstone. But the essential character of the whole of the deposit is, that it contains fresh-water and land-shells, nearly all of which 102 Chalk basin belong to the genera now living in morasses. This for- mation extends 30 leagues to the south of Paris. 5th deposit. Above the four deposits just described, as being alternately from fresh and salt water, lies the alluvial deposit, which appears to be by fresh \vater, and is composed of variously coloured sand, marie, and clay. It contains rolled stones of various kinds, but is most remarkable for its enclosing the remains of large organic bodies : in it are found great trunks of trees, bones of elephants, of oxen, rein-deer, and other large land animals. This account of the contents of the Paris chalk basin contains important geological information. The space to which this investigation is limited, is indeed small, when compared with the surface of a globe of 25,000 miles in circumference, one-third of which is of land. But if the investigation of so small a comparative spot, should not be deemed conclusive in regard to the probable nature of low and level countries in general, we have only to refer to the natural history of other parts of France and of other coun- tries ; of Germany, and of many tracts in the north of Europe, to be convinced, than at least in degree, the same effects have been almost universal. But a more recent geological investigation of certain districts in our country,* gave results, in most points, per- fectly coinciding with the observations of Cuvier, in regard to the chalk basin of Paris. The minutiae of this inves- tigation were detailed in a very interesting communication to the Geological Society, since published in the 2d volume of its Transactions. At present we cannot do more than notice its results, It appears that in this country there are two chalk basins, in considerable degree resembling that of Paris. One of them is called the Isle of Wight basin; the other, the London basin. * By T. Webster, M.G S. of the Isle of Wight. 103 The Isle of Wight basin comprehends the district be- tween Newport in that island on the south, Southampton on the north, Brighton on the east, and Dorchester on the west. The strata which cover the chalk in this district, are individually and collectively of various thicknesses ; occasionally only tw o or three of them are found, and some- times only one of them ; but there is one place on the southern edge of this basin, which proves beyond a doubt that the same causes which operated in the Paris basinj extended their influence to the Isle of Wight, and probably at the same period of time. The place to which I allude is Headen Hill, forming a part of Alum Bay, near the western angle of the Isle of: Wight. Of this hill, which is about 300 feet high, a natural section has been laid open, since its deposition, doubtless by the sea which now borders it. Any one may therefore easily satisfy himself that it contains the same description of strata as have been found in the Paris basin, and pre- cisely in the same order ; that is to say, alternate salt and fresh water deposits, enclosing shells, perfectly similar to those found in the Paris basin. Of the truth of this we have evidence. It is ascertained by a comparison of the shells taken from the corresponding deposits in both basins : and the animal remains so compared, are now deposited in the collection of the Geological Society in London. The London basin begins at Deal in Kent, and extends (not in a right line) by Canterbury to Gravesend ; compre- hending the whole of Kent north of that line, except the Isle of Thanet, which is of chalk. The edge of the basin from Gravesend crosses the Thames at Grays, extends to Purfleet, whence it crosses the Thames again, and passes nearly in a strait line to Guildford, and from Guildford to a little west of Hungerford in Berkshire, whence it turns nearly north-east, to Maidenhead, Eaton, Watford, Hert- ford, Stansted, and Thaxted> and extends to the northern Coast of the county of Norfolk. In a word however, the chalk basin in which London is situated, is comprehended 104 Chalk basin in an acute triangle, one of its longest sides extending from Hungerford to the northern Coast of Norfolk, the other from Hungerford to Deal ; its shorter side taking in the whole coast from near Cromer in Norfolk to Deal, with the exception of the Isle of Thanet. A perfect coincidence of the London with the Paris and Isle of Wight basins, in regard to the alternate depositions by salt and fresh w r ater, does not exist, because these de- posits do not alternate in the London basin. The stiff blue clay which prevails to so great a depth almost every where round and beneath London, is unquestionably a marine deposit, all its numerous animal remains being those of sea animals. This clay lies immediately under the fine bed of gravel on which London is built. Some wells in London pass through this clay from 200 to 300 feet; at Tottenham about 130; at Lord Spencer's at Wimbledon, 530 feet ; at Harrow on the Hill, 70 feet ; at Primrose Hill, near Hampstead, 500 feet without success ; and, except in the latter instance, all arrived at the same bed of white sand, from which the water rose. By a paper not long since read before the Royal Society we find that at Brentford they lately passed 200 feet through the stiff blue London clay, without arriving either at water or chalk : above the clay lies a stratum of sand, gravel, and water ; over that another, of 1 to 9 feet of loam ; then 7 feet of sandy gravel ; and then above, 9 feet of loam. These strata, lying over the clay, contain a vast collection of the bones of elephants, both African and Indian, of the hippopotamus, the horns and jaws of oxen, the horns of deer, and both land and fresh water shells. These consti- tute that species of deposit which is termed Diluvium; whereas the clay on which it rests, contains only the remains of sea animals. The diluvium therefore commonly rests, in the London basin, upon the great bed of clay, but there exist slight traces in some places, of a deposit by fresh water, between the clay and the diluvium. The clay of the London basin corresponds with the lower marine formation of the Paris basin, but the traces of a of London. 105 freshwater formation occasionally existing between the clay and the diluvium, are not sufficient to decide its agreement with the lower freshwater formation of the Paris basin. The analogy of the two basins terminates with the clay ; because the alternating deposites by salt and fresh water in the Paris basin, are wanting in that of London. In the strata above, as well as in those below the chalk, in the north-eastern parts of England, there is a remarkable agreement in point of position, in several places ; in some, one or more of the strata may be wanting, but the order in which they lie seems never to be inverted. If however we would take a wider range for proofs of the more, general existence of the catastrophes that have befallen the surface of the globe, we shall easily find con- viction. We are speaking now only of those to which the lower and most level parts of the earth have been subjected. On the banks of the Firth of Forth in Scotland there is a remarkable bed of sea shells, which begins about two miles westward of Borrowstonness ; whence it extends in a line parallel with the banks of the Forth upwards of three miles ; preserving in all the parts of its course, nearly the same elevation of 33 feet above the level of the river. Be- tween the high bank in which this bed occurs, and the shore of the Forth, there is an extensive deposition of dilu- vial soil, nearly a mile in breadth, and in a high state of cultivation. The shells in this bed, which varies in thick- ness, but in one place where it is distinctly seen, is upwards pf three feet, are all inhabitants of the sea, and are still found in it. Amongst them the oyster occurs in great abundance, the common muscle but sparingly. The, shells are intermingled in sand. The valves of the bivalve shells are generally detached and broken into moderately sized fragments ; so that the bed presents an appearance of con- fusion. The shells are altered in their texture, being soft and friable. It seems probable from these circumstances that this bed of shells was deposited during a violent agi- tation of the sea. The Botanic garden at Edinburgh is on a sea and ; in 106 Remains of Animals which fragments of sea sheila have occasionally been found. It is 40 feet above the level of the sea. Von Buch found beds of sea shells in Norway at various degrees of elevation. At Tromsoe he found them 20 feet, at Haudolm 30 feet, at Luroe about 40 feet. The bones of a species of rhinoceros, different from either of the three species of Africa, Asia, and the Isle of Sumatra, have been dug out of the alluvial soil near Canterbury ; and since, in many places of Germany, France and Italy. In Siberia, not only single bones and skulls, but the whole animal with flesh and skin has been discovered. In the alluvial soil of France and Italy, have been found the bones of an hippopotamus, allied to the two only species now known, inhabitants of Africa and Sumatra; as well as the bones of another animal not allied to these, and entirely different from any of the existing species of qua- drupeds. The tapir is an animal peculiar to South America, yet two fossil species have been found in Europe : the one small, the other gigantic : both have occurred in different parts of France, Germany and Italy. Of the elephant, the only existing species are those of Africa and Asia. One fossil species has been discovered, differing from each, but most nearly allied to the Asiatic. It is the mammoth of the Russians. The bones of the mammoth have been found in the diluvial soil near London, Northampton, Gloucester, Harwich, Norwich, on Salisbury plain, and in other places in England ; they also occur in the north of Ireland ; and in Sweden, Iceland, Russia, Poland, Germany, France, Holland, and Hungary, the bones and teeth have been met with in abundance. The teeth have also been found in North and South America, and abundantly in Asiatic Russia. Pallas says, that from the Don to the Tchutskoiness, there is scarcely a river that does not afford the remains of the mammoth, and that they are frequently imbedded in alluvial soil, containing marine productions ; the skeletons are seldom complete, still more in the newest deposits. 107 seldom is the fleshy part of the animal preserved : but an interesting instance of this has been described.* * The following account of the singular discovery of the carcase of a mammoth is given by Professor Cuvier, as taken from a report in the supplement to the Journal du Nord, No. 80, by M. Adams, Adjunct member of the Academy of St. Petersburg. * In the year 1799, a Tungusian fisherman observed a strange shape- less mass projecting from an ice-bank, near the mouth of a river in the north of Siberia, the nature of which he did not understand, and which was so high in the bank as to be beyond his reach. He next year observed the same object, which was then rather more disengaged from among the ice, but was still unable to conceive what it was. Towards the end of the following summer, 1801, he could distinctly see that it \vas the frozen carcase of an enormous animal, the entire flank of which and one of its tusks had become disengaged from the ice. In consequence of the ice beginning to melt earlier and to a greater degree than usual in 1803, the fifth year of this discovery, the enormous carcase became entirely disengaged, and fell down from the ice-crag on a sand-bank forming part of the coast of the Arctic Ocean. In the month of March of that year, the Tungusian earned away the two tusks, which he sold for the value of fifty rubles ; and at this time a drawing was made of the animal, of which I possess a copy. ' Two years afterwards, or in 1806, Mr. Adams went to examine this animal, which still remained on the sand-bank where it had fallen from the ice, but its body was then greatly mutilated. The Jukuts of the neighbourhood had taken away considerable quantity of its flesh to feed their dogs; and the wild animals, particularly the white bears, had also feasted on the carcase; yet the skeleton remained quite entire, except that one of the fore-legs was gone. The entire spine, the pelvis, one shoulder-blade, and three legs, were still held together by their liga- ments and by some remains of the skin ; and the other shoulder-blade was found at a short distance. The head remained, covered by the dried skin : and the pupil of the eye was still distinguishable. The brain also remained within the skull, but a good deal shrunk and dried up ; and one of the ears was in excellent preservation, still retaining a tuft of strong bristly hair. The upper-lip was a good deal eaten away, and the under-lip was entirely gone, so that the teeth were distinctly seen. The animal was a male, and had a long mane on its neck, ' The skin was extremely thick and heavy, .and as much of it remained as required the exertion often men to carry away, which they did with considerable difficulty. More than thirty pounds weight of the hair and bristles of this animal were gathered from the wet sand-bank, having been trampled into the mud by the white bears, while devouring the Some of the hair was presented to our Museum of Natural o 2 108 Remains of Animals Five species of an animal more nearly allied to the elephant than to any other living species, have also been discovered : it has been called the mastodon. The five species are all herbivorous, the largest is about the size of the elephant ; but no living species of the mastodon has been discovered in any part of the world : the fossil remains were found in Europe and America. All these fossil species of quadrupeds have occurred in alluvial or diluvial soil that covers the bottoms of vallies, or is spread over the surface of plains ; none have been found in high valiies : the bones of some were covered by marine shells and remains, others by fresh water shells ; and as no remains of these animals have been seen in any solid rock, or in any high mountain, it seems probable that these ani- mals fell victims to some of the latest catastrophes that have befallen the globe ; and though some of them differ from their co-species now existing in the torrid zone, there seems reason for supposing them to have been inhabitants of the regions in which their bones are found. The mammoth found whole in Siberia was too warmly clad for the torrid zone. Additional proofs of the extensiveness of these catas- trophes, both by salt and fresh water, may be found in the famous rock of Gibraltar, and at various places on the coast of the Mediterranean. The rock of Gibraltar is principally limestone, and is traversed by fissures or hollowed into caves, which contain a peculiar compound mass, consisting of angular fragments of limestone, of bones, usually of ruminating animals, ge- History by M. Targe, censor in the Lyceum of Charlemagne. It con- sists of three distinct kinds. One of these is stiff black bristles, a foot or more in length j another is thinner bristles, or coarse flexible hair, of a reddish-brown colour; and the third is a coarse reddish-brown wool, which grew among the roots of the hair. These afford an un- deniable proof that this animal had belonged to a race of elephants inhabiting a cold region, with which we are now unacquainted, and by no means fitted to dwell in the torrid zone. It is also evident that this normous animal must have been frozen up by the ice at the moment of its death.' in the newest deposits. 109 nerally broken, never in skeletons ; and of land shells, cemented together by a calcareous basis : the bones were for a long time thought to be those of monkies, but Cuvier has with his peculiar sagacity, considered some of them to belong to a species of antelope, others to a kind of mouse. At Cette, the limestone includes bones like those of a rabbit ; others similar to those of the field mouse, and of a bird of the sparrow tribe : the vertebrae of a serpent, to- gether with the bones of some ruminating animal, and three various kinds of land shells. At Nice and the Antibes, the rock also contained the bones of the horse. In Corsica, the rock contains the bones of small quadru- peds, chiefly foreign to the place ; as those of one inhabiting the coldest and wildest parts of Siberia ; and enormous quantities of bones, some of which resemble those of the field mouse, and others those of the water rat. In Dalmatia^ the bones contained in the rock arc prin- cipally like those of Gibraltar. At Concud in Arragon, the rock contains the bones of the ox, ass, a small kind of sheep, and many land and fresh water shells. We have now, as it seems to me, satisfactorily illustrated our first position to a considerable extent, viz. ' That the lowest and most level parts of the earth, consist of hori- zontal strata, composed of various substances, many of which contain marine productions.' LECTURE V. Organic remains visible in hills and on the sides of elevated mountains Strata oftheBrocken mountain Summits of lofty mountains contain no organic remains Division of rocks into several classes. ON the last evening, the real objects of Geological inquiry were pointed out. It was shewn that these consist of the natural phenomena and facts every where discoverable ; and that without an ample and nice investigation of these, it is impossible for us ever to attain a reasonable knowledge of the earth : such a knowledge, I would say, as may be derived from some acquaintance with the component masses of its crust, and of their relative positions. It was also shewn how unsatisfactory and absurd are the speculations of mere closet-philosophers ; who, relying on their inven- tive powers, and on the extreme difficulty of contradicting their theories, indulged themselves in speculations scarcely less ridiculous than it would be to assert that the globe is an egg or an oyster. During the last evening also, were laid down a series of geological positions^ as they may be termed, which have been found to result from the truly philosophical labours of men who have investigated the crust of the globe, perhaps to as great a height and to as great a depth, above and beneath the surface of the sea, as man can easily attain. These geological positions I proposed to illustrate by quoting the experience of the very men from whose labours they have resulted. The first of them, viz. c That the lowest and most level parts of the earth, when penetrated Research the only sure Geological Guide. 1 1 1 to a great depth, exhibit nothing but horizontal strata, composed of various substances, and containing almost all of them innumerable marine productions,' was then eluci- dated by the investigation of the chalk basins of Paris, of London, and of the Isle of Wight : and not only the truth of the foregoing position was made clearly to appear, but also the novel and interesting facts, that in two of these basins there have been successive and alternate deposits from salt and fresh water ; as has been proved by the nature of their strata, and the organic remains they respectively contain. And it was further shewn that these catastrophes so fatal to animal life, have not been partial ; inasmuch as they are readily and largely seen in almost every part of the European continent, and particularly on the coasts of the Mediterranean sea. Our present inquiry into the nature of the constituent masses of the crust of the globe, since we cannot peisonally investigate them, does not admit of those immediate con- victions of the truth of our assertions, as might be desirable. I claim however this advantage ; I demand no assent to theory, for I will not broach a theory. I offer alone the results of inquiries among the facts and phenomena of nature, by men whose love of nature and of truth, has ren- dered their researches invaluable to science : researches amid regions always open to the investigations of the doubting or disbelieving. Amongst these men, let us re- member that we have an Humboldt, a Werner, a Saussure, and a Cuvier. What but the love of truth and of science could have induced Humboldt to traverse whole continents, or to ascend the Andes more than 19,000 feet above the level of the sea; or Werner, the great German geologist, to employ his time in examining the rude and mountainous regions which surrounded him, and in teaching the results of his inquiries ? What but the love of truth and of science could have led Saussure to investigate every corner of the Alps, during twenty years ; or have induced Cuvier to bestow twenty-five years of his life in the study of com- 112 Organic Remains parative anatomy and osteology, with a view principally, if not solely, to the illustration of the nature of our globe ? If from all that Humboldt, and Werner, and Saussure, and Cuvier, and many other intelligent geologists, have observed in regard to the nature and respective positions of the great masses forming the crust of the earth, we were to select such parts as would immediately come in evidence of the truth of the geological positions already submitted to your notice, scarcely fifty evenings would afford time sufficient for their recital. It is my wish to bring the required evidence into the narrow est compass ; I shall therefore select only such as may suffice to attain our object ; taking care, at the same time, that it shall be of the most obvious kind that the nature of our inquiry will permit. The positions already recited begin with the lowest and most level parts of the earth ; these we have considered. We now ascend a little, that is to say, to the hills ; and after a short notice of their nature, shall rise to the con- sideration of the masses constituting lofty mountains ; taking occasion, here, to present an outline of the divisions which the experience of geologists has taught them to make in rocks, as the component masses of the crust of the globe ; .shewing the reasons for their division into primitive, tran- sition and floetz (or secondary), and alluvial ; and that of each of these there are many varieties. The 2d position is, That strata containing shells are found in hills to a great height. 3d. That the shells are sometimes so numerous as to constitute entire strata. 4th. That shells are found far above the level of the sea, and at heights to which the sea could not be raised by any existing cause. 5th. That these shells once lived in the sea and were deposited by it. 6th. That shells continue to be found as we rise to the foot of great chains of mountains. in lit I Is. 113 These positions I purpose to consider together. The evidence of facts requisite for their support, and as proofs of their truth, need not detain us long. The cliffs of the Isle of Sheppey, bordering our own river the Thames, do not rise to any considerable height above the level of the water. They have however long been celebrated for the numerous organic remains found in them, a list of which was published several years ago. This list has since been enriched by a gentleman now resident at Faversliam, by the addition of above 700 different species of fossil fruits, berries, and ligneous seed vessels. Among the animal remains found in these cliffs, are several varieties of the crab, the jaws of crocodiles, and lobsters nearly whole. It deserves notice that all these remains, both vegetable and animal are entirely impregnated with sul- phuret of iron, or pyrites. At Reading in Berkshire, or rather in the elevated lands in its neighbourhood, are found considerable deposits of oyster shells ; it is remarkable that many of them are entire, having both their valves united, but the animal matter, or oyster, is entirely decayed. These shells have not under- gone the process of petrifaction ; they are white, extremely brittle, and readily separate into lamina?. In Touraine in France, 100 miles from the sea, and about 9 feet under the surface, there is a bed of shells 9 leagues long and about 20 feet thick. According to Ulloa, there are similar deposits in Peru. Such are likewise well known to exist in almost tvery part of Europe. In the neighbourhood of Bath, at a rather higher elevation, large tracts of limestone are found, consisting almost wholly of shells ; which are also discover- able in great abundance in the Gloucestershire hills, and in other parts of England. In the cliffs near Whitby, a crocodile has been found ; in those near Lyme in Dorset- shire, their remains occur in considerable abundance ; and in the chalk cliffs of Dover, some varieties of fossil shells. Still higher, in various parts of Germany, the fossil remains of fish are found in hills and rocks of various kinds of slate. Let us however continue to ascend. Dolomicu found 114 Shells in Mountains immense quantities of sea shells on the sides of Mount J5tna, 2000 feet above the level of the sea; and at the height of 2400 feet above the same level, he found in the mountain itself, regular strata of grey clay enclosing sea shells. Some of the lower hills of the Appennine chain contain many species of shells ; they contain also the fossil bones of elephants, of the rhinoceros, of the hippopotamus, of whales and of dolphins. It is asserted by Cuvier, in regard to the shells which are found imbedded in some rocks, that ' A nice and scrupulous comparison of their forms, of their contexture, and even of their composition, cannot detect the slightest difference between some of these shells, and the shells which still inhabit the sea ;' an assertion which perhaps no one who has at all examined it, will presume to deny. Surely then we have a right to assume that they once lived in the sea, and that they were deposited by it ; and if deposited by it, that the sea must have been once suf- ficiently elevated ; since we know of no other cause adequate to the deposition of rocks enclosing sea shells in well de- fined and regular strata. And when we take into consider- ation that on the sides of Mont Perdu, which is the highest of the Pyrenees, and reaches an elevation of 11,000 feet above the level of the sea, so immense a quantity of sea shells are to be seen, as that some of its strata seem almost wholly composed of them ; we shall at once assent to the position that shells are found in places to which the sea could not be conveyed by any existing cause. Mont Perdu is by no means the only elevated mountain enclosing sea shells ; it is however one of the highest ; and we may readily infer that if a mountain of so great elevation encloses them, they will be found in the strata at the foot of great chains of mountains. According to Saussure, the Buet, a mountain which rises 10,000 feet above the level of the sea, contains no petrifac- tions ; but the Salenche, the Mole, and others not exceeding their strata are highly inclined. 115 7000 feet, are found to enclose petrifactions, although they form a part of the same chain. The Altaic chain of primitive mountains in Siberia en- closes no animal remains ; but it is flanked on each side by a chain of hills which encloses marine shells. The 7th position is, That at the foot of lofty moun- tains, the strata, instead of being horizontal as in plains, and low hills, are of various degrees of inclination, and sometimes vertical. 8th. That from these and other circumstances, it is inferred that there have been successive irruptions and retreats of the sea. 9th. That as we approach the summits of lofty moun- tains , their strata become wholly different ; the remains of marine animals and shells become rare, and even dis- appear altogether. 10th. That their strata are, by some, 'considered not to be precisely in the position in which they were formed. llth. That, as they contain no vestige of animal remains, they are considered to be the oldest rocks, and therefore are called primitive. In proof that the strata, as we approach the foot of lofty mountains, are not horizontal as in low hills, I shall present to your notice the section of a mountain in the Hartz Forest in Germany, drawn from the description given by Werner himself. This mountain is called the Brocken, (see p. 123,) and rises to about the same height as the most elevated mountains of England : but the result of the examination of its surrounding strata by Werner, affords sufficient evidence of the facts it discloses. The centre is of granite, which is, as it were, mantled all around by several successive and perfectly distinct strata, the oldest next to the primitive rock ; and invariably, each succeeding stratum, being newer than the preceding, dips lower and lower, as we depart from the primitive rock around which they are successively deposited. The nature of the several component masses of this nioun- 116 The Sea has deposited different tain, will be further noticed when we arrive at the con- sideration of the mineralogical differences existing in mountain rocks. The successive deposition of these strata (for that they were successive will become more apparent when their geological differences shall have been pointed out) may at least in degree be urged in proof that there have been repeated irruptions and retreats of the sea : they will more- over evince that the sea has not always deposited stony substances of the same kind., inasmuch as these deposits are distinct, and even essentially different, in their natures : and the strata surrounding this mountain may be brought in evidence, perfectly in agreement with numerous other observations, that the sea has observed a regular succession as to the nature of its deposits. From these circumstances, it is reasonable to infer that the sea has undergone great changes in the nature of its jiuid: whence we may presume that there may have been a succession of changes in the nature of the animals which inhabit it, corresponding with the changes in the chemical nature of the sea. That such changes have taken place in the nature of the inhabitants of the sea, we have abundant proof. Not only do the species and even genera of the shells change with the strata, but it is generally the case that the shells of ancient strata have forms peculiar to themselves ; that these forms gradually disappear ; that they are not found in the strata recently deposited, nor in the existing seas : but the more recent strata enclose some species which the moat experienced eye cannot distinguish from those which now inhabit the ocean.* The section of the Brocken mountain (see p. 123) shows the reason for our assertion that, as we approach the sum* mits of lofty mountains, the remains of marine animals and shells become rare, and even wholly disappear. It has * Of this latter assertion, a proof has already been adduced in the ' account of the alluvial deposit discovered on the banks of the Frith of Forth, p. 105, Rocks at different periods. 117 already been stated that granite, which forms the centre and summit of this mountain, is considered to be the oldest of rocks, because it is found underneath all others and frequently rises through and overtops all other the con- stituent masses of mountains, as well as because it never contains animal remains ; granite, in like manner, con- stitutes the highest parts of very many mountains of dif- ferent elevations throughout the globe. But it is often found that, although in some countries the sides of very lofty mountains have been covered by succeeding strata to a very great height; yet in other countries, primitive granite of very inferior elevation is exposed almost to the level of the sea, without having any part of it covered by secondary deposition ; and the fact seems to be that these secondary depositions have greatly varied in extent, in character, and in elevation. We now come to the consideration of the summits of lofty mountains which contain no vestige of a living crea- ture, and whose stratification, if it may be so called, differs from that of mountains of less elevation. The summits of lofty mountains generally consist of one or two, and sometimes of alternating, deposits of some of the older rocks ; which for the reasons already given have been termed primitive. Some of these rocks mostly assume one appearance; others have mostly an appearance wholly different: 1 say mostly, because there are but few rocks that always assume the same appearance in regard to stratification. For instance, some of the older rocks occur in regular and highly inclined strata ; sometimes have no appear- ance of regular deposition, either horizontal or inclined. The summits of lofty mountains, constituted of granite, seem composed of large and irregularly sized blocks, piled on each other without any appearance of order: while on the contrary, gneiss^ another primitive rock, is almost in- variably in strata, inclined at various angles to the horizon. This diversity in appearance is very considerably aug- mented in mountains consisting of alternate masses of 118 Mountains their primitive state and primitive compounds, which are by no means rare ; and as these rocks suffer in different degrees by long exposure to the action of the elements, this circumstance considerably contributes to increase the disorder of their rugged sum- mits, which often appear at a distance like the ruins of towers and of fortifications. Whether these constituent masses are still in their origi- nal position is a problem of no inconsiderable interest ; nor can we wonder that able geologists should differ on the subject. Cuvier, on the one hand, considers that the very appearances of their summits, are so many proofs of the violent manner in which they hate been elevated. He is of opinion that all the older strata of w hich the crust of the earth is composed, were originally in a horizontal position; and that they have been raised into their present highly inclined position, by subsidences that have taken place over the whole, earth. On the other hand, Jameson, (who is a rigid follower of the opinions of Werner, whence we may infer that it is also Werner's opinion,) believes that the present inclined position of these strata is, in general, their original position; an opinion which he considers to be countenanced by the known connection of strata, the phenomena of veins, the crystalline nature of the older rocks, and also by what he terms the great regularity in the direction of strata through- out the globe. Since, therefore, two authorities so eminent have not yet decided the point, and since their opinions are directly opposed to each other, we must be content to await and to expect an agreement, drawn from yet further inquiries amid the phenomena presented by the grand features of mountain rocks.* But the researches and experience of many skilful geologists, all unite in this : that the summits of many lofty mountains contain no vestige of animal or organic remains ; * Some further observations on this part of the subject will hereafter ,be made, in treating of the ' Internal Structure of the Earth.' and causes of elevation. 119 and are considered to be in their primitive state. An ap- proach towards these summits discovers that the sides are covered, or, like the Brocken mountain, mantled around to a very great elevation, by deposits enclosing sea shells and other organic remains. These are common in the lower Pyrenees, whose elevation does not exceed six or seven thousand feet above the sea : according to Ulloa, however, shells have been found at the height of 14,220 feet above the sea on a mountain in Peru. It is extremely difficult, it is even in most cases im- possible, to ascertain the internal structure of large and elevated mountains : but if on ascending them, it be found that their summits are crowned by certain rocks which are known never to include shells or other organic remains^ and which have never yet been found resting upon those rocks which do contain them it is assumed that we have a right to conclude, from analogy, that the same rock which forms the summit, composes the mountain itself, ascending from the base to the summit through the centre ; and that the masses of rock surrounding it, even to a great elevation, were deposited after the creation of the central mountain. We may, I say, conclude this to be the case from analogy, because in certain districts of the European continent, the operations of the miner have occasionally disclosed the fact. In various parts of Germany some mines are situated in lofty mountains. For instance, in the Krivan mountain, there is a gold mine, 6954 feet above the sea; and in the mountains of the Tyrol, a silver mine, 7512 French feet above the same level. We have now arrived at that branch of our subject which may be termed Mineral Geology ^ which has for its object the natures of, and differences existing m, the component masses of the crust of the earth. These masses were by Werner, divided into primitive^ transition, andjla>tz. PRIMITIVE ROCKS never contain animal or other organic- 120 Of Rocks their order remains, and are never found to alternate with, or to rest upon those rocks, which enclose animal remains. Primitive rocks are so named, because, in so far as we know, they are the oldest, and were the first formed. They have a crystalline appearance, and are therefore chemical deposits, principally composed of the siliceous- and argil- laceous earths. On the primitive rocks repose the TRANSITION ROCKS ; in ascending the series, these enclose the first appearance of organic remains of animals, none of which now inhabit the seas ; these rocks chiefly consist of chemical deposits, but amongst them mechanical deposits first make their ap- pearance :* they were termed transition, as forming a con- nection between the oldest and the newest rocks. On the transition rocks, reposes the extensive class of FLCETZ ROCKS ; the older of these contain the remains of sea fish approaching in character to the kinds found in the ocean, and the newer of them contain shells precisely the * The differeiice between a chemical and a mechanical deposit may be thus explained. A chemical deposit is the result of that law of nature which is termed affinity. Pounded flint, which is nearly pure silex, with a certain proportion of potash and of some other substances, when melted, forms a glass which is soluble in water. When thus dissolved, the mixture is called the liquor of flints. It is said that a quantity of this liquor was left in a bottle during eight years by Professor Siegling ; vho found that the force of affinity acting upon the particles of silex in the liquor, caused them to deposit transparent crystals of quartz, hard enough to give fire with the steel. These crystals were a real chemical deposit. A mechanical deposit is effected without the agency of affinity. If for instance sand or clay be mixed up in water, it will be deposited without regularity, or intimate combination, merely by its own weight. If this deposit be left to dry, and to become hard, it will not break in any par- ticular direction, nor will the particles of which it is composed adhere together very strongly. The earthy particles fall down merely by their own weight, without exerting any affinity for each other, and therefore without that regularity, or election, which in the former case produced crystals of regular forms j consequently this is a mere accidental or mechanical deposit. and succession. 121 fame as now exist in the sea. Flcetz rocks are for the most part, mechanical deposits. Such are the divisions which the observations of Werner in his own country induced him to adopt. Other geologists however, of at least equal experience, are of opinion that the division of rocks enclosing organic remains into two classes, transition and floetz, is unnecessary : they therefore term all those rocks which contain organic remains, ex- cepting those called alluvial, SECONDARY ROCKS : and they object to the division of the secondary into two parts as un- necessary, since the whole series contains organic remains ; and to the term floetz, because it is incorrectly applied, inasmuch as some of the earlier rocks in that division, do not lie in strata that are flat, which is the meaning of the word flcetz. We learn from what has preceded 1st. That the older rocks are principally composed of the siliceous and argillaceous earths. 2d. That the primitive parts of the crust of the earth are entirely chemical productions ; whereas, in the newer, we find a beginning, and in the still newer, an increasing quantity of mechanical depositions. 3d. That limestone occurs but sparingly in the primitive, more abundantly in the transition (or older secondary), and in the floetz class (or newer secondary) in immense quantity. 4th. That in the earlier deposits we rarely meet with bituminous or saline matters, as coal or slate, but that these occur in great quantity in the newer formations. But that part of our subject to which we are now arrived, viz. the consideration of the nature of the individual rocks or compound masses, which have been brought to light by the operation of the miner, or the researches of the geolo- gist, opens to us a field of inquiry of such amazing extent, as to induce me to pause, and, for a moment, to consider the precise nature of the object we have in view. Q 122 Rocks their order exhibited This, if I rightly understand it, is the acquisition of such knowledge of the great outline of geological facts and phe- nomena^ as the researches of men eminent in science have enabled us to attain ; avoiding on the one hand an attempt to enter with mineralogical exactness into the study of every geological compound, and on the other, the bare recital of a catalogue of geological names, which would not afford either interest or instruction. In the consideration of the nature of individual rocks, is involved the remainder of our geological positions. We proceed to the 12th. That rocks which, because they include no vestige of animal remains, are termed primitive, are of various kinds. 13th. That rocks enclosing animal remains are never found underneath, or supporting, those rocks which are termed primitive. 14th. That some primitive rocks alternate with each other ; but that granite is found beneath all others, and frequently overtops all the rest. 15th* That rocks which include organic remains must have been formed after the shells they contain, and therefore, not being considered primitive, they are, by some, termed secondary rocks ; whence the terms used by geologists of primary and secondary formations. 16th. That there are many varieties of secondary rocks, each of which has received a geological appellation. 17th. That there exists another class of substances, not appropriately termed rocks, but which, being con- sidered to be the debris, or ruin of rocks, by their long exposure to the action of air or water, or both, are there- fore termed alluvial and diluvial deposits. But before we proceed to examine these rocks indi- vidually, let us take some further notice (see page 115) of the interesting Section of the Bracken Mountain, situated in the section of the Bracken Mountain. 123 in the Hartz Forest in Germany, which throws much light on the subject of the relative position of mountain masses in general. A brief view of the nature of these masses will of course be comprehended in the succeeding descriptions of individual rocks. The centre of the mountain is granite (), on each side reposes another primitive rock called clay-slate (bb), which, (ts well as all the succeeding strata^ is found entirely to sur- round the granite. The two strata next in succession, (c, d c, d} are by Werner termed transition rocks, the first being limestone^ the next greywacke and greywacke-slate. The stratum resting on the latter is cajled by Werner, the old red sandstone (e e), and is the oldest of what he terms the floetz rocks ; the succeeding strata are also floetz rocks. On the old red sandstone reposes the 1st Jloetz limestone (ff) ; on it the \stjlostz gypsum (g g) ; then succeeds the Ind or variegated sandstone (h h) ; then the 2rc d or newer gypsum (it)', and lastly the 2nd limestone (k k). It is essential to be noticed that I do not pretend to give the precise extent, dimension, or shape of the granite forming the centre of this mountain, or of the several successive and incumbent strata ; their general shape and position is $11 that is intended to be conveyed. Nor must we forget to observe that, in reality, all the strata incumbent on the granite, are less and less in elevation as they are more and more distant from it, each newer deposit being lower than that preceding it in point of age and situation. Nor must we fail to remark that these several strata, which may be supposed to stretch along through a considerable tract of country, would soon assume that position which determined 124 Section of the Werner to give to the newer amongst them the term of floetz rocks ; that is to say, they would be flat) which i the meaning of the word floetz. On the 2nd limestone reposes the alluvial deposit (/Oj with the precise nature and extent of this, I am not acquainted.* This section has so greatly the appearance of order and of art, that it might be supposed to be the mere contrivance of some theorist to answer the particular objects of his invention : but we have no reason to suspect it. That Werner was in some sort a theorist can scarcely be denied ; but it must at the same time be allowed that it was his great object to develope a grand outline of the facts pre- sented by nature, and that his theory was wholly built upon investigations, to which the great mining and moun- tainous district in which he resided is particularly favour- able. A Cornish miner of observation and talent, but whose education and knowledge is principally confined to his art ; who had never read, or perhaps even heard of a theory of the earth, lately told me that, on examining a certain district in Wales, he was surprised to find on the side of a mountain, strata of various kinds in regular succession, and much more so to observe the same strata in the same order on the side of another mountain distant nearly 20 miles from the former. It was the more remarkable to him, be- cause Cornwall is not a distinctly stratified country. The section of the Brocken mountain has been selected, as being a well authenticated example of remarkable order in its several deposits, and because the relative position of rocks, and the order in which they succeed or cover each other, are curious and interesting departments of geological inquiry. If however we were to imagine that this forms a representation of the deposits of mountain masses in the aggregate, we should err. Though granite frequently over- tops other rocks, it is perhaps more frequently found that * In the above description the terms used by Werner, or his disciples, have been adhered to; they differ from the more modern nomenclature of the same rocks, which however in this case ifc unimportant, since the section is given only to illustrate the fact, that a certain degree of order exists in tho series of mountain rucks. Brocken Mountain. 125 other primitive rocks rest immediately upon and above it. Granite is sometimes observed to alternate with gneiss, and gneiss with micaceous schistus and clay-slate. Mont Blanc, which is 15,680 feet high, and is the highest mountain in Europe, is of granite nearly to the summit. It is said that, in the Andes, in South America, granite has not been seen higher than 1 1,500 feet above the level of the sea. A mountain called Marno, in Portugal, is* granite covered by clay-slate enclosing crystals of a mineral called the chi- astolite* The same rock enclosing the same substance, forms the summit of Skiddaw in Cumberland, probably resting also on granite, which however does not appear on the surface. It is sometimes found that several of the primitive rocks rest upon granite, and above these some of the transition or floetz rocks : or, as they have been conjointly termed by some geologists, secondary rocks. Even alluvial matter is said to have been observed, covering the summits of ele- vated mountains. But it has been objected to the rules laid down by Werner, in regard to the relative ages and positions of rocks, as forming mountain masses, that, as his observations have been chiefly confined to the country in which he re- sided, it is not reasonable to adopt the result of researches with regard to one district, as obtaining in every other country. This objection is well-founded. The observations of other geologists in other countries certainly are not all in perfect accordance with the rules laid down by Werner. This dissonance is attributable to various causes. Some actual exceptions to his classification have been discovered ; but occasionally, as it is reasonable to infer, these dis- agreements may be attributed in degree to the yet imper- fect state of the science, and to the want of precise defi- nitions in regard to the characters of many rocks. Some, which have obtained the same appellations, are so different in appearance, that the most experienced eye alone can determine their general agreement in regard to character and composition; while, on the other hand, certain others 126 Rocks of their succession generally. have obtained different names in different countries. In this imperfect state of geological language, the skill of the observer must always be had in consideration. If Werner was actually a theorist, he was one of a superior order. He extended his researches throughout the large and important district surrounding him. The relative age, deduced from the relative position, internal structure, and contents of'the great masses forming that mountainous district, seems to have been ascertained by him with a degree of certainty that defies the application of the term theory to his results. If he merit the name of theorist at all, it seems only to be in consequence of his assertion, or sup- posed assertion, (for hitherto his principal discoveries have been communicated only by some of his pupils) that the same results will be found to prevail universally. It is cer- tain that researches in almost every quarter of the globe, have tended in an astonishing degree to verify his opinions, that order in regard to deposition is universally prevalent, and that this order is never inverted. It cannot however be denied that theories built even upon researches into the phenomena presented by nature, have both advantages and disadvantages. They serve to induce research, inquiry and discussion ; which, when car- ried on with that temperate zeal which may be expected from men whose object is truth, will be sure to promote it. It were to be wished that the love of truth were thus pre- valent ; much needless and intemperate warmth would then be averted ; and were observers bent on this alone as their Xiltimate object, science would be benefited by nicer and more candid geological description than can be expected from those, whose great object is the support of a favourite theory. Inquiries into the nature of the globe contribute greatly to the advancement of real science : they serve at once to amuse and to instruct, by affording ample materials for reflection ; they force upon the mind an immovable con- viction that the globe itself was called into existence by a poiper^ whose design and contrivance are every where mani* fest : a poAver, whose immensity is unsearchable. LECTURE VI. . Of the arrangement of Rocks, and descriptions of them individually. WE shall now proceed to the consideration of individual rocks. In addition to the primary and secondary rocks already alluded to, there are others, which being of an origin obviously different to nearly the whole of the primary and secondary, are separated from them. I mean Trap Rocks, and Volcanic Rocks. Both these seem to be justly attributable to the action of fire on materials previously existing in the bowels of the earth, and have therefore been separated from the primary and secondary, and divided into two classes, as being the result of igneous action either at different periods, or under different circumstances. Per- haps however we ought not to consider it as a point actually decided that the trsp and volcanic rocks are the only ones justly attributable to the action of fire, for there are not wanting able geologists of extensive observation who qon- sider that even granite itself may have resulted from the same cause, and that its formation was probably of a date posterior to the rocks reposing on it. This may ever remain a matter of theory. The best arrangement of rocks seems undoubtedly to be that which is closest to the order in which they occur in nature ; the most instructive names for them, those by which they are commonly known : and I shall in the fol- lowing pages treat of them with these objects in view. Some few observations may not however be misplaced. It is not always possible to judge of a rock by a hand specimen ; to do this correctly, it ought mostly to be seen in its native place, that isj in connexion with such other 128 Rocks their arrangement. rocks as it is associated with in nature, for several diffi- culties present themselves. In the first place, it is extremely difficult in compound rocks to say what are the ingredients that ought to be esteemed essential to the rock ; that even when this can be done, it is no uncommon circumstance for one or more of its ingredients to be altogether wanting ; that on the other hand other incidental ingredients may appear ; that certain rocks of about the same age sometimes pass into each other so imperceptibly, that it seems impos- sible to say where the one begins and the other ends ; and such rocks are occasionally intermingled, or involved to- gether : hence cabinet specimens often do not afford the means of forming a correct judgment of the nature of an individual specimen, and hence also a perfect classification, or natural order is not to be expected : the science is still young, but it advances rapidly. TheRev.W.D.Conybeare, in his admirable'introduction to the c Outlines of the Geology of England and Wales/ to which introduction I would recommend the student's earnest attention, has however adopted a division of rocks into five Orders. This division seems at once natural and instructive. I shall therefore adopt it on the present occa- sion. His divisions (in a descending series, that is, be- ginning with the newest, and descending to the oldest) are, 1. The Superior order. 2. The Supermedial order. 3. The Medial order. 4. The Submedial order. 5. The Inferior order. The Superior comprises all above the chalk ; the Super' medial, the chalk and all between it and the coal ; the Medial includes the coal and some rocks intimately con- nected with it ; the Submedial, a large number of rocks chiefly slaty, lying below the preceding ; the Inferior, includes the lowest of all. To these must be added Trap rocks and Volcanic rocks ; Alluvium and Diluvium. I shall now cite the catalogue of the whole in their ge- nerally-accepted order, and under their separate divisions, and then proceed to give some description of each in- dividual. Rocks their arrangement. 129 SUPERIOR ORDER. 1. Upper Freshwater for- mation. 2. Upper Marine formation 3. Lower Freshwater for- mation. 4. Lower Marine formation or London Clay 5. Plastic Clay formation SUPERMEDIAL ORDER. 6. Chalk. 7. Green sand 8. Iran sand 9. Oolites. 10. Quadersandstein 11. Mmchelkalk 12. New Red sandstone 13. Magnesian limestone MEDIAL ORDER. 14. Coal 15. Mountain limestone 16. Old Red sandstone SUBMEDIAL ORDER. 17. Greywacke 18. Transition limestone 19. Greenstone 20. Qwarte roc. 21. 22. 23. 24. 25. 26. Serpentine Diallage rock Euphotide Clay slate Alum slate Whet slate Flinty slate Chlorite slate Talcose slate Steaschiste INFERIOR ORDER. 27. Hornblende rock Actynolite slate 28. Primary Red sandstone 29. Primary limestone Cipolin Ophicalce Caldphyre Dolomite 30. Mica-slate 31. Compact and Granulaf felspar Whitestone Eurite Leptinite 32. Gneiss 33. Granite porphyritic graphic Protogine Granite veins 130 Rocks Superior Order. TRAP ROCKS. 34. Wacke 35. Claystone Cloy porphyry Claystone porphyry Domite 36. Clinkstone Clinkstone porphyry 37. Compact felspar Felspar porphyry Hornstone porphyry Ophite Melaphyre Trachyte 38. Pitchstone Pitchstone porphyry 39. Basalt Basanite Basaltic porphyry 40. Augite rock Dolerite Mimose 41. IJypersthene rock 42. Amygdaloid 43. Cornean Aphanite Variolite Vakite Trappite 44. Greenstone trap Porphyritic greenstone 45. Sienite 46. Trap tuff VOLCANIC ROCKS. 47. Lava Volcanic amygdaloid 48. Obsidian Pear 1st one 49. Pumice 50. Volcanic conglomerate 51. Volcanic tufa 52. ALLUVIUM AND DILUVIUM. SUPERIOR ORDER. The rocks of this order principally consist of yery numerous beds of sand, clay, and marie, together with some of imperfect limestone; and some of these contain the remains of animals now existing, and of shells now inhabiting the seas ; but this agreement diminishes in de- scending through this series of beds ; in which are found alternating deposits by salt water (Terrain marin) and by fresh water (Saaswater formation. Terrain d'eau douce). The beds of this order comprehend the newest jflastz rocks of Werner, and the tertiary deposit of some authors. Ter- rain Tertaire* Terrain de sediment superieure of French geologists. Rocki Superior Order. 131 1. Upper Freshwater formation. This consists, in Headon hill in the Isle of Wight, in great measure of a yellowish white marie, enclosing more indurated masses, containing a greater proportion of cal- careous matter. It encloses very thin and friable fresh- water shells in great abundance, together with seeds, and parts of coleopterous insects : the bed is about 55 feet thick. In France the analogous beds (Troisieme terrain d'eau douce) consist, as has already been observed p. 101, of limestone and siliceous substances, as flint, pitchstone, and jasper, and containing freshwater and land shells, nearly all of which belong to genera now living in morasses. It extends 30 leagues to the south of Paris. Other forma- tions of the same nature occur in France, as at the foot of the Pyrenees, and near Aix at the mouths of the Rhone. Considerable tracts of it also appear in Italy and Spain, JN^orway and Iceland. 2. Upper Marine formation. The Crag of Suffolk has been considered as being the newest bed of this series. It appears at Walton on the coast, and near Harwich, forming the upper parts of the cliffs, resting on the London clay, and consisting of sand and gravel in regular beds enclosing shells, many of w r hich do not appear to differ from those now found in the neighbouring seas. The Crag, however, is by some geologists suspected to be diluvial. In other places, the beds of this formation consist in part of loose siliceous sand, or of sandstone : in the former state it composes the covering of Bagshot and Frimby heaths, and of Hampstead and Highgate hills \ in the form of sandstone it appears as the Grey Weathers in Wiltshire, and constitutes the largest masses of Stonehenge : in the sand have been found some shells, but too imperfect for decision as to their species ; they exhibit circumstances of agreement with those of the same beds near Paris (Deujcieme terrain marin) already noticed 1 32 Rocks - Superior Order. (see p. 100) as consisting of sand and sandstones containing oyster shells, on which rests a bed of clayey sand and marie containing the buhr stone or mill stone. Along the course of the Rhine near it junction with the Maine, both freshwater and marine beds are found. The same beds appear in Italy, Sicily, Dalmatia, and parts of Greece; Malta appears to be entirely composed of them. 3. Lower Freshwater formation. In Headon hill it consists of a series of beds of sandy, calcareous and argillaceous marles and limestone, with more or less of a brownish coaly matter. It contains only freshwater shells. In France, as already noticed, this for- mation (Deuxieme terrain d'euu douce. Knockenfuhrender Gyps) consists of gypsum and marie, and contains the bones of extinct quadrupeds (see p. 100), amphibious ani- mals, and shells, which are of land or freshwater species. It is remarkable as containing also the bones of birds. 4. Lower Marine formation. London Clay. The London clay consists of a bluish clay, but more or less of the ordinary clay colour near the surface, and some of the lower beds are yellowish white or variegated, having a soapy or unctuous feel, and approach more nearly than the upper to the nature of marie, since they effervesce when vinegar is thrown on them. This formation occasionally includes beds of sandstone, or of a coarse argillaceous limestone of which Parker's Roman cement is made : and which more often appears in the form of nodules (Septaria) and in regular layers : these frequently contain wood, which sometimes has the appearance of having been charred, and also shells exhibiting the pearly lustre. It contains also the bones of the crocodile, turtle, vertebral fish, the lobster and crab ; the casts in wood of an animal considered to be analogous to the teredo navalis or borer of the seas sur- rounding the West India islands. In it also have been found 700 specimens of fruits or ligneous seed vessels. It Plastic Clay formation. 133 is a very extensive deposit, forming the greater part of Middlesex, the \vhole of Essex and Suffolk, and a part of Norfolk, and frequently almost to the very surface. In France it consists of a coarse limestone (Calcaire grassier) abounding in marine petrifactions, and affording the ma- terials for many of the buildings of Paris. A series of specimens lately presented to the Geological Society from the Plain at the foot of the Ilimmaieh mountains exhibit a close agreement in character with those of the London clay. The whole suite of beds constituting this formation has been termed by some French geologists, Premier ter- rain rnarin ; by the Germans, Ceriten Kalkstein. 5. Plastic Clay formation. This in England consists of a variable number of sand, clay, and pebble beds irregularly alternating, forming to- gether the lowest formation of the superior order, lying immediately on the chalk, and containing some appearances of coal decidedly of vegetable origin, pyrites, green earth, and nodules of dark coloured limestone in some places. It contains the shells of oysters, several other shells, the teeth of fish, and occasionally woody fibre, and even the branches and leaves of plants. It skirts the London clay within the London chalk basin, and also appears in the Isle of Wight; it is therefore very extensive. In France, where it was first noticed, it appears to consist of two beds of marie or clay, the lower of which is used in pottery (Argile plus- tique. Plastischer Thon) 9 having a bed of sand between them, and contains some shells, which seem to be con- sidered as of freshwater origin, since these beds have been denominated (reckoning from the chalk on which they lie,) Le Premier terrain tfeau douce. The sand beds of the plastic clay form the grand reservoir of soft water for the supply of the deep wells in and around London ; but the greater part of those of London itself afford hard water, from the great bed of gravel on which London is for the most part built. 134 Rocks Supermedial Order. The beds termed Molasse and Macigno, covering the great basin of Switzerland between the lakes of Anneey and Constance, consist of sandstone Avith lignite, and be- long to the Plastic clay formation. The Nageljluhe of Switzerland consists of calcareous and siliceous fragments, rounded, and agglutinated by a calcareous cement. The Nagelfluhe and the Molasse have been observed to alternate with each other. SUPERMEDIAL ORDER. This order includes the Chalk, and all the beds between it and the Coal, consisting of sand and clay and limestones. They correspond with ihe.Flcetz class of Werner, in which however are sometimes included the coal strata; but the word floetz or flat, as applied to some of them, is not always correct; for though the beds of these rocks mostly lie at a small angle with the horizon, and in that case are nearly flat, they are on the borders of the Alps usually in highly inclined and contorted strata. All the beds of this order contain the remains of sea animals. The beds be- tween the chalk and the coal are sometimes by French geologists included under the term Terrain secondaire ; the Flats gebirge of the German school. Chalk. This substance is too well known to need an accurate description of it here ; the purest kind consists of about 47 per cent of lime, and 43 of carbonic acid. It often contains sand, especially in the lower beds, thus passing into a coarse limestone (ragstone) ; and numerous organic remains and layers of flint in the upper, together with others of hard chalk marie of a yellowish colour : in the lower, few or no flints appear; it is therefore commonly divided into the Upper Chalk (Craie blanche, ou superieure) and Lower Chalk (Craie Tufau) ; together, the Kreide formation of the Germans. We have manifest proofs in our own coun- Chalk. 135 try that this deposit must have suffered extensive ruin at remote periods and by the action of deluges, for the vast beds of gravel with which the roads are mended around London, and which have been rounded by attrition, were once lying in the chalk ; for being heavier than the chalk itself, they were left when the chalk was washed away. The only mineral substance found in chalk, is iron pyrites: among other remains of animals, it sometimes contains the teeth of the shark, the grinding palates, and vertebrae and scales of fishes, ammonites, oysters, echinites and sponges. In England, chalk extends with little interruption from the Coast of Yorkshire to that of Devonshire, while a line of hills extends from Wiltshire to the Coast of Kent ; and a branch from the centre of the latter ranges to the Sussex Coast near Brighton. In Europe, the chalk extends from the Thames through France, and Poland, into Russia, and thence to the south of Sweden, is said to occur near the mouth of the Elbe, thence at Flamborough Head in York- shire, and thus completing a circuit which may be termed the Chalk basin of Europe. It is found in Ireland, and Spain, but its existence is scarcely known out of Europe : it has not been found either in North or South America. Before quitting the account of the chalk it should be noted that in England the lower bed passes into a grey colour termed Grey chalk or Chalk marie ; it contains some silex and alumine : it appears abundantly in the bottom of the cliffs west of Dover, and probably derives its colour from some intermixture of the Blue marie underlying it ; which is seen at Folkstone, and which reposes on the green sand. It is the Craie Inferieure of the French. 7. Green Sand. This consists of loose siliceous sand, and of sandstone having a calcareous cement ; both contain green particles, supposed to be a suboxide of iron, occasionally mica and coarse limestone (Kentish rag), and chalcedony near Char- mouth in Dorsetshire, and beds of fullers' earth near Nut- field in Surrey. It contains numerous organic remains, aa 136 Rocks Supermedial Order. Ammonites, Nautilites, and many univalve and bivalve shells, and beds and masses of chert. It appears almost every where in England underlying the chalk, and in Surrey rises in Leith hill to the height of 993 feet. It appears also in France rising from beneath the chalk, and is believed to exist on the northern borders of the Alps, where the highest beds of a chain of calcareous mountains consist of a dark coloured limestone often mixed with green particles and agreeing in its fossils with our Green sand. The Green sand appears to be the Glauconie crate- use of the French \ who however sometimes include it and the iron sand under the designation of Ores et sables verts et ferrugineuses. Between the green and iron sand lies a bed of clay, often of considerable thickness, including masses of coarse limestone containing shells, which are believed to be of freshwater origin^ and as this clay is known only in Eng- land, and prevails most in the Wealds of Kent and Sussex, it has received the name of Weald clay. 8. Iron Sand. This Deposit, separated from the green sand by the Weald clay as above noticed, consists of a series of beds of sand and sandstone occasionally alternating with beds of clay, loam, fullers' earth, and ochre. The sand is sili- ceous, and coloured brown by oxide of iron, which in some places in Sussex prevailed so greatly, that some beds of it were formerly wrought as ores of iron. Some also contain fossil wood, and layers of wood coal, which caused very expensive and abortive workings in some places for coal, as at Bexhill in Sussex. Impressions of ferns have also been found in one spot. Fullers' earth occurs in it in Bedfordshire. It contains several shells and organic re- mains similar to those of the green sand. In England, it exists very abundantly, and in the Isle of Wight. In Sussex it is perhaps 500 feet thick. It occurs pretty abun- dantly in France in a similar geological position. Oolitfg. \ 37 9. Oolites. The oolites lie immediately beneath the iron sand in the midland counties of England. Their name is derived from the texture of the rock, or rather from the form of the par- ticles constituting it, which are somewhat egg-shaped, as is manifest in the Bath stone. The oolites consist of a series of oolitic limestones, of calcareo-siliceous sands and sand- stones, and of argillaceous and argillo-calcareous beds, alternating together, and generally repeated in the same order. They have been divided into three systems by the Rev. W. D. Conybeare ; the oolitic rocks of each system generally forming a distinct range of hills, separated from those of the other systems by a broad argillaceous valley. Upper system. Argillo-calcareous; Purbeck strata Oolitic strata of Portland, Tisbury, and Aylesbury Calcareous sand and concretions of Shotover hill, &c. Argillo-calcareous formation of Kimmeridgs and the Vale of Berks. Middle system. Oolitic strata associated with the Coral rag Calcareous sand and grit Great Oxford clay. Lower system. Numerous Oolitic strata, occasionally divided by thin argillaceous beds ; including the Cornbrash, Forest marble, Schistose oolite and sand of Stonesfield and Hinton, Great oolite, and Inferior oolite Calcareo-argillaceous sand, supporting and passing into the inferior oolite Lias and Lias marie, constituting the base of the whole series. It is not my intention here to enter into many particu- lars respecting the numerous beds above cited ; their general characters have already been given. It may suffice then to add some few notices, chiefly relating to the organic remains enclosed in them, some of whioh are of very re- markable characters. The Purbeck beds contain impres- sions of fish and fossil turtles, and remains of the crocodile, together with a shell supposed, but not ascertained, to be of fresh-water origin. Many shells are found in the Port- 138 Rocks Super medial Order. land beds, as well as in the Kimmeridge clay, which like- wise contain the vertebrae and paddles of an extinct animal termed the ichthyosaurus^ from its partaking of the nature both of the fish and the lizard, which also have been found in the beds of calcareous grit belonging to the coral rag, together with many shells, and a small species of coral giving the name to the bed. The Oxford clay also con- tains, though rarely, the bones of the ichthyosaurus, to- gether with many shells. The Stonesfield slate contains bones believed to belong to the opossum tribe ; of the cro- codile; of an immense animal which must have been 40 feet long and 12 feet high, and of which the lower jaw, vertebrae and extremities are in the Oxford collection ; remains of two or three species of tortoise; vertebrae of fishes ; leg and thigh bones apparently belonging to birds ; several cases of the wings of the beetle tribe^ and two or three varieties of the crab and the lobster. The remains of crabs and lobsters, and a multitude of shells also occur in the beds of the Inferior oolite : large fragments of wood are common in some of the upper beds. The lias contains the remains of the bones of large but extinct species of the lacerta or lizard, which lived entirely in the sea; of the ichthyosaurus and plesiosaurus ; the turtle; fishes, crabs 3 and a very great number of shells. The Oolites in England occupy a zone thirty miles in average breadth, extending across the island from Yorkshire on the north-east to Dorsetshire on the south-west. The lias alone, of the whole series, occurs in Ireland. In France, the oolites (Calcaire de Jura,) and the lias (Cal- caire a gryphites^) abound, circling the outer limits of the Chalk basin of Paris : they appear abundantly in the ex- tensive chains of the Jura mountains (Jurakalk formation ,J which principally consists of the oolite and lias : they are also found in the Tyrol, Switzerland, and generally through the Alps ; in the central parts of Germany ; near Moscow in Russia, and in Spain; but there are no observations tending to shew their occurrence beyond the limits of Europe. Quadersandstein. 139 10. Quadersandstein. This sandstone is of a whitish, yellowish or greyish colour, very fine grained, with an argillaceous, or a quartz- ose cement, Avhich is almost invisible, and sometimes con- tains a little mica : it occurs in beds lying nearly flat. It contains marine shells, and also, it is said the wood of the palm tree, and the impressions of leaves, and small deposits of wood coal ; in these respects, as well as in its colours, it differs from our new red sandstone, which is entirely with- out organic remains. It is found abundantly at the foot of the Hartz and other places in Germany, and at the foot of the Pyrenees, but is not recognised in England. It may be cited as a remark- able instance that many formations are wanting in par- ticular spots, that near Freyberg in Germany, the quader^- sandstein is said by Humboldt to lie immediately on gneiss. Humboldt observes that the geological position of this sandstone is below the great oolite formations, and is sepa- rated from the great variegated sandstone (new red sand** stone) by the muschelkalk. 11. Muschelkalk. The Muschelkalk, sometimes termed Shell limestone^ is whitish, greyish or yellowish, but the colours are always pale, and the fractured surfaces are always dull and com- pact : it sometimes contains veins of calcareous spar : and occasionally the beds are marly, arenaceous, or possess in some degree an oolitic aspect : it contains nodules or layers of hornstone passing into a sort of jasper, but beds of clay are rare : in Germany, it contains a little fibrous gypsum, coal with aluminous slate, and a great variety of shells, partly broken : it is observed by Humboldt that although the genera of these shells are the same as those of the lias, the species differ. It covers a vast part of the north of Germany, and -in the south of it extends over the whole table land between Hanau and Stutgard : in France, around the whole chain of the Vosges. It does not appear to have s 2' 140 Recks~-Supermedial Order. been yet recognised beyond the limits of Germany and France. 12. New Red Sandstone. The texture of this formation in England is very various. It appears sometimes as a reddish or variegated marie or clay, sometimes as a sandstone, in either case exhibiting streaks of light blue, verdigris, or cream colour (Gres bi- garre, Gres rouge, Fr.) ; sometimes these are interstratified, or pass into each other, and it is associated with, or con- tains beds of, a conglomerate, consisting of masses of dif- ferent rocks cemented by marie or sand. The sand of this formation is occasionally calcareous, sometimes of a slaty texture ; and is remarkable for containing masses or beds of gypsum, and the great rock salt formation (which will be separately noticed hereafter,) occurs within it, or is subordinate to it. No organic remains have been found either in the sand or sandstone ; but the magnesian sand- stone underlying it (presently to be noticed), and which is connected with the sandstone by the Rev. W. D. Conybeare, contains the remains of marine animals. In some places it contains sulphate of strontian and of barytes, and perhaps also in one place, but not certainly, ores of copper, grey cobalt, and black oxide of manganese. In England this formation is very extensive, since it constitutes its great central plain, from which it extends north through the counties of York, Durham and Nor- thumberland, and south quite to the coast of Devon and Dorset : opposite the coast of Devon the new red sandstone appears in France, accompanied by the oolites and lias, and by salt springs and gypsum underlying the Jura chain. In Spain at Cardona, enclosing rock salt and gypsum. It encircles the Vosges and the German chains of the Black Forests and Bergstrase (Buntersandstein) ; appears in the north of Germany, the Alps, Saxony, Silesia, Bohemia, and in Poland and Russia : the great desert of Persia is of a brick red colour and abounds in salt. In North America it is very abundant in the plains of the Mississippi, and it New Red Sandstone. 141 is observed by Humboldt that beds of marie containing gypsum extend over vast tracts of meridional America, covering a conglomerate. The conglomerate forming the lower beds of this forma- tion, appear in England in the north of Somerset, near Watchett; the nodules, which sometimes seem to be rounded fragments, consist of varieties of greywacke, and of a limestone frequently enclosed in it ; and this con- glomerate wholly composes the great valley west of the Quantock hills : near Honiton, in Devonshire, it contains pebbles of two or three inches in diameter, and approaches to a conglomerate pudding-stone : near Heavitree, it in- cludes crystals of felspar, chert, greywacke, rolled masses of porphyry, and white steatite. This conglomerate ap* pears to be almost identical with the Rothe todte liegende of Germany, which in the Hartz consists of fragments of whetstone slate, grains of felspar and quartz ; and in Saxony, of fragments of clay-porphyry, clay-slate, and mica-slate : these rocks are the Psammite rougeatre of Brongniart. The Puddingstone (Poudingue) of the same author appears to be a nearly similar rock, since it consists of tolerably large uncrystallized masses agglutinated by a paste, as of calcareous spar, petrosilex, &c. ; in the Breccia of the same author, the fragments are angular. , This conglomerate abounds in Germany (Porphyr gebirge. Porphyr secondaire. Porphyr de gres rouge) and Saxony. Humboldt remarks that the Rothe todte liegende of Werner is observed wherever man has excavated even a few feet in depth, over an extent of many thousand square leagues in meridional America. It consists of rounded frag- ments of quartz, siliceous schist, and lydian stone, cemented by an olive brown ferruginous clay, frequently covered by beds of the red marie as above stated. 13. Magnesian limestone. This limestone differs in several respects from common limestone, but principally in this, that it contains about 20 per cent, of magnesia. The texture is sandy, colour yel- 142 Rocks Supermedial Order. low, or buff, or fawn, or salmon, with a glimmering lustre; occasionally it is fetid, and sometimes a bed occurs of an oolitic character; occasionally the lower beds are blue, affording an excellent lime, sometimes cellular, and then closely resembling the rauchwacke of the continent. Such are the general characters of this formation in England, where it contains but few organic remains, as a few shells and the impression of a fish. It may be remarked that its organic remains alone would serve to distinguish it from the limestones of older formation. In this country it is associated with a conglomerate limestone, often exhibiting distinct fragments of the older mountain limestone, and passing gradually from an aggregate compound of very large pebbles of this rock, to one in which the grains are so small as scarcely to be distinguishable. Strings of galena have been observed in the magnesian limestone in Nottinghamshire and Durham ; and calamine, blende and galena in the conglomerate on the Mendip hills in Somer- set ; but it is supposed that these minerals may be derived from the older beds of which this conglomerate is com- posed ; many of the principal mines in that district are however in it. In England, the magnesian limestone is chiefly found forming a range of hills extending from Sunderland to Nottingham. It overlies the coal in Northumberland and Durham and at Whitehaven, and the conglomerate con-r nected with it is found in Gloucestershire and Glamorgan- shire. On the continent the magnesian limestone (Cahaire Alpin of French geologists, Alpenkalkstein of the Germans, the Zechstein of Humboldt,,) constitutes large mountain zones encompassing the Alps, and in the Vosges vast masses of its conglomerates invest the primitive chains, and those of Germany. It is found largely in France and in the Andes of Peru. Coal. 143 MEDIAL ORDER. This order includes the Coal-measures as they are geo- logically termed, the mountain limestone on which they rest, and the subjacent old red sandstone. These rocks probably belong to the transition series of Werner, since the beds of the two latter do not commonly lie flat, but are inclined at considerable angles with the horizon, in an economical point of view, this order is the most important of the whole. What would England be without its vast deposits of coal, and without the iron with which some of them abound ? The mountain limestone moreover furnishes a vast proportion of the 30,000 tons of lead annually raised in this country, and a small proportion of zinc and copper. 14. Coal measures. The Coal measures, (Terrain Houillier of the French, Steinkohlengebirge of the Germans,) consist of a series of alternating beds of coal, slate clay, (Argile schisteuse ; Schieferthon) sandstone (Gres des Houilliers ; Kohlensand- stein) ; and together form the independent Coal-formation of Werner. Coal is rarely found in sufficient quantity to allow of its being wrought for economical purposes except in this for- mation ; that of other formations is mostly of very inferior quality. This coal is distinguished by its quantity of bitumen, of which it yields from 20 to 40 per cent., the remainder being carbonaceous matter with a small propor- tion of earth. The beds of coal in England do not commonly exceed six feet in thickness ; but in Staffordshire, where several beds come together, it has been found of about 30 feet in thickness. The beds of Slate-claj lying between and among those of coal and sandstone differs from the clay-slate of the old rocks in being les solid and hard. 144 Rocks Medial Order. The Sandstones are generally gritty, micaceous, and tender ; they afford freestones for buildings, whetstones, grindstones, flagstones, and paving stones ; and when the layers are very thin, roofing slates. In the Slate-clay are frequently found beds, or layers, in the form of nodules, of Clay-ironstone ; being an impure carbonate of iron, yielding about 30 per cent, of metal. At the bottom of the whole series of coal, shale and sandstone, lies a bed of coarse grained sandstone termed the Millstone- grit) consisting of particles of quartz of various sizes, held together by an argillaceous cement, and having often the appearance of a rock composed of the ruin of some of the older rocks, since rounded particles of felspar may occasionally be seen in it : this sandstone, and this only of those connected with the coal, is occasionally found to contain veins of lead-ore, and the beds of shale enclosing vegetable impressions sometimes connected with it yield clay-ironstone, sometimes containing mussel shells. The organic remains of the coal measures consist of the trunks and leaves of trees, and more rarely of the seed- vessels, all distinguishable from recent species, and appa- rently belonging to hot climates and moist situations ; the trunks, being those of large reed-like vegetables, are some- times in a horizontal, sometimes in a vertical position, to the height of 15 feet or more, as may occasionally be seen in the cliffs of the Durham and Northumberland coast. In the middle of the series of Derbyshire beds is a layer of ironstone containing so great abundance of mussel shells^ as to be distinguished by the name of Mussel-band. Several other shells, most of which are considered as being of marine origin, occur in the beds ; but two or three, amongst which is a variety of mussel, are suspected to be freshwater shells : the clay ironstone rarely contains galena and iron pyrites. In the Northumberland and Durham coal measures, 40 beds of coal have been seen, the two thickest of which are 6 feet and 6 feet 6 inches. Dr. Thompson calculates that this great formation alone, which is 23 miles long north Mountain Limestone. 145 and south, and 8 miles east and west, annually exports two millions of chaldrons, and that there is still enough left for the consumption of 1000 years. But besides the deposits of coal extending through a large portion of the above counties, we have also considerable deposits in Yorkshire, Derbyshire, Cumberland, Lancashire, Warwickshire, Staf- fordshire, Shropshire, Gloucestershire, Somersetshire, and in South Wales. Coal is also found in Scotland and Ireland, abundantly on the continent, in Sweden, in the centre and south and north of France, in the Netherlands, Germany, Saxony, and Bohemia. Coal is said to occur on the north of Con- stantinople, and indications are said to exist in Russia : it has long been worked in China, and has been found in Van Dieman's Land, and plentifully in the plains of the Mississippi in North America. It occurs in South America in red sandstone, rising to 1360 toises above the level of the ocean in Santa Fe de Bogota, in the salt plains beyond the tropic in New Mexico, and near the mines of Pasco in Peru at the height of nearly three miles above the sea level. 15. Mountain, or Carboniferous Limestone. The coal measures and millstone grit, forming the sub- jects of the preceding article, repose in England, and generally speaking in other countries, upon the Mountain limestone, which obtained its name from its generally form- ing hills of considerable elevation : in Ireland however, it is remarkably the reverse, being low and comparatively flat. The name of Carboniferous limestone has been pro- posed for it by the Rev. W. D. Conybeare, since it is not only the supporting rock of the coal measures, but also often includes beds of coal. This rock is mostly imperfectly crystalline, but is hard and susceptible of polish; its colours are various tints of grey, greyish blue and black, occasionally also red. When pure it consists solely of carbonate of lime, and some of its purest beds afford 96 per cent, of it : some beds contain a portion of magnesia ; others are oolitic ; sometimes it is T 146 R oc ks Medial Order. bituminous or fetid. The beds are frequently separated by thin layers of clay, or by gritstone, or shale, and in Derby- shire and the north of England by toadstone. Layers and nodules of chert occur in it like those of flint in chalkj and in every part of the world where it is found it presents large caverns and fissures, engulphing rivers and affording them subterranean courses. This limestone is the principal depositary of lead in England ; it also affords the ores of copper and zinc, but far less abundantly. Of organic remains it contains a great abundance, and they are very distinguishable from those of the superior beds, being mostly of distinct genera and belonging more to those formations which have been termed transition. This rock is frequently the Calcaire de transition of French writers. Sharks teeth, the vertebrae and palates of fish, and a considerable number of shells, of coralloids and encrinites are found in it. This limestone forms the base of the principal coal beds of this country, and since it sometimes crops out to the surface all around them, such deposits have received the names of Coal-basins. It is found abundantly in other countries, as in Germany, Bohemia, and in North America. 16. Old Red sandstone. The carboniferous or mountain limestone reposes on the old red sandstone, (Gres ancien y Fr.) but is often sepa- rated from it in England by a limestone shale. This sandstone appears to owe its origin to the ruin of the older rocks, and is coarse grained, micaceous, and evidently of mechanical origin : it contains fragments of quartz, clay-slate, flinty-slate, &c. ; and the clay forming its occasional cement is considered by some to be dis- integrated felspar : it is often schistose, and affords paving slates : its lower beds are often finely slaty, and pass into greywacke slate ; hence it is by many geologists believed that the old red sandstone is so closely allied with grey- wacke, the next rock in the series, that they are considered Rocks Submedial Order. 1 47 to be identical by some. The old red sandstone now and then passes into a quartzose conglomerate.) and sometimes appears as a sort of breccia. When more finely sandy or clayey it is difficult, if not impossible, to distinguish the old from the new red sandstone ; in general, however, the consolidation of the former is much greater than that of the latter rock. It contains no mineral beds or veins, and is generally destitute of organic remains, but in some of the lower beds of fine slates it contains a few .fossils resembling those of transition limestones. In England this rock is most abundant in the vicinity of the Coalfields of South Wales, and forms an immense tract in Brecon, Monmouthshire, and Herefordshire : it also occurs in the north of England, and in Scotland reposes on granite. It does not appear to be a rock of frequent or extensive occurrence on the European continent, but Beudant is said to have recognised it in Hungary in the transition limestone of Neusold, which lies on coarse- grained greywacke. It is included among the rocks des- cribed under the latter name by Humboldt. SUBMEDIAL ORDER. These, generally speaking, consist of slates or slaty rocks; but hitherto their limit has not been defined by the Rev. W. D. Conybeare, whose divisions we are attempting to follow. In the long list of rocks now included in this order, there may be several which ought perhaps to be ranged in the inferior order ; and it may be added that, highly de- sirable as it would certainly be to place these rocks in the order in which they occur in nature, it would be extremely difficult if not impossible so to do with precision, since many of them are associated with, or pass into, one another, or are so intermixed and interstratified, as to defy cer- tainty in this respect. We may however assure ourselves that ,the uppermost of the series is greywacke. T2 148 Rocks Submedial Order. 17. Greywacki. This rock as described by the Wernerian school appears to be a sandstone or gritstone, composed of grains of quartz? of flinty-slate, and of clay-slate, agglutinated by an argil- laceous cement of the nature of clay-slate ; the enclosed grains being sometimes very small, sometimes of the size of a nut. The old red sandstone, as is observed in noticing that rock, passes into, if indeed it be not a mere variety of, greywacke, which sometimes contains imbedded felspar in crystals or fragments more or less rounded, and has therefore a porphyritic aspect; sometimes also fragments of jasper, clay-slate and quartz are united by a siliceo- argillaceous cement; that of Charnwood forest contains oc- casional crystals of Cleavelandite. Greywacke is in part the Phyllade of Brongniart ; the Traumate of Daubuisson ; and constitutes a part of the Psammite of the French, but in this term are included varieties of sandstone, as for instance the coal grit : the Mimophyre of that school seems to be a variety of this rock; which is the Grauwacke of the German school, and is by Dr. Mac Culloch included in the generic term Argillaceous Schist. The name of this rock was given by the German miner, who termed every one he did not know wackcy adding in this case grau (grey) from its general colour. It contains occasionally some organic re- mains, as of shells, on the summit and around the base of Snowdon in North Wales ; sometimes also the remains of vegetables. Its strata are greatly subject to contortions. Greywacke is associated and often interstratified with slate (Greywacke slate; Schiste traumatique ; Phyllade intermediate ; Schiste de transition; G rauwack ens chief er) which it is impossible sometimes to distinguish from clay- slate ; this in its more simple state, appears to consist of a species of indurated clay, frequently of a greenish colour, and which, being laminated, splits pretty readily, or the laminae sometimes separate by exposure ; the colour of the green varieties, when thin pieces are held between the eye and a strong light, appears to be owing to minute specks of chlorite ; the colours are sometimes grey or purple or blue, Transition Limestone. 149 and when some of these varieties are broken across the laminae, the appearance is altogether that of chlorite. Grey- wacke-slate often passes into chlorite-slate, and when the green variety is much harder, into a variety of flinty-slate, which sometimes resembles compact felspar : when more compound, it contains mica either mixed or in layers. Greywacke mostly occurs in thin beds lying in the slates belonging to it. It occasionally includes beds and masses of talc ; of the whetstone ; of serpentine (?), quartz, alum- slate, or of compact felspar (?). It is a widely distributed rock. In England the slates of Charnwood forest appear to belong to this rock and those of the mountainous districts of Wales, and in part those of the north of England, hence our roofing slates are mostly greywacke slate : they occur in Cornwall, though not with certainty in the mining districts of that county ; they abound in Germany, and in that country, though in this but very sparingly, greywacke affords abundantly both veins and beds of metalliferous ores, as of silver, copper, lead and zinc : in Transylvania, of gold. It occurs in various other parts of the European continent, as in the Pyrenees and the Alps, and in Mexico, &c. 18. Transition limestone. This limestone is readily distinguished in its natural place, by that position ; and in well characterized hand specimens by its organic remains; these will be found in the general of a nature differing from those of the moun- tain limestone. It is commonly fine grained, the crystalline particles of which it is composed being small ; it has there- fore generally a more compact aspect than the mountain limestone. Its colours are various, it is often blackish, and is traversed by numerous thin irregular veins of calcareous spar. It furnishes some of the best ornamental.marbles. The organic remains it contains, are zoophytes, madrepores, millepores, trilobites, &c. ; but animal remains are not very common. It sometimes encloses quartz, lydian stone, and mica. It occurs in the form of beds in the slates belonging 1 50 Rocks Submedial Order. to greywacke and alternating with them. It is the Calcaire de transition, or Calcaire intermediate of the French. Transition limestone occurs in the slaty rocks of the north of England, and is found also in Wales and the west of England. It occurs in the Alps and Pyrenees, the south of France, the Hartz, &c. 19. Greenstone. Greenstone is a granular rock, principally composed of hornblende and felspar, but sometimes it includes quaitz, and occasionally calcareous spar. Greenstones occur under circumstances so very different, that there is a very great difficulty attending some of them ; of others the origin is manifestly igneous, and these are ranked among the trap or overlying rocks. Greenstone is however sometimes found under circumstances in which it would be difficult to assign to it such an origin, as for instance, lying upon and inter- stratified with the (Greywacke ?) slates of North Wales, as in the upper regions of Cader Idris and other mountains. It also occurs in the slates of the North of England. In the former at least the greenstone is often in long prisms, on the top of which lie, nearly in an horizontal position, slates not distinguishable from ordinary clay-slate, sur- mounted by other prisms of granular greenstone. This rock in Wales sometimes loses almost altogether the horn- blende, and then resembles a hornstone, which occasionally enclosing crystals of quartz, appears then as a porphyritic hornstone : it is sometimes finely granular and slaty, (green- stone-slate). It is found also in the slates of other coun- tries, as in Brittany and the Pyrenees. The general colour of the mass is green, as its name imports, the green of the hornblende being more or less communicated to the quartz. The Hemithrene of Brongniart is a rock composed of hornblende and limestone, occurring in the Hartz and in Saxony. The Greenstone noticed in this article, being connected with Greywacke and Greywacke slates, is not of Serpentine. 151 course to be considered as a primitive rock. Lower in the series will be found some notice of a rock essentially compound of the same materials, and which is commonly associated with those rocks which are included under the term Primary, and this, for the sake of distinction, will be described under the designation of Hornblende Rock. The Diabase^ Diorile^ and Amphibolite of French authors, and the Grunstein of the German school, seems to include both Greenstone and Hornblende rock. 20. Quartz rock. This rock is occasionally of pure quartz ; when compact it has sometimes a cement of quartz ; it is but rarely crys- talline, being more commonly obscurely granular. It is sometimes composed of quartz and felspar, occasionally of quartz and some mica, and then has a strong affinity to mica-slate. Its cavities sometimes include crystals of quartz, yet in the estimation of Dr. Mac Culloch the structure of this rock is obviously reunited, therefore mechanical ; it sometimes includes fragments of clay-slate, jasper, mica- slate, and even rounded pebbles, and hence its occasional passage into greywacke; yet it is found alternating with clay-slate, mica-slate, and gneiss, and is therefore an im- portant member of the primitive series. It is of various colours, white, ochreous, reddish, or dark purple. It is a stratified rock. It occurs in several of the Western Islands and in Scot- land, in Brittany, and from the description of Humboldt, quartz rock may be assumed as being plentiful in South America. It is the Quartz en roche and Quartzite of French authors, the Quarstein of the Germans. 21. Serpentine. Serpentine (Ophiolit, Fr. Serpentin^ Germ.) is a rock of considerable hardness, generally partaking of a green colour, sometimes however intermixed with red ; its frac- ture is dull, splintery, occasionally earthy, rarely approach- 1 52 Rocks Su bmedial Order. ing to conchoidal : some of the greenest varieties are the hardest, probably from the intermixture of siliceous mat- ter. It occasionally encloses masses approaching in character to noble serpentine. Some of the softer varieties pass into potstone. It occasionally includes veins of asbestus, and in North America, and Unst one of the Shetland Isles, hydrate of magnesia, and veins of soapstone in Cornwall. Daubuisson considers the basis of this rock to be talcose ; it contains a proportion of magnesia. In Shetland, and in Provence, it contains chromate of iron ; in Cornwall, veins and masses of native copper : garnet, hornblende and mica have been observed in it. It occurs abundantly in Cornwall, and at Trceblitz in Saxony : in the latter it reposes on gneiss, and also in the Alps associated with the oldest rocks, and is common in the mountains of the centre of Germany, and in South America. Humboldt observes that its transition into greenstone cannot surprise those who have studied the mountains of Franconia and Silesia. It is rarely stratified, but is so in Unst. Masses of it occur in the Scottish Isles in gneiss, clay-slate, hornblende rock, limestone, and sparingly in mica slate. A species of conglomerate composed of serpentine and limestone, forms the Verd antique^ but its locality is un- known ; a similar rock is found in Anglesea. 22. Diallage rock. Diallage rock is either simple, when it consists of diallage only, which is rare ; or compound, when it consists of dial- lage and felspar, the aspect is then granular and crystal- line ; occasionally it contains also talc, actynolite, chlorite, quartz, or mica; wjien massive it is very tough, but is sometimes fissile, owing to a parallelism in the crystals of diallage ; the colours of this latter substance are grey, green of various Hues, brown, or blackish brown. It is a stratified rock, though often obscurely so, and is described as occurring also in the primary class. It occurs with Clay-state. 153 gneiss, mica-slate, chlorite-slate, clay-slate, and serpentine, alternates with these rocks, and sometimes passes into talcose or chlorite-slate by the prevailing intermixture of talc or chlorite, It is included in the Euphotide of the French. It is the Gabbro of Italian geologists, the Schil- lerfels of the Germans. It abounds in the islands of Unst, Balta, and Fetlar, and occurs sparingly in the northern extremities of the main- land of Shetland, in Ayrshire, and in the serpentine district of Cornwall. Gabbro is abundant in Germany, Corsica, in the Alps, and in Mont Rosa is connected with mica- slate and serpentine. Euphotide Fr. This rock is described as consisting of a base of jade, or of common or compact felspar (petrosilex), containing crystals of augite. 23. Clay-slate. Clay-slate often appears as a simple rock : its schistose texture allows of its division into thin laminae, which gene- rally have a shining surface, sometimes a more or less silky aspect, but the cross-fracture is dull, fine grained, or in degree earthy, and often possesses the aspect of plates of chlorite, of which the larger planes are disposed with suf- ficient regularity to impart fissility ; sometimes however this slate has a soapy or greasy feel, arising perhaps from an intermixture of talcose matter. Its colours are, grey, bluish, bluish-black, greenish grey, and reddish brown : the black varieties include a considerable proportion of carbon (Black chalk). The strata of clay-slate are less subject to contortions than those of greywacke-slate, which however often so completely resembles clay-slate, that it is impossible to distinguish them from each other. Dr. Mac Culloch includes both in the term Argillaceous schistus, observing, that all the varieties of these rocks occur as parts of one series. Daubuisson also includes both in the term Phyllade. It is the Schtste argilleux of French writers, the Thons chief er of the Germans. It naturally divides into 1 54 Rocks Submedial Order. portions having a rhomboidal form, but without absolute regularity. It contains no organic remains. Clay-slate is found passing into mica-slate, as chlorite passes into mica ; this transition has been observed in Nor- way and the Pyrenees ; the strata of both are mostly highly inclined : it sometimes includes chlorite-slate, lydian stone, whet-slate, and quartz, hornblende and chiastolite. The slates (Killa s) of Cornwall, which are generally un- derstood to be clay-slate, are celebrated for their abundance of mineral veins, and for dykes of porphyry (Elvan of Cornwall) ; and it is somewhat remarkable that no mineral veins or dykes of porphyry have yet been observed in that county in any decided greywacke, which however is not wanting : clay-slate is also rich in metals in other countries. The Calschiste of the French consists of clay-slate, in which limestone is disseminated in patches, small veins, or laminae, either parallel or traversing the slate ; the whole possessing a slaty texture : it is cited as occurring in the Pyrenees and other moun- tain tracts. Alum-slate is a slaty rock belonging either to clay-slate or greywacke : it is impregnated with carbon and sulphur, and it is probable that the latter is in com- bination with iron, as a pyrites. When exposed to the air, the sulphur passes into the state of sul- phuric acid, which combining with the alumine, forms a sulphate of alumine, and the production of alum is completed by the action of fire. It is abun- dant in Sweden and Norway. By the French it is termed Schiste alumineux^ Ampelite alumineux^ by the Germans Alauns chief er. Whet-slate (Schiste coticule ; Schiste a aiguiser) also appears to belong equally to clay-slate or greywacke slate, but is harder and more compact, probably from the intimate mixture of alumine and silex, yet though used for the setting the edge of steel instru- ments, it yields easily to the knife. That for setting Chlorite Slate. J55 pen-knives, which is of a greenish tint, is found abundantly in the greywacke slates of Charnwood forest; that used for razors, which is a pale yel- low, is found at Namur, in layers, in connexion with a black slate which is much softer. That used for lancets is a greenish grey, and is from Germany. Flinty slate. This rock, though occurring in beds in clay-slate, into which it imperceptibly passes, is also found in greywacke-slates and in trap rocks ; it is generally very hard and compact, owing pro- bably to the presence of silex, and often consider- ably resembles flint, sometimes jasper ; in colour it varies from nearly white, through grey (touch-stone) and green, to black (lydian stone) ; and is some- times striped. It is the Siliceous schist of Mac Culloch ; the Schiste silicieux, Jaspe schistoide and Phtanite of the French ; Kies els chief er of the Ger- mans. In thin pieces it may be observed by trans- mitted light to include specks of green chlorite, 24. Chlorite slate. This rock is sometimes simple, since it consists only of chlorite, of which the grains have in some degree a regular direction, imparting a slaty texture to it ; but it som-etimes includes quartz or felspar, occasionally both; also actyno- lite, tourmaline, and pyrites ; its colours are greyish green and pale grey ; it is less rough to the touch than mica slate; its characters however are not always perfectly definite : it seems to possess a close affinity to clay-slate, into which it passes, and in which it is found in beds. It is also said to pass into hornblende slate, gneiss, and mica slate, and to alternate with them. It is the Chlorite schist of Mac 'Culloch; Chlorite schiste ; Schiste chloriteux of the French ; Chlorite chief er of the Germans. It is not a very abundant rock, and does not constitute large tracts of country : it abounds in some of the Western Isles, and alternates with clay-slate in an extensive tract u 2 156 Rocks Submedial Order. in Scotland. Humboldt observed it in gneiss in South America. 25. Talcose slate. This rock is found in the simple state, consisting of talc alone, and is then either granular or schistose ; sometimes quartz is intermixed, occasionally felspar or mica; when simple it is described as passing into serpentine, and when it includes quartz into mica-slate. The minerals found imbedded in it are diallage, automalite, chromate of iron, staurolite, and when included in gneiss, actynolite and kyanite. It was first introduced into the series of rocks by Dr. Mac Culloch. It is the Schiste talqueux of French writers, Talkschiefer of the Germans. It is not common, and is found only to a very limited extent, and then generally in beds in the older rocks, as in gneiss and mica-slate, &c. It has been observed by Dr. Mac Culloch in the Western Isles, and by Humboldt in South America, in some parts of the Great Alps between Mont Rosa and Mont Blanc, the prevailing rock is described by D'Aubuisson as being a talcose-slate, passing at inter- vals into mica-slate ; the same transition takes place in Auvergne in France, where the talcose-slate is unctuous to the touch, and as slippery as if it had been rubbed with soap. 26. Steaschiste. This rock is described as consisting of a talcose base, containing disseminated mica, or other minerals, and as possessing a slaty texture, occasionally as including a con- siderable portion of steatite, when it is very unctuous to the touch and soft, as is also the case when it contains chlorite : it is also found containing diallage, nodules of quartz and felspar, laminae of petrosilex, and talc and clay- slate ; in the latter case it is very schistose. Its name was given to it by French geologists, and it occurs in various parts of France, at Pesey in the depart- ment of Mont Blanc, &c. and in Corsica. In this country no rock has specifically been distinguished by the name of Inferior Order. 157 steaschiste, but some varieties of those occurring among the (greywacke ?) slates of Snowdon in North Wales, have a considerable affinity to it. INFERIOR ORDER. It has been stated that, as the rocks accurately belonging to the Submedial and Inferior Orders have not yet been separated, we may not be precise in prescribing the pro- per limit to each. Those which follow are now placed in the inferior, as being the lowest of the series ; some of them nevertheless contain occasional beds of various rocks ranked in the submedial order, and it is certain that in some instances, beds of the following rocks have occasion- ally been found in some, whose general geological position is above them. The following and several of those imme- diately preceding them, are frequently classed together under the general term Primitive Rocks, Terrains Primor- diaux ou primitifs^ of the French ; Ubergangsgebirge and Urgebirge of the Germans. 27. Hornblende Rock. Hornblende rock differs from the greenstone already described, in geological position more than in respect of composition. Greenstone is found in or connected with transition rocks containing organic remains 5 hornblende rock is associated only with those which are lower in the series, and do not contain them. Both consist either of hornblende alone, or of hornblende and felspar, either com- mon or compact ; the texture is always granular and crys- talline ; the hornblende is always dark green approaching to black, and the felspar commonly grey, rarely reddish. When the rock consists of hornblende only, the crystals of that substance intersect each other, imparting a granular appearance to it, or they lie with the larger planes in one direction rendering the rock schistose (Hornblende slate) , and all the varieties of this rock occur either compact or 158 Rocks Inferior Order. schistose, namely such as in addition to hornblende contain felspar, quartz, mica, chlorite, or actynolite. All the varieties of greenstone and hornblende rock are included by Dr. Mac Culloch under the term Hornblende schist. D'Aubuisson includes hornblende rock and rocks of the same character belonging to trap, under the term Amphi- bollte. It is the Hornblendgestein of the Germans ; the Primitive Trap of the Wernerian school. It passes into chlorite-slate, clay-slate, and mica-slate, and alternates with chlorite-slate and is interstratified with gneiss. It rarely forms extensive tracts, but constitutes Ben Lair in Ross-shire. Humboldt observes that it con- tains very ancient argentiferous veins. The rocks included under the term Actynolite schist differ from the preceding chiefly in this, that the crystals of actynolite (which is only a variety of hornblende) are in this rock interlaced or cross each other in various direc- tions, those of actynolite being long and slender^ while, those of hornblende are flat and tabular. 28. Primary Sandstone. Primary sandstone consists of quartz alone, or of quartz and felspar, the latter being mostly crystalline. It re- sembles quartz rock in many particulars. It is sometimes fine and granular, sometimes so fine as to have a splintery fracture, but occasionally the grains simply adhere, or are united by a cement of crystalline quartz : sometimes it is compact, and then resembles quartz rock : sometimes is gravelly and coarse, and then passes into a conglomerate, the included fragments being of quartz and felspar, either angular or rounded ; detached fragments of gneiss and clay-slate occur in the finer varieties, and when the frag-, ments abound, it passes into a rock resembling grey wacke ; when intimately mixed with felspar, it appears to pass into compact felspar. The colours are, red of various shades, pale grey, lead blue, black, brown, and white, the colours being sometimes intermixed. It has only been described Primary Limestone. 159 by Dr. Mac Culloch, and under the name of Red Primary sandstone. The garnet is the only mineral found in it. It alternates with, and passes into gneiss, and alterna- ting with it and quartz rock, it occupies very extensive tracts in the north-west of Scotland, forming some of the highest mountains of that part of the country, in strata many yards thick, and is generally subject to flexure and contortion. 29. Primary Limestone. Limestone when pure, consists of lime and carbonic acid only, but this in common with all others is variously coloured by accidental ingredients, as bitumen, oxide of iron, &c. arid which of course often modify the texture and colour. Its colours are white,, or yellowish, greyish, or reddish white. Primary limestone is crystalline, con- sisting of an aggregation of an infinite number -of small crystals intersecting each other in every direction, it is then massive, and has a more or less splintery or conclioi- dal fracture ; but when these crystals have their broad surfaces in the same direction, the rock becomes schistose, and separates in nearly parallel planes either straight or curved ; when the limestone contains mica, the same effect is generally produced. Besides mica, it often contains hornblende and other minerals, and it is remarked by Dr. Mac Culloch that those which contain these intermixed w ith the rock, may with safety be referred to the primary class : these occasional minerals are numerous, namely, mica, clay-slate in laminae, augite, talc, noble serpentine, garnet, quartz, felspar, bitumen, tremolite, sahlite, horn- blende, &c. and it often contains veins of white calcareous spar. In one instance a bed of limestone underlying a primitive rock has been described by the author just quoted, as containing organic remains, namely a limestone containing gryphites underlying a bed of gneiss in one of the Hebrides. It is often contorted like the beds of rock it accompanies. Calcaire grenu, Calcaire primitif, French, Urkalkstein German. 160 Rocks Inferior Order. It alternates with most of the primary rocks, as with gneiss in beds and nodules in Scotland, Sweden, and South America, &c. with mica-slate, in the Caraccas. Sometimes also with clay-slate. In Scotland it reposes on granite, and is then, according to Dr. Mac Culloch, often indurated and sometimes converted into a sort of cherty substance. It is said to occur in granite in the Pyrenees. It bears but a small proportion to some others of the primary rocks. In the Pyrenees, Charpentier observed imbedded in this limestone beds of breccia^ composed of fragments of its own substance cemented by calcareous matter. Cipolin. The Cipolin of French authors is a primary limestone containing mica. Ophicalce. This designation has been given to primary limestone containing serpentine, talc, or chlorite. Caldphyre^ is a primary limestone containing felspar, garnet or hornblende. Dolomite. Dolomite is (as a rock) a primary limestone, containing a proportion of magnesia, and opcurs in masses, beds, or veins, in primary rocks, and con- tains occasionally ores of arsenic, iron, and grey copper, also grammatite and mica; it occurs in Mont St. Gothard, in the Simplon, and in Siberia. 30. Mica-slate. Micaceous Schist. Mica-slate is essentially composed of quartz and mica, the plates or crystals of the latter lying flat upon the quartz, whence this rock possesses a slaty texture : it is readily distinguished from gneiss by the absence of felspar ; where the mica does not abound it may be broken across the cleavage, so as to shew little else than the quartz, and where the latter is nearly or quite wanting, the mica may often be split into laminae so thin, as to be fit for economi- cal purposes ; but hornblende, chlorite, and talc, some- times occur in it so abundantly, as to modify its character; rarely carbonate of lime ; but garnets are often so plentiful, as almost to merit description as an essential ingredient of Mica-slate Micaceous-s late. 161 the rock; occasionally it becomes porphyritic iu contain- ing large crystals of mica. The quartz is always white, while the mica varies from white, through shades of grey to black, but is rarely green. When it contains felspar it passes into gneiss ; or chlorite, or talc, into chlorite or tal- cose slate. It is regularly stratified, but is subject to great contortions. It occurs in thin beds in gneiss and quartz rock, and in- eludes beds of primary limestone : at Kieseldorf in Silesia, it is said to include a bed of basalt : it alternates with mica slate and clay slate. According to Dr. Mac Culloch, a conglomerate^ consist- ing of fragments of granite, limestone, quartz, and gneiss, imbedded in mica-slate, occurs in Scotland near granite ; and when mica-slate or gneiss approximates granite, it often contains fragments, in such a manner, as to put on the appearance of a conglomerate. As a primary rock it is perhaps the most extensive of the whole series ; it is abundant in the Alps, in Germany and France, and in the Pyrenees ; it is seen also in North and South America : Schihallien and other mountains in Scot- land are composed of it, but in England it scarcely ap- pears. The Hyalomide of the French, Gricsen Germ, consists of schistose quartz and mica, and is therefore probably only a variety of mica slate. 31. Compact Felspar. This rock differs essentially from ordinary felspar; it possesses no regular structure and contains, according to Dr. Mac Culloch, both potash and soda wheresoever found. It occurs only massive, and is either compact, with a smooth fracture or slightly granular, and is sometimes porphyritic from enclosing particles of hornblende or of quartz, and is occasionally schistose. Its colours are, white, various shades of grey, red-brown, green of different shades, or yellowish. It occurs in masses, which are often flattish, or in laminae, or imperfect beds in gneiss, into which it sometimes gra- x 162 Rocks -Inferior Order. dilates ; rarely in granite : Dr. Mac Culloch observes that it may be recognised at a distance by the white and nearly pulverulent surface acquired by exposure, and that it is found also among trap or overlying rocks. It appears to be the Petrosilex of the French, but is often confounded with Hornstone y which is a variety of compact or slightly granular quartz. Compact felspar is fusible ; hornstone is infusible ; compact felspar is occasionally the basis of cer- tain rocks which have been termed Hornstone Porphyries. White-stone ( Weiss-stein of Werner) appears to have a close analogy to compact felspar, or to be a variety of it : compact felspar is the base, and includes a little mica ; but when the mica is abundant, it lies in the compact felspar, BO as to resemble mica-slate. It has been found only in Saxony and Moravia. Eurite, Fr. The base of this rock is petrosilex (com- pact felspar), and the imbedded minerals are mica, felspar, garnet or hornblende; it is therefore a porphyritic rock. Leptenite of the French, Hornfels of the Germans, con- sists of granular felspar containing mica and quartz ; the structure of the rock being granular. 32. Gneiss. Gneiss is essentially composed of mica and felspar ; the latter being generally crystalline; but Dr. Mac Culloch observes that the felspar of a gneiss forming extensive tracts of country on the north-west coast of Scotland is compact : the prevailing constituents of gneiss are quartz, felspar, mica, and hornblende, which generally appear to alternate ; when the mica is talcose, the rock may be termed talcose gneiss; or when it contains large crystals of felspar dis- seminated, Porphyritic gneiss ; when very granular and containing the four minerals above mentioned, it has by some authors been termed Granite gneiss ; and when the ingredients are disposed in laminae, the rock becomes schistose. Gneiss occasionally contains a variety of mine- rals, as epidote, actynolite ? oxidulous iron, molybdena Granite. 163 and garnet. Gneis French, Gneuss German. It often passes into granite, the junction of the two rocks being undistinguishable ; often into mica-slate, talcose slate, quartz rock, primary sandstone and chlorite slate; and alternates with quartz rock, mica-slate, and hornblende rock, less frequently with clay-slate ; and contains beds of chlorite slate and primary limestone. A conglomerate consisting of fragments of gneiss of various sizes, united by agglutination, is occasionally found attached to gneiss, and according to Dr. Mac Culloch, is often the first or lowest bed of the primary sandstone where that lies on gneiss; it is therefore primary, and occurs on the west coast of Scotland. Gneiss, as a mountain rock, is of great extent, is always stratified, and is abundant in the mountainous regions of some parts of the European continent and in South Ame- rica ; it is scarcely found in England, but is plentiful in Scotland. According to Jameson, there are few metals which do not occur in it : the Saxon, Bohemian and Salz- burgian mines are situated in it, and yield the ores of tin, lead, copper, cobalt and silver, but in South America the veins in this rock are not productive : they yield small quantities of gold, silver, copper and galena in some dis- tricts. 33. Granite. Granite is commonly considered to be essentially com- posed of quartz, felspar, and mica, irregularly intermixed. Dr. Mac Culloch considers it to be essentially composed of two or more of the following minerals, quartz, felspar, mica and hornblende, not excluding other substances ; but al- most every specimen of granite I have examined from various countries, contains cleavelandite as well as felspar: it occasionally includes actynolite, chlorite, talc, compact felspar, and steatite : when the mass is small grained and includes large crystals of felspar, it becomes porphyritic : and when it consists of quartz, (common) felspar and horn- blende, it is the sienite of some writers : when composed of nearly parallel, but regular and alternate layers of quartz 1 64 Rocks Inferior Order. and felspar, it is termed Graphic granite (Pegmatite). A variety, consisting of felspar, quartz, and steatite, talc, or chlorite, has been termed by Jurine Protogine^ but it sometimes contains cleavelandite, -which now and then re- places the felspar. Granite occasionally includes garnet, 2ircon, fluor, spodumene, corundum, beryl, topaz, apatite, zircon, pinite, andalusite, tourmaline, pyrites, oxidulous iron, molybdena, oxide of tin. Granite is not considered to be a stratified rock, but is sometimes found apparently disposed in beds, which possess the ordinary characters of stratification. Dr. Mac Culloch observes that Conglomerates consisting of fragments of granite with mica-slate or gneiss, and granite uniting fragments of the same rocks, occur in Scot- land near granite ; and that where mica-slate or gneiss approximate [in character^] to granite, the latter often con- tains fragments of those rocks in such abundance as to put on the appearance of a conglomerate. Granite includes beds of serpentine in Aberdeenshire ; of primary hornblende rock in Bohemia : it often graduates into gneiss, and according to Mac Culloch is found in con- nexion with all the other primary rocks, into which a gra- dation of character is to be seen at the place of junction. It does not abound so greatly in metalliferous veins as some other rocks, yet there are few metals that are not occasionally found in it : but in Cornwall it abounds in veins containing the ores of copper and tin. As a mountain rock, granite is abundant in most Euro- pean countries ; nor is it wanting in Asia, Africa, and North America; and in South America, it is said by Humboldt that a granitic chain extends 250 leagues, sepa- rated here and there by little plains, from the mouths of the Guaviare and Meta, to the sources of the Orinoko. Granite veins. In several places in Britain and other countries, veins have been observed included in some of the rocks which rest immediately upon granite, and which in many instances, though not Overlying Rocks. 165 in all, consist of an intermixture of the several minerals constituting granite. In some instances these veins are extremely small, and intersect each other in various directions ; in others, they are larger, and traverse the rocks almost vertically, and often seem to proceed from the mass of granite be- neath, and sometimes are seen to be connected with it, and to proceed from it ; as though the granite itself, from which these veins arise, were of a for- mation posterior to the rocks reposing on it. And there are some, who entertain this opinion founded on the examination of these veins. TRAP ROCKS : OVERLYING ROCKS. The Trap rocks are not stratified, and are generally of posterior formation to the primary or secondary. Many, if not most of them, have been observed passing into each other; they are abundant, though commonly they are of a more limited extent than the stratified rocks : yet they sometimes rise into high mountains, or like granite, are often disposed in large masses, and are frequently found in veins. Dr. Mac Culloch observes that all rocks containing augite or hypersthene as ingredients, may safely be referred to trap rocks, and many of those containing compact fel- spar; and Humboldt says that in Teneriffe, Mexico, and in the Cordilleras of Quito, the rocks of the trap formation remain distant from the modern currents of lava : every thing, he observes, announces that these two classes of substances, although they owe their origin to analogous phenomena, ^namely, volcanic action,] are nevertheless of very different Primitive limestone, p. 159 a cerites Plastic c lay, p. 134 Cornean a rock allied to Wacke ? p. 171 Calschiste Clay-slate enclosing limestone p. 154 Calciphyre Limestone (primitive) containing crys- tals of different minerals, felspar, &c. p. 160 Ceritenkalkstein Lower marine formation, p. 132 Chlorit schiefer Chlorite slate, p. 155 Chlorite schiste Chlorite slate, p. 155 Cipolin Limestone (primitive) containing mica, p. 160 Craie blanche ou superiure. . Upper chalk, p. 134 tufau Lower chalk, p. 134 inferieure Grey chalk and Chalk marie, p. 135 chloritee Green sand Dolerite Compact felspar and augite, &c. p. 170 Dolomite Dolomite, p. 160 Domite Harsh claystone enclosing mica, p. 166 Deuxieme terrain marin .... Upper marine formation, p. 131 d'eau douce Lower freshwater formation, p. 132 Diabase Greenstone, p. 151, 172 schisto'ide Greenstone slate porphyroide Porphyritic greenstone, p. 172 1 82 Rocks Table of Synonymes. Dichter Felspath Compact felspar, p. 167 Diorite Greenstone, p. 151 Eurite '. Var. of Whitestone, p. 162 Euphotide Diallage rock, p. 153 Felspath compacte Compact, felspar, p. 167 Flotsgebirge Beds between Chalk and Coal, p. 134 Gabbro Diallage rock, p. 153 Glauconie craieuse Green sand, p. 136 Glimmerschiefer Mica-slate, p. 160 Grauwacke Greywacke, p. 148 Grauwackenschiefer Greywacke slate, p. 148 Gres, sables verts & ferrug.. . Green and Iron sands, p. 136 bigarre New Red sandstone, p. 140 rouge New Red conglomerate, p. 140 des Houilleres Coal grit, or Sandstone, p. 143 Gres ancien Old red sandsone, p. 146 Griesen Quartz and mica (schistose), p. 161 Grunstein Greenstone, p. 151 Gneis, Gneuss Gneiss, p. 163 Granit . Granite, p. 163 Grunsteinschiefer Greenstone slate Hemithrene Hornblende and limestone, p. 150 Hornfels Var. of Whitestone, p. 162 Hornblendegestein ....!.... Hornblende rock, p. 158 Hyalomicte Quartz and mica (schistose), p. 161 Jaspe schistoide Flinty-slate, p. 155 Jurakalk formation Oolite formation, p. 138 Keratite Hornstone porphyry, p. 167 Kieselschiefer Flinty slate, p. 155 Klingstein Clinkstone, p. 167 porphyr Clinkstone porphyry Knockenfurendergyps, &c. . . Lower freshwater formation, p. 132 Kohlensandstein Coal grit, or Sandstone, p. 143 Kreide formation Chalk formation, p. 134 Lave Lava, p. 174 Leucostine compacte Clinkstone, p. 167 Leptenite Var. of Whitestone, p. 162 Macigno Beds belonging to thePlastic clay, p. 134 Molasse Plastic clay, p. 134 Melaphyre Petrosiliceous hornblende, containing crystals of felspar, p. 168 Mandelstein Toadstone, p. 171 Micaschiste Mica slate, p. 160 Mimophyre Variety of grey wacke, p. 148 Mimose Lamellar felspar and augite, p. 170 Muschelkalk Lias (of Germany ?), p. 139 Nagelfluhe Plastic clay, p. 134 Ophicalce Limestone (primitive) containing ser- pentine, talc, or chlorite, p. 160 Ophite Hornblende petrosilex imbedding crys- tals of felspar, p. 167 Ophiolite Serpentine, p. 151 Obsidienne Obsidian, p. 174 Petrosilex Compact felspar, p. 162 and p. 167 Pegmatite Graphic granite, p. 164 Perlite (Perlstein) Pearlstone, p. 174 Pechstein Pitchstone, p. 168 Pechstein porphyr Pitchstone porphyry, p. 168 French^ German and English. 183 Phvllade . . . $P a * Clayslate p, 153 ^part Greywacke, p. 148 Phyllade intermediaire Greywacke slate, p. 148 Phonolite Clinkstone, p. 1 67 Phonolite porphyroide Clinkstone porphyry, p. 167 Phtanite Flinty slate, p. 155 Piperino Hard Volcanic tufa, p. 176 Plastischer thon Plastic clay, p. 132 Porphyr gebirge New Red porphyry, p. 141 terreux Clay porphyry, p. 166 euritique Felspar porphyry, p. 167 secondaire J _ T , de gres rouge New Red porphyry, p. 141 schiefer Clinkstone porphyry, p. 167 Porphyr retinitique Pitchstone porphyry, p. 168 Ponce Pumice, p. 175 Poudingue New Red porphyry, p. 141 Protogine Protogine granite, p. 164 Premier terrain marin Lower marine formation (London clay), p. 132 d'eau douce.. Plastic clay, p. 132 Quadersandsteiri a sandstone lying (in Germany) below the oolites, p. 139 Psammite micace Coal grit, p. 143 rougeatre New Red conglomerate, p. 141 Quarzstein Quartz rock, p. 151 Quartzite ditto, p. 151 Quartz en Roche ditto, p. 151 Rauchwacke Hard cellular magnesian limestone? p. 142 Retinite Pitchstone, p. 168 Roche de quarz Quartz rock, p. 151 aggreges Aggregated rocks de cement Cemented rocks trappeens Trap rocks secondaires Secondary rocks de transition Transition rocks Rothe todte liegende New Red conglomerate, p. 141 Saaswater formation Freshwater formation, p. 130 Schieferthon Slate clay (of Coal measures), p. 143 Schillerfels Diallage rock, p. 153 Schiste traumatique Greywacke slate, p. 148 micace Mica slate, p. 160 alumineux Alum slate, p. 154 coticule . ) novaculite. > Whet slate, p. 154 aiguiser . ) silicieux Flinty slate, p. 155 argilleux Clay slate, p. 153 chloriteux Chlorite slate, p. 155 talqueux Talcose slate, p. 156 Schiste de transition Grey wacke slate, p. 148 Serpentin Serpentine, p. 151 Steaschiste Steaschiste, p. 156 Stigmite Pitchstone porphyry, p. 168 Stemkohlengebirge Coal measures, p. 143 Talkschiefev Talcose slate, p. 156 184 Rocks Table of Synonymes. Terrain de sediment superieur Beds above the chalk, p. 130 tertaire Beds above the chalk, p. 130 secondaire Beds between chalk and coal, p. 154 houiller Coal measures, p. 143 de transport Diluvium, p. 177 primordiaux Primitive rocks, p. 157 Terrain marin Deposits by salt water, p. 130 Tephrine Grey, porous hard lava Thonporphyr Clay porphyry, p. 166 Thonschiefer Clay slate, p. P53 Thonstein porphyr Claystone porphyry, p. 166 Thonstein Claystone, p, 166 Traumate Grey wacke, p. 148 Trachyte a fusible petrosiliceous (felspathic ?) paste, with crystals of vitreous felspar, p. 168 Trapporphyr Pitchstone porphyry, p. 168 Trappite a hard variety of Cornean trap, enclosing mica, &c. p. 172 Trass a pumiceous conglomerate, p. 175 Troisithne terrain d'eau douce Upper Freshwater formation, p. 131 Travertine a calcareous building stone of Rome, p. 176 Tuf volcanique Volcanic tufa, p. 176 Urkalkstein Primitive limestone, p. 159 Ubergangkalkstein Transition limestone, p. Ubergangsgebirge&urgebirge Primitive and Transition rocks, p. 1ST Variolit Toadstone, p. 171 Vakite Base of wacke. containing mica. &c. p. 172 Vulcanisches tuf Volcanic tufa, p. 176 Vulcanischen breccia Volcanic conglomerate, p. 175 Wacke Wacke, p. 166 Weiss-stein White-stone, p. 162 Wetzchiefer Whet slate Zechstein Magnesian limestone, p. 142 LECTURE VII. Of Mineral Veins Of Mining as practised in Cornwall Processes employed in reducing the Metallic Ores Of Salt Deposites Of the Deluge Of the Excavation of Vallies Of Volcanoes Of the Internal Structure of the Earth Concluding Observations. OF MINERAL VEINS. IN treating of veins, we have a two-fold object. Thej merit our attention in respect to the extraordinary cir- cumstances which attend them in all countries in which they occur ; and also on account of their being the chief mineral deposits. But mineral deposits are of two kinds : for metallife- rous ores are largely found in beds, as well as in veins. Mineral beds are for the most part horizontal ; and are found both in primitive and secondary countries, of various elevation. The ores of copper, iron, and lead, occasionally occur together in beds in primitive mountains ; and sometimes gold and silver are intermixed with them. Cobalt, and certain ores of mercury, also occur in beds. Almost all the metalliferous ores in the great mining district of Swe- den, are in beds in primitive mountains. Lead, zinc, and iron ores occur abundantly in beds in secondary mountains. In England, some ores are found in beds ; but by far the greatest mineral deposits of this country are in veins : it is uniformly the case in Cornwall. A vein may be described as ajissure that has been after- wards filled up with several different substances. Humboldt observed a vein of calcareous spar 140 feet wide, traversing gneiss in the Alps of Switzerland. Jameson 186 Oj* Mineral Veins. observed a vein of porphyry-slate traversing sandstone in the Isle of Arran, nearly 160 feet wide ; and in Scot- land, veins of pitchstone and greenstone, from 10 to 100 feet wide. But these veins do not appear to have been what may be termed metalliferous veins j which for the most part, are much narrower \ but the vein of brown iron stone mingled with silver, traversed by small veins of a softer substance, and much richer, and in which are situ- ated the silver mines of Pasco in Peru, is 1300 yards wide. It is said that in most primitive metalliferous mountains, veins extend but a few hundred fathoms in length, and that their width does not exceed two feet. Is has also been said, that a description of the veins of Cornwall would, generally speaking, suffice for those of al- most every other country ; and having heretofore given much attention to their actual state, I shall confine myself chiefly to them, and endeavour to give a general outline of their direction, length, depth, width, dip and contents. But in these respects, veins have not such an uniformity, as that the history of one would be an history of the rest : almost every vein has something peculiar in it j something to interest the geologist. The metalliferous veins of Cornwall, namely, the veins producing copper and tin, which are the chief mineral pro- ductions of the county, run in the direction of nearly east and west ; they may vary a few points. There are how- ever other veins, that occasionally contain lead and silver, but more often are devoid of any metallic substance, which for the most part run north and south. These facts are extremely curious. , Metalliferous veins may sometimes be traced along the surface of the earth, by a certain ochreous or rusty appear- ance ; but this is not very common. A vein may be said in some sort to resemble a deep cleft or crack in the field. This 'cleft, whatever might be its depth, must of course have a direction under ground : either it would be quite straight down, or it would have a slanting direction beneath the surface. Of Mineral Veins. 187 The veins of Cornwall scarcely ever take a direction quite straight down, or in other words, quite at a right angle with the horizon ; but almost always dip, or incline away from that angle. So that the metalliferous veins which run east and west, dip or underlie either towards the north or south ; and the non-metalliferous veins, which run north and south, dip either towards the east or west. In this respect, there is no general uniformity ; some are nearly perpendicular ; others are very oblique. In the small space of one little hill, in- stances may be found in which veins of almost every des- cription, dip or underlie in almost every direction, travers- ing each other in such manner as to set at defiance all the former experience of the miner. The length of no one vein in Cornwall has as yet been satisfactorily proved. Some of them have been traced two, or three, or even four miles : but no instance has occurred in which a vien has been known to stop. Nor has the miner ever yet seen the bottom of a vein. The length and depth to which veins extend, therefore, are not known. There are several mines in Cornwall upwards of 1000 feet in depth from the surface, and two or three nearly, if not quite 1500 feet deep. Metalliferous veins differ exceedingly in regard to their width. A vein containing tin ore, in a mine called Whcakn Coates, was only three inches wide, but was so rich as to be worth working ; while another, in a mine called Relis- tian, was upwards of 30 feet wide, and was also rich in tin. Some of the veins containing copper in Herland mine, did not exceed 6 inches in width ; and so continued for a few fathoms, but eventually passed away east and west in mere strings, scarcely thicker than paper ; but these veins yielded copper of a very rich quality. A copper vein in the next hill, varied from 12 to 24 feet in width, and was also very productive of copper. But the generality of metallferous veins, both of tin and Copper, are from one to three feet in width : and these are preferred by the miner, because the ore they contain is 2 A 2 188 Of Mineral Veins. generally less intermixed with other substances, than that of wider veins. Hitherto we have been speaking principally of metalli- ferous veins. There is yet one circumstance, and a very important one, in regard to these, that we must not fail to notice. These veins are not Jilted with metalliferous ores. The ores both of copper and tin principally occur in quan- tities which, though they may extend many fathoms every way, generally occupy, in point of fact, but a small com- parative portion of the vein, and are therefore properly enough termed bunches, A question here naturally arises. With what substances are the remaining parts of the veins filled up ? These are occupied sometimes by rocks, or by stony or earthy sub- stances of various descriptions ; or by rubble, or refuse matter that seems to have resulted from the ruin of some part of the neighbouring country. The non-metalliferous parts of a vein, of whatsoever composed, are commonly termed by the miner deads y because they yield him nothing. Sometimes, however, veins are found to have large empty spaces ; but this, in Cornwall, is not common. Water is very abundant in veins, particularly in those rich in tin or copper. On a large mine it is not unusual to see two or three steam engines, for the purpose of drawing the water. These may raise and discharge into the neighbouring valley, at least 1000 gallons of water every minute, night and day. The sides of metalliferous veins are generally very deter- minate ; and are covered by a hard dark-coloured crust 5 called by the miner the walls of the vein : and there gene- rally runs down every vein, a small vein of a whitish clayey substarice, which sometimes adheres to one, sometimes to the other wall. The ores of copper and the ore of tin (for of tin there is but one description of ore, while there are many of copper) do not often occur together in the same vein to any great depth beneath the surface. At about 80 or 100 feet under the surface, the first traces ,of copper or tin are usually found ; rarely nearer to it than Of Mineral Veins. 189 feet. But when at last they are found, it is not to be understood that these ores consist of one close and compact mass : on the contrary, they are generally mingled with other substances, such as lead ore, iron pyrites, and the ore of zinc, accompanied by fluor spar, quartz, &c. These are in some cases loose in the vein ; in others, they are hard and attached to one or to both sides of it. Sometimes the ores both of tin and copper are found thus circumstanced together in the same vein ; and when so found, it generally happens that all trace of tin is soon lost. If tin be first discovered, even without a trace of copper, it is not unusual, that in the course of sinking 80 or 100 feet more, all trace of it is lost, and copper only is found. The vein of course was at first called a tin vein ; but after- wards became only a copper vein : and many of the most productive mines in Cornwall have been exactly so circum- stanced. Nevertheless, in some veins, tin continues to be found to the great depth of nearly 1000 feet beneath the surface, almost without a trace of copper. But if, instead of tin, copper be first discovered at the depth of 80 or 100 feet, it seldom or ever happens that tin is found below it in the same vein. In one or two of the deepest mines in the county, both -copper and tin have continued down together, in the same vein, to the greatest depth at which it has been seen by the miner; sometimes one prevailing, sometimes the other: particularly in the mine called Cook's Kitchen. It has been stated that the tin and copper veins run nearly east and west ; but that the veins which run nearly north and south^ scarcely ever contain a trace of tin or copper: in some few instances, they have been found to contain the ores of silver, lead, cobalt, and iron : others have produced antimony. These north and south veins are usually filled by quartz, or a whitish or bluish clayey substance, or an ochreous substance ; and sometimes by all three. When a vein of this description meets with another containing tin or cop- per, \tpasscs through the tin or copper vein, which, there. ISO Of Mineral Veins. by, seems sometimes to have been split, as it were, into numerous little branches ; the north and south vein con- tinuing its course straight forward without interruption. Not only is this curious effect produced, but also another of a much more extraordinary nature. In searching for the tin or copper vein on the other side of the north and south vein, it sometimes cannot be found for a length of time, nor without much labour and expense : forty years have been spent in such a search. The experience of the miner sometimes avails him nothing. For, instead of continuing its course, instances have been known in which the tin or copper vein has been again found 120, or even 450 feet, north or south of that part of it, on the other side of the north and south vein. North and south veins vary in w idth from one inch to ten pr twelve feet; but whatever be their width, they always divide tin or copper veins, 'and generally alter their course; or, in the language of the miner, heave them out of their course. In some parts of the mining districts of Cornwall, metal- liferous veins are so numerous, that with the miner, the question is not where a vein can be found, but where he will be most likely to meet with one productive of copper or tin. Years of labour and large sums of money are often expended in vain, because there is no circumstance by which he can determine with certainty that his efforts will be successful. There are many mines through which several veins of copper and tin take their course very near to each other. If a copper vein meets with a tin vein, it is universally the case that the copper vein passes through that of tin, and generally heaves it out of its course, greatly to the incon- venience and loss of the miner, who is often puzzled to find it again. There are still other, and if I may so say, subordinate veins found in Cornwall. The explanation of their nature and effects would trespass too greatly on your time : they rarely contain any metalliferous substance, but they occa- sion prodigious vexation and expense to the miner. Of eins. In elucidation of what has been just said of the phe- nomena attending the veins in Cornwall, I shall offer for your inspection a sketch of those which actually occur in two mines called Tin Croft aud the Pink. Let the follow- ing figure represent a North and South Section of Tin Croft Mine. The space between a and b may be considered as the surface of the mine, shewing the run of the veins upon it ; it does not however in this respect represent the fact as it occurs in nature, since these veins do not appear on the surface, which is covered by alluvial matter and grass : but it exhibits what exists beneath that -covering. All these veins above represented are found in Tin Croft mine, in less than half a mile from north to south. It may be observed that there are three veins of copper c, J, e ; three of tin, f, g) h ; and one yielding both copper and tin, i. Two of the copper and one of the tin veins run on the sur- face east and west, and are intersected by a vein running north and south which is not metalliferous; and we shall further observe that the copper and tin veins were not merely intersected, but also, that the parts of them oh the 192 Of Mineral Veins. western side of the north and south vein, were c heaved* out of their regular course towards the south. Let us remark the downward direction of the copper and tin veins ; not one of them runs straight down ; they dip or underlie more or less either towards the north or south. Two of the copper veins intersect one of the tin veins, and pass through it without altering its direction. It has been said that the miner has never seen the bottom of a vein. Three of the veins in Tin Croft seem to stop ; the fact is, that the miner did not pursue these veins to so great a depth as the others ; their direction beneath where they seem to stop is not exhibited, because it is not known. From one of the copper veins which underlies a little towards the south, two branches go off underlying much quicker towards the north : the veins of Cornwall rarely branch off in this manner. The section of the Pink mine is a remarkable instance in proof of the assertion that copper veins meeting with those of tin, always divide, and pass through, and mostly c heave 1 them. Let the following figure represent a North and South Section of the Pink mine. The space between a and b represents the surface, ex- hibiting, as in the former case, the run of the veins. Of Mineral I'eins. 193 In this mine there were four east and west, or metal- liferous veins, three being of copper, c d e ; and one of tin f. These veins were intersected by a north and south vein (visible on the surface of the sketch) that was not metalliferous ; which heaved the parts of the copper and tin veins on the western side of it, more towards the north than are those parts of them on the eastern side of it. The tin vein ran near the southern extremity of the mine, underlying in its downward direction greatly towards the north. It will be noticed that the copper veins underlie in the contrary direction, that is, towards the south. One of them, c, meeting with the tin vein in its course, interrupted it, and ' heaved 1 that part of the tin vein on the north of the point of intersection, twenty-four fathoms nearer the sur- face. It was afterwards found that the tin vein was again interrupted by another copper vein, and again heaved to- wards the surface, though only about ten fathoms : a third time it was cut through by still another copper vein which does not appear on the surface of the mine, and again heaved, though less than before, towards the surface. There are yet some important points respecting mineral veins, on which I purpose saying a few words. I mean in regard to the probable manner in which they were formed, and by what means they were filled. They who contend that the great masses of the globe are altogether what they now are, by the agency of 'fire ', assert that veins were formed by the contractions which took place in those masses while cooling, and that they were filled from below : in other words, that the contents of veins were protruded into them from the internal parts of the globe by the agency of fire. Those who, on the contrary, contend that the great masses of the globe are what they now are through the agency of water ^ assert that mineral veins were originally open fissures or rents, caused by the subsiding of the great masses of the globe ; and that these fissures were filled from 2* 1 94 Of the Methods of Mining in Cornwall. above, receiving into them the metals which formed a part of a great chaotic fluid. I am not now about to enter into an examination of the comparative merits of these two doctrines, but shall pro- bably hereafter say a few words on this part of the subject. I cannot however pass by one or two observations in regard to the relative ages of veins. It has been said that copper veins meeting in their course with those of tin, always divide and pass through them. This seems clearly to shew that tin veins are the oldest, or they could not have been so divided. It has also been said that the north and south or non- metalliferous veins, always divide the veins of copper as well as those of tin. This clearly shews that both the tin and copper veins are older than the north and south veins > or they could not have been so divided by them. But other veins, not containing any metallic substance, are occasionally found ; which, as they divide and pass through every one of the fore-mentioned, are therefore of still later formation. A more particular account of the veins of Cornwall may be found in the second volume of the Transactions of the Geological Society. SKETCH OF THE METHODS PURSUED IN THE WORKING OF MINES IN CORNWALL. Neither the Mineralogist nor the Geologist, if strictly confined to the objects of his science, is in any respect concerned in making acquaintance with the modes by which the various metalliferous ores, and their accompanying minerals, are extracted from the veins or beds in which they mostly are found. They do not often occur dissemi- nated through a rock in such proportions as to render them the objects of the miner's pursuit ; and hence as his re- search is confined to comparatively narrow limits, his science is extremely interesting in itself, when considered Of the Method* of Mining in Cornwall. 195 apart from the important degree in which his labours con- tribute to the common stock of human convenience and enjoyment: an enjoyment of which they will think he scarcely possesses an adequate share, who only know that he is labouring full one half of his waking hours in the dismal pits and passages of a mine, working by the light of a small candle, either alone, or accompanied at most by two or three others. The life of a miner, cheerless as it may seem to be, is not commonly so to him : his business is one of reflexion as well as of labour ; and the consequence is, that the uneducated Cornish miner is very far remote from the uncouth barbarian that some have supposed him to be, but is on the contrary a man of much more than common intel- ligence considering his rank in society. Mining has become greatly and generally interesting from the vast speculations that have lately taken place in the mines of America ; speculations which, it cannot reason-i ably be doubted will in some cases repay and more, the large advances they require, while on the contrary, it may with equal reason be assumed that others will terminate in disappointment and immense loss. The brief notices con- tained in the few following pages are intended only to give a partial and very general view of the manner in which) and the modes by which, the mines of our own country are wrought, leaving out much of detail, and confining the view to the Copper and Tin Mines of Cornwall, as being of more general interest, and comprehending more extensive views of mining, than the Lead Mines of the North of England. One inducement to the insertion of the present article has been, the belief that the practice of the art of mining is little or not at all understood generally ; a suspi- cion almost confirmed by the singular error fallen into by a lady of deserved eminence in the literary world. Miss Edgeworth, in her tale of Lame Jervas, assumes him to have been born in a Cornish mine, and not to have seen day-light until the age of 14 years ; and she has assumed that horses are kept beneath the surface. It is not too much to say, that no child was ever born in a Cornish 196 Of the Methods of Mining in Cornwall. mine, into which no woman ever enters but from motives of curiosity, and that no horse is ever kept or even intro- duced beneath the surface. It is important to notice even the slight errors of a writer who constantly evinces an anxiety not to mislead, whose works must be universally read and with delight, and to whom the rising generation, and indeed even their parents, are under almost infinite obligation. A few words on the American Silver mines may not be misplaced. Those of Mexico are situated in the moun- tains of that country, at very considerable elevations ; those of Peru are about three miles above the level of the sea. In Mexico there is a School of mines ; in Peru none. In Mexico the excavations are in many mires of very con- siderable depth, greater as it is said than those of any mines in England, and it is extraordinary that the Mexican miner should have been able to unwater these mines with- out steam engines, and chiefly by the labour of horses. In Peru on the contrary the mines are mere holes of very in- considerable depth, and so ignorant have they until lately been in that country of the art of mining, and of the power of machinery of any sort, that the water and ore, as well as the unprofitable refuse of the workings, have chiefly if not entirely been brought to the surface on the heads of the workmen ; even in Mexico the ore is fre- quently delivered on the surface of the mine by men, who carry on their shoulders in bags made of skins sewed to- gether, two to three cwt. at a time, walking with that weight up a flight of steps from the bottom to the surface, at an angle of about 45 degrees. It may therefore be as- sumed that the superior skill of British miners, assisted by the power of the steam engine, where wood or coal is found in sufficient abundance for fuel, will be able to ac- complish much more than could be performed by systems so rude, if system it could be called, where no regularity exists in the underground workings. In several great mining tracts in Mexico neither wood nor coal has been found, and hence some of the steam engines prepared for Of the Methods of Mining in Cornwall. 197 America, have been appropriated to the working of our mines at home. In Peru however, there is coal, and steam- engines sent from England eight or nine years ago have been working in the shallow mines of Pasco. When fuel is wanting, the miner must resort either to horse-power for raising water and ores, or to the mountain-streams, where- ever they are found, for turning the wheels and working some of the various engines which have been used in Mexico, and others known and used in European coun- tries. Where water abounds, the German engineer will be employed with most advantage, where steam-engines cm be rsed, the Cornish miner and engineer. The districts of the north of England in which lead is chiefly found is more mountainous than the mining parts of Cornwall, and the mines are mostly in elevated tracts, and not being very deep, are consequently unwatered readily by cutting, from the side, near the base of the mountain to the vein, a passage or adit, through which passage the water flows into the vallies and thence to the sea ; steam-engines are consequently but little needed, and thereby a very great expense is saved. Not so in Cornwall ; in the mining districts of that county steam-engines are seen on every hand, and some of enormous power ; water-engines on the contrary are com- paratively few. The mining tracts are of but little eleva- tion, for they rarely exceed 500 feet above the sea level. Owing to this circumstance, together with the frequency of the hills and want of breadth in the county itself, it aifords but few streams, and those of no very considerable dimension or power; the few it does afford however are often conducted by artificial courses, or Leafs,, very con- siderable distances, and perform duty at several mines be-- fore they fall into the sea. A small stream rising three or four miles from Cook's Kitchen Mine near Redruth, turns two wheels on the surface of the mine and one under- ground, the diameter of the smallest being about 40 feet, Jhe largest about 50- feet. 198 Of the Methods of Mining in Cornwall. In treating of the veins of Cornwall in a preceding page, it is said that the difficulty is not where to find a vein y but where to Jind a profitable one. A good neighbourhood ; a fine gossan (a fine gossan is a loose friable ochreous sub- stance, principally siliceous,) in the upper part of the vein or lode ; plenty of black Jack (blende), for black Jack, says the miner, rides a proud horse ; and if, at some little depth, on cutting the lode, the mine is inundated with water; these are symptoms of encouragement for the miner, even if little or no copper ore should appear near the surface. Having selected the vein he means to work, his first object is, of course, to secure the right of working it. If it be in the waste, it is the property of the King as Duke of Cornwall, and the miner consequently applies to the proper agent, or to those who, under him, have a right to grant a lease, or sett) as it is termed by the miner : if on the contrary it be in private property, the lord of the soil is applied to, or his agent; the boundary of the future mine being settled, a grant in the form of a lease or sett is obtained for 21 years, or for such part of that term as the workings shall be proceeded in ; the dues or the lord's share is decided, which varies from one-eighth to one* fifteenth, according to circumstances, of all the ores raised, the proprietor's proportion being generally sold with the ores belonging to the mine, and the tribute or dues paid to him in cash. But it is generally the case that a Company for the working of the mine is made up before the mine i& taken, the shares being divided into 64th, sometimes 128th parts. The next object is to determine what part of the vein it will be most advantageous to begin upon, which however is often decided by convenience ; the convenience of bring- ing up to it an adit t from the lowest ground within the + It is sometimes the case that an adit is driven through one mine to -to the next, thus forming a free passage for the water of each mine, which falls into it from above, as well as for- that which is lifted by tbe Of (he Methods of Mining in Cornwall. 199. sett j this being begun, the next object is to sink a shaft, the underlie of the lode being first determined, often by sinking down a short distance from the surface on its course. The shaft however is rarely continued in this direction, but is mostly perpendicular. Shaft Suppose the above to be a north and south section of a hill in which a copper lode runs east and west; the adit then is driven from near the base of the hill to the vein or lode underlying north, and through it to the shaft, which is perpendicular. The place of the shaft on the surface is determined by the underlie of the lode, from knowing which the miner decides on sinking his shaft so as to cut or traverse the lode at a particular depth beneath the surface, according to circumstances. If the miner desires to ex- plore the lode above the adit, he cuts a passage, or cross- cut (a) from the shaft, south, to the lode ; but after the lode is traversed by the shaft, the cross-cut (b) is to the north to find the lode. In both cases he will most pro- bably find a considerable quantity of water, at first, rush pumps and discharged into it. In the principal mining district of the county there is one, termed, from its being begun at the sea level in one of the branches of Falrnouth harbour, the deep arfi7, which traverse* many mines, and which, taking into account its circuitous direction, is about 30 miles in length. 202 Of the Methods of Mining in Cornwall. this is to be made of a dimension nicely adjusted to the power of the stream ; pumps, of which the pipes are of iron are then let down into the mine, and are connected with a crank on the axle of the wheel, and thus the water is in some favorable instances, exhausted and kept under. But where there is no stream of water on the surface, the only resort is a steam-engine, commonly of considerable power, for the miner now wisely considers that it is better to put an effectual power on the mine at once, than to lose time and money by erecting a small engine to try the lode. Two large steam-engines are not uncommonly employed on one mine, and there are many instances in which one engine with its apparatus and pumps, together with the expense of sinking a large shaft on which it is situated, have cost more than ^10,000. The miner does not reckon the power of his engine by the power of the horse, but by the diameter of the cylinder ; the cylinders of the largest engines in the county are 91 inches in diameter; there are two of 90 inches on the Consolidated mines. As an ex- treme instance of the prevalence of water in some mines, . it may be mentioned that from one in the western part of Cornwall not many years ago, after a long series of very wet weather, the engines were computed to draw off 1600 gallons every minute day and night during six w r eeks. The steam-engine or engines are commonly placed on shafts that are both the largest and the deepest in the mine. An ordinary shaft, that is to say, one which is only to con- tain the ladders, (for the miner always descends by the ladder, never by the rope as in coal mines) is only just large enough to answer that single purpose, but the engine shaft, as it is termed, is generally large enough to admit of division into two parts, one for the pumps and another for the bucket or kibble, and sometimes a third, as a foot-way or ladder, and the bottom of this shaft is commonly the deepest part of the mine, and is termed by the miner, the sump : in the bottom of it, to which the pumps extend from the summit, the waters of the mine collect by means Of the Methods of Mining in Cornwall. 203 of the underground workings connected with it, and the incessant drainage into it of the country , or rock, in which the mine is situated, But besides being employed in the unwatering of a mine, the steam-engine is, sometimes used for raising the ores, which it does with a rapidity far greater than can be at- tained by any other means ; sometimes however very small engines, termed steam-whims , are raised for this purpose alone in such mines as are very rich. It is then by the assistance of this extraordinary machine that man is enabled to prosecute his scarcely satiable thirst for wealth ; by it he is enabled to sink to great depths, to drive level after level, without having hitherto discovered the extent of the power of his several engines unitedly, or consequently the depth to which his researches may ex- tend. Dolcoath, situated at the northern foot of Carnbrae, a granite hill contiguous to Redruth on the west, is one of the deepest, if not the deepest mine in Cornwall, being about 250 fathoms from the surface to the sump. This mine has been working about or above 50 years, and is still rich owing to some late discoveries : its underground work- ings are so extensive that the inspecting captain is occu- pied four days, though not consecutively, in examining the workings previous to making the monthly bargains with the men. The mode of making bargains with the men, is in gene- ral terms the following. Once in each month the captains traverse the workings of the mine, to determine what parts of it are to be wrought : in some parts there is sinking to be done, in others driving laterally, where there is no ore in which case the work is done by the fathom, and this is termed tut-work : but where there is what the miner terms a course of ore ', that is where the ore is pretty continuous, the miner is not paid by the fathom, but by the value in pounds sterling of the ore he raises, and his engagement runs thus, that he is to work at a certain rate during the next month, say that he is to receive 10s in the pound sterling of the value of all the ore he raises this is termed 2 c 2 202 Of the Methods of Mining in Cornwall* this is to be made of a dimension nicely adjusted to the power of the stream ; pumps, of which the pipes are of iron are then let down into the mine, and are connected with a crank on the axle of the wheel, and thus the water is in some favorable instances, exhausted and kept under. But where there is no stream of water on the surface, the only resort is a steam-engine, commonly of considerable power, for the miner now wisely considers that it is better to put an effectual power on the mine at once, than to lose time and money by erecting a small engine to try the lode. Two large steam-engines are not uncommonly employed on one mine, and there are many instances in which one engine with its apparatus and pumps, together with the expense of sinking a large shaft on w r hich it is situated, have cost more than ,^10,000. The miner does not reckon the power of his engine by the power of the horse, but by the diameter of the cylinder ; the cylinders of the largest engines in the county are 91 inches in diameter ; there are two of 90 inches on the Consolidated mines. As an ex- treme instance of the prevalence of water in some mines, . it may be mentioned that from one in the western part of Cornwall not many years ago, after a long series of very wet weather, the engines were computed to draw off 1600 gallons every minute day and night during six weeks. The steam-engine or engines are commonly placed on shafts that are both the largest and the deepest in the mine. An ordinary shaft, that is to say, one which is only to con- tain the ladders, (for the miner always descends by the ladder, never by the rope as in coal mines) is only just large enough to answer that single purpose, but the engine shaft, as it is termed, is generally large enough to admit of division into two parts, one for the pumps and another for the bucket or kibble, and sometimes a third, as a foot-way or ladder, and the bottom of this shaft is commonly the deepest part of the mine, and is termed by the miner, the sump : in the bottom of it, to which the pumps extend from the summit, the waters of the mine collect by means Of the Methods of Mining in Cornwall 203 of the underground workings connected with it, and the incessant drainage into it of the country , or rock, in which the mine is situated, But besides being employed in the unwatering of a mine, the steam-engine is, sometimes used for raising the ores, which it does with a rapidity far greater than can be at- tained by any other means ; sometimes however very small engines, termed steam-whims^ are raised for this purpose alone in such mines as are very rich. It is then by the assistance of this extraordinary machine that man is enabled to prosecute his scarcely satiable thirst for wealth ; by it he is enabled to sink to great depths, to drive level after level, without having hitherto discovered the extent of the power of his several engines unitedly, or consequently the depth to which his researches may ex- tend. Dolcoath, situated at the northern foot of Carnbrae, a granite hill contiguous to Redruth on the west, is one of the deepest, if not the deepest mine in Cornwall, being about 250 fathoms from the surface to the sump. This mine has been working about or above 50 years, and is still rich owing to some late discoveries : its underground work- ings are so extensive that the inspecting captain is occu- pied four days, though not consecutively, in examining the workings previous to making the monthly bargains with the men. The mode of making bargains with the men, is in gene- ral terms the following. Once in each month the captains traverse the workings of the mine, to determine what parts of it are to be wrought : in some parts there is sinking to be done, in others driving laterally, where there is no ore in which case the work is done by the fathom, and this is termed tut-work : but where there is what the miner terms a course of 'ore ', that is where the ore is pretty continuous, the miner is not paid by the fathom, but by the value in pounds sterling of the ore he raises, and his engagement runs thus, that he is to work at a certain rate during the next month, say that he is to receive 10s in the pound sterling of the value of all the ore he raises this is termed 204 Of the Methods of Mining in Cornwall, tribute-work ; and in the bargain he makes, is included the finding of his own tools, and the repairing of them, together with such candles and powder as he may use, which he procures on the mine, and are duly placed to his account in the mine books ; and not only this, but his bargain also includes the drawing of his work to the surface, and the rendering of it merchantable by women and children, and if after all he gains 20s a week he considers himself to have made wages. The mine having been duly inspected by the captains, and the price at which every part of the labour ought to be per- formed being noted, the men collect on a given day in each month in front of the counting-house, of which the steps or stairs to the upper and only story are generally on the out- side, the top of the steps being terminated by a sort of covered stand. In this the principal captain takes his station with the clerk of the mine, often accompanied by the under- ground captains. A handful of small pebbles are then handed to him, and the auction begins. The clerk then reads aloud the description of the work to be done in a certain place, and the number of hands to be employed on it during the succeeding month, or for a given period, or number of fathoms; suppose it to be the breaking and raising of ores on tribute ; a voice from among the men standing below proposes to take it on the condition of receiving, say 10s. in the pound, of all the ores he may raise in the proposed time ; the captain immediately takes up a pebble, throws it into the air, reciting aloud the pro-; position he has received, and knowing by previous inspec- tion what the tribute ought to be, he proposes sometimes that which he considers to be just, or sometimes a less, in order to allow him to rise a little in price as the workman falls in his demand ; or he says to him, shall I put it to you at 7s., which he knows to be just, and the men knowing it to be so as well as he, commonly accept his first offer ; the taker of the bargain then gives in the names of his com- panions in it, which are immediately registered in the bar- gain book 5 and thus the setting as it ig termed proceeds Of the Methods of Mining in Cornwall. 205 till every part is set, that the men are willing to take at what the captain considers to be fair prices : the rest are left for after-bargains. The remainder of the day, and sometimes the whole of the next, is idle to the underground people, who under a pretence of preparing and sharpening their tools generally make holiday, and thus lose time to themselves and their employers. The underground work of a mine proceeds, for the most part, unceasingly night and day, the men who take each bargain dividing themselves into three core's (corps) for twenty-four hours, each core working generally eight hours at a stretch. But it is not to be imagined that the miner resides on the mine, which is rarely the case ; he more often has to walk one, two, and even three or four miles, and from habit, whether by day or night, is to him of little importance. Having arrived on the surface of the mine, he proceeds to the shed or the room in which is housed the chest containing his clothes and tools ; and after changing his ordinary dress for the coarse woollen garb used by the underground men, he descends the ladder by the light of a small candle held in a piece of clay by means of the fore finger and thumb of one hand, and with others to replace it when exhausted, depending from the button of his garb; his tools being slung over his shoulder,* The ladder he descends is of course nearly upright, being fixed to the side of the shaft, and may vary from twenty to thirty feet in length ; at the bottom of it is a single plank * The tools taken down by the miner (unless he have the opportunity of sending them down by the bucket or kibble) consist chiefly of his borers, or as he terms them balers, used in boring the rocks, and the substance of the lode when very hard, for receiving the charge of gun- powder used in blasting them. The borer, when the rock is hard is soon blunted, and is then brought to the surface to be repaired : in using it, the borer is held by one man, while another strikes it with a sledge hammer of about six pounds weight. The most common tool of the miner is his pick, which has a wooden handle resembling that of the pick-axe, but the iron head has but one point, the other being, as it were, cut off", and left blunt, so that the instrument answers the purpose* both of a pick-axe and hammer. 206 Of the Methods of Mining in Cornwall. placed horizontally to receive him, he then seizes the top of the next ladder, and so on, until he reaches the place of his destination, or a point from which he may branch off to his work through a horizontal level not sufficiently lofty perhaps, to prevent his stooping as he walks ; and it is commonly the case that he works his stem of eight hours, after walking from his home, and to which he also returns, without refreshment of any kind ; and when it is considered that he works always in a damp atmosphere, frequently with his feet in Mater and his clothes perfectly wet, his occupation will not be envied, but on the contrary, sen- sations of pity will be excited that hjs labour should be so inadequately rewarded. If however his work allows him what he terms wages, he is commonly at least as well satis- fied as the ordinary run of men, the extent of his ambition being the attainment of an agency or captainship, for the captains of the mines are generally raised to that statioq from the ranks. As the prospects and quantities of ores increase, the multiplication of shafts and levels necessarily follows, until perhaps in the course of two or three years, the few super- ficial acres forming the area of the mine, on which when operations were commenced not even perhaps a hovel was to be seen, are now converted into a busy scene, and are covered by the machinery of the mine and the necessary erections for the accommodation of steam engines, water wheels, horse whims, stamps, counting house, sheds, tim- ber house, coal and iron yard, the whole of which, if the directors be wise, are completed in the most economical manner, always however with a reasonable attention to stability, and the probable duration of the mine. There is generally in each mine of consequence a superior or directing captain, who inspects the workings of the mine as often as may be needful, and having under him others who are termed underground captains, because their prin- cipal business lies beneath the surface, and these propose to the former any thing that may appear to them of general utility, and sometimes consultations are held on important Of the Methods of Mining in Cornwall. 207 points. Besides these, there are also others who superin- tend affairs on the surface ; these are termed Grass captains; and others again who superintend the sorting and dressing of the ores ; and there is commonly a clerk and one or more assistants as the case may require. An engineer has the care of the engine, a timberman looks to the due sup- port of the shafts, and levels and ladders, & pitman attends to the pump work and machinery under-ground, and a material man receives and gives out the materials, bought for the service of the mine, arid places them to their proper accounts. The purser receives the money for the ores sold, makes calls on the adventurers when requisite, or what is far more agreeahle to all parties, pays their dividends when due, having first deducted all expenses, as well as the lord's dues. The accounts are generally made up every two months, and a meeting of adventurers decides on the amount of the call, or of the dividend, and the most active and intelligent of them have of course a sort of super- intendance of the mine ; the scheme of working it being however for the most part, wisely committed to the skill, experience, and integrity of the superior captain, and his assistants. The miners are settled with once a month ; but as it would be inconvenient to them to work the whole time without some advance of money, a day is appointed on which they receive a proportion of their probable earnings for the month ; which is paid in rotation by the purser or cashier of the mine, to the men who attend at the counting-house to receive it; the term for this among the miners, is subsist, or more shortly, sist. In and on very extensive mines, 1000 to 1500 men, w r omen and children are employed. The men, and the elder boys alone descend the mines and work underground ; the women break to pieces the ore with hammers, and the children pick it over and sort it. The men alone are for the most part the takers of the bargains, and employ the women and children. The best ores are at once bruised small by the double-handed hummer, and put to pile , being Of the Methods of Mining in Cornwall. in that state merchantable ; the inferior are broken by single-handed hammers and sorted, the poorest are com- mitted to the stamps , which are piles or beams of wood shod with a heavy mass of iron, and raised and let down alternately by means of an axle turned by a water wheel, and bruised so fine that the whole mass has, after being washed, the appearance of slime, and in this condition it is sold. An establishment resembling that which has been no- ticed, rather than described, will imply that the mine is both rich and profitable ; but it does not always follow that a mine yielding a large quantity even of good ores, is a profitable one to the adventurers. The lord, the agents, the miners, and the merchants, must be paid their dues, their wages, and for their merchandize, whatsoever may be the case with the adventurers. Sometimes, owing to the great depth of the mine and consequent expensive nature of the undertaking, little or nothing is left for profit. There are several mines in the county of which the monthly expenses vary from ^2000 to ^3000 ; and there have been instances in which the amount has been from ^5000 to ^6000. Now as the general run of the copper ores of Cornwall, which are mostly of the variety termed by the mineralogist Yellow Copper ore, scarcely equal on an average the price of Eight pounds per ton, it will necessarily follow that to pay expenses so very considerable, and also the dues to the lord of the soil, that the quantity of ores raised and sold monthly , must be very great : and from some few are raised every month from 5 to 800 or 1000 tons, which as before noticed are merely broken up by the hammer and sold in that condition to the smelter : and in order to render the whole intelligible, it will be requisite to make a few obser- vations on the mode of taking samples of the ores, and on the mode of sale. On each mine a considerable plot of ground, or more than one is allotted to the reception of the ores when reduced to a merchantable state ; and in this state they are left, generally unwatched, in the open air. The " pile" of Of the Methods of Mining in Cornwall. 209 ore, or rather " dole," when ready for sale, is generally made in a circular form, two to three feet thick, and with a flat summit, and consists of ores raised by the tributers sometimes in different parts of the mine (each tributer's work being duly weighed and sampled before it is put to 6 pile'), and consists of 20 to 100 tons or upwards, according to circumstances. Notice of the sampling day having been given, the agents of the Smelting Companies (being about twelve in number), or such as chuse to attend, meet on the mine to see the samples duly taken and to receive one each. The dole is then divided and subdivided, until by common consent, the whole is turned over and mixed sufficiently to satisfy all, that the few ounces taken by each is a fair sample of the whole. The sample is then tried, in the dry way by the agents of the buyers separately, and on a given day, the agents of the companies, and of the mines, of which the ores are to be sold on that day 3 assemble after due notice, at an inn in a neighbouring town, when the agent for that mine which has the greatest quantity, for sale generally takes the chair, and business proceeds by the agents of the smelting companies writing, each on a slip of paper, or ticket, the prices he means to offer, and does thua offer, for the first parcel, and so on for the various parcels, each being publicly declared, the highest being considered as the buyer ; and if two companies happen to offer the same terms, whicli is not very uncommon, the parcel is divided between them. This is termed a ticketing, and the busi- ness being concluded, the whole party adjourns to a sub- stantial dinner ; of which the expenses are defrayed by the mines, in the proportion of the quantities of ore they sell on that day. The Copper ores of Cornwall are not smelted in the county, in which coal is not found, but are shipped, gene- rally at the nearest port to the mine, for Swansea, near to which the principal smelting companies have their establish- ments. Formerly there were one or two companies which smelted in Cornwall, but it seems to have been found by experience that it is less expensive to carry the ore to the 110 Of the Methods of Mining in Cornwall. coal, than to bring the coal to the ore. The ore is taken on the backs of mules to the port, or in carts, or in one or two instances by a rail road ; and in return coal is brought to the mine, shipped from Wales in vessels which take back copper ore. Such then is the general outline of the manner in which the miner of Cornwall proceeds in discovering, working, sampling, and selling his ores. The results of his under- taking, laborious as it is to the workman, and hazardous to the adventurer, is extremely precarious, but the con- sequence is generally extreme, either much profit or great loss. There is no certainty beyond the present moment. Veins that promise much in their beginning, sometimes lose all traces of advantage below, and end in immense loss to the adventurers, or continue to be wrought for many years only under promising symptoms, but with little or no profit. The symptoms discernable in the veins, for they rarely find ore much above the level of the sea, form the only reasonable basis for the expectation of profit; but these often deceive the most experienced miner, even when they offer the most favourable prospects of success ; and on the contrary, many veins and mines which promised little or nothing in the estimation of experienced men, have yielded immense profits. Hence, although great losses often occur ? great profits are sometimes made, and even to an amount which far outstrips the expectation of the most sanguine. It has been stated that in connexion with the mines of Cornwall, the capital employed is estimated as follows : In the working of the Mines ^1,000,000 In the Wharfs, and trades dependent on them 120,000 In Waggons, Carts, Horses, &c 100,000 Smelting Works and Mills 1,000,000 Collieries 100,000 Shipping. 120,000 ^2,440,000 R eduction of Ores Gold. 2 1 j That the number of persons employed in connexion with them is as follows : In and on the Mines. 60,000 Carriers , 2,500 Sailors 2,500 In the Smelting Works 6,000 Boatmen 5,000 . In all 76,000 Copper ore to the amount of about One Million sterling is raised and sold annually. PROCESSES FOR OBTAINING THE PRINCIPAL METALS BY THE REDUCTION OF THEIR ORES. The modes by which the most valuable metals are reduced from their ores to the pure state, in which they minister so essentially to the necessities and pleasures of man, must possess a degree of interest to every one desirous of attain- ing some acquaintance with Mineralogy and Geology. The operations of the smelter in some sort connect the objects of science with those of the comforts of life. The following notices of the methods most commonly employed in reducing ores, however, are far too brief to include a detail of all the niceties attendant on the opera- tions. Some would be useless except to the operative smelter, while others are known only to the experienced in the process, and are perhaps scarcely communicable but in practice. The following pages therefore, are only to be read as introductory to a more complete information on the subject, if the reader should incline to pursue it in works of more elaborate detail. Reduction of the Ores containing Gold. Gold is not found mineralized, as it may be termed, by any other substance, but is either in the pure state or com" 2 D * Reduction of Ores Gold. bined with some other metal, in the form of an alloy, as with silver, more rarely with copper, and is occasionally involved or included in iron pyrites, as in Transylvania; and in galena, as in Hungary, thus forming the proper ores of gold : the proportion of gold is however commonly very Although the greater part of the gold annually procured, is washed out of diluvial deposits, it is also found pure in veins, most abundantly in Brazil. Peru and Mexico; but the Transylvanian mines also yield native gold in small quantities, and as in this case it is procured only by the labours of the miner, we shall notice the mode by which it is wrought and reduced. In Hungary, the whole contents of the vein holding small particles or strings or little nests of natrce gold^ are brought to the surface, broken to small pieces, and care- fully sorted, the smallest visible grain being detached from the matrix, which is chiefly of quartz. The poorer parts are then stampt, as in the case of tin, by beams of wood shod with iron at the lower extremity, alternately lifted by the action of a water wheel, and let down upon the ore until it is crushed to a powder upon an iron plate. This powder being put into a proper vessel is damped by throw- ing water containing salt upon it: and a quantity of mer- cury being put into a porous leather bag, is then forced through the pores, and dropping on the damped powder in this minutely divided itate, is kneaded up with it. The paste is then rubbed by means of a wooden pestle to expe- dite the incorporation of the mercury and gold : it is after- wards heated in a proper vessel to about the temperature of boiling water for three or four days : the mixture is then washed carefully by small parcels at a time, so that the earthy particles are washed off, leaving oni . rcury combined with the gold in the state of an amalgam. Part of the mercury is then separated by pressure in a leather bag, and the rest is driven off by distillation, leaving be- hind the gold, and also any portion of silver with which it may be alloyed. Reduction of Ores Gold. 2 1 3 The ores of gold-) that is, the iron pyrites, galena. &c. in which the small portion of gold they contain is intermixed In invisible particles, are broken up by hand into small pieces, and then placed beneath the stamps to be reduced to powder, which is carried by a stream of water to a series of pits in which the heaviest particles subside, the earthy and lighter being carried away by the current, the heaviest, namely, those of the gold, stopping the soonest. After repeated washing, the metallic part, consisting chiefly of iron pyrites and galena, are roasted in a reverberatory fur- nace, after being mingled with a proportion of quick lime, at a red heat, but not so as to fuse the mass, until part of the sulphur is driven off; the fire is then increased, and the whole brought to a state of thin fusion, and then let out into a mould of sand. During the fusion, the iron, on account of its powerful affinity for sulphur, resumes the portion of which it had been deprived by previous roasting, by decomposing the sulphurets of lead, copper, &c. with which it is mixed; in consequence of which these metals by their specific gravity fall in drops through their vitreous ferruginous scoria, carrying with them the gold and silver, and unite at the bottom in a dense metallic mass. Hence the pig that is formed in the mould of sand is found to consist of two parts adhering to each other, but easily separable by the hammer ; the uppermost and largest por- tion is cellular, and consists of scoria, beneatli which is a black heavy compact mass containing the gold and silver, together with lead, copper, some sulphur and iron : it is now broken into small pieces and roasted and fused once or twice more, until the sulphur and other impurities are got rid of, nothing remaining but the gold, silver, lead and copper. The separation of gold from lead and other metals is by Cupellation. The cupel or test is a porous, infusible, earthy mass, with a hollow concavity at the top for the reception of the metals : this being placed in a furnace so as not to h< in r.>ntar-t with the burning fu< 1, and a current of air at the same time passing o\er the surface of the test, the 214 R eduction of Ores Silver. metal is brought almost to a state of ebullition. At this temperature the lead is separated from the gold in the form of a vitreous oxide, which, sinking into the pores of the test, leaves the gold behind, nearly in a state of purity, this latter metal being incapable of oxidation at any tem- perature by simple exposure to heat and air. Reduction of the Ores of Silver. In Great Britain, there have been but few instances in which the lodes have yielded ores of silver, properly so termed, that is to say, such as have been wrought for silver alone, or for that metal in combination with other ores, which, instead of being valuable to the smelter, may pro- perly be termed impurities. For the most part the silver found in this country is intimately mingled with galena; the mode of their separation is noticed under the descrip- tion of the method commonly practised in reducing the ores of lead. Two modes of reducing the ores of silver and separating that metal from them, are practised in other countries 3 Fusion and Amalgamation. A. By the Furnace. As an example of treating the proper ores of silver, the following abstract of the processes employed at Allemont in France, under the direction of Schrieber, is given in Aikin's Dictionary of Chemistry, &c. The ores, where rough, are chiefly native silver, and the sulphuret of silver, mixed with a little arsenical cobalt, with pyrites, with iron ochre, with clay, calcareous spar, and other earthy mine- rals. Much of the silver is in extremely minute grains dispersed through the gangue so as to render it impossible to separate the stony parts by washing. The ore therefore after being picked by hand is pounded dry in a stamping- mill and is thus reduced to the consistence of a coarse sand ; In this state it is assayed, and contains on an average about of iU weight of silver. As it holds DO superfluous Reduction of Ores Stiver-. 214 quantity of sulphur there is no necessity for roasting it previous to fusion. On account of the refractoriness of the ore, it is expedient to make use of quicklime, scoriae from a preceding fusion, and slag from the iron forges by way of flux; and in order to furnish the proper quantity of lead of which the ore is naturally entirely destitute, it is ming- led with pulverized galena, with the litharge and scoriae furnished by the refinery, and with old cupels ground to powder, in such proportions that the lead obtained by the fusion should contain 2 per cent, of silver, allowing at least 20 per cent, of the lead to be lost by evaporation or com- bining with the scoriae. The above materials being pro- perly mixed together are put into a powerful blast furnace, with alternate charges of charcoal, and the products of the fusion are lead holding silver, a black compact sulphureous semi-metallic substance called Matt, and scoriae. The scoriae undergo no further treatment, except that a certain portion is reserved as a flux for the next parcel of ore ; the matt being tolerably rich in silver is remelted with litharge, and the lead obtained carries with it nearly the whole of the silver, so that it is not worth while to fuse again this second matt, although it still contains a portion of precious metal. The lead procured by'these operations when refined yields about 2 per cent, of silver ; the cupellation is per- formed at a higher heat than usual, which perhaps is ren- dered necessary by the presence of a little iron, the conse- quence of which is, that the loss of metal by evaporation, instead of being about 7 or 8 per cent, amounts at least to 20 per cent, and as every pound avoirdupois of the lead thus volatilized contains from 6 to 10 grs. of silver, the loss in this process is prodigious, and might in all probability be greatly diminished by the mixture of a much larger proportion of lead with the silver ore. B. By Amalgamation. Such ores as contain silver in the native state, or com- bined with sulphur, are best adapted to the process of 2 1 6 Reduction of Ores Silver. amalgamation. Such as are rich also in lead or copper are smelted with most advantage. Sulphur seems essential to the process, a large proportion of iron pyrites is therefore desirable. Ores containing 70 to 80 ounces of silver in the ton are best adapted for amalgamation, and it is an object to attain about this average by mixing different ores, having regard to the quantity of sulphuret in them, which should amount to 35 per cent., about one half of which is sulphur : 10 per cent, of common salt or muriate of soda is added to the ore, and by means of the salt, a chemical change is effected during the roasting of the ore in the furnace. The sulphur becomes acidified, and the acid thus formed, uniting with the base of the salt, forms sulphate of soda, while the muri- atic acid of the salt, thus set free, combines with the silver of the ore that was not in the metallic state, and forms muriate of silver. In this state the ore is subjected to various mechanical operations, with riddles, screens, mills and sieves, until it is reduced to an impalpable powder. It is then submitted to the action of mercury, which is the actual process of amalgamation. This is performed in barrels, so arranged as to revolve on their axes. The mixture or charge in each barrel, consists of sifted calcined ore (composed of sulphate of soda, muriate of silver, muriate of iron, and other metals and earthy matters) mercury, metallic iron, and water in certain proportions. During the process of amalgamation, the barrels are made to revolve during sixteen or nine- teen hours, and the muriate of silver becomes decomposed by the action of the iron on its acid, and the silver, thus reduced to the metallic state, combines with the mercury, forming an amalgam, whilst the sulphate of soda, the mu- riate of iron, and other salts become dissolved in the water. The amalgam is then filtered, by which the surplus mer- cury is separated, and a compound remains in the sack consisting of six parts of mercury, and one of silver. This amalgam is then subjected to the action of heat in a dis- tilling furnace, by which the mercury is driven off and Reduction of Ores Iron. 217 V sublimated, and the silver remains. The silver is then col- lected, and melted in a crucible, but as it contains a portion of other metals that were combined with it in the ore, it is afterwards refined in a cupel, or testing furnace. It may however be added that in consequence of the immense speculations in the silver mines of America, where amalgamation is almost exclusively employed in the reduc- tion of ores, the attention of our chemists have of late been much turned to the reduction of silver ores by new methods, some of which are said to succeed, and if that should be found to be the case, an enormous expense will be saved in reducing them, there being no quicksilver used in any of the new processes, Reduction of the Ores of Iron. In most European countries in which iron is manufac- tured, the ordinary fuel employed in the smelting of it is charcoal, and hence some foreign irons, particularly the Swedish, is much prized by the English manufacturers of steel from its superior purity. Something however is pro- bably to be attributed to the nature of the ore, which is a very pure magnetical (oxide of) iron, In Britain there are but few charcoal furnaces. It is by no means intended to enter into the minute par- ticulars of the various modes that have been, or now are adopted for the reduction of the several varieties of iron ores, but only to give a very general outline view of the mode commonly adopted for obtaining the metal from the most abundant of our ores, which is the common iron-stone of our coal-measures. This ore is found in small lumps or layers, lying in the clay which separates the beds of coal; it is an impure carbonate of iron. The ore is first reduced to pieces about the size of an egg, and is sometimes roasted, which is the first operation, in cup-shaped kilns having lighted coal at the bottom, on which the iron ore is heaped so as to fill the kiln, and the roasting is generally complete by the time the coal is com- More commonly however the roasting is performed 2 E- 218 Reduction of Ores Iron. on the ground : four to eight inches in thickness of coal is first laid down, on which is placed a layer of broken iron- stone 18 inches to two feet thick; two inches of small coal is then laid on the ore, and on this a pile of ore diminishing in size so as to assume the form of the ridge of a house, and the whole is then covered by small coal and coal dust. The lower stratum of coal is then lighted, which by degrees ignites the whole mass. The pile is at bottom 30 feet to 60 yards long, 10 to 16 feet wide, and about five feet high. In a few days the iron-stone is cool ; is become of a red or reddish brown colour, and the sulphur, carbonic acid, water and inflammable matter, being driven off, it has be- come magnetical and is fit for the smelter. The furnace in which it is smelted is upwards of 40 feet high, and is built of the strongest masonry, externally of the form of a trun- cated four-sided pyramid, internally of a peculiar con- struction, and lined partly by fire bricks and partly by a sandstone [millstone grit], and into which, when charged, air, in a high state of compression, is forced. It is a blast furnace, and is charged at the chimney by regular intervals with coak, iron ore and limestone in the proportion of about 4 of the first, 3.J. of the second, and 1 of the third by weight, and is always kept so charged to a certain height. In somewhat more than 48 hours the whole runs down, and the iron is melted, and in that state is suffered to flow out into furrows made in sand, where it forms pig iron^ or into a large reservoir, whence it is poured by means of ladles into moulds, forming all the various articles of cast-iron ware, from cannons and steam-engine boilers, to fire grates and common iron pots. Of cast iron, the manufacturer has four sorts ; the first, most highly partaking of the carbonaceous matter with which it was smelted, bears the highest price. 1. moothfaced Iron, No. 1 of the manufacturer. This is considered as being composed of iron nearly saturated with carbon, and mixed w ith a comparatively small portion of oxide of iron and earthy impurities. Its upper surface Reduction of Ores Iron. is smooth and convex, entirely free from oxide, and often covered over by a thin crust of plumbago ; it presents a coarse granular fracture with a brilliant metallic lustre and dark blue colour. 2. Good melting Pig Iron, or No. 2 of the manufacturer. This diifers from the preceding in containing probably a smaller proportion of carbon and a larger admixture of oxide of iron. Its upper surface is slightly convex and full of small cavities : its fracture is coarse granular towards the centre of the pig, but the grains manifestly diminish in size as they are situated nearer the surface ; its colour is dark grey inclining to blue. 3. Grey Iron, or No. 3 of the manufacturer. In this the amount of carbon is still less. Its upper surface is level, sometimes slightly concave, and presents more and larger cavities than the preceding ; it is slightly oxidated superficially , its fracture is fine grained, and its colour light grey. 4. White Iron y Forge Pigs, Ballast Iron. In this there is still less carbon, and more oxide of iron. Its upper sur- face is concave, rough and covered by a plate of oxide ; its texture is compact, sometimes tending to the striated ; its colour is tin-white, occasionally mottled with grey. Cast iron is converted into Bar iron by smelting it two or three times by means of charcoal in a refinery ; by this process the scoriae is got rid of, the brittleness of the cast- iron is lost, and the iron receives the new character of malleability when converted into bar iron, which before it assumes that denomination, undergoes repeated weldings and hammerings, and finally splitting. The toughest of all is that termed Stub-iron, used in making the barrels of fowling-pieces, and is prepared in the following manner. A moderately broad ring of the best Swedish iron is placed horizontally, and filled with old horse shoe nails (called 2s 2 220 Reduction of Ores Iron. stubs), set perpendicularly, till it can hold no more,' a pointed bar of iron is then driven into the centre of the circle, and thus locks the whole together. A welding heat is then applied, and the mass is hammered very gently at first, till the nails and ring become completely united ; it is then drawn into bars, and affords an iron of peculiar closeness, toughness and malleability. Iron is converted into Steel by a process termed cemen- tation, which consists in subjecting iron in contact with charcoal in alternate layers to the action of heat in a close furnace for several days. Steel combines the fusibility of cast iron with the malleability of bar iron, and further pos- sesses the valuable property of becoming intensely hard when suddenly cooled, and is therefore much superior to common iron for all kinds of cutting instruments, files, and various other tools. Cast steel is prepared by melting common steel in a crucible with a flux composed of car- bonaceous and vitrifiable ingredients \ it is still more highly carbonized than common steel, as well as more brittle and fusible, and being harder, of more uniform texture and closeness of grain, is the material of all the finest articles of English cutlery. The hardness of steel depends on the degree of coldness of the water into which it is suddenly plunged when as red hot as it can be made without melting ; and it is tempered by being again heated in an inferior degree and according to the temper required ; and it is remarkable that whether it be now cooled suddenly or gradually is unimportant. While tempering, its surface displays a succession of co- lours (supposed to arise from a commencing oxidation) in proportion as it becomes more and more heated, which the workmen have ingeniously taken advantage of as indicating, and serving to denominate, the degree of temper required for different articles. An old and still common method of tempering is to lay the articles on a clear coal fire, or on a hot bar, till they exhibit the requisite colour ; but small articles to be reduced to a blue temper are commonly dip- R eduction of Ores . Tin . 221 ped in oil or melted grease, and then held over a fire till the oil becomes inflamed and thus evaporated. Steel, when subject to the heat of 430 to 450 degrees, assumes straw yellow tints, and is the temper for razors, and other articles with a keen and delicate edge. 470 degrees, assumes a full yellow tint, and the temper for scalpels, penknives, and other fine edged instruments. 490 degrees, assumes the brown yellow, and is the proper temper for scissors and small shears. 510 degrees, assumes the first tinge of purple, and is the temper for pocket and pruning knives. 530 degrees, assumes the purple tint, and is the temper for table and carving knives. 550 to 560 degrees, assumes the different shades of blue, and is the temper for watch springs, swords, and for such instruments as require great elasticity. 600 degrees, assumes a black hue, indicating the lowest degree of temper. Reduction of the Ores of Tin. The only ore of tin is an oxide^ and is found interspersed through some parts of the veins of Cornwall in small crys- tals accompanied by masses of the slate or granite of that country, sulphurets of iron and of copper and arsenical pyrites, quartz, and occasionally tungstate of iron and other minerals. It is commonly blasted by gunpowder, and brought to the surface in pieces of considerable size which are stamped to a fine powder by means of upright beams of wood loaded with iron below, and alternately lifted by- means of machinery turned by a water-wheel. When thus stamped it has the appearance of slime, and is afterwards washed, on a wooden frame, termed a huddle ', the stream of water carrying off the lighter earthy particles and leaving the more weighty grains of tin, which after repeated wash- ings, are in a state fit for the smelting-house, and being Reduction of Ores 1 in. still more or less mingled with the metallic minerals with which it was accompanied in the vein, it is (being now in the state termed black tin) roasted at a low red heat in a reverberatory furnace, to volatilize the arsenic, and drive off the sulphur. It is then of an ochry red colour owing to the oxidation of the iron and copper. It is again washed and the impurities separated from it, and is then reduced by placing it in a reverberatory furnace about 7 feet long and 3^ wide, 7 to 15 cwt. of the roasted ore being mixed with about one-fifth of Welch culm (or small coal) and in some cases a small quantity of slaked lime, the whole being turned over and moistened with water ; a brisk fire is then applied for about six hours, the tin sinking, as it becomes reduced to the bed of the furnace, beneath a covering of boiling black scoriae. The furnace is then tapped and the melted tin suffered to flow, in a small cavity at foot of the furnace. When that is done the scoriae are raked off and a new charge of roasted tin and culm thrown in. When the metal in the pit is red hot it throws up a quantity of slag very rich in metal, which is immediately returned into the furnace ; and when the melted tin is become sufficiently cool it is taken out with iron ladles and poured into moulds of granite, where it consolidates, each charge affording on an average from 4 to 5 cwt. of metal. The first scoriae being without metal, are first stamped, afterwards washed to separate the richer particles, termed Prillion^ and are then mixed with the roasted ore. .The melted tin thus procured is next placed without any addition in a small reverberatory furnace and exposed to a very gentle heat ; the purest part melts first and is drawn off, forming the common grain tin ; the more refractory part, containing a small and variable proportion of copper and arsenic, is then melted and cast into pigs of common tin, or block tin. The finest grain tin however is procured from the stream works of Cornwall ; so termed because the rubble or allu- vium with which the loose crystals of oxide of tin are found either mixed or covered in some of the low grounds of Cornwall, are washed away by means of passing streams of Reduction of Ores Tin. 223 water over the whole. When this simple process is ac- complished, the tin is collected, and being in separate crystals free from the impurities of vein-tin ore, is ready for the furnace after being broken small enough to pass through iron sieves containing 16 meshes in the square inch. The furnace is termed in Cornwall a blowing-house, and is a blast furnace of the simplest construction about seven feet high, and supplied with air from two cylinders, worked by a water-wheel. The only fuel made use of is charcoal, and after the furnace is heated, it is fed at short intervals with three or four shovels of ore, and two or three half shovels of charcoal, no flux of any kind being em. ployed. At the bottom of the furnace is a small channel through which the reduced tin is constantly flowing into a pit below, accompanied by a small quantity of slag, which is removed from time to time, and thrown again into the furnace. When the pit is full of tin it is ladled out into an iron boiler, about three feet in diameter, with a small fire under it to keep the metal sufficiently fluid ; two or three large pieces of charcoal, which have been soaked in water, are then laid upon the tin, and plunged to the bot- tom by means of an iron instrument. A violent ebullition is immediately excited, and a little slag which was before mixed with the metal rises to the surface and is skimmed off. In a minute or two afterwards the metal is tried by taking up a ladle-full and pouring it again into the mass, when if it appears quite bright like silver, and of an uni- form consistence, the purification is complete, and nothing more is requisite tnan to cool it to a proper degree, and lade it into the moulds, by which it is formed into pigs, weighing from two to three cwt. each. If the metal is too hot when poured into the moulds it is apt to be brittle. Good stream tin affords from 65 to 75 per cent, of the very purest grain tin. None of the Cornish tin can be sold until it has been coined, for which purpose it must be taken to the nearest coinage town, of which there are four or five in the county ; a small piece is then cut oif from the corner of every pig and assayed by the proper officer; if of the 224 Reduction of Ores Copper. requisite purity it receives the stamp of the Duchy, and pays to the king, as duke of Cornwall, four shillings per cwt. Tin is one of the lightest of the metals in the pure state ; which appears to be owing to the form which its particles attempt to take in cooling, and which is crystalline. A block of tin may be viewed as an aggregation of minute crystals, intercepting each other in every possible direc- tion, so as to leave considerable interstices between the little plates or crystals of which it is composed ; hence its lightness, and that peculiar crackling noise in bending it, termed by the French, cri de 1'etain, Reduction of the Ores of Copper, The ordinary Copper ore of Cornwall, and indeed of ^England and Wales generally, is the yellow ore, consisting of copper, iron and sulphur in nearly equal proportions. Next to this perhaps in respect of quantity is the sulphu- ret, as it is mineralogically termed, which consists of about 80 per cent, of copper : other varieties also are found occa- sionally, as the red oxide, carbonate and arseniate, but in proportions too small to merit particular notice as regards the reduction of the ores of copper generally. The ore as prepared for the smelter, however, contains nearly 60 to 70 per cent, of earthy matters found w ith the copper in the veins. Hence it may be imagined that considerable know- ledge of the art is requisite, and dexterity in selecting and mixing those which most favor the speedy reduction of the ores : and it has been found by experience that the ores of particular mines are extremely intractable alone, and require for their reduction an intermixture with others in which ,the ore is of itself more readily fusible, or is accompanied by substances which assist in their reduction ; added to this, they are too often accompanied by mis- pickel, which is constituted in part of arsenic. Both arsenic and sulphur adhere to copper with great obstinacy, even long after it has assumed the appearance of a pure regulus, and even in small proportion they impart a brittleness to Reduction of Ores Copper. 225 copper, as well as render it hard and difficult to work: and it is most probably owing to the neglect in other coun- tries of getting rid of these impurities, that most of the foreign copper imported into this country requires refining, being too brittle to endure the rolling and hammering requisite to reduce it into thin plates or sheets. The reduction of copper ore is completed by means of eight processes. The first is that of calcining in a rever- beratory furnace, about 17 feet by 19, the bottom or bed of which is made of fire-bricks. The chimney is from 40 to 50 feet high, which causes such a powerful draught that the arsenic and sulphur separated during the roasting pass almost entirely through the chimney into the open air. About three tons of the ore are spread over the bottom of the furnace, being thrown in through a kind of funnel or hopper just above. The fuel is Welsh coal, which, as usual, is burnt at the anterior part of the furnace, and its flame draws over the surface of the ore in its passage to the chimney. In this furnace, which is called the calcining furnace, the ore is roasted without addition with a dull red heat for twelve hours, and is frequently in that time stirred with a long iron rake, introduced through a hole at the further end of the reverberatory, to expose fresh sur- faces to the action of the flame. The ore is not melted here, but when roasted sufficiently to oxidate the iron, and convert the sulphur into sulphuric acid, it undergoes the second process, namely of being melted, and for this pur- pose is carried to another furnace, about 1 1 feet by 8, and here it receives a fusing heat^ but still without any addition, except a little slag, or when the ores are very stubborn, a little fluor spar to assist the fusion. When the ore is melted, the liquid mass is well stirred, and afterwards the slag is raked from its surface. More calcined ore is then added, and when the furnace is full, it is tapped, and the melted metal flows into an adjoining pit full of water ; by which means it becomes granulated. The slags having been received into moulds are broken, and any particles of copper selected. The granulated metal now contains about 2r 226 Reduction of Ores Copper. one-third of copper, and consists of copper, sulphur and iron. Five charges are melted in twenty-four hours. In the third operation, the granulated metal is calcined to oxidize the iron, and remains twenty-four hours in the fur- nace, during which it is often stirred and turned about. The heat is at first moderate, but is gradually increased. The fourth process is that of melting after calcination in the small furnace, some slags from the last operation being added, and pieces of furnace bottoms impregnated with metal in the form of oxide of copper, which is reduced during this process ; the oxygen of the copper combining with the sulphur passes off as sulphureous acid gas, while the metal thus reduced enters into combination with the sulphuret. The slags being skimmed off, the melted metal is either tapped into water, where it is granulated, or into sand baths, when it becomes solid. Its produce in J&ne cop- per is now about 60 per cent. The fifth process is that of again subjecting the metal to the same mode of calcination as in the third process. The sixth process consists in the melting again of the metal as in the fourth process, and the result is a coarse copper containing from 80 to 90 per cent, of pure metal. In the seventh process, the metal is roasted in the smaller furnace chiefly to oxidize it, and finally to expel the volatile substances : 25 to 30 cwt. are by this process fused at the end of the operation, which continues twelve to twenty-four hours according to circum- stances. The metal is then tapped into sand beds, and the pigs in this state are termed blistered copper. It is now fit for the refinery. The eighth process is that of Refining or Toughening. This appears to be a delicate process, in which there are several circumstances on which it is mainly dependant, that are judged of principally by the eye of the workman. It is conducted in a furnace similar to that for melting, and the prime object appeal^ to be that of abstracting from the nearly pure metal the last portions of oxygen, which is performed by means of adding charcoal to the metal while in fusion, and stirring it occa- Reduction of Ores Lead. 227 tonally with a pole of birch wood, until the operator judges it to be pure. About 11,000 tons of pure copper are annually produced by the mines of England, Scotland and Ireland, of which Cornwall alone furnishes about 9000, Reduction of the Ores of Lead. The principal part of the enormous quantity of Lead annually procured in this country is obtained from galena, hi which the lead is in combination with sulphur, in the proportion of 86 parts of lead to 14 of sulphur. Other ores of lead, as the carbonate, the sulphate, and the oxide, are occasionally intermingled with the galena, which mostly contains silver in greater or less proportions, and isaccom- panied in the vein by blende, certain of the ores of iron, and sometimes of arsenic, and with various earthy sub- stances, as quartz, calcareous spar, fluor, &c. It is of course the object of the process of smelting to free the lead of all its impurities, even of the silver, when it exists in a pro- portion that will pay for the process, which purifies the lead, and makes it softer and finer. The galena being freed by the hand and the hammer from all such impurities as can be readily separated from it, is then beaten down into small pieces, and after repeated washings and cleansings, is placed in a reverberatory fur- nace at a low red heat for some hours to drive off the sul- phur and arsenic, without fusing the lead ; and when the flame on the surface has changed from blue to a reddish white, the roasting is considered to be finished, the lead being converted into an oxide. The reverberatory furnace commonly used is about 10 feet long, and six feet wide internally, and about 2-| feet deep, the fire place being at one end, from which the flame rises into the furnace. The quantity of ore usually shot into the furnace at once is 16 cwt. of one hundred and twenty pounds each, which is spread over the bottom floor of the furnace, and the doors are then closed. The roasting as above mentioned being completed in a moderate heat, a small quantity of charcoal 2 F 2 228 . Reduction of Ores Lead. is added, the doors closed and the reduction completed, the lead in a reduced state lying at the bottom of the fur- nace covered by a slag of two or three inches in thickness ; the slag is then tapped, and runs off, and is used for mend- ing the roads. -Some quick lime in powder is then thrown upon the metal in a state of fusion, which serves to raise and cake the remaining slag, which then by means of a rake is taken from the surface, and is nearly black and very heavy. The lead is then suffered to run out of the furnace into a pan, and the scum or dross being taken from the surface is thrown back into the furnace : the lead is then ladled from the pan into iron moulds, and left to cool. The whole of these operations are repeated, by means of two sets of workmen, during every seven or eight hours. Other modes of smelting lead ore are often practised, but that of the reverberatory furnace is preferred. If the lead contain silver in a proportion that will pay for the process of refining^ and which is commonly esti- mated at not less than 15 oz. of silver in the ton, it is again placed in the furnace. Refining is performed in a reverberatory furnace, the fire-place of which is 22 inches square, separated from the furnace by a partition, called the fire-bridge, 14 inches broad; so that nothing enters the furnace itself but the flame, which passes over the lead in the cupel, or test, to the two flues on the opposite side of the furnace, which ter- minates in a chimney near forty feet high. The cupel, test, or vessel, in which this operation is conducted, consists of an oval iron frame, surrounded with a ledge three inches and three-quarters deep ; its greater diameter is four feet, the lesser two and a half: it has four cross-bars at the bot- tom, of three inches and three-quarters in breadth and half an inch in thickness, as are the other parts of the frame ; the first of these bars is nine inches from the fore-part of its rim or ledge, and the other three are placed at nearly equal distances from this bar to the back end of the rim. The test-frame, as it is called, being so constructed, is beaten full of a mixture of bone and fern ashes, with flat headed Reduction of Ores. Lead. 229 iron cakers, the said head being about one inch and an eighth in diameter. The proportion of the former of these ashes (by measure) to that of the latter is from one-eighth to one-sixteenth, according to the purity of the fern ashes, which are used on account of the vegetable alkali that they contain, as it has the property of semi-vitrifying the bone ashes or destroying their friability, and making them more durable. These ashes are levigated with water, mixed up together, and beaten, as before described ; they are then scooped out with a small spade, made for that purpose, until they are left about three-quarters of an inch thick upon the test-frame bars, the sides are left two inches broad at the top and two and a half at the bottom all round the rim, excepting the fore-part, called the breast, which is five inches; a hole is cut out in this breast of one inch and a quarter in width, from the inner side of the frame, and six inches long, with which the passage or gateway, for the litharge, communicates. The vessel, or test, so formed, is put into the refining furnace, (in fact it may be called its bottom) propped up at its proper height against, or close to, an iron ring, fixed in the masonry of the furnace ; the height of the furnace roof, from this ring, is twelve inches at the. fire-bridge side, and nine at the flue. The fire must be applied very carefully for drying the test, as too much heat will evaporate the water with which the ashes were moistened, too quickly, and occasion the test to fly in pieces : but having been perfectly dried and brought to a reddish heat, it is nearly filled with melted lead, previously fused in a cast-iron pot, which takes about five hundred weight for that purpose ; but at the tempera- ture the lead is put into the test, it becomes covered with a grey pellicle, called dross, which is a mixture of the first oxide of metallic lead ; but, after increasing the heat of the furnace, the lead becomes of a whitish-red colour, and its whole surface is covered with the litharge of commerce, composed of about 91 of lead and 9 of oxygen : the bellows are then put in operation, from the hind-part of the test, 230 Reduction of Ores Lead. which forces the litharge up to the breast, and over the gateway, (already detailed) where it falls upon a cast iron plate, level with the refinery-floor, in clods, in which state it is taken to the reducing furnace to be reconverted into lead. The blast of atmospheric air, issuing through a muzzle, put over the bellows pipe, of a certain construction, not only mechanically sweeps off the litharge from the surface of the lead, but it also furnishes oxygen for its formation, the refiner taking care to command the proper heat. As the surface of the lead must be necessarily depressed, by its oxidizement to, or below, the level of the gateway, more lead is ladled in from the melting pot, to raise it to the proper height as often as that occurs ; in this manner the operation is continued until 84 hundred weight, or four Newcastle fodders of lead are introduced into the test \ and the whole of the silver in that quantity is left in com- bination with about one hundred weight of lead : this is called rich lead, and is taken out of the test. After such a number of these pieces of rich lead are gotten, as by assay, are sufficient to make a cake of silver of the weight of one to two thousand ounces, they are re-melted, and the silver is obtained in a test, of which the bottom is differently formed to that of the working test, being hol- lowed so as to receive the silver, and leave a margin of the bottom uncovered, that the slag may be raked from off the edges of the silver. Thus the lead, copper, tin, &c. may be separated from the silver, by the aid of the oxygen of the atmosphere, supplied with proper care, and continued under a proper heat, until the silver only remains. Copper is not so easily separated from the silver as the lead, owing to its great affinity to the former, and is found frequently to occur in minute portions. Tin has only in one mine been found in the refining of silver, and is extremely difficult of extrication from it, on account of its small affinity for oxygen. The litharge thus obtained by the process of refining, is far greater than the demand for it in the market 3 and hence the necessity for reducing it into lead. Reduction of OresZinc. 231 This reduction is performed chiefly by a reverberatory furnace, six feet long and about the same broad, inside; the fire place is 25 inches square, divided from the furnace by a partition or fire-bridge : it sometimes has only one and sometimes two flues, through which the flame enters an upright chimney. The litharge is carefully mingled with small coal, and the bottom of the furnace previously co- vered, about two inches thick, with coal 5 the flame from the fire-place very soon sets the coal on fire, and in a little time converts it to red hot cinders : the above mixture of litharge and coal is then thrown upon them, and, by the proper management of the heat or flame in the fire-place, the necessary temperature is kept in the furnace, to enable the combustible matter to take the oxygen from the litharge and set the lead at liberty ; which, as that is done, is received into a cast iron pot, and then cast into pieces of one hundred weight and a half, and is called refined lead.. It is superior to other lead, and obtains the highest price in the market. Care should be taken, that something short of the necessary quantity of coal is intermixed with the litharge, previous to its admission into the furnace, because the workmen, upon seeing the want of it as the process goes on, can mingle (in such parts of the furnace where it is wanted) a fresh supply of it : this is a point that should be always particularly attended to, since a re- dundancy of coal would necessarily increase the quantity of slag, at the termination of the shift, which is to be drawn out, and another charging of litharge put into the furnace, intermixed with coal as before. In this furnace six fodders of lead may be run in nine or ten hours. There is always fresh litharge thrown into the furnace during the first six hours of the shift. Reduction of the Ores of Zinc. The ore of zinc, whether calamine or blende, after being raised from the mine, is first dressed, that is, it is broken to small pieces, and the galena, pyrites, and other impuri- ties are separated as accurately as possible by the hand; 232 Reduction of Ores Zinc. it is next calcined at a moderately red heat in a reverbera- tory furnace, by which the calamine is deprived of its car- bonic acid, and the blende of the most part of its sulphur. It is then washed, by which the lighter earthy parts are separated from the metallic oxide, which latter, being dried, is intimately mixed with about one-eighth of its weight of charcoal by grinding the ingredients together in a mill, and is now ready to be smelted. The furnace in which the reduction is performed is a circular one not unlike that of a glass-house ; in it are fixed six large earthen pots, about four feet high, and nearly of the same shape as oil jars : into the bottom of each pot is inserted an iron tube that passes through the arched floor of the furnace, and dips in a vessel of water placed beneath, while the other end of the tube rises within the crucible to within a few inches of its top. These crucibles are filled up to the .level of the tube with the mixture of roasted ore and char- coal the cover of each is very accurately luted on, and the furnace is charged with fuel, by which an intense heat is kept up for several hours. The zinc, as it is reduced, ascends to the top of the pot in the form of vapour, and there being prevented from escaping by the closely luted cover, it descends through the central iron tube, whence it passes into the water, and is there condensed in small drops. These globules are afterwards melted and cast into ingots, in which state they are brought to market. Common zinc generally contains a little lead, copper, arsenic, iron, manganese, and probably plumbago, which often considerably impair the quality of the alloys into which it enters. In order to get rid, in part at least, of these impurities, the common practice is to melt the zinc in a crucible, and then to stir into it, by means of a stick or earthen rod, a mixture of sulphur and fat : the latter of these preserves the zinc from oxidation, while the former, uniting with all the metals present, except the zinc, con- verts them into sulphurets, which rising to the top form a scoria that may be skimmed off : this is to be repeated as long as any scoria makes its appearance. Reduction ofOresPlafma. 233 Reduction of Crude Platina. The great infusibility of Platina, added to the strong resistance which it opposes to common menstrua, long ex- cited the attention of chemists and artists, and has given birth to various ingenious processes for condensing this refractory metal into malleable masses, and' forming of it crucibles and other instruments of material service to the accuracy and simplicity of chemical analysis. If the largest and whitest grains are carefully selected from a parcel of crude platina, it will be found that these are considerably malleable even when cold, and still more so when hot : also if two grains are laid in contact with each other and then brought to the highest possible white heat, they may be made to adhere more or less perfectly by a stroke with a hammer, and in this way, by great patience and great dexterity, it may be practicable to form a few grains into a mass. This however is by much too imperfect and tedious a method to be employed with any practical ad- vantage. The following method of fusing and purifying crude platina is said to be attended with complete success : The platina being dissolved in nitro-muriatic acid, the liquor is to be filtered through clean white sand, in order to separate the black powder which floats among it. The clear solution being then decomposed by sal-ammoniac the yellow precipitate is to be collected, moderately well washed in warm water and dried. It is then to be dis- tributed into saucers which are placed in a small oven constructed for the purpose, where they are exposed for a short time to a low red heat in order to bring the platina to the metallic state, and to drive off by sublimation the greater part of the muriated ammonia. When withdrawn it is a spongy mass of a grey colour. About half an ounce of the platina in this state is to be put into a strong iron mould about 2| inches long by 1^ wide, and is to be com- pressed as forcibly as possible by striking >vith a mallet upon a wooden pestle cut so as accurately to fit the mould : 2 i; $34 Reduction of Ores Mercury. another half ounce is then added and treated in the same manner, and so on till six ounces have been forced into the mould : a loose iron cover just capable of sliding down the mould is then laid upon the platina, and by means of a strong screw press, almost every particle of air is forced out from among the platina. This is a part of the pro- cess that requires especial care, for if any material quan- tity of air is left in the mass, the bar into which it is formed is very apt in the subsequent operations to scale and be full of flaws. The pressure being duly made, the mould is to be taken to pieces, and the platina will be found in the form of a dense compact parallelepiped. It is now to be placed in a charcoal forge fire and heated to the most intense white heat in order completely to drive off the remaining ammoniacal muriat ; this being done it is to be quickly placed on a clear bright anvil and gently hammered in every direction by a clean hammer. This is to be repeated several times, at the end of which the mass will be perfectly compact, and fit to be laminated or wrought in any other manner that the artist chuses. It is to be observed that while the platina is heating it must lie loose in the fire, for if it were held by the tongs they would infallibly become welded to the platina, and thus greatly damage it. By the time that the platina is thus drawn down to a compact bar it will be covered by a some- what reddish semivitreous crust proceeding chiefly from particles of the ashes melted down upon it and extended over its surface by the hammer. To remove this, the bar being made red hot is to be sprinkled over with pulverized glass of borax, and then kept for a few minutes at a white heat ; when moderately cool it is to be plunged into dilute muriatic acid by which the borax and other vitreous mat- ter will be dissolved, leaving the platina with a perfectly clean white surface. Reduction of the Ores of Mercury. The modes of extracting the metal from the ores of mer- cury are very simple. The one that we shall mention is Reduction of Ores Manganese. 235 the best and most scientific, and practised at the mines of Deux Fonts, and of Idria. The ore being brought out of the mine, is sorted by hand with considerable accuracy, rejecting those parts that appear to be destitute of metal. This is an expensive and rather tedious process, but has superseded the ancient method of separating the cinnabar by washing, on account of the prodigious loss of metal in that operation. The sorted ore being reduced to powder, is carefully mingled with one-fifth more or less, according to the proportion of cinnabar contained in the ore, of quicklime which has fallen to powder by exposure to the air. This mixture is then put into iron retorts, capable of holding about 60 Ibs. weight, which when thus charged, are fixed in a long furnace, to the number of 40 or 50 : a glass receiver being then attached to each retort, but not luted, a gentle fire is applied in order to drive out all the moisture ; when this is effected, the juncture of the vessels is closely stopped with tempered clay, and a full red heat is applied for seven or eight hours, at the expiration of which time all the mercury will have been volatilized and condensed in the receiver. The common produce varies between six and ten ounces of metal from 100 Ibs. of the ore. Reduction of the Ore of Manganese. As manganese is applied to no use in its metallic state, there are no establishments for the reduction of its ores in the great way ; and even in the laboratory the process is seldom performed, chiefly on account of the intense heat which is requisite, and which cannot be obtained in small furnaces unless they are peculiarly well constructed. The use of all alkaline and vitreous fluxes must be carefully avoided ; for the affinity of these with the oxide of manga- nese is so considerable as entirely to prevent its reduction where they are present. The only method which has been attended with any tolerable success is the following, in- Tented by Bergman. Select a sound and very refractory crucible and line it with charcoal, or still better with a 236 Reduction of Ores Antimony, mixture of linseed meal and water, beaten up with as much finely sifted charcoal as it will take without losing its tenacity, dry the crucible thoroughly, gradually increasing the heat till the meal begins to be scorched ; then take some oxide of manganese (which is first to be quite puri- fied from all extraneous substances) and make it up in- to a ball with any kind of oil; put this into the cavity of the crucible and cover it with powdered charcoal; then lute on a pierced cover or an inverted crucible, and place it in a blast furnace ; keep it at a moderate red heat till the jet of blue flame through the hole in the cover has ceased, then bring the furnace rapidly to its highest heat, and keep it so for forty minutes or three quarters of an hour : after this let the fire go out, and when the crucible is quite cold break it up carefully, and the manganese will be found in globules of various sizes covered for the most part with a thin vitreous crust. It appears probable that a button might be obtained by a second fusion of these globules with glass of borax, in a crucible lined with char- coal and a little pipe-clay to prevent the flux from sinking through the pores of the charcoal. Reduction of the Ores of Antimony. The only one of the ores of antimony that is found in sufficient abundance for the preparation of pure antimony from it, is the sulphuret. This is first broken into small pieces in the same manner as the ores of copper, by hand, and then placed in a reverberatory furnace to undergo simple fusion, being first covered by charcoal powder : a low red heat suffices to fuse or melt the antimony, without driving off the sulphur ; the earthy parts floating on the mass in fusion are taken off by means of a rake ; the anti- mony is then cast in moulds, and forms the common or crude antimony of commerce. There are several modes of procuring pur^ antimony from crude antimony. The following is the most common process in the large way. The crude antimony, broken into small pieces is strewed on the floor of a reverberatory Reduction of Ores Arsenic. 237 furnace, for the purpose of driving off the sulphur by roast- ing without melting the mass, for which purpose a gentle heat is first applied : a blue flame, arising from the com- bustion of the sulphur, is first apparent on the surface, while the ore during its conversion into an oxide loses its metallic lustre. By stirring the ore sufficiently during an increase of temperature, it will in some hours bear a mo- derate red heat without melting, its fusibility decreasing as the sulphureous vapours decrease. When the ore is by this means converted into a greyish oxide, the roasting is completed, though not entirely freed from the sulphur. In this state it is afterwards exposed to a full red heat in a covered crucible, mixed with half its weight of crude tar* tar, the carbonaceous part of which decomposes the oxide, and the pure antimony falls to the bottom. Reduction of the Ores of Arsenic. The arsenic of medicine and the arts is chiefly procured during the process of roasting the ores of tin and cobalt, for the purpose of ridding them of impurities, amongst which arsenic is one. During this process the arsenic is sublimed in the form of yellow or yellowish white crystals, which are very minute and sometimes closely aggregated. Arsenic so obtained is in the state of an oxide, but very impure, and in orider to free it of impurities, it is twice washed or torrefied ; it is. then sublimed. The subliming vessels used in Bohemia are strong square boxes of cast iron, furnished with conical heads of the same material, closely luted to them with clay. These are disposed in a large brick area, heated by the flues of two furnaces placed a little below them. When red hot the impure arsenic is put into the boxes by 15 pounds at a time, where it melts ? and in about an hour it begins to sublime into the conical heads. When no more rises, 15 Ibs. more are put into the same vessel, and treated as before ; and this successive addition is continued until about 150 Ibs. of arsenic have been used to each vessel, the sublimation of which lasts about twelve hours. When cold, the workmen take oft" the 238 Reduction of Ores Cobalt. conical head, and carry it with its contents to another place, where they break off with hammers the sublimed arsenic, separating any impurity for a second operation. It is still in the state of an oxide, and in its purest form appears as a beautiful white, sonorous, vitriform mass, very brittle, and easily reduced to powder : when recently pre- pared it is considerably transparent, but becomes opake by keeping. From this pure oxide the metal itself may be obtained pure, by heating it with any carbonaceous matter, but in a metallic state it is even more volatile than when in a state of oxide, on the application of heat ; it is even the most volatile of the metals : it readily tarnishes by ex-< posure to air, but may be kept under water unaltered. .Reduction of the Ores of Cobalt. The ores of Cobalt are abundant in certain parts of the European continent, but are comparatively scarce in Britain. As a metal, cobalt is not employed in the arts, but is very valuable in the state of an oxide, to give various shades of blue to porcelain and glass. The blue colour of this oxide is so very intense, that it is found convenient to mix it with a proportion of verifiable earth, in which state it appears as a brown gritty powder called zaffre^ but when melted, as a glass of intense blue colour ; this when ground and sifted, forms the smalt of the shops. The following method of reducing the ores of cobalt, and of preparing zaffre and smalt, is practised in the large way at Schneeberg in Missnia, affording a very lucrative trade to the Saxons, The cobalt ore is put on the hearth of a furnace like a baker's oven, so constructed that the flame of wood is reverberated on all sides over the surface, and soon heats it red-hot. A very dense arsenical vapour then begins to be given out, which is conveyed through a very long hori- zontal wooden square trough or chimney, sometimes as much as a hundred fathoms in length, where the arsenic is chiefly condensed, though Kunckel remarks that notwith* standing the enormous length of chimney, some of the Reduction of Ores Cobalt. 239 vapours still escape through the further opening. The cobalt ore is calcined for some hours till it scarcely emits any more vapours, after which it is ground to powder, calcined a second time, again ground and passed through a very fine sieve. This powder is then mixed with two parts of powdered flint or quartz, moistened and put in barrels, where it grows excessively hard. This forms the zajfre in the state in which it is exported. The real reason of adding the flints appears to be for some purposes of con- cealment, the exportation of the simple calcined oxide being forbidden under heavy penalties. Smalt, sometimes also called zaffre, and when finely powdered, azure blue, is a very deep blue glass, made of the calcined ore of cobalt and some vitrifiable ingredients, which is used as a colouring matter for a variety of pur- poses. The proportion of the vitrifiable basis to the cobalt depends on the estimated goodness of the latter and the result of small trials. On an average, equal parts of the calcined cobalt ore, of potash, and of ground flints are taken. These are first fritted and then made into glass, in pots similar to those of the glass-houses, requiring from 8 to 12 hours of fusion. When the blue glass is perfect, it is taken out with iron ladles and dropped into cold water to crack it in every direction and make it more easily reducible to powder, which is afterwards performed in a mill made of very hard stone inclosed in a wooden case. At the bottom of the glass-pots a quantity of regulus of bismuth is always found, (the ores of bismuth and cobalt being naturally mixed) and above it is a mixed alloy of arsenic, iron, and copper. The grinding the blue glass is a work of labour and some difficulty. Several degrees of fineness are prepared by means of grinding or washing. These are all known by the general term of smalt, or, when in very fine powder, azure. The term azure however is also applied to lapis lazuli blue, a totally different substance. As a colouring matter smalt is very valuable, both on account of the fine intense blue which it produces, and for 240 Of Salt Deposits. its comparative cheapness, and because it is not altered by any heat. In this last respect it is superior to lapis lazuli, the colour of which is entirely and permanently destroyed in a red-heat, but smalt will not mix with oil colours, and therefore can only be very partially used. Smalt is used when mixed with starch to give a slight blue to linen, or rather to correct the tendency to 'yellow which linen acquires when worn. Zaffre is prepared also in Bohemia, Wirtemberg, Silesia, Lorrain, and some other parts of the continent, but the Saxon is preferred, and yields to the proprietors an annual revenue of 200,000 crowns. OF SALT DEPOSITS. It was stated on a previous evening that deposits of salt are principally found amongst secondary rocks. Salt is considered to belong to the New Red Sandstone^ being chiefly found in beds lying in, or connected with it, as is the case in our own and other countries. Clay, sandstone, and gypsum, almost invariably accom- pany rock salt, either above or below it \ sometimes both above and below it. The countries in which large deposits of salt are found; are for the most part approaching to flat ; they do not often exceed that elevation which is termed hilly ; though occa- sionally they are discovered at the feet of elevated moun- tains, as the Alps, the Vosges, the Pyrenees, and the Carpathian mountains. In Germany, but few instances of the rock salt for- mation occur, and none has hitherto been discovered in France ; but in both countries, especially the former, brine springs are found in considerable abundance. It is said that an uncommonly great deposition of it may be traced with little interruption from the Black Sea nearly to the Alps. It abounds in Spain ; at Cardonna, in Catalonia, is Of Salt Deposits. 241 a mountain of rock salt about 550 feet high above the sur- rounding soil, and about 16,000 feet in circumference, without bed or crevice ; but neither its depth nor the rock on which it rests, are known ; at Poza, near Burgos, the mines of rock salt are remarkably situated ; being in an immense crater; in which pumice and puzzuolana are also found. It is not very common in Russia or generally in northern countries ; none has yet been discovered in Nor- way. Nevertheless there are said to be two whole moun- tains in Astracan entirely composed of it. It is abundant in Persia; the isle of Ormus in the Persian Gulf almost wholly consists of rock salt. Whole mountains of it also occur in Tunis and Algiers, in Africa. It is found in New South Wales ; and not long since a mountain of salt of an immense height was discovered near the Missouri river in America, eighty miles long and forty-five miles wide, the surface of whicfy is barely covered with earth ; neither tree nor shrub is growing upon it. But many countries are nearly without salt. At Delhi and Agra, the capitals of Hindustan, its price is 2s. 6d. per pound : and it is said to be so scarce in the interior of that country, west of Thibet, that the natives use cakes of salt, sealed up and bearing the stamp of their prince, as money. According to Bruce, it passes as money in Abyssinia. It is found in New Holland ; is very abundant in the plains of the Mississippi in North America ; there is a salt lake in the valley of Mexico, and Humboldt speaks of mountains of rock salt in the vast plains at the north-east of New Mexico. Perhaps the most extensive deposition of rock salt in the world occurs in Wielitska, near Cracow in Poland, at the northern extremity of a branch of the Carpathian mounT tains. It has been worked as a mine since the year 1251, and its excavations are said to extend more than a league from east to west. The salt is of an iron grey colour, in which are found cubes of a pure white. This mine was visited by our countryman Wraxall ; 242 Of Salt Deposits. from whose account of it some idea of its vastness may be gathered. He says, ^ After being let down by a rope two hundred and thirty feet, our conductors led us through galleries, which for loftiness and breadth seemed rather to resemble the avenues to some subterraneous palace, than passages cut in a mine : they were perfectly dry in every part, and terminated in two chapels composed entirely of salt, hewn out of the solid mass. The images which adorned the altars, as well as the pillars and ornaments, were all of the same transparent material ; the points and spars of which, reflecting the rays of light from the lamps which the guides held in their hands, produced an effect equally novel and beautiful. Descending lower into the earth by means of ladders, I found myself in an immense hall or cavern of salt, many hundred feet in length, breadth, and dimensions, the floor and sides of which were cut with exact regularity. One thousand persons might dine in it without inconvenience, and the eye in vain attempted to define or trace its limits. Nothing could be more sublime than this vast subterraneous apartment, illuminated by flambeaux, which faintly discovered its prodigious magni- tude, and left the imagination at liberty to enlarge it inde- finitely." Hitherto w T e have not mentioned the deposits of salt, and the salt or brine springs, which are so abundantly found in our own country. A description of some of these is my principal object. The chief are those of Droitwich in Worcestershire, and of Northwich in Cheshire, which are the most productive. I proceed first to the brine springs at Droitwich. These springs are said to be mentioned in the Domesday Survey, which was finished in 1087. The prevailing rock around Droitwich t is a brownish + Salt was an object of taxation at a very early period in this coun- try. Ancus Martius, 640 years before our era, * Salinarum vectigal instituit.' This tribute was continued on the Britons when our isle was Of Suit Deposits. 213 red sandstone, considered to be of the formation termed by English Geologists the new red sandstone. At this place the brine springs are four in number, a: I situated within a square furlong ; and as no new pit has been sunk within the last thirty years, we have not a very accurate account of the strata through which they passed, before they arrived at the brine. From the account given by Dr. Nash in his history of Worcestershire, we gather these facts : that four pits were variously sunk through from thirty to fifty-five feet of soil and rock, when they arrived at a stratum of gypsum varying from 102 to 150 feet in thickness ; on passing through this, they suddenly arrived at the salt brine, which, immediately on their ar- riving at it, rose quickly to the surface and overflowed. In each of the pits the brine was twenty-two inches in depth : in each also it was ascertained that it was imme- diately resting on a body of rock salt. Into this rock salt they bored two feet and a half without passing through it; the brine being their object. From this account, the principal information we gather, is, that the water of these springs is impregnated with salt by a body of rock salt ; and that, as the brine rises perhaps 180 feet to the surface and overflows, the sourse of these springs must be situated in much higher ground than that possessed by the Romans, who worked the Droitwich mines, and who made salt a part of the pay of their soldiers' salarium or salary. Hence the custom at the Eton Montem of asking for salt. The ancient mode of making salt, and which even now I believe is practised in Germany, was to fling the brine on burning wood, by which means the water was evaporated, and the salt was left adhering to the ashes. The Saxons, according to their ideas of liberty, divided the salina between the king, the nobles, and the freemen. Of the salt works at Nantwich, eight were the joint property of the king and Earl Edwin. The king had two-thirds of the profits, the earl one-third : Edwin had also a work near his manor of Aghton, which yielded sufficient salt for the consumption of his household. If the salt of this work was sold, the king was to have a tax of two pence upon it, and the earl one penny. 244 Of Salt Deposits. in which the pits are sunk. The brine is perfectly limpid, and contains about one-third its weight of salt.* The quantity of brine which issues from these four pits is immense. That which is used) bears but a small pro- portion to that which runs to waste : nevertheless, the quantity of salt annually made from these four pits is about 16,000 tons; two^thirds of which are consumed in Eng- land, and, until lately, paid a duty of about 320,000 per annum. The market price of the salt was formerly 31 per ton, 30 of which was duty. We come now to the great beds of rock salt at North- wich in Cheshire. These beds are known to extend one mile and a half, north-east and south-west, and are upwards of three quar- ters of a mile wide : there are two beds lying one beneath the other. The strata above the upper bed consist of gypsum, and of alternating beds of variously coloured marl, red, blue, and brown ; some of them are so porous as that it has been ascertained that 360 gallons of water rise through them in a minute ; a circumstance that greatly impedes the sinking of the pits. It is remarkable, but it is well ascertained, that the various strata above the upper bed of rock salt contain no marine fossils. These strata are from 105 to 120 feet thick ; they repose on the first bed of salt which is from 60 to 90 feet thick : between the first and second beds of salt lies a stratum of indurated marl, 36 to 40 feet in thickness. So that the surface of the second or lower bed of rock salt is about 220 feet from the surface of the land. Into this second bed of salt they have sunk about 150 feet, without having found the bottom of it. The salt of these mines is for the most part of a reddish * A pint of the brine of the Droitwich springs contains about 2248 grains of muriate of soda, 38 sulphate of lime, 42 sulphate of soda, 2 muriate of magnesia. Of Salt Deposits. 245 hue, arising from some admixture of iron ; and it is gene- rally so hard, that the blast by gunpowder is employed in breaking it down. The lower part of -the lower bed is the purest; and in it there are considerable cavities about 16 feet in height; in which, occasionally, pillars of salt are left, six or eight yards square, which form the supports of the roof. The cavities are worked into aisles or streets ; which, when illuminated by candles fixed on the sides of the rock, give a brilliancy of effect that is singularly strik- ing ; and, it is said, almost appear to realize the magic palaces of the eastern poets. Some idea of the vast magnitude of the Cheshire salt de- posits may be formed, when it is mentioned that its many mines yield 16,000 tons for home consumption annually, and that 140,000 tons more are annually exported from Liverpool. We come now to the consideration of the means by which these vast formations of rock salt were deposited. It must be obvious that all that can be said will amount to no more than theory : a theory which presents some objec- tions, while its basis seems reasonable in itself The Cheshire salt beds occupy vallies surrounded by hills of secondary formation ; and the upper surface of the bed of salt is about 40 feet below low-water mark at Liver- pool. The numerous facts already adduced, have led us decidedly to adopt the belief that the sea must have stood at an elevation greatly above the general level of the earth. Is it not therefore reasonable to presume that these beds of salt were deposited by the sea; and that the beds of clay lying between and above them resulted from the ruin of rocks ? The arguments in support of this theory are, That the upper surface of these deposits of salt^ is 40 feet under low-water mark. That, in the beds of marl, it is not unusual to find frag- ments of the older rocks ; such as large portions of granite, shewing marks of attrition. 246 Of the Deluge. That these deposits of rock salt contain some salts, as the sulphate of soda, which also is found in the waters of the ocean. The principal argument against this theory is, that no sea shells or weeds are found above or below these beds. But perhaps we ought to take into consideration that there are beds of salt near Salzburg in Austria, which are stated by Von Buch to be 2975 feet above the sea ; and that the salt mines in the Tyrol are yet higher. In the Cordilleras of New Grenada are immense beds of rock salt at the height of 8400 feet above the sea level. We have however heretofore produced evidence that the sea has been at much greater elevation than this ; and that almost entire strata of sea shells are found at such eleva- tions. OF THE DELUGE. The traditions recorded by many persons and nations perfectly agree with the writings of Moses, and with the researches of geologists, in regard to the actual state of the surface of the globe, in this, that it has suffered a great catastrophe by water. It is alluded to by Berosus in the time of Alexander ; by Plato ; by the Hindus ; who, ac- cording to Sir William Jones, mention it in one of their sacred books, or vedas, nearly in the same terms, and refer it to nearly the same period as ]\Ioses ; and in the records of the Chinese philosopher Confucius, there is an allusion in the following terms ; ' Having raised himself to heaven, Yao bathed the feet even of the highest mountains, covered the less elevated hills, and rendered the plains impassable :' allusions to the deluge are also said to be involved in the astronomical calculations of the Chaldeans. It is remarked by Cuvier that mere chance could not give so striking a resemblance between the traditions of the Assyrians, the Hindus and the Chinese ; who moreover attribute the origin of their respective monarchies to the same period of about OJ the Deluge. 247 4000 years back. The ideas of these three nations, who have so few features of resemblance, or rather, who are so entirely dissimilar in language, religion and laws, could not have so exactly agreed on this point, if it had not been founded in truth. Other and remarkable traditional evi- dence may be adduced. Acosta, in his history of the Indies, says that the Mexicans make particular mention of a deluge by which all men were drowned ; and Dr. Watson, in one of his sermons, records a reply given by an inhabitant of Otaheite to one of our circumnavigators, to a question regarding their origin ; that 4 a long time ago, the earth was dragged through the sea; and their island, being broken oif, was preserved.' If it be true, as stated by Don Ulloa, that during his travels in Peru he found shells on a mountain more than 14,000 feet above the level of the sea, it affords presump- tive evidence that the sea must have attained that elevation; which is nearly equal to two-thirds the height of the most elevated points of land : and if it arose to so great a height, there seems no reason for assuming that as the limit ; we may reasonably thence infer that it covered the tops of the highest mountains. Deposits of marine plants and animals have been found in the interior of the European and Asiatic continents, frequently in considerable abundance. In Corsica are found the remains of an animal exclusively belonging to Siberia. In the year 1771 the carcase of a rhinoceros, an inhabitant of the torrid zone, was found on the banks of the Vilhoui. The bones of the mammoth, which is a species of the ele- phant, are found in three of the four quarters of the globe; and those both of the African and Asiatic elephant, have been found in many places in England : they occur like- wise in Italy, France, Germany and Sweden ; and in the elevated plains of Peru and Quito in South America. It is worthy of remark, that, although in some instances, the carcases of the animals occurred nearly whole, entire skele- tons are seldom found, but mostly separate bones, widely dispersed: and it is said that between the countries now 248 Of the Deluge. inhabited by these animals, and some of those in which their bones have been discovered, there are chains of moun- tains exceeding 9000 feet in elevation. v The remains of the animals which are found in the newest of the deposits of gravel, sand, and brick earth, have been found in the countries above cited under circum- stances so nearly similar, as themselves to induce the be- lief that the earth has suffered by a universal inundation. It is the opinion of Cuvier that if there be any one fact established by geological investigations, it is this that the earth has been recently overwhelmed by the waters of a transient deluge. One of the most decisive proofs that a comparatively recent deluge has swept over the surface of the earth is, that the fragments of the oldest and of the newest deposits lie together in the same accumulation of diluvium ; for hence it must follow that it happened after the deposition of the newest beds. If however we were to be asked for proofs that mighty currents of water had swept over the surface of the earth, we need not stray beyond our own island for the most manifest evidence. In the middle tiacts of England, and particularly around Litchfield, vast accumulations of a species of gravel are to be observed, including fragments of almost every rock in our series between chalk and granite. The gravel (observes Professor Buckland) accumulated in the midland counties of England is considered by Mr. Conybeare to be a subject worthy of much more attention than it has hitherto received. These accumulations have been observed by him to extend over the plains that lie beneath the north-west escarpment of the great oolite chain, and also over the low tract between these hills and the north-west escarpment of the chalk of Bucks, Herts, and Bedfordshire ; but they are more particularly abundant in the former position, where extending many fathoms in depth, they often -ifectually conceal the subjacent strata, and sometimes by their acervation constitute decided hills. Of the Deluge. 249 Tracts of this description are particularly abundant on the borders of Rutland, Warwick and Leicestershires. From Houghton on the Hill near Leicester, to Braunston near Daventry, proceeding by Market Harborough and Lutter- worth, the traveller passes over a continuous bed of gravel for about forty miles ; near Hinckley, great depositions of gravel, probably connected with this mass, are found, and afford pebbles containing specimens of the organic remains of most of the secondary strata in England ; this deposition may probably be traced continuously to that of Shipston on Stour, most of the hillocks scattered over the lias and red marl tract between Southam and Shipston being crowned with this gravel. These accumulations of pebbles, promiscuously heaped together, are composed of the wreck of rocks of the most distant ages, which exist in their native state only in dis- tant quarters of the island ; flints from the chalk formation, accompanied by rounded masses of hard chalk and frag- ments of the different oolite rocks, seem however decidedly predominant in Leicestershire ; and next to these in quan- tity, are the granular quartz rock pebbles resembling those from the Lie key, while others are of white quartz (apparently derived from veins) and dark coloured hard flinty-slate. It would not however be difficult in many places, as for instance on the west of Market Harborough, and Jn the valley of Shipston on Stour, to form almost a complete geological series of English rocks from among these rounded fragments^ which often occur in boulders of very consider- able size. The immense quantities of fragments of chalk flints scat- tered in this gravel at such a distance from the present limits of the chalk, is a very observable circumstance, and seems decisively to indicate that this formation must once have occupied a much wider space than it does at present. Near Syrwell, six miles north-east of Northampton, on the oolite formation, are some fields as thickly strewed over with fragments of pure white chalk, as the surface of stony arable land is usually with the substance of the subjacent 2 i 250 Of the Deluge. rock. Even as far as Derbyshire, chalk flints are commonly found dispersed over the surface of the country. The accumulations of gravel on the low grounds between the oolite and chalk ridges along the valley of Buckingham and Bedford, and skirting the lower or south-east slope of the great oolite range, are almost exclusively composed of fragments of oolite and chalk ; older pebbles being there very sparingly intermixed. Examples of this may particu- larly be seen at Wittlebury Forest in Northamptonshire and near Buckingham. The above observations on this subject, by Mr. Conybeare, are in perfect harmony with my own in other parts of England.' It is not however pretended that all beds of gravel are the consequences of the great deluge. Long antecedent to that event, there exist the most manifest proofs that the older rocky masses constituting what has been termed the frame-work of the earth, must have suffered by the action of water upon them : for if we refer back to the descrip- tions of the old and new red sandstones as constituents of the series of our rocks, we shall be convinced that they are composed of the debris or ruin of previously existing rocks ; of which the fragments have been so rounded by long continued diluvial action, as to resemble in form the shingle on the sea shore. These and similar deposits, from their frequent want of solidity, may possibly have suffered by the waters of this universal but transient deluge, and portions of them, having been carried off by the retiring currents, may have occasioned in some instances those accumulations which are perceptible in every quarter of the world. It is however perfectly incredible that either the duration or the violence of the waters of the universal deluge should have been sufficiently great and extended to have rounded quartzose or flinty masses. The form of the individual mass or fragment could scarcely have been af- fected by it, though it may in some degree have altered the position and form of the accumulation. Hence pebbles that are completely rounded have been termed antediluvian^ while those which are still more or less angular are termed Of the Deluge. 251 diluvian, and they are sometimes found intermingled in the same deposit ; and hence Professor Buckland proposes to restrict the term diluvium, to the superficial gravel beds of the last deluge ; the term alluvium being confined to the ruin occasioned by rapid rivers, mountain torrents, the bursting of Alpine lakes, &c. In the 5th volume of the Transactions of the Geological Society there is an interesting and ingenious communica- tion by Professor Buckland on the quartz rock of the Lickey Hill, in Worcestershire, in which he shews that pebbles perfectly resembling that rock, which in its natural bed is so full of crevices that it easily separates into small angular masses, are to be traced from their original site, through an opening in the hills of the oolite escarpment and along the valley of the Thames and Evenlode, to very near London, their quantity decreasing with their distance from their source ; and hence he infers the direction in which in that part of the country, the retreat of the waters took place. It is indeed highly probable that c the order of things immediately preceding the universal deluge closely resem- bled their present order, and was suddenly interrupted by a general flood which swept away the quadrupeds, but was of short duration ;- animals and plants similar to those that had perished once more adorned its surface, and na- ture again submitted to that regular system of laws, which has continued uninterruptedly to the present day.' The manner in which this deluge was accomplished, is a problem that has long occupied the imaginations of phi- losophers and naturalists. The question is this : since the tops of the highest moun-r tains, which are about five miles above the present level of the sea, were covered with water ; whence could be derived a sufficient quantity to surround, to the depth of five miles, a globe 25,000 miles in circumference. It is evident that in order to accomplish this, the rain of forty days and nights was not sufficient; for the context 2 i 2 252 Of the Deluge. says that c all the fountains of the great deep were broken up.' What precisely is meant by the great deep and where it was situated, still continues to be problematical. Attempts at its explanation have caused the fabrication of at least fifty theories of the Earth, not one of which is satisfactory. Some of these theories were briefly recounted on a former evening, as being more or less connected with the creation of the world. Burnet imagined that before the deluge, the Earth was a mere crust, containing a vast abyss of waters ; which issuing, deluged the Earth, forming mountains of the broken crust. Whiston supposed the deluge to have been occasioned by a comet. But a bare recital of hypotheses so gratuitoui would scarcely be amusing ; for in the general, there is so little agreement between them and the known phenomena of nature, as resulting from those laws which in point of fact constitute nature^ that they are no longer deemed worthy of a place in a rational mind. Other theorists, however, bent upon a more reasonable philosophy, have looked into nature for a solution of this interesting ques- tion. Kirwan has assumed that, in addition to the rain of forty days and nights, a prodigious rising took place in the waters of the great Southern Ocean, which, he sets out with saying, is the greatest collection of waters on the face of the globe ; that this ocean was the great deep mentioned by Moses; and he supposes that Noah resided on its bor- ders, for otherwise he could not have seen that the great abyss was opened. He conceives that these waters were impelled northwards, with resistless impetuosity, against the continent which at that time probably united Asia with America ; tearing up and sweeping away the whole of that immense tract, with the exception of those islands which still remain. Here then is imagined a suspension of some of the laws of nature, or how could so vast a body of waters have Of the Deluge. 253 arisen from its natural level, and have torn up and swept away a whole connecting continent, by what Kirwan terms its resistless impetuosity. I do not propose to follow him through all the ramifications of his theory, but it may not be amiss to notice the apparent impossibility that the ark, or the little world within it, could have sustained the hor- rible shocks that must have been given to it by surges equal in power, and frequent enough in repetition, to cause the destruction of a continent. Others have resorted to another theory. It is known that there is at all times a passage of electric matter into the earth, or from the earth into the atmosphere ; and it is presumed that the electric fluid contained in the atmos- phere, is the agent which suspends therein, the water which rises from the earth in vapour. Now they suppose that natural causes were so influenced for the sake of producing the deluge, as that the air being divested of the electric fluid, universal and amazing tor- rents of rain fell during forty days and nights. And it is farther supposed that as the earth contained a double por- tion of electric fluid, which experiment has proved to possess the power of raising water upon and above the earth, that the waters contained in its fissures and caverns, and even whole oceans, were thereby raised so far above their natural elevations, as to cover the tops of the highest mountains. Thus has the sagacity of man (according to the present extent of his knowledge) been brought into action, in the endeavour to account for this wonderful phenomenon ; and we have seen that even those who have attempted to ex- plain it, in some sort through the agency of natural causes, have been compelled to call in aid of their theories, the miraculous intervention of the Great Author of Nature. 254 Of the Excavation of Vallies. OF THE EROSION OR EXCAVATION OF VALLIES. VALLIES may be described as being of two kinds, which may be termed Natural vallies and Excavated vallies. Natural vallies are such as may obviously be referred to original deposition, and will be best illustrated by a simple diagram, exhibiting a Section of two ranges of mountains, and of a valley between them. Let us assume a a to be two mountains, and that the hollow between them has been partially filled by regular beds, ft, c, d. For the present object it is unimportant whether we consider these mountains to be in the very form of their original deposition, or whether they have "been elevated by a force from below. The beds &, c, d, appear in the same order on the side of each mountain as in the valley between them. There is nothing like the appearance of their having suffered injury by external causes, nor can we imagine any, except such as must neces- sarily result from exposure of the surface to atmospherical action ; the whole is in the natural state. But if instead of the order manifest in the above sketch, which is not merely suppositious, because it occurs in nature, we were to observe the beds now constituting the valley, in a dif- ferent form, we should have reason to assume, even if we had no previous notion of the extensive action of deluges or inundations on the surface of the earth, that some cause or other, different to that which produced the first ; must have produced the second. Of the Excavation of tallies. 255 We now perceive a little central hill, regularly stratified, having on each side of it a valley : and we perceive that the strata, constituting the little hill, appear in the same order on the flanks of the mountains : and wheresoever this is found to be the case we should infer that the hill and neighbouring strata were once continuous, and that some cause, some violent action, had broken their con- tinuity, had worn away and carried off the materials which once filled up the now vacant space or valley on each side the central hill. Now let us assume that the three beds thus broken con- sisted of well characterized rocks, of such as would readily be recognised if they were found in masses, whether large or small, at some distance from the parent strata. If then after observing such a want of continuity, we were to find shapeless fragments of these rocks at a distance from it> should we not refer to the spot, and believe that some adequate cause must have removed them ; and if we ob- served that the angles and edges of these masses were not ^cute and sharp, we should almost necessarily infer that they had suffered injury in the transport ; but if we found them without angles or edges, and ovate or rounded, we should infer that this injury had been great, and that if the rock was hard and liable to injury only by long continued action, that they had been subjected in the transport to violent attrition against each other, and that this action had been continued during a long period of , time; and should we not immediately compare the forms of these masses with the rounded pebbles on the sea shore, and refer the con- sequences so perfectly similar in each case to the same cause, namely, violent and long continued action of isatcr 256 Of the Excavation of Vallies. upon them, causing the disappearance of the angles and edges. Now every part of the earth exhibits on its surface masses of various sizes, and in different places of every variety of rock ; some of these are large and angular, as is the case with the huge blocks of granite spread over the surface of various parts of Germany, and which have been referred to the granitic chains of northern Europe as their original position : others are small and rounded, as is the case with the gravel, so abundantly used for the repair of the roads around London, and which lies in thick and ex- tensive beds. This gravel is manifestly flint, of which the native place was in chalk, but which has suffered injury by violence on its surface ; the chalk itself being the lightest and softest, having been altogether carried away, leaving the harder and heavier flint behind. The immense quantities of fragments of chalk flints scat- tered in this gravel at such a distance from the present limits of the chalk, is a very observable circumstance, and seems decidedly to indicate that this formation must once have occupied a much wider space than it does at present. Near Syrwell, six miles north-east of Northampton, on the oolite formation, are some fields as thickly strewed over with fragments of pure white chalk, as the surface of stony arable land is usually with the substance of the subjacent rock. Even as far as Derbyshire, chalk flints are commonly found dispersed over the surface of the country. It is impossible to attribute the formation of such vallies as we are now contemplating, namely, such as are flanked on each side by similar strata, to action resembling that which is now produced by existing causes ; the little tor- rents and streams which now traverse such vallies are altogether inadequate to such an effect ; nor is it possible to believe that such streams could have transported the materials of the broken strata to such distances as they are found in the form of fragments ; nor could they have caused such an attrition as to wear away the angles and edges of the masses. Of the Excavation of Vallies. 257 In treating of the deluge, it has been shewn that vast accumulations of detritus of rocks are found in the central parts of England. Professor Buckland, in a paper inserted in the 6th volume of the Geological Transactions, has availed himself of the section presented by the cliffs on the coasts of Devon and Dorset, to shew that the vallies between the hills on these coasts are the consequences of the violent action of water, to which the surface of the earth has manifestly been sub- jected : the following very slight and imperfect sketch of a part of these cliffs will evince the probability of his con- clusions, at least in part. The first hill on the left is Peak hill, and between it and the next (Salcombe hill) lies the valley of Sidmouth. To Salcombe hill on the right succeeds Dunscombe hill, to which succeeds Comb hill, having Brandscombe cliff on the extreme right. The red marl or new red sandstone forms the base of the cliff along the whole extent, on which lies the green sand; the cap of every summit being of chalk. Hence we perceive the very great probability that the chalk and green sand were once continuous along the whole line, and that their want of continuity evidences the action of water on the strata, sufficiently violent for the excavation of the vallies now lying between the several hills ; and if evidence were wanting of the chalk and inferior strata having suffered a partial destruction, we have only to resort to the Chesil Bank connecting the Isle of Portland with the main land, of which the principal ingredients are rolled flints and pebbles of chert ; the abundance of the former in chalk, and of the latter in the green sand, are well known. It suffices to observe natural phaenomena of this descrip- tion to be convinced that the original forms of the strata 2 K 258 Of the Excavation of tallies. have been greatly modified superficially by violent inun- dations, and that these and similar vallies are the conse- quences of such action. How far the softer rocks composing the present surface of England may have been modified by such causes ? it is impossible to imagine ; in tracing however the abrupt escarpment of the chalk, and of the oolite beds, running from the north through the midland counties to the south- western shores, and comparing the hardness of these sub- stances with that of the sandy strata on the west at the base of the one, and of the marly strata at the base of the other^ we are induced to -infer that such causes may have pro- duced these abruptnesses of the harder beds ; and hence it \s impossible to decide how much further on the west the chalk and oolites formerly extended. One argument for the comparatively recent Excavation of such vallies is, that on the summits of the neighbouring hills are often found pebbles and rounded masses of the older rocks, whicli in all probability must have been washed and left there previously to the excavation of the vallies ; and hence Professor Buckland is of opinion that the valley of the Thames, which near Oxford is bounded by high and even conical hills, on the summits of which rounded masses of the old rocks are found, is the consequence of the de- nuding agency of the subsiding waters of the most recent deluge that affected the earth. That an universal deluge once prevailed over the surface of the earth we have the most convincing proofs ; it is nevertheless difficult of conception that a deluge so tran- sient^ and in regard to which there seems no evidence on record to prove that it either began or receded with violence, should in any important degree have tended to alter the form of the earth's surface. Hence it behoves us to pause before we yield implicit confidence to the proposition that the excavation of these and similar vallies was effected by the universal deluge more especially since there exists at this moment, a sort of fashion in referring to its action much that might with Of Volcanos. 259 equal propriety be assigned to such irruptions of the sea as it is acknowledged must have taken place antecedently and which must in all probability have been of longer duration and more violent in their effects. OF VOLCANOS. On Volcanos so much has been written, both of fact and of theory, that it is extremely difficult to select and compress into a narrow compass the most interesting details belonging to the subject. Volcanos are scattered over the globe in every latitude^ sometimes singly, more often in groups, or forming a con- nected line or chain, rarely in the interior of a continent, usually near the borders of the ocean, or rising in a moun- tainous form from its depths. They occur in groups in the Canaries, Cape de Verd, and other islands ; the most remarkable instance of their occurrence in an almost connected line, exists along the w est coast of the Americas ; two lines traverse France. These are supposed to be seated above enormous crevices, produced by volcanic action. Volcanos are found at almost every elevation between the level of the sea and that of Cotopaxi in South America, which rises 18,880 feet above it. The number now, or occasionally in activity, is stated at about 200, t the greater proportion of them being on the American continent ; but no estimate has hitherto been made of the number that have existed in different parts of the gldbe, and indeed in almost every country, for there is scarcely one in which masses more or less decidedly vol- canic are not visible. + At the end of a work entitled " Considerations on Volcanos," &c. by G. P. Scrope, Esq. there is a map of the volcanos now in existence. 2 K 2 260 Of Vokanos. The forms of volcanic mountains are perpetually altering, of which an instance may be cited in regard to a colossal cone called the Peak in the island of Timor, one of the Moluccas. The whole mountain was previous to 1638 continually active, and so lofty that its light is said to have been visible 300 miles ; but in that year the whole moun- tain was blown up, and replaced by a concavity now con- taining a lake. The quantity of matter thrown up in various' forms by a single volcano is sometimes inconceivably great, as will become obvious on considering the facts relative to that of Jorullo, which will presently be quoted. Dr. Daubenyt observes that the covering of three entire cities under a heap of ashes from 60 to 112 feet in depth, would seem an effort almost too gigantic for the powers of this single mountain (Vesuvius), if we were not aware of the vast depth at which volcanic operations are going on, and the immense extent to which their influence may therefore be supposed to reach. It has been calculated indeed that the masses ejected at different times from Vesuvius vastly ex- ceed the whole bulk of the mountain; which however seems to undergo no diminution ; for the falling in of its cone at one period appears to be balanced by the accumulation of ashes at another. Alternations of beds of lava and tuff compose most vol- canic mountains ; and those in the instance of Vesuvius are every where inclined at an angle of 30 degrees, and rise towards the cone. Of some volcanos, the eruptions are incessant ; as that of Stromboli, which is believed not to have intermitted during the last 2000 years ; of others again, the periods of tranquillity, though uncertain, are not of very long dura- tion, as is the case with Vesuvius ; others again, remain for a century, or more, perfectly tranquil ; the eruption of jEtna in 1533, occurred after a quiescence of nearly a cen- tury, and lasted two years with terrific violence. t In his work entitled " A Description of active and extinct Vol- canos," &c. Of Volcanos. 261 According to Dolomieu the crater of Strombbli does not exceed fifty paces in diameter. This volcano is mentioned by Pliny; and it is said that from time immemorial, its eruptions have taken place about every seven or eight mi- nutes. c I saw it dart,' says Dolomieu, * during the night, at regular intervals of seven or eight minutes, ignited stones, "which rose to the height of more than 100 feet, forming radii a little diverging ; but of which the greater part fell into the crater, while others rolled even to the sea. Each explosion was accompanied by a burst of red flame. The stones ejected are of a lively red, and sparkle, having the effect of artificial fire-works. The approach of the erup- tion is not announced by any noise or dull murmur in the interior of the mountain.' The most extraordinary phenomena attending volcanos are the streams of melted matter, called lava, which flow from their craters. The crater or cup-shaped cavity is usually found on the summit of the mountain, but this does not always happen to be their actual position ; for in the eruption of ^Etna in 1536, twelve different motiths opened successively one below another, on the same line or jftssure^ each producing lava, while the central crater vomited va- pour and scorias. This circumstance of their being on the same line or fissure, is not only noticed in regard to single volcanos, but by the best observers is considered often to belong to volcanos in the aggregate, as has already been noticed, and as is readily observable on casting the eye over the map mentioned in a preceding note^ We shall presently turn our attention to the nature of lava but it may previously be observed that besides those substances which have issued in streams from volcanos, and which collectively, though of different aspects, may be termed lava, there are certain rocks still differing from the general varieties of lava, and which are termed trap rocks. These now are considered almost universally to be of vol- canic origin, but for the most part older than lava. Volcanic rocks have certainly been formed under very different circumstances. Some, and perhaps the greater 262 Of Volcanos. part, have issued from the volcano in the open air; such are ordinary streams of lava; others have certainly beer* raised from below the bottom of the ocean ; the former have cooled under ordinary circumstances ; the latter how- ever have cooled and become solid under the body of water above them, and therefore under pressure; and this is be- lieved to be the cause why these latter rocks are more highly crystalline than those which become cool in th open air : and for the sake of distinguishing these different kinds, Mr. Scrope has divided volcanos into sub 'aerial and sub-aqueous. It is also certain that volcanos have been in activity at very different periods of time. Dr. Daubeny has divided volcanos into ante-diluvial and post-diluvial : for it is ma- nifest that some streams of lava have by natural causes been divided, and probably at the time at which the vallies were excavated, and the surface of the earth was reduced to its present state. These are in some instances at least con- sidered to be contemporaneous with the older rocks, and therefore tHeir characters appear to be modified by pres- sure, as in the trap rocks : others were deposited during the deposition of the tertiary beds ; as in the instance of the trachytes and basalts of the Seven Mountains near Bonn 3 and several other chains in the same neighbourhood ; others again manifestly flowed since that period, for they have taken their course down and across vallies, and have turned streams, or stopped their course, forming lakes ; such are the lavas of the Eyfel between the Rhine and the Nether- lands, and those of Auvergne. Near Puy en Velay in France a trap tuff composed of fragments of scoriform lava and basalt, with the debris of other rocks, all cemented together by sand and wacke, rests on rocks of the tertiary formation, and is covered by diluvium. In some parts of Auvergne a volcanic breccia rests on strata containing freshwater shells and bones of mammalia similar to those of the Paris basin : hence this breccia must have resulted from an eruption which took place Of Volcanos. 263 tiftcr the deposition of the tertiary rocks, though anterior to the time at which the vallies were excavated. The gaseous exhalations most commonly given off from Vesuvius appear to be sulphurous and muriatic acid gases, the former chiefly produced during a period of calm, the latter at and immediately subsequent to, an eruption. Ni- trogen gas has likewise been detected, and much aqueous vapour is generally present. The latter indeed often con- stitutes the sole product of those Fumaroles that surround the external slop of the crater, when the mountain is in a tranquil state. Fatal Mojfetes, or exhalations of noxious gas, are given out from crevices in all parts of the mountain : and are supposed to consist chiefly of carbonic acid gas. The gases which arise through the crevices of lava during consolidation, are principally carbonic acid, azote, and sul- phuretted hydrogen. From some of the volcanos of America have issued streams of boiling water mixed with mud, and sometimes including such multitudes of a peculiar small Ash, as in some instances to taint the air : these are by Humboldt supposed to pro- ceed from lakes in the interior of such mountains, adapted for the abode of the fish, but above the reach of the vol- canic action which.may be assumed long to have existed below the base of the mountain. The streams of lava which burst with prodigious vehe- mence from a volcano differ greatly in respect of dimen- sion. One is recorded as having issued from ./Etna, which is four or five miles broad, 15 miles long, and 50 to 100 feet thick. The rate at which they flow of course greatly de- pends on the nature of the ground over which they pass, but they often continue to move forward at a slow pace for a long time after their escape from the volcano. In the year 1819, on the banks of ^Etna, Mr. Scrope perceived a current yet progressing at the rate of about a yard per day, which had been emitted nine months before, and he ob- serves that other currents from the same volcano are cited 264 Of Volcanos. by Ferrara and Dolomieu as still moving on ten years after emission. Lava is emitted at a brilliant white heat in a state of liquidity not exceeding that of honey. The surface con- solidates immediately, emitting vapour, and at the same time cracking in all directions; the colour soon passes through red to black. The term lava is sometimes used as a generic term, com- prehending all the varieties described under the different names of lava, trachyte, &c. It is said that any kind of lava reduced to complete fusion artificially and then ex- posed, hardens into glass ; whereas, though it is propelled from the volcano in a liquid state, and consolidated by the same circumstance, it generally assumes on cooling some degree of a stony or crystalline texture. Hence, it has been argued that the natural liquefaction of the lava is not of the same kind as that produced artificially ; and hence it has been assumed that the vapours and gases which so abundantly escape from a current of lava, may have some effect in modifying the natural liquefaction. Generally speaking, the nature of lava is badly under- stood, because either the parts are so minute as not to be separately observable, or it appears to be a homogeneous mass. It is however nearly certain that felspar and augite are the principal ingredients, and that the colour of the lava is dependent on the prevalence of the one or the other. The minerals which are discoverable as entering in no- table proportion into the composition of volcanic masses are very few ; as felspar, compact felspar, augite, horn" blende, oxidulous iron, olimn, mica, leucite ; other minerals are found in their cavities, but these can scarcely be said to enter into the composition of the rock. Of all the com- ponents felspar or compact felspar is the most abundant ; felspar, when it retains its crystalline form, is generally translucent, colourless, and is traversed by cracks in every direction. The composition of the greater proportion of lavas can only be conjectured by analogy, their parts being Of Volcanos. 265 too small for actual determination. It is remarkable, that quartz, so extremely abundant in rocks of which the com- position is not suspected to be of volcanic origin, is scarcely ever found in such as are decidedly volcanic. It is remarked by D'Aubuisson that volcanic masses take different appearances according to the different circum- stances under which they cool ; we find them under the aspect of stone, of glass, of pumice, and of scoria; and he observes that when they cool rapidly (according to the experiments of Watt and Hall), they become glass, or a species of enamel ; when the cooling is gradual, but of a certain degree of rapidity, spheroidal semivitreous masses, are formed in the middle of the liquid mass, but these have sometimes a stony aspect ; these he terms devitrified ; these globules sometimes constitute the whole mass. When the cooling is very slow, the mass becomes entirely stony, sometimes with a crystalline grain ; but when a torrent of fused matter runs in the open air, elastic fluids are disen- gaged, and these raise and tear in pieces the surface, and fill with cavities the parts of the mass immediately be- neath it ; and hence as the cooling is rapid, the fibres, and the linings of the cavities, are vitreous or semivitreous, and the mass resembles (near the surface) scoria, or pumice ; but as the cooling of the interior must of necessity be a very slow process, it has almost always a stony aspect, being however sometimes filled with pores or minute cavi- ties imperceptible to the naked eye. The lava of Volvic in Auvergne, for an extent of eight leagues north and south, is described as consisting chiefly of fused felspar, containing no augite, but abundance of specular iron ; that of Puy de la Vache is scoriaceous, that of Puy Pariou consists of loose masses of slaggy lava; while the summit of Puy Graveniere consists of cinders ; that of Puy de Dome, which attains the height of 4000 feet, is a species of trachyte t (fused felspar, Domite), while the t Dr. Daubeny, p. 7, remarks that trachyte, even when of the colour of basalt, melts before the blowpipe into a white enamel, whilst basalt retains its original colour after being fused. 2 L 266 Of Volcanos. summit of Puy Chopino exhibits masses of granite, both unaltered and altered by heat. The volcanos of Auvergne are post diluvian, and many of them are seated in granite. The principal rocks of the elevated ridge separating the Puy from the Vivarais are trachyte and clinkstone. Dr. Daubeny says, that wherever the lava of Vesuvius has cooled under circumstances favorable to the develope- ment of crystalline arrangement, the result appears to have been a granular mixture of felspar, leucite, augite, and titaniferous iron. The older lavas of Vesuvius consist of leucite and augite. Mr. Scrope observes that the lava of Stromboli consists solely of augite ; that of Bourbon solely of felspar. Several substances are found in the crevices of lava, as oligiste iron, hornblende, augite, and other minerals ; these it can scarcely be doubted have been formed, if not by a subsequent infiltration of water, by a species of sublima- tion ; but the best observers do not yet seem to have de- cided the point as to whether the crystals of augite some- times occurring in the solid mass of the lava, were formed after its fusion, or existed previously thereto. The following sketch of the circumstances which uni- versally appear to characterize great eruptions is extracted from the work of Mr. Scrope. ' They are usually preceded by earthquakes f more or less violent, extensive, frequent, and prolonged ; which are obviously caused by the efforts of the lava, swelling on all sides from the encreasing elasticity of the aeriform fluids it contains, to force a passage through the superincumbent rocks. Repeated loud subterranean detonations are heard, resembling, so as frequently to be mistaken for, the firing of heavy artillery, or the rolling of musketry ; according to intensity. f The inhabitants of Mindanao, one of the Molucca islands, whenever their volcanos remain in a quiet state for an unusually long time, sacri- fice a slave to appease the wrath of the deity, which they suppose to inhabit them. Of Volcanos. 267 c These sounds are proved, by the immense distance to which they are propagated, and with a rapidity wholly out of proportion to their loudness near the spot from which they proceed, to be conveyed not by the air alone, but chiefly by the solid strata of the earth. ' Often, it is said, the state of the atmosphere assumes a peculiar character, offering an unusual closeness, stillness, and pressure. ' These threatening indications of an approaching crisis are prolonged for a greater or less time, and are accom- panied by the disappearance of springs, the drying up of wells, and such accidents as the cracking, splitting, and heaving of the substructure of the mountain, must naturally occasion. The eruption begins ; generally with one tre- mendous burst, which appears to shake the mountain from its foundations. Explosions of aeriform fluids, each pro- ducing a loud detonation, and gradually encreasing in vio- lence, succeed one another, with great rapidity, from the orifice of eruption, which is in almost every instance the central vent, or crater, of the mountain. This vent has usually been obstructed, during a long preceding period of repose, by the ruins of its sides, brought down by the wasting influence of the weather, and the shocks of earth- quakes, or by the ejections of previous minor eruptions. c The elastic fluids therefore, in their rapid escape, pror ject vertically upwards these loose accumulated matters, and the fragments of the more solid rocks, through which they have forced a passage. 6 The violence and rapid repetition of these projections, to which the same fragments are exposed upon falling again towards the orifice, reduce them to such tenuity that they are carried upwards by, and remain suspended for a time in, the heated clouds of aqueous vapour which are dis- charged, at the same time, in prodigious volumes, from the volcanic aperture. 6 The rise of these vapours, thus mingled with pulveru- Jent matter, produces the appearance of a high column of thick smoke, based on the edges of the cra^r, and appeur- 2 L 2 268 Of Vokanos. ing from a distance to consist of a mass of innumerable globular clouds, pressing on each other, and incessantly urged upwards by the continued explosions. At a certain height, determined of course by its relations of density with the atmosphere, this column dilates horizontally, and (unless driven in any particular direction by aerial cur- rents) spreads on all sides, into a dark and turbid circular cloud. In very favourable atmospheric circumstances, the cloud with the supporting column has the figure of an im- mense umbrella, or of the Italian pine, to which Pliny the younger compared that of the eruption of Vesuvius, in A. D. 79, and which was accurately reproduced in October, 1822. Forked and branching lightnings of great beauty are continually darted from different parts of the cloud, but principally its borders. Its continual encrease soon hides the light of day from the districts situated below it, and the gradual precipitation of the sand and ashes it con- tains, and which fall as the velocity of its progress is di- minished, contributes to envelope the atmosphere in gloom, and adds to the consternation of the inhabitants of the vicinity. ' Meantime the lava boils up the chimney of the volcano, The elastic fluids, by which it is traversed, rend and carry upward portions of its surface^ as they explode from it, and form a continual fiery fountain of still liquid and incandes- cent fragments, which from the velocity of their motion, present an appearance at a distance that has frequently been mistaken for flame. The internal column of lava con- tinuing to rise, it finds an issue, at length, either over the lowest lip of the crater, or from some crevice forced through the side, perhaps even at the foot of the mountain, from whence it flows in torrents. By night, the running lava appears at a white heat wherever the liquid interior of the current is visible ; but as upon contact with the air its sur- face is instantaneously congealed into a thick scoriform crust, the general tint of the outside is a glowing red, which gradually darkens as the solidified coating encreases in thickness. Of Volcanos. 269 * During day the lava is almost concealed from view by tlic torrents of aqueous vapour which rise from its whole surface in immense volumes, and unite themselves to the clouds of similar nature that hang over the mountain. 6 In some cases, no absolute escape of lava, in streams, takes place, scoriae alone being projected. ' In all cases where lava is emitted, its protrusion marks the crisis of the eruption ; which usually attains the maxi- mum of its violence a day or two after its commencement. The stopping of the lava in the same manner indicates the termination of the crisis, but, by no means, of the eruption itself. The gaseous explosions continue, with immense and scarcely diminished energy. 6 At length they cease to throw up liquid or red-hot scoria? ; the fragments projected are either blocks of older rocks, or consolidated scoriae. By degrees, these fragments, most of which fall back into the crater, become more and more comminuted by the immense trituration they sustain in the process of repeated projection and fall ; till at length clouds of sand alone and ashes, reduced in the end to an extraordinary degree of fineness, are carried upwards by the eructations of the aeriform fluids. 6 These explosions gradually decrease in violence, ap- pearing to be stifled by the accumulations of finely pul- verised fragments, which occupy the volcanic vent and impede their expansion. * The column of ashes projected becomes gradually shorter, until at length all struggle seems to cease : no further explosions are heard ; the eruption has terminated ; usually however not for many days, or even weeks, after attaining its maximum of violence. Soon the crumbling in of the crater's sides choaks up still further the volcanic orifice, and conceals it from view. An interval of quiet then commences, of a protracted duration, forming the other characteristic of the phase we are considering* ' These tremendous demonstrations of volcanic energy are always accompanied or followed by more or less violent meteoric phenomena; sometimes equally terrific and do 270 OfVokanos. structive \vith the former; the atmosphere appearing to share in the convulsion which agitates the earth. The summit of the volcanic mountain necessarily attracts and condenses the volumes of aqueous vapours which have risen from the volcanic orifice, and the lava emitted ; and hence a fail of rain takes place in prodigious quantity on its sides and base, producing torrents, which, carrying with them the ashes, sand, scoriae, and fragments, with which the slopes are strewed, rush, as deluges of liquid mud, towards the plains or vallies below, and cover them with vast de- posits of volcanic alluvium.* Perhaps the most fearful volcanic action upon record is that by which the mountain Jorullo suddenly arose in a most fertile tract of low country, on the west of the city of Mexico, in 1759. Sounds of the most alarming nature, accompanied by frequent earthquakes, continued from fifty to sixty days : about twenty-seven days of tranquillity suc- ceeded, when in the night of the 28th and 29th September the horrible subterraneous sounds recommenced. The in- habitants fled to the mountains, and a tract of ground^ from three to four square miles in extent, rose up in the shape of a bladder , and to the height of about 500 feet. The sur- face of the earth, softened by the action of the internal fire, was seen to heave like the sea in agitation ; flames arose, and fragments of burning rocks were ejected to a great height, through clouds of ashes, illumined by the fire. Two rivers fell into the burning opening and two rivers about a mile further west, now escape from under the vol- canic mass, as springs sufficiently warm to raise tjie ther- mometer to 126 of Fahrenheit. The volcanic tract around Jorullo is called by the natives Malpays, and it is covered by thousands of small cones termed hornitos (ovens) from six to ten feet in height, each being nfumarole, from which a thick vapour continues to ascend to the height of 22 to 32 feet. In the midst of these ovens six large masses arose to the height of 300 to 1600 feet above the plain, from a chasm, running N. N. E. and s. s. w. and the most elevated of them is the volcano of Jorullo, which is continually Of Volcanos. 271 burning. It has thrown up immense quantities of scorified and basaltic lavas containing fragments of primitive rocks. It is believed that the principal agents in volcanic phae- nomena are elastic fluids, which by their expansive force raise the surface of the earth, and the ashes, and even large masses of rock, ejecting them to a considerable distance. The observation of Mr. Scrope on Stromboli, which may be termed a volcano on a small scale, tends to prove the fact. ' The actual aperture of this volcano, at the bottom of its semicircular crater, is completely commanded by a neighbouring point of rock, of rather perilous access, from whence the surface of a body of melted lava, at a brilliant white heat, may be seen alternately rising and falling within the chasm which forms the vent of the volcano. At its maximum of elevation one or more immense bubbles seem to form on the surface of the lava, and rapidly swelling, explode with a loud detonation. This explosion drives upwards a shower of liquid lava, that, cooling rapidly in the air, falls in the form of scoriae. The surface of the lava is in turn depressed, and sinks about 20 feet, but is pro- pelled again upwards, in a few moments, by the rise of fresh bubbles, or volumes of elastic fluids, which escape in a similar manner ; and it is evidently this incessant evolu- tion of aeriform substances in vast quantities, which pre- serves the lava invariably at so great an elevation, withia the cone of Stromboli, and constitutes the permanent pha> nomena of its eruptions. 6 In this instance there evidently exists within and be- low the cone of Stromboli, a mass of lava, of unknown dimensions, permanently liquid, at an intense temperature, and continually traversed by successive volumes of aeriform fluids, which escape from its surface thus presenting ex- actly all the characters of a liquid in constant ebullition.' We are therefore to view the openings of volcanos as safety-valves; for if we could imagine the elastic fluids, which have performed such prodigies as have already been described, pent up and accumulating from causes which at 272 Of Volcanos. present are little understood, in a sphere opposing their liberation equally in every direction, we might proceed to imagine the destruction of the Earth itself from this very cause : happily however the force opposing their escape dif- fers greatly, and even the same volcano offers a resistance to their effects, which is altered by every eruption, and hence new vents open in some of them during each period of activity. It is said that all who have observed lava in the state in which it issues from a volcano attest, that the heat given out by it, produces little effect on a thermometer held at a few feet from it ; this is in part supposed to arise from the crust which immediately forms on the surface and which is a very imperfect conductor of heat. It is also said that at the moment of its emission, lava is not easily penetrable by a blunt rod, and hence it is argued that its liquidity is very imperfect ; hence also it has been sup- posed by Dolomieu and others, that lava, when at its greatest heat, is not in a state of perfect igneous fusion, but owes the mobility of its particles to some other cause. This notion has in the estimation of some observers re- ceived confirmation from the fact already noticed, that if a portion of lava of any quality be reduced to complete fusion , artificially, it hardens, by exposure into a glass, and not into a stony substance, as it commonly does immediately on ejection from a volcano. It is also said that if a portion of lava be taken from the margin of a current at a red heat, and which consolidates instantaneously before the eyes of the observer, it offers the same degree of stony, or crystalline texture, as lava which has cooled in the mass : hence it is argued that, as the instantaneous cooling of the portion could not allow time for the arrangement of the particles constituting it, into regular crystalline forms, these crystals must have existed in it at the time of its greatest heat, and if so, that the igneous fusion cannot have been complete. If then, we were to take it for granted that such is the nature of lava, we should next inquire by what means a Of Volcanos. 273 complete mobility of parts is maintained in lava in its ordinary state of a white heat, while still in ebullition in the volcano. It appears to be the opinion of Mr. Scrope that the crys- talline particles of which lava consists, are merely suspended while in a state of ebullition in the elastic fluid or fluids, which escape so abundantly at all times from a volcano, or frcm a comparatively recent current of lava, which conso- lidates at the moment of losing this fluid ; and he observes that the nature of this fluid has often been made the subject of direct experiment, and that it appears to be purely aque- ous vapour ; and he argues that the ebullition is produced by " the vaporization of minute quantities of water inter- posed between the laminae of the crystals" composing the lava. Thus he is of opinion that the crystalline particles of lava are allowed by the intervention of this disengaged fluid to slip or slide over each other, so that in the obsidian currents of Lipari, Volcano, Iceland, Teneriffe, Bourbon, &c. the longest axis of the crystals they include are parallel to the direction of the movement. He further observes that " the existence of water in lava may seem, at first, a strange and almost incredible notion," and then proceeds to shew that the experiments of Knox and Spallanzani detected water in mechanical mixture. The doctrine is startling, and may require long observation to confirm it. Many theories have .been proposed to account for the cause or origin of volcanos. It amounts almost to certainty that they are deeply seated in the Earth, as many of the phenomena tend to evince ; but whether we are to regard each volcano or vol- canic range to have a separate origin, or whether we arc to consider volcanic openings in the aggregate only as safety-valves or chimnies to one vast collection of volcanic matter perhaps always in some degree of ebullition in the interior of the earth, we have no means of ascertaining. Their effects, whether taken generally or particularly, are 274 Of Volcanos. however such as would lead us to inquire after some great and efficient cause. Some of the earlier observers, among whom was Werner, inclined to attribute them to the spontaneous combustion of beds of coal ; others have sought their origin among other inflammables, as beds of sulphur, or vast quantities of petro- leum collected in the caverns of the Earth, ignited by some spontaneously combustible substance ; and Lemery made an experiment tending to shew that a mixture of iron-filings and sulphur kneaded with water into a thick paste, first wrapped in a cloth and then buried under ground, would in a few hours become warm, swell, raise the earth above it, give out sulphureous vapours, sometimes with flame, more rarely with explosion. These notions however, appear to have given way to cer- tain of the modern discoveries in chemistry. Sir H. Davy has proved that the bases of several of the earths and alkalies are of a combustible nature under certain circumstances. Hence as the bases of the constituents of rocks have been proved to be inflammable principles^ and have become what we see them to be, merely by their union with oxygen^ it has been argued as a probable circumstance, that these bases may still exist in the interior of the Earth, in the pure or unoxidized state. It has also been argued that if water were to be admitted to them in that state, the effects that would immediately be produced, would be equal to the production of all the phenomena attendant on volcanos. The water would immediately be decomposed ; heat would be given out by the combination of these bases with oxygen, and hence an immediate igneous action upon all the substances which heretofore protected these bases from the intrusion of the water. The detail of circumstances which would follow being purely chemical, are not adapted for discussion here : but I would refer the inquiring reader to page 389 of Dr. Daubeny's c Description of active and extinct Volcanos,' in which these effects are detailed at large. Concluding observation*. 275 We have now completed the object we had io view, in dedicating seven evenings to the investigation of simple and compound mineral bodies j namely, an outline of the great masses composing the crust of the globe; of their ar- rangement; and of their component substances. In this view I have as much as possible studied brevity. It may be well imagined that there are many facts, con- siderations, and enquiries, of which nothing has been said ; facts in regard to the relative nature and positions of com- pound mineral bodies and masses ; considerations and en- quiries into which those facts would necessarily lead. Enough, however, I trust, has been said to show that geologists have truth for their object. That faculty of ge- nius which consists in invention no longer presides ; the theories which attributed the origin of the globe to a por- tion of the sun struck off by a comet, and fifty others equally absurd, are gone by and neglected. Patient and profound investigation has taken their place ; producing research nearly to the summits of our most elevated moun- tains, and to the greatest depths to which the miner can descend. But since it is computed that all our researches do not extend further into the Earth, than, by comparison, the thickness of the paper which covers a globe of three feet in diameter, is to that globe ; it will follow that we do not possess any knowledge of what the central parts of the Earth are actually constituted. We have however the most indubitable evidence that the crust of the globe has been subjected to revolutions, both partial and general. We are assured by the numerous facts that have been quoted, and by far the more numerous which yet remain, that the sea must have changed both its place and its height. Proofs have been adduced that animal life has repeatedly and largely fallen the victim to these terrible events. There seems reason to conclude that some animals have been destroyed by sudden inundations ; that others have been laid dry in consequence of the bottom of the sea 2 M 2 276 Concluding observations. being suddenly elevated; and that these calamities have caused great changes in the outer crust of the globe. It seems also clear, that since thes,e first and greater commo- tions, those which followed, uniformly acted at a less depth and less generally. We have seen that the researches of geologists have ascertained that of those animated beings of which the remains are enclosed in those rocks which imme- diately rest upon primitive rocks, the races have become ex- tinct; that the newer rocks contain the remains of animals more nearly approaching to, but not absolutely of the same species as, those inhabiting our present seas; but that the newest contain only the remains of such animals as now exist in the seas, together with the bones of large land and amphibious animals. Every part of the globe distinctly bears the impress of these great and terrible events. The appearances of change and ruin are stamped on every feature. Change and ruin by which not a particle of the creation has been lost, but which have been repeated and are distinctly marked by the genera and species of the organic remains they enclose. Thus, those fossils and petrifactions which heretofore were carefully collected as curiosities, now possess a value greater than as mere curiosities. They are to the globe what coins are to the history of its inhabitants; they denote the period of revolution ; they ascertain at least compara- tive dates. If the inquiry should arise, What benefit has resulted from ruin so extensive and so general? the- answer is ob- vious; soil and fertility. If for a moment we imagine a world composed only of those rocks which we call primi- tive, which bear no marks of ruin, enclose no organic re- mains ; we know from the nature of their component sub- stances, that their exposure to the action of the elements during very many ages, would scarcely so separate and disintegrate them, as to produce a soil capable of any con- siderable vegetation ; in other words, would fit the Earth to receive and to maintain an extensive and almost univer- sal population. A large and fertile part of England, is Concluding observations. 277 composed of the ruin of rocks to a considerable depth ; and this greatly obtains in all the most level and most fertile countries. Are we not then in degree justified in assuming that this great ruin was designed to fit and pre- pare the Earth for the support of the numerous animal tribes that inhabit it; most especially for MAN; who, doubtless from his superior intellectual endowments, has emphatically been termed 6 the Lord of the Creation.' But our inquiries into utility need not stop here. All our researches have evinced such unquestionable proofs of design and contrivance, that it is impossible not to see them y and if we see them, it is or ought to be equally im- possible not to ascribe them to the Great Artificer of the universe. This indeed is the reasonable end and aim of all our inquiries, and of all our philosophizing. Without mountains, what in all probability would be the Earth ? A swamp or a sandy desert ; and the atmosphere a receptacle of noisome and pestilential exhalation. As conductors of the electric fluid, mountains contribute to the production of rain, which fertilizes the Earth and pu- rifies the atmosphere. They are the principal repositories of metallic ores. Their benefits, therefore, are great and extensive. Metallic ores and mineral substances, it may be remarked, either in the simple or compound state, are found in quan- tity admirably apportioned to their utility ; and, in the same proportion, with whatsoever they may be combined, they are generally most readily and easily freed from those sub- stances with which they are compounded. Is it possible for one moment to doubt whether all this exhibits design and contrivance for the benefit of Man? But further ; is not design manifest in regard to the de- positions of salt, of coal, and of iron, so essential to man ? Suppose these to have taken place between the earlier rocks, or in the masses of primitive mountains, or any where except where we find them ; that is, just beneath the surface ; they would in that case have been nearly lost to man. Can we appreciate their present benefits ? Can 278 Concluding observations, we doubt that there was design in placing them where we iind them ? Some circumstances regarding the position of the coal and iron in Shropshire, merit our particular notice. The iron-stone lies imbedded in a kind of clay, in which appear the first beds of coal, so essential to the process of smelting the iron. Larger beds of coal are found beneath ; the most important of which lies on a sand or sandstone. When in the form of sand, it is of great use in making tlie moulds which receive the melted iron ; when in that of sandstone it is employed to line the iron furnaces, on ac- count of its enduring heat for a great length of time with- out injury. But this is not all ; the sand or sandstone re- poses on limestone, which is essential as a flux in the smelt- ing of the iron ore. Is not design for the benefit of man apparent in this arrangement ? But in speaking of soil and fertility as the consequence of the decay and ruin every where to be observed, I omitted one important consideration ; namely, the decay of vege- tables, which so essentially contributes to fertility, as prin- cipally composing what we call mould. But there is one exception to the general rule in regard to the decay of vegetable matter, not sufficiently noticed, as being an ex- ception in the favour of Man ; but which demands a thought. The leaf, after it has fallen, enriches our soil , the gardener esteems it an excellent manure ; but the tree that bore the leaf, when deprived of life, decays not until after a long period of time ; not until it has long been in the service of Man. Without wood, Jiow should be able to accomplish the many purposes to which it is applied ? Where could we find a substitute ? This, I grant, is a digression ; but it is almost the only one I have allowed myself. I shall perhaps be excused, when it is considered, that it is adding another proof, in itself rather too obvious to attract much notice, to the many already adduced, that design and contrivance are every where manifest, and in every thing intended for the advantage of Man* APPENDIX. HEIGHTS OF MOUNTAINS. THIS subject may seem rather to belong to Physical Geography than to Geology ; and though some have affected to view it as altogether one of idle curiosity, it may surely be affirmed that the idle alone could have framed the thought. Independently of their forming the majestic and sublime features of Nature, mountains have positive charms for man, inasmuch as they constitute the principal depo- sitaries of the mineral treasures in search of which he is so ceaselessly active. In a geological point of view they are highly important as exhibiting in their ravines and pre- cipices, the rocks of which the crust of the globe is con- stituted, in a manner far more satisfactory than they could be observed by any other means. In the plate opposite to the title page are shewn the comparative heights of various hills and mountains in dif- ferent quarters of the globe : but in this feeble attempt at exhibiting their relative heights, their absolute form has been but little attended to, as will be sufficiently obvious when it is recollected that in general a mountain is not an insulated mass as there represented, but commonly forms a part of a chain, often of great extent : it has however been remarked by travellers that Gader Idris in North Wales, is, considering its want of great elevation, a remarably fine instance of an insulated mountain.. To those however, who like us, inhabit a low and almost level country, Cader Idris and Snowden are objects of wonder and admiration : but when these, or Ben Nevis, which attains the height of 4365 feet above the level of the sea, and is the highest mountain in Britain, are compared with the majestic elevations of the European or American continents, or with the still more stupendous mountains of Asia, they sink in our estimation into mere hillocks ; and the great Pyramid of Egypt, that wonder of ages, which is 475 feet in height, seems as nothing in comparative bulk. 280 Appendix Heights of Mountains. The highest mountain in Europe is Mont Blanc in Swit- zerland, which attains the height of 15,630 feet above the sea ; but there are several others nearly as lofty. One of the highest mountains in Asia is Petcha, or Hamar in Chinese Tartary, which is estimated to rise 15,000 feet above the plains of China; but the Himalay range in Thibet is still higher. The loftiest summit of this range, and as it is believed, in the world, is Dhwalagiri on the White Mountain, which in a memoir in the 12th volume of the Asiatic Researches is stated to attain the height of 26,462 feet above the sea : twenty-seven peaks in this range are covered by perpetual snow ; twenty of them exceed 20,000 feet in height, the lowest being 15,733 feet high. In Africa, the loftiest mountains are believed to be those of Geesh, estimated at 15,000 feet above the level of the sea. Of the American continent, Chimborazo, the highest summit of the Andes, is 21,451 feet above the sea level, and is the highest point of the whole, but there are fourteen other mountains in that range, whose summits rise between 10 and 20,000 feet above the sea, several of which are volcanos. In Britain, secondary rocks attain an elevation of about 3,500 feet, in the Alps of 7,000 feet, in the Andes about 14,000 feet. The sides of the more lofty mountains of Asia are covered by secondary deposits, of which, however, the height has not been ascertained. The greatest height to which travellers have ascended, was attained by Humboldt, Bonpland, and Montufar, who, on June 23d, 1802, were on the Andes at the height of 19,374 feet above the sea. Aerostatic travellers only have exceeded this. On September 16th, 1814, Gay Lussac, an eminent French chemist, ascended in a balloon about 3,500 feet higher. The lowest limit of perpetual snow on the mountains of America is about 15,000 feet above the sea; on the Alps about 8,400 feet, but in Norway in latitude 71 it is only about 2,200, feet above the sea. On the Andes, lichen is found about 18,000 feet high; the condor eagle is known to soar about 2,000 feet higher. England and Wales. 281 ALTITUDES of the STATIONS^ and of several other REMARKABLE HILLS in England and Wales^ in English feet above the level of the sea, with occa- sional notices of their constituent rocks. Computed from the observations made in the course of the Trigonometrical Survey. Feet * Agnes Beacon (St.) Cornwall Clay-slate 621 Allington Knoll, Kent Weald clay ..... 329 Allport Heights, Derbyshire Millstone grit . . . 980 Alnwick Moor, Northumberland. 808 Ann's Hill (St.) Surrey Upper Marine . . 240 Arbury Hill, Northamptonshire . . . Oolite 804 Arran Fowddy, Merionethshire. . .Greywacke slate. 2955 Arrenig, Merionethshire Greywacke slate . 2809 Ash Beacon, Somerset 655 Ashley Heath, Staffordshire 801 Axedge, Derbyshire . 1753 Bagborough, Somerset .: Greywacke slate. 1270 Bagshot Heath, Surrey Upper Marine. . . 463 Banstead, Surrey Plastic clay 576 Bar Beacon, Staffordshire New red sandstone 653 Bardon Hill, Leicestershire Greywacke 853 Barnaby Moor, Yorkshire 784 Beacon Hill, Wiltshire 690 Beacons of Brecknock, Brecknock Old red sandstone 2862 Beachy Head, Sussex Chalk 564 Beeston Castle (Top of) Cheshire 556 Belle-field Hill, Cheshire 401 Beryl Hill, Lancashire 128 Billing Beacon, Lancashire 633 Bindown, Cornwall 658 Black Comb, Cumberland Clay-slate 1919 Black Down, Dorsetshire . Chalk * 817 Black Hambleton Down, Yorkshire Oolite 1246 Blackheddon, Northumberland 646 Bleasdale Forest, Lancashire. .... Millstone grit . . . 1709 Bodmin Down, Cornwall 645 Bolt Head, Devonshire 630 Boulsworth Hill, Lancashire Millstone grit . . . 1689 Botley Hill, Surrey Chalk 880 2N 282 Appendix Heights of Mountains. Feet Botton Head, Yorkshire Oolite 1485 Bow Brickill, Bucks Iron sand 683 Bow Fell, Cumberland Clay-slate 291 1 Bow Hill, Sussex Chalk 702 Bradfield Point, Yorkshire 1246 Bradley Knoll, Somersetshire 973 Brandon Mount, Durham 875 Brenin Fawr, Pembrokeshire 1285 Brightling Down, Sussex 6 J6 Broadway Beacon, Gloucestershire Oolite 1086 Brown Clee Hill, Shropshire Trap 1805 Brown Willy, Cornwall Granite 1368 Bull Barrow, Dorsetshire . . . . a 927 Burian (St.), Cornwall 415 Burleigh Moor, Yorkshire 553 Butser, Hill, Hampshire Chalk 917 Butterton Hill, Devonshire Granite 1203 Bwlch Mawr, Caernarvonshire . . . Greywacke slate . 1 673 Cader Ferwyn, Merionethshire. . . . Greywacke slate. 2563 Cader Idris, Merionethshire Green st. & slates 2914 Cadon, Barrow, Cornwall Clay slate 1011 Caermarthen Vau, Caermarthensh 2596 Calf Hill, Westmoreland 2188 Capellante, Brecknockshire Old red sandstone 2394 Capel Kynon, Caernarvonshire 1046 Cam Bonellis, Cornwall Granite , . 822 Cam Minnis, Cornwall - 805 Carnedd David, Caernarvonshire. . Greywacke 3427 Carnedd Llewellyn, Caernarvonsh. Greywacke 3469 Carraton Hill, Cornwall 1208 Castle Ring, Staffordshire New red sandstone 715 Cawsand Beacon, Devonshire .... Granite 1792 Cefn Bryn, Glamorganshire Old red sandstone 583 Chanctonbury Hill, Sussex Chalk 814 Charton Common, Dorset 582 Cheviot, Northumberland Greenstone ? .... 2658 Clifton Beacon, Yorkshire 417 Cleave Down, Gloucestershire .... Oolite 1 134 Collier Law, Durham Millstone grit . . . 1678 Coniston Fell, Lancashire Greywacke 2577 Cradle Mountain, Brecknockshire . Old red sandstone 2545 Cross Fell, Cumberland Coal measures. . . 2901 Crowborough Beacon, Sussex . . . .Iron sand 804 Cern y Brain Mountain, Detibighsh. Mountain limest. ? 1 857 England and Wales. 2$3 Feet Danby Beacon, Yorkshire Oolite 966 Deadman, Cornwall 379 Dean Hill, Hampshire Plastic clay 539 Delamere Forest, Cheshire New red sandstone 596 Dent Hill, Cumberland Greywacke 1115 Ditchling Beacon, Sussex Chalk 858 Dover Castle, Kent Chalk 469 Dumpdon Hill, Dorset 879 Dundon Beacon, Somerset 360 Dunkery Beacon, Somerset ..... Greywacke ..... 1668 Dundry Beacon, Somerset Oolite 790 Dunnose, Isle of Wight Iron sand 792 Dwggan near Builth, Brecknocksh. Old red sandstone 2071 Easington Heights, Yorkshire .... Lias 681 Epwell Hill, Oxford Oolite f ... 836 Fairlight Down, Sussex Chalk 599 FarleyDown (nearBath)6?/o'ster*A. Oolite 700 Firle Beacon, Sussex Chalk 820 Folkstone Turnpike, Kent Chalk 575 Frant Steeple (Top) Sussex Iron sand 659 Furland (near Dartmouth) Devon . Greywacke 589 Garreg Mountain, Flintshire , 835 Garth (The) Glamorganshire 981 Gerwyn Goch, Caernarvonshire . .Greywacke 1723 Go Hill, Lancashire , 304 Goudhurst, Kent 497 Grasmere Fell, Cumberland 2756 Greenwich Observatory, Kent Plastic clay 214 Gringley on the Hill, Yorkshire 235 Gwaunysgaer Down, Flintshire. . .M. limestone ?. . . 732 Haldon (Little), Devonshire Greensand. ... . 818 Hanger Hill (Tower), Middlesex 251 Hathersedge, Derbyshire Millstone grit ... ] 377 Haw keston Obelisk (Top) Shropsh 812 Hedgehope, Northumberland Greenstone ? . . . . 2347 Helvellin, Cumberland Clay slate 3055 Hensbarrow Beacon, Cornwall. . . . Granite ........ 1034 Heswell Hill, Cheshire New red sandstone 475 Highbeech, Essex London clay .... 750 Highclere Beacon, Hampshire .... Chalk 900 I fiqhgate Down, Pembrokeshire . . Old red sandstone 294 284 Appendix Heights of Mountains . Feet High Nook, near Dimchurch, Kent . . , < 28 High Pike, Cumberland Clay slate 2101 Hind Head, Surrey Green sand 923 Holland Hill, Nottinghamshire .... New red sandstone 487 Holme Moss, Derbyshire Coal measures . . . 1859 Hollingborn Hill, Kent ..Chalk 616 Holy-Head Mountain, Anglesea . . Clay slate ? 709 Hundred Acres, Surrey Plastic clay 443 Hunsley Beacon, Yorskshire Chalk 531 Ingleborough Hill, Yorkshire Mountain limest. 2361 Inkpin Beacon, Hampshire Chalk 1011 Kensworth, Hertfordshire Chalk 904 Kilhope Law, Durham Mountain limest. 2196 King's Arbour, Middlesex London clay .... 132 Kit Hill, Cornwall Granite. 1067 Lansdown, Someretshire Oolite 813 Ledstone Beacon, Yorkshire 278 Leith Hill, Surrey Greensand 993 Lillyhoe, Hertfordshire Chalk 664 LlandinamMountainjMow/g-owerz/s. Greywacke ..... 1898 Llanelian Mountain, Denbighshire Transition limest. 1110 Llangeinor Mountain, Glamorgans. Coal measures... 1859 Llannon, Caermarthenshire Greywacke slate. 912 Llwydiart Mountain, Anglesea . . . Clay slate ? 523 Long Mount Forest, Shropshire . . Greywacke 1674 Long Mountain, Montgomeryshire Greywacke 1330 Loosehoe, Yorkshire Oolite 1404 Lord's Seat, Yorkshire Millstone grit ... 1715 Maker Heights, Cornwall ... Greywacke ? . . . . 402 Malvern Hills, Worcestershire . .. Hornblende rock 1444 Marros Beacon, Caermarthenshire 514 Margam Down, Glamorganshire . . Coal measures . . . 1099 May Hill, Gloucestershire Transition limest. 965 Moel Fammau, Denbighshire Greywacke 1845 Moel Morwith, Denbighshire Greywacke 1767 Moel Issa, Denbighshire Mountain limest. 1037 Moel Rhyddlad, Anglesea Clay slate ? 465 Moor Lynch (Windmill) Somerset Lias 330 Motteston Down, Isle of Wight . . . Chalk 698 Mow Copt, Cheshire Coal measures ... 1091 Muzzle Hill, Bucks 744 England and Wales. 285 Feet ?ettlebed (Windmill) Oxfordshire 820 New Inn Hill, Caer mart hens hire * 1163 Newton Down, Pembrokeshire . . . Old red sandstone 322 Nine Barrow Down, Dorsetshire. . Chalk 642 Nine Standards, Westmoreland. . .Millstone grit ... 2136 North Berule, Isle of Man Greywacke 1804 Norwood, Surrey London clay .... 389 Nuffield Common, Oxfordshire . . . Chalk 757 Ogmoor Down, Glamorganshire 292 Paddlesworth, Kent Chalk 642 Pen Hill, Yorkshire 2245 Pendle Hill, Lancashire , Millstone grit . . . 1803 Pengarn, Merionethshire Greywacke ? . , . . 1510 Penmaen Maur, Caernarvonshire 1540 Pennigant Hill, Yorkshire Mountain limest. 2270 Pertinney, Cornwall 689 Pillar, Cumberland 2893 Pilsdon Hill, Dorsetshire Green sand ? . . . . 934 Plumstone Down, Pembrokeshire . Greenstone 573 Plynlimmon, Cardiganshire Greywacke 2463 Pontop Pike, Durham , . .Coal measures. . . 1018 Portsdown Hill, Hampshire Chalk 447 Precellx Top, Pembrokeshire 1754 Radnor Forest, Radnorshire Greywacke 2163 Rhiw Mountain, Caernarvonshire . Greywacke ? . . . . 1013 Rippin Tor, Devon Granite 1549 Rivel Mountain, Caernarvonshire . Greywacke ? . . . . 1866 Rivington Hill, Lancashire Millstone grit . . . 1545 Rodney's Pillar (Base of) Montgom.Trap 1 1 99 Rook's Hill, Sussex Chalk 702 Roseberry Topping, Yorkshire . . . Oolite . . . , 1022 Rufflaw, Northumberland 595 Rumbles Moor, Yorkshire Millstone grit . . . 1308 Saddleback, Cumberland .Greywacke ? 2787 Sarum (Old), Wilts Chalk 339 Sea Fell (Low Point), Cumberland Clay slate 3092 Sea Fell (High Point), Cumberland Clay slate 3166 Scilly Bank, Cumberland .....* 500 Scutchamfly Beacon, Berks 853 Sennen, Cornwall Granite 387 Sherwood Forest, Nottinghamshire New red sandstone 600 286 Appendix Heights of Mountains. Feet Shooters Hill, Kent Plastic clay 446 Shunnor Fell, Yorkshire Millstone grit . . . 2329 Simonside Hill, Northumberland. . Coal measures . . . 1407 Skiddaw, Cumberland Greywacke ? . . . . 3022 Snea Fell 2004 Snow don, Caernarvonshire Grey wacke 3571 Staincross Heights, Yorkshire 514 Stathern Point, Leicestershire .... Oolite 490 Stockbridge Hill, Hants 620 St. Stephen's Down, Cornwall .... Granite 605 Stow Hill, Herefordshire 1417 Stow on the Wold, Gloucestershire 883 Swingfield Steeple (Top), Kent 530 Symond's Hill, Gloucestershire 795 Talsarn, Cardiganshire Greywacke 1 143 Tenterden Steeple, Kent 322 Thorney Down, Somerset Mountain limest. 6 JO Tregarrori Down, Cardiganshire . . Greywacke 1747 Trelleg Beacon, Monmouthshire 101 1 Trevose Head, Cornwall 274 Water Cragg, Yorkshire 2186 AVeaver Hill, Staffordshire Millstone grit ... 1154 Wendover Down, Buckinghamshire 905 Westhury Down, Wilts 775 Whernside(inIngletonFells)For&s.Mountain limest. 2384 Whernside(in KettlewellDale)<#fto Millstone grit . . . 2263 White Horse Hill, Berkshire Chalk .. 893 Whiteham Hill, Berkshire 576 Wilton Beacon, Yorkshire 809 Wingreen Hill, Dorsetshire 941 Wittle Hill, Lancashire 1614 Wordeslow Hill, Durham 632 Wrekin, Shropshire 1 320 Ynaliog Mountain, Caernarvonshire .... , . . . . v 584 Scotland 287 Mountains of Scotland. The heights are chiefly extracted from Wilson's history of Mountains. Such as have the mark * prefixed are from the Trigonometrical Survey. Those having the mark t are from Forsyth's Beauties of Scotland. Feet Annan Hill, Dumfriesshire ..... Coal measures . . . 256 Arthur's Seat, near Edinburg . . . Trap .......... 810 Barry Hill, PertJishire ........................ 688 Bedinam braw in Glencoe, Ar- ) 3150 gyleshire ................ $ Beinbhanfion, Isle of Arran .................... 2950 Beinmore, Assynt, Sutherlandshire .............. 3903 Beinn-a-Chalois, Pap of Jura .................. 2359 rBeinn-an-oir, highest Pap of > 2490 Jura, Argyllshire ......... ) f Beinn Sheunta, Pap of Jura ................... 3359 Sienite ......... 3550 Beinn Gloe, Perthshire ........ Mica-slate ...... 3724 Belmont Hill, Perthshire ....... New red sandstone 759 Benachie, Aberdeenshire ....................... 100O Benachally, Perthshire ........................ 1800 Bencairn, Kircudbright ........................ 1200 Benchochan, Perthshire ........ Mica-slate ...... ? 3000 Ben Chonzie, Perthshire ... k ... Mica-slate ...... 2922 tBen Clack, Perthshire .................... ----- 2420 Ben Cleugh (highest summit of ) 94^0 the Ochils) Clackmananshire) iBen Doig ................................... 355O tBen Gload .................................. 3724 Ben Ivenou, Perthshire ....................... ? 3000 tBen Lawers, Perthshire ~ ....... Mica-slate ...... 4015 Ben Ledi, Perthshire ......................... 3009 Ben Lomond, Stirlingshire ...... Mica-slate ...... 3262 t Ben More, Perthshire ......... Mica-slate ...... 3907 Ben Nevis, Internes shire, > .......... about 43g5 highest mountain in Britain.) Ben Voirlick, Perthshire ....... Mica-slate ...... 3300 Ben Wevis, Ross-shire ......... Mica-slate . , ____ 3720 Birnham Hill, Perthshire ...................... 1580 Blackhouse Heights, Selkirkshire Greywacke ..... 2370 iBlacksall End, Ayrshire ........ New red sandst. . 1540 288 Appendix Heights of Mountains. Feet Black Larg, Dumfriesshire Greywacke 2890 Braid Hills, Mid Lothian Trap. 690 Broad Law, Peeblcshire Greywacke 2800 Buck Hill, Aberdeenshire 2377 Burnswark Hill, Dumfriesshire. . Coal measures . . . 740 Caernethan, Mid Lothian Trap 1700 Cairn Ferg, Aberdeenshire . . 2100 Cairn Kinnon, Dumfriesshire. . . . Greywacke 2080 Cairn Naple, West Lothian 980 Cairn Monearn, Inverness-shire. .Mica-slate 1020 Cairngorum, Inverness -shire Granite 4050 tCairnhaerow, Kirkcudbright 1100 Cairnsmuir, IVigton and Kirk- ) !- cudbright $ > l737 Cairn-harrah, .... ditto 1110 Cairn-pat, ditto 800 Calton Hill, near Edinburgh .... Trap 350 Campsie Hills, Stirlingshire Trap 1500 Garden Hill, Peeblesshire 1400 Carleton Hill, Ayrshire Greywacke 1554 tCarter Fell, Roxburghshire Greywacke 1502 Castle Law, Mid Lothian Trap 1390 Cat Law, Angus or Forfar Mica-slate 2264 Cheviot Hills, Roxburghshire. . . . Sienite 2680 Cobler, Argyleshire Mica-slate 2389 Cocklereu, West Lothian 980 Constitution Hill, Dumfriesshire.. Greywacke 1004 Corstorphine Hill, Mid Lothian . . Trap 470 Craig of Ailsa, Ayrshire Sienite ? 940 tCraig Owl, Forfarshire 1700 Craig Phatrick, Inverness-shire. . New red sandst. . 1150 Craiglockart Hill, Mid Lothian . . Trap 540 Craigmillar, Mid Lothian Coal-measures . . . 360 Criffle, Kirkcudbright Sienite 1895 fCruachan Brinn, Argyleshire. 3390 Dalmahoy Hill, Mid Lotluan Trap 680 Dollaburn, Peeblesshire Greywacke ? 2840 Dunse Law, Berwickshire Greywacke 630 Dunian's Hill, Roxburghshire . . . New red sandst. . 1024 Dundroiffh, or Druids Hill, PeeblLhire Dunsinnan Hill, Perthshire Trap 1024 'Dunnichen Hill, Forfar New red sandstone 720 *Dunrigs, Roxburghshire Greywacke 2408 Scotland. 289 Feet *Elden Hills, near Melrose Trap 1364 Erikstaenebraehead,/)7w/ne.s.v/MreGreywacke 1118 Ettrick Pen, Dumfriesshire Greywacke 2220 Fare Hill, Aberdeenshire 1793 Garrach, Aberdeenshire % 3000 Glumseugh, Peeblesshire Greywacke 2200 Goatfield, Isle of Arran Granite 2945 Hanginshaw, Selkirkshire 1980 f Hartfell, Dumfriesshire Greywacke 3300 Hill-house Hill, IVest Lothian 698 Hillscleugh, Peeblesshire Greywacke 2100 Kerlavich, Kincardmeshire 1890 King's Seat, Perthshire Mica-slate 1238 Kinpurnie, Perthshire New red sandst. . 1151 Kirk Yetton, Mid Lothian Trap 1 544 Kloachnabane, Kincardmeshire . .Mica-slate 2370 Knock Hill, Eanffsldre Mica-slate 2500 tKnocknorman, Ayrshire Greywacke 1 554 f Knockdoban, Ayrshire Greywacke 1950 tKnockendoch, Kirkcudbright 1500 Langholm Hill, Dumfriesshire . . . Greywacke 1204 *Largo Law, Fifeshire Coal-measures . . . 952 Lochavon Hill, Banffshire 1750 Logan-house Hill, Mid Lothian . . Trap 1700 *Lomond Hills (East) Coal-measures . . . 1466 * Lomond Hills (West) Coal-measures ... 1712 Lowther Hill, Dumfriesshire .... Greywacke 2522 *Lumsdane Hill 725 tMarto, Roxburghshire 858 Meagle, Selkirkshire Greywacke 1480 Meal Fourvounny Mica-slate 3070 Millenwood Fell, Roxburgshire . . Greywacke 2000 Minchmoor Hill, Peeblesshire . . . Greywacke 2000 Minto Hill, Roxburgshire New red sandstone 858 Misty Law, Renfrewshire Trap 1240 Moffatt, Dumfriesshire 582 *Mordington Hill C41 Mormond Hill, Aberdeenshire . . .Mica-slate 810 Mount Battock, Kincardmeshire .Mica-slate 3450 Mulbrax Hill, Aberdeenshire^ 2700 2 o 290 Appendix Heights of Mountains. Feet Neil Craig, Renfrewshire 820 Ord of Caithness G ranite 1250 Paps of Caithness .- 1929 Peat Law, Selkirkshire 1694 Peter Hill, Aberdeenshire 2700 *Queensberry Hill, Dumfriesshire. Greywacke 2259 Ruber's Law, Roxburghshire. . . . Greywacke . . . . , 1419 Salisbury Craigs, Mid Lothian . . . Trap 550 t Sayrs Law 1739 Scairsoch, AberdeemMre Mica-slate 3400 +Schihallien, Perthshire . 3564 *Soutra Hill 1716 Spittal Law, Mid Lothian New red sandst. . 1360 Tarprain Law, East Lothian .... Trap 700 Tennis Hill, Dumfriesshire Greywacke 1346 Tudhope, Roxburghshire Greywacke 1830 Wardlaw, Selkirkshire Greywacke 1 900 *Whin Fell 2241 * Wisphill, Roxburghshire Greywacke 1 940 Mountains in Ireland. Chiefly extracted from Dr. Berger'-s and Mr. Weaver's papers, in the Transactions of the Geological Society of London. Such as have an asterisk prefixed are From Wilson's List of Mountains. Feet Agnew's Hill 1450 *Alt-English-IIill, Londonderry 1300 Ballinglass Hill, WiMow Mica slate 1271 Ballinvallow Hills, Wicklow Clay slate 1000 Ballypatrick, Antrim Trap on Chalk . . 965 Barensdale Mountains, Louth 1644 Beagh Mor, Antrim 974 en Bhoy, Londonderry 1220 Benbradach, Londonderry Trap on Chalk . . 1569 Bengore 328 Benyevenach, Londonderry Trap on Chalk . . 1145 Ireland. 291 Feet Mountain, Downshirc . . .Granite 2396 Black Mountains, Antrim 1040 J)iisselstown Hill 1330 Bray Head, Wicklow Quartz rock 807 Cadeen, Wicklow Mica si. on Granite 21 58 Cairn Togher, Londonderry Trap 1600 Cadyhill, Londonderry 1030 Cavehill Top, Antrim Basalt 1064 Comaderry, Wicklow Granite 2263 *Commeragh Ridge, Waterford 2160 Coolcoscrehan, Londonderry . . . .Mica slate 1292 Coolnagopag, Antrim Trap on Chalk . . 1130 Conlig-liill Bangor, Downshire 473 Cragnashoach, Londonderry ... .Trap on Red sand 864 Craig Rammer, Antrim 559 *Croagh-Patrick, Mayo 2640 *Croaghan-Kinshelly, Arklow ....... 1850 Croaghmore, Antrim 471 Crogan Kinshela, Wicklow Clay slate 2064 *Cf onebane, Wicklow 1000 Crossbill Top, Antrim Trap 508 Djouce Mountain, Wicklow Granite 2392 Divis Mountain, Antrim Basalt . '. 1475 Donald's Hill, Londonderry Trap on Chalk . . 1399 Down Hill, Londonderry 255 Duncanstown Hills about 1000 Dunlogan Hill, Londonderry . . . .Mica slate 1467 Eade's-town Hill 1339 Fairhead, Antrim 535 Fathom Mountains, Armagh .... Granite 820 Faughell or Foughall Ms. Armagh . . 822 Fin Glen, Londonderry Mica slate ? 2097 Foy Mountain, Louth 1850 Golding Mountain, Louth 1055 Great Sugar Loaf, Wicklow Quartz rock 2004 Kedy Hill, Londonderry Trap on Chalk . . 103Q Kippure, Wicklow Granite 2527 Kilcashel Hills about 1000 Kilranda Hill 1295 *Knock-mele-down, Waterford 2790 Knocklead, Antrim Basalt on Chalk . 1820 292 Appendix Heights of Mountains. Ireland. Feet Little Sugar Loaf 1 183 Lower* Lough Bray . . 1492 Lugnaquilla, IVicklow Mica si. on Granite 3070 *Macgillicuddy's Reeks, Kerry } the highest mountains in > 3405 Ireland J Malabwea Hill, Londonderry 850 *Mangerton, Kerry , above Lake ) of Killarney f ' Moneynieny, Londonderry Mica slate ? 1477 Mullaghash, Londonderry Mica slate ? 1677 *Nephin Mountain, Mayo 2640 Pleskin, Antrim 354 Sawell, Londonderry Mica slate 2257 Sandy Brae Hill, Antrim Porphyry 537 Scrabo Hill, Downs/lire Old Red sandstone 483 Seechon, IVicklow Mica slate 2150 Shy nan's Hill, Wicklow Clay slate 1351 Slemish Mountain, Antrim 1 13O Slieve Gullen, Armagh Granite 1900 Slieve Girkin, or Newry Moun-) ^ ta,n s , Armagh \ Gramte 134 Slieve Muck, Downshire Granite 2290 Slieve Snaven (Slieve Birna ?) dittoGranite 2370 Slieve Donard, Dozvnshire Granite 2654 Slieve Croob, Downshire 1204 Slieve Nory, Antrim Basalt on Chalk . 1530 Slieve Cross, Antrim 742 Slieve Anisky, Downshire 170 Slieve-Gallion, Londonderry .... Mica slate 1624 Slievemish, Antrim Basalt 1398 Sphell Cooagh, Londonderry . . . , 1867 Squire's Hill, Antrim 1 170 Teabuliagh, Antrim Basalt on Chalk . 1235 Three Rock Mountain, Wicklow . Granite 1585 Tonelagee 2696 West Aston Hills, Wicklozo Clay si. & Granite 1000 FINIS. London: printed by William Phillips, George Yard. Lombard Street, THIS BOOK IS DUE ON THE LAST DATE STAMPED BELOW BOOKS REQUESTED BY ANOTHER BORROWER ARE SUBJECT TO RECALL AFTER ONE WEEK. RENEWED BOOKS ARE SUBJECT TO IMMEDIATE RECALL LIBRARY, UNIVERSITY OF CALIFORNIA, DAVIS Book Slip-Series 458 QV Phillips, William, 1775-1828. 2.152303 363 Outlines of mineralogy and geology, comprehending the PU elements of those sciences; intended principally for the u*e of young persons. 4th eil., enl. By William Phillips ... London, Printed and sold by W. Phillips, 1826. PHYSICAL xvl, 292 p. front , cllnffr*. 20-. SCIENCES LIBRARY %/l. Minen.Iogy.^. Geology. VI. Title. p/pak/sac ^/?6 ^^ U S. Geol. survey. I.ihn. > /^tHPMTUS fr Library of (%>ngr>k ij ,