OF EDUCASIOS G. S WHITFORD. THE SCIENTIFIC CLASS-BOOK; OR, A FAMILIAR INTRODUCTION TO THE PRINCIPLES OF PHYSICAL SCIENCE, FOR THE USE OF SCHOOLS AND ACADEMIES. ON THE BASIS OF MR. J. M. MOFFATT. PART II. COMPRISING CHEMISTRY, METALLURGY, MINERALOGY, CRYSTALLOGRAPHY, GEOLOGY, ORYCTOLOGY, AND METEOROLOGY. WITH ADDITION'S, EMENDATIONS, NOTES, REFERENCES, QUESTIONS FOR EXAMINATION, LISTS OF WORKS RELATING TO THE SEVERAL SUBJECTS, SOME ADDITIONAL ILLUSTRATIONS, AND A COPIOUS INDEX. BY WALTER R. JOHNSON, A.M. Professor of Mechanics and Natural Philosophy in the Franklin Institute of the State of Pennsylvania, Member of the Academy of Natural Sciences of Philadelphia, and one of the Vice Presidents of the American Institute of Instruction. PHILADELPHIA : PUBLISHED BY KEY AND BIDDLE. 1836. ENTERED according to Act of Congress, in the year 1836, by KEY & DIDDLE, in the Clerk's Office of the District Court of the Eastern District of Pennsylvania. EDUCATION LIBS. STEREOTYPED BY L.JOHNSON, PHILADELPHIA. . CONTENTS. CHEMISTRY. Definition, 9 Objects of the Science, ib. Attraction of Aggregation and Attraction of Composition, 9 Modes of Aggregation, 10 Effect of Chemical Combination, 12 Simple and Compound Substances, 14 Table of Simple Substances, 16 Oxygen, 18 Nitrogen, 18 Hydrogen, 19 Chlorine, 20 Carbon, 21 Silicon, ib. Boron, Sulphur, Phosphorous, 22 Iodine, Bromine, Fluorine, 23 Selenium, 24 Metals, ib. Chemical Affinity, 26 Laws of Chemical Affinity, 27 Elective Attraction, 28 Divisibility of Matter, 29 Combustion, 34 Influence of Heat on Solution, 38 Electricity, 40 Metallic Crystallizations, 46 Animal Electricity, 48 Spontaneous Combustion of the Human Body, 49 Theory of Definite Proportions, 52 Atomic Weights of Bodies, 53 Dr. Wollaston's Scale of Equivalents, 57 Simple and Compound Elective Attraction, 62 Primary and Secondary Chemical Compounds, 66 Observations on Simple Bodies and their Primary Compounds, 69 Table of Binary Compounds of Non- metallic Elements, 70 Oxygen, Oxides, and Acids, 73 Chlorine and Chlorides, 78 Iodine, lodic Acid, 81 Bromine, Bromic Acid, 83,84 Fluorine, 85 Hydrogen, 87 Water, 88 Muriatic Acid, 92 Nitrogen, 95 Oxides of Nitrogen, 96 Acids, 98 Chloride of Nitrogen, 99 Ammonia, 100 Carbon, Diamond, 101 Carbonic Oxide, 103 Acids, ib. Compounds of Hydrogen and Carbon, 109 Cyanogen, 112 Boron, Boracic Acid, 113, 114 Silicon, 116 Silica, 117 Phosphorus, 119 Oxides and Acids, 121 Combinations with Hydrogen, 124 Sulphur, 126 Acids, 127 Sulphurets, 131 Selenium, 132 Acids, 133 Metallic Elements, 134 Classification of Metals, 136 Tables of Binary Combinations of Metallic and Non- metallic Elements, 137, 138, 139 Arsenic, 139 Antimony, Columbium, Titanium, 140 Chrome, Molybdena, Tellurium, Tungsten, .141 Vana- dium, Uranium, Manganese, 142 Cobalt, Tin, 143 Potassium, 145 So- dium, 147 Lithium, 148 Baryum, 149 Calcium, Strontium, 150 Mag- nesium, 151 Aluminum, Zirconium, 152 Glucinum, Yttrium, Thorinum, 153 Iron, 156 Nickel, Zinc, Cadmium, Cerium, 157 Lead, Copper, Bis- muth, 158 Mercury, Silver, Gold, 159 Platina, Palladium, Rhodium, Iridium, Osmium, and Analysis, 160 Analysis of Earths and Stones, 161 Vegetable Kingdom, 164 Analysis of Vegetables, 167 Animal King- dom, 168 Soils, 170 Analysis of Soils, 172 Mineral Waters, 176 Testing of Mineral Waters, 177 Works on Chemistry, 185. METALLURGY. Definition, 186 Mineral Deposits and Mines, 187 Mineral Veins, 188 Metallic Ores and their Localities, 193-196 Art of Mining, 196- 209 Docimacy, 209 Assaying by the Dry Method, 210 Assaying by the Moist Method, 213 Reduction of Metallic Ores, 215 Gold, 216 Silver, 218 Platina, 219 Mercury, 220 Iron, 221 Tin. 225 Copper, 226 Lead, 228 Zinc, 229 Alloys, 231 Works on Metallurgy, 235. MINERALOGY. Preliminary Observations, 236 Classification of Minerals, 237 Proper- ties of Minerals, 238 Constituents of Mineral Substances, 243 Arrange- ment, 244 Table of Mineral Classes, 246 Elettro-positive Native Metals, 249 Electro-negative Substances and their Non-oxidized Combinations, JVJ5 l 770fiO CONTENTS. 249 Tellurium and Tellurets, ib. Arsenic and Arseniurets, 250 Carbon and Carburets, ib. Selenium and Seleniurets, 251 Sulphur and Sulphu- rets, 252 Oxides of Electro-positive Metals, 256 Oxides and Oxacids of Electro-negative Substances, 258 Alumina and Aluminates, ib. Silica and Silicates, 258, 261 oxide of Titanium and Titanates, 267 Columbia Acid and Columbates, 268 Antimonic Acid and Antimoniates, ib. Tung- states, ib. Molybdic Acid and Molybdates, 269 Chromic Acid and Chromates, ib. Vanadic Acid and Vanadiates, 270 Boracic Acid and Bo- rates, ib. Carbonates, 271 Arsenious Acid and Arseniates, 275 Phos- phates, 276 Nitrates, 277 Sulphates, ib. Fluorides, 279 Chlorides, 280 Organo-chemical Substances, 281 Works on Mineralogy, 282. CRYSTALLOGRAPHY. Figures of Crystals, 284 Isomorphism, 285 Haiiy's Theory of Crystal- lization, 288 Primitive Forms, 290 Law of Decrements, 293 Goniome- try, 295 Crystallometrical System of Mohs, 296 Works on Crystallo- graphy, 297. GEOLOGY. Introductory Remarks, 298 Cosmogonical Speculations, 299 Theories of Werner and Hutton, 300 Researches of Cuvier, 302 Progress of Geo- logical Science, 303 Figure of the Earth, 304 Density, 305 Specula- tions on the Central Structure of the Earth, 306 Subterranean Tempera- ture, 308 Thermal Springs, 312 Temperature of the Atmosphere, 315 State of the Earth's Surface, 317 State of the Crust of the Earth, 318 Modifying Action of Existing Causes, 319 Influence of the Atmosphere, 324 Deluges of Sand, 333 Hurricanes, 334 Influence of Water, 336 Destructive Effects, ib. Land -floods, 339 Alluvial Islands, 340 Deba- cles, 342 Landslips, 345 Bursting of Bogs and Mosses, 346 Action of Frozen Water, 348 Effect of Waves and Breakers, 349 Deposits from Hot Springs, 351 Submarine Formations, 353 Earthquakes, 357 Vol- canos, 361 Causes of these Phenomena, 367 Remarks on the Analogy between Ancient and Modern Disturbances of the Earth's Surface, 368 Formation of Valleys, 373 Erratic Blocks, 375 Elevation of Mountains, 377 Mineral Structure of Rocks, 380 Mechanical Structure, 385 Clas- sification and Arrangement of Rocks, 391 Table of Groups, Formations, and Rocks, 393 Works on Geology, 397. ORYCTOLOGY. Modes of Fossilization, 400 Geological Arrangement of Minerals and Fossils, 405 Primordial Rocks and their Minerals, 407 Fossil Remains in Submedial Rocks, 409 in Medial Rocks, 412 in Supermedial Rocks, 419 in Tertiary Rocks, 426 in Alluvial Deposits and Bone Caverns, 428 Oryctology of the United States, 433 Works on Oryctology, 435. METEOROLOGY. Preliminary Remarks, 436 General Observations on the Atmosphere, 437 Variations of Atmospheric Pressure, 439 Winds, 440 Causes of Winds, 441 Periodical, Variable, and Local Winds, 443 Velocity of Winds, 445 Hygrometry, 446 Saussure's Hygrometer, 448 Darnell's and other Dew-point Hygrometers, 449, 450 Clouds, 450 Formation, 451 Constitution, 452 Modifications, 453 Cirrus, 454, Cumulus, 455. Stra- tus, ib. Cirrocumulus, 456 Cirrostratus, ib. Cumulostratus, 457 Nim- bus, ib. Rain, ib. Snow, 458 Hail, 459 Dew, 460 Hoar-frost, 461 Ground-ice, 462 Optical and Electrical Phenomena, 463 Aerolites, ib. Works on Meteorology 464. PREFACE. THE same reasons which impelled us to undertake the adaptation of the first part of the " Scientific Class Book" to the use of schools and academies in the United States, has equally, or even more forcibly, urged the importance of performing the like task in regard to the present work. In several of the departments in- cluded in this volume, we have hitherto been so far from possessing a good treatise adapted to schools, that we have, in fact, had no work in all respects eligible as a text book, even for the highest institutions. This deficiency cannot be said to arise from a want of interest to create a demand for information in regard to the sciences here sketched. The remarkable ra- pidity with which the arts, dependent for their success on these divisions of knowledge, have recently ad- vanced, evinces that high national interests are con- cerned in the diffusion of correct notions respecting their phenomena and laws. The treatise on Chemistry will be found to contain a general discussion of the objects of the science, a concise view of the various simple substances of which it treats, and the chemical laws of combination, together with a brief account of the non-metallic and the metallic ele- ments, and their respective compounds. We have added a considerable number of illustrations; and ar- ranged and condensed, from the excellent Chemical Dic- tionary of Dr. Ure, the articles on analysis of stones on the vegetable creation, its chemical constituents, and modes of analysis on the animal kingdom and its che- mical relations on the nature of soils, with the methods of testing and improving their character, as detailed by Davy and others, and on the constitutions and tests of A2 5 6 PREFACE. mineral waters. Without these additions the treatise on Chemistry would haye lacked much of its value as a practical elementary guide. With these, the usefulness of the science is at once made manifest, and the methods of operating, presented in the subsequent parts, in which the treatment of metallic ores and other minerals is described, become intelligible and of easy application. The nomenclature employed in this department, is in accordance with the usage of the most approved modern writers. The tract on Metallurgy will, it is confidently be- lieved, be found to embrace a highly useful series of elementary facts and instructions, upon a department of science and art rapidly rising in the estimation of the community, and upon which hitherto very little general information has been diffused. The subdivisions of this treatise, relating to mineral veins and mines the art of mining, and that of assaying by mechanical means, and by the dry and humid methods respect- ively the metallurgic processes for reducing ores, with the methods of forming alloys, and the uses to which the latter are severally applied, form so many highly curious and interesting topics of discussion, adapted alike to stimulate and to reward inquiry. Among the branches of knowledge which now engage the intense interest of the scientific world, one of the most attractive is that which relates to the present state of the earth's surface, and to the crust immediately beneath it. This science involves the necessity of understanding the phenomena and principles of chemistry, not less than those of mineralogy and the laws of crystalliza- tion; and it leads directly to the development of those remarkable truths respecting the former condition and inhabitants of our planet, which the study of fossil geology could alone impart. The freshness of these subjects to the minds of American students, the facility of illustrating them in all their details by the observa- tion of numerous facts, and the influence of those dis- tinguished names among ourselves, who have become connected with the cultivation of these several sciences, PREFACE. 7 and to whose works we have made frequent reference, will, it is believed, insure to these treatises the attention which their subjects must ever strongly invite. However remote may seem, upon a limited view, the connection between the study of such subjects as that of organic remains, and the direct usefulness of its results, yet when it is recollected that the very nature of rocks, the value of minerals which may be expected to accompany them, and the soils they may aid in pro- ducing, are all indicated by the kinds of organic remains found in such rocks, it will be apparent that most useful knowledge may be derived from this study. In works of science the style is a matter entirely secondary in its relation to the truths of nature deve- loped. Studied graces, and especially ambitious orna- ments of mere rhetoric, would, by every votary of science, be felt to be misplaced. Neatness and perspi- cuity are the chief characteristics which such a treatise demands; and these, it is conceived, have been ade- quately preserved, maintaining constantly a due regard to the great purpose of rendering the work intelligible to the young, without offending the taste of the more mature. In preparing the questions for exercising the learner, the same view has been maintained which guided our labours in the first part of this work. We are far from con- sidering questions unimportant, whether we regard them in reference to classes in schools, to family circles, or to private students. The chief inquiry, in relation to their usefulness, seems to be, whether they are such as a well qualified teacher, familiar with his subject, would propose to his scholars. We leave competent persons in the profession to answer the inquiry, with regard to this division of our labour; merely premising, that though a vast majority of teachers probably prefer works fur- nished with this subsidiary to their instructions, yet that such as may deem their own questions more appropriate, or more intelligible to their pupils, than those of the editor, will not lie under any necessity of resorting to these; and it is certainly anticipated that 8 PREFACE. none will content themselves with the exclusive use of the latter. Very many of the questions are designed merely to furnish topics arising out of important truths or suggestions contained in the text, on which the familiar dissertations of the teacher may be founded; and if he avail himself of the works named at the end of each treatise, his oral explanations will possess a freshness and interest more captivating to the scholar than the pages of any volume, however learned or well written. The distinguished favour with which teachers have received the first part of the " Scientific Class Book," has stimulated us to endeavour, and encouraged us to hope, that the present volume may not be found less worthy than its predecessor, of their regard and accept- ance. CHEMISTRY. 1. CHEMISTRY is the art whereby compound bodies are changed into simple ones, or simple ones into compounds. The former of these processes is called Analysis or Decomposition, and the lat- ter Synthesis or Composition. As a science, it is the province of Chemistry to determine the chemical relation of simple bodies, and the structure and chemical relations of compounds. Few of the operations of Chemistry, which are employed for the attainment of these objects, are either purely analytic or syn- thetic ; a combination of these methods generally taking place in the processes of the chemist. 2. Different kinds of matter which are the objects of Chemistry, possess certain active properties, such as gravity or weight, cohesion, elasticity, expansibility, magnetic attraction, &c. All these properties are but so many different modifications of attrac- tion and repulsion. Action, either attractive or repulsive, takes place between bodies situated at various distances from each other. Thus the attraction of gravitation operates at indefinite and immense distances ; while the attraction of cohesion affects the particles of bodies only when placed in apparent contact. Repulsive action also takes place at different distances. Thus tha repulsion between bodies which have been subjected to the in- fluence of electricity or magnetism is sufficiently obvious to the sight ; and that electric or magnetic substances which repel each other do not touch, may easily be perceived. The expansive power of heat, on the other hand, probably affects particles of matter nearly in contact with each other. 3. The various phenomena which constitute the objects of Che- mistry, depend on the operation of those modifications of attrac- tive and repulsive force, which act on particles of bodies placed at insensible distances from each other, and are so minute as not to he cognizable by our senses, even when asssisted by the most powerful magnifying glasses. 4. There are two species of attraction which affect particles of matter when in apparent contact : 1. The Attraction of Aggrega- tion, or Cohesion ; 2. The Attraction of Composition. These What is the office of chemistry, considered as an art ? How extensive is its province as a science ? By what two methods are its purposes effected ? What are some of the active properties of matter by which its chemical changes are produced ? What is the true nature of these properties ? What is the difference between gravitation and cohesive attraction? Under what different circumstances is the repulsive action of bodies exercised ? On which modification of attractive and repulsive forces do chemical changes depend ? How many kinds of contiguous attraction exist in matter ? 9 10 CHEMISTRY. powers both give way to the repulsive action of heat r'but the for- mer may also be overcome by mechanical force, which has no ef- fect on the latter. 5. The Attraction of Aggregation operates differently on different bodies, so as to produce the various degrees of cohesive force or consistence observable among them. The forms under which bo- dies appear are reducible to three classes, viz. : Solids, Liquids, and Gases or Airs. These modifications of matter are influenced by the operation of mechanical pressure, and the expansive force ot heat, which seem to act as antagonist powers to each other. Some kinds of matter are capable of existing either in a solid, li- quid, or gaseous state, under different degrees of atmospherical pressure and temperature. Thus water, by the abstraction of heat, becomes changed to ice ; by the addition of heat, it is, on the other hand, changed to vapour ; and that change is facilitated or impeded by lessening or increasing the atmospherical pressure. Mercury and several other substances exhibit analogous phenomena. 6. Many bodies, however, commonly exist under only one or two forms of aggregation. Common air and other bodies, distin- guished from vapours by the designation of permanent gases, were formerly supposed to retain the gaseous forms under all circum- stances ; but, from the experiments of Dr. Faraday and Mr. Per- kins, it appears that atmospheric air, carburetted hydrogen, sul- phuretted hydrogen, sulphurous acid, carbonic acid, protoxide of chlorine, nitrous oxide, cyanogen, ammonia, muriatic acid, and chlorine, all which, under common temperature and pressures, are permanent gases, may be condensed to the liquid state by the ioint operation of intense cold and powerful compression. How- ever, oxygen, hydrogen, and some other gases have hitherto re- sisted all attempts to reduce them to the liquid state.* Several dense solids, as lead and glass, are readily melted by heat ; but there are others, as wood, which, though speedily decomposed, when heated with access of air, cannot be liquefied. The facts already stated, and others which might be adduced, still lead to the conclusion, that the solid, liquid, and gaseous states of bodies depend chiefly on their respective relations to temperature and pressure ; and therefore the distinctions founded on those states or forms of matter do not furnish sufficient grounds for general ar- rangements of bodies in separate classes. Which of these is overcome by mechanical means ? By what causes are the three forms of matter chiefly influenced ? Give some examples of variable forms in matter. What changes of form may be mentioned as solely due to the effect of caloric ? In what instances does the chemical change of solids take place without liquefaction ? To what causes are we hence led to refer the several changes in the forms of matter ? * See Scientific Class Book, pt i. p. 180. FORMS OF BODIES. 11 '',. Some writers have treated of the chemical properties of gases or airs as an independent branch of science, under the appellation of Aerology; but the operation of bodies under their different forms are so intimately blended, and the condensation of gases is so commonly the effect of chemical combinations, that it seems by farjnost convenient not to separate Aerology from Chemistry, but to regard it as a subordinate section or subdivision of chemical science. 8. In solid and liquid substances, the powers of attraction and re- pulsion counterbalance each other ; while the latter predominates in gaseous bodies. Some have supposed solidity to result from the preponderance of the force of attraction over the force of repul- sion ; but this opinion seems incompatible with the well-known fact of the expansion of water when it becomes solid. This and some other phenomena of a similar description, clearly show that the action of a repulsive force is not less obvious in solids than in fluids. They probably differ more in the arrangement of their particles, than in the manner in which those particles are united. 9. The peculiar province of Chemistry, as might be inferred from the preceding observations, is the study of the Attraction of Composition, or the investigation of the properties of bodies, not as respects their organization, mechanical construction, form, or consistence, but with a view to the discovery of their molecular composition, or the nature and mode of union of their component particles. Hence there must necessarily be a wide distinction between mechanical and chemical combination. Any substances may be mechanically combined by mere mixture, which occasions no destruction or essential alteration of the sensible properties of the mixed bodies : for the compound formed by the union of two or more substances which have no chemical action on each other, will always exhibit their joint properties, modified, perhaps, but not destroyed by their commixture. The effect of chemical com- bination is very different, for bodies chemically united often become completely deprived of the peculiar properties they previously possessed, and manifest new and sometimes very ex- traordinary powers, totally different from those of their constituent parts. 10. " If water be added to water, or salt to salt, the effect is an increase of quantity, but no change of quality. In this case, the mutual action of the particles is entirely mechanical. Again, if a blue powder and a yellow one, each perfectly dry, be mixed and well shaken together, a green powder will be produced ; but this is a mere effect arising in the eye, from the intimate mixture of In what relation to chemistry may we properly consider the department of aerology ? Why ? What are the relative intensities of attraction and of repulsion in solids, liquids, and aeriform bodies? What is the peculiar province of chemistry ? What is the most important difference between bodies mechanically mixed and those chemically combined ? 12 CHEMISTRY. the yellow and blue light, separately and independently reflected from the minute particles of each ; and the proof is had by exa- mining the mixture with a microscope, when the yellow and blue grains will be seen separate, and each quite unaltered. If the same experiment be tried with coloured liquids, which are sus- ceptible of mixing without chemical action, a compound colour is likewise produced, but no examination with magnifiers is in that case sufficient to detect the ingredients; the reason obviously be- ing, the excessive minuteness of the parts, and their perfect inter- mixture, produced by agitating two liquids together. 11. "From the mixture of two powders, extreme patience would enable any one, by picking out with a magnifier grain after grain, to separate the ingredients. But when liquids are mixed, no mechanical separation is any longer practicable ; the particles are so minute as to elude all search. Yet this does not hinder us from regarding such a compound as still a mere mixture, and its properties are accordingly intermediate between those of the li- quids mixed. But this is far from being the case with all liquids. 12. " When a solution of potash, for example, and another of tartaric acid, each perfectly liquid, are mixed together in proper proportions, a great quantity of solid saline substance falls to the bottom of the containing vessel, which is quite different from pot- ash or tartaric acid, and the liquid from which it subsided offers no indications by its taste or other sensible qualities of the ingre- dients mixed, but of something totally different from either. It is evident that this is a phenomenon widely different from that of mere mixture ; there has taken place a great and radical change in the intimate nature of the ingredients, by which a new sub- stance is produced which had no existence before ; and it has been produced by the union of the ingredients presented to each other, for when examined, it is found that nothing has been lost, the weight of the whole mixture being the sum of the weights mixed. Yet the potash and the tartaric acid have disappeared entirely, and the weight of the new product is found to be exactly equal to that of the tartaric acid and potash employed, taken together, abating a small portion held in solution in the liquid, which may be obtained however by evaporation. They have therefore com- bined, and adhere to one another with a cohesive force sufficient to form a solid out of a liquid ; a force which has been called into action by merely presenting them to each other in a state of solu- tion."* How does it appear that blue and yellow powders, producing a green mixture retain their respective qualities ? In what respect does the case of two coloured liquids, susceptible only of mixture, and not of chemical composition, differ from that of two pow- ders? Give an example of an entire change of properties in two liquids by their mutual actions when mixed together. * Hersehell's Discourse on the Study of Natural Philosophy, pp 297, 298. MODERN DISCO VEIES. 13 13. As it is the object of Chemistry to determine the composition of different substances, therefore if we could reduce all bodies to their elementary principles, and discover the proportions in which these principles must be combined in order to recompose such bo- dies, the science of Chemistry would be complete. This, how- ever, is far from being the case, notwithstanding the extraordinary discoveries that have rewarded the labours of those philosophers who have paid attention to this important branch of knowledge. 14. But though we allow that much remains to be achieved by future experimentalists ere Chemistry can be said to make any near approaches to perfection, yet it must be admitted, that the improvements which have taken place in this science in our own times are of no common importance, since its first principles have been fixed on the firm basis of experiment, and a luminous sys- tem, founded on facts, has superseded those obscure and hypo- thetical speculations which occur in the writings of the older chemical authors. 15. Among the most important discoveries of modern philoso- phers, we may reckon those which relate to that inherent ten- dency which matter possesses to form new combinations. This property of matter gives rise to many of those operations of nature which we view without surprise, only because they are common ; and it is not less concerned in several of the most striking and ex- traordinary phenomena of nature and art. Thus when we procure light or heat by burning any combustible substance, as for instance wood, chemical action takes place between the inflammable mat- ter contained in the wood, and part of the air of the room in which the wood is burned ; in consequence of which, a new kind of air is formed, the greater part of which flies off with the smoke. The respiration of animals affords another instance of chemical action. When air is taken into the lungs, a part of it combines with something which separates from the blood ; in conse- quence of which combination, the air becomes altered in its properties, as must be obvious to every one who considers that the atmosphere of a crowded apartment, not properly venti- lated, is soon rendered so noxious as to occasion considerable inconvenience, and even faintness, to those whose constitutions are delicate. 16. On taking a survey of the various bodies around us, we may observe, that some among them, which we reckon inert, be- cause from the influence of habit or oth in England; and 7 1774 Scheele, in Sweden ... S 2 Chlorine .... Scheele, in Sweden 1774 3 Iodine Courtois, in France 1811 4 Bromine .... Balard, in France 1826 f" Properties first accurately investi- 5 Fluorine . . . < gated by Scheele; but it has never C. been exhibited in a separate state. 6 Hydrogen . . . Cavendish, in England .... 1766 7 Nitrogen ... Dr. D. Rutherford, in Scotland . 1772 8 Carbon 9 Boron Sir H. Davy, in England . . . 1807 10 Silicon .... Berzelius, in Sweden .... 1824 11 Phosphorus . . Brandt, at Hamburgh .... 1669 12 Sulphur 13 Selenium . . . Berzelius, in Sweden .... 1818 Into how many and what divisions are simple bodies at present distin guished? What is the number of non-metallic elements ? By whom and at what period was the existence of oxygen discovered ? Bromine ? Chlorine ? Iodine ? Nitrogen ? Who investigated the properties of fluorine? Who discovered hydrogen ? Carbon ? Boron ? Silicon ? Phosphorus 1 Selenium ? TABLE OF SIMPLE SUBSTANCES. 14 Potassium , 15 Sodium . . 16 Lithium . . 17 Baryum . . 18 Strontium . 19 Calcium . . 20 Magnesium 21 Aluminum . 22 Glucinum . 23 Yttrium . . 24 Zirconium . 25 Thorium . . 26 Cerium . . 27 Tellurium . 28 Arsenic . . 29 Antimony . 30 Chromium . 31 Vanadium . , 32 Uranium 33 Molybdenum 34 Tungsten . , 35 Columbium . 36 Titanium , 37 Iron .... 38 Manganese 39 Nickel . , 40 Cobalt . . , 41 Zinc .... 42 Cadmium . 43 Lead . . . 44 "Tin 45 Copper . . Discoverers. II. Metals. H. Davy, in England Date of Discovery 1807 f C Oxide discovered by Arfvedson, in ") 1Q1Q 1 Sweden . . ' . . . . j 1818 Sir H. Davy, in England . . . 1808 . Bussy, in France 1829 . Wohler, in Germany 1828 C Oxide discovered by Vauquelin, in "> ( France $ C Oxide discovered by Gadolin, in } Sweden j , Berzelius, in Sweden 1824 . Berzelius , Mosander, in Sweden .... 1804 Klaproth, at Berlin 1797 T Appears to have been known to"^ Paracelsus, in the 16th century; it^o-* but first accurately examined by j ' Geo. Brandt, in Sweden . . J . Known to Basil Valentine . about 1450 . Vauquelin, in France .... 1797 . Sefstrom and Berzelius, in Sweden 1830 . Klaproth, at Berlin 1789 rScheele, in Sweden 1778 < Reduced to the metallic state by 7 i^o- ( Hielm S . MM. D'Elhuyarts, in Spain . . 1781 ("Oxide discovered by Hatchett, in ^ J England; and by Ekeberg, in C 1801 ) Sweden J LReduced by Berzelius .... 1824 . Vauquelin, in France .... 1796 . Known from time immemorial . Gahn, in Sweden 1774 . Bergman, in Sweden 1775 . Brandt, in Sweden 1733 . Henckel mentions its reduction in 1791 . Stromeyer in Germany .... 1817 . Known from time immemorial, Do. Do. What metallic bodies have been discovered by Sir. H. Davy ? By what philosopher was aluminum discovered ? How early was arsenic known ? Which of the metals have been known from the earliest ages of history ? IIo\v lung has zinc been known as a rlitinct metal ? B2 18 CHEMISTRY. Discoverer, 46 Bismuth .... Mentioned by Geo. Agricola about 1530 47 Mercury .... Known from time immemorial. 48 Silver ..... Do. 49 Gold ..... Do. 50 Platina . . . ^** Assay-master 51 Palladium ... Dr. Wollaston, in England . . . 1803 52 Rhodium . . . The same ........ 1804 54 Osmium ::: } Tenant, in England ..... 1803 27. As some of these elementary bodies enter into the composi- tion of a vast variety of substances of common occurrence, and as it is impossible intelligibly to describe chemical pbenomena without the frequent mention of them, or allusion to their proper- ties and modes of action, some short notices of them may here be advantageously introduced, previously to a review of the laws of chemical affinity, and a more extensive description of the simple bodies in general, and of the most important compounds arising from their relative action upon each other. We shall thus avoid the necessity of repeated explanations of the nature of these bodies each time they are mentioned, or the still greater inconvenience of referring to the properties and effects of substances with which the reader may be supposed to be unacquainted. 28. Among the thirteen non-metallic elements there are some which at all common temperatures exist only in the gaseous state, while the others at moderately low temperatures are solids. The first and most important of the elementary bodies is that called OXYGEN, from two Greek words, denoting the power of producing acids, because it was formerly thought to be the universal acidify- ing principle, though it is now known that there are many acids in which oxygen is not contained. One of the grand characteris- tic properties of this gaseous element is that of being a most powerful supporter of combustion, so that most inflammable bodies burn in it rapidly and brilliantly. Its more peculiar pro- perties will be subsequently described ; and we shall only add here that it unites with all other elementary substances (except possibly fluorine), and with many of them in various proportions. 29. NITROGEN OR AZOTE is also a gaseous body, the mixture of which with oxygen in certain proportions constitutes atmospheric or common air. The name azote, derived from the Greek, im- plies its being improper for the purpose of respiration, as animals confined in this gas soon die. It is therefore owing to the oxygen By whom and at what period was platina discovered ? In what two states do the non-metallic bodies exist ? What is the origin of the term oxygen ? What is one of the characteristic properties of oxygen ? How extensive is its power of combining with other elementary bodies ? In what state does nitrogen exist ? Into what well known fluid does it enter as a constituent ? Why is it called azote ? Whence is the term nitrogen derived ! CHLORINE. containedjn atmospheric air that it is capable of supporth,^ life, for none of the higher classes of animals can exist longv^ kind of air which does not contain oxygen. 30. The term Nitrogen has been applied to the gas now undeV' notice, in consequence of its being found to be a constituent part of 'nitric acid, or as it is vulgarly called, aqua fortis, which is a chemical compound containing a very large proportion of oxygen united to the nitrogen. There are also other compounds of oxygen with nitrogen, among which may be mentioned that sometimes called nitrous oxide, and which, though it contains more oxygen than atmospheric air, may yet be breathed for a time with safety; but it produces very remarkable effects when thus used, generally occasioning a state of excitement somewhat similar to that caused by drinking wine or spirits, and hence it has been popularly named intoxicating or laughing gas. Nitrogen enters largely into the composition of most kinds of animal matter. 31. HYDROGEN is likewise a gas, being that which when combined with oxygen forms water, as its name, which is derived from the Greek, implies. .It was, when first discovered, called phlogiston, and inflammable air. The former of these terms was attached to it in consequence of an erroneous opinion, at one period generally adopted by chemists, that all metals were com- posed of various kinds of calces or earths, each respectively united to an inflammable principle named phlogiston. Now as it was observed that when any metal becomes dissolved in a diluted acid, as when iron or zinc are thus treated with sulphuric acid and water, inflammable air was always given off during the process, it was conjectured that the air in question was derived from the metal ; though it is now known that, in the case pro- posed, it arises from the decomposition of the water with which the acid is diluted, and that this sort of air never makes its appearance in the course of such metallic solutions, unless water or some other body containing hydrogen be present. This gas, though highly inflammable when mixed with oxygen, and some other simple and compound gases, yet is incapable of supporting combustion, for if a burning body, as a lighted candle or match, be introduced into it, the flame will be immediately extinguished. 32. Hydrogen enters into combination with most other sub- stances, producing many remarkable compounds, among which may be mentioned that formed by its union with nitrogen ; the result of which-ls an alkaline gas, formerly called volatile alkali, In what other form besides that of atmospheric air may nitrogen be inhaled ? Into what class of organised bodies does nitrogen enter ? What is the meaning of the word hydrogen ? By what name was it called at the time of its discovery From what error did this application of the name phlogiston proceed ? What more recent observation has enabled chemists to correct the error ? What is the power of hydrogen in regard to combustion? 'SO CHEMISTRY. and now ammonia. This compound which at common tempera- tures exists only in the state of gas, is rapidly absorbed by water or spirit of wine, communicating to it a peculiar pungent odour, with which most persons are familiar, as belonging to spirit of hartshorn and smelling salts. 33. CHLORINK is the last of the simple bodies existing in a gaseous state at common temperatures ; but, while those already mentioned are not only transparent but colourless, this gas exhibits a yellow- ish-green tint, whence its name chlorine.* 'It was originally ob- tained, by Scheele, from the decomposition of muriatic acid, or spirit of salt, in which he found it combined with hydrogen, then called phlogiston ; and therefore he gave to the newly-obtained gas the name^ of dephlogisticated marine acid." It was subse- quently supposed to be a compound of muriatic acid, and oxygen ^ but Sir H. Davy ascertained its real nature, and gave it its present name. 34. Chlorine unites with many other simple and compound bodies, forming with several of them acids; and in other respects it exhibits chemical properties analogous to those of oxygen, being like that gas a supporter of combustion. It is largely dis- persed throughout nature, but always in a state of combination, as in sea-water and rock-salt, or that procured from brine springs, in which it is united with the metal sodium. This gas is by no means adapted for respiration, and when mixed with much atmos- pheric air it still proves highly irritating, provoking cough and defluxion from the nostrils. As it combines rapidly with many other gases, it has been found useful to purify air loaded with infectious miasmata. It is on this account that the chloride of lime, in solution, is used to sprinkle the floors and walls, of rooms, and to purify clothes and other articles, which have been tainted by putrid or infectious vapours. Chlorine has also a powerful effect in destroying vegetable colours, and the chloride of lime is therefore extensively used in the process of bleaching linen cloth and other substances. 35. The four preceding bodies, oxygen, hydrogen, nitrogen, and chlorine, exist at common temperatures and pressures only What may be mentioned as among the remarkable compounds of hy- drogen ? By what properties is that compound familiarly known ? What method was employed by Scheele for procuring chlorine ? What name did he apply to it I What was afterwards supposed to be its nature ? Who investigated its character and gave it the present name ? What properties does it exhibit in common with oxygen ? How does chlorine exist in nature ? What are among its remarkable properties ? * Chlore in French, from the Greek %^s, the green colour of young herbage. .. SILICON. 2J as gas. There are other suhstances, as, for instance, carbon (charcoal), and the more rare bodies, called silicon and boron, which are found only in the solid state; and some, like iron and most of the metals, though usually solid, become liquefied at respectively various temperatures ; and there is still another class of bodies capable of existing under the three several forms of aggregation. Among these last are sulphur, phosphorus, and the substances called bromine, iodine, and selenium, which are of less frequent occurrence. 36. CARBON is a solid body, hitherto undecomposed and there- fore supposed to be elementary, which enters largely into the composition of most substances belonging to the animal and vege- table kingdoms, and which also forms the basis of many of the combustible minerals, as bitumen, coal, plumbago, and amber. In the form of charcoal, procured by charring, or distilling with- out the access of air, wood and some other substances, carbon is obtained in a separate state, or merely intermixed with small portions of earths or salts ; and it exists in a state of the greatest purity in the diamond ; for it has been ascertained by chemical investigation, that the diamond, when exposed to a very high temperature, and especially if confined in oxygen gas, will burn like charcoal, exhibiting the same product ; that gem consisting entirely of crystallized carbon. 37. With most of the simple substances carbon constitutes a variety of compounds, among the most important of which are those arising from its union with oxygen, with which it forms both an oxide and an acid : the latter, called carbonic acid, is the gaseous body formerly known by the name of fixed air, which is abundantly produced in the combustion of vegetable matter, in the respiration of animals, and in other processes. In conse- quence of its strong affinity for oxygen, carbon, or rather sub- stances containing it, are generally used for the purpose of reduc- ing iron and other metals from their ores, in which they are frequently combined with oxygen. The combinations of this body with hydrogen are extremely numerous, forming the bases, of vinous spirits, oils, resins and a great variety of other vegeta- ble products. 38. SILICON is never met with in nature in an uncombined state, What three substances have been separately procured only in the solid state ? What substances assume all the three forms of matter under different circumstances ? fn how many departments of nature is carbon distributed ? In what form does it exist in the greatest purity ? How is this proved ? What different compounds does it form with oxygen ? By what name was carbonic acid formerly known ? Why is carbon used in the process of smelting metallic ores? What are some of the compounds of carbon with hydrogen ? How is silicon found in nature ? CHEMISTRY. but by its union with oxygen it forms silica, or siliceous earth, which in the various states of flint, quartz, rock crystal, and other analogous bodies, is dispersed in great abundance throughout the mineral kingdom. This substance when pure is a dark brown powder, which when first discovered was supposed to be of a metallic nature ; but as it exhibits none of the lustre of a metal, and is a nonconductor of electricity, it has with propriety been placed in the class of non-metallic elementary bodies. It unites with several other substances, forming compounds, the most im- portant of which, next to the oxide of silicon, (silica,) is the pro- duct of its union with fluorine. 39. BORON is the basis of the acid called boracic acid, which in combination with soda or mineral alkali, produces the saline substance named borax,' frequently used both in medicine and the arts. Boron is an olive-brown powder, destitute of taste or smell, which enters into union with some of the metals and other elementary bodies ; but its combinations are of little importance, except that which it forms with oxygen (boracic acid.) 40. SULPHUR is one of the few elementary substances which are found in nature in an uncombined state ; and it also often occurs in union with other substances. It is met with in large quantities in the neighbourhood of volcanos ; and being produced abundant- ly in the island of Sicily, it is brought as an article of commerce from the Mediterranean. This substance, hitherto undecomposed, and therefore regarded as elementary, occurs in two forms, that of a light yellow powder called flowers of sulphur, and that of a compact solid of a greenish-straw colour, sometimes called roll sulphur. The general properties of sulphur in both these forms are well known. 41. SULPHUR combines with most other bodies, forming a variety of compounds ; the most remarkable of which are those arising from its union with oxygen and hydrogen. It forms several oxides and acids, and one of the latter, sulphuric acid, oil of vitriol of commerce, is much used both alone and in combi- nation, for medical and technical purposes. With hydrogen, sul- phur forms a peculiar gas, which has some of the properties of an acid ; and which is given off during the putrefaction of animal substances, causing a peculiar offensive smell, resembling that of rotten eggs ; it was formerly called hepatic air. 42. PHOSPHORUS, like sulphur, is a solid but readily volatile substance ; but is never found in nature in an uncombined state. What are some of its compounds with oxygen ? What are some of the properties of silicon ? What are the distinguishing characters of boron? In what connexion with other substances is it usually seen in commerce ? How does sulphur exist in nature ? What are its most usual forms when prepared for the arts ? With what bodies does it Ibrm the most important of its compounds? By what name was sulphuretted hydrogen formerly known ? In what condition is phosphorus found in nature? FLUORINE. . 23 Some of its compounds occur occasionally in mineral substances , but it is most abundantly contained in certain animal fluids and solids, and especially in bone, from which it is usually obtained for experimental purposes. Phosphorus is found in the shops in the form of small cylinders,-semi-transparent, and nearly of the consistence of wax, internally of a reddish or flesh colour, but coated with a white film, arising from its partial decomposition. It so strongly attracts oxygen from the air as to become slowly decomposed at a very low temperature, and hence it is usually kept under water. . With oxygen it forms two acids, one of which, the phosphoric acid, In combination with lime or calcareous earth, constitutes the basis of bone./ It unites with hydrogen, to form an inflammable gas ;"" and it also enters into combination with various other bodies. 43. IODINE is a bluish-black or violet-coloured solid, having a metallic lustre. It is contained in sea-water, and in some marine productions, as seaweed and sponge ; and it is supposed that burnt sponge, which is used in medicine, owes its vi'rtues to the presence of iodine. This body, like oxygen and chlorine, is not itself combustible, but is a supporter of combustion. It unites with various other simple substances ; and with oxygen and chlorine,; it forms respectively acid compounds. 44. BROMINE, like iodine, is a marine production, and it is usually procured from the refuse liquor obtained in making sea salt. Its common form is that of a cloudy red liquid, having a very disagreeable smell and tase. It is one of the supporters of combustion, and enters into union with various simple bodies, forming acids both with oxygen and chlorine. In many respects, it bears a strong analogy to iodine, and has been supposed to be a compound of that body with chlorine ; but there appears to be sufficient evidence of its elementary nature. 45. FLUORINE is generally regarded as an elementary body, though it has never yet been exhibited in a separate state, in con- sequence of its powerful tendency to form combinations with all known substances.' Some of its compounds enter into the com- position of certain minerals, among which the best known is that called fluor spar, found in Derbyshire ; and which, from its beauty and the facility with which it may be cut and polished, is frequently used for making chimney ornaments and for other purposes. Among the artificial compounds of fluorine, one of From what source is it usually obtained ? In what form and consistence is it commonly found in commerce ? What are its important sensible properties ? Why is it usually kept under water ? With what other ingredients is it combined in the bones of animals ? What is the colour of iodine ? How is this substance related to the process of combustion ? With what 4 substances does it unite to form acids ? Why cannot fluorine be exhibited in a separate state ? In what natural bodies is it found ? 24 CHEMISTRY. the most important is that which it forms with hydrogen, called hydro-fluoric acid, which has the property of corroding glass. 46. SELENIUM is a reddish-gray solid, obtained from pyrites, and in many of its properties resembling sulphur, being like that body readily combustible. It has hitherto been found only in a few places, and in small quantities. It forms acids in combina- tion with oxygen ; and it also unites with hydrogen and chlorine, and probably with other elementary substances. 47. METALS. The metallic elements, as already observed, dis- play great diversity as to their general appearance and properties ; and there is, on the other hand, so much similarity between some of these bodies and some of the non-meta'llic elements, that their distinction becomes difficult and inconsiderable. Hence some chemists have hesitated as to the proper mode of classifying cer- tain substances. Silicon and selenium have both been regarded as metals ; and among the bodies which have been always admit- ted into the first class, there is not any perhaps which so much resembles the metals as carbon, in that state of aggregation which constitutes charcoal. 48. The elementary or simple substances, metallic and non- metallic, have so many points of analogy as to render it impossi- ble to form a systematic arrangement of them, adapted for practical purposes, which may not be liable to objection. In this as well as in other cases, nature seems to display a variety of bodies not capable of being separated into orders or sections, strikingly con- trasted with each other, but throughout the whole a gradation ap- pears to take place ; whence may be deduced a chain of simple bodies, variously connected with each other : those that in some respects obviously appear to be members of different classes, approaching nearly together in certain of their properties and modes of action. However, the usual arrangement of the simple bodies into metals, and those which are not metals, may be con- veniently retained, as affording perhaps the most generally appli- cable method of distinguishing them. 49. It will be unnecessary to notice separately each of the metallic elements, as we have done those of a non-metallic nature ; because several of them are, as to their general properties, familiar- ly known, being used either in a state of purity, or combined one with another (forming simple or compound metals), for many common purposes. Thus iron is the usual material for the con- struction of a vast multitude of instruments and utensils for What compound have chemists prepared from fluorine and what is its use ? What are the properties of selenium ? From what substances is it obtained ? Which of the bodies already described have been sometimes regarded as metals ? What appears to be the probability of arriving at a perfect classification of bodies on the basis of distinct peculiarities? What circumstance renders a minute description of the properties ot metals unnecessary ? METALS. 25 Domestic and other purposes; gold, silver, and copper, have been long employed in making the coin current in all civilized countries; lead is used in sheets for covering the roofs of build- ings, in tubes for making waterpipes, and on many other occa- sions; mercury is well known as remaining fluid at a lower temperature than any other metal, or indeed than almost any other liquid : and it is therefore used in the construction of thermome- ters and other philosophical instruments. Zinc is often used in combination with other metals, as with copper in the manufacture of brass, and it is likewise employed alone, instead of lead, for covering houses ; and tin is not only of general utility for coat- ing other metals, as in making tin plate, but also in its combina- tion with copper forming bronze or bell-metal. 50. Perhaps the metals may be most properly characterized with reference to their power as conductors of electricity, which belongs to all of them in a high degree. This, however, is not an exclusive character of the metallic elements, for carbon (charcoal) is also a good conductor of electricity, and in this respect it more nearly corresponds with the metals than silicon or selenium, which are non-conductors. Among the acknow- ledged metals there are many which differ greatly from the more common metallic bodies, in being neither malleable nor ductile : such are antimony, arsenic, cobalt, and manganese. There are others which are distinguished by having a very strong affinity for oxygen ; so that at low temperatures they decompose atmos- pheric air or water, uniting with the oxygen in those bodies to form metallic oxides ; as is found to be the case with the metals which Sir H. Davy discovered to be the bases of potash and soda. Therefore when these metals, named potassium and sodium, are obtained from the decomposition of their respective oxides, potash and soda, the metals thus formed can only be preserved by keep- ing them immersed in ether, which does not act on them. 51. Hence it appears that those bodies formerly termed fixed al- kalies are metallic oxides : and this is also the case with the differ- ent earths ; thus calcium is a metal which combined with oxygen forms calcareous earth or lime, a substance which abounds especially in the animal and mineral kingdoms of nature. The earth called barytes is an oxide of the metal baryum; strontites is an oxide of the metal strontium ; magnesia, in its pure state, commonly called calcined magnesia, is an oxide of the metal magnesium ; and alumine, argillaceous earth or pure clay, is an oxide of the metal aluminum. The more rare kinds of earths, In what manner is zinc extensively employed ? In what different ways is tin applied to other metals ? According to what characteristic property have the metals been classed by Sir H. Davy. For what remarkable property are potassium and sodium distinguished ? What is the true nature of the bodies formerly called fixed alkalies and earths ? In what respect does silicon differ from the other earths ? 26 CHEMISTRY. called yttria, glucina, zircon, and thorina, are also metallic oxides ; and it has been already stated that silica, pure siliceous earth, is an oxide, though its basis, silicon, is not a metallic body. Chemical Affinity. 52. That property of matter which occasions the combination of heterogeneous bodies, is the cause of the principal phenomena of chemistry, and is therefore called Chemical Affinity or Attraction. It is also sometimes termed Elective Attraction, and the Attraction of Composition, to distinguish it from Cohesive Aggregative At- traction. This interesting subject was first systematically studied in France by M. Geoffroy, who formed a table of elective attrac- tions. Bergmann in Sweden, Kirwan in England, Berthollet in France, and Richter in Germany, afterwards paid particular attention to this branch of science ; and the subsequent labours of Dalton, and Sir H. Davy, and of the illustrious Berzelius, Gay Lussac, Thenard and others, have made vast additions to our knowledge, concerning this fundamental branch of chemical science. 53. Chemical Attraction may be defined to be that energy, in consequence of which, different kinds of matter unite to form compounds having properties often dissimilar from those of their component parts, so that the result of chemical combination can only be ascertained, at least in the first instance, by experiment. Thus, if iron filings be dissolved in sulphuric acid, or as it is commonly called, oil of vitriol, a substance will be produced bearing no kind of resemblance to either of its component parts, called by chemists sulphate of iron, and vulgarly copperas, or green vitriol, which is a greenish, semi-transparent, crystallized substance, having nothing of the appearance -of the metal, nor of the sour taste of the acid. Acetic acid, or the acid of vinegar, in the same manner dissolves copper, and constitutes with it the blue efflorescent salt called verdigris. Caustic vege- table alkali is a deliquescent substance, which, as its name im- plies, corrodes flesh ; and sulphuric acid, already mentioned, is a liquid which, when concentrated, acts much in the same man- ner on flesh, but from the union of these bodies, so destructive to animal matter, results the chemical compound, ..sulphate of pot- ash, a salt which, whether solid or dissolved in water, does not act on the skin, and may be swallowed with safety, being used What causes the principal phenomena of chemistry ? By whom has the subject of chemical attraction been extensively culti- vated ? In what manner may its results be ascertained ? What effect on the sensible properties of the ingredients is often pro- duced by chemical composition? What examples illustrate this point ? How does sulphuric acid affect the skin ? What effect does caustic potash produce upon it? What is the operation of sulphate of potash on the living flesh? CHEMICAL AFFINITY. 27 like the somewhat similar compound, sulphate of soda, (Glauber salt,) for medicinal purposes. Sometimes two liquids, or gaseous bodies, by their union, form a solid compound. Thus the gas that rises from spirit of hartshorn, called by chemists ammonia, and muriatic acid gas, if mixed together in an empty jar, become condensed into a white saline solid, called muriate of ammonia, or sal-ammoniac. 54. The manner in which the effect just mentioned maybe conve- niently exhibited, is presented in the above figure, where two retorts, S and L, are connected with a glass globe, by means of two tubulures, into which their necks respectively pass until they nearly meet in the centre. The apparatus being thus prepared, we put into L a mixture of dry slaked lime and sal-ammoniac in fine powder. Into the retort S put a quantity of common salt, sufficient to fill one-third of the bulb. Place the globe on its support, apply a moderate heat to L, and pour sul- phuric acid upon the salt in S. Close both retorts, and the gaseous ammonia from L will combine with the muriatic acid gas from S, forming in the globe a dense white cloud or solid substance, the muriate of ammonia. 55. The phenomena of Chemical Attraction are regulated by the following laws : (1.) This attractive force is exerted in different degrees by different bodies. (2.) It operates only on very minute particles of bodies; and hence chemical action is promoted by previous solution, trituration, or other mechanical methods of division and intermixture. (3.) When bodies combine, an alteration of temperature gener- ally takes place, sometimes with the exhibition of light. (4.) Bodies which have an attraction for each other, are always found to display opposite states of electricity. What is the first law of chemical attraction ? What is the effect of mechanical division on the chemical combination of bodies 1 What sensible phenomena usually accompany chemical changes ? In what relative electrical states are two combining bodies always found? 28 CHEMISTRY. (5.) All bodies are composed of certain atoms or molecules, and chemical combination consists of the union of one or more atoms of one of the uniting bodies, with some determinate number of atoms of the other uniting- body. (6.) Chemical attraction takes place in three different modes : [1.] When one simple body is presented to another, for which it has an affinity, a union takes place, and a compound is formed. [2.] If a simple body, A, be presented to a compound, B C, and if A have a stronger affinity for B than C has, the compound B C will be decomposed, and a new compound, A B, will be formed. [3.] If a compound A B, be presented to another com- pound C D, though neither A nor B alone would decompose C D, yet a mutual decomposition may take place between the two compounds, and occasion the formation of two new compounds, A D and C B. The first and second modes* of attraction are styled instances of simple affinity, or simple elective attraction; and the last mode is styled compound affinity, or compound elec- tive attraction. (7.) All compounds, when they enter into union with other bo- dies without being decomposed, act in the same manner as simple bodies. 56. These laws of Chemical Attraction may be exemplified and illustrated in the following manner : (1.) The first of these laws constitutes the foundation of the whole science of Chemistry. The ensuing examples show the manner in which it operates. If thin plates or filings of copper be mixed with sulphuric acid, (oil of vitroil,) on the application of heat the metal will be dissolved. The acid thus united to the copper will form a salt, called sulphate of copper, (blue vitriol,) which might be ob- tained from the solution by evaporation and crystallization. If to this solution be added iron wire, or thin plates of that metal, the sulphuric acid will leave the copper, and combine with the iron. As the latter dissolves, the former, separating from its union with the acid, deposits itself on the iron plates, so that they become covered with a thin film of copper, but when the iron is all dissolved, the copper having nothing to support it, will fall to the bottom of the containing vessel, in a pulverulent form. The clear liquor, being decanted, will therefore be a solution of sul- phate of iron (green vitriol.) If to this solution filings or frag- ments of zinc be added, the iron will separate by degrees from the liquid and fall down, as the copper previously did, leaving What law appears to regulate combination in regard to the numbers of ultimate particles ? In how many and what different modes may chemical attraction take place ? In what manner do compounds act when their exercise of chemical at- traction is not attended by their own decomposition ? In what manner is the first law of chemical attraction illustrated by copper and sulphuric acid ? What is the resulting compound called ? MINUTENESS OF THE PARTICLES OF MATTER. 29 the zinc in solution, forming' with the acid, sulphate of zinc, (white vitriol.) If to the solution of sulphate of zinc, be added water of ammonia, (pure volatile alkali,) the acid will quit the zinc to unite with the alkali, the metal will be precipitated, and the clear liquor being decanted, will be a solution of sulphate of ammo- nia. Add to this liquor quicklime, which substance will combine with the acid, and separate it from the ammonia, but the new compound of sulphuric acid and lime, thus formed, will not remain in solution, but will be precipitated, or fall down, in the form of a white powder, called sulphate of lime, (gypsum,) while the ammonia, freed from the acid, remains dissolved in the water, from which it may be expelled by heat, in the form of a gas. If the sulphate of lime be separated from the solution by filtering-, and thrown into water containing caustic potash, a new decom- position w r ill take place, the sulphuric acid leaving the lime, and uniting with the potash. The sulphate of potash (vitriolated tartar) thus formed, will remain in solution while the pure lime becomes precipitated in the state of a white powder, and the sulphate of potash may be obtained, in a crystalline form by eva- porating the clear solution, after pouring it from the lime. 57. This succession of decompositions shows that iron possesses a stronger attraction for sulphuric acid than copper, zinc than iron, ammonia than zinc, lime than ammonia, and potash than lime. Numerous experiments of a similar kind might be adduced, which would equally serve to show the relative attractive powers of various substances. It appears from the preceding experiments, that the decomposition of a substance dissolved in a liquid, is sometimes accompanied by the falling down of the newly formed substance, and sometimes by that of the body separated from the original compound. \In this case the body added to produce the decomposition is calle3 the precipitant \ and the substance thrown down the precipitate; the process itself is sometimes termed pre- cipitation. } 58. (2.) The extreme minuteness of the elementary molecules of bodies from the union of which chemical compounds are formed, appears from the entire change of sensible properties resulting from such combinations. For as already stated, the human eye, assisted by the most powerful microscopes which have ever been constructed, ^ften cannot detect in a chemical compound the slightest vestige of the colour of either of its component parts ; By what means may the copper be fe produced in its metallic state ? What will then be the nature of the liquid obtained ? In what manner may the iron in this solution be reproduced ? What may next be employed to separate the zinc? How may ammonia be freed from sulphuric acid ? Will this like the metals undergo precipitation ? How may the separation of lime from the same acid be effected ? What general truths may we deduce from this series of operations? What term is applied to the body which produces precipitation? What name is sriven lo the substance thrown down ? 30 CHEMISTRY. but when substances are mechanically mixed, the respective colours of the ingredients of the composition may sometimes be traced, as when variously-tinted powders are triturated together; or if the mixture is more complete, as when two liquids, for in- stance, ink and water, are shaken together in a phial, though the whole mass will exhibit a uniform appearance, it will be merely a modification of colour, arising from the dilution of the ink by the aqueous fluid./ 59. Some philosophers have ascribed to matter the property of infinite divisibility. But though matter may be conceived to be indefinitely capable of being divided, and though it may even be proved by geometrical demonstration, that a line of a given length may be made to undergo unlimited subdivision, yet there is reason to believe that those bodies with which chemistry is conversant, are formed of indivisible atomsu Matter, then, or rather space, is metaphysically and mathematically, but not physically, capable of being infinitely divided.] 60. It is possible to conceive that a cubic inch may be separated into 10,000 smaller cubes, and each of the latter into as many millions of millions of minuter parts of a similar shape, nor can there be any limit to such subdivision, which must be as exten- sive as the power of enumeration.^ \The mathematical de- monstration of the infinite divisibility of matter is founded on, the impossibility of conceiving any limits to absolute space. ' Let A D and F G, in the marginal figure, be two lines parallel C A T? n ^h eacn other, and perpendicular to the line B C; then from the points H ' H '' H "' H " /j as centres, describe so many arcs of circles, cutting the lines F G and A D ; and since, the line A D may be imagined to be as ex- tensive as space itself, it is impossible to prescribe bounds to the number of points which may be made the centres of circular arcs, and as the number of arcs is bound- less, so will be the number of parts into which they will divide the line F G ; for the arc, how immense soever might be the length of its radius, could not possibly become coincident with the right line B C. 61. These observations are worthy of attention, as they may serve to assist us in forming distinct conceptions concerning the wonderful minuteness of the particles of matter, considered in a physical point of view. Among the numerous instances that What difference in sensible properties may distinguish a chemical com- pound from a mechanical mixture ? What examples may be given of these two effects ? What opinion has been formerly promulgated in regard to the divisi- bility of matter ? What difference exists between the mathematical and the physical di- visibility of space ? On what is the mathematical divisibility of space founded ? Draw and explain the diagram relating to this subject ? BULK OR WEIGHT OF ATOMS. 81 might be produced of the minute division of material bodies, may be mentioned the extreme diffusion of colouring particles through a transparent fluid. A grain of carmine rubbed down with a little water, and then mixed with six quarts more, will give the whole liquid a pale red or flesh colour; and one grain of blue vitriol, (sulphate of copper,) will communicate a fine azure tint to five gallons of water. V Boyle says that a pair of Spanish gloves, which had been scented by a single grain of musk, retained their odour for twenty-nine years. The same philosopher placed a piece of amber, weighing 100 grains, in the scale of a balance, which turned with a small fraction of a grain, and, having counter- poised it, he left it for several days, at the end of which time it had lost no perceptible portion of its weight, though it had been continually giving off particles, which had perfumed the sur- rounding air.*") 62. Malleable and ductile metals are capable of being reduced to a most extraordinary degree of tenuity. vGold, after being sub- mitted to the operations bf the goldbeater, is formed into leaves 3.3 inches square, each weighing rather less than the fifth part of a grain, and being but the 282,000th part of an inch in thickness ; and a particle of this gold leaf, not exceeding the 500,000th of a grain, will be distinctly visible to the naked eye.f Still more comminuted, doubtless, are the particles of gold left in the abra- sion of a gold pin on a touchstone, but yet perfectly perceptible to the sight. Bubbles of soap and water consist of films far more attenuated than leaf gold, for when they begin to reflect colours, their thickness is less than 2,000,000ths of an inch, and that must be much beyond the diameter of the atoms of water ; for the film contains soap incorporated with the water, and we cannot even conjecture what relation the dimensions of the atoms of the fluid may bear to those of the film which it forms, only they must be far inferior. Besides, both soap and water are compounds, so that the constituent atoms of those substances, as of the oxygen and hydrogen of the water, must be yet more reduced, till they almost surpass the power of imagination. 63. v The vegetable kingdom presents us with innumerable in- stances, not only of the extraordinary divisibility of matter, but of its activity, in the almost incredibly rapid developement of cel- lular structure in certain plants. /J'hus the Bovista giganteum (a species of fungus, has been known to acquire the size of a gourd What examples can be adduced of extreme divisibility among colouring materials ? What facts demonstrate the minuteness of odoriferous particles? How may metallic substances be perceived to illustrate the minute di- visibility of matter ? Illustrate the extreme divisibility and the activity of matter in the vegetable kingdom ? * De Mira Subtil. Effluv. Sigaud de la Fond. Elem. de Phys., t. i. pp. 156 et 160. t Leslie's Elem. of Nat. Philos., vol. i. p. 13. 32 CHEMISTRY. in one nighty Now supposing, with Professor Lindley, that the cellules of this plant are not less than ^^th of an inch in diameter, a plant of the ahove size will contain no less than 47,000,000,000 cellules ; so that, supposing it to have grown in. the course of twelve hours, its cellules must have been developed at the rate of nearly 4,000,000,000 per hour, or of more than 66,000,000 in a minute; and when we consider that every one of these cellules must be composed of innumerable molecules, each one of which is again composed of others, we are perfectly over- whelmed with the minuteness and number of the parts employed in this single production of nature.* 64. The animal world affords examples of the incomprehensi- ble divisibility of matter not less wonderful. Mr. Harmer, by counting the number of ova in a given weight of the spawn of different fishes, found that a single flounder contained 1,357,400 ; and a cod-fish no less than 3,686,760 ova ; all of which, it must be remembered, were organized bodies,,capable of developement, so as to form perfect animals. f But the infusory animalcules display, in their structure and functions, the most transcendent attenuation of matter. \The Vibrio itndula, found in duckweed, is computed to be ten thousand million times smaller than a hemp- seed. Vibrio lineola occurs in vegetable infusions, every drop containing myriads cf those oblong points^ The Monas gelatlnosa, discovered in ditch-water, appears in the field of a microscope a mere atom endued with life, millions of them playing like the Bun-beams, in a single drop of liquid.:}: 65. That all bodies are composed of atoms or ultimate indivi- sible particles, may be inferred from the observations which have been made on the height of the atmosphere above the surface of the earth. Dr. Wollaston adduced some ingenious arguments in proof of the limited extent of the aerial medium which surrounds the globe, as resulting from its atomic constitution. And if we admit that such is the nature of the air, it may also be concluded that bodies of greater density consist in the same manner of indi- visible molecules. 66. The instances already mentioned of the extraordinary minuteness of particles of matter relate to bodies which are mani- festly compounds, and the magnitude of such particles must therefore be far superior to that of the ultimate or even the con- stituent molecules of those bodies. With regard to the bulk or At what rote per second are the cells of the Bovista giganteum developed ? What is supposed to be the size of the Vibrio undnLa ? How may we i ' A ! -* : ~ -<- " ' our atmosphere ? How may we infer the atomic constitution of mattet, from the nature of )h r. Prout's Chemistry, Meteorology, and the Function of Digestion Bred with reference to Natural Theology, 1834, pp. 23, 24 ; from * Dr. considered Lindley's introduction to Botany. t Philosoph. Transact., vol. Ivii. 1767, art. 30. t Leslie's Nat. Philos., vol. i. p. 16. $ Sec Scientific class Book, part i. p. 207. COMBUSTION. 3* weight of absolute atoms, or ultimate molecules of matter, we can form no conceptions whatever, and their nature and properties must probably remain objects of conjecture and uncertainty; but the constituent or combining molecules of different substances are more within the reach of experiment and observation, and con- cerning their relative magnitudes or proportional weights, the re- searches of modern philosophers furnish us with some infor- mation. Dr. Thompson has calculated that the weight of a constituent molecule of lead does not exceed 3-To",o"o~olwo\5"o^ t h. of a grain, and that its magnitude is probably much less than T5"8,4F2,-<5-W,o-o <5-,o-o-o tri of a cubic inch - The combining mole- cules of sulphur are vastly inferior to those of lead, each being computed to be not more than T^j/oiTo.o-o-o.o-o^h of a g rain 5 and the molecules of some other bodies are undoubtedly much more diminutive.* 67. The change of temperature that results from chemical com- bination is sometimes very considerable. Thus the burning of char- coal is a combination of charcoal or carbon with the oxygen of the atmosphere, and the consequent production of carbonic acid. Abun- dance of heat is evolved in this process, which has been supposed to be derived from the oxygen gas consumed. Much heat is also given out when nitrous acid or aqua fortis is mixed with oil of amber ; those fluids uniting to form a resinous substance, which, from its peculiar odour, has obtained the name of artificial musk. 68. The elevation or depression of temperature which accompa- nies the formation of chemical compounds has given rise to various hypotheses, among which the most plausible, perhaps, is that which deduces the heat or cold manifested in such cases from the change of state in the elements of the combining bodies, or the relation of their respective capacities for heat with that of the compound. Thus it has been imagined, that when the specific heat of a compound is less than that of the bodies from whose union it is formed, the superabundant heat will be given out and become sensible; and if the specific heat of the compound be greater than that of its component parts, it must absorb heat from sur- rounding bodies, and thus occasion a sensible depression of tem- perature. But this view of the cause of the changes of temperature that take place, is hardly consistent with the conclusions derived What is the state of our knowledge in regard to the ultimate particles of simple bodies? What has modern chemistry developed in regard to the relative weights of the combining atoms of different substances ? How does the size of a combining atom of sulphur compare with one of lead ? What remarkable examples illustrate the third law of chemical attrac- tion? What hypotheses have been raised to account for the developement of heat during chemical combination ? * Thomsons's Principles of Inorganic chemistry, vol. i. p. 7. 34 CHEMISTRY. from the latest researches of philosophers concerning- the specific heat of different bodies, and especially of gases ; and the relation of chemical attraction to heat is a subject which still remains open for future investigation. G9. A few observations may, however, be added concerning two important topics connected with this law of chemical affinity, namely, Combustion, and the Solution of Solids in Liquids. The term combustion has been variously applied by different writers ; some extending it to all cases of violent chemical action, accompanied by the evolution of light and heat ; and others re- stricting it to certain processes in which combustible bodies more or less rapidly combine with oxygen, with the extrication of light and heat, as in the burning of charcoal, noticed above.. .Lavoisier, < who was the first in modern times that clearly ascertained the influence of atmospheric air on chemical operations, and showed that the changes which bodies undergo frequently depend on the absorption of oxygen, ;was led to conclude that all simple sub- stances might be arranged in two classes ; the first comprising oxygen only, which he characterised as a supporter of combustion ; and the second, consisting of combustible bodies, including the metals. Hence he farther inferred that oxygen gas consisted of a ponderable basis, combined with light and heat, which were given out in the form of flame during combustion or the union of combustible bodies, as carbon, sulphur, phosphorus, oil, and alco- hol, with the basis of oxygen gas. ) 70. But this theory, though to a certain extent it may be admitted, is by no means applicable to all cases of combustion in which oxygen gas or atmospheric air is present, and it is necessarily incapable of affording an explanation of those in- stances of the evolution of light and heat consequent on the sud- den union of bodies which contain no oxygen whatever. ^ Thus if equal volumes of chlorine gas and hydrogen gas be introduced into a glass jar, and exposed to the direct rays of the sun, they rapidly combine, with explosion, or the display of abundance of light and heat. Phosphorus burns with a pale yellow flame, when heated in chlorine gas; and when phosphorus is introduced into an exhausted vessel with iodine, a violent action takes place, and much heat is extricated, but without light. If sulphur and filings of copper be heated together, when the mixture has acquired a temperature much below a red heat, it suddenly becomes red-hot, and the compound called sulphuret of copper is formed. ) 71. Many other examples might be adduced of the production What researches of morlern times are found to oppose this theory ? How has the term combustion been used by different writers? By whom was the distinction of bodies into combustibles and supporters of combustion first made ? What led the author to this division ? How has the theory of Lavoisier been modified by more recent disco- veries ? Give some examples of the phenomena of combustion produced with- out the presence of oxygen. SPONTANEOUS COMBUSTION. 35 of heat either alone or accompanied by light, during chemical combinations, in which oxygen is not at all concerned. Unless, therefore, the term Combustion be exclusively appropriated to the process of burning combustibles in atmospheric air, or some other aerial medium in which oxygen is contained, the phenomena with which the process is accompanied cannot possibly be said to be caused by the condensation of oxygen gas ; and in the present state of our knowledge, any attempt to develope their source may be considered as somewhat premature. 72.\^Combustion, as depending on the union of oxygen with a combustible body, sometimes takes place under singular circum- stances, and gives rise to extraordinary appearances. The tem- peratures at which different combustibles combine with oxygen vary extremely.; Potassium, or the metallic body which in com- bination with oxygen forms potash or fixed vegetable alkali, most powerfully attracts oxygen, tarnishing when exposed to the air at a very low temperature, and becoming inflamed when thrown into cold water, or even when placed on a piece of ice, potash being formed in either case. Phosphorus, when quite dry, takes fire in at- mospheric air, at about 100 of Fahrenheit. Sulphur burns in com- mon air at from 180 to 190, but with a faint blue flame, the heat of which is very inconsiderable; but if its temperature be raised to 300, the combustion proceeds more rapidly. -.Carbon, in the state of common charcoal, demands a higher temperature for its combustion than the substances already mentioned ; and in its crystallized form, in the diamond, it requires an intense heat, as the flame of an oxy-hydrogen blowpipe, to set it on fire. When highly comminuted, however, charcoal, and especially some varieties of it, attract oxygen, exhibiting the phenomena of com- bustion at relatively low temperatures ; and hence, in certain cases, what is termed spontaneous inflammation has taken place. 73. Colonel Aubert, an artillery officer, in consequence of re- peated instances of the spontaneous combustion of powdered charcoal which had occurred in France, made some interesting experiments on the subject. He found that charcoal triturated in mortars with bronze pestles, till it is reduced to the finest powder, has the appearance of an oily fluid, and occupies only one-third of the space which it takes up when in the form of rods about six inches in length. In this state of extreme division it absorbs air much more readily than before ; but the absorption proceeds slowly, requiring several days for its completion, and it is accom- panied by the evolution of heat sufficient to raise the thermometer to about 360 of Fahrenheit, and thus inflammation is occasioned. The process commences near the centre of the mass, about five or six inches from its surface, at which spot the temperature is Under what variety of circumstances may combustion take place ? What remarkable instance may be adduced in which combustion com- mences at low temperatures ? Under what different circumstances may carbon be ignited ? What investigation was made by Aubert on the combustion of charcoal ? 36 CHEMISTRY. always higher than at any other. Black charcoal, strongly dis- tilled, is more readily inflammable than lighter varieties. Masses of this kind of charcoal, less than 66 pounds avoirdupois, do not inflame spontaneously ; and the other kinds inflame only when in larger masses. The free admission of air to the surface is indis- pensably requisite to produce spontaneous combustion. When sulphur and nitre are added to the pulverized charcoal, the in- flammation does not take place as usual ; but there is still some absorption of air, and augmentation of temperature ; therefore it would be dangerous to leave large quantities of such mixtures long exposed to the air.* 74. The spontaneous combustion of substances containing car- bon, from the absorption of air and moisture is a phenomenon of so frequent occurrence that few persons can be ignorant of it, though those who are unacquainted with chemistry must be at a loss to account for it. Ricks of hay arid stacks of corn thus oc- casionally take fire, and are consumed ; and repeated narratives have been published of the destruction of packages of coffee, bales of cotton and other articles, in consequence of spontaneous inflammation. Much appears to depend in these cases on the pre- sence of water; for hay-ricks take fire only when the hay is put together before it is properly dried, or in consequence of its not being well secured from the rain. An instance of the spontaneous combustion of a quantity of oatmeal, which had been left in the house of a gentleman at Glasgow, during the absence of his fa- mily from home from May till the end of August, in 1820, is mentioned in Dr. Thomson's "Annals of Philosophy;" and the accident is justly attributed to the avidity with which oatmeal attracts moisture, a property that induced Professor Leslie to employ it instead of sulphuric acid, in his ingenious process for the production of ice under the exhausted receiver of an airpump.f 75. Spontaneous combustion sometimes takes place very sud- denly. Prof. Bache, of Philadelphia, discovered that carbon in the state of lamp-black, or the soot of animal oil, causes the in- flammation of a stick of phosphorus powdered with it, at the tem- perature of 60 of Fahrenheit, either in the open air, or in a close receiver of a moderate size.}: 76. Professor Doberiener, of Jena, discovered a curious phe- nomenon of an analogous nature relative*4o spontaneous combus- tion in 1823. He found that platina, in the state of very fine wire, thin leaves, powder, or in the spongy form, at the common temperature of the air, if plunged into a mixture of hydrogen gas What effect on the combustibility of powdered charcoal arises from mixing with it sulphur and nitre ? How may the spontaneous combustion of hay, cotton, coffee, oatmeal, &c. be explained ? In what manner may phosphorus and charcoal be inflamed ? * See Ann. de Chim. ; and Edinb. Journ. of Science, N. S. No. 8. t See Journ. of "Science, ed. at JR.. I., vol. x. p. 454 ; and Ann. of Philos., vol. xvi. p. 390. J Silliman's Journ. of Science INFLUENCE OF HEAT ON SOLUTION. 37 and atmospheric air, would almost instantly take fire. The pla- tina becomes heated, presently red hot, then it attains a white heat, and immediately the hydrogen inflames, and the combustion continues as loner as any portion of the combustible elements re- mains. Brewster says : *' In this case the minutely-divided pla- tina acted upon the hydrogen gas in the same manner as the minutely-divided charcoal acted upon common air. Heat and combustion were produced by the absorption of both gases, though in the one case the effect was instantaneous, and in the other was the result of a prolonged absorption."* 77. This property of spongy platina has been happily applied to a purpose of.much practical utility, by M. Gay Lussac, in the contrivance of a lamp for the production of instantaneous light. Improvements or modifications of this instrument have been made by Mr. Garden and others ; but the principle on which the appa- ratus is constructed is the same in all, and they consist of ar- rangements for the regulated production of hydrogen gas, from the solution of zinc or iron in diluted sulphuric acid, and by open- ing a stop-cock throwing a current of the gas on a mass of spongy platina, which becoming red-hot, the hydrogen inflames, and af- fords the means for lighting a taper. 78. One form of Gay Lussac's ap- paratus is seen in the annexed figure. A glass vase containing a solution of sulphuric acid in the proportion of one part acid to 15 or 20 of water, has a cover of brass resting on its upper rim, to which is cemented a conical glass jar of smaller dimensions, open below and per- forated above, for the escape of gas when required. From a brass rod on the interior of this second jar, is sus- pended a cylinder of zinc, the bottom of which is nearly as low as that of the conical jar. A stop cock above the brass plate opens a communication with the interior glass vessel, and allows the hydrogen gas to escape through a small pipe or nozzle, and be projected on a bit of spongy platina, contained in a thimble-shaped receptacle near the periphery of the lid, when it soon becomes red hot, and ignites the jet of hydrogen gas. 79. Numerous experiments were made by MM. Dulong and Thenard, with a view to elucidate the cause" of the inflammation What is the nature of Dobereiner's experiment on the ignition of platina ? What explanation of the result has been attempted ? How has Guy Lussac applied to practical purposes the experiment with spongy platina? Describe his apparatus ? 1 * Sir D. Brewster's Natural Magic, p. 318. 38 CHEMISTRY. produced by the contact of finely-divided platina with hydrogen gas. From their researches it appeared 1. That palladium, rhodium, and iridium, have the same effect on the gas with pla- tina; 2. That osmium in like manner produces inflammation, but requires a temperature of 45 centigrade, and gold inflames at 120 ; 3. That charcoal, glass, pumicestone, and porcelain, have similar effects, but at temperatures near 250 ; 4. That all these bodies lose the property in question by long exposure to the air, but they recover it on being calcined.* 80. Among the various causes of spontaneous combustion that might be mentioned, there is none more interesting or curious than that of the human body, many instances of which are upon record. But the subject will again be noticed, in treating of the effect of electricity on chemical attraction, and therefore need not be intro- duced here. 81. Elevation of temperature generally promotes the chemical action of bodies. Its influence in many cases appears to depend on the diminution of cohesion, or the separation of the particles of matter by heat, as when expansion or liquefaction takes place. 1 But its effects are sometimes more complicated and obscure; and the phenomena indicate an obvious correspondence between heat and electricity or galvanism. A remarkable instance of the in- fluence of heat, in conjunction with light on the chemical union of bodies, may be pointed out in the production of muriatic acid from the mixture of chlorine and hydrogen gases, noticed above. When the proper quantities of these gases required to form the compound are mingled in a glass jar, so long as light and heat are excluded no combination takes place, but if the mixture be exposed to the direct rays of the sun, detonation ensues, and muriatic acid gas is formed ; and the same effect is produced by introducing into the jar a lighted taper, or passing through its contents an electric spark. 82. It must be observed, that, though elevation of temperature to a certain extent may facilitate the chemical union of bodies, the effect will depend, in any given case, on the adaptation of the de- gree of heat to the particular process. Thus mercury exposed to the contact of atmospheric air at the temperature of nearly 680 Fahrenheit, in a proper vessel, combines with oxygen to form the red oxide of mercury, which substance, when exposed to a red heat, 1275, becomes decomposed, returning to the state of metal- lic mercury and oxygen gas. 83. Temperature has generally a great influence on the solvent "power of water, and also on that of other liquids. Hot water is What four resulls did Dulong and Thenard obtain from their experi- ments on this subject ? What effect has elevation of temperature on chemical attraction? On what does this effect appear to depend ? What remarkable example of this can be exhibited ? What diversity of effects may be found to arise from different degrees of elevation in temperature? * Pouillet Elera. de Phys., vol. i. pp. 425, 426. INFLUENCE OF HEAT ON SOLUTION. 39 capable of holding in solution larger quantities of most substances than cold water: thus, saltpetre, or nitrate of potash, arid chlorate of potash, are much more readily soluble in water at a high than at a low temperature ; and with regard to many other saline bodies the dissolving power of the liquid is increased by augmentation of temperature. But this is by no means always the case. Water cooled to near the freezing point, will take up almost double the quantity of caustic lime that can be held in solution by boiling water. Glauber salt, or sulphate of soda, is most readily soluble in water at about 92 Fahrenheit,] (33 cent.,) the solvent power of water with respect to that salt increasing with the augmentation of heat up to that point, after which it diminishes to 215, at which temperature nearly the same relative quantity of the salt will be taken up as at 87. Seleniate of soda likewise is more soluble at 92 (33 cent.) than at a higher or lower temperature. Pans C 10 20 30 40 50 60 70 80 90 100 110 F 32 50 68 86 104 122 140 158 176 194 212 230 N. P. nitrate of potash. S. M. sulphate of magnesia (anhydrous.) S. S. sulphate of soda (anhydrous.) Chi. B. chloride of baryum (anhydrous.) Ch. Prn. chloride of potassium. Chi. S. chloride of sodium. Cht. P. chlorate of potash. S. B. sulphate of barytes. S. P. sulphate of potash. What effect has elevation of temperature on the solvent power of liquids ? What remarkable exception to this law has been observed ? At what temperature will water dissolve the greatest quantity of the sulphate or the seleniate of soda ? At what temperature Fah. would a given quantity of water dissolve as much chlorate of potash as it would of the sulphate of barytes ? [See table.] What number of parts of either of those salts would 100 parts by weight of water dissolve at that temperature ? Of what salt will water dissolve the same quantity at all temperatures? At what temperatures is the solvent power of water the same for nitrate of potash as for sulphate of magnesia ? At what two points will it take up erjnal quantities of sulphate of soda and of chloride of potassium ? 40 CHEMISTRY. 84. The relation between temperature and solubility will be most distinctly perceived from the inspection of the preceding table. The vertical line of figures indicates the respective por- tions of several salts, taken up by 100 parts of water, and the horizontal line of figures denotes the temperatures of which the solutions take place. The line which is marked Chi. S., shows the solubility of chloride of sodium, (common salt,) and it cuts the perpendicular lines all at the same height No. 37, which indi- cates that one hundred parts of water will at all temperatures dis- solve 37 parts of common salt. The line marked Chi. B., anhydrous chloride of baryum, cuts the perpendicular line marked at No. 31, that which is marked 55 at No. 45, and that marked 110 at No. 61 . hence it must be understood that 100 parts of water will take up 31 parts of anhydrous chloride of barynm at zero, 45 parts at 55, and 61 parts at 110. The line marked S. S., sulphate of soda, rises to 33 and then descends, denoting the sulphate to be most soluble at that temperature, as above stated. The manner in which the various influence of temperature on other salt is exhibited in this table will be sufficiently obvious from the preceding examples.* 85. (4.) The influence of electricity on chemical processes, attract- ed the attention of philosophers before the middle of the last century, when it was' ascertained that ether might be fired by the electric spark; and the deflagration of spirit of wine, fulminating gold, and some other inflammable bodies, was soon after effected by the same means. More recent researches evinced the possibility of producing the combustion of iron wire by exposing it to the shock of an electric battery. The metal is thus oxidated in the same manner as by the violent friction caused by striking fire with a flint and steel. Other metals, as well as iron, may be made to undergo combustion by exposing them to the charge of a battery of elec- 1 trie jars. A fine gold wire may thus be burnt, yielding a bluish- white flame, and the product will be a protoxide of gold, in the state of an impalpable purple powder. Silver wire may in the same manner be made to burn with a green flame ; and corres- ponding phenomena take place with the other metals. 86. The effect of the electricity of excited jars on the combi- nation of gases, was the subject of experiments by Mr. Waltire, Dr. Priestly, and Mr. Cavendish ; and the latter, about 1776, thus How early was the connection between electrical and chemical actions discovered ? What observations led to this discovery ? What effect has a discharge of electricity on fine iron wire ? When and by whom was the action of electricity on gases investigated ? * This Table is taken from Mitscherlich's Introduction to Chemistry (Germ.), Berlin, 1832 8vo. vol. i. p. 287. The temperatures are given ac- cording to the scale of both the centigrade and Fahrenheit's thermometer. In this arid all similar cases the student will change degrees centigrade into those of Fah. by taking 9-5ths of the number of the former and ad- ding to it 32. Ed. ELECTRICITY. 41 produced water, by firing a mixture of hydrogen gas and atmos- pheric air ; and lie also obtained nitric acid, by employing elec- tricity to determine the combination of oxygen and nitrogen. In 1781, Lavoisier and Laplace made important experiments on the development of electricity in the evaporation of liquids, and the solution of solids, as when metals are dissolved in diluted acids; and from the latter researches of Becquerel, at Paris, it may be concluded that electricity is evolved in all cases of chemical so- lution.* 87. The relation between electrical and chemical attraction has been confirmed by the discovery of Galvanic or Voltaic electricity, the effects of which manifestly depend on the same peculiar energy that gives rise to the phenomena of the Leyden phial. It has been ascertained that chemical decompositions and combinations can be accomplished more easily and readily by means of the Voltaic pile or battery, than by the aid of an electrical machine and the apparatus belonging to it. 88. Some notice has been taken of the chemical power of the Voltaic battery in the preceding volume of this work, to which the reader is referred for an account of the construction of Galvanic or Voltaic troughs, for the reception of zinc and copper plates with an interposed fluid, which may be used for the production of various chemical phenomena.* With such a Voltaic ba'ttery, water and other chemical compounds in a fluid state may be decomposed, merely by dipping the extremities of two wires communicating with the opposite poles of the battery beneath the surface of the mass of fluid, and thus causing the latter to form part of a Voltaic circle. The decomposition of a saline substance, as sulphate of soda, may be thus effected, by using a glass tube bent so that the angular part may fit into a common wine-glass, which will serve to support it. Then into the open ends of the tube insert two wires or strips of platina'foil, which may reaoh nearly to the angle, but must not come in contact ; fill the tube with a solution of the sulphate, and connect one of the wires with the zinc or negative pole, and the other with the cop- per or positive pole, of a Voltaic battery, and the salt will be decomposed, the alkali or soda collecting in the leg of the inverted siphon or tube in connexion with the negative pole, and the sulphuric acid in the part of the tube connected with the positive pole. 89. In all cases of decomposition by means of electricity, whether derived from the friction of glass, as by the common What general truth in regard to this subject appears to result from the experiments of Lavoisier, Laplace and Becquerel? What aid has the discovery of Galvani afforded in the study of electro- chemistry ? Describe the manner in which a saline substance may be decomposed by Galvanic electricity ? * See Scientific Class Book, part i. page 440 to 446 inclusive. D 2. 42 CHEMISTRY. machine, or from the contact of perfect and imperfect conductors, as in the Voltaic battery, it will be found that one of the constitu- ent elements of the body undergoing 1 decomposition will be evolved at the negative pole, and the other at the positive. Hence it must be concluded, that the bodies thus separating must, with respect to each other, be actuated by opposite kinds of electricity ; and the observation of this phenomenon has led to an arrangement of bodies in two classes, namely, electro-negative and electro- positive substances;, all those kinds of matter which are-attract- ed by the positive pole of a Galvanic battery being included in the former class, and all those attracted by the negative pole in the latter class. 91. Thus in the decomposition of water in the apparatus repre- sented in the accompanying figure, the wire Z connected with the zinc plate or pole of a Voltaic apparatus, &c., with the negative there will be from the end of the platina wire P, a developement ol oxygen, and from N an escape of double the bulk of hydrogen, both of which rising into their respective branches of the tube will be collected at O and at H. But though the distinction between the electro-negative and the electro-positive bodies is sufficiently ob- vious in the decomposition of compounds of two bodies of the opposite classes, yet it requires modification when applied to com- pounds resulting from the union of two electro-negative or two electro-positive bodies respectively. 92. Oxygen when separated from its combination with other simple bodies by electricity, is always evolved at the positive pole; and it may therefore be concluded that it is the most electro- negative of all known substances. 1 It forms compounds with chlorine and the other electro-negative elements, constituting the chloric, iodic, and bromic acids ; and when these are decomposed by the Voltaic battery, the oxygen is evolved at the positive pole, and the chlorine, iodine, or bromine, at the negative pole. In the same manner the electro-positive elements enter into union with What remarkable circumstance always attends decomposition by means of electricity ? What inference are we allowed to draw from this fact? What constitute the class of electro-negative bodies ? What the electro-positive ? To which pole does the electro-negative matter pass ? Under what circumstances will it disappear? Describe the apparatus for decomposing water? Which is the most electro-negative of known bodies? EFFECTS OF ELECTRICITY. 43 each other, forming- compounds which, when electrically decom- posed, manifestly indicate gradations of electric energy among them. Sulphur, which, with respect to oxygen, chlorine, iodine, and bromine, and probably some other simple bodies, is electro- positive, becomes electro-negative when combined with hydrogen ; for when a compound of sulphur and hydrogen is decomposed by Voltaic electricity, the sulphur appears at the positive pole, and the hydrogen at the negative. The sulphurets of carbon, phos- phorus,^and many, if not all the metals, exhibit similar phenomena. 93. Hence it appears, that sulphur is only relatively electro- positive, as in its combinations with oxygen, while it becomes electro-negative by being united to hydrogen, carbon, phosphorus, and the metals.* Experiments are wanting to enable us to as- certain how far the electricity of all bodies is merely relative, or whether the disposition of bodies to be attracted by the positive pole of a Voltaic pile or battery, which seems to exist in the strongest degree in oxygen, descends* by a regular gradation throughout the catalogue jj \jstances. We may remark, however, that while th^6ejlffi**r been designated electro- negative bodies display the highest electro-chemical energy, or tendency to be attracted frbm their compounds by the positively electrified wire, hydrogen and some of the metals seem to have in an extreme degree the contrary disposition to be attracted by the negative wire. 94. The influence of electric attraction on the chemical affini- ties of bodies is especially observable in the combination of metals with oxygen, and in the decomposition of metallic salts. Pure pot- ash or vegetable alkali is a compound of oxygen with the metal called potassium ; and the affinity between those bodies is so strong that chemists were long baffled in their attempts to effect their decomposition. > At length Sir H. Davy succeeded, by ex- posing moistened potash to the action of a Voltaic battery ; thus augmenting the respective electro-chemical energies of the oxy- gen and the metal, they were severally attracted by the wires connected with the opposite poles, and the former was evolved at the positive, while the latter (the metallic potassium) made its appearance at the negative pole. 95. Some other curious and interesting phenomena, relating to What is the relative electric condition of sulphur compared with that of hydrogen, carbon, phosphurus, and metals? What substances appear in the highest degree electro-positive ? In what cases is electric attraction most remarkahle in modifying che- mical action ? What striking example of this is afforded in the history of chemistry ? With which electrical pole must a melal capable of oxidation by an acid be connected in order to prevent that effect ? * For some interesting and curious observations on the electro-chemical proper! ies of sulphur, see " Report on the Recent Progress and Present State of Chemical Science. By James F. W. Johnston, A. M." Reports of the British Association for the Advancement of Science, 1832, pp. 440-442. 44 CHEMISTRY. the affinities between metals and acids may here be noticed, as tending to illustrate the influence of electricity on the chemical union of bodies. Metals may be immersed in liquid acids, which under common circumstances reduce them to the state of oxides, but the action of such acids may be suspended by rendering the metal electro-negative, or placing it in communication with the negative pole of a Voltaic battery^ If two polished plates of iron or copper be plunged in diluted sulphuric acid, one of the plates of either metal having been connected with the positive wire of a Voltaic battery, and the other plate of the metal con- nected with the negative wire, it will presently be perceived that the plate rendered positive will become tarnished and corroded by the action of the acid, while it will take no effect on the negative plate, which will remain as bright as before immersion. Silver unprotected is readily acted on by diluted nitric acid, which dis- solves the metal placed in contact with it, just as sulphuric acid dissolves iron ; but if the silver be rendered electro-negativej it is enabled to resist the pow of the acid, even when long immersed in it. 96. As electricity is evolved by the contact of different metals with water and other fluids, hence it sometimes happens that two metals connected together and plunged in an acid or saline liquid, may form a kind of miniature Voltaic apparatus, and the common ef- fect of the menstruum is augmented with respect to one of the metals, and controlled or suspended with respect to the other. Let a small piece of sheet copper be dropped into a tumbler-glass, containing two drams of nitric acid diluted with ten drams of water, and in a short time enough of the metal will be dissolved to give a bluish tint to the liquid : the addition of a few drops of liquor of ammonia will increase considerably the depth of the colour, and render it more perceptible. Now, if a plate of copper united to one of zinc be immersed in an acid mixture of the same kind, it will not act at all on the copper, but will more rapidly dissolve the zinc than if that metal were plunged in it alone. That the copper in this case is protected by the zinc from the action of the acid menstruum, will appear on dropping into it liquor of ammonia, as before ; for it will now produce no effect, since though that alkali communicates a blue or purple colour to solu- tions of copper, no such change takes place on adding it to those of zinc. Iron may thus be shielded from the dissolving power of acids, as will appear by immersing a polished plate of that metal, with one of zinc attached to it, in any weak acid, as the muriatic, (spirit of salt,) largely diluted with water ; for while the zinc will undergo solution, the plate of iron will remain bright and untarnished, though if plunged in the diluted acid alone, it would be acted upon immediately. How may silver be preserved from corrosion when immersed in nitric acid? How may the preservation of copper from corrosion in salt water be ef- fected ? How is it proved that in this case no copper is dissolved ? METALLIC CRYSTALLIZATION. 45 97. On the observation of the electro-chemical effects of the contact of metals was founded a method, proposed by Sir H. Davy, for preserving the copper sheathing of ships from the cor- roding 1 action of sea-water. It has long been the custom among ship-builders to cover the outer surface of the hulls of large vessels with sheets of copper, the durability and consequent ad- vantages of which were found to be greatly diminished by the action of the saline matters contained in the sea-water on the metal, producing oxidation, corrosion, and decay. 98. The plan proposed for the prevention of these injurious effects of the exposure of the copper sheathing of ships to the ac- tion of sea-water during long voyages, consisted in fixing to the surface of the copper plates of zinc or iron, called protectors, the effect of which was to render the copper electro-negative, and thus prevent it from attracting oxygen from the water, or substances held in solution in it ; the protectors themselves becoming oxi- dated and greatly dissolved, while the copper was preserved. Experiments conducted on a small scale, and for a very limited period, showed that the effect intended might certainly be pro- duced, but it was found that when a copper-bottomed vessel was armed with Davy's protectors, though the copper in the course of a long voyage was prevented by its electro-negative energy from becoming oxidized, yet from the same cause it powerfully attracted from the sea-water earthy matter, such as lime, magne- sia, and other electro-positive bodies dissolved in it, and thus ac- quired a rough coating, to which marine plants and animals be- came attached so abundantly as to prove a serious inconvenience. The failure of this plan, under such circumstances, only serves more strikingly to illustrate the principle under consideration. 99. In the whole range of experimental chemistry there are few phenomena more curious or beautiful than those exhibited by metal- lic arborizations, or the depositions of crystallized metals, from the decomposition of metallic salts. An attention to the manner in which such experiments are conducted will enable us to trace a strong analogy between those processes, and some of the instances of electro-chemical decomposition previously adduced. 100. The production of the Tree of Diana, (Arbor Dianas,) a process said to have been invented by Lemery, a French chemist, in the beginning of the last century, must have excited the admi- ration of many persons quite unacquainted with chemistry. To form this crystallization, let six drams of a saturated solution of pure silver in nitric acid, and four drams of a similar solution of mercury in the same acid, be diluted with five ounces of distilled water, and poured into a small decanter or glass phial ; then com- pose an amalgam, by mixing one part of finely-divided silver By whom was the application of these facts to practical purposes sug- gested ? Explain the purpose to which they were applied, f n what manner is a ship's copper protected from corrosion ? What inconvenience arose from the use of Davy's protectors? Explain the experiment called Arbor Dianas ? 46 CHEMISTRY. with seven parts of mercury, and place a small lump of it at the bottom of the bottle, which must be kept quite still. In a short time the surface of the amalgam will be covered with minute filaments of silver, and after standing about forty-eight hours, the solution will deposit all its silver, in the form of brilliant abores- cent crystals, springing like a glittering shrub from the bottom of the vessel.* 101. An experiment of a very similar nature, which requires less skill and attention in its management than the preceding, is the reduction of lead in the crystalline state from its combination with acetic acid, by means of zinc. This may be effected simply by suspending a lump of zinc in a solution of acetate of lead, commonly called sugar of lead, in the proportion of two drams of the salt to -six ounces of water, contained in a glass phial or flask. In this case the revived metal is deposited more slowly, forming shining foliated crystals, first covering the surface of the zinc and then extending from it towards the bottom of the phial. Here the electro-positive zinc attracts oxygen from the relatively electro-negative lead, and forms acetate of zinc, while the lead is set free. 102. The decomposition of metallic salts may be effected by means of electro-positive bodies not of a metallic nature, giving rise to appearances much resembling those already described. If a lump of charcoal be suspended in a solution of sulphate of copper, the metal will be gradually revived, forming small crystals on the surface of the charcoal. And a stick of phosphorus immersed in a solution of nitrate of silver will become covered with a crystal- line incrustation of the reduced metal. 103. The following method of forming metallic arborizations on the surface of glass, so as to produce a pleasing effect, was published a few years ago in a French journal. Place a few filings of copper arid of iron on a glass plate, at a certain distance one from the other. Then drop a little nitrate of silver (in- solu- tion) on~emble ? * From the Greek, 'Iw, which screws on the lamp c. The whole is protected and rendered convenient for carrying by the frame and ring d. The small coil of platina wire, /?, hung within the wire gauze cylinder being heated by the flame of the lamp, will continue to glow even when the flame quits the wick of the lamp, on being introduced into an atmosphere of fire damp, thus affording a feeble light to the miner who would otherwise in such cases be left in total darkness. When made of plain wire gauze the wire should be not less than one- sixtieth of an inch in thickness, and the number to the inch, each way about 28 or 30. 283. Carburet of hydrogen may be procured by heating gently, over a lamp, in a retort, four parts of sulphuric acid, and one of alcohol. In this operation the mixture becomes black, and an abundant disengagement of gas takes place, which may be collected over water, and purified by agitating it with lime-water, or solution of potash. This gas is colourless, and when pure has but little smell. It is inflammable, burning with a dense white flame, which gives much light. Water absorbs about of its bulk of this gas, and it is also absorbed by sulphuric acid, without under- going decomposition. If, however, these bodies be placed in con- tact for several days, one volume of sulphuric acid will absorb between eighty and ninety of the gas, forming a peculiar compound. 284. When sulphur is heated in a given quantity of this gas, carbon is separated, and twice its bulk of sulphuretted hydrogen formed. As hydrogen undergoes no change of volume in com- bining with sulphur, it appears that carburetted hydrogen must contain two volumes of hydrogen condensed into the space of one ; hence this gas requires for its complete combustion three volumes of oxygen, and the product will be water and two volumes of carbonic acid. This gas may also be decomposed by passing it, and repassing it through a red-hot tube of iron or earthen-ware, Explain the construction of Davy's, safety lamp to prevent that effect? How is carburet of hydrogen obtained ? What are the sensible and chemical properties of this gas ? How is it decomposed by sulphur ? How by heat ? * See Scientific Class Book, pt. i. Pyronomics, No. 144 and 145 p. 326. COMPOUNDS OF CARBON AND HYDROGEN. Ill when the carbon it contains is deposited, and its hydrogen be- comes expanded to double the original bulk. 285. This gas when first discovered, in 1796, was termed ole- fiant gas, from its property of forming a substance like oil when added to chlorine. If equal quantities of carburet of hydrogen and chlorine be mixed together, a diminution of bulk takes place, and a substance is produced, having the appearance of oil, but resembling ether in its general properties. It is a liquid which boils at 152 Fahrenheit, and its specific gravity at 45 is 1.22. It consists of equal volumes of chlorine and carburet of hydrogen, and it has been termed hydrockloride of carbon. Olefiant gas also combines with iodine and bromine, to form definite compounds. 286. In addition to the gaseous carburet and subcarburet of hydrogen, Dr. Dal ton and some other writers, mention a third compound of carbon and hydrogen, called super-olefiant gas, as it requires, for its complete combustion, a larger proportion of oxygen than the olefiant gas. But it seems uncertain whether this elastic fluid is a definite chemical compound, or merely a mixture of the preceding inflammable gases. There are, however, several other combinations of carbon and hydrogen, which are, under common temperatures and pressures, liquids or solids. Among the former may be mentioned two liquids obtained by Mr. Faraday, from the fluid matter which occurs in the distillation of whale-oil, for the production of oil-gas, one of which is the lightest of all known bodies, except gases, its specific gravity being 0.602; naphtha, a volatile, inflammable liquid, obtained during the distillation of coal-tar, and also occuring in some parts of the world, in springs, more or less mixed with water ; oil of wine, formed during the preparation of sulphuric ether ; rectified oil of turpentine, which appears to be very similar in its constitution to naphtha ; oil of lemon, and probably other essential oils. 287. The solid compounds of carbon and hydrogen include naphthaline, a crystalline body, which occurs in the distillation of coal-tar ; paraffin, another crystallizable substance, found among the products of the destructive distillation of wood ; a kind of scaly crystals held in solution by oil of roses, from which they may be, separated by exposure to a low temperature, and the crystals may be freed from the adhering oil by pressure between leaves of blotting-paper, kept very cool ; and caoutchouc, or the substance called Indian rubber. 288. There is a circumstance highly deserving of attention with regard to the compounds of carbon and hydrogen which may here be noticed. So far as we are acquainted with the atomic What name was at first given to it ? How is the hydro-chloride of carbon obtained ? In what state does it exist? What are its composition and character? What other liquid compounds of hydrogen and carbon are enumerated ? What solid compounds of the same ingredients are known to chemists? 112 CHEMISTRY. constitution of these bodies, they appear to be susceptible of ar- rangement in classes or sections, each division consisting of a given number of carburets of hydrogen, agreeing with each other in the relative proportions of their constituents, but differing more or less in their properties and modes of action. As examples of the compounds in question, may be specified olefiant gas, paraffin, Faraday's volatile liquid carbo-hydrogen, and oil of wine, in all which carbon and hydrogen exist in equal proportions; and oil of lemon, oil of turpentine, and a liquid called camphogene, or the basis of camphor, in which the quantity of carbon is to that of hy- drogen as 5 to 4. Other instances of a corresponding nature will be noticed in treating of phosphorus. 289. Carbon unites with nitrogen to form a remarkable com- pound called cyanogen, or the basis of prussic or hydrocyanic acid, which, by its combination with oxide of iron produces Prus- sian blue. It is properly a bicarburet of nitrogen, and in order to obtain it, it is necessary first to form the salt, formerly called prus- siate of mercury, but now cyanuret of mercury. This is composed by boiling red oxide of mercury, with twice its weight of Prussian blue, in a sufficient quantity of water, when those bodies will unite to form a crystallizable compound. The cyanuret of mercury, thus obtained, after having been carefully dried, at a temperature below 212 Fahrenheit, must be heated in a small glass tube, when it becomes black, and liquefies, and is at length decomposed. The mercury becoming condensed in the cold part of the tube, and a gas being at he same time evolved, which must be collected over mercury. This is cyanogen, which at the usual temperature and pressure of the atmosphere, is a permanently elastic fluid, though, as elsewhere stated, it has been condensed to the liquid state by Mr. Faraday. 290. It has a peculiar pungent odour, resembling that of bitter almonds, and it is destitute of colour. It is inflammable, burning in contact with air, with a fine purple flame ; but any burning body, as a lighted match, plunged into it becomes extinguished. It dis- solves in water, and more largely in alcohol. The aqueous solu- tion reddens vegetable blues, and according to Vauquelin, it be- comes spontaneously decomposed, and converted into carbonic and hydrocyanic acids, ammonia, a peculiar acid called the cyanic, and a brown substance containing carbon; the ammonia combines with the acids, and the carbonaceous compound is deposited. These phenomena are owing to the reaction of the elements of cyanogen upon those of water. When cyanogen is mixed with oxygen, it may be exploded by the electric spark. If one volume of this gas and two of oxygen be detonated over mercury, the What remarkable circumstance distinguishes the various compounds of carbon and hydrogen ? What compound results from the union of carbon and nitrogen? What is the true nature of cyanogen ? How is it obtained ? What are its properties ? PRUSSIC ACID BORON. 113 product will consist of two volumes of carbonic acid, and one of nitrogen. 291. Cyanogen, though a compound, enters into combination with elementary bodies, in a manner very similar to the mode of action of oxygen and chlorine. '/ Thus, like oxygen, it combines with several of the metals, constituting compounds, which might be termed cyanides, though they are generally called cyanurets, and as chlorine forms with hydrogen muriatic acid, so cyanogen, combined with hydrogen forms hydrocyanic or prussic acid. 292. The chemical properties of this acid may here be described. It may be obtained by heating, in a tubulated glass retort, three parts of cyanuret of mercury, with two parts by weight of concen- trated muriatic acid. A vapour rises, consisting of water and the muriatic and prussic acids, the former of which may be separated by passing the vapour through a narrow tube, containing frag- ments of marble. It must then be passed over dry chloride of calcium, and condensed in a vessel surrounded by ice. 293. The prussic acid thus obtained, is a limpid fluid with a strong smell, like th^at of laurel water or bitter almonds, and an acrid taste. It is extremely deleterious, proving destructive to animal life, in a small quantity, when either swallowed or inhaled, and therefore the utmost care should be taken in preparing it to avoid breathing the vapour, which, when much diluted with atmo- spheric air, will cause giddiness and headache. This acid volatilizes so rapidly, as to freeze in consequence of the cold pro- duced by its evaporation. Its specific gravity compared with hy- drogen is 13.5, 100 cubic inches weighing 28.593 grains. It con- sists of one volume of cyanogen, and one of hydrogen. This acid slightly reddens litmus paper, and it combines with alkalies and other bases to form salts ; but its affinities are so feeble, that these compounds are decomposed even by carbonic acid. It dissolves in any proportion in water and alcohol ; and it is occasionally used as a powerful medicine, and therefore in small doses, chiefly as a sedative, in cases of phthisis pulmonalis. Boron. 294. This substance is usally obtained by heating together, in a copper or iron tube, one part of boracic acid, formerly called the fiedative salt of Homberg, previously melted and powdered, and two parts of potassium ; when the temperature being raised till the tube becomes red, the metal attracts the oxygen from the acid, and the boron may thus be procured, in the form of a brown pow- der, having neither taste nor smell, and insoluble in water, alcohol, What results from the detonation of cyanogen and oxygen ? What analogy exists between cyanogen and oxygen or chlorine ? Give examples of this analogy. What name is given to its compound with hydrogen ? What are the properties of hydrocyanic acid ? What is its composition ? How is boron procured ? 114 CHEMISTRY. ether, or oil, even when heated. It is permanent in the air at com- mon temperatures, and is infusible. It is a non-conductor of electricity ; and its specific gravity is more than twice that of water. It does not decompose water when heated to 176 of Fahrenheit. ' At low temperatures, boron remains unchanged in atmospheric air or oxygen ; but at a temperature of 600 of Fahren- heit it burns with brilliancy, becoming united with oxygen, and forming boradc acid. 295. By means of an apparatus represented by the annexed en graving, Dr. Hare has succeeded in evolving boron by the reaction of potassium with vitrified boracic acid, in vacuo, without en- countering the evil of any explosive action, to which the process, as heretofore conducted in pleno, has been found liable. " A circular brass plate, is prepared, like the plate of an air pump, so as to produce, with any suitable receivers properly ground, an air-tight juncture. It is supported on the upper end of a hollow brass cylinder, B, with the bore of which it has a corresponding What are its properties ? At what temperature is its combustion effected? What is the result of that process ? PROCESS FOR THE EVOLUTION OF BORON. 115 aperture. The brass cylinder is about three inches in diameter, and six inches in height, being inserted at its lower end into a block of wood as a basis. This cylinder receives below, a screw, which supports a copper tube, C, of about two inches in diameter, so as to have its axis concentric with that of the cylinder, and to extend about four inches above the plate. The copper tube, thus supported, is closed at the upper termination by a cup of copper, of a shape nearly hemispherical, and soldered at the upper edge, to the edge of the tube ; so that the whole of the cavity of the cup, is within that of the tube. Hence the bottom of the cup is accessible to any body, not larger than the bore of the tube, with- out any communication arising between the cavity of the tube, and that of any receiver placed upon the plate, over the cup and tube, as in the figure. " Into the side of the cylinder supporting the plate, a valve cock is screwed, by means of which, and a flexible leaden tube, a com- munication with an air pump is opened, or discontinued, at pleasure. 44 The cup being first covered with a portion of the vitrified boracic acid, as anhydrous as possible, and finely pulverized, the potas- sium is introduced, and afterwards covered with a further portion of the same acid, two parts of the potassium being used for one of the acid. A large glass receiver is now to be placed on the plate, secured by rods A, A, concentric with the tube and cup ; from the heat of which the glass is to be protected by a bright cylinder of sheet brass, S, placed around it so as to be concentrical with the receiver and tube. 296. " The apparatus being so prepared, and the receiver exhausted of air by means of the air pump, an incandescent iron is introduced through the bore of the tube, so as to touch the bottom of the cop- per cup. In a short time a reaction commences, which aiding the influence of the hot iron, renders the cup and its contents red-hot. A deep red flame appears throughout the mass, after which the reaction lessons, and the heat declines. 44 When the cup has become cold, the air is admitted into the re- ceiver, and the contents are washed with water. If any of the acid has escaped decomposition, it may be removed by boiling the mass with a solution of potash or soda. After this treatment and due desiccation a powder will remain, having the characteristic colour and properties of boron." 297. Boracic acid, which is used in medicine, is generally ob- tained from the decomposition of borax by sulphuric acid. It may be crystallized in the form of small shining plates or scales, in which state it is combined with water, constituting a hydrate; but by exposure to a strong red heat, it melts into a hard trans- farent glass ; and at a white heat it becomes slowly sublimed, n the state of hydrate its specific gravity is 1.48, and in that of glass about 1.8. It dissolves sparingly in water, and the solution Describe Dr. Hare's method of obtaining boron. What changes m ly boracic acid be made to undergo by heat I 116 CHEMISTRY. reddens vegetable blues, like other acids ; but when applied to paper wetted with infusion of turmeric, it acts like an alkali, ting- ing it brown. The solution of boracic acid in alcohol burns with a green flame. This acid is found naturally in the hot springs of Sasso, in Tuscany, and also in the Lipari Islands ; and it like- wise occurs combined with magnesia in the mineral called boracite. 298. Boron may be made to combine with chlorine, by passing that gas over charcoal and boracic acid in a state of incandescence. The chloride of boron thus formed, is a gas, which may be collected over mercury. It is colourless, heavier than air, and emits fumes when exposed to air; but does not undergo decomposition when strongly heated. 299. A gaseous acid called the lorofluoric acid, was obtained by the French chemists, Gay Lussac and Thenard, by heating together vitrified boracic acid and fluor spar (fluoride of calcium.) In this process the oxygen of the boracic acid appears to enter into union with the calcium of the spar, forming oxide of calcium, and the fluorine being thus set free, unites with the boron to form the acid gas. It is colourless, but has a powerful smell, like muriatic acid ; is highly deleterious when respired, and extinguishes flame. It has an acid taste, and strongly reddens vegetable blues. It instantly carbonizes animal and vegetable substances, but it has no effect upon glass; thus exhibiting a striking dissimilarity with the hydrofluoric acid. When mixed with oxygen gas it is not decomposed, but it powerfully attracts moisture; and hence when bubbles of it are allowed to escape into the air, a dense white cloud is produced, arising from the combination of the borofluoric acid with the hygrometric water of the atmosphere. Silicon. 300. This is a peculiar solid body, hitherto undecomposed, and therefore considered as elementary, which in the state of combi- nation with oxygen is one of the most abundant substances in nature. Sir H. Davy appears to have effected the decomposition of the oxide, or rather acid of silicon, (siliceous earth,) by means of Galvanism ; but he was unable to collect the product of the operation so as to ascertain its properties. 301. Berzelius separated the silicon from its acid by means of Iron, and his experiments were repeated by Professor Stromeyer ; and the former at length succeeded in procuring silicon in an uncombined state. The process which he recommends is r.ot Where is it found in nature I What compound does it form with chlorine ? What are its properties ? How is borofluoric acid obtained ? What effect has borofluoric acid on vegetable and animal substances? What effect has it on atmospheric air ? What is the true chemical character of siliceous earth ? Who first procured silicon so as to exhibit it in a separate state ? SILICIC ACID. 117 difficult, and its efficacy depends on the affinity of potassium for oxygen, which it attracts when the double fluate of silica and potassa is heated nearly to a red heat in a glass tube closed at one end ; fragments of potassium being then introduced into the tube and made to mix with the fused salt, heat is again applied, and a feeble detonation ensues. The mass must then be left to cool, and the product being thrown into cold water, hydrogen is disengaged from the action of the siliciuret of potassium, which becomes con- verted into hydruret of silicon and potassa. 302. The hydruret thus obtained being heated in a platina cruci- ble, the hydrogen will be driven off, and the silicon will remain, in the form of a snuff-coloured or nut-brown powder. It does not burn either in air or oxygen gas ; neither is it fused or at all changed by exposure to powerful heat. 303. Silicic acid. Silicon, though thus incombustible, may be indirectly united with oxygen by various methods, forming, as already observed, the body known as siliceous earth. The com- bination may be effected by mixing silicon with dry carbonate of potassa, and exposing it to red heat, when the oxygen of the car- bonic acid will unite with the silicon, and a combination of silicic acid and potassa will be formed. If fused nitrate of potassa be used instead of the carbonate, no effect will take place ; though the addition of a little dry carbonate of potassa occasions imme- diate deflagration. 301. This peculiar phenomenon is owing to the influence of the alkali, which having a strong affinity for silica, disposes the silicon to combine with the oxygen of the carbonic acid, in which the union between carbon and oxygen is but weak. Nitric acid, on the contrary, being a very strong acid, entirely prevents the alkali of the nitrate from acting on the silicon ; unless the substances be heated to whiteness, and then the nitric acid becoming decom- posed, the silicon will attract its oxygen, and rapid combustion will take place. 305. When silicon is heated with caustic potassa or soda, it burns in the oxygen of the water which they contain, forming siiica. This substance may be found nearly pure in colourless rock crystal or quartz ; and in flint the earth is only combined with a little iron. In order to obtain silica in a state of absolute purity, rock crystal may be reduced to powder by heating it red- hot, and throwing it into water, and then bruising it in a mortar : one part of this powder is to be fused in a silver crucible, with three times its weight of potassa, and the mass thus formed being dissolved in water, muriatic acid is to be dropped into the solution so long as any precipitate is produced ; the liquid is then to be poured off, and the precipitate, which is acid of silicon, must be repeatedly washed with distilled water, and then dried. What process does Berzelius recommend for procuring silicon? How may silicic acid be formed ? How is the process accounted for ? What happens when silicon is heated in caustic potash ? How is pure silica obtained ? 118 CHEMISTRY. 306. Silica thus obtained is a white, tasteless powder, feeling harsh when rubbed between the fingers. It is nearly insoluble in water, and probably in all acids, except the hydrofluoric. It is infusible alone before the blowpipe, unless the flame be fed with oxygen gas, when it melts with difficulty into a colourless globule. Though water has no action on it after it has been dried, yet, according to Kirwan, when first precipitated and still moist, it dissolves in a thousand parts of distilled water; and it is certain that nature has some process for the solution of this substance, since it is found, though in minute proportions, in the water of some hot springs, as the Geysers in Iceland. When first prepared and minutely divided, it readily dissolves in solutions of potassa or soda ; but ammonia has no effect on it. 307. When silica is fused with a large portion of potassa, a compound is produced readily soluble in water, forming the liquor silicum, liquor of flints, of old writers. Professor Seigling, of Erfurdt, having prepared this liquor with aJarge quantity of water and of alkali, he suffered it to stand for eight years in a glass vessel, covered with paper, when crystals of salts of potash were formed at the bottom of the vessel, and the remaning liquid, about two ounces, was covered by a transparent crust, consisting partly of carbonate of potash, and partly of crystallized silica : the latter so hard as to strike fire with a steel. 308. When silica is fused with a small proportion of potash or soda, without water, the product is that useful substance glass. In the manufacture of glass a variety of other substances are oc- casionally added to the silica and alkali, for various purposes : among these may be mentioned black oxide of manganese, which renders glass colourless, and improves its transparency ; litharge or oxide of lead, used in making what is called flint glass; lime, which is added to the ingredients for crown or the best win- dow glass ; and boracic acid or borax, employed in making arti- ficial gems. White arsenic, nitre, brick clay, and other sub- stances are sometimes added to improve the quality of glass ; or in the coarser kinds, to increase the quantity. 309. Silica was long classed among the earths from which it differs decidedly, in not forming salts with acids ; the hydrofluoric acid, as already observed, being the only one with which it enters into combination. Hence it appears that' silica cannot act the part of a base like the alkalies, earths, and metallic oxides. With several of these, however, it is found combined in various minerals, and therefore as to its mode of action it has an obvious analogy with acids, and some chemists have given it the name of silicic acid, instead of silicic oxide : and to the compounds formed by its union with several earths and metallic oxides, they have What are its prominent properties ? Where does it exist in natural solution ? How is the liquor of flints obtained ? Into what artificial product does silica enter? In what respect does silica differ from other earths ? PHOSPHORUS. 119 applied the designation of silicates; and thus glass might be con- sidered as a silicate of potassa or soda. 310. Among the combinations of silicon with the elementary substances, may be mentioned those that it forms with chlorine and with fluorine. When silicon is heated in chlorine, as when a current of that gas is made to pass over red-hot silicon in a porcelain tube, a fuming liquid is obtained of a yellow colour, extremely volatile and irritating, which when exposed to moisture becomes decomposed forming muriatic acid and silica. This is the chloride of silicon. When potassium is heated in the vapour of this chloride, it burns, with the production of siliciuret and chloride of potassium. 311. Silicofluoric acid, or fluoride of silicon, may be made by distilling in a retort three parts of fluor spar and two of powdered silica, with an equal weight of sulphuric acid, when a gas will be produced which may be collected over mercury. Water must be carefully excluded in this operation, therefore the apparatus must be made quite dry. Silicofluoric acid is a colourless gas, having a pungent smell, much like that of muriatic acid, and a very sour ste. It is more than 3^ times the weight of common air. It extinguishes the flame of a taper, and forms white fumes when exposed to moisture, being readily absorbed by water; from which, however, silica is precipitated, hydrofluoric acid being produced. If the beak of a retort from which this gas is issuing be plunged beneath water, it soon becomes choked by the abundant deposition of hydrated silica, which sometimes forms tubes through the water, by which the gas passes off into the air. Silicon likewise unites with sulphur, and with several of the metals, especially platina and iron. Phosphorus. 312. This body being highly inflammable, and consequently having a strong affinity for oxygen, seldom occurs naturally ex- cept in combination with that element, constituting phosphoric acid united with some base, in the state of a salt. It is thus found in the bones of animals, the denser parts of which consist principally of phosphate of lime, or the combination of lime with phosphoric acid, and from the decomposition of this earthy salt phosphorus is procured. The usual process is to digest a quantity of calcined or burnt bones, reduced to powder, in half their weight of strong sulphuric acid. The phosphate of lime is thus decom- posed, and the phosphoric acid, after being separated from the lime, undergoes a further decomposition by being mixed with powdered charcoal, and strongly heated in an earthen retort, How is silicon made to combine with chlorine ? How can it be combined with fluorine ? Enumerate the properties of fluoride of silicon ? With what metals is silicon capable of combining ? In what combination is phosphorus found in nature ? What is the usual process for procuring phosphorus ? 120 CHEMISTRY. when the charcoal will combine with the oxygen of the acid, and the phosphorus passing over, may be received in a vessel of water, under the surface of which the beak of the retort must be plunged. The process is troublesome, and requires much atten- tion on the part of the operator. 313. Phosphorus thus obtained is a flesh-coloured, slightly- transparent solid, nearly the consistence of wax ; which, on account of its inflammability, must be preserved under water. If heated in water, it melts at about 110 Fahrenheit, and boils or becomes evaporated at 550. When exposed to the atmosphere at common temperatures, it emits a light smoke, and a peculiar odour, resembling that of garlic, giving out in the dark a beauti- ful pale-green light. In this case it undergoes a slow combustion. It is soluble in essential oils, and communicates to them the pro- perty of shining in the dark. In pure nitrogen gas it is not luminous, undergoing no alteration at any temperature. But it appears that the smallest possible quantity of oxygen will suffice to produce some degree of combustion ;* for it will burn, or at least give out light in the exhausted receiver of an air-pump. Phos- phorus may be set on fire by friction at a low temperature, and at about 100 it takes fire, and burns with intense brilliancy, throw- ing off abundance of white fumes. 314. This substance combines with oxygen in different propor- tions. Oxide of phosphorus is a white substance with which phos- phorus becomes covered when kept for some time under water. It is very inflammable, and may be used in making phosphoric match-boxes. For this purpose a piece of phosphorus must be introduced into a small phial, melted slowly by applying heat ex- ternally, and stirred about with a hot iron wire till the inside of the bottle becomes coated with the semi-fluid oxide, which is then What are the sensible properties of phosphorus ? At what temperature does'it melt ? At what point does it evaporate ? By v/hat mechanical means may phosphorus be ignited ? What is the name given to the combination of phosphorus with oxygen in the lowest proportion ? To what useful purpose may this compound be applied ? What effect is observed on placing phosphorus in a vacuum ? * It appears from the experiments of Dr. John Davy and others, that "when oxygen gas is rarifiedjj>hospho.rus shines in it: and that when condensed it ceases to shine. With an augmented pressure of a column of mercury of 16 inches, when heated with a spirit-lamp in this gas, it emitted no light till it fused ; then it burst into flame and burnt explosive- ly, and the oxygen was condensed in an instant Compression and rarefaction, in the instance of common air, has an effect analogous to that mentioned when speaking of oxygen When phosphorus is placed on the plate of an air-pump, under a receiver, and the air exhausted, the brightness of its light in the dark rather increases with the exhaustion ; and in the nearly perfect vacuum formed by a good pump, its light was not diminished. When the air has been suddenly readmitted, the light has been extinguished, and for a few seconds it has ceased to shine." Obser- vations on Phosphorus. By J. Davy, M. D-, F. R. S., in Jameson's Journal of Science. PHOSPHORIC ACID. 121 to be preserved for use, by closing the bottle with a cork. When a light is wanted, it is only necessary to dip into the bottle a brimstone-match, and on withdrawing it with a small portion of the oxide of phosphorus adhering to its extremity, the sulphur will become inflamed, and the match may be used for lighting a taper or for any other purpose. 315. There is some uncertainty as to the number of the acid combinations of phosphorus and oxygen. Three may be discri- minated as containing different proportions of their constituent elements. These are the hypophosphorous, the phosphorous, and the phosphoric acids. The relative quantities of phosphorus and oxygen in these acids are thus stated by Mitscherlich : Phosphoric acid = 100 Phosphorus + 127.450 Oxygen. Phosphorous acid = 100 Phosphorus-}- 76.470 Oxygen. Hypophosphorous acid = 100 Phosphorus -j- 25.490 Oxygen.* 316. The phosphorous acid is a white, volatile substance, which may be obtained by burning phosphorus in a tube, with a relatively small portion of air, and at a moderate temperature ; it may then be collected in the state of a white powder, which, on exposure to the, atmosphere, decomposes the water suspended in it, con- siderable heat is given out, and it combines with an additional portion of oxygen to constitute phosphoric acid. The phosphorous acid speedily dissolves in water, to which it gives a sour taste, and the solution reddens vegetable blues. With various salifiable bases this acid forms certain salts called phosphites. Both the phosphorous and the phosphoric acids combine in definite propor- tions with water, forming hydrated acids. 317. When phosphorus is rapidly inflamed, as in its combus- tion in oxygen gas, abundance of white vapours are produced, which become condensed into deliquescent flakes, adhering to the interior of the receiver, or falling to the bottom like snow ; this substance is the phosphoric add. This acid may also be obtained from the decomposition of atmospheric air by phosphorus. Thus if a piece of phosphorus be placed in a watch-glass, upon a plate of glass, and covered with a tall receiver, on setting it on fire with a red-hot iron it will at first burn rapidly, and then more slowly till the oxygen is nearly consumed. The combustion, however, may be renewed by occasionally lifting the receiver slightly, so as to introduce fresh supplies of air from time to time, till the phos- How many acid compounds of phosphorus and oxygen are known to exist? What are the relative proportions of the two ingredients in each? What are the leading properties of phosphorous acid ? In what manner is phosphoric acid formed ? How is it obtained in an anhydrous state ? * Introduction to Chemistry, vol. i. p. 389. L 122 CHEMISTRY. phorus is all burnt, and thus will be formed a quantity of anhy- drous phosphoric acid, as before, in the form of flakes of snow. 318. This substance dissolves in water with a hissing noise, and the evolution of much heat; and it is also soluble in alcohol. Phosphoric acid may likewise be obtained by heating small frag- ments of phosphorus in nitric acid. Though phosphoric acid will unite readily with water, on heating the solution the greater part of the water may be driven off, and if the residue be exposed to a low red heat it melts, and on cooling forms a kind of glass, some- times called glacial phosphoric acid. The solid acid attracts water from the air; it has no smell, but an intensely sour taste, and becomes volatilized without decomposition at a bright red heat. It unites with salifiable bases to produce the salts called phosphates, one of which, the phosphate of soda, is used in medicine ; and phosphate of lime, or the combination of this acid with calcareous earth, constitutes a considerable part of the bones of animals, from the decomposition of which, as already stated, phosphorus is usually obtained. 319. The hypophusphorous acid, is so named as containing a smaller proportion of oxygen than the phosphorous acid. The salts formed by this acid are all readily soluble, and highly deliques- cent when exposed to the air. 320. The phosphoric acid is capable of undergoing modifica- tions, which materially influence its properties, without causing any alteration of the proportions of its constituents. " If liquid phosphoric acid be exaporated, and heated to such a temperature as may be judged capable of expelling the chief part of the water, it is changed into pyrophosphoric acid : and the same change takes place when the acid exists in a salt combined with an alkali. Although between phosphoric and pyrophosphoric acid there is no known difference of composition, the properties of each are essentially different. Pyrophosphoric acid produces, with oxide of silver, a white salt ; phosphoric acid, a yellow one : the former is a less energetic acid, it has less saturating power, and is even separated from its combinations by phosphoric acid."* 321. This apparent identity of composition occurs in various other compounds, constituting the phenomenon which has been How is phosphoric acid obtained in a glacial state? What are ihe chief properties of this acid ? In what form of combination does phosphorus exist in animals? What changes may phosphoric acid undergo without changing the pro- portions of its constituents ? What striking difference exists between phosphoric and pyrophosphoric acid t * Donovan's Treatise on Chemistry, in Cabinet Cyclopaedia, p. 221. See also Mitscherlich's Introduction to Chemistry, vol. i. pp. 391 394 ; and Johnston on Chemistry, in Report of British Association for 1832, pp. 457 PROTOCHLORIDE OF PHOSPHORUS. 123 termed Isomerism.* Another instance of it will be found in the combination of phosphorus with hydrogen, in the existence of two oxides and two chlorides of tin, differing in properties, but having the same atomic constitution, in some other combinations of oxy- gen with metals, and in some of the acids with compound radicals. Among the numerous carburets of hydrogen, cases of a corre- sponding mode of union have been noticed, giving rise to what is termed Polymerism;* and there is another kind of relation be- tween the combining proportions of bodies expressed by the term Metamerism.* These phenomena have so much similitude, that their origin may with probability be referred to a common cause ; but the subject, which is highly interesting, requires further in- vestigation. 322. Phosphorus combines with chlorine in two proportions. Protochloride of phosphorus may be obtained by distilling phos- phorus mixed with corrosive sublimate, or perchloride of mercury, when calomel, or protochloride of mercury will be formed by the decomposition of the sublimate, and the portion of its chlorine, which is thus set free, will immediately combine with the phos- phorus. Protochloride of phosphorus when first obtained, is a liquid of a reddish colour, holding some phosphorus in solution, which it deposits on standing. It then becomes transparent and colourless. Its specific gravity is 1.45. It has a suffocating smell, and gives off acid fumes when exposed to the air, owing to its absorbing w r ater, which it readily decomposes, the hydrogen of the water combining with chlorine to form muriatic acid, and the oxy- gen with the phosphorus to form phosphorous acid. Its vapour is combustible ; and when in a dry state, it does not affect the colour of vegetable blues. To what phenomenon is the term Isomerism applied ? What is meant by Polymerism ? Metamerism ? What two compounds are formed by phosphorus and chlorine? Describe the process of obtaining the prolochloride of phosphorus? What are its properties ? * Isomerism is a term derived from the Greek "Iffoj, equal, and a part ; Polymerism from IIoXvs, many, and Mepoj; and Metamerism from Mer/l, according to, and Mcpoj. The following explanation of these terms is given by Mr. Johnston: " Isomeric bodies are those which contain the same absolute and relative number of atoms of the same elements, and have consequently the same atomic weight. Polymeric are those which contain the same relative, but not the same absolute number of atoms of the same elements, and whose atomic weights are consequently unlike. Metameric are those which, while ihey contain the same absolute and the same relative number of atoms of the same elements, yet constitute sub- stances belonging to an entirely different class of bodies, or a different or- der of chemical compounds." Reports of the British Association for 1832, pp. 435, 436. Isomorphism, (from the Greek "In>y, and Mop 9 n ~ O v Peroxide of U.J 2U ' 3 Sulphuret of U., 2 U. 3 S. What are the names and constituents of the compounds of chrome ? of molybdenum ? of tellurium ? of tungsten ? of vanadium? of uranium ? ARSENIC. 139 Manganese. I Man. 1 Ox. 1 Man. 2 Ox. Oxides of M.^' 2 Man. 3 Ox. 3 Man. 4 Ox. Man. 7 Ox. Manganeseous acid, 1 Man. 3 Ox. Manganesic acid, 2 Man. 7. Ox. Chloride of M., 1 Man. 1 Ch. Perchloride of M. Sulphuret of M., 1 Man. 1 S. Cobalt. Oxide of C., I Cob. 1 Ox. Peroxide of C., 2 Cob. 3 Ox. Cobaltic acid, 1 Cob. 2 Ox. Chloride of C., 1 Cob. 1 Ch. Sulphuret of C., 1 Cob. 1 S. Persulphuret of C., 1 Cob. 2 S. Tin. Oxide of T., 1 Tn. 1 Ox. Stannic acid, or}. T Q o Peroxide of T. $ l Hemichloride of T., 2 Tn. 1 Ch. Chloride ofT., 1 Tn. 1 Ch. Bichloride of T., 1 Tn. 2 Ch Sulphuret of T., 1 Tn. 1 S. Bisulphuret of T., 1 Tn. 2 S. Phosphuret of T., 3 Tn. 2 Ph. 36G. Jlrsenic. The substance popularly known under the desig- nation of arsenic, is the arsenious acid, one of the compounds of the metal with oxygen. In the metallic or uncombined state arsenic is of a grayish-white colour, shining brightly when untarnished ; but as it readily attracts oxygen from the air, its surface soon becomes dull when exposed to it ; but it will retain its lustre if kept under water or alcohol. It is moderately hard, and very brittle. Arsenic fuses readily, and becomes volatilized if heated in a close vessel to about 360. When thrown on a red-hot iron, or otherwise heated in contact with atmospheric air, it burns with a blue flame, subliming in the form of a white vapour, having an odour like garlic. The sublimate, when cooled, crystallizes in octaedrons, consisting of arsenious acid, formerly called white oxide of arsenic. 367. This substance, well known as a most virulent poison, What are the names and constituents of the compounds of manganese ? of cobalt? of tin? What is the true chemical nature of while arsenic? What are the properties of metallic arsenic ? 140 CHEMISTRY. generally occurs in the state of a compact saline mass, or heavy white powder. It is very sparingly dissolved by cold water; but 100 parts of the boiling water will dissolve 7.77 parts of the acid, more than half of which remains suspended after the liquid be- comes cool. The arsenic acid, which is a deliquescent, colourless substance, is also poisonous. Arseniuretted hydrogen is a strongly poisonous, inflammable gas. Both the sulphurets of arsenic oc- cur as native minerals. Arsenic becomes inflamed when introduced in a divided state into chlorine gas, and burns with great splendour. 368. Antimony. What is termed crude antimony in commerce is the sulphuret of this metal, which is found in the native state. Metallic antimony is a shining, hard, and brittle substance, some- what the colour of silver. It has a laminated and imperfectly crystalline texture. When exposed to the air it loses its lustre, but is otherwise little altered. If rubbed on the fingers, it gives out a peculiar smell and taste. It becomes fused at 810, and sublimes in a white heat, combining with oxygen. The powdered metal takes fire when thrown into chlorine gas, and burns with a bright white flame. The product is a liquid, which becomes con- crete at common temperatures, constituting the chloride, formerly named, from its consistence, butter of antimony. The perchloride is a volatile, transparent, fuming liquid. Several preparations of this metal are used in medicine, of which the best known and most valuable is emetic tartar, or antimoniated tartrate of potash. 309. Columbium. This is a dark gray metal, very difficult of fusion, and extremely hard and brittle. It is not altered by ex- posure to the air ; but it burns at a red heat, forming a whitish oxide. It is scarcely at all soluble in any of the acids except the fluoric, in which it dissolves with the evolution of heat, and the disengagement of hydrogen gas. 370. Titanium. Dr. Wollaston found this metal in the slag of an iron furnace at MerthyrTydvil, in South Wales, in the state of small cubic crystals, of a red or copper colour, and so hard as to scratch rock crystal. It is infusible by a common blowpipe, but becomes oxidated by continued heat, a purple film forming on its surface. No acid acts on it ; but if it be heated with nitre, oxidation readily takes place. The oxide of titanium has been used for painting on porcelain. What form has the poisonous compound when crystallized ? In what proportion is it soluble in boiling water? How does metallic arsenic react with chlorine ? Jn what form is antimony found in commerce ? What are the characters of true metallic antimony ? At what heat does it sublime ? What is butter of antimony ? For what purpose is antimony employed in medicine and in what form? What are the exterior appearances of columbium ? How is it affected by air and heat ? What solvent can act upon this metal ? Where and by whom was titanium discovered ? State its chemical character and relations. TUNGSTEN. 141 371. Chrome, or Chromium. This metal obtained its name from the varied colours of its salts.* It is a white and very brittle metal, susceptible of a high polish, and, according to Richter, slightly magnetic. It can be fused but imperfectly at a very high tempera- ture. No acids appear to act on it except the fluoric, which dis- solves it readily. When heated with nitre it combines with oxy- gen, forming chromic acid. This acid is of a deep red colour; and the oxide of chrome exhibits a green colour. Some of the coloured gems owe their beautiful tints to this metal ; and it fur- nishes some fine pigments for enamel painting and calico-printing. 372. Molybdenum. This metal is said to have been obtained in the state of small grains, of a brittle texture, and of a light gray colour ; but it may be questioned whether it has undergone per- fect reduction, as it is exceedingly difficult of fusion. When heated in contact with oxygen gas, or atmospheric air, it becomes converted into a white crystalline sublimate, which is the molyb- dic acid. 373. Tellurium. This is one of the most important of the acidifiable metals, the nature and properties of which have been illustrated by the elaborate researches of Berzelius.f The metal is of a bright gray colour, and has a foliated texture : it is brittle, readily fusible, and very volatile. When heated to full redness in a close vessel, it sublimes in the form of a yellow gas, which condenses in drops, and becomes crystallized on cooling. The smell of its vapour is peculiar, slightly resembling that of sele- nium.ij: Tellurium is soluble in the nitric and the nitro-muriatic acids. Its combination with oxygen in the proportion of 1 T.+2 Ox. forms an acid capable of existing in two states, the tellurous acid and the paratellurous acid ; and the compound of 1 T.-f-3 Ox. has corresponding properties, forming the telluric and the para- telluric acids. The combination of tellurium with hydrogen is a gas, which, like sulphuretted hydrogen, manifests the properties of an acid. 374. Tungsten. This metal is distinguished for its specific gra- vity, being about 17^ that of water. It is of an iron-gray colour, very hard, brittle, and difficult effusion. When heated in atmospheric Whence does chromium derive its name ? What is its appearance? How is chromic acid produced ? For what purposes is it employed in the arts ? What change have chemists been able to produce on molybdenum ? For what properties is tellurium distinguished ? In what substances is it soluble ? By what circumstance is tungsten distinguished ? * From the Greek Xpu t See Johnston on Chemistry in Report of British Association, 1832, p. t Id. p. 472. The odour of this metal, or rather of the vapour of tellu- rous acid, has been compared with that of radishes. See Children's Essay on Chemical Analysis, p. 67. $ Id. pp. 472, 473. 142 CHEMISTRY. air, it combines with oxygen to form tungstie oxide, a brown or chocolate-coloured powder. This oxide exposed to a red heat, and agitated in an open vessel, absorbs more oxygen, and becomes tungstic acid, which is a yellow powder, but acquires a greenish hue by long exposure to the rays of the sun. 375. Vanadium. The properties of this metal most nearly cor- respond with those of chrome, and in a natural arrangement of the metallic elements, it might be placed between chrome and molybdenum. In colour and lustre it resembles the latter me- tal. "It is characterized by giving, in the form of an oxide, blue salts with acids; with oxygen forming a peculiar acid, which fuses at a red heat without decomposition, and on cool- ing is reddish-brown and crystalline, and which gives with bases colourless neutral and orange-coloured acid salts. Before the blowpipe it behaves itself like chromium, with this charac- teristic difference, that the green colour with borax can in the oxi- dizing flame be changed into a pale yellow.* 376. Uranium. This metal is of a grayish-brown colour, pos- sessing considerable lustre, brittle, and very difficult of fusion. It does not tarnish in the air at common temperatures, but when made red-hot in an open vessel, it becomes oxidated, forming a dark green or blackish powder. The compound of 2 U. -\- 3 Ox., is a yellow powder, used in painting porcelain, arid which acts as an acid, forming a salt with barytes. 377. Manganese. This metal in some of its properties, resem- bles iron. It may be obtained by exposing the black oxide, with charcoal powder and oil, to a most intense heat in a wind furnace, and the metal will then be found in small globules, or in the form of an imperfect button, at the bottom of the crucible. It is of a dusky-whitish colour, and finely granular texture, softer than cast iron, and very brittle. It is difficult of fusion, and is readily acted on by the air, tarnishing, and at length crumbling into a brown powder. When heated in oxygen gas, it undergoes combustion, and it decomposes the vapour of water at a red heat. The per- oxide, 1 M.-J-2 Ox., from its colour styled black oxide of manga- nese, is frequently found native, and is the general source from which the metal and its compounds are procured. No change is produced on it by exposure to the air, but the variety of native oxide, called black wad, has the property of spontaneous inflam- What compounds of this substance are formed with oxygen ? To what metals is vanadium most nearly related ? What two (Species of compounds does it form with oxygen ? What is the colour of uranium ? What compound of this metal is employed ^n the arts and for what pur pose? How is manganese procured ? What effect has air on this metal ? What ingredient does manganese derive from water ? * See Johnston's Rep. on Chem., p. 469. TIN. 143 mation, when well dried, and kneeded with linseed oil. It is in- soluble in water, and does not combine with acids or alkalies ; but such acids as appear to dissolve it, reduce it to the state of protox- ide, with which salts are formed. 378. When the peroxide of manganese is mixed with an equal weight of nitrate of potash, and exposed to a red heat, a green mass is obtained, which being put into water, furnishes a solution, the colour of which successively becomes green, blue, purple, and red, and ultimately disappears entirely ; whence it has been called the chamelion mineral. The experiment may be varied by putting equal quantities of the mixture of the peroxide and nitre into two glasses, and pouring on one hot, and on the other cold water, when the former solution will exhibit a fine green colour, and the latter a deep purple, and the shades will vary with the alteration of temperature.* 379. Cobalt. The metallic nature of this substance was first recognized about one hundred years ago, but its oxide has been used in making coloured glass since 1540. Cobalt is of a red- dish-gray colour, and a fibrous or laminated texture, brittle, and difficultly fusible. Like iron and nickel, it may be rendered mag- netic. Neither air nor water acts on it at a low temperature, but when heated to redness in an open vessel, it forms an oxide of a very deep blue colour, and if the heat be intense, the metal takes fire and burns with a red flame. The chloride of cobalt, combined with water, forms Hellot's sympathetic ink, which may be pre- pared by digesting the oxide of this metal in muriatic acid, and adding water till the liquid becomes of a pale rose colour. Any thing written on paper with a clean pen dipped in this solution, will be invisible till it is slightly heated, when the writing will appear of a bright green tint, which vanishes as the paper cools, and may be renewed at pleasure ; but if once strongly heated, the characters become permanent. Acetate of cobalt (the salt formed by oxide of cobalt and acetic acid) dissolved in water constitutes an excellent sympathetic ink, which may be used like the preced- ing; but it gives to paper a beautiful azure instead of a green tint when heated. The oxide of cobalt, in combinations with si- licic acid and potash, forms smalt, and other blue pigments used in the arts. 380. Tin. This is one of the metals which appear to have been known to the ancient Greeks and Romans, who obtained it What is the nature of the action of acids on the black oxide of manga- nese? How is chameleon mineral obtained ? How may the influence of temperature on chemical effects be illustrated by this substance ? How long has cobalt been known as a metal ? What temperature is necessary to effect its combustion ? What is the composition and use of Hellot's sympathetic ink ? What other compound of cobalt produces similar effects? * See Johnston's Rep. on Chem., pp. 477, 482 144 CHEMISTRY. from Spain and Britain. Its general appearance is well known, tin-plate, consisting of sheets of iron coated with tin, being used for a multiplicity of purposes ; and tinfoil, (leaf-tin,) employed to line tea-chests, and wrap up articles which require to be pro- tected from the air. Tin is not very hard nor ductile, but ex- tremely malleable ; and when sheet-tin is bent suddenly, it emits a peculiar sound, called by the French cri d'etain : this metal has also a characteristic odour, and a faint but disagreeable taste. It is not affected by water at common temperatures, but becomes tarnished by exposure to the air. If steam be passed over tin heated to redness, it decomposes the water, absorbing oxygen, and the hydrogen is. given off in the gaseous state. The compound of 1 T. + 2 Ox., called peroxide of tin, is capable of combination with alkalies, thus manifesting the properties of an acid. When fused with glass, it forms a milk-white enamel, useful for technical purposes. 381. The substance called in commerce tin putty, is an impure oxide of tin. This metal burns in oxygen gas, when heated below its fusing-point, and it is soluble in the sulphuric, nitric, and muriatic acids. Bichloride of tin is a colourless liquid, called the fuming liquor of Libavius, from its alleged discoverer, a chemist of the seventeenth century. Combinations of tin with chlorine are used in dying and calico-printing, and with the solu- tion of gold in nitro-muriatic acid, to form the purple powder of cassius, a pigment employed in ornamenting porcelain. The bisulphuret of tin is a substance of a shining yellow colour, and a flaky structure, which was formerly called Mosaic gold (Jlurum Musivum . ) Binary Combinations of the Metallic Elements of the Sec&nd Class with Oxygen and Chlorine. Potassium. Protoxide of P., (potash,) 1 Pm. 1 Ox. " Peroxide of P., 1 Pm. 3 Ox. Chloride of P., 1 Pm. 1 Ch. Sodium. Protoxide of S., (soda,) 1 Sod. 1 Ox. Peroxide of S., 1 Sod. 2 Ox. Chloride of S., (marine salt,) 1 Sod. 1 Ch. What properties does tin possess in a high degree ? How does it react on the vapour of water ? What compound of tin manifests acid properties ? What is meant by tin putty ? What peculiar characters has the perchloride of tin ? What was it formerly called ? Of what is powder of cassius composed ? What is the nature of Mosaic gold ? Repeat the list of metallic elements of the second class. What are the compounds formed with potassium ? with sodium ? POTASSIUM. 145 Lithium. Oxide of L., (lithia,) 1 L. 1 Ox. Chloride of L , 1 L. 1 Ch. Baryum. Protoxide of B., (barytes,) 1 B. 1 Ox. Peroxide of B., 1 B. 2 Ox. Chloride of B., 1 B. 1 Ch. Calcium. Protoxide of C., (lime,) 1 Cal. 1 Ox. Peroxide of C., 1 Cal. 2 Ox. Chloride of C., (muriate of lime,) 1 Cal. 1 Ch. Strontium. Protoxide of S., (strontia,) 1 Str. 1 Ox. Peroxide of S., 1 Str. 2 Ox. Chloride of S., 1 Str. 1 Ch. Magnesium. Oxide of M., (magnesia,) 1 Mag. 1 Ox. Chloride of M., 1 Mag. 1 Ch. Aluminum. Oxide of A., (alumina,) 2 Al. 3 Ox. Chloride of A., 2 Al. 3 Ch. Zirconium. Oxide of Z., (zircon earth,) 2 Zir. 3 Ox. Glucinum. Oxide of G., (glucina,) 2 Gl. 3 Ox. Yttrium. ^ Oxide of Y., (yttria,) 1 Y. 1 Ox. Thorium. Oxide of T., (thorina,) 1 Th. 1 Ox. 383. Potassium. This metal is the basis of potassa, or, as it was formerly called, the fixed vegetable alkali, which was dis- covered by Sir H. Davy to be protoxide of potassium. It may be procured by placing a thin plate of pure caustic potash, slightly What are the compounds formed with lithium? baryum ? calcium? strontium ? magnesium ? aluminum ? zirconium ? glucinum ?--yttrium ? thorium ? What is the chemical nature of potassa ? 146 CHEMISTRY. moistened, between two disks of platina, connected with the op- posite wires of a powerful Voltaic battery, when the alkali will become fused and afterwards decomposed, its oxygen being evolved at the positive wire, while the metal, in small shining globules, will make its appearance at the surface connected with the negative wire. Potassium may also be obtained by passing melted potash through a red-hot gun-barrel, containing fragments of iron, which, at a very high temperature, will decompose the alkali, by attracting its oxygen, and thus the metal will be set free as before. The affinity of this metal with oxygen is so great, that it decomposes most bodies which contain it, even at very low temperatures ; and hence when potassium comes in contact with atmospheric air or water, it immediately absorbs oxygen from either of those fluids, and protoxide of potassium or .potash is thus produced. Potassium, therefore, cannot be preserved without being secured from the contact of air and water ; but it may be kept immersed in ether, or included in exhausted glass tubes hermetically sealed. 384. Potassium at 32 Fahrenheit, is a hard, brittle solid, of a crystalline structure, and of a white colour, like silver. At about 50 it becomes malleable and ductile, having nearly the consistency of soft wax, and in that state its specific gravity is about 0.85 ; at 150 it is perfectly fluid, and at a bright red heat it sublimes without decomposition, in the form of a green vapour. It is a good conductor, both of heat and electricity. When this metal is heated in air or oxygen gas, it burns with a brilliant white flame, and is converted into an orange-coloured substance, which, on cooling, appears in the state of crystalline scales. This is the peroxide of potassium. The protoxide of potassium, or caustic potash, has a most powerful affinity for water, which it readily absorbs from the air; and thus forms a definite compound, called hydrate of potash, composed of 1 potash -f- 1 water. 385. The common potash and pearlash of the shops consist of this alkali combined with carbonic acid, forming carbonate of potash. This salt is commonly obtained by evaporating the ley produced by steeping wood-ashes in water. The decomposition of the carbonate of potash is effected by means of caustic lime, which having a stronger attraction for carbonic acid than potash has, it attracts the acid, and sets free the alkali in the state of hydrate of potash. This substance, when purified, is white, acrid, How is its metallic base procured ? In what manner may it be obtained from the reaction of potassa with iron? In what manner must potassium be preserved ? Why ? What characters does potassium exhibit at low temperatures? At what temperature does it become ductile ? What is its melting point ? At what point is it vaporized ? What compounds does potassium form by combustion in oxygen ? What is the chemical nature of pearlash T ? SODIUM. 147 and corrosive, destroying the texture of animal and vegetable sub- stances. It speedily absorbs moisture and carbonic acid from the air, but it may be crystallized in octaedrons, by keeping a strong solution of it in water for some time, in close vessels. It reddens substances coloured by turmeric, changes vegetable blues to green, and neutralizes acids without any effervescence. It enters into combination with fat oils, forming soft soaps. 386. When small quantities of potassium are introduced into chlorine gas, intense inflammation takes place, and the chloride is produced. This is a white saline substance, of a bitter, disagreeable taste, readily soluble in water, from which it may be procured by evaporation in cubic crystals. It was formerly sup- posed to be a compound of muriatic acid and potash, and it was long used in medicine under the names of digestive salt of Sylvius, and regenerated sea-salt. Potassium has a stronger affinity for chlorine than for oxygen, since both its oxides are decomposed by chlorine gas. 387. Potassium enters into combination with iodine and with bro- mine, and the iodide of potassium is sometimes used in medicine. Potassium also unites with hydrogen, sulphur, selenium, phos- phorus, and carbon, to form peculiar compounds. Alloys are formed by the combination of potassium with various other metal- lic bodies. The amalgam of potassium, or combination of this substance with mercury, may be readily formed, by mixing them together at the usual temperature of the air. This amalgam may also be produced by placing a thin mass of mercury in the bottom of a flat glass vessel, about two inches in diameter, and pouring over it a strong solution of caustic potash, then on connecting an iron wire from the negative pole of a Voltaic battery with the mercury, and a platina wire from the positive pole with the alkaline solution, into which it must be dipped so as not to touch the surface of the mercury, an amalgam will be formed with such rapidity, that more than 1200 grains of mercury will become combined into a solid alloy with the potash in twenty-four hours. This amalgam has the property of dissolving all other metals. Potassium like- wise combines with gold, silver, and copper; but when any of its alloys are thrown into water they become decomposed, potash being formed, which dissolves in the water, and the other metal is set free. 388. Sodium. This metal, which is the basis of soda or mineral alkali, greatly resembles potassium, both in its physical and chemical properties. It may be obtained from soda by similar processes to those already described for the decomposition of potash, only it is necessary to employ a stronger electric power, or a higher degree of heat. Sodium is a soft, malleable metal, How is the carbonic acid separated from carbonate of potash ? What are the compounds of potassium with chlorine ? What peculiar property has the amalgam of potassium ? What differendfe are observable between potassium and sodium? 148 CHEMISTRY. which does not become brittle like potassium at 32, since at thaft temperature globules of it may be welded together by pressure It is rather heavier than potassium, its specific gravity being 0.97. In colour it resembles lead, but tarnishes on exposure to a moist atmosphere. Its fusing-point is about 190, and it is volatile at a white heat ; but if heated in contact with air, it burns with a white light, accompanied with red sparks. In consequence of its powerful affinity for oxygen, it must, like potassium, be preserved under ether or naphtha. Soda, or the protoxide of sodium, com- bines with water, forming hydrate of soda, which is the mineral alkali or natron of commerce. 389. The combination of sodium with chlorine, (chloride of so- dium,) is the substance generally known as common or marine salt. This body, which exists largely in nature, especially in the state of rock-salt and in solution in sea-water, was formerly sup- posed to be a compound of muriatic acid and soda, and hence it was called muriate of soda. It is now known, however, to be a substance of a different class from the proper salts, or compounds of acids and alkalies, and, upon the whole, it may be considered as having a closer analogy with the alkalies than with the neutral salts. It may be produced artificially by heating sodium in chlo- rine gas, when the metal burns, forming a white compound, which is the chloride of sodium. This chloride becomes decomposed by heating it with potassium, and thus the sodium is set free and chloride of potassium produced. 390. If protoxide of sodium be exposed to heat, in chlorine gas, oxygen will be evolved, and chloride of sodium formed. When the protoxide is heated in hydro-chloric (muriatic acid) gas, a mutual decomposition will take place, and the products will be the chloride and water. The chloride of sodium crystal- lizes in regular cubes, which decrepitate, or fall into pieces with a crackling noise when heated ; and if the heat be raised to redness, the crystals fuse without decomposition, and on cooling become con- gealed into a hard white mass. This substance, though readily soluble in water, is almost insoluble in alcohol. Its general properties, and the numerous purposes to which it is applied, are too well known to require specification. 391. Sodium unites with iodine and bromine, and among the combustibles, with sulphur, selenium, and phosphorus, but not with hydrogen. It forms alloys with most, if not all, the metals. 392. Lithium. This is a metallic substance comparatively of rare occurrence, having hitherto been found only in the petalite, spodumene, lepidolite, some kinds of feldspar, and a few other minerals, and in certain waters in Bohemia. In these bodies it What \9 the melting point of sodium ? By what name is hydrate of soda known in commerce ? What is the true chemical nature of common salt ? What was it formerly supposed to be I How is common salt acted on by potassium, and what are the results ? With which classes of non-metallic bodies does sodium unite? In what substances is lithia found ? BARYUM. 149 exists in the state of an oxide, called lithia, which exhibits pro- perties partly resembling those of the earths, and partly those of the alkalies. The oxide of lithium may be decomposed, like pot- ash and soda, by Voltaic electricity, and the product is a brilliant white and highly combustible metallic substance, bearing much resemblance to sodium ; but its properties have hitherto been very little investigated, in consequence of the scarcity of its compounds. Chloride, iodide, fluoride, and sulphuret of lithium, have been ob- tained, but their respective properties are but imperfectly known. Oxide of lithium (lithia) differs from potash and soda in its power of saturating a greater quantity of any acid, and in forming difficultly soluble salts with the carbonic and phosphoric acids. It may be distinguished from the alkaline earths (lime and bary- tes) by the greater solubility of its saline compounds with the sulphuric and oxalic acids ; and by its acting in the state of car- bonate upon vegetable colours, like potash and soda. 393. Baryum. This metallic body may be obtained by nega- tively electrizing its oxide (which is the earth called barytes) in contact with mercury. An amalgam will thus be gradually formed, from which the mercury may be expelled by heat. The metal is of a dark gray colour, with a lustre inferior to that of cast- iron, and it is about twice as heavy as water. It speedily absorbs oxygen when exposed to air, crumbling into a white powder, which is the protoxide of baryum : and when thrown into water it suddenly decomposes that fluid, hydrogen being evolved, and the oxide which is formed dissolving in the water. The protox- ide of baryum (barytes) is not unfrequently found among minerals, in combination with either the carbonic or the sulphuric acid, with the latter of which jt constitutes the substance called pon- derous spar (terra ponderosa.) 394. Pure barytes has a caustic taste, turns vegetable blue co- lours green, and neutrallizes acids like the alkalies. It is very poisonous, as likewise are all the soluble salts formed of it. It is usually obtained in the state of a gray powder, the specific gravity of which is about 4. It is insoluble in pure alcohol, but very readily soluble in water, and it may be slaked like quick- lime, giving out a great quantity of heat during the process. Per- oxide of baryum may be produced by heating the protoxide in oxygen gas, which is rapidly absorbed, and a gray compound is formed. This substance is principally deserving of notice, as having been used by M. Thenard in the preparation of oxygenated water, of which some account has been already given. Baryum unites with chlorine, iodine, bromine, and fluorine, and also with some of the simple combustibles. How does lithia differ from the vegetable and marine alkalies ? How from lime and barytes ? How is baryum procured ? By what names do mineralogists distinguish the minerals formed of ba- ryum ? .What sensible and other properties belong to baryum? To what chemical purpose has the peroxide of baryum been applied ? N2 150 CHEMISTRY. 395. Calcium. This metal was discovered by Sir H. Davy, who procured it in a separate state from lime by the action of a Voltaic battery. It has, however, been obtained in very small quantities, and but little is known concerning- its physical proper- ties except that it has the colour and lustre of silver. When ex- posed to common air the metal takes fire, and burns with an in- tense white light, forming protoxide of calcium, or pure lime. The amalgam of calcium thrown into water is decomposed with the evolution of hydrogen, and the oxygen of the water unites with the calcium to form lime. The protoxide of calcium (lime) is a white pulverulent earth, which is one of the most abundant and most important of all natural substances. In the mineral king- dom it forms limestone and other rocks ; it is contained in many vegetable products, and also forms the basis of bone and other animal substances. It may be most readily obtained in the state of purity by exposing powdered calcareous spar, or white marble, to a strong red heat. 3.06. Pure lime, commonly called quicklime, has an acrid and alkaline taste, corrodes animal substances, and changes vegetable blue colours to green. It is very difficultly fusible, but facilitates extremely the fusion of other mineral bodies, as metallic ores, and it is therefore employed as a cheap and powerful flux. It is sparingly soluble in water, and hot water takes up a smaller quantity of it than cold, so that when lime-water is boiled, the lime is precipitated. Lime absorbs moisture from the air, and becomes converted into hydrate of lime, as also happens when it undergoes the process of slaking. Lime may be obtained in a crystalline state by placing lime-water under the exhausted re- coiverof an air-pump, together with sulphuric acid in another ves- sel, the water thus becoming slowly evaporated, imperfect hexa- gonal crystals will be formed, consisting of hydrate of lime. 397. Calcium is capable of entering into combination with oxy- gen in two proportions, forming, besides lime, a peroxide or deutoxide. The chloride of calcium, which is formed when pure lime is heated in chlorine, is known in commerce under the names of oxyrnuriate of lime and bleaching powder, extensively used for various purposes. 398. Strontium. This metal may be obtained from the earth called strontia, which is an oxide of strontium, by a process analogous to that described for the production of baryum. It possesses but a moderate degree of lustre, is difficult of fusion, and What effect results from the exposure of calcium to common air? How does that metal act upon water? How extensive is the protoxide of calcium found in nature ? How may it be obtained in a pure state ? What are its sensible properties ? For what purpose is it used In metallurgy? What remarkable effect has increase of temperature on water saturated with lime ? What use is made of the compound of lime with chlorine ? MAGNESIUM. 151 not volatile. It is converted into an oxide by exposure to atmos- pheric air, and it also decomposes water. The oxide of strontium, or strontia, derives its appellation from its having been found in a mineral, first discovered in a lead-mine at Strontian, in Argyll- shire, in which the earth is combined with carbonic acid. Strontia is a gray pulverulent mass, having decidedly alkaline properties. It may be slaked with water, giving out much heat, and forming a solid hydrate, which is readily soluble in boiling water, and deposits crystals on cooling. When immersed in alcohol, it causes the vapours of that fluid to burn with a bright red flame. Its taste is acrid ; but it differs from barytes in not being poisonous. Stron- tium unites with chlorine and some other bodies; but its com- pounds have been but slightly .examined. 399. Magnesium. Sir H. Davy was foiled in an attempt to procure magnesium by exposing the earth, in its pure state, to the action of the Voltaic battery ; but he succeeded better by galva- nizing solutions of the sulphate or nitrate of magnesia, in contact with mercury By this means a metallic solid was obtained, which sunk rapidly in water, though surrounded by globules of gas, producing magnesia; and it quickly changed in air, becoming covered with a white crust, or falling into a fine powder, which proved to be magnesia. The metal has since been obtained by M. Bussy from the action of potassium on chloride of magnesium, heated to redness in a porcelain tube. It appeared in the state of small brown scales, which, when rubbed in an agate mortar, left a metallic trace of a leaden colour. It burns, when strongly heated, with a red light, forming magnesia. 400. The oxide of magnesium, (magnesia,) in combination with acids, is abundantly distributed by nature in the mineral kingdom, entering into the composition of various rocks, and being found in considerable quantities in the water of the sea, and of mineral springs. It usually occurs in the state of sulphate, from which the carbonate is prepared, by the addition of carbonate of potash or of soda, when a precipitation takes place. The oxide of mag- nesium may be obtained pure by exposing carbonate of magnesia to a strong red heat, and the product, known by the name of calcined magnesia, is frequently used in medicine. It is a soft, white, infusible powder, having neither taste nor smell. It slightly reddens turmeric, and has some action on the blue tint of violets, turning it green, like alkalies. Magnesium combines with chlorine and iodine. Whence was strontium first procured? What are its properties ? What effect has this metal on alcohol ? \Vhat different methods have been employed to obtain the metal mag- nesium ? To what extent does the compound of magnesium and oxygen present itself in nature ? Under what name is that compound, when pure, generally known ? What alkaline property does it possess ? 1 52 CHEMISTRY. 401. Aluminum. This metal has been obtained in the state of a finely-divided, gray substance, or in small scales with some metallic lustre. It is very difficult of fusion ; and though in the pulverulent state it seems not to conduct electricity, it becomes a conductor when its particles are united. It does not become oxi- dized by mere exposure to the air; but if heated almost to red- ness, it burns, forming a white substance, having the general properties of aluminous earth. 402. The oxide of aluminum or alumine, is found in abundance in the mineral kingdom, constituting, either alone or with other substances, most of the precious stones, as the sapphire, the topaz, the ruby, and the garnet ; and it is a constituent part of the hardest and most ancient rocks, and in general also of the superior soil. In the state of clay it is largely used in making tobacco-pipes, bricks, pottery, and porcelain. In combination with sulphuric acid, this oxide forms alum, so extensively used in the arts and in medicine. Pure alumine may be obtained by precipitating a solu- tion of alum (sulphate of alumine) in water, by means of ammonia or carbonate of potash. A white, bulky hydrate of alumine will thus be obtained, which, when well washed and exposed to a white heat, will yield the earth in a state of purity. 403. Alumine is a white bland powder, which adheres to the tongue, but has neither taste nor smell, and does not affect vegeta- ble colours. It is insoluble in water, but when moistened with it, forms a d uctile, cohesive mass. It has a great affinity for moisture ; and after ignition, it will absorb from the atmosphere a quantity of water equal to half its weight. This earth enters into permanent combinations with various animal and vegetable colouring matters, and hence it is of great use in dying and calico-printing. Chloride of aluminum is a yellowish, transparent crystalline substance, which rises in vapour at 212. When exposed to the air it rapidly deliquesces, forming an acid solution. 404. Zirconium. This metal has been obtained from the earth called zircon (oxide of zirconium) by Galvanism, and also by heat- ing potassium with a peculiar salt, fluate of zirconia and potash carefully dried. It is thus procured in the state of a black powder, difficultly soluble in acids, except the hydrofluoric, which readily acts on it, extricating hydrogen. When rubbed between two hard substances, it appears in the form of shining scales, of a dark gray colour. If heated in atmospheric air, it burns brightly, form- ing zircon earth. This earth (oxide of zirconium) is a white What is the appearance of aluminum ? How is it affected by heat ? What is the chemical nature of the chief ingredient of most of the pre- cious stones ? For what purposes in the arts is alumine employed ? How may it be obtained in a pure state ? What distinguishing sensible properties does it possess ? What relation has pure alumine to water ? How is it employed in the arts ? How has zirconium been procured ? Enumerate its several properties. THORINUM. 153 insipid powder, which forms salts with different acids, and is sparingly dissolved by the carbonated alkalies ; but not by the alkalies in a pure state. 405. Glucinum. This metal may be obtained by decomposing its chloride by potassium. It is a gray substance, having but lit- tle metallic lustre, and very difficult of fusion. It is not affected by air or water at common temperatures ; but when heated, it burns, forming glucina, or oxide of glucinum. This oxide was first discovered in the beryl, and it also occurs in the emerald of Peru, and in the euclase ; but has not yet been found in any other minerals. It is a fine, white, soft powder, adhering to the tongue like pure clay. It does not affect vegetable colours, and is insolu- ble in water; with which, however, it forms a ductile paste. With the acids it combines to form salts, having a sweetish, astringent taste ; whence its name.* 406 Yttrium. This is the metallic basis of the earth called . yttria or ittria, which was discovered in a mineral found in the quarry of Ytterby in Sweden. This earth has since been met with only in one other mineral in the same country. Yttria (oxide of yttrium) is an insipid, white powder, which has no action on vegetable colours, and is remarkable for its specific gravity, which is 4.8. It is insoluble in water, and incapable of fusion, except at a very intense heat. With the acids it forms salts, having a sweetish, austere taste, but which have hitherto been but slightly examined. The metal has been procured, by decomposing the chloride of yttrium by means of potassium, in the state of iron- gray scales, which burn brilliantly when heated in oxygen gas or common air, forming yttria. The metal is not acted on by water, but dissolves in sulphuric acid. 407. Thorinum. Thorinum, or thorium, is the name given to a metal discovered by Berzelius. In 1816, in analysing some Swedish minerals, he obtained an earthy substance, which he concluded to be the oxide of a new metal, (thorium,) but he subsequently found it to be a subphosphate of yttria. However, in 1828, Berzelius received a black, heavy mineral, from the vicinity of Brevig, in Norway, which, on analysis, was found to consist chiefly of a silicate of a new earth, which constituted about 58 per cent, of the whole mineral. To the base of this earth he gave the name of thorium, because it resembled in its properties the subphosphate of yttria, to which the name had been previously applied. Thoria (oxide of thorium) displays considerable analo- gies with yttria, zirconia, and glucina. In what state was the oxide of glucinum first discovered ? What peculiar properties have its compounds with acids? Whence was yttria first procured ? By what means is its metallic base separated from composition? With what solvent will the metal combine ? To what substance was the name thorium first given ? To what has it been subsequently applied ? * From the Greek word TAvKv?, sweet. 154 CHEMISTRY. 408. Binary Combinations of the Metallic Elements of the Third Class with Oxygen and some other Non-metallic Elements. Iron. Black oxide of I., 1 Ir. 1 Ox. Red oxide of I., 2 Ir. 3 Ox. Chloride of I., 1 Ir. 1 Ch. Pefchloride of I., 2 Ir. 3 Ch. Sulphuret of I., 1 Ir. 1 S. Bisulphuret of I., 1 Ir. 2 S. Nickel. Oxide of N., 1 Nk. 1 Ox. Peroxide of N., 2 Nk., 3 Ox. Sulphuret of N., 1 Nk. 1 S. Zinc. White oxide of Z., 1 Zn. 1 Ox. Chloride of Z., 1 Zn. 1 Ch. Sulphuret of Z., (blende,) 1 Zn. 1 S. Cadmium. Oxide of C., 1 Cad. 1 Ox. Sulphuret of C., 1 Cad. 1 S. Cerium. Oxide of C., 1 Cer. 1 Ox. Peroxide of C., 2 Cer. 3 Ox. Lead. Protoxide of L., 1 Ld. 1 Ox. Red oxide of L., (minium,) 2 Ld. 3 Ox. Brown oxide of L., 1 Ld. 2 Ox. Chloride of L., 1 Ld. 1 Ch. Sulphuret of L., (galena,) 1 Ld. 1 S. Copper. Oxidule of C., 2 Cop. 1 Ox. Oxide of C., 1 Cop. 1 Ox. Deutoxide of C., 1 Cop. 2 Ox. Chloride of C. Perchloride of C. Hemisulphuret of C., 2 Cop. 1 S. Sulphuret of C., 1 Cop. 1 S. Enumerate the metallic elements of the third class. What are the binary compounds of iron? of nickel? of zinc? of cad mium ? of cerium ? of lead ? of copper ? METALLIC ELEMENTS. 155 Copper continued. Cop. 2 S. Cop. 5 S. Phosphuret of C., 1 Cop. 1 Ph. Bismuth. Oxide of B., 1 Bis. 1 Ox. Chloride of B., 1 Bis. 1 Ch. Sulphuret of B., 1 Bis. 1 S. Mercury. Black oxide of M., 1 Her. 1 Ox. Red oxide of M., 1 Mer. 2 Ox. Chloride of M., (calomel,) 1 Mer. 1 Ch. Perchloride of M. (corrosive sublimate,) 1 Mer. 2 Ch. Sulphuret of M., (Ethiops mineral,) 1 Mer. 1 S. Bisulphuret of M., (vermilion,) 1 Mer. 2 S. Silver. Oxide of S., 1 Sil. 1 Ox. Chloride of S., (luna corena, horn silver,) 1 Sil. 1 Ch. Sulphuret of S., 1 Sil. 1 S. Gold. Oxide of G., 1 Gd. 1 Ox. Peroxide of G., 1 Gd. 3 Ox. Chloride of G., 1 Gd. 1 Ch. Perchloride of G., 1 Gd. 3 Ch. Sulphuret of G., 1 Gd. 1 S. Persulphuret of G., 1 Gd. 3 S. Platina. Oxide of P., 1 PI. 1 Ox. Deutoxide of P., 1 PI. 2 Ox. Chloride of P., 1 PI. 1 Ch. Bichloride of P., 1 PI. 2 Ch. Palladium. Oxide of P., 1 Pal. 1 Ox. Sulphuret of P., 1 Pal. 1 S. How many persulphurets does copper form ? What are the binary compounds of bismuth? of mercury ? of silver ?- of gold ? With which of the non-metallic elements does platina combine ? With what ones does palladium unite ? 156 CHEMISTRY. Rhodium. Oxide of R., 1 Rh. 1 Ox. Peroxide of R., 2 Rh., 3 Ox. Iridium. Irid. 1 Ox. Oxide, of 1 Irid. 3 Ox. Osmium. ri os. i ox. 2 Os. 3 Ox. Oxides of O.J 1 Os. 2 Ox. 1 Os. 3 Ox. .1 Os. 4 Ox. 409. Iron. But few of the elementary bodies with which we are acquainted occur so abundantly and in so many various forms as iron. Among the metals, excepting some of the bases of earths and alkalies, there is not one which enters so largely into the com- position of mineral, vegetable, and animal substances. It is also distinguished for its general utilty, possessing admirable pro- perties, adapting it for the construction of a multiplicity of weapons and instruments, useful in peace and war, in arts, manufactures, and for domestic purposes. Its capabilities were known, and, to a certain extent, duly appreciated by the ancients ; but they have been, in modern times, far more fully developed, and the metal and its compounds consequently rendered subservient in a most extraordinary degree to the luxuries as well as the wants of our contemporaries. Chain-bridges, steam-engines, watch-springs, and magnets, are among the numerous articles constructed of this metal, the invention of which is comparatively of modern date. 410. Though iron, when pure, requires, to melt it, an extremely high temperature, it is susceptible of an imperfect kind of fusion at a white heat; for when exposed to that heat, it becomes so much softened, especially at the surface, that if two pieces are placed in contact, and hammered, they may be most firmly and securely united. This operation is termed welding, and the tem- iture at which it is effected, is sometimes called a welding 411. The combustibility of iron has been already noticed.* With which of the non-metallic elements does rhodium combine? iri- dium ? osmium ? Which of the metals is the most widely diffused ? Into what classes of natural productions does iron enter ? How early did mankind employ it for useful purposes ? To what purpose is the semi-fluid state of iron applied ? What is meant by welding ? * See Nos. 171, 172. NICKEL ZINC CADMIUM. 157 When it is burnt, either in oxygen gas or atmospheric air, the protoxide of iron is formed ; if this compound be exposed to a red heat for some hours, it combines with an additional quantity of oxygen, and becomes converted into the peroxide. Both the oxides combine with water, constituting hydrated oxides of iron. Chloride of iron is a brittle, lameller substance, of a gray colour, which requires for its fusion a red heat. Perchlcride of iron is the product of the combustion of iron wire in chlorine gas. The metal burns with a red light, forming a compound which sublimes in iridescent brown scales. The bisulphurut of iron is a native mineral, occurring in the state of gold-coloured crystals, called pyrites. Iron combines in variable proportions with carbon : when the metal is in excess, composing the different kinds of steel and cast-iron ; and when the carbon largely exceeds, form- ing plumbago. 412. Nickel. This is a hard metal, of a white colour, malleable and ductile, but difficult of fusion, and not acted on by atmospheric air or water at common temperatures. When pure it may be rendered magnetic, like iron ; and it has heretofore been sometimes employed in the construction of magnetic needles. If exposed to intense heat with access of air, it becomes slowly oxidized ; and it burns with vivid scintillations in oxygen gas. 413. Zinc, This metal in appearance resembles lead, but is, when untarnished, of a lighter colour. It speedily attracts oxygen when exposed to air and moisture; and it is easily dissolved by acids and alkalies, -both in the metallic state and when oxidated. It is malleable and ductile when heated to between 210 and 300 Fahrenheit. At about 725* it melts, and becomes cyrstallized on cooling. If exposed to a temperature beyond its melting-point, with the access of air, it burns with a bright, bluish flame, form- ing the oxide, formerly called flowers of zinc. 414. Cadmium resembles tin in its sensible properties; and when heated in atmospheric air forms a sublimate, which condenses into a brownish-yellow oxide. The oxides of this as well as the three preceding metals, are readily reduced by heat alone to the metallic state. 415. Cerium. The protoxide of cerium is a white powder, which differs from the oxides of the metals just described, in being What two compounds does it form with oxygen ? v What is the appearance of chloride of iron? To what is the term pyrites applied ? What are the chief properties of nickel ? What property has it in common with iron? Between what temperatures is zinc malleable ? About what temperatures is that metal said to melt ? To which of the other metals is cadmium most nearly allied ? By what means are the oxides of iron, nickel, zinc, and cadmium re- duced to the metallic state? * 658 according to Daniell. o 158 CHEMISTRY. extremely difficult of reduction. The metal itself is but imperfectly known. 416. Lead. This is well known to be a heavy, soft, and readily fusible metal, which, though malleable and ductile, is deficient in tenacity. It soon becomes oxidized when exposed to a moist at- mosphere. When heated by means of an oxyhydrogen blowpipe, it burns with a bluish flame. If melted and kept stirred, so as to promote the free access of air, it becomes converted into the pro- toxide, a yellow powder, used as a pigment under the name of massicot; and in a semi-vitrified state it constitutes litharge. The brown oxide of lead exhibits the phenomenon of spontaneous com- bustion, when it is triturated with sulphur. Lead in a finely- divided state, if thrown into chlorine gas moderately warmed, burns with a white flame, and throws off sparks. The product of this operation is chloride of lead, which may also be obtained by decomposing the solution of lead in nitric acid, by means of chlo- ride of sodium, (common salt.) It fuses at a heat below redness, and when cooled again, has the appearance of a horny substance, whence it was formerly named horn lead, (plumbum curneum.) 417. Copper. This metal being used for many domestic purposes, its physical properties are generally known. It is malleable and ductile beyond most other metals, except gold, silver, platina, and iron ; and hence it forms fine wire, and may be beaten into thin leaves. It burns brilliantly when heated in the combined flame of oxygen and hydrogen, giving out a dazzling green light. If ex- posed to air and moisture, it tarnishes, combining with oxygen to form a bluish-green rust, (serugo.} The deutoxide or peroxide of copper is an insipid, black powder. Leaves or filings of copper take fire, and burn spontaneously in chlorine gas, forming the chloride of copper, a yellowish, slightly transparent substance, easily fusible, which has been called resin of copper. If sulphur and filings of copper be heated together, a sudden and brilliant combustion takes place, even when the process is conducted in a vacuum.* 418. Bismuth. This is a light reddish-coloured metal, of a lamellar structure, moderately hard, and destitute of malleability. It becomes tarnished by exposure to air ; but is not affected by water. Its fusibility has been already noticed. If strongly heated in the air, it burns with a blue flame, forming a yellowish oxide, which has been called flowers of bismuth. This substance, like the oxide of lead, is fusible and verifiable. Finely-divided bismuth becomes inflamed when gently heated in chlorine gas, forming a gray, granular compound. What are the chemical properties of lead ? What is the colour of the flame of copper in oxygen ? What effect has chlorine on copper ? What takes place when copper in fine particles is heated with sulphur ? What are the colour and crystalline form of bismuth ? 3y what means may the combustion of bismutli be effected ? See No. 70. MERCURY SILVER GOLD. 159 419. Mercury. This metal is distinguished by its extraordinary fusibility, so that it requires a temperature 39 below zero, Fahren- heit, to congeal or render it solid. It is in that state malleable and ductile, though not to any great extent. It is extremely volatile, subliming- in some degree at low temperatures ; and at about 660 it boils rapidly, and may thus be purified by distillation, like water. When, heated a little beyond the boiling point, it becomes oxidated ; and if the oxide be exposed to a considerably higher temperature, the oxygen is driven off, and the metal revived.* 420. The chlorides of mercury are among the most important preparations of this metal used in medicine. The first, commonly called calomel, may be formed by exposing the metal to chlorine gas at common temperatures ; but the usual mode of obtaining this compound is by decomposing the solution of mercury in nitric acid, by means of muriatic acid or chloride of sodium, (common salt.) The product is a ponderous white powder, which, when exposed to heat, sublimes unaltered. The perchloride of mercury is a crystalline substance, which may be procured by heating the metal in chlorine gas ; but it is prepared for use by boiling together sulphate of mercury and common salt. It is well known as a powerful poison, under the name of corrosive sublimate. The bi- sulphuret of mercury, which occurs as a native mineral, under the name of cinnabar, and the same substance artificially produced, af- fords a fine scarlet colour for painting. 421. Silver. This metal requires a great heat to melt it ; but by a fierce and long continued fire it may be volatilized. It does not tarnish in the air from absorption of oxygen ; but, when sulphurous vapours are present, its surface becomes tinged with purple from the formation of sulphuret of silver ; and the same effect is produced when a silver spoon is dipped in the yolk of an egg, which con- tains sulphur. The oxide of silver may be formed by exposing the metal to intense heat, with the access of air ; but it is more readily obtained by decomposing the nitrate of silver with lime water, when it constitutes a tasteless olive-coloured powder, insoluble in water. Chloride of silver has the same horny appearance as chlo- ride of lead; and it is therefore called horn silver, (luna cornea.} 422. Gold. The most powerful heat of our furnaces has no ef- fect on this metal beyond that of fusing it ; but it may be made to undergo combustion, and form a purple oxide, by heating it with the flame of an oxy hydrogen blowpipe, or by means of electricity What remarkable property distinguishes mercury from all other metals ? What class of the compounds of this metal are used in medicine ? What is the form of corrosive sublimate and what is the common process of procuring it ? To what purpose is the bisulphuret of mercury applied ? What chemical properties of silver can you enumerate? What causes the colour given to a silver spoon by dipping it in the yolk of an egg ? How may gold be oxidized ? * See No. 82. 160 CHEMISTRY. It may also be oxidated indirectly by solution in the nitro-muriatic acid, (aqua regie,} and precipitation by caustic potash or magnesia. If the peroxide of gold be dissolved in muriatic acid, and ammonia be employed to precipitate it, a detonating powder (Jlurum Ful- minans) will be obtained, which explodes when rubbed or heated 423. Platina. This metal in a state of purity is the heaviest body hitherto discovered, having nearly 22 times the specific gra- vity of water. It is so difficult of fusion, that it can only be pre- pared for use by a complicated process. But, like iron, it may be welded by hammering the metal when intensely heated ; and thus vessels and other utensils may be formed, highly valuable for the purposes of art, on account of their relative indestructibility. Pla- tina may be oxidated by treating it with nitro-muriatic acid and alkali, as in the case of gold, or by heating it with nitre, and likewise by the influence of electricity. 424. Palladium, lihodium, In'dium, and Osmium are metals which have been found in comparatively small quantities, mixed with crude platina, in the state in which it appears in commerce. Palladium forms a hard, durable alloy with gold, which has been used in the construction of mathematical instruments : and rhodium has been employed for pointing the nibs of pens. Iridium and os- mium do not appear to have been applied to any useful purpose; nor do the compounds of either of these four metals require to be further noticed. 425. Such is an outline of the character and composition of the various simple ingredients of which the material world around us is composed. It can hardly be expected that we should, in a treatise like this, enter into an elaborate statement of all the various forms which they present when combined. It will, be- sides, be in course to state, when treating of mining, of the methods of ascertaining the chemical nature of ores and, under the head of mineralogy, we shall give some brief views of the general con- stituents of mineral substances. But it will be proper here to exhibit an application of the principles of chemistry to certain other important subjects of which this science is justly regarded as an indispensable groundwork. These are the chemical com- binations found in the vegetable and animal kingdoms, considered as separate departments of natural history, the nature of soils and the character of mineral w r aters. Previously to the consideration of these topics, it will be proper for us to explain some of the methods of analysis. Analysis. 426. This word is applied by chemists to denote that se- ries of operations by which the component parts of bodies are How is fulminating gold procured ? What is the relative weight of platina compared with other metals ? What mechanical processes may be performed on platina at a high tem- perature ? How may it be combined with oxygen ? What use has been made of the metal palladium ? ANALYSIS OF EARTHS AND STONES. 161 determined, whether they be merely separated, or exhibited apart from each other ; or whether these distinctive properties be exhi- bited by causing them to enter into new combinations. Analysis of Earths and Stones. 427. The first step in the examination of indurated earths or stones, is somewhat different from that of such as are pulverulent. Their specific gravity should first be examined ; also their hard- ness, whether they will strike fire with steel or can be scratched by the nail, or only by crystal, or stones of still greater hardness ; also their texture, perviousness to light, and whether they be manifestly homogeneous or compound species, &c. 428. (2cf.) In some cases we should try whether they imbibe water, or whether water can extract any thing from them by ebul- lition or digestion. (3c?.) Whether they be soluble in, or effervesce with acids, be- fore or after pulverization ; or whether decomposable by boiling in a strong solution of potash, &c. as gypsums and ponderous spars are. (4/A.) Whether they detonate with nitre. (5M.) Whether they yield the fluoric acid by distillation with sulphuric acid or ammonia, by distilling them with potash. (6//J.) Whether they be fusible per se with a blowpipe, and how they are affected by soda, borax, and microcosmic salt ; and whether they decrepitate when gradually heated. (7A.) Stones that melt per se with the blowpipe are certainly compound, and contain at least three species of earth, of which the calcareous is probably one; and if they give fire with steel, the sileceous is probably another. 429. Of the primary earths, only four are usually met with in minerals, viz. silica, alumina, magnesia, and lime, associated with some metallic oxides, which are commonly iron, manganese, nickel, copper, and chromium. 430. If neither acid qgp- alkali be expected to be present, the mineral is mixed in a silver crucible, with thrice its weight of pure potash and a little water. Heat is gradually applied to the covered crucible, and is finally raised to redness ; at which tem- perature it ought to be maintained for an hour. If the mass, on inspection, be a perfect glass, silica may be regarded as the chief constituent of the stone ; but if the vitrification be very imperfect, and the bulk much increased, alumina may be supposed to predo- minate. A brownish or dull green colour indicates the presence of iron; a bright grass-green, which is imparted to water, that of How is the term analysis applied by chemists ? What is the first step in the examination of stones or earths ? What are the several processes after the gravity and hardness oi a mi- neral have been ascertained. How many of the primary earths usually occur in minerals ? In what manner are minerals destitute of acids and alkalies to be treated ? How is the presence of silica indicated in the course of an analysis ? 2 163 CHEMISTRY. manganese ; and from a greenish-yellow, chromium may be ex- pected. The crucible, still a little hot, being first wiped, is put into a capsule of porcelain or platinum ; when warm distilled water is poured upon the alkaline earthy mass, to detach it from the crucible. Having transferred the whole of it into the capsule, muriatic acid is poured on, and a gentle heat applied, if necessary, to accomplish its solution. If the liquid be of an orange-red colour, we infer the presence of iron ; if of a golden-yellow, that of chromium ; and if of a purplish-red, that of manganese. 431. The solution is next to be evaporated to dryness on a sand bath, or over a lamp, taking care so to regulate the heat that no particles be thrown out. Towards the end of the evaporation, it assumes a gelatinous consistence. At this period it must be stirred frequently with a platinum spatula or glass rod, to promote the disengagement of the muriatic acid gas. After this, the heat may be raised to fully 212 F. for a few minutes. 432. Hot water is now to be poured on in considerable abun- dance, which dissolves every thing except the silica. By filtra- tion, this earth is separated from the liquid ; and being washed with hot water, it is then dried, ignited, and weighed. It consti- tutes a fine white powder, insoluble in acids, and feeling gritty between the teeth. If it be coloured, a little dilute muriatic acid must be digested on it, to remove the adhering metallic particles, which must be added to the first solution. This must now be re- duced by evaporation to the bulk of half a pint. Carbonate of potash being then added till it indicates alkaline excess, the liquid must be made to boil for a little. A copious precipitation of the earth and oxide is thus produced. The whole is thrown on a filter, and after it is so drained as to assume a semi-solid consist- ence, it is removed by a platinum blade, and boiled in a capsule for some time, with solution of pure potash. Alumina and glu- cina are thus dissolved, while the other earths and the metallic oxides remain. 433. This alkalino-earthy solution, separated from the rest by filtration, is to be treated with an excels of muriatic acid ; after which carbonate of ammonia being added also in excess, the alumina is thrown down, while the glucina continues dissolved. The first earth separated by filtration, washed, dried, and ignited, gives the quantity of alumina. The nature of this may be further demonstrated, by treating it with dilute sulphuric acid and sul- phate of potash, both in equivalent quantities, when the whole will be converted into alum. The filtered liquid will deposit its glucina, on dissipating the ammonia by ebullition. It is to be separated by filtration, to be washed, ignited, and weighed. 434. The mingled metallic oxides must be digested with abun- dance of nitric acid, to acidify the chromium. The liquid is next treated with potash, which forms a soluble chromate, while it How is the presence of iron inferred ? How are earthy materials separated from the solution of a mineral ? ANALYSIS OF EARTHS AND STOXES. 163 lickel is separated from the iron, by treating- their solution in nuriatic acid with water of ammonia. The latter oxide, which throws down the iron and nickel. The chromic acid may be se- parated from the potash by muriatic acid and digestion with heat, washed, dried till it becomes a green oxide, and weighed. The nickel muriatic falls, may he separated by the filter, dried, and weighed. By evaporating the liquid, and exposing the dry residue to a moderate heat, the ammoniacal salt will sublime, and leave the oxide of nickel behind. The whole separate weights must now be col- lected in one amount, and if they constitute a sum within two per cent, of the primitive weight, the analysis may be regarded as giving a satisfactory account of the composition of the mineral. But if the deficiency be considerable, then some volatile ingre- dient, or some alkali or alkaline salt, may be suspected. 435. A portion of the mineral, broken into small fragments, is to be ignited in a porcelain retort, to which a refrigerated re- ceiver is fitted. The water, or other volatile or condensable mat- ter, if any be present, will thus be obtained. But if no loss of weight be sustained by ignition, alkali, or a volatile acid, may be looked for. The latter is usually the fluoric. It may be expelled by digestion with sulphuric acid. It is exactly characterized by its property of corroding glass. 436. Beside this general method, some others may be used in particular cases. Thus, to discover a small proportion of alumina or magnesia in a solution of a large quantity of lime, pure ammo- nia may be applied, which will precipitate the alumina or magne- sia, (if any there be.) but not the lime. Distilled vinegar applied to the precipitate will discover whether it be alumina or magnesia. 437. (Zdly.} A minute portion of lime or baryta, in a solution of alumina or magnesia, may be discovered by the sulphuric acid, which precipitates the lime and baryta : the solution should be dilute, else the alumina also would be precipitated. If there be not an excess of acid, the oxalic acid is still a nicer test of lime. 438. (3c?/y.) A minute proportion of alumina in a large quantity of magnesia may be discovered, either by precipitating the whole and treating it with distilled vinegar ; or by heating the solution nearly to ebullition, and adding more carbonate of magnesia until the solution is perfectly neutral, which it never is when alumina is contained in it, as this requires an excess of acid to keep it in solution. 439. (4M/y.) A minute portion of magnesia in a large quan- tity of alumina, is best separated by precipitating the whole, and treating the precipitate with distilled vinegar. How are nickel and iron separated ? How is the presence of fluoric acid detected in the course of an analysis? What test detects the presence of alumina or magnesia in a large quan- tity of lime ? How is a small proportion of alumina known to exist in a large quan- tity of magnesia ? 164 CHEMISTRY. 440. (Lastly.} Lime and baryta are separated by precipitating both with the sulphuric acid, and evaporating the solution to a small compass, pouring off the liquor, and treating the dried precipitate with 500 times its weight of boiling water : what remains undis- solved is sulphate of baryta. 441. Sir H. Davy observes, that boracic acid is very useful in analyzing stones that contain a fixed alkali ; as its attraction for the different earths at the heat of ignition is considerable, and the compounds it forms with them are easily decomposed by the mineral acids dissolved in water. ^ Lately, carbonate or nitrate of baryta, and carbonate with nitrate of lead have been introduced into mineral analysis with great advantage, for the fluxing of stones that may contain alkaline matter. Vegetable Kingdom. 442. The principles of which vegetables are composed, if we pursue their analysis as far as our means have hitherto allowed, are chiefly carbon, hydrogen and oxygen. Nitrogen is a consti- tuent principle of several, but for the most part in small quantity. Potash, soda, lime, magnesia, silex, alumina, sulphur, phospho- rus, iron, manganese, and muriatic acid have likewise been reckoned in the number; but some of these occur only occasionally, and chiefly in very small quantities ; and are scarcely more enti- tled to be considered as belonging to them than gold, or some other substances that have been occasionally procured from their decomposition. 443. The following are the principal products of vegetation : (1.) Sugar. Crystallizes; soluble in water and alcohol; taste sweet ; soluble in nitric acid, and yields oxalic acid. (2.) Sarcocoll. Does not crystallize ; soluble in water and alcohol; taste bitter sweet; soluble in nitric acid, and yields oxalic acid. (3.) Jisparagin. Crystallizes ; taste cooling and nauseous ; soluble in hot water; insoluble in alcohol ; soluble in nitric acid, and converted into bitter principle and artificial tannin. 444. (4.) Gum. Does not crystallize; taste insipid ; soluble in water, and forms mucilage; insoluble in alcohol; precipitated by silicated potash ; soluble in nitric acid, and forms mucous and oxalic acids. (5.) Ulmin. Does not crystallize ; taste insipid ; soluble in How are lime and baryta separated ? For what purpose is boracic acid useful in analysis ? For what analyses are carbonates and nitrates of baryta and lead useful ? What are the simple substances chiefly employed in the composition of vegetables ? What earthy and metallic ingredients are occasionally met with in ve- getable substances ? What are the properties of sugar, sarcocoll, and asparagin ? What common properties have gum and ulmin ? VEGETABLE KINGDOM. 165 water, and does not form mucilage ; precipitated by nitric and hydrochloric acid in the state of resin ; insoluble in alcohol. (G.) Inulin. Awhile powder; insoluble in cold water ; solu- ble in boiling water; but precipitates unaltered after the solution cools ; insoluble in alcohol ; soluble" in nitric acid, and yields oxalic acid. 445. (7.) Starch. A white powder ; taste insipid ; insoluble in cold water; soluble in hot water; opaque and glutinous; pre- cipitated by an infusion of nut-galls ; precipitate re-dissolved by a heat of 120 ; insoluble in alcohol ; soluble in dilute nitric acid, and precipitated by alcohol ; with nitric acid yields oxalic acid and a waxy matter. (8.) Indigo. A blue powder, taste insipid ; insoluble in water, alcohol, ether ; soluble in sulphuric acid; soluble in nitric acid, and converted into bitter principle and artificial tannin. (9.) Gluten. Forms a ductile elastic mass with water; par- tially soluble in water; precipitated by infusion of nut-galls and oxygenized muriatic acid ; soluble in acetic acid and muriatic acid ; insoluble in alcohol ; by fermentation becomes viscid and adhesive, and then assumes the properties of cheese; soluble in nitric acid, and yields oxalic acid. 446. (10.) Albumen. Soluble in cold water; coagulated by heat, and becomes insoluble ; insoluble in alcohol ; precipitated by infusion of nut-galls ; soluble in nitric acid ; soon putrefies. (11.) Fibrin. Tasteless; insoluble in water and alcohol; so- luble in diluted alkalies, and in nitric acid ; soon putrefies. (12.) Gelatin. Insipid; soluble in water ; does not coagulate when heated ; precipitated by infusion of galls. (13.) Bitter principle. Colour yellow or brown ; taste bitter; equally soluble in water and alcohol ; soluble in nitric acid ; pre- cipitated by nitrate of silver. 447. (14.) Extractive. Soluble in water and alcohol ; insoluble in ether; precipitated by oxygenized muriatic acid, muriate of tin, and muriate of alumina ; but not by gelatin ; dyes fawn colour. (15.) Tannin. Taste astringent; soluble in water and in alco- hol of sp. grav. 0.810 ; precipitated by gelatin, muriate of alumina, and muriate of tin. (16.) Fixed oils. No smell ; insoluble in water and alcohol ; form soaps with alkalies ; coagulated by earthy and metallic salts. (17.) Wax. Insoluble in water; soluble in alcohol, ether, and oilsj forms soap with alkalies ; fusible. 448. (18.) Volatile oil. Strong smell; insoluble in water; soluble in alcohol ; liquid ; volatile ; oily ; by nitric acid inflamed, and converted into resinous substances. What difference of properties exists between inulin and starch? What are the peculiar properties of indigo? What are the distinctive characters of gluten ? How are albumen, fibrin, and gelatin distinguished ? Give the respective distinctive characters of bitter principle, extractive, and tannin. What are the marked differences between fixed oils, wax, and volatile oils ? 1G6 CHEMISTRY. (19.) Camphor. Strong odour; crystallizes; very little soluble in water ; soluble in alcohol, oils, acids; insoluble in alkalies; burns with a clear flame, and volatilizes before melting 1 . (20.) Birdlime. Viscid; taste insipid; insoluble in water; partially soluble in alcohol ;~very soluble in ether; solution green. 449. (21.) Resins. Solid; melt when heated; insoluble in water; soluble in alcohol, ether, and alkalies; soluble in acetic acid ; by nitric acid converted into artificial tannin. (22.) Guaiacum. Possesses the characters of resins ; but dis- solves in nitric acid, and yields oxalic acid and no tannin. (23.) Balsams. Possess the characters of the resins, but have a strong 1 smell ; when heated, benzoic acid sublimes ; it sublimes also wfien they are dissolved in sulphuric acid ; by nitric acid converted into artificial tannin. 450. (24.) Caoutchouc. Very elastic ; insoluble in water and alcohol ; when steeped in ether, reduced to a pulp, which ad- heres to every thing ; fusible, and remains liquid ; very combus- tible. (25.) Gum resins. Form milky solutions with water, transpa- rent with alcohol ; soluble in alkalies ; with nitric acid converted into tannin ; strong smell ; brittle, opaque, infusible. (26.) Cotton. Composed of fibres; tasteless; very combusti- ble ; insoluble in water, alcohol, and ether ; soluble in alkalies; yields oxalic acid and nitric acid. 451. (27.) Suber. Burns bright and swells; converted by nitric acid into suberic acid and wax ; partially soluble in water and alcohol. (28.) Wood. Composed of fibres, tasteless; insoluble in water and alcohol; soluble in weak alkaline lixivium; precipitated by acids; leaves much charcoal when distilled in a red heat; soluble in nitric acid, and yields oxalic acid. 452. To the preceding we may add, emetin, fungin, hematin, nicotin, pollenin, solanine, caffein, narcotine; the new vegetable alkalies, aconita, atropia, brucia, cinchonia, cicuta, datura, delphia, hyosciama, morphia, picrotoxia, quinia, corydalia, guarania, stron- tia, veratria ; and various vegetable acids. MM. Dumas and Pelletier have published a memoir on the ele- mentary composition and certain characteristic properties of the organic salifiable bases (vegeto-alkalies.) The following is a tabular view of the relations of carbon and azote in these alkaline bodies. What are the distinctive characters of camphor? bird-lime ? What similarities and what differences are remarked between resins and balsams ? How are gum resins characterized ? In what substances is cotton soluble? What product does it yield when tested with nitric acid? In what substances is suber soluble ? in what is wood soluble ? ANALYSIS OF VEGETABLES. 167 Carbonic acid. Azote. Quinia, 100 . 5.1 Cinchonia, 100 . 5.0 Strychnia, 100 . 4.9 Narcotine, 100 . 4.5 Brucina, 100 . 5.0 Morphia, 100 . 3.2 Veratria, 100 . 3.2 Emetin, 100 . 3.1 Caffein, 100 . 20.0 Analysis of Vegetables. /', 453. The analysis of vegetables requires various manipulations and peculiar attention, as their principles are extremely liable to be altered by the processes to which they are subjected. It was long before this analysis was brought to any degree of perfection. 454. Some of the immediate materials of vegetables are sepa- rated to our hands by nature in a state of greater or less purity ; as the gums, resins, and balsams, that exude from plants. The expressed juices contain various matters that may be separated by the appropriate reagents. Maceration, infusion, and decoction in water, take up certain parts soluble in this menstruum ; and alcohol will extract others that water will not dissolve. 455. As the ultimate constituents of all vegetable substances are carbon, hydrogen, and oxygen, with occasionally azote, the problem of their final analysis resolves into a method of ascer- taining the proportion of these elementary bodies. MM. Gay Lussac and Thenard contrived a very elegant apparatus for vege- table and animal analysis, in which the matter in a dried state was mixed with chlorate of potash, and formed into minute pellets. These pellets being projected through the intervention of a stop- cock of peculiar structure into an ignited glass tube, were instantly resolved into carbonic acid and water. The former product was received over mercury, and estimated by its condensation with potash ; the latter was intercepted by ignited muriate of lime, and was measured by the increase of weight which it communicates to this substance. By previous trials, the quantity of oxygen which a given weight of the chlorate of potash yielded by igni- tion was known ; and hence the carbon, hydrogen, and oxygen, derived from the organic substance, as well as the residual azote of the gaseous products were determined. . 456. M. Berzelius modified the above apparatus, and employed the organic products in combination with a base, generally oxide of lead. He mixed a certain weight of this neutral compound with a known quantity of pure chlorate of potash, and triturated the whole with a large quantity of muriate of soda, for the pur- What proportions have the vegeto-alkalies been found to contain of carbonic acid and azote ? What circumstance renders vegetable analysis more difficult than that of minerals ? What is the great question to be solved in the analysis of vegetables ? How did Gay Lussac and Thenard execute their analyses ? 1 68 CHEMISTRY. pose of moderating the subsequent combustion. This mingled dry powder is put into a glass tube about half an inch in diameter, and eight or ten inches long, which is partially enclosed in a fold of tin-plate, hooped with iron wire. One end of the tube is her- metically sealed beforehand, the other is now drawn to a pretty fine point by the blowpipe. This termination is inserted into a glass globe about an inch in diameter, which joins it to a long tube containing dry muriate of lime in its middle, and dipping at its other extremity into the mercury of a pneumatic trough. The first tube, with its protecting tin case, being exposed gradually to ig- nition, the enclosed materials are resolved into carbonic acid, water, and azote, which come over, and are estimated as above described. 457. M. Gay Lussac has more recently employed peroxide of copper to mix with the organic substance to be analyzed ; because, while it yields its oxygen to hydrogen and carbon, it is not acted on by azote ; and thus the errors resulting from the formation of nitric acid with the chlorate of potash are avoided. Berzelius has afforded satisfactory evidence by his analyses, that the simple apparatus which he employed is adequate to every purpose of chemical research.* Animal Kingdom. 458. Animal bodies may be considered as peculiar apparatus for carrying on a determinate series of chemical operations. Ve- getables seem capable of operating with fluids only, and at the temperature of the atmosphere. But most animals have a provi- sion for mechanically dividing solids by mastication, which an- swers the same purpose as grinding, pounding, or levigation does in our experiments ; that is to say, it enlarges the quantity of sur- face to be acted upon by solvents. 459. The process carried on in the stomach appears to be of the same kind as that which we distinguish by the name of digestion ; What method did Berzelius employ to obtain and estimate the compo- nents of vegetable matter ? In what light may animal bodies be considered ? * Perhaps one of the most curious substances of a vegetable character that has hitherto been analyzed, is the inflammable snow which fellon the llth of April, 1832, not far from VVolokalamsk, and covered a consider- able extent of ground to the depth of one or two inches. This substance was of a yellowish tint, transparent, soft, and elastic; insipid, but having the odour of rancid oil. Its sp. grav. was 1.1. It melted when heated in a close vessel, and yielded, by distillation, the usual products of vegetable substances, leaving a b'rilliant charcoal. It burned with a blue flame, without smoke ; was insoluble in cold water, but melted and floated on the surface of boiling water; was dissolved by boiling alcohol, and in car- bonate of soda, and acids, and threw down from this latter solution a yel- low viscid substance, soluble in cold alcohol, and ^which contained a pe- culiar acid. The analysis by means of the oxide of copper, gave from this substance Carbon, 0.615. ) Hydrogen, 0.070. V 1.000. Oxygen, 0.315.) Oxygt M. Herman, who analyzed this substance, gave it the name of oil of heaven. This material is supposed to be the pollen of pine or fir trees. ED ANIMAL KINGDOM. 169 and the bowels, whatever other uses they may serve, evidently form an apparatus for filtering or conveying off the fluids ; while the more solid parts of the aliments, which are probably of such a nature as not to be rendered fluid, but by an alteration which would perhaps destroy the texture of the machine itself, are re- jected as useless. 460. When this filtered fluid passes into the circulatory vessels, through which it is driven with considerable velocity by the me- chanical action of the heart, it is subjected not only to all those changes which the chemical action of its parts is capable of pro- ducing, but is likewise exposed to the air of the atmosphere in the lungs, into which that elastic fluid is admitted by the act of respiration. Here it undergoes a change of the same nature as happens to other combustible bodies, when they combine with its vital part, or oxygen. This vital part becomes condensed, and combines with the blood, at the same time that it gives out a large quantity of heat, in consequence of its own capacity for heat being diminished. A small portion of azote likewise is absorbed, and carbonic acid is given out. 461. Some curious experiments of Spallanzani show, that the lungs are not the sole organs by which these changes are effected. Worms, insects, shells of land and sea animals, egg shells, fishes, dead animals, and parts of animals, even after they have become putrid, are capable of absorbing oxygen from the air, and giving out carbonic acid. They deprive atmospheric air of its oxygen as completely as phosphorus. Shells, however, lose this property when their organization is destroyed by age. Amphibia, deprived of their lungs, lived much longer in the open air, than others in air destitute of oxygen. It is remarkable, that a larva, weighing a few grains, would consume almost as much oxygen in a given time, as one of the amphibia a thousand times its bulk. 462. The following are the peculiar chemical products of ani- mal organization : Gelatin, albumen, fibrin, fat, caseous matter, colouring matter of blood, mucus, urea, picromel, osmazome, sugar of milk, and sugar of diabetes. The compound animal products are the various solids and fluids, whether healthy or moroid, that are found in the animal body ; such as muscle, skin, bone, blood, urine, bile, morbid concretions, brain, &c. 463. When animal substances are left exposed to the air, or immersed in water or other fluids, they surfer a spontaneous change, which is more or less rapid according to circumstances. The spontaneous change of organized bodies is distinguished by the name of fermentation. In vegetable bodies there are distinct stages or periods of this process, which have been divided into What chemical office does the stomach of animals perform? Into what vessels do the liquids JUtered by the alimentary canals next pass ? What curious facts has Spallanzani observed in regard to the respiration of animals? What are the products of the processes performed by the or- gans of animals ? How is the decomposition of animal substances naturally effected? 170 CHEMISTRY. the vinous, acetous, and putrefactive fermentations. Animal sub- stances are susceptible only of the two latter, during which, as in all other spontaneous changes, the combinations of chemical principles become in general more and more simple. There is no doubt but much instruction might be obtained from accurate ob- servations of the putrefactive processes in all their several varie- ties and situations ; but the loathsomeness and danger attending on such inquiries have hitherto greatly retarded our progress in this department of chemical science. Soils. 464. The soil or earth in which vegetables grow varies con- siderably in its composition, or in the proportions of the different earths of which it consists ; and some plants are found to thrive best in one kind of soil, others in another. 465. In cases where a barren soil is examined with a view to its improvement, it ought in all cases, if possible, to be compared with an extremely fertile soil in the same neighbourhood, and in a similar situation : the difference given by their analyses would indicate the methods of cultivation, and thus the plan of improve- ment would be founded upon accurate scientific principles. 466. If the fertile soil contained a large quantity of sand, in proportion to the barren soil, the process of melioration would depend simply upon a supply of this substance ; and the method would be equally simple with regard to soils deficient in clay or calcareous matter. 467. In the application of clay, sand, loam, marl, or chalk, to lands, there are no particular chemical principles to be observed ; but when quicklime is used, great care must be taken, that it is not obtained from the magnesian limestone; for in this case, as has been shown by Mr. Tennant, it is exceedingly injurious to land. The magnesian limestone may be distinguished from the common limestone by its greater hardness, and by the length of time that it requires for its solution in acids ; and it may be analyzed by the process for carbonate of lime and magnesia. 468. When the analytical comparison indicates an excess of vegetable matter as the cause of sterility, it may be destroyed by much pulverization and exposure to air, by paring and burning, or the agency of lately-made quicklime. And the defect of ani- mal and vegetable matter must be supplied by animal or vegetable manure. 469. The general indications of fertility and barrenness, as found by chemical experiments, must necessarily differ in different cli- Tlirough how many stages of fermentation do vegetable and how many do animal substances pass during decomposition ? In what manner ought soils to be compared with a view to improve- ments in their composition ? What example of alteration in soil may illustrate this point? VVhat precaution is to be used in attempting to improve soils by means of lime ? flow is an excess of vegetable mould in any given soil to be obviated ? How is its deficiency to be supplied ? SOILS. 171 mates, and under different circumstances. The power of soils to absorb moisture, a principle essential to their productiveness, ought to be much greater in warm and dry countries than in cold and moist ones ; and the quantity of fine aluminous earth they contain should be larger. Soils likewise that are situate on declivities ought to be more absorbent than those in the same climate on plains or in valleys. 470. The productiveness of soils must likewise be influenced by the nature of the sub-soil, or the earthy or stony strata on which they rest ; and this circumstance ought to be particularly attended to, in considering their chemical nature, and the system of improvement. Thus a sandy soil may owe its fertility to the power of the sub-soil to retain water ; and an absorbent clayey soil may occasionally be prevented from being barren, in a moist climate, by the influence of a sub-stratum of sand or gravel. 471. Those soils that are most productive of corn, contain always certain proportions of aluminous or calcareous earth in a finely divided state, and a certain quantity of vegetable or animal matter. Mr. Tillet, in some experiments made on the composition of soils at Paris, found, that a soil composed of three-eighths of clay, two-eighths of river sand, and three-eighths of the parings of lime- stone, was very proper for wheat. 472. In general, bulbous roots require a soil much more sandy, and less absorbent, than the grasses. A very good potato soil, from Varsel, in Cornwall, afforded seven-eighths of siliceous sand ; and its absorbent power was so small, that 100 parts lost only 2 by drying at 400 Fahrenheit. Plants and trees, the roots of which are fibrous and hard, and capable of penetrating deep into the earth, will vegetate to ad- vantage in almost all common soils that are moderately dry, and do not contain a very great excess of vegetable matter. 473. From the great difference of the causes that influence the productiveness of lands, it is obvious, that in the present state of science no certain system can be devised for their improvement, independent of experiment; but there are few cases, in which the labour of analytical trials will not be amply repaid by the cer- tainty with which they denote the best methods of melioration ; and this will particularly happen, when the defect of composition is found in the proportions of the primitive earths. 474. In supplying animal or vegetable manure, a temporary food only is provided for plants, which is in all cases exhausted by "means of a certain number of crops; but when a soil is ren- What principle is essential to the productiveness of soils ? What influence may the rock over which any soil lies exercise on its productiveness ? What example may be adduced of this fact ? What ingredient seems peculiarly favourable to the production of grain ? What composition did Tillet find adapted to this purpose ? What soil is best adapted to bulbous roots ? What advantage do trees possess in regard to variety of soils ? Under what circumstances may we expect the greatest advantages from studying the chemical composition of soils ? 172 CHEMISTRY. dered of the best possible constitution and texture with regard to its earthy parts, its fertility may be considered as permanently established. It becomes capable of attracting a very large portion of vegetable nourishment from the atmosphere, and of producing its crops with comparatively little labour and expense. Analysis of Soils. 475. The substances found in soils are certain mixtures or com- binations of some of the primitive earths, animal and vegetable matter in a decomposed state, certain saline compounds, and the oxide of iron. These bodies always retain water, and exist in very different proportions in different lands, and the end of ana- lytical experiments is the detection of their quantities and mode of union. The earths commonly found in soils are principally silex, or the earth of flints; alumina or the pure matter of clay; lime, or cal- careous earth ; and magnesia. 476. Animal decomposing matter exists in different states, contains much carbonaceous substance, volatile alkali, inflamma- ble aeriform products, and carbonic acid. It is found chiefly in lands lately manured. Vegetable decomposing matter usually contains still more carbonaceous substance, and differs from the preceding, principally, in not producing volatile alkali. It forms a great proportion of all peats, abounds in rich mould, and is found in larger or smaller quantities in all lands. 477. The saline compounds are few, and in small quantity : they are chiefly muriate of soda, or common salt, sulphate of magnesia, muriate and sulphate of potash, nitrate of lime, and the mild alkalies. Oxide of iron, which is the same with the rust produced by exposing iron to air and water, is found in all soils, but most abundantly in red and yellow clays, and red and yellow siliceous sands. 478. The instruments requisite for the analysis of soils are few. A pair of scales capable of holding a quarter of a pound of com- mon soil, and turning with a single grain when loaded ; a set of weights, from a quarter of a pound troy to a grain ; a wire sieve, coarse enough to let a pepper-corn pass through ; an Argand lamp and stand ; a few glass bottles, Hessian crucibles, and china or queen's ware evaporating basin ; a wedgwood pestle and mortar; some filters made of half a sheet of blotting paper, folded so as to contain a pint of liquid, and greased at the edges ; a bone knife ; and an apparatus for collecting and measuring aeriform fluids. Why is it more important to ascertain a defect in soils with regard to the primitive earths than to the vegetable or animal ingredients? What variety of substances enter into the composition of soils? What four earths exist in the greatest abundance in soils ? On what lands is animal matter usually found ? Of what substances is it found to consist ? How do the vegetable differ from the animal components of soils? What are the saline ingredients of soils? What metallic oxide exists in them ? With what chemical apparatus may soils be analyzed ? ANALYSIS OF SOILS. 173 479. The reagents necessary are muriatic acid, sulphuric acid, pure volatile alkali dissolved in water, solution of prussiate of potash, soap lye, and solutions of carbonate of ammonia, muriate of ammonia, neutral carbonate of potash, and nitrate of ammonia. (1.) When the general nature of the soil of a field is to be ascertained, specimens of it should be taken from different places, two or three inches below the surface, and examined as to the similarity of their properties. It sometimes happens, that on plains the whole of the upper stratum of the lands is of the same kind, and in this case one analysis will be sufficient. But in val- leys, and near the beds of rivers, there are very great differences, and it now and then occurs, that one part of a field is calcareous, and another part siliceous ; in this and analogous cases, the por- tions different from each other should be analyzed separately. Soils, when collected, if they cannot be examined immediately, should be preserved in phials, quite filled with them, and closed with ground glass stopples. 480. The most convenient quantity for a perfect analysis is from two hundred grains to four hundred. It should be collected in dry weather, and exposed to the air till it feels dry. Its specific gravity may be ascertained, by introducing into a phial, which will contain a known quantity of water, equal bulks of water and of the soil; which may easily be done by pouring in water till the phial is half full, and then adding the soil till the fluid rises to the mouth. The difference between the weight of the water and that of the soil will give the result. Thus, if the bottle will contain four hundred grains of water, and gains two hundred grains when half filled with water and half with soil, the specific gravity of the soil will be 2 ; that is, it will be twice as heavy as water : and if it gained one hundred and sixty-five grains, its specific gravity would be 1825, water being 1000. It is of importance that the specific gravity of a soil should be known, as it affords an indication of the quantity of animal and vegetable matter it contains ; these substances being always most abundant in the lighter soils. The other physical properties of soils should like- wise be examined before the analysis is made, as they denote, to a certain extent, their composition, and serve as guides in direct- ing the experiments. Thus, siliceous soils are generally rough to the touch, and scratch glass when rubbed upon it ; aluminous soils adhere strongly to the tongue, and emit a strong earthy smell when breathed upon ; and calcareous soils are soft, and much less adhesive than aluminous soils. 481. (2.) Soils, when as dry as they can be made by exposure to the air, still retain a considerable quantity of water, which adheres What chemical tests are required ? In what manner ought specimens of soil for examination to be collected and preserved ? In what manner is the specific gravity of soils ascertained ? Why is this step important ? What other physical properties are to be tried ? P2 174 CHEMISTRY. with great obstinacy to them, and cannot be driven off without considerable heat : and the first process of analysis is to free them from as much of this water as possible, without affecting their composition in other respects. This may be done by heating the soil for ten or twelve minutes in a china basin over an Argand lamp, at a temperature equal to 300 F. ; and if a thermometer be not used, the proper degree of heat may easily be ascertained by keeping a piece of wood in the basin in contact with its bottom ; for as long as the colour of the wood remains unaltered, the heat is not too high ; but as soon as it begins to be charred, the process must be stopped. In several experiments, in which Sir H. Davy collected the water that came over at this degree of heat, he found it pure, without any sensible quantity of other volatile matter being produced. The loss of weight in this process must be carefully noted ; and if it amount to 50 grains in 400 of the soil, this may be considered as in the greatest degree absorbent and retentive of water, and will generally be found to contain a large proportion of aluminous earth. If the loss be not more than 10 or 20 grains, the land may be considered as slightly absorbent and retentive, and the siliceous earth as most abundant. 482. (3.) None of the loose stones, gravel, or large vegetable fibres, should be separated from the soil, till the water is thus ex- pelled ; for these bodies are often highly absorbent and retentive, and consequently influence the fertility of the land. But after the soil has been heated as above, these should be separated by the sieve, after the soil has been gently bruised in a mortar. The weights of the vegetable fibres or wood, and of the gravel and stones, should be separately noted down, and the nature of the latter ascertained : if they be calcareous, they will effervesce with acids; if siliceous they will scratch glass; if aluminous, they will be soft, easily scratched with a knife, and incapable of effervescing with acids. 483. (4.) Most soils, besides stones and gravel, contain larger or smaller proportions of sand of different degrees of fineness ; and the next operation necessary is to separate this sand from the parts more minutely divided, such as clay, loam, marl, and vege- table and animal matter. This may be done sufficiently by mixing the soil well with water ; as the coarse sand will generally fall to the bottom in the space of a minute, and the finer in two or three : so that by pouring the water off after one, two, or three minutes, the sand will be, for the most part, separated from the other sub- stances ; which, with the water containing them, must be poured into a filter. After the water has passed through, what remains on the filter must be dried and weighed, as must also the sand ; and their respective quantities must be noted down. The water What is ihe first step in examining the composition of a soil ? At what temperature may it be dried ? Why should not the pebbles be separated before drying ? How is sand to be separated from minute ingredients ? ANALYSIS OF SOILS. 175 must be preserved, as it will contain the saline matter, and the soluble animal or vegetable matter, if any existed in the soil. 481. (5.) A minute analysis of the sand thus separated is sel- dom or never necessary, and its nature may be detected in the same way as that of the stones and gravel. It is always siliceous sand, or calcareous sand, or both together. If it consist wholly of carbonate of lime, it will dissolve rapidly in muriatic acid, with effervescence ; but if it consist partly of this and partly of sili- ceous matter, a residuum will be left after the acid has ceased to act on it, the acid being added till the mixture has a sour taste, and has ceased to effervesce. This residuum is the siliceous part; which being washed, dried, and heated strongly in a crucible, the difference of its weight from that of the whole, will indicate the quantity of the calcareous sand. 485. (6.) The finely divided matter of the soil is usually very compound in its nature : it sometimes contains all the four primi- tive earths of soils, as well as animal and vegetable matter; and to ascertain the proportions of these with tolerable accuracy, is the most difficult part of the subject. The first process to be per- formed in this part of the analysis, is the exposure of the fine matter of the soil to the action of muriatic acid. This acid, diluted with double its bulk of water, should be poured upon the earthy matter in an evaporating basin, in a quantity equal to twice the weight of the earthy matter. The mixture should be often stirred, and suffered to remain for an hour, or an hour and a half, before it is examined. 486. If any carbonate of lime, or of magnesia, exist in the soil, they will have been dissolved in this time by the acid, which sometimes takes up likewise a little oxide of iron, but very sel- dom any alumina. The fluid should be passed through a filter ; the solid matter collected, washed with distilled or rain water, dried at a moderate heat, and weighed. Its loss will denote the quantity of solid matter taken up. The washings must be added to the solution ; which, if not sour to the taste, must be made so by the addition of fresh acid ; and a little solution of prussiate of potash must be mixed with the liquor. If a blue precipitate occur, it denotes the presence of oxide of iron, and the solution of the prussiate must be dropped in, till no further effect is produced. To ascertain its quantity it must be collected on a filter in the same manner as the other solid precipitates, and heated red : the result will be oxide of iron. ^87. Into the fluid freed from oxide of iron, a solution of car- bonate of potash must be poured, till all effervescence ceases in it, and till its taste and smell indicate a considerable excess of alkaline salt. The precipitate that falls down is carbonate of How may the nature of the sand be ascertained ? How are we to proceed in determining the finer portions of the soil ? What acid is first employed ? What ingredients will this acid dissolve ? . How may the solution be known to contain oxide of iron ? 176 CHEMISTRY. lime, which must be collected on a filter, dried at a heat helow that of redness, and afterwards weighed. The remain! ng fluid must be boiled for a quarter of an hour, when the magnesia, if there be any, will be precipitated combined with carbonic acid ; and its quantity must be ascertained in the same manner as that of the carbonate of lime. If any minute proportion of alumina should, from peculiar circumstances, be dissolved by the acid, it will be found in the precipitate with the carbonate of lime, and it may be separated from it by boiling for a few minutes with soap lye sufficient to cover the solid matter : for this lye dissolves alumina, without acting upon carbonate of lime. 488. (7.) The quantity of insoluble animal and vegetable mat- ter may next be ascertained with sufficient precision, by heating it to a strong red heat in a crucible over a common fire, till no blackness remains in the mass, stirring it frequently meanwhile with a metallic wire. The loss of weight will ascertain the quantity of animal and vegetable matter there was, but not the proportions of each. If the smell emitted, during this process, resemble that of burnt feathers, it is a certain indication of the presence of some animal matter; and a copious blue flame almost always denotes a considerable proportion of vegetable matter. Nitrate of ammonia, in the proportion of twenty grains to a hundred of the residuum of the soil, will greatly accelerate this process if the operator be in haste and not affect the result, as it will be decomposed and evaporate. 489. (8.) What remains after this decomposition of the vege- table and animal matter, consists generally of minute particles of earthy matter, which are usually a mixture of alumina and silex with oxide of iron. To separate these, boil them two or three hours in sulphuric acid diluted with four times its weight of water, allowing a hundred and twenty grains of acid for every hundred grains of the residuum. Mineral Waters. 490. The examination of mineral waters, with a view to acer- tain their ingredients, and thence their medicinal qualities, and the means of compounding them artificially, is an object of con- siderable importance to society. It is likewise a subject which deserves to be attended to, because it affords no mean opportunity for the agreeable practice of chemical skill. But this investiga- tion is more especially of importance to the daily purposes of life, and the success of manufactures. It cannot but be an inte- resting object, to ascertain the component parts and qualities of the By what reagent will the carbonate of lime be precipitated? How the carbonate of magnesia? How are the insoluble ingredients ascertained to contain animal mat- ter? How shall we be informed of the presence of vegetable ingredients? What circumstances render important the knowledge of the composition of mineral waters ? MINERAL WATERS. 177 waters daily consumed by the inhabitants of large towns and vicinities. A very minute portion of unwholesome matter, daily taken, may constitute the principal cause of the differences in salubrity which are observable in different places. And with re- gard to manufactures, it is well known to the brewer, the paper- maker, the bleacher, and a variety of other artists, of how much consequence it is to them, that this fluid should either be pure, or at least not contaminated with such principles as tend to injure the qualities of the articles they make. 491. The topography of the place where these waters rise is the first thing to be considered. By examining the ooze formed by them, and the earth or stones through which they are strained and filtered, some judgment may be formed of their contents. In filtering through the earth, and meandering on its surface, they take with them particles of various kinds, which their extreme attenuation renders capable of being suspended in the fluid that serve's for their vehicle. Hence we shall sometimes find in these waters, siliceous, calcareous, or argillaceous earth; and at other times, though less frequently, sulphur, magnesian earth, or, from the decomposition of carbonated iron, ochre. 492. The following are the ingredients that may occur in mine- ral waters : (1.) The gases found are common air, oxygen, hydrogen, and sulphuretted hydrogen. (2.) The acids, uncombined, are the carbonic, sulphuric, and boracic. (3.) The only free alkali is soda and the free earths, silex and lime. (4.) The only salts are sulphates, nitrates, muriates, carbonates, and borates. 493. The testing of mineral waters consists (1.) In the exami- nation of them by the senses : (2.) In the examination of them by reagents. The examination by the senses consists in observing the effect of the water, as to appearance, smell, and taste. The appearance of the water, the instant in which it is pumped out of the well, as well as after it has stood for some time, affords several indications, from which we are enabled to form a judgment concerning its contents. If the water be turbid at the well, the substances are suspended only, and not dissolved ; but if the water be clear and transparent at the well, and sometime intervenes be- fore it becomes turbid, the contents are dissolved by means of carbonic acid. 494. The presence of this gas is likewise indicated by small bubbles, that rise from the bottom of the well, and burst in the air while they are making their escape, though the water at the same time perhaps has not an acid taste. But the most evident To what branch of manufactures is the subject particularly related ? What is the first point to be considered ? Why? What four classes of substances exist in mineral waters ? In what two methods may we test the character of mineral waters ? How may we judge of the ingredients in water by the eye ? 178 CHEMISTRY. proof of a spring containing carbonic acid, is the generation of bubbles, on the water being shaken, and their bursting with more or less noise, while the air is making its escape. 495. The sediment deposited by the water in the well is like- wise to be examined : if it be yellow, it indicates the presence of iron ; if black, that of iron combined with sulphur ; but cha- lybeate waters being seldom sulphuretted, the latter occurs very rarely. As to the colour of the water itself, there are few in- stances where this can give any indication of its contents, as there are not many substances that colour it. The odour of the water serves chiefly to discover the presence of sulphuretted hy- drogen in it; such waters as contain this substance have a pecu- liar fetid smell, somewhat resembling rotten eggs. 496. The taste of a spring, provided it be perfectly ascertained by repeated trials, may afford some useful indications with respect to the contents. It may be made very sensible by tasting water in which the various salts that are usually found in such waters are dissolved in various proportions. There is no certain depen- dence, however, to be placed on this mode of investigation ; for in many springs the taste of sulphate of soda is disguised by that of the sea salt united with it. The water, too, is not only to be tasted at the spring, but after it has stood for some time. This pre- caution must be particularly observed with respect to such waters as are impregnated with carbonic acid ; for the other substances contained in them make no impression on the tongue, till the car- bonic acid has made its escape ; and it is for the same reason that these waters must be evaporated in part, and then tasted again. 497. Though the specific gravity of any water contributes but very little towards determining its contents, still it may not be entirely useless to know the specific w r eifjht of the water, the situation of the spring, and the kind of sediment deposited by it. 498. The examination of the water by means of reagents shows what they contain, but not how much of each principle. In many instances this is as much as the inquiry demands ; and it is always of use to direct the proceedings in the proper analysis. It is absolutely necessary to make the experiment with water just taken up from the spring, and afterward with such as has been exposed for some hours to the open air ; and sometimes a third essay is to be made with a portion of the water that has been boiled and afterward filtered. If the water contain but few saline particles, it must be evaporated ; as even the most sensible reagents do riot in the least affect it, if the salts, the presence of which is to be discovered by them, are diluted with too great a quantity of water. Now, it may happen, that a water shall be How is the presence of carbonic acid best ascertained ? What judgment may we form of water from the appearance of its sedi- ment? What kind of materials may the sense of smell help us to detect ? At what period may we rely on the sense of taste to indicate the cha- racter of water ? MINERAL WATERS. 179 impregnated with a considerable number of saline particles of dif- ferent kinds, though some of them may be present in too small a quantity ; for which reason the water must be examined a second time, after having been boiled down to three-fourths. 499. The substances of which the presence is discoverable by reagents are: Carbonic acid. When this is not combined with any base, or not with sufficient to neutralize it, the addition of lime water will throw down a precipitate soluble with effervescence in muriatic acid. The infusion of litmus is reddened by it; but the red colour gradually disappears, and may be again restored by the addition of more of the mineral water. When boiled, it loses the property of reddening the infusion of litmus. According to Pfaff, the most sensible test of this acid is acetate of lead. 500. The mineral acids, when present uncombined in water, give the infusion of litmus a permanent red, even though the water has been boiled. Bergmann has shown that paper, stained with litmus, is reddened when dipped into water containing 3^1 f sulphuric acid. Water containing sulphuretted hydrogen gas is distinguished by the following properties : It exhales the peculiar odour of sul- phuretted hydrogen gas. It reddens the infusion of litmus fuga- ciously. It blackens paper dipped into a solution of lead, and precipitates the nitrate of silver black or brown. 501. Alkalies, and alkaline and earthy carbonates, are distinguished by the following tests : The infusion of turmeric, or paper stained with turmeric, is rendered brown by alkalis; or reddish-brown, if the quantity be minute. This change is produced when the soda in water amounts only to -^ TTT P art - Paper stained with brasil wood, or the infusion of brasil wood, is rendered blue ; but this change is produced also by the alkaline and earthy carbonates. Bergmann ascertained that water containing j-^-^j part of carbonate of soda reddens paper, stained with brasil wood, blue. Litmus paper, reddened by vinegar, is restored to its original blue colour. This change is produced by the alkaline and earthy carbonates also. When these changes are fugacious, we may conclude that the alkali is ammonia. 502. Fixed alkalies exist in water that occasions a precipitate with muriate of magnesia after being boiled. Volatile alkali may be distinguished by the smell ; or it may be obtained in the re- ceiver by distilling a portion of the water gently, and then it may be distinguished by the above tests. Earthy and metallic carbonates are precipitated by boiling the water containing them ; except carbonate of magnesia, which is precipitated but imperfectly. How shall we be able to detect the presence of an ingredient which originally constitutes but a very small portion of the water ? What is the test of carbonic acid ? What is that of the mineral acids ? How is sulphuretted hydrogen detected ? What tests show the presence of alkalis and earthy carbonates ? 180 CHEMISTRY. 503. Iron is discovered by the following tests : The addition of tincture of galls gives water, containing iron, a purple or black colour. This test indicates the presence of a very minute portion of iron. If the tincture have no effect upon the water, after boiling, though it colours it before, the iron is in a state of a carbonate. The following observations of Westrumb on the colour which iron gives to galls, as modified by other bodies, deserves attention. A violet indicates an alkaline carbonate, or earthy salts. Dark purple indicates other alkaline salts. Purplish-red indicates sul- phuretted hydrogen gas. Whitish, and then black, indicates sul- phate of lime. 504. Sulphuric add exists in waters that form a precipitate with the following solutions : Muriate, nitrate, or acetate of baryta, strontia or lime, or nitrate or acetate of lead. Of these the most powerful by far is muriate of baryta, which is capable of de- tecting the presence of sulphuric acid uncombined, when it does not exceed the millionth part of the water. Acetate of lead is next in point of power. The muriates are more powerful than the nitrates. The calcareous salts are least powerful. All these tests are capable of indicating a much smaller proportion of un- combined sulphuric acid, than when it is combined with a base. To render muriate of baryta a certain test of sulphuric acid, the following precautions must be observed : The muriate must be diluted ; the alkalis or alkaline carbonates, if the water contain any, must be previously saturated with muriatic acid ; the preci- pitate must be insoluble in muriatic acid ; if boracic acid be sus- pected, muriate of strontia must be tried, which is not precipitated by boracic acid. The hydrosulphurets precipitate barytic solu- tions ; but their presence is easily discovered by the smell. 505. Muriatic acid is detected by nitrate of silver, which occa- sions a white precipitate, or a cloud, in water containing an exceedingly minute portion of this acid. To render this test cer- tain, the following precautions are necessary : The alkalis or carbonates must be previously saturated with nitric acid. Sul- phuric acid, if any be present, must be previously removed by means of nitrate of baryta. The precipitate must be insoluble in nitric acid. Pfaff says, that the mild nitrate of mercury is the most sensible test of muriatic acid ; and that the precipitate is not soluble in an excess of any acid. 506. Boracic acid is detected by means of acetate of lead, with which it forms a precipitate insoluble in acetic acid. But to ren- der this test certain, the alkalies and earths must be previously saturated with acetic acid, and the sulphuric and muriatic acids removed by means of acetate of strontia and acetate of silver. What test proves the presence of iron ? What rule will enable us to judge what compound of iron is present in water ? What is the test for sulphuric acid ? What will prove the presence of muriatic acid ? What of boracic acid ? MINERAL WATERS. 181 Baryta is detected by the insoluble white precipitate which it forms with diluted sulphuric acid. 507. Lime is detected by means of oxalic acid, which occasions a white precipitate in water containing a very minute proportion of this earth. To render this test decisive, the following pre- cautions are necessary: The mineral acids, if any be present, must be previously saturated with an alkali. Baryta, if any be present, must be previously removed by means of sulphuric acid. Oxalic acid precipitates magnesia but very slowly, whereas it precipitates lime instantly. 508. Magnesia and alumina. The presence of these earths is ascertained by the following tests : -Pure ammonia precipitates them both, and no other earth, provided the carbonic acid have been previously separated by a fixed alkali and boiling. Lime- water precipitates only these two earths, provided the carbonic acid be previously removed, and the sulphuric acid also, by means of nitrate of baryta. The alumina may be separated from the magnesia, after both have been precipitated together, either by boiling the precipitate in caustic potash, which dissolves the alumina and leaves the magnesia ; or the precipitate may be dissolved in muriatic acid, precipitated by an alkaline carbonate, dried in the temperature of 100 degrees, and then exposed to the action of diluted muriatic acid, which dissolves the magnesia without touching the alu- mina. 509. Sllex may be ascertained by evaporating a portion of water to dryness, and redissolving the precipitate in muriatic acid. The silex remains behind undissolved. By these means we may detect the presence of the different substances commonly found in waters ; but as they are generally combined so ^s to form salts, it is necessary we should know what these combinations are. This is a more difficult task, which Mr. Kirwan teaches us to accomplish by the following methods : 510. (1.) To ascertain the presence of the different sulphates. The sulphates which occur in water are seven ; but one of these, namely, sulphate of copper, is so uncommon, that it may be excluded altogether. The same remark applies to sulphate of ammonia. It is almost unnecessary to observe, that no sulphate need be looked for, unless both its acid and base have been previously detected in the water. 541. Sulphate of soda may be detected by the following method : Free the water to be examined of all earthy sulphates, by evaporating it to one-half, and adding lime-water as long as What will prove the presence of baryta ? What of lime? How are we to know whether magnesia and alumina are contained in mineral water? What method separates the silex if any be present ? Q 182 CHEMISTRY. any precipitate appears. By these means the earths will all be precipitated except lime, and the only remaining earthy sulphate will be the sulphate of lime, which will be separated by evapo- rating the liquid till it becomes concentrated, and then dropping into it a little alcohol, and, after filtration, adding a little oxalic acid. 512. With the water thus purified, mix solution of lime. If a precipitate appear, either immediately, or on the addition of a little alcohol, it is a proof that sulphate of potash or of soda is present. Which of the two may be determined, by mixing some of the purified water with acetate of baryta. Sulphate of baryta preci- pitates. Filter and evaporate to dryness. Digest the residuum in alcohol. It will dissolve the alkaline acetate. Evaporate to dryness, and the dry salt will deliquesce if it be acetate of potash, but effloresce if it be acetate of soda. 513. Sulphate of lime may be detected by evaporating the water suspected to contain it to a few ounces. A precipitate appears, w r hich, if it be sulphate of lime, is soluble in 500 parts of water, and the solution affords a precipitate with the muriate of baryta, oxalic acid, carbonate of magnesia, and alcohol. 514. Alum may be detected by mixing carbonate of lime with the water suspected to contain it. If a precipitate appear, it in- dicates the presence of alum, or at least of sulphate of alumina ; provided the water contains no muriate of baryta or metallic sul- phates. The first of these salts is incompatible with alum ; the second may be removed by the alkaline pmssiates. When a pre- cipitate is produced in water by muriate of lime, carbonate of lime, and muriate of magnesia, we may conclude that it contains alum or sulphate of alumina. 515. Sulphate of magnesia may be detected by means of hy- drosulphuret of strontia, which occasions an immediate precipitate with this salt, and with no other ; provided the water be pre- viously deprived of alum, if any be present, by means of carbo- nate of lime, and provided also that it contains no uncombined acid. Sulphate of iron is precipitated from water by alcohol, and then it may be easily recognised by its properties. 516. (2.) To ascertain the presence of the different muriates. The muriates found in waters amount to eight, or to nine, if muriate of iron be included. The most common by far is muriate of soda. Muriate of soda and of potash may be detected by the following method : Separate the sulphuric acid by alcohol and nitrate of baryta. Decompose the earthy nitrates and muriates by adding sulphuric acid. Expel the excess of muriatic and nitric acids by heat. Separate the sulphates thus formed by alcohol and baryta water. The water thus purified can contain nothing but alkaline nitrates and muriates. If it form a precipitate with acetate of silver, we may conclude that it contains muriate of soda or of How shall the presence of sulphate of soda be known ? sulphate oflime ? of alumina ? of magnesia ? of iron? $ MINERAL WATERS. 183 potash. To ascertain which, evaporate the liquid thus preci- pitated to dry ness. Dissolve the acetate in alcohol, and again evaporate to dryness. The salt will deliquesce, if it be acetate of potash, but effloresce if it be acetate of soda. 517. The potash salts are most readily distinguished by the precipitate which they afford to muriate of platinum, which the soda salts do not occasion. Muriate of baryta may be detected by sulphuric acid, as it is the only barytic salt hitherto found in water. Muriate of lime may be detected by the following method : Free the water from sulphate of lime and other sulphates, by evaporating it to a few ounces, mixing it with alcohol, and adding last of all nitrate of baryta as long as any precipitate appears. Filter the water, evaporate to dryness ; treat the dry mass with alcohol ; evaporate the alcohol to dryness ; and dissolve the re- siduum in water. If this solution give a precipitate with acetate of silver and oxalic acid, it may contain muriate of lime. It must contain it in that case, if, after being treated with carbonate of lime, it give no precipitate with ammonia. If the liquid in the receiver give a precipitate with nitrate of silver, muriate of lime existed in the water. 518. Muriate of magnesia may be detected by separating all the sulphuric acid by means of nitrate of baryta. Filter, evaporate to dryness, and treat the dry mass with alcohol. Evaporate the alcoholic solution to dryness, and dissolve the residuum in water. The muriate of magnesia, if the water contained any, will be found in this solution. Let us suppose, that, by the tests formerly described, the presence of muriatic acid and of magnesia, in this solution, has been ascertained. In that case, if carbonate of lime afford no precipitate, and if sulphuric acid and evaporation, to- gether with the addition of a little alcohol, occasion no precipi- tate, the solution contains only muriate of magnesia. If these tests give precipitates, we must separate the lime which is present by sulphuric acid and alcohol, and distil off the acid with which it was combined. Then the magnesia is to be separated by oxalic acid and alcohol, and the acid with which it was united is to be distilled off. If the liquid in the retort give a precipitate with nitrate of silver, the water contains muriate of magnesia. 519. Muriate of alumina may be discovered by saturating the water, if it contain an excess of alkali, with nitric acid, and by separating the sulphuric acid by means of nitrate of baryta. If the liquid, thus purified, give a precipitate with carbonate of lime, it contains muriate of alumina. The muriate of iron, or of man- ganese, if any be present, is also decomposed, and the iron pre- cipitated by this salt. 520. Such are the methods by which the presence of the dif- ferent saline contents of waters may be ascertained. The labour How shall we proceed to find whether water contains muriate of soda or of potash ? muriate of baryta ? of lime ? of magnesia ? of alumina ? 1 84 CHEMISTRY. of analysis may be considerably shortened by observing, that the following salts are incompatible with each other, and cannot exist together in water, except in very minute proportion : Salts. Incompatible with Fixed alkaline sulphates J" ^ itr . ate of f l e and , ma g nesia ' Muriate of lime and magnesia. r Alkalies, Sulphate of lime . . < Carbonate of magnesia, C Muriate of baryta. ("Alkalies, Alum J Muriate of baryta, j Nitrate, muriate, carbonate of lime, (_Carbonate of magnesia. r Alkalies, Sulphate of magnesia . < Muriate of baryta, C. Nitrate and muriate of lime. r Alkalies, Sulphate of iron . . < Muriate of baryta, C Earthy carbonates. r Sulphates, Muriate of baryta . . < Alkaline carbonates, C Earthy carbonates. ("Sulphates, except of lime, Muriate of lime . . < Alkaline carbonates, C. Earthy carbonates. Muriate of magnesia . r Alkaline carbonates, Nitrate of lime . . . < Carbonate of magnesia and alumina, C. Sulphates, except of lime. 521. Beside the substances above described, there is sometimes found in water a quantity of bitumen combined with alkali, and in the state of soap. In such waters, acids occasion a coagulation ; and the coagulum collected on a filter discovers its bituminous nature by its combustibility. 522. Water also sometimes contains extractive matter; the presence of which may be detected by means of nitrate of silver. The water suspected to contain it, must be freed from sulphuric and nitric acid by means of nitrate of lead ; after this, if it give a brown precipitate with nitrate of silver, we may conclude that extractive matter is present. How may the labour of analysis be often abridged ? What substances are incompatible in mineral water with fixed alkaline sulphates? with sulphate of lime? with alum? with sulphate of mag- nesia ? with sulphate of iron ? with muriate of baryta ? of lime ? of magnesia ? with nitrate of lime ? How is the presence of bitumen detected ? How that of extractive matter? MINERAL WATERS. 185 Works in the Department of Chemistry. In this and the other lists of works appended to the several treatises contained in the Scientific Class Books, the works first named are, in general, those supposed to be most easily procured by the student, and they are commonly the most familiar and popular in their modes of treating their respective subjects. The latter titles in each list are those of works supposed to be met with principally in public libraries. Turner's Chemistry, new edition, by Dr. Franklin Bache. Philadelphia. 1835. Webster's Manual of Chemistry, on the Basis of Brande's, 1 vol. 8vo. Henry's Chemistry, 2 vols. 8vo. Philadelphia. Farraday's Chemical Manipulations, edited by Dr. J. K. Mit- chell. Philad. 1 vol. 8vo. Dr. Hare's Compendium of Illustrations in Chemistry, &c. 1 vol. 8vo. Ure's Chemical Dictionary. 1 vol. 8vo. Porter's Chemistry of the Arts, on the Basis of Gray's Operative Chemist. Philad. 1 vol. 8vo. Silliman's American Journal of Science, passim. Transactions of the British Association. Berzelius's Chemistry. Paris edition. Annales de Chemie et de Physique. METALLURGY. 1. THE term metallurgy in its most extensive signification, de- notes the working of metals, and may thus include all operations connected with the raising of metallic ores from mines, or procuring them from metalliferous sands ; those employed for ascertaining the value of minerals whence metals are obtained; the multifarious processes relative to the extraction of the various metals from their respective ores ; and the still more numerous processes which relate to manufactures of hardware, steel, tin-plate, brass, bronze, gold and silver plate, as well as of other metals and their combinations. But metallurgy in a more restricted sense, is to be regarded as a department of chemistry, comprising the description and rationale of those chemical operations by means of which the useful metals and their alloys are separated from the saline, earthy, or stony substances in conjunction with which they are presented to us by nature. ^Under this point of view the subject will be treated in the following pages; but some preliminary notices of metallic veins, mines, and the art of mining, may be introduced, as being both interesting and instructive, tending to illustrate the proper- ties and composition of those substances to which the attention of the metallurgist or metallurgic chemist is principally directed. Docimasties, or the art of assaying, as a process preceding the reduction of metals, will also demand our attention. , / Mineral Deposits and Mines. 2. Nature presents metallic substances to our notice scattered on the surface or inclosed within the crust of the terrestial globe, cither in a state of purity, or in combination with various other bo- dies. These combinations are properly termed mineralized metals, or ores; metals in this state being united to extraneous matter, which alters their properties in such a manner, that their real nature can only be ascertained by chemical analysis. Sometimes two or more metals are combined with the same mineralizing body ; frequently a single metal is united with several such bodies, and yet more frequently, in mines, are found combinations consisting of several metals and various mineralizing bodies united together. 3. A few only of the metals (almost exclusively those which are termed precious metals) are found in a state of purity dis- persed through the soil of valleys, or mixed with the sand of What is the origin and use of the term metallurgy ? What may it include in its most extensive sense? What is its most restricted meaning ? What is meant by docimastics ? In what states are metallic substances found in nature ? * From the Greek MeraXAov, metal, and v Eoypv, work. 186 MINERAL BEDS. 187 rivers, or with earthy matter deposited by mountain torrents. It is thus that gold and platina, and especially the former, frequently occur in masses, often minute, sometimes of several pounds weight, and at all intermediate sizes, in alluvial soil, from which the metal is separated principally by mechanical means. Both metallic ores and native metals are occasionally disseminated in grains through rocks, and when they are thus found in abundance, the whole mass of the rock is worked as a mine ; but this is com- paratively seldom the case. V Tinstone, or the oxide of tin, is sometimes thus dispersed through the substance of granitic rocks in Cornwall, but this is generally observed in the vicinity of veins of tin ore.? This metal is likewise found in alluvial soil, in small nodular masses of considerable specific gravity, called stream-tin from the manner in which it is procured,-by washing the metallife- rous sand. 4.\.Mineral deposits, however, more usually occur in subterrane- ous beds or veins.-* (Metallic ores of some kinds form regular strata, or mineral beds, in secondary rocks, or in the more ancient transition and primary rocks.". These beds are in general horizon- tal, but they are sometimes observed to be highly inclined, and such strata have been mistaken for veins. \ The ores of copper, iron and lead r are occasionally found in conjunction in beds in primitive mountains, sometimes having gold or silver intermixed with them. Cobalt, and certain ores of mercury, likewise form strata. Iron ore is frequently found in beds of great thickness, in- terposed^ among rocks of gneiss, mica-slate, and clay-slate. Lead, zinc, manganese, and iron ores also occur abundantly in strata in secondary mountains. 5. \When a bed of metallic ore expands irregularly, it sometimes forms masses of such magnitude as to resemble small mountains, as is the case with iron ore in Sweden and Norway. Metallic beds, however, are generally of limited extent, seldom traversing an entire mountain, but gradually or suddenly terminating in a thin edge ; in the language of the miners, a stratum of ore is said to wedge out.} Beds of minerals are not of frequent occurrence in England, most of the great deposits of metallic matter in that country being found in veins, as is uniformly the case in the great mining districts of Cornwall, except in the previously noted stream-works. Mr. Bakewell, however, alleges that beds of cop- per pyrites have been wrought in transition rocks in Cumberland, What varieties in the degree of complexity exist in metallic mine- rals? What class of the metals are met with in nature in a slate of purity ? In what situations do they occur? In what forms does the ore of tin occur ? What is the most usual form of mineral deposits? How do ores of copper, iron, and lead exist ? What kinds of rocks are traversed by beds of iron ore? What ores may be found in strata in secondary mountains ? What is meant by wedging out ? 188 METALLURGY. and that the existence of mineral beds may be suspected in other counties, where they are often confounded with veins by the la- bouring miners. 6. Mineral veins, from their relative frequency, constitute the most considerable depositories of metallic matter. Such veins are not, as may be supposed from the general application of the term, tubes filled with metal or ore, but extended plates, or laminae, of unequal thickness ; and they differ most essentially from beds, in that they do not run parallel with the direction of other strata, but traverse or cross them vertically, or at various degrees of inclina- tion. A vein may be described as a fissure in a rock, filled with various substances. Humboldt noticed a vein of calcareous spar 140 feet in thickness, traversing gneiss, in the Alps of Switzer- land ; and Professor Jameson mentions a vein of porphyry slate, nearly 160 feet wide, occuring in sandstone, in the Isle of Arran, and veins of pitchstone and greenstone, varying in width from ten to one hundred feet. But these do not appear to have been of the nature of metalliferous veins which are commonly much narrower ; yet it is said, that in the silver mines of Pasco, in Peru, there is a vein of brown ironstone, containing silver, which is 1300 yards in width. 7. When metallic ores are worked in beds, or in veins of con- siderable thickness, that part of the rock which covers the ore is called the roof, and that which supports it the floor. These terms, however, are principally applicable to mines worked in an hori- zontal direction. The metalliferous veins of Cornwall which are of most importance, namely, those producing tin and copper, ex- tend nearly in the direction of east and west, with little variation. Though there are other veins, either destitute of metallic matter, or else containing lead and silver, which chiefly run north and south. The veins of Cornwall scarcely ever descend vertically, or exactly at right angles with the horizon, but almost always dip from the line of descent ; and this deviation from the perpendicu- lar is called by miners the hading of the vein ; thus a vein may be said to hade or dip to the north or south. 8. Metalliferous veins in general seem to observe no great uniformity of direction, some descending almost perpendicularly, and others very obliquely, in such a manner that in a single hill instances may be observed in which veins of different descriptions dip or underlie in almost all directions, traversing each other in such a manner as to defy the calculations of the miner. The head of a vein sometimes rises to the surface of the soil, and may thus be discovered ; and its existence is occasionally betrayed by To what is the term mineral veins applied ? In what do they differ from strata ? What is meant by the roof and what by the floor of a mine ? What has been observed in regard to the direction of metallic veins? What is meant by the hading of a vein ? VEINS. 189 a certain ochraceous or rust-like appearance, which may be ob- served above its site, but this is not very common. 9. To what depth metallic veins may descend, has never been ascertained, for no instance has yet occurred, of the termination of a vein being reached, though sometimes veins are found to become so thin and unproductive as not to repay the labour of working deeper, but more frequently the progress of the miner is stopped by water or other obstacles. Some of the Cornish mines are said to be nearly 500 yards in depth from the surface, as the copper and tin mine of Dolcoath, which is 456 yards deep ; and there are several the depth of which is from 300 to 400 yards. 10. The same vein sometimes contains different ores at different depths : thus the ores of iron, copper, cobalt, and silver are found successively in some of the mines in Saxony; and in France there are mines containing iron ore, below that silver ore, and in the lowest part copper ore. In Cornwall sulphuret of zinc, or blende, is found abundantly in the upper part of veins, which lower down are rich in copper, and sometimes tin in the same manner occurs in the superior part of a copper vein. 11. The thickness of veins, as already observed, is extremely variable, the same vein may be in some parts but a few inches wide, and in others extend to the thickness of many feet, or even yards. The vein at Dolcoath mine varies from two feet to forty ; and in some places is contracted to about six inches. 12. The veins, independent of their extent, may be characterized as rich or poor. In a Cornish mine called Whealan Cotes, was found a vein of tin ore about three inches wide, yet so rich as to be worth working. Some of the veins containing copper, in Herland mine, did not exceed six inches in width, and after thus continuing for a few fathoms, they passed away east and west into mere strings, or rather laminae, scarcely thicker than paper ; but these veins yielded ore of a rich quality. The thin veins or threads of metallic matter which sometimes occur in working mines, may be worth pursuing, independent of their product of metal, as they may lead to veins of much greater thickness, or to bunches, or large masses of metal. 13. Veins are by no means entirely filled with metalliferous matter, which, in fact, occupies comparatively but a small space, the veins including minerals of different descriptions. The non- metalliferous parts of a vein, of whatever nature they may be, are usually termed by the miner deads, as being unproductive and use- What is known of the depth of metallic veins? What facts have been ascertained in regard to the situation of different metallic ores in the same mine ? What degree of uniformity in regard to thickness characterizes metallic veins ? What difference independent of direction, inclination, depth, and thick- ness is it important to consider in regard to metallic veins ? To what is the term deads applied among miners ? 190 METALLURGY. less. Large empty spaces occasionally occur in veins, but this is not often the case. Water is found in large quantities in mines, especially those which are rich in tin or copper. The sides of metalliferous veins are usually very determinate, being covered by a hard, dark-coloured incrustation, called by the miner the walls of the vein : and there likewise commonly runs down every vein a small seam of whitish clayey matter, sometimes adhering to one side of the vein, and sometimes to the other. 14. The same substance which constitutes the incrustation of the veins, is also often intermixed with the ore, forming with it alternating layers, and with other substances composing what is called the matrix, gangue, or veinstone of the mineral. Different metals are accompanied by different kinds of gangue, the nature of which may enable the miner to form a judgment as to the pro- bable value of the vein. Among the substances thus found may be mentioned quartz, calcareous spar, fluor spar, called in Derby- shire blue John, and sulphate of barytes, also called cawk ; besides which, the ores of one metal are thus accompanied by those of another, and frequently by pyrites, (sulphuret of iron.) * 15. It has been already stated that in Cornwall tin and copper mines uniformly run in the direction of east and west, and that other veins, extending north and south, scarcely ever contain a trace of either of those metals, being non-metalliferous, or else af- fording the ores of silver, lead, cobalt, or iron, or occasionally antimony. These north and south veins are most commonly filled by quartz, by a whitish or bluish argillaceous substance, or by a kind of ochre, and sometimes by all three. When such a vein meets with another containing tin or copper, it passes through the tin or copper vein without interruption, while the latter becomes split, or frittered into numerous small branches, and sometimes its contents seem to be dissipated, so that the miner loses all traces of the vein, or only recovers it after a tedious search at the distance of perhaps between 400 and 500 feet. North and south veins dif- fer greatly in breadth, but whatever be their dimensions, they always divide the tin or copper veins which they encounter, and generally alter the direction of the latter, or, in the language of the miner, heave them out their course. 16. The manner in which metalliferous veins are sometimes in- terrupted by others, may be illustrated by the following section of the mine of Tincroft, in Cornwall : \Vhst is mount by TncttTix ? Of what materials is the matrix of ore often composed ? What difference has been observed in the veins of the same mine which vary in direction ? What class of veins in Cornwall appears to have divided and heaved another at right angles to it ? CROSSING OF VEINS. 191 A, B, represents the surface of the mine with a vein running from north to south, and crossed by tin and copper veins, from east to west. The veins, C, D, E, are veins of copper, F, G, H, veins of tin, and I, a vein yielding both tin and copper. Two of the cop- per, and one of the tin veins, running east and west, are intersected by the non-metalliferous north and south veins, by which they are heaved out of their regular course towards the south. It may also be perceived that one of the tin veins, F, is intersected by two of, the copper veins, C and D, which pass through it without affect- ing its direction. 17. The manner in which copper veins intersect those of tin, always passing through them, and generally heaving them from their course, may be understood from the following section of the Pink mine : N A, B, may be supposed to represent the surface, along which runs a vein from north to south, intersecting metalliferious veins, passing from east to west. The veins C, D, E, are copper veins, Construct and explain the plan of Tincroft mine ? Exhibit and explain the manner of heaving out a tin vein by one of copper. 192 METALLURGY. and F, a vein of tin ; and here it will be seen how three of these veins have their western sides heaved towards the north, by the non-metalliferous vein passing through them. The tin vein run- ning near the southern extremity of the mine, underlies greatly towards the north, while the copper veins, on the contrary, under- lie towards the south. One of the latter veins, C, meeting the tin vein, F, in its course, interrupted it, and heaved that part of it northward of the point of intersection twenty-four fathoms nearer to the surface, and the same tin vein was interrupted by another copper vein, D, and heaved about ten fathoms towards the sur- face; a third time it was cut through by another copper vein, E, not shown on the surface, and again heaved somewhat out of its course. 18. Sometimes one vein crosses another without causing any change of direction, and if both have nearly the same inclination, they are usually richer near their junction. Where two veins in the same district have the same direction, or run parallel, it has been observed that their contents are similar; but where they run in contrary directions, their contents are dissimilar. 19. Molina, in his History of Chili, gives an account of a vein of silver at Uspalta, in the Andes, which is nine feet in thickness throughout its extent, having been traced ninety miles ; and it has smaller veins branching off on either side, and penetrating the adjacent mountains to the distance of thirty miles. It has been conjectured that this vein reaches 300 miles. 20. In Northumberland and Durham, cross courses have been found to contain ore near their junction with strong veins. In Cornwall, at Botallac mine, near the Land's End, a cross course run- ning north and south, is enriched by the junction of east veins, which have been compared to small rivulets opening into a river. The cross course is rich in ore to the extent of twenty or thirty fathoms on either side of its junction with a vein, but no veins are found branching from the west side of the cross course. The vein contains gray copper ore of a fine quality. Sometimes a vein contains tin ore in the centre, sur- rounded laterally by copper ore, as repre- sented in the marginal figure. In this vertical section of a part of the vein, T denotes the central portion, con- sisting of tin, and C, C, the copper ore on each side of it.* What remark has been made respecting the junction of two veins which do not displace one another in crossing ? What description has been given of a vein of silver ore in South America? What example is found among the Cornish mines of cross courses enrich- ing the main vein ? In what arrangement are the ores of tin and copper sometimes placed within a common vein ? * Bakewell's Introd. to Geology, Silliman's ed. p. 300. GOLD PLATINA SILVER. 193 21. The different metals are found respectively in different parts of the world, in various situations, and associated with peculiar kinds of rocks, stones, sand, or alluvial soil. Gold is found in America, in Mexico, Brazil, New Granada, Chili. Peru, and Buenos Ayres ; in the United States it is found in Alaba- ma, Georgia, North and South Carolina, Virginia, and probably in some of the states farther north ; in Africa, in Kordofan, Bambouk, and on the eastern coast opposite the island of Madagascar, and especially in Sofala, supposed to be the country of Ophir, mentioned by the Jewish writers ; in Asia, in Thibet, Japan, Formosa, Cey- lon, Java, Sumatra, Borneo, the Philippines, and other islands of the Indian Archipelago, in Siberia, in the Ural and Altai mountains, between the rivers Obi and Irtisch ; in Europe, in Hungary, Tran- sylvania, the country round Salzburg, and the Hartz mountains, in Piedmont, in Spain, chiefly in the Asturias, and the Pyrenees, in France, in rivers occasionally in small quantities, and formerly in Thrace, Macedonia, and some of the Greek islands. 22. Gold occurs in primary and transition rocks, in porphyry and syenite, and in the lowest sandstone ; it has been occasionally found in coal, and sometimes in volcanic rocks, and most abun- dantly in the sands of rivers, or in that mixture of alluvial matter called cascalhao, consisting of pebbles, gravel, and minute parti- cles of siliceous and argillaceous earths, and oxide of iron. It is usually in the state of grains, minute scales, or pellets of various sizes, and it is thus collected by the African negroes, and brought for sale in ostrich and vulture quills. Sometimes it is met with in large masses ; in 1730, a block was discovered in Peru, weighing forty-five pounds; and about 1810, gold was obtained from several rivers in North Carolina, one mass weighing twenty-eight pounds. This metal is sometimes disseminated in threads or in lamina?, alloyed with tellurium and silver, and it is likewise mixed with the sulphurets of iron, of silver, of copper, of arsenic, of mercury, and other metals. 23. Platina was first discovered in the provinces of Choco and Bogota in South America, and it has since been found in the pro- vince of "Barbacoas, near the shores of the South Sea; in Brazil, in the island of St. Domingo, in North America, in very minute quantities in ores of argentiferous grey copper at Guadalcanal and Casalla, in Spain ; and recently in greater abundance on the west- ern or European side of the Ural mountains, in the territories of Russia. It occurs generally in the sands of rivers, intermixed with^ palladium, rhodium, osmium, iridium, and other metals. 24. Silver is found in America, in Mexico, Peru, Chili, and In what countries of the world is gold found ? In what species of rocks is it discovered ? Where is it found in the greatest abundance ? What remarkable masses of native gold have been met with ? Where is platina found in the greatest abundance in the present day ? In what situations does it occur ? With what other metals is it intermixed ? E 194 METALLURGY. Buenos Ayres ; in Asia, in China, Thibet, and Siberia ; in Europe, in Norway, Sweden, Hungary, Saxony, Transylvania, Moravia, Austria, Bohemia, the Tyrol, Hanover, Brunswick, Prussia, the Netherlands, France, Savoy, and Great Britain; but in the latter only as a subordinate product of lead or copper ores. It occurs principally in veins in primitive rocks, and in some transition and secondary rocks. 25. Lead is found in America, in Mexico, Brazil, and the United States ; in the Russian empire in the environs of Nertschinsk on the frontiers of Chinese Tartary, and in Armenia; in Europe, in France, Savoy, the Netherlands, the Prussian States, the Hartz Mountains, in Saxony; in the Austrian dominions and other parts of Germany; in England, especially in Derbyshire and Lancashire; in Scotland, In Ireland, and in Spain. Galena, which is the most common ore of lead, occurs in primitive as well as secondary rocks, and in Great Britain the richest mines are in slate and limestone. Lead ores are found generally in the older rocks, except trap and serpentine ; in porphyry and syenite, in the lowest sandstone, and occasionally in strata of coal. 26. Copper is found in Eurvpe, in France, Germany, Tran- sylvania, Silesia, Sweden, Norway, Great Britain, Ireland, and Spain ; in Asia, in Siberia, Kamtschatka, Japan, China, Per- sia, Arabia, and the Indian Islands ; in Africa, in Barbary, Mo- rocco, Abyssinia, in the mountains north of the Cape of Good Hope, and in the Namaqua country; in America, jn the North- western Territory, in Pennsylvania, and various other parts of the United States, in Mexico, Chili, and Brazil, in which last coun- try a mass was discovered weighing 2(>66 Portuguese pounds. It occurs in primitive and transition rocks, porphyry, syenite, and sometimes in sandstone, in coal strata, and alluvial soil. 27. Tin is found in England more abundantly than in most other countries, mines or tin-works of some kind having existed in Britain before it was known to the Romans, and it was imported from that island by the mariners of Phenicia and Carthage. The other parts of Europe in which it principally occurs, are Saxony, Bohemia, and France : the quantity found in Spain and Portugal is inconsiderable. In Asia it is found in China, Siarn, Pegu, in Sumatra, Ceylon, Banca, and other islands ; and in America, in Mexico and Buenos Ayres. It is considered as one of the most ancient of rnetals, having been discovered only in primitive rocks, as granite, gneiss, mica-slate, and clay-slate, or disseminated in soils formed from the decomposition of such rocks. 28. Mercury is found in Europe, in France, Bavaria, the Aus- trian dominions, and Spain, and in Italy arid Sicily, but in com- paratively small quantities ; in Asia the most productive mines In what countries "has silver been found ? In what class of rocks are lead ores most abundant ? What countries possess mines of copper? In what variety of rocks or soils does it occur ? Why is tin regarded as among the oldest metals? NICKEL. 195 are in China and Japan ; and in America., in Mexico and Peru, especially that of Guancavelica. Mercury differs from the metal just noticed, occurring but rarely and in small quantities in primi- tive countries, the principal deposits being found in bituminous slate, shell-limestone, and breccias. Dolomieu discovered it among the products of volcanoes, doubtless sublimed by subter- ranean fires. 29. Iron is the most abundant of metals in every part of the world, and is found in Europe, in England, Scotland, in Ireland more rarely, in France, Sweden, Norway, the Austrian empire, in the southern part of Russia, in Bavaria, Prussia, Saxony, Hesse, the Netherlands, Switzerland, Savoy, Piedmont, Naples,* Sardinia, Elba, Spain, and Portugal; in Jlsia, in Siberia, Arme- nia, Natolia, Persia, Arabia, Tartary, Indostan and China; in Africa, in Morocco, and in Congo ; and in America, abundantly in several of the United States, in Mexico, and Brazil. This metal is so generally diffused throughout the mineral kingdom, that, as Mr. Brande observes, " there are comparatively few fossils which can be said to be perfectly free from it." There is no kind of rock or formation primitive, transition, secondary, alluvial, or volcanic in which it does not make its appearance ; and its saline combinations, being dissolved in subterraneous waters, form chaly- beate springs. 30. The principal mines of Antimony, in Europe, are those ot Scotland, Hungary, Bohemia, Saxony, France, Spain, Transylva- nia, and at Neuweid, below Coblentz, on the right bank of the Rhine; and in America, in Mexico and Brazil. It occurs in primi- tive and transition rocks, exclusive of trapp and serpentine ; and likewise in porphyry and syenite. 31. Bismuth is obtained in England, France, Germany, and Sweden ; in Siberia and in Brazil ; chiefly from mines of other metals. It appears to belong exclusively to primitive countries. 32. Zinc is found in Belgium, in the territory of Limburg, in Prussia, Austria, France, Spain, and England ; in Siberia, where the mines are not worked ; and in America. It occurs in primi- tive, transition, and secondary rocks, calcareous, argillaceous, and siliceous. 33. Cobalt is found in Saxony, Austria, Prussia, Hesse, and other parts of Germany, Norway, and Sweden ; likewise in France and Spain, but the mines are not worked. It occurs in primitive mountains, except those of limestone, trapp, and serpen- tine; and likewise in transition mountains, and in sandstone. In what countries is mercury found in the greatest abundance ? In what classes of rocks is it met with ? Which of the metals is found in the greatest abundance in nature? What has been remarked of its prevalence in various geological forma- tions ? In what countries and in what class of rocks does antimony oc- cur ? bismuth ? zinc ? cobalt ? * Oxidulated iron is said to have been collected on the sea-shore, near Puzzuoli. 196 METALLURGY. 34. Nickel is found in France, Spain, Bohemia, and in England more rarely; likewise in Siberia; and it is a general, if not a constant component part of aerolites. This metal, which is one of the least abundant, is usually met with in the same situations with cobalt and arsenic, accompanying the ores of those metallic bodies. 35. Manganese is among the products of the mines of England, Scotland, France, Hungary, Transylvania, Saxony, and Bohemia. It is found in primitive and transition mountains, and sometimes in the lower stratified rocks. 36. Chrome occurs in France, Norway, the Tyrol, and at Eka- therineberg, in the Ural Mountains. It is generally embedded in gneiss or mica-slate. 37. Arsenic is found in Saxony, Silesia, Baden, Hungary, and Transylvania; and in England, in Cornwall; in Siberia, in Ar- menia, on the right bank of the Euphrates, and elsewhere ; in the tin-mine of Kianfu, in China ; and in Mexico. It occurs in primitive and transition mountains and in porphyry.* The other metals have scarcely yet been applied to any pur- poses of utility; and most of them are of rare occurrence. JLrt of Mining. 38. The working of mines for the purpose of extracting metallic ores, may be supposed, like several other useful arts, to have originated from accidental circumstances. It has been already stated, that some metals, and especially gold and silver, have been occasionally found on the surface of the earth, or at an inconsiderable depth beneath it ; and hence it may not unreasonably be presumed, mankind first became acquainted with the treasures of the mineral kingdom of nature. But though accident might have led to the discovery of the precious metals, which always occur in a state of purity, or else mechanically mixed with other substances, that is by no means the case with the metals in gene- ral, by far the greater number being obtained in the form of ores, consisting of sulphurets, oxides, chlorides, or metallic salts, con- stituting chemical compounds, often presenting to the inexpe- rienced eye no traces whatever of the usual characteristics of a metallic body. 39. If metals in such a state, had been commonly dispersed In what countries and in what class of rocks does nickel occur? With what metals is nickel commonly associated ? In what countries and in what situations is manganese found ? Where is chrome obtained ? arsenic ? How may we suppose the working of metals to have originated ? In what four classes of compounds does the greater number of metals occur in nature ? * Nouv. Diet. d'Hist. Natur. appliquee aux Arts, &c. Paris, torn. xxi. 1818; Art. MINE; Bake well's Introd. to Geology, chap. xix. ; and Metal- lurgie Pratique, formant paftie de la Bibliotheque Industrielle. Paris, 1827 DISCOVERY OF METALLIC ORES. 197 on the superfices of the terrestrial globe, they might forages have passed unnoticed or unappropriated, till their real nature and com- position had been developed by some fortunate accident, or ascer- tained by the slow process of observation and experiment. Some have ascribed the discovery of the nature of metallic ores, and of the method of reducing them, to the conflagration of forests on the sides of metalliferous mountains. 40. Bishop Watson says, " The most obvious method of clear- ing a country of its wood is setting it on fire; now in most mineral countries there are veins of metallic ores, which lie con- tiguous to the surface of the earth, and these having been fused whilst the woods growing over them were on fire, probably suggested to many nations the first idea of smelting ores : ' Powerful gold first raised his head, And brass and silver, and ignoble lead : When shady woods on lofty mountains grown, Felt scorching fires ; whether from thunder thrown, Or else by man's design the flames arose Whatever 'twas that gave these flames their birth, Which burnt the tow'ring trees and scorch'd the earth; Hot streams of silver, gold, and lead, and brass, As nature gave a hollow, proper place, Descended down and formed a glitt'ring mass.' 41. "There is no natural absurdity in this notion of the poet; and indeed it is confirmed by the testimony of various ancient historians, who speak of silver and other metals being melted out of the earth during the burning of the woods upon the Alps and the Pyrenees. A similar circumstance is said to have happened in Croatia, in the year 1762 ; a large mass of mixed metal, com- posed of copper, iron, tin, and silver having been fluxed during the conflagration of a wood which was accidentally set on fire."* 42. The discovery of the existence of veins of metallic ores within the bowels of the earth, whether it originated solely from the re- searches undertaken in consequence of such fortuitous circum- stances as those here specified, or from some other causes, must have led to some of the simpler processes of mining ; and the art must have been improved and extended, like other arts, by the invention of methods for overcoming occasional obstacles, and through the necessity that from time to time occurred of making experimental researches. 43. In the prosecution of such undertakings the miner must frequently be guided by appearances, on which he may perhaps be induced to rely, without being at all able to trace their con- nexion with the objects of which he is in quest. " Thus a green, To what occurrences has the discovery of the art of working metals been ascribed ? What testimony have we of the correctness of this supposition? * Chemical Essays, vol. v. R2 1 98 METALLURGY. earthy matter is a good symptom in a tin mine ; a brown, ochry earth, and compact iron pyrites, are regarded as favourable omens in a copper mine. Detatched pebbles of ore, or fragments of veinstones, have sometimes led to the riches of the vein ; and tin has especially been thus discovered in Cornwall. The miners, though a shrewd class of people, are often preyed upon by the most vulgar superstition, and many ancient absurdities are still retained and cherished in their art. The divining-rod and other oracles are yet consulted ; genii are said to preside over the mines, and he who inadvertently whistles when below ground, breaks the spirits of his companions for the day, though freely permitted to indulge in his musical disposition in the form of a song. 44. " In older mineralogical works, we read much upon these and other subjects. Flames of light have been described as playing over a district which afterwards has been found to contain subterranean riches ; and this may have arisen from the good electrical conducting powers of the vein. The waters issuing from the soil sometimes hold metallic salts in solution, and re- positories of metals have been discovered by circumstances of this kind. Copper veins tinge waters blue, and a piece of grease put into them becomes rapidly stained of that colour. There is no popular notion more common than that metals grow in the veins ; an idea which may very probably have originated from observing the depositions of one metal by the introduction of another into its solution, as when silver is precipitated by the introduction of a plate of copper into its solution, or copper by iron. 45. Districts rich in metals are generally barren, and seem pe- culiarly dreary and desolate to the traveller. This partly arises from the nature of the strata, and partly from the heaps of rubbish and hills of stone thrown upon the surface, and partly from the operations carrying on in the vicinity being inimical to vegetation. The high road through Cornwall, especially near Redruth, is an excellent specimen of this kind of country ; while, at the same time the romantic beauty and luxuriant vegetation of many parts of that county and of Devonshire, prove that exterior cultivation is not always incompatible with internal riches. The neighbour- hood of the Parys mountain, in Anglesea, is singularly marked by sterility and gloominess. The soil, naturally unproductive, is rendered more so by the poisonous waters that traverse it, and by Ihe sulphurous vapours that float around. There are not only no What exterior characters of the ground are often relied on, to indicate the presence of metallic ores beneath the surface? What superstitions are prevalent in mining districts ? What aid have the waters of a country been found to afford in judging of its mineral treasures ? What notion is entertained respecting the growth of metallic veins ? What state of soils appears to prevail in mining districts ? To what is this attributed ? By what circumstance incident to mining operations is the natural ste- rility of the soil increased ? MINING PROCESSES. 199 shrubs and trees, but the barrenness is unrelieved even by a single blade of grass, or the rusty green of a hardy lichen."* 46. The construction of works in mines must vary according tc circumstances, as the forms of hills, the position of ores in beds or viens, and the obstacles to be encountered in excavating them. Sometimes mines are formed by driving a level from the mountain to reach the vein, the contents of which may be removed through this lateral opening, in which case shafts are only required for ven- tilation. This seems to be among the simplest modes of opera- tion ; and another is, following the ore from its outlet at the sur- face as far as circumstances will allow. When regular metallic viens are found in primitive rocks, they are sometimes worked to great depths by more varied and extensive operations, being oc- casionally carried below the level of the sea. In such cases per- pendicular shafts are formed, by means of which the accumulating water is drained by machinery ; and these shafts communicate with levels driven upon the lode or vein at various depths. 47. The art of mining comprises a variety of processes, essen- tial or accessory, the most important of which are included in the following enumeration: (1.) Works of research, undertaken for the purpose of discovering metallic beds or viens. (2.) The con- struction of shafts and galleries. (3.) The tracing of the bearing, direction, and probable extent of the mineral deposits. (4.) Exca- vating the metallic ores. (5.) Works requisite for ensuring the security of the shafts and galleries ; as propping, planking, plaster- ing, walling, building arches, &c. (6.) Making air-shafts or fun- nels, and other arrangements necessary for securing a proper venti- lation, throughout the works. (7.) Methods of raising or transport- ing ores or minerals to the surface. In the mines of England and Silesia, iron railroads or canals are sometimes constructed Tor the conveyance of the mineral produce ; as in the Worsley coal-mines, in Lancashire, where subterranean canals were formed by the cele- brated Brindley, before the middle of the last century. 48. In the iron mines at Fahlun, in Sweden, and in the mines of rock-salt, in Galitzia and elsewhere, when the excavations are suf- ficiently capacious, horses are sometimes introduced to work under ground, a practice which does not appear to have been adopted in England ; though those animals were commonly employed to work machinery on the surface, before the introduction of steam-engines into the mining districts, and are still used in many situations. What is one of the simplest modes of arriving at subterranean veins of ore ? In what manner is this effected in level countries ? What is meant by the term lode in mining ? What is the first kind of labour connected with this art ? What is the second ? third ? fourth ? What kind of precautionary operations do the preceding labours require ? What works are necessary with a view to the health and comfort of the miners ? What for the removal of the products of the mine ? * Brande's Lectures on Geology, lect vi. 200 METALLURGY. (8.)"Removing or stopping out water. (9.) The accessory opera- tions of blasting rocks with gunpowder, or firing them by kindling on their surface large piles of wood, and thus causing them to split by the effect of heat, as is practised in the mines of Rammelsberg, in the Hartz ; those of Geyer and Altenberg, in Saxony ; of Fel- sobanya, in Transylvania ; of Kongsberg, in Norway ; and others. (10.) Among the most important accessory arrangements are those which relate to lighting the mines and providing against the dan- ger of explosion where the inflammable vapour called fire-damp occurs ; and to obviate this, various plans have been adopted, as the use of steel-mills, and Davy's wire gauze lamps.* 49. Any detailed notice of mining operations, though it might be rendered interesting, would be quite inconsistent with the plan of this work ; but a few particulars may be added, relative to the manner in which gold and silver mines were worked, both in Europe and America, in the seventeenth century; and also con- cerning the modes of proceeding at present among the miners in Cornwall, England. 50. At Kremnitz, in Hungary, there is a gold mine, which when it was visited by Dr. Browne, about 1680, had been worked nine hundred and fifty years. It was nine or ten English miles in length, having one horizontal passage or gallery, eight hundred fathoms in length, called the Erbstall. Its depth was above one hun- dred and seventy fathoms. "Ladders were not used to descend into the mine, but persons were let down by a cable, to which was affixed a seat of leather, affording a safe and convenient car- riage even to those who were not used to it. There were six shafts or perpendicular pits that might be entered in this manner, each having a distinct name : (1.) That of Rodolphus. (2.) Queen Anne.^3.) Ferdinand. (4.) Matthias. (5.) Windshaft. (6.) Leopold. 51. "I went down," says the traveller, "by the pit of the em- peror Rodolphus, gently descending by the turning about of a large wheel, to which the cable is fastened, one hundred and eight fathoms deep into the earth ; and after many hours being in the mine, was drawn out again by Leopold's pit, straight up, above one hundred and fifty fathoms, a height surpassing that of the pyramids by a third part. At the bottom of which pit I was not discouraged to find myself so deep in the earth, for considering I was yet above three thousand miles from the centre, f I thought myself but in a well. It is built on all sides with fir-trees, one lying upon another, (like tranverse logs,) on the four sides, from the top to the bottom. The miners work towards one, two, or three of the clock, as they speak; for they direct themselves under ground by a compass, not of thirty-two points (such as is used In what two ways is heat applied to split the rocks of mines? How is light obtained in underground operations ? What account is given by Dr. Browne of the Hungarian gold mines? * See Scientific Class Book, pt. i. p. 326 5 also, Treatise on Chem. No. 282. t Nearer four thousand miles. See Scientific Class Book, pt. i. p. 451. SILVER MINES OF POTOSI. 201 at sea,) but by one of twenty-four, which they divide as we do the hours of the day, into twice twelve."* 52. The silver mines of Potosi, in Peru, which are among the richest hitherto known, were discovered in 1545. For the more convenient working of the mines, the Spaniards dug galleries, which they call socabonos, from the foot of the mountain of Potosi, towards the west, passing through horizontally to the mine, each gallery being eight feet broad and a fathom deep, and closed with gates that might be locked, through which the silver is carried out, and where the owner of the socabon receives a fifth part. The socabon leading to the rich vein was begun in 1556, and finished in twenty-nine years, extending two hundred and fifty rods in length. The miners work by candlelight, both day and night, by turns : those that work in the day sleeping in the night, and those that work in the night sleeping in the day. 53. The ore, which is as hard as a stone, is cut out with pick- axes, beaten in pieces with an iron crow, and carried by the miners, upon their backs, up ladders made of leather. Each ladder has three leathern ropes, about the thickness of a cable, stretched out by %ticks, so that one labourer may go up on one side, while another comes down on the other. Each ladder being ten fathoms in length, has its respective floor, on which the labourers rest during their ascent; the number of the floors differing according to the depth of the mine. The men carry the ore in bags fastened before their breasts, and passing over their shoulders behind their backs ; going up three and three together, the foremost with a lighted candle tied to his thumb, so that both hands are at liberty. Thus loaded they scramble up and down one hundred and fifty fa- thoms; exposed, besides other perils, to the danger of destruction from the falling in of the mines, or of part of the sides of the ill-con- structed pits or shafts. They suffer also from the cold temperature of these subterranean passages. The silver runs for the most part between two rocks, as in a long channel ; one side being as hard as flint aud the other much softer. f 54. This defective and laborious method of working the mines in South America, seems to have been retained till the foundation, of independent states in that part of the new world, on the ruins of the long misgoverned Spanish colonies. The improvements which have taken place, however, have been chiefly, if not entirely, owing to the investment of British property in the mines of Peru.- VVhat is meant by working towards " one two or three o'clock, &c. ? How early were the Peruvian silver mines discovered ? In what manner are these mines approached ? What is the consistency of the ore of Potosi ? In what manner is it removed ? How long was the old South American system of mining retained ? * Sir Thomas Pope Blount's Natural History, pp. 229 231 ; from Tra- vel's in Hungaria, &c., by Edw. Browne, M. D. t Sir T. P. Blount's Natural History, pp. 242244, 202 METALLURGY. Fifteen or sixteen years since steam-engines were sent from En- gland, which were used in working the shallow mines of Pasco; and as Mr. Phillips observed, "It may be assumed that the supe- rior skill of the 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 accomplish much more than could be performed by systems so rude, if system it could be called, where no regu- larity existed in the underground workings."* 55. The principal mining districts in South Britain, whence metals are procured, are in Cumberland, Lancashire, Derbyshire, North Wales, and Cornwall. Those parts of the north of England, in which lead is chiefly found, are more mountainous than the metalliferous tracts in Cornwall, and the mines in general are in elevated situations; and not being very deep, the water may be readily discharged by cutting a passage or adit, through which it may flow into the valleys, and thence to the sea. Hence steam- engines are but little needed, and a very great expense is saved. But in the mining districts of Cornwall steam-engines, and some of enormous power, are constantly used ; the water-wheels being comparatively few. The mining tracts are but little elevated, seldom exceeding 500 feet above the level of the sea ; and the streams of water are but inconsiderable in point of dimensions or power. 56. In Cornwall, it has been observed, that the difficulty is not where to find a vein, but where to find a good one. A good neighbourhood; a fine gossan (a loose, friable, ochreous substance, 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 depth, on cutting the lode, the mine is inundated with water, these are symptoms of encou- ragement for the miner, even if little or no copper ore should appear near the surface. Having selected the vein he means to work, and secured the right of working it, by obtaining a lease of the mine for a term of years, it is necessary to determine what part of the vein to begin upon, which, however, is often decided by convenience, or the facility of bringing up to it an adit from the lowest ground within the settled limits. 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 seldom continued in this direction, but is in general carried down vertically. To what may we look for improvements on that system in ihe future operations in the mines of that country ? How are mines in the North of England freed from water ? Why may not the same plan be adopted in the Cornish mines ? What disadvantage is felt by mining districts near the level of the sea ? What exterior indications encourage the miners to hope for rich veins of copper ? * Outlines of Mineralogy and Geology, 4th edit. p. 196. CORNISH MINES. 203 57. Thus if a copper lode or vein runs east and west through a hill, the adit is driven from near the base of the hill to the lode underlying north, and through it to the shaft, which is perpen- dicular. The place of the shaft on the surface is to be determin- ed 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. When the miner wishes to examine the lode above the level of the adit, he forms a cross-cut or passage from the shaft to the lode, and in the same manner other cross-cuts may be made be- low the adit, running parallel with it, and extending to the lode. In either case he may be incommoded by water, and conse- quently it will now be necessary to erect machinery near the mouth of the shaft, for the purpose of raising and discharging the water ; and it will also serve to raise the ore, as well as any rub- bish which requires removal from below. 58. Thus the miner may continue to explore the lode, to such a depth as he thinks proper, or as far as he can conveniently. Should he perceive indications of a rich lode, however, instead ol making more cross-cuts, he will probably be induced to extend his working horizontally in the lode itself, as far as may be. desirable in either direction, examining it thus in several places, and hollowing out as he proceeds those passages in the mine which he terms levels. As the cross-cuts are generally ten fathoms apart, he describes the place in which his work is pro- ceeding, in raising ore, for instance, by. saying that it comes from the ten or twenty fathom level going east or west from such a shaft, each shaft having its own designation ; but only such levels are reckoned as are below the adit. 59. In sinking the shaft, or driving the cross-cut, or ex tending on the lode, the miner sometimes finds that he is in want of air; not that the fire-damp occurs, as in some coal- mines, causing so many fatal accidents ; but that the vital Sart of it is so nearly consumed, that the very candle burns imly ; and this would be a sufficient indication to the miner, even if his own breathing were not affected by it. This want of air, however, is rarely felt when there are in the mine several shafts connected by underground workings ; and when it does happen, a supply of atmospheric air is obtained by means of a pipe or trunk of wood or metal, extending from about six feet above of the surface to the lowest part of the workings, or to such a place as may be most convenient, and having on the top a wooden box turned to the wind ; and there is a more effectual mode, which consists in placing on the top of a pipe, the upper part of which is of iron, a small stove or grate, containing coal, inclosed in such a manner that the fire can only be supported by drawing its supplies of air How is the inclination or underlie of a metallic vein determined? How are adits dug with reference to the underlie of the lode? What is meant by " levels" in the working of a mine ? By what devices is the want of fresh air supplied ? What, besides the difficulty of breathing, apprizes the miner that the air is becoming impure ? 204 METALLURGY. from the bottom of the working ; and thus the foul air passes up the pipe, and a constant current is kept up ; the candle then re- sumes its splendour, which, however, is but feeble at the best, and the miner breathes more freely. 60. If the quantity of water which enters the mine be so great that it cannot be discharged fast enough by a horse-wheel and buckets, and circumstances do not admit of the erection of ?. water- wheel sufficiently powerful, the only resort is a steam-engine. Two large steam-engines are not uncommonly employed in 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 to place it, have cost more than forty-five thousand dollars. The miner does not calculate the power of his engine with reference to horse-power, but by the diameter of the cylinder. The cylinders of the largest engines in Cornwall are 91 inches in diameter. There are two of 90 inches on " the Con- solidated mines. 61. As an extreme 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 the largest and the deepest shafts in the mine. An ordinary shaft, or one which is only to contain the ladder, (for the miner always descends by the ladder, never by the rope, as in coal-mines,) is only just large enough for that single purpose ; but the engine shaft, as it is termed, is ge- nerally large enough to admit of two divisions, one for the pumps, and another for the bucket or kibble, and sometimes a third division as a footway or ladder ; and the bottom of this shaft is generally 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 underground work- ings connected with it, and the incessant drainage into it from the country or rock, in which the mine is situated. But besides being employed in discharging the water of a mine, the steam- engine is sometimes used for the raising of ores, which it does with a rapidity far greater than can be attained by any other means ; sometimes, however, very small engines, termed steam- whims, are erected for this purpose alone, in such mines as are very rich.* To what are miners compelled to resort in cases where great quantities of water enter the mine ? What remarkable instance of interference from water in mines has been experienced ? In what situations are the engines for discharging water commonly placed ? What is meant by the sump of a mine ? What by the kibble ? What name is given to the engines which raise only ore from a mine ? * See Philips's Outlines, p. 198, &c. SECTION OF A MINE. 205 62. Dolcoath mine, 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 in Cornwall, being about 250 fathoms from the surface to the sump. This mine has been working above fifty years, and is still rich, and its underground workings are very extensive. The copper mine of Ecton, in Staffordshire, is now worked at the depth of 472 yards, being the deepest in England. The deepest mine in Europe, or in the world, is said to be that of Truttenberg, in Bohemia, which is worked 1000 yards below the surface. 63. The preceding section of an extensive mine will serve to give the reader some notion of the forms and directions of the What are the depths of some of the deepest mines in Europe ? Draw and explain the section of a mine. S 206 METALLURGY. shafts, galleries, or cross-cuts, and other works requisite for the extraction of the ores of metals from the bowels of the earth. A. Principal shaft, for raising water and ores : this pit commu- nicates above with a horse-wheel, and lower down with the adit F, and inferior galleries or cross-cuts. B. Water-wheel to work pumps or other machinery in the adit or gallery F. C. Large air-shaft, communicating with the lowest gallery, D. D. Shafts of communication between the galleries. E. E, E, E. Galleries at different depths, in the line of the vein or lode, for the extraction of ores or water. F. Principal gallery, or adit, for the discharge of water raised into it by pumps, or descending from works in the higher part of the mountain in which the mine is situated. G. Horizontal wheel, (worked by horses,) round barrels fixed to the axis of which pass ropes, extending over pulleys, and de- scending into the shaft A. H. Large shaft traversing the lode, extending from the surface to the bottom of the mine, and serving for the descent of miners, and as an air-shaft. Stages or floors are placed in it at short dis- tances, to lessen the danger of accidents. (34. Such are the usual arrangements adopted for the works of mines, in most situations, and under favourable circumstances. In particular cases, however, additional constructions are required for the prosecution of such undertakings. The galleries of some mines are extended under the bed of the sea, when of course especial attention must be paid to the support of the roof of the mine. 65. Perhaps the most remarkable work of this description was a mine opened more than a century ago, in the midst of the sea, nea the port of Penzance. At low water in this place a gravelly bottom was left bare, in which appeared a multitude of small veins of tin ore, crossing each other in every direction. The sub- jacent strata also contained this mineral in considerable quanti- ties ; and works were carried on in the rock whenever the sea, the time, and the season would permit, until the depth became too great. 66. The place where this submarine tin ore was found was about two hundred yards from the shore ; and the bank of the sea here being very steep and high, the distance is considerable, even at low water ; and at high tide the rock is covered by three fathoms of water. As the bottom is gravelly and full of rocks, the waves become much agitated, and rise to a great height when the wiijd blows from particular points. This inconvenience takes place throughout the winter, and had always led to the failure of differ- ent attempts which had been made before to drain the mine and What peculiar precautions are required in submarine mining ? What instance of this is particularly worthy of notice ? What depth of water was sometimes found over the Penzance mine? WHEAL FERRY. 207 raise the ore. At low water-mark, the rock appears a little above the surface of the sea ; but during some months of the year it is never uncovered. 67. Against all these difficulties a single individual, whose property was not worth three crowns, and who undertook the work anew, had to contend. This courageous miner employed three summers in sinking a pit, during which time he could only work two hours a day, and every time he went to work he found his excavation full of water, which he was obliged to empty out before he could recommence working; and this occasioned great difficulties when he set about blasting the rock. He therefore built round the mouth of the pit a turret of wood impervious to water, or a sort of coffer-dam, and by this means was able to pro- long the time of working on the rock. And by raising the turret above the greatest height to which the sea could reach, he endea- voured to keep out the water entirely. 68. But here he had new difficulties to encounter : first to make the turret water-tight; and secondly, to secure it in such a manner that neither the flux nor reflux of the sea, or the shocks of the waves, should overturn it. The rock was, fortunately, of por- phyry ; not too hard to cut, but still very firm. He shaped the portions he separated from it, a,nd disposed them in a regular manner at the foot of the turret, and closed and caulked with oakum and fat cement all the interstices between the wood and the stone, so that the whole was united into one mass. The pit, like all those in Cornwall, was lined with planks, all the joints being well caulked or pitched. When this frame-work was thus constructed, he supported it with iron braces. About the mouth of the pit he raised, upon four great piles, a platform of planks, to support the windlass, which was worked by four men. When with great labour and difficulty the pit and tower were finished, he then reaped the fruits of his industry, and establishing a re- gular work at Stockvvork, he drew from it in a little time a consi- derable quantity of tin, and put his adventure on a good footing. 69. There were times, however, when his undertaking was not in so good a state. To save expense and diminish his labours, he at- tacked the part of the mine overhead, by which means, at high water, the sea penetrated through the chinks of the rock, so that he was obliged to sustain the roof, which was pretty extensive, in some parts by planks and thick props, to prevent the great mass of water which pressed on it above from driving it in. Besides this, notwithstanding all his endeavours, it was not possible to Jkeep his wood-work water-tight in the winter, and when the sea was rough, he could not transport the ore ashore in his boat. In What expedient enabled the miner to obviate the difficulty arising from tho water ? What device enabled him to raise the mineral from his submarine pit ? What difficulty arises from the hydrostatic pressure in excavations un- ier the ocean ? 208 METALLURGY. the autumn of 1790, the chamber excavated in the inside of the rock had the following dimensions : Greatest depth 36 feet. Depth to the level of the passage - 26 feet. Greatest diameter of the chamber - 18 feet. Least diameter - 3 feet. 70. Four men in two hours emptied the pit of water by the ^windlass, at the rate of four tons in a minute, towards the end of which time, six men drove it from the bottom of the pit, and poured it into the passage. After drawing out the water, they worked six hours on the rock. From one tide to another, they raised about thirty sacks of ore, each sack containing fourteen gallons, fifteen-sixteenths of which were so rich, that they pro- duced one-sixth of a hundredweight of tin, and one-sixteenth of a hundredweight was procured from the remainder : so that in six months they raised to the value of 600/. sterling of tin. As most of the ore was interspersed in a hard rock, difficult to pound, the undertaker had it roasted in a common lime-kiln, which answeied perfectly well. There had been nothing of the kind done in Corn- wall before. This singular work was known by the name of Wheal Ferry; the persevering individual who planned and exe- cuted it, died at the age of seventy years, in the winter of 1791, the mine having in the preceding year yielded ore worth 3000/. The works thus ingeniously constructed, were subsequently de- stroyed by accident, and the mine was ruined.* 71. In and on every extensive mine, from one thousand to fif- teen hundred men, women, and children are employed. The men and the elder boys alone descend the mines and work under- ground ; the women break in pieces the ore with hammers, and the children pick and sort it. The best ores are at once broken small by the double-handed hammer,-and put to pile, being in that state merchantable ; the inferior ores are broken by single-handed ham- mers, and sorted, the poorest are committed to the stamps, which are piles or heavy beams of wood, shod with iron, and tilted, or raised and let down alternately, by means of an axle turned by a water-wheel ; and thus the ore is bruised so fine, that the whole mass has, after being washed, the appearance of slime, and in this condition it is sold.f How extensively was the Penzance mine excavated? What was the ultimate success of the Wheal Ferry ? What number of persons are commonly employed in Cornwall about a single mine ? How are the several classes of persons respectively engaged ? Describe the several modes of levigating the ores of copper. * Dr. Lardner's Treatise on the Progressive Improvement and Present Stale of the Manufactures in Metals, vol. iii. pp. 15 17. t Phillips's Outlines, pp, 207. 208. MECHANICAL ASSAYS. 209 72. The copper ores of Cornwall are not smelted in the county, in which coal is not found, but are shipped, generally at the port nearest to the mine, for Swansea, in the vicinity of which the principal smelting companies have their establishments. Formerly there were one or two companies which smelted in Cornwall, but it seems to be found by experience to be less expensive to carry the ore to the 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 railroad ; and, in return, coal is brought to the mine, shipped from Wales, in vessels which take back copper ore. Docimasy. 73. The art of assaying minerals, for the purpose of ascertain- ing their composition, and especially the nature and proportions of their metallic products, is termed docimasy, or docimastics. It differs from metallurgy in its strictest acceptation, in that the requisite operations of docimasy are performed on a small scale, and without any attention to those economical considerations which are of so much importance in the processes of the metallurgist. 7-1. The great object of assaying a mineral, is to form an ac- curate estimate of its component parts and their relative propor- tions, and thus to discover whether it is rich enough in metal to pay the expenses of working a mine, and reducing the ore to the metallic state. These preparatory operations are peculiarly re- quisite, with regard to minerals or mineral products containing the precious metals, because a knowledge of the exact quantity of metal in any substance, especially if the quantity be comparatively small, must be obtained before it can be possible to decide whether it will be worth while to undertake its extraction. 75. There are three modes of conducting docimastic operations : (1.) The mechanical assay; (2.) The assay by the dry method ; (3.) The wet assay. Mechanical Assays. 76. Processes of this nature merely consist in the separation of substances mechanically mixed in metallic ores, and are executed by sifting, washing, and thus removing the soluble and lighter portions of the substance to be examined, so that the metallic particles may be obtained in a separate state. To make an assay by the mechanical method, the ore having been pulverized, a cer- tain quantity of it, by weight, is to be put in a sieve with a little water, and then, by agitation, the lighter matters may be separated from the metallic particles, in consequence of their superior specific In what manner do the Cornish miners dispose of their ore when ex- tracted ? How does doeimasy differ from metallurgy ? What is the great purpose of assaying minerals? In how many different modes are assays conducted ? How are mechanical assays performed ? s2 210 METALLURGY. gravity. Thus a moist mass, or scfilich, more or less pure, will be obtained, from which a judgment may be formed of the quality of the ore, and from this mass the whole of the metal may be ex- tracted by assaying it, either in the dry or in the wet method. 77. Washing is practised as a method of assaying auriferous and stanniferous sands, or with regard to schlichs, which have been already washed, to ascertain the degree of purity to which they have been reduced. This mode of assay may be also advan- tageously employed to separate the oxide of tin, and the sulphurets of lead and antimony, from the gangues or stony matter in which these ores are frequently disseminated. The same kind of assay may be properly used to discover whether scoriae, or other products of the furnace, retain enough metallic matter to make it worth while to treat them on a large scale by stamping and washing.* by the Dry Method. 78. The dry mode of assay has for its object the discovery of the nature and quantity of the metals contained in any ore ; but to prevent needless experiments, it is desirable to be able to decide beforehand what metal may be supposed to exist in a fragment of an ore about to be submitted to examination. To obtain this previous information, attention should be paid to mineralogical characters, which will often afford positive indications of the nature of the mineral ; but when there is any room for doubt, it becomes necessary to vary the mode of inquiry, and submit the substance to a twofold operation. Thus the mineral fragment to be assayed is to be divided into two portions, one of which may be analyzed with a view to discover the precise nature of the metal, and the other to determine its proportion relatively to the other substances with which it is mixed. 79. Assays by the dry method require great skill in the operator, and but an inconsiderable apparatus. They may be performed generally in workshops, and they become peculiarly necessary in those where ores are purchased fronr different localities ; because, when the quantity of metal they afford can be ascertained, it be- comes easy to fix the price that must be given for the ores. These assays are performed by submitting the mineral body to the action of fire, either by means of cupels, retorts, matrasses, crucibles, or by the blowpipe. It is frequently requisite in these operations to add a flux, or some other substance which may facilitate the de- composition of the ore. What is meant by the term schlich in mechanical assaying ? Under what different circumstances may the method of washing be adopted ? What is the object of assaying by the dry method 1 What two purposes are to be answered by this method ? What are the requisites for prosecuting this mode of assaying? In what way are its processes executed ? * Metallurgie Pratique, pp. 33, 34. USE OF THE BLOWPIPE. 211 80. The blowpipe is peculiarly useful in conducting assays, in consequence of its ready application, without loss of time or trouble, as it affords a simple and convenient method of heating to a high degree, very quickly, any substance sufficiently small to be involved in the flame excited by this instrument. There are a variety of forms of the blowpipe, among the most convenient of which are those of Dr. Wollaston, described by Mr. Brande,* and that of the Swedish chemist, Gahn. This blowpipe is com- posed of four tubes : (1.) The principal tube or mouthpiece of the blowpipe ; (2.) A cylindrical chamber to collect the water formed from condensation of the moisture of the breath : (3.) The beak, at the extremity of which is, (4.) The jet-pipe, through which the air escapes. The jet may be formed with an opening more or less minute, to suit particular purposes. This blowpipe, when taken to pieces, may be fitted into a box or case, adapted to the pocket, so that it may be ready for use in any situation. d' The accompanying figure represents this blowpipe, a is the main tube, to which is sometimes adapted an ivory mouthpiece, e, to avoid the contact of metal with the lips, b is the flat cylin- drical box, from the convex side of which projects the short tube o, to receive the end of a. In one of the flat sides of the box is fitted, with a swivel joint, the beak c, with its jet-pipe c?, canaMe of revolving into any position as indicated by d' ' . 81. In employing this instrument, it must be held in the hand with, the larger end of the tube introduced between the lips; then the beak of the jet being approached to the flame of a wax candle, or that of a lamp, with a wick of a proper size, on blowing through the pipe the flame will be projected upon the substance to be" assayed. A large wax candle will be found to supply the best flame, w^iich, when urged by the blast, exhibits a double figure, the internal flame being conical, blue, and well defined, and at its apex the most intense heat is excited ; the external flame, encom- passing the other, is red, vague, and undetermined, and much infe/rior in temperature. 82. Some attention is necessary to acquire the habit of properly using the blowpipe, so as to throw the flame regularly and unin- What circumstances render the blowpipe peculiarly serviceable for this purpose ? Of what parts do ihe most approved blowpipes consist? In what manner is this instrument to be used ? * See Webster's Manuel, on the Basis of Brando's. 212 METALLURGY. terruptedly on the body to be examined, and also to continue the blast during a sufficient time without fatigue and exhaustion. This object may be attained by first filling the mouth with air, which is to be driven through the tube by the pressure of the muscles of the cheeks alone, those of the chest not at all contribut- ing to the keeping up of the blast. To renew the air in the mouth it is necessary to respire only through the nostrils, which may be done without discontinuing the blast, and thus a person may con- tinue blowing a long time without inconvenience. 83. The substance to be submitted to the action of the blow- pipe, should not be larger than a peppercorn, and it may be placed on the extremity of a slip of platina, or held in a pair of pincers of that metal, or else laid in a small cavity on the surface of a piece of charcoal. In the latter case the charcoal should not be that of fir, or any other wood which would be liable to sparkle in burning, and the cavity in which the mineral is laid may be covered with another piece of charcoal, only leaving an opening for the access of the flame. In most cases, instead of exposing the mineral merely to the action of the flame urged by the blow- pipe, the substance is pulverized, and mixed, either with oil or with water, and some proper flux ; and a small pellet thus being formed, is to be submitted to the flame, and it will thus be less exposed to be driven off when ihe action of the fire becomes violent. 84. When a mineral substance is heated at the extremity of the flame, on platina or charcoal, uncovered and exposed to the air, it may become oxidated; but when, on the contrary, it is heated without the contact of air, which may be done by covering it with charcoal, or projecting the flame so that it may environ the body on all sides, it will become disoxidated, either entirely or in part, if it contained oxygen. The results in either cases will conse- quently be very different, for the first is termed the fire of oxida- tion, and the second the fire of reduction. 85. When it is requisite to oxidate a metallic substance, com- bined with any flux, it must be heated intensely, and when fused, gradually withdrawn from the point of the blue flame, and the operation repeated as often as may be necessary, using a jet of large aperture. The oxidation may also be accelerated by the addition of a small quantity of nitrate of potash. In order to reduce the metallic oxides, the" glass bead formed by the sub- stance to be examined, and the flux, must be kept in fusion on charcoal as long as it remains without being absorbed, that the metallic particles may collect into a globule on the surface of the charcoal. It is then to be fused with a small quantity of subcar- How is respiration to be carried on while we use the blowpipe 1 How is the substance assayed by the blowpipe to be held ? What previous preparation of a mineral facilitates its treatment with the blowpipe ? What part of the flame is called the oxidating fre ? What part the reducing or deoxidating fire ? In what manner is a metal oxidated when combined with a flux ? How are the metallic oxides thus formed to be finally reduced ? MOIST METHOD OF ASSAYING. 213 bonate of soda, which will be absorbed by the charcoal, and the spot where the absorption has taken place must be strongly ignited, by using a tube with a small aperture. By continuing the ignition, that portion of the metal not before reduced, will be brought to the metallic state, and the process may be quickened by placing the globule on a smoky flame, so that it may become covered with soot. 86. The beads which contain metals frequently exhibit a metal- lic splendour, especially if exposed to a gentle flickering smoky flame after the intense heat has ceased. With a moderate heat the metallic surface remains, but after a little practice it may be ascertained without difficulty, whether any metal is contained in the body under examination. It should be observed that glass of borax alone sometimes assumes, externally, a metallic lustre. When the experiment is concluded, and the charcoal become cold, that part impregnated with the fused mass must be cut out and rubbed down with distilled water in an agate mortar, the soda which formed the flux will be dissolved, the charcoal will float on the liquid, and may be poured off; any of the metallic particles remaining at the bottom may then be examined. By this mode of assay most of the metals may be reduced.* Assays by the Moist Method. 87. When an ore is examined by the moist method, complicated processes sometimes become requisite, for the management of which a considerable degree of skill in chemistry must be ac- quired; but this method presents important advantages in practice. The assay of ores, by the moist mode, consists principally in exposing them to the action of acids, alkalies, or neutral salts, nd when solutions have thus been obtained, the metals may be recipitated by proper additions, and a judgment of their nature formed from the colour or other sensible properties of the precipi- tates. Thus metallic solutions may be analyzed by the applica- tion of tests, but in order to discover the relative quantities, as well as the qualities of a mineral, by the moist assay, the metals must be precipitated from their solutions, and the products edul- corated and weighed. 88. Gold may be tested by exposing it to the influence of nitric acid, which acts upon almost all other metals, but leaves the gold untouched. For what purpose is subearbonate of soda employed in this operation? Of what does assaying by the moist method consist? How are the actual quantities of different ingredients in a mineral de- termined ? How is the presence of gold ascertained ? * For particular information relative to the analysis of Alloys by Cupel- lation, see Children's Essay on Chemical Analysis, pp. 96108 ; and for the methods of making exact assays of the more important metals, see Metallurgie Pratique, pp. 3966. 214 METALLURGY. Silver ore may be assayed by reducing a small quantity of it to fine powder, digesting it in nitric acid, and mixing the filtered liquid with a solution of common salt, (chloride of sodium.) A chloride of silver will then be precipitated, containing, when dried, 75 per cent, of metal ; or the chloride may be reduced by fusing it with three times its weight of subcarbonate of soda.* 89. Iron ore is sometimes treated in the moist way, in order to discover whether it contains phosphorus, which would destroy the malleability of the metal. In this case the ore supposed to con- tain phosphorus must be mixed with one-fourth of its weight of nitrate of potash, and placed in an earthen crucible, which is to be strongly heated for half an hour; then the mixture, being with- drawn from the crucible, must be lixiviated with airmail quantity of distilled water and filtered : the liquor obtained is now to be assayed by the following process : After it has been neutralized by nitric acid, a solution of chloride of lime is to be poured over it, and the liquor will not become clouded unless a small portion of carbonate of lime should be formed, which must be separated by filtration ; then a little ammonia must be added, and if a white precipitate is formed in consequence of this addition, it will be a proof that the ore contained phosphorus, the white precipitate being phosphate of lime. 90. The analysis of copper ore by the moist method is effected by treating the roasted mineral with nitric acid ; and by adding ammonia in excess, the oxide of copper will be dissolved, and the other metallic oxides partly precipitated ; then the alkaline solu- tion of the metal, after being filtered, is to be saturated by an acid, and the copper may be precipitated in the metallic state, by plates of polished iron. 91. The moist method of assay may be employed in analyzing the ores of lead, and the products of the foundries. The roasted ores must be dissolved in nitric acid somewhat lowered, and the solution is to be diluted with water, and precipitated by a suffi- cient quantity of some soluble sulphate, which forms with the oxide of lead, sulphate of lead. The precipitate being washed and dried, always contains sixty-eight per cent, of metal. In thi$ How may silver ore be assayed ? For what purpose is iron assayed in the moist way ? How is the assay then conducted ? What substance is added to test the presence of the phosphoric acid ? How is the assay of copper in the moist way to be conducted ? How is lead ore examined in the humid way ? How is the quantity of lead which it contained finally discovered ? , * Report of Brande's Left, on Mineralog. Chemistry, in Jour, of Science, vol. iy. p. 245. A convenient method of producing chloride of silver is mentioned in Annales de Chimie, t. xiv. p. 319. Put the chloride into a small vessel of zinc or cast iron, containing a little water; and leaving it there a short time, if the vessel be clean, the decomposition will soon take place, otherwise a little muriatic or sulphuric acid may be added. Tho metallic product may be washed with muriatic acid. METALLURGY PROCESSES. 215 mode of assay the silver which may be contained in the ore will also be precipitated in the state of sulphate. When it is neces- sary to assay sulphates of lead, either alone, or mixed with other substances, the muriatic must be employed instead of the nitric acid.* 92. Solutions of the various metals may be tested, and their nature ascertained to a certain extent, by observing the effects of the addition of certain bodies called reagents, and noting the colours and other sensible properties of the precipitates thence produced. Thus tincture of nutgalls turns the solution of iron black, and the solution of lead white, and with other metallic so- lutions, yields green, yellow, brown, or blue precipitates. f Metallurgic Processes for the Reduction of Mineralized Metals 93. The operations requisite for obtaining metals in a pure state from their several ores constitute the proper subject of me- tallurgy. The methods adopted for the reduction of metals, must necessarily be varied according to the nature of the metal to be obtained in any given case, and that of the substances with which it may happen to be blended. Hence a diversity of processes will be required even with regard to a single metal. They may, how- ever all be referred to three kinds, like those of docimasy, con- sisting of mechanical operations, in the dry way, or by means of fire, and operations in the moist way, chiefly by employing mineral acids. But in almost all processes for obtaining metals from their ores, the mechanical and chemical methods are more or less combined according to circumstances. 94. Metallurgic chemistry includes the art of forming com- pound metals, or alloys, some of which are more serviceable for certain purposes than any of the simple metals. This branch of knowledge it will be percived, affords an extensive field for re- search,presentingto our notice many subjects extremely interesting, not only to artists and men of science, but especially to all persons engaged in the study of mineralogy and geology. In the few re- maining pages to be devoted to metallurgy, nothing more can be attempted than the introduction of some general notices of the processes employed in the reduction and refining of the principal metals, and in the formation of the most useful alloys", such chiefly being selected as may tend to show the connexion between the How are sulphates of lead and of other materials tried ? v By what sensible properties are metallic ores often judged ? What constitutes the peculiar provincce of metallurgy ? Of how many kinds are the processes employed in this art ? What does metallurgy include besides the reduction of ores ? * Metallurgie Pratique, pp. 47, 51, 59. t In Dr. Henry's Elements of Chemistry, vol. ii., is given a table of pre- cipitates thrown down from metallic solutions by the following reagents ; (1.) Prussiated alkalies ; (2.) Tincture of galls ; (3.) Water impregnated with sulphuretted hydrogen ; (4.) Hydrosulphurets. 216 METALLURGY. subject before us, and the other branches of science to which this volume relates. Reduction of Ores containing Gold. 95. As gold is not found mineralized, or in the state of proper ore, but either pure, or else combined with some other metal to form an alloy, the metallurgic processes for reducing it are in general less complicated than in most other cases. This metal is derived from two sources, being either mixed with sand, gravel, and earthy matter, in valleys, ravines, and the beds of rivers, or occurring in veins, and procured by mining, like metals in general. The modes of treatment requisite to procure gold in a state of purity, vary according to the state in which it is found in the situations just mentioned. 96.. Gold obtained from alluvial soils in pellets or grains, may be separated more or less from the substances by which it is con- taminated by washing. This operation is performed frequently on the spot where it is procured. Thus the gold seekers some- times wash the auriferous sands in a sieve held in the hand ; or else use inclined tables, which being covered with coarse woollen cloth or rough hairy hides of animals, the earth and sand taken up in small quantities is thrown on the table, over which a stream of water being poured or conducted, the lighter substances are wash- ed away, and the particles of gold detained by their superior weight on the surface of the cloth or skin. But this method has the inconvenience of not separating the heavier portions of gravel which become entangled among the hair or wool, together with the metal. The gold thus obtained may be further purified, ac- cording to circumstances, by amalgamation with mercury, or by cupellation. 97. Gold is also found pure in veins, but sometimes in a state of minute division, and so blended with other bodies, as to require various operations for its extraction. It is thus procured in Hungary, and in this case the whole contents of the vein holding small particles, or strings, or little nests of native gold, are brought to the surface, broken into small pieces, and carefully sorted ; the grains, where perceptible, being detached from the matrix, which is chiefly quartz. The poorer parts are then stamped, by means of wood shod with iron at the lower ex- tremity, worked b^a water-wheel, and thus the ore is crushed to a powder upon an iron plate. This powder is damped by throw- ing water containing salt upon it; and a quantity of mercury be- ing put into a bag of porous leather, is forced through the pores, and dropping on the damped powder in a minutely divided state, is kneaded up with it. In what two states is gold found in nature ? By what process is gold from alluvial soils separated ? By what methods are the auriferous soils washed ? In what rock do veins and masses of gold most frequently occur? REDUCTION OF GOLD. 217 98. The paste containing mercury and gold thus incorporated, is afterwards 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 only the amalgam of mercury and gold. Part of the mercury is then separated, by pressure, in a leathern bag, and the rest is driven off by distillation, leaving behind the gold, and also any portion of silver with which it may be alloyed. 99. When gold occurs in a matrix, consisting of iron pyrites, galena, &c., in which the gold exists in invisible particles, the masses of ore are broken by hand into small pieces, and then placed beneath the stamps to be reduced to powder, which is car- ried by a stream of water to a series of pits, in which the heaviest particles subside, the lighter earthy matter being carried away by the current. After repeated washings, the metallic parts, consist- ing principally of pyrites and galena, are roasted in a reverberator^- furnace, with a proportion of quicklime, 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. 100. During the fusion, the iron, on account of its strong 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 specific gravity, fall in drops through the vitreo-ferru- ginous scoriae, 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 portion is composed of cellular scoria?, be- neath which is a black heavy compact mass containing the gold and silver, together with lead, copper, some sulphur, and iron ; this is now broken into small pieces, and roasted and fused once or twice more, until the sulphur and other impurities are separated, leaving nothing but the gold, silver, lead, and copper. 101. The separation of gold from lead is effected by cupella- tion. The cupe'l or test is a porous, infusible, earthy mass, with a hollow concavity at the top^Sbr the reception of the metals ; this being 1 placed in a furnace, so as not to be in contact with the burning fuel, and a current of air at the same time passing over the surface of the test, the metal is brought almost to a state of ebullition. At this temperature the lead becomes changed to the state of a vitreous oxide, which, sinking into the pores of the test, leaves the gold behind ; and if the ore contained silver and cop- In what way is the amalgamation of gold conducted? How is gold treated when combined with the sulphurets of iron, cop- per,, or lead ? How are the lead and copper deprived of their sulphur ? What separates the gold and silver from the fused mass of the ingre- dients ? How is gold separated from lead ? T 218 ^ METALLURGY. per, subsequent processes will be required to effect their sepa- ration. Reduction of the Ores of Silver. 102. Silver is extracted from its ores, either by smelting in a manner similar to that practised with regard to other metals, or by amalgamation with mercury. The processes carried on at the extensive amalgamation works of Freyberg, the capital of the mining district of Saxony, and where one chief advantage of this mode over smelting, is the saving of fuel, are described with scientific minuteness by J. H. Vivian, Esq., in the annals of Philosophy, vol. xxvii. ; and an abstract of this descriptive state- ment may be found in the third volume of Dr. Lardner's Treatise on Manufactures in Metals. 103. Silver like gold frequently requires to be subjected to the JP^ocess of cupellation, to separate it from oxidizable metals. This method of purifying silver is adopted in Persia, and the following account of it is given by Ostad Muhammed Ali, and was published in Brande's Journal of Science : 104. Persian metallurgical process for the purification of sil- ver. A sort of basin is made, either by excavating the ground, or by arranging stones in a circle. This is from nine to twelve or fourteen inches wide, and is incomplete at the side in one place, for the reception of the fuel, which by its combustion is to melt the metal. The fuel consists of two large and long logs of wood, which are placed with their ends in the aperture on the edge of the basin. These ends are lighted by placing on them burning fuel, and then the blast from a pair of bellows is directed so as to pass across the fire, and thus drive the flame and heat into the basin, acting as a large blowpipe. Lead containing silver, or impure silver with the addition of lead, is then placed in the basin, and being soon melted and heated by the flame, it is puri- fied as by common cupellation. The litharge (vitrified oxide of lead) is forced off to the sides as it is formed, and either absorbed or lost, and as the wood burns away before the blast of air, the logs are thrust onward until all is consumed ; then fresh logs are supplied, if necessary, or the process stopped, as may be found convenient. * 105. "The singular fact has been ascertained, that silver in fusion absorbs oxygen, which, on solidifying, it parts with; and Gay Lussac says that it thus gives out twenty-two times its own volume, and that the presence of a very little copper destroys this property."* To what process is silver subjected in order to separate it from other metals ? Describe the Persian method of purifying silver. What fact in regard to the affinity of silver for oxygen has been ob- served ? * Donovan's Treatise on Chemistry, p. 241. REDUCTION OF CRUDE PLATINA. 219 The attraction of both silver and copper, when in fusion, for oxygen, was observed several years since by Mr. S. Lucas, of Sheffield, who stated the result of his observations in a letter to Mr. Dalton, published in the Manchester Transactions. He found that silver, in a fluid state, absorbed oxygen, not only from the atmosphere, but also from other bodies which gave it out when heated, as some of the nitrates. 100. If silver in large quantities, after being exposed, when melted, to a current of oxygen gas, or atmospheric air, be allowed to cool gradually, the surface first becomes solid, then soon bursts, ebullition ensues, and an elastic fluid escapes, driving before it a portion of the internal fluid metal, and causing protuberances on its surface. Substances which have a strong attraction for oxy- gen, placed in contact with the melted metal, prevent the ebullition from taking place. Thus charcoal, spread for a few minutes on the surface of the silver in fusion, absorbs the oxygen which it may have acquired, and no escape of gas or appearance of ebul- lition then occurs, whether the metal be cooled slowly or hastily.* Reduction of Crude Plafina. 107. Platina is never mineralized, but it is often debased by intermixture with other metals ; and in the state in \vhich it is imported from South America, the crude metal contains silica, mercury, gold, palladium, rhodium, iridium, osmium, iron, cop- per, and lead, as well as platina. This last metal may be sepa- rated from the other bodies by the following process : The mercury is to be driven off by exposing the ore to a considerable degree of heat, an operation which renders the platina yellower, in consequence of the appearance of grains of gold. The residue may be digested in nitro-muriatic acid, diluted with its bulk of water ; this takes up gold, iron, and a little platina : if the re- maining ore be now digested*in nitro-muriatic acid, by far the largest portion will be dissolved, and there will remain a black powder ; to the nitro-muriatic solution add a solution of muriate of ammonia, which will occasion the precipitation of the greater part of the platina in the state of a very difficultly soluble ammo- nia-muriate, and which may be separated upon a filter. 108. In the filtrated liquor immerse a plate of zinc, which will throw down lead, rhodium, palladium, and a portion of platina; the lead may be separated by very dilute nitric acid : dissolve the residue in nitro-muriatic acid, add common salt, and evaporate to What occurs when a considerable mass of silver is heated in contact with oxygen ? What prevents the occurrence of this phgnomer.on ? In what state is platina found ? By what means is it separated from mercury ? How is the platina next treated ? How may the nilro-muriate of platina be decomposed? * Journ. of Science, vol. iv. pp. 169, 170. 220 METALLURGY. dryness; this residue, composed of the soda-muriates of platina, palladium, and rhodium, is to be digested in alcohol, which dis- solves the triple salts of platina and palladium, but not that of rho- dium, which therefore is thus separated : to the alcoholic solution add solution of muriate of ammonia, which throws down ihe platina and leaves the palladium in solution, which may after- wards be precipitated by ferrocyanate of potassa. The insoluble black powder, by alternate fusions with potassa, and boiling in muriatic acid, may be resolved into osmium, soluble in the alkali, and iridium in the acid. 109. The yellow precipitates formed by the addition of muriate of ammonia to the alcoholic solution of the salts of platina and palladium, consisting of ammonia-muriate of platina, must then be collected, edulcorated with warm water, and dried. It must next be distributed into saucers, which are to be introduced into a small oven, and exposed for a short time to a low red heat, in order to drive off, by sublimation, the greater part of the muriated ammonia. When withdrawn it. will form a spongy mass of a gray colour. About half an ounce of the platina in this state is to be put into a strong iron mould, about %$ inches long by 1^ wide, and is to be compressed as forcibly as possible by striking with a mallet upon a wooden pestle, cut so as accurately to fit the mould; 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 adapted to fit into 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 the metal. This is an important part of the process ; for if any quantity of air is left in the mass, the bar into which it is formed will be liable, 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 hard* compact parallelepiped. 110. It is now to be placed in a charcoal forge fire, and exposed .to the most intense white heat, in order completely to drive off the remaining ammoniacal muriate ; this being done, it is to be quickly placed on a clear, bright anvil, and gently hammered in all directions with a clean hammer. This must be repeated several times ; after which the mass will be perfectly compact, and fit to be laminated or wrought in any other manner that may be required. Reduction of the Ores of Mercury. 111. The metallurgic treatment of mercury is very simple, and the metal is extracted chiefly by two methods. The following is the process adopted in the Palatinate. The ore is to be sorted, For what purpose is alcohol used in this assay ? How is the ammonia-muriate of platina brought to the state of spongy platina ? Does the process of melting form any part of the reduction of platina? What is the purpose of compressing the spongy mass ? REDUCTION OF THE ORES OF IRON. 221 pulverized, and mixed with quicklime or slaked lime ; and the richer it is in metal, so much greater must be the proportion of the lime. The mixture is then introduced into large cast-iron retorts, which are placed in two ranks, one above the other, in a long furnace ; and each retort is to have attached to it, without luting, a glass receiver, one third part filled with water. The fur- nace is then to be heated, at first gently, to drive off the moisture ; after which, the juncture of the vessels must be closed with tem- pered clay, and a full red heat is to be applied for seven or eight hours. The lime will combine with the sulphur contained in the mercurial ore, and the metal will be volatilized and condensed in the receiver. A different method of proceeding is practised at Almaden and at Idria, where furnaces of a peculiar construction are used, and the reduction of the metal is effected by the oxida- tion and consequent separation of the sulphur, which forms sul- phurous acid, while the mercury is sublimed, and becomes con- densed within the apparatus.* Reduction of the Ores of Iron. 112. This metal being found in a state of nature, variously combined, different processes are requisite to reduce it to the metallic state. The smelting of iron is a subject of national im- portance, and hence it has not only occupied much of the attention of writers on metallurgy, but it has likewise furnished a topic for distinct and sometimes voluminous treatises. It can here, how- ever, be but slightly noticed, as our limits will only admit of some brief and general statements of the peculiar methods of reducing this metal. Carbonaceous matter of some kind is always largely employed in smelting iron ores ; in some countries, as Sweden, charcoal is used for that purpose ; while in Great Britain, there are but few charcoal furnaces, coke being generally employed instead of it. The most abundant of the iron ores is the common ironstone, which is an impure carbonate of the metal, found in small lumps or layers in the clay which separates the beds of coal. 113. The ore is first reduced to pieces about the size of an egg, and is sometimes roasted 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 consumed. More commonly, however, the roasting is per- formed on the ground : a bed from four to eight inches in thickness of v coal is first laid down, on which is placed a layer of broken iron- stone, from eighteen inches to two feet thick ; two inches of small In how many ways is mercury reduced from its native state ? What is the purpose of employing lime in this process ? Plow is the reduction of mercury effected at Idria? What kind of matter is extensively employed in reducing iron ores ? * See Metallurgie Pratique, pp. 296--302. T2 222 METALLURGY. coal are then laid on the ore, and on this a pile of ore, diminishing in size so as to form a ridge at the top, and the whole is then covered with small coal and coal-dust. The pile is, at bottom, from thirty feet to sixty yards long, ten to sixteen feet wide, and about five feet high. The lower stratum of coal is then lighted, which, by degrees, lights the whole mass. In a few days the ironstone, when cool, becomes of a red or reddish-brown colour; and the sulphur, carbonic acid, water, and inflammable matter being driven off, it is fit for the smelter. 114. In England and Wales the furnace in which iron is smelted is upwards of forty feet high, and is built of the strongest masonry, externally of the form of a truncated four-sided pyramid, inter- nally of a peculiar figure, and lined partly by fire-bricks and partly by sandstone; and into which, when charged, air, in a high state of compression, and sometimes previously heated, is forced. This is a blast furnace, and is charged at the chimney at regular in- tervals with coke, iron ore, and limestone, in the proportion of about 4 of the first, 3 of the second, and 1 of the third by weight; and is always kept so charged to a certain height. 115. In somewhat more than forty-eight hours the whole runs down, being, however, constantly replaced by fresh materials, and the iron being melted, is suffered to flow out once in eight, ten, or twelve hours, 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 cannon and steam-engine boilers to fire-grates and common iron pots. 116. The fuel for smelting iron hitherto used in the United States, is charcoal, but few attempts having been made to intro- duce any other. The abundance of wood has thus far allowed this employment of its product ; but the vast extension recently given to the iron business, now calls for the introduction of some more economical species of combustible. The process of cok- ing is about to be carried on to considerable extent, at the iron works on the west branch of the Susquehanna river, in Pennsyl- vania, and the advantage which would result from the employ- ment of anthracite for this object, has called forth a number of ingenious attempts to adapt its action to the reduction of iron ore. In connexion with charcoal it has been used to some extent in France, but, as it seems, without any decided advantage, at least in the place where it was applied, over the fuel previously employ- ed. In England coke has long since almost entirely superseded charcoal, and within the last three or four years raw bituminous coal has in many works nearly taken the place of coke. v In what two modes is the roasting of iron ore effected ? What is the height and general construction of smelting furnaces ? What are the proportions of coke, ore, and limestone ? In what length of time is the entire charge of a high smelting furnace run out? What fuel is chiefly used for smelting iron in the United States ? What varieties of fuel have been employed in Europe ? SMELTING FURNACE. 223 117. Turf and even wood have in some instances been advan- tageously substituted for a part of the usual charge of charcoal, in a smelting furnace. The hot air blast is one of the most recent and capital improvements in the smelting process ; and the intro- duction of this, together with a change from the exclusive use of charcoal to a partial use of wood, has been found by M. Naher, at the iron works at Plons, Canton of St. Gall, Switzerland, to give decided advantages over the method previously pursued. The economy of using a hot blast with charcoal alone, was chief- ly in the diminution of the quantity of fuel required by a given weight of pig metal, being about fifteen per cent., while the ac- tion of the furnace was retarded by -J- of its original number of charges per day when using charcoal only, and fed with cold air ; but the substitution for one half the bulk of charcoal of an equal bulk of dry pine wood, not only gave more pig metal in a given time than when using charcoal alone, but increased the yield of the furnace from 1560 to 2019 Ibs. in twelve hours. 118. The hot air blast is applied by carrying the pipe from the bellows, sometimes through a hot air chamber above the top of the tunnel head of the smelting furnace, in .order to economize that part of the heat which ordinarily escapes and is lost. At other times it passes through a long hot air chamber, expressly intended for heating the air, and supplied with hot gas from furnaces of its own ; the latter arrangement is seen in the annexed figure, in which a plan of the smelting furnace at the level of the tuyeres is given. H is the hearth or receptacle for the melted iron. A A A A are the parts of the masonry of the structure. C C C are three branch pipes coming from the main bellows pipe, b b are small furnaces, placed near the termination of the respective branches. B is a larger furnace under the main pipe. W is a water regulator by which the intensity of the blast is prevented from exceeding a given amount. G is a common chimney for the escape of gas from all the air heating furnaces. What is found to be the advantage of using hot air in a blast furnace for smelting iron? What has experience proved in regard to the use of wood for the same purpose ? What is the arrangement for heating air for this purpose ? 224 METALLURGY. 119. There are several varieties of iron to be found in com- merce, the most important of which are cast iron, wrought iron, and steel. Of cast iron there are two principal kinds, called re- spectively white and gray iron. White iron is very hard and brittle, and exhibits a radiated fracture, being composed of a congeries of laminae, variously aggregated. Acids act upon it but slowly. Gray or mottled iron is softer and less brittle than white, so that it admits of being bored or turned in a lathe. The texture of the metal gives it the appearance of bundles of minute fibres. 120. Cast iron, after having been in some degree refined by fresh fusion, in contact with charcoal, is converted into wrought iron by a process called puddling. The cast iron is put into a reverberatory furnace, and when in the state effusion it is agitated, so that every part of the mass may be exposed to the air and flame. After some time the melted metal heaves, a blue flame issues from its surface, it gradually grows tough, loses its fusibility and becomes pulverulent. The fire is then increased, so that the parti- cles again agglutinate at a welding heat, and are wrought np into separate masses, which, while intensely heated, are passed suc- cessively between rollers, and a quantity of carbonaceous matter being pressed out, the metal is rendered malleable. The flattened masses cut in pieces are then placed in parcels in a reverberatory furnace, strongly heated, and again hammered or rolled out into bars. The iron is thus rendered more tough, flexible, and mal- leable, but at the same time almost infusible, and in this state it appears to be nearly pure. 121. A bar of wrought iron, when its texture is examined, dis- plays a fasciculated appearance, the fibres extending longitudi- nally, as may be perceived in a bar of wrought iron that has been torn asunder. Steel is a compound of iron and carbon, the latter in small proportion, and it is not improbable but it may also con- tain silicon. It partakes, to a certain extent, of the properties of cast iron and wrought iron, being fusible, like the former, and malleable, like the latter. When it is heated and suddenly cooled, it becomes hardened, and by proper management it may thus be variously tempered to form cutting instruments, and for other purposes. 122. When steel is kept for along time hi a state effusion, its carbon is dissipated, and it becomes reduced to the state of pure iron. Iron is converted into steel by a process termed cementation ; which consists in submitting iron with charcoal in alternate lay- ers to the action of heat in a close furnace for several days. Cast steel is prepared by melting common steel in a crucible, with a flux composed of carbonaceous and verifiable 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 How is wrought iron made ? What is steel ? How is it hardened ? How may steel be converted into malleable iron ? How is cast steel prepared ? REDUCTION OF THE ORES OF TIN. 225 of more compact grain, it is adapted for all the finest articles of cutlery. 123. Iron in the process of its conversion into steel acquires a blistered surface, and in this state it is used for some purposes under the name of blistered steel. This, when made into smaller bars and hammered, forms tilled steel,- which when broken up, heated, welded, and again drawn out into bars, forms shear steal. Reduction of the Ores of Tin. 124. The ore from which tin is procured in England is an oxide, found interspersed through some parts of the mineral veins in Cornwall, in small crystals, accompanied by masses of slate or granite, sulphurets of iron and 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, till the ore has the appearance of slime, and it 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 washings, are reduced to a state fit for the smelting-house. 125. Being still mingled with other substances, it is in this state termed black tin. This is roasted at a low red heat, in a rever- beratory furnace, to volatilize the arsenic and sulphur. It is then of an ochrey red colour, owing to the oxidation of the iron and copper. It is again washed, and the impurities separated from it; and it is then reduced by placing it in a reverberatory furnace, about seven feet long arid three and a half wide, from seven to fifteen hundred weight of the roasted ore being mixed with about one-fifth of 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 surface coating of boiling black scoriae. The furnace is then tapped, and the melted tin suffered to flow into a small cavity at the foot of the furnace. When that is done, the scoriae are raked off, and a new charge of roasted tin ore and small coal thrown in. 126. 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 What is meant by blistered steel ? What by tilted steel ? What is shear steel ? In what state is the ore of tin found ? How is the earthy matter separated ? What is black tin ? How many processes are necessary to bring it to the state of pure metal ? 226 METALLURGY. four to five hundredweight of metal. The melted tin thus pro- cured is next placed, without any addition, in a small reverbera- tory furnace, and exposed to a very gentle heat ; the purest part which melts first is drawn oif, 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. 127. The finest grain tin, however, is procured from the stream- tin ore, so termed because it consists of the loose crystals of oxide of tin found in the nibble or alluvial soil in some of the low grounds of Cornwall, having been washed thither by streams of water. These are free from the impurities of vein-tin ore, and the metal is consequently more perfectly reduced, and by more simple processes. Reduction of the Ores of Copper. 128. The copper ore, from which the metal is generally pro- cured, is the yellow sulphuret, a combination of copper with sulphur nnd iron. The next ore which occurs most abundantly is the sul- phuret, containing about eighty per cent, of copper. The oxides, carbonates, and arseniates of copper, are also found, but in smaller quantities, and they are of less importance. Both arsenic and sulphur adhere strongly to copper ; and as a small proportion of either renders the metal brittle and difficult to work, peculiar at- tention is necessary in the reduction of copper ore, in order that these substances may be separated. 129. The reduction of copper ore is completed by means of eight processes. The first is that of calcining in a reverberatory fur- nace, about 17 feet by 19, with a bottom or bed 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 in roast- ing the ore, pass almost wholly through the chimney into the open air. About three tons of the ore aro spread over the bottom of the furnace, being thrown in at the top, through a kind of funnel or hopper. The fuel is small coal, which is burnt at the anterior part of the furnace, and its flame passes over the surface of the ore in its passage to the chimney. 130. In this furnace, which is called the calcining furnace, the ore is roasted, without addition, with a dull red heat for twelve hours, being frequently stirred with a long iron rake, to expose fresh surfaces to the action of the flame. The ore is not melted here; but when roasted sufficiently to oxidate the iron, and con- In what sort of moulds are the pigs of tin cast ? What is meant by grain tin ? How is the best kind of this tin obtained ? From what kind of copper ores is the greatest portion of that metal ob- tained ? What effects have arsenic and sulphur on the qualities of copper ? How many processes are required to effect the reduction of copper ore ? How is the ore disposed for calcination ? REDUCTION* OF THE ORES OF COPPER. 227 vert the sulphur into sulphurous acid, jt undergoes the second pro- cess, namely, that of being melted ; and for this purpose is car- ried to another furnace, about 11 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 sullen, a little fluor spar to assist the fusion. 131. 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 metal in this state con- tains about one-third of copper, and consists of copper, sulphur, andiron. Five charges are melted in twenty-four hours. In the third operation, the' granulated metal is calcined to oxidate the iron, and it remains twenty-four hours in the furnace; during which it is often stirred and turned about, the heat being at first moderate, but gradually increased. 132. 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 become reduced during this process ; the oxygen of the copper combining with the sulphur passes off as sulphurous acid gas, while the reduced metal enters into combination with the sulphuret. The slags being skimmed, the melted metal is either tapped and suffered to run into water, where it is granulated, or else into sand beds, where it becomes solid. Its produce in fine copper is now about 60 per cent. 133. The fifth process is that of again subjecting the metal to the same mode of calcination as in the third process. The sixth pro- cess 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- Dpetal is roasted in the smaller furnace, chiefly to oxidate, and -finally to expel the volatile substances. From 25 to 30 per cent, of metal, by this process, becomes fused at the end of the operation, which continues from twelve to twenty-four hours, according to circuni- . stances. The metal is then tapped into sand beds, and the pi^ ; in this state are termed blistered copper. It is now fit for the re- finery. 131. The eighth process is that of refining or toughening. This appears to be a delicate process, the success of which depends on several circumstances that are judged of principally by the eye of the workman. It is conducted in a furnace similar to that for melting; and the chief objects appears to be that of abstracting How for melting and granulating? How for separating the iron ? What is the purpose of the fourth process ? What of the fifth ? the sixth ? the seventh ? What is blistered copper ? How is the refining pro^e^s conducted ? 228 METALLURGY. from the nearly pure metal the last portions of oxygen, which is effected by adding charcoal to the metal while in fusion, and stir- ring it occasionally with a pole of birch-wood, until the operator judges it to be pure Reduction of Ore of Lead. 135. The principal part of the lead procured, is derived from the ore called galena, which is a sulphuret of lead. Other ores, as the carbonate, the sulphate, and the oxide of lead, are occasionally mixed with the galena, which also frequently contains some silver, and when the quantity is sufficient to pay for the expense of separating it, that process is effected by exposing the roasted sul- phuret to the action of air and heat, in shallow earthen dishes. The lead thus becomes oxidated, or converted into litharge ; while the silver is left behind, retaining the metallic form. The litharge is afterwards reduced by fusing it with charcoal. 136. In the usual process for the smelting of lead ore, the galena being freed by the hand and the hammer from all such im- purities as can be readily separated from it, is beaten into small pieces, and after repeated washings and cleansings, is placed in a reverberatory furnace at a low red heat for some hours, to drive off the sulphur 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 as finished, the lead being converted into an oxide. 137. The reverberatory furnace commonly used is about 10 feet long and 6 feet wide internally, and about 2j feet deep ; the fire- place being at one end, from which the flame rises into the fur- nace. The quantity of ore usually thrown into the furnace at once is sixteen hundred weight, of one hundred and twenty pounds each, which quantity is spread over the floor of the furnace, and the doors are then closed. 138. The roasting, as above mentioned, being completed in a moderate heat, a small quantity of charcoal is added, the doors closed, and the reduction completed ; the lead, in a reduced state, lying at the bottom of the furnace, covered by a slag two or three inches in thickness, the slag is then tapped and runs off, and is used for mending the roads. Some quicklime, in powder, is now thrown down upon the metal in a state of fusion,which serves to raise and cake the remaining slag ; which, 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 fur- From what species of ore is lead generally obtained? How may silver be separated from an ore of lead ? In what manner is litharge reduced to pure metal? What is the common process for reducing galena ? What kind of furnace is employed ? What use is made of the scoriae from this process? REDUCTION OF THE ORES OF ZINC. 229 nace : the lead is, lastly, ladled from the pan into iron moulds, and left to cool. All these operations are repeated, by means of two sets of workmen, during every seven or eight hours. Reduction of the Ores of Zinc. 139. The ore of zinc, whether calamine or blende, is first broken into small pieces, and the galena, pyrites, and other impurities are separated as exactly as possible by the hand ; it is next calcined at a moderate red heat in a reverberatory furnace, by which the calamine is freed from its carbonic acid, or the blende from most of its sulphur. It is then washed, by which the lighter earthy parts are separated from the metallic oxide, which latter being dried is well mixed with one-eighth its weight of charcoal, by ^grinding the ore and charcoal together in a mill, as a prepara- tion for smelting. 140. The furnace in which the reduction is performed, is of a circular figure, somewhat like that of a glasshouse ; in it are fixed six large earthen pots or crucibles, about four feet high, nearly of the shape of oil-jars ; into the bottom of each crucible is inserted an iron tube, that passes through the arched floor of the furnace, and dips into a vessel of water placed beneath, while the other end of the tube rises inside 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 charcoal, the cover of each is very accurately luted, 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 being prevented from escaping by the closely luted cover, it de- scends through the central iron tube into the water, and is con- densed in small drops or globules, which are afterwards melted and cast into ingots. 141. Common zinc generally contains a little lead, copper, arsenic, iron, manganese, and probably plumbago, which often considerably impairs the quality of the alloys into which it enters. In order to get rid, in part, at least, of these impurities, the com- mon 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, converts them into sulphurets, which, rising to the top, form scoriae that may be skimmed off; this is to be repeated as long as ?.ny scoriee appear on the surface. What mechanical process is necessary to prepare the ores of zinc ? What furnace is employed to effect the calcination of this ore ? Describe the furnace in which the reduction of zinc ore is effected. In what manner and in what form does the metal make its escape from the melting pots ? How is zinc purified from other metals ? 230 METALLURGY. 142. The only metals which have been extensively applied to purposes of utility in the reguline or metallic state, are those, the modes of reducing which have been described in the preceding pages. Besides these, however, the metals called nickel, palla- dium, and rhodium, have recently been employed by artists,* though only to a very limited extent; and antimony, arsenic, and bismuth, though not used alone in the arts, yet serve by their combinations with certain other metals to form valuable alloys. 143. Gold in a state of absolute purity is so soft and pliable, that though it possesses a high degree of tenacity, it is by no means so well adapted for technical purposes as some of its-alloys. The addition of copper to this metal renders it much harder than before, and gives it a deeper colour. Silver, on the contrary, communicates to gold a lighter tint; and the mixed metal met with in commerce called "gilded ingots," consisting of silver alloyed with a little gold, is as white as pure silver. The gold coin of most European nations contains silver or copper, or both those metals. The standard or sterling gold of England is com- posed of twenty-two carats, f or parts of pure gold, and two of copper, which proportions appear, from the experiments of Mr. ITatchett, to form the best alloy for the purposes to which it is appropriated, resisting the influence of friction better than any other which had been tried. Besides jewellers' gold, which ought to be of the new standard, or eighteen carats fine, alloys of almost every degree of deterioration are used for making trinkets and other articles. 144. " The permanence and beauty of gold renders it a very desirable ornament, while at the same time its extensibility ena- bles us to use it where its expense and weight would otherwise preclude its employment. Where gilding is performed upon metallic surfaces, it is usually done by a solution or amalgam of gold in quicksilver. This is called water gilding, and the process exhibits an instance of chemical attraction, and subsequent de- composition by heat. Steel is sometimes gilded by the ethereal solution of gold.t What effect on the usefulness of gold is produced by alloying it wilh copper ? What proportion of pure gold is contained in the alloy used by jewellers ? How is water-gilding performed ? * See Treatise on Chemistry, Nos. 412 and 457. t The mode of computation by carats, with reference to the alloys of the precious metals, has long been employed in England. Every mass of al- loyed gold is supposed to be divided into twenty-four carats, and the rela- tive quantity of gold it contains is denoted by the number of carats of that metal in the mass ; as gold of twenty-two carats, or standard gold for coin ; gold of eighteen carats, or gold of the new standard, used for watch-cases, &c. This method does not so conveniently admit of the appreciation of various quantities of alloy, as that adopted in France, where the pure gold in alloys is estimated by thousandth parts ; thus gold of eighteen carats, or containing of alloy, would by the French method be said to be of the standard expressed by "750. I Brande's Lect. on Mm. Chern. in Journ. of Science, vol. iv- p. 212. ALLOYS OF TIN". 231 145. Silver forms useful alloys with copper, especially for coin and plate. The addition of a small proportion of copper to silver renders the metal harder and more sonorous, without materially impairing its colour. The silver coin of the United States con- tains for every 12 ounces of coin 10 ounces 14 pwts. 4^ grains of pure silver, and 1 ounce, 5 pwts. 19 T 8 ^ grains of copper. Copper is plated with silver for various purposes, and by means of different processes. These metals may be united by a mode resembling the operation of welding; a plate of silver being ap- plied to the surface of one of copper, and the mass compressed by passing it between steel rollers; after which it may be worked into different forms for use or ornament. An inferior kind of plated copper is formed by applying to the surface of that metal an amalgam of silver, and* the mercury being driven off by heat, the surface is burnished. The brass dials of clocks, and the scales of barometers and thermometers, are silvered on the surface by rubbing over them a mixture of chloride of silver, chalk, and pearlash. 146. The compounds of mercury with other metals are called amalgams. That of tin is extensively used for silvering (as it is termed) looking glasses. For this 'purpose tin-foil is spread on a flat stone, and covered with mercury ; the glass is then placed upon the metallic surface, and the excess of mercury being pressed but, the remainder amalgamating with the laminated tin adheres to the glass, forming on the opposite side of it a brilliant reflect- ing surface. An amalgam of bismuth 2 parts, lead and tin 1 each, and mercury 4 parts, is used for silvering the interior of hollow glass globes. This is effected by introducing into the globe a small quantity of the metallic alloy, which is to be melted by immersing the globe in hot water ; and then by turning it gradually in all directions, the bright coating will adhere to the inside of the glass. Zinc, amalgamated with mercury, forms a composition which increases the electrical energy of glass excited by friction ; and it is therefore applied to electrical machines. 147. Tin constitutes the basis, or enters into the composition. of various useful alloys. An extremely important application of this metal, which has been carried to high perfection in modern times, is the coating of other metals. Copper vessels thus covered seem to have been certainly in use among the Romans, and there is reason to believe that they also knew how to apply tin in the same manner to the surface of iron. The process of tinning iron, or making tin-plate, consists chiefly in dipping What qualities of silver are affected by alloying it with copper? In what manner is copper plated with silver? How are clock faces and thermometer scales vvhilcned ? How is the silvering of looking glasses effected ? How are globular mirrors formed ? For what purpose is amalgam employed in electrical experiments 'i For what purpose is tin extensively employed in the arts ? 232 METALLURGY. sheets of iron into a vessel of melted tin, the surface of which is prevented from oxidation by being covered with melted tallow. The tin thus unites with the opposite surfaces of the iron, forming with it an alloy to a slight depth. Various precautions and mani- pulations are requisite to ensure the complete success of the ope- ration, and conduct it in the most economical manner, of which ample information may be found in a valuable paper on the manu- facture of tin-plate, by Mr. Samuel Parkes.* 148. The process of tinning the interior of copper vessels for culinary purposes is effected on similar principles. The copper surface is first polished, and then coated with sal ammoniac and pitch, to prevent oxidation, and the vessel being heated, the tin finely divided, and also heated, is applied to it, and adheres to its superfices. The composition of bronze used by the ancients in casting medals, figures in relief, and for other purposes, is not exactly known ; and it is probable that different kinds of alloy were used by artists in different countries, and for various purposes. Tin and copper, however, appear to have been the chief, if not the sole constituents of this alloy ; and compounds of those metals are still employed for works of an analogous description. 149. Pewter is said to be an alloy of tin and copper, containing 1 part of copper to 20 of tin ; but the composition of this sub- stance is extremely variable. Common pewter consists of cheaper materials, being formed of 80 parts of tin and 20 of lead ; while the finest pewter has been stated to contain about 12 parts of tin and 1 of antimony, with a small portion of copper. Britannia metal, now frequently used for making teapots, spoons, and other articles, forming a cheap substitute for silver, much resembles the last mentioned sort of pewter. Its composition has been thus stated : The best block tin 3 cwt., antimony, 28 lb., copper and brass, of each, 8 lb. 150. Speculum metal, a brilliant alloy, used for the construc- tion of concave mirrors for reflecting telescopes, is another alloy into the composition of which tin always enters, thoagh its chief constituent is copper. The grand object in the formation of this substance is to obtain a reflecting body which shall yheld a single distinct image, have hardness to admit of its being highly polished, and a surface as little as possible liable to become tarnished by air and moisture. Various metallic combinations have been em- How is tin plate manufactured ? How is copper tinned ? Of what materials is bronze composed What are the ingredients of pewter? Britannia ware? Of what are the mirrors for reflecting telescopes composed ? What are the great purposes to be attained in this case ? * See Journ. of Science, vol. viii. ; Memoirs of the Manchester Philoso- phical Society, N. S., vol. iii. ALLOYS OF COPPER. 233 ployed for these purposes, by different artists and experimental philosophers, among which it will be sufficient to mention the alloy of 1 part tin and 2 of copper, recommended by Mr. Madge; and the more complex metal formed of copper 32 parts, tin 15 or 16 parts, and brass, arsenic, and silver, each 1 part, 151. Lead when alloyed with other metals seems to impair their tenacity, while it renders them more fusible. The most use- ful of its alloys is type-metal, composed of about 16 parts lead, and 1 antimony and copper; but the proportions, if not the in- gredients themselves, differ in different foundries, a good deal of secrecy being observed with respect to the methods of forming this compound. The chief object in the combination must be to obtain complete fusibility, so that when cast the type shall be per- fect, forming an ex-act counterpart of the matrix ; and likewise that the letters may be hard enough to wear well, and stand their work firmly, having just so much tenacity as to break rather than bend, when under the application of great force. An alloy of lead and antimony is also used to majte plates on which music is en- graved. 152. Copper forms various valuable alloys, the most important of which is brass, in which it is combined with zinc. This alloy is usually produced by mixing granulated copper with calamine (ore of zinc) and charcoal, and exposing the mixture to a degree of heat sufficient to reduce the ore, and the revived zinc uniting with the copper in a state of fusion, the melted alloy is cast into plates. The proportions of the respective metals employed are variable, constituting different kinds of brass : but it usually con- tains from 12 to 18 percent, of zinc, according to Brande; though Dr. Thomson found, in the valuable alloy called Dutch brass, 70 parts of copper and 30 of zinc. Pinchbeck, Prince Rupert's metal, Dutch gold, tombac, and similor, are alloys composed of copper and zinc, the proportion of the latter metal being smaller than in brass, and hence they are formed by the addition of copper to brass. Tutenag is said to be an alloy of copper with zinc and a little iron. In a metallic substance called white copper, brought from China, Dr. Fyfe found, besides the three metals just mentioned, a large proportion of nickel. The following table contains a view of the composition and ap- plication of a number of the most useful alloys employed in the arts; it is principally due to ihe labours of Messrs. Chaudet, of Paris, and P. N. Johnson, of London, and is condensed from a table, communicated for the Journal of the Franklin Institute, by Mr. F. Peale. What are some of the proportions observed in making type metal ? What effect has lead on the melals with which it is mixed ? How is brass manufactured ? What is the composition of Dutch brass? What is thai of tutenag ? What ingredients have been found in white copper? * See Jour. Frank. Inst. vol. xvi. p. 219. u 2 234 METALLURGY. Talk of Alloys, Solders, and Amalgams, used in the Arts. Alloy of Gold Coin. (Fr. Stand.) Gold 900, Cop. 100. " Silver Coin. (Fr. Stand.) Sil. 900, Cop. 100. " Gold Coin. (U. S. Stand.) Gold, 899.22, Cop. and Sil. 100.78. " Silver Coin. (U. S. Stand.) Sil. 892.43, Cop. 107.57. " Gold Coin. (Eng. Stand.) Gold, 916.67, Cop. and Sil. 83.33. " Silver Coin. (Eng. Stand.) Sil. 925, Cop. 75. " " Billon." (Fr. Stand.) Cop. 800, Sil. 200. " Gold Medals (Fr. Stand.) Gold, 916, Cop. 84. " Bronze Medals.* Cop. 920, Tin 80. " Jewellery. (Fr. Stand.) Gold 750, Cop. 250. " Silver Plate. (Fr. Stand.) Sil. 950, Cop. 50. " Imitation of Gold. Cop. 905.5, Tin 94.5. " Imitation of Silver. (Park.) Cop. 578.0, Zinc 271.5, Nick. 142.7, Lead 7.7. " ' Cannon. Cop. 900.9, Tin 99.1. " Statues, sometimes lead and zinc. Cop. 914.0, Zinc 55.3, Tin 17.0, Lead 13.7. " Bronzes and Candelabras. Cop. 784.8, Zinc 172.2, Tin, 28.7, Lead 14.3. " Mounting of Fire arms. Cop. 800, Zinc 170, Tin 30. " Cymbals,f Tarn Tarns, or Chinese Gongs. Cop. 800, Tin 200. * 4 Bells. Cop. 750, Tin 250. " Reflectors of Telescopes. Cop. 6G6 Tin 333. " Brass for the Lathe4 Cop. 658.0, Zinc 318.0, Lead, 21.5, Tin 2.5. *' Brass for the Hammer. Cop. 701, Zinc 299. " Types. Lead 800, Antim. 200. " Fusible in boiling Water. Bism. 500.0, Lead 312.5, Tin, 187.5. " For Plugging Teeth, fusing at } 169. Bism. 454.5, Lead V8 B-f 5 L+3T+1 M. 284.1, Tin 176.5, Mer. 90.9. _) " For Tinning Iron. Tin 888.9, Iron 111.1. " Ductile Gold of 18 carats, or 950 mllliemes.|| Cop. 990, Gold 10. * The medals made from this alloy have the advantage of being struck by a few blows of the press, and of wearing a long time. "t This alloy is very hard; it is annealed by dipping, while red-hot, into water, and is then malleable ; whilst, if suffered to cool gradually, it is excessively hard ; this important fact is due to M. d'Arcet, who has thus furnished the means of fabricating, in France, cymbals, &c., formerly im- ported, at great cost, from China. \ The proportions indicated in this alloy having been found by analysis, il is evident that the tin is present by accident Sometimes a small quantity of copper is added to these two metals. il The previous combination of the alloy is found to' produce ductile gold, when the same metals would prove the contrary if mixed directly. TABLE OF ALLOYS, &C. USED IN THE ARTS. 235 " Bells of Mantel Clocks. Cop. 750, Tin 250. " Pivots of Artificial Teeth. Plat. Sil. proportions unc. Do.* do. and Philosophical Instruments. Pallad. 500, Sil. 500. " Springs of Artificial Teeth.f Pallad. 312.5, Sil. 312.5, Cop. 312.5, Iron, 62.5. Solder for Gold of 750, or 18 carats. Gold of 750, 666.7, Cop. 166.6, Sil. 166.6. " Silver of 750. Sil. 666$, Brass 333. " Brass. Cop. 500, Zinc 500. " Lead. Lead 666#, Tin 333. Amalgam of Gold for Gilding on Metal. Mer. 900, Gold, 100. " of Silver. Mer. 850, Sil. 150. " for taking impressions of Seals. Cop. and Mer. unc. " for Silvering Mirrors. Tin 700, Mer. 300. " for Silvering Globes of Glass. Mer. 800, Bism. 200. " for the Cushions of Electrical Machines. Mer. 500, Tin 250, Zinc 250. * This alloy is extremely important ; it is used for all those purposes in the fabrication of philosophical instruments, for which platinum was for- merly applied, being superior to it in hardness and colour, and yet inoxida- ble under all the usual circumstances. t This is an extremely useful alloy, having a degree of elasticity only exceeded by steel, with all the advantages of superior lightness and hard- ness over platinum ; this, and the preceding, are due to Mr. Percival N. Johnson, of London. t This amalgam is hard, and melts at a low heat ; it was used by the French police, under the administration of the celebrated Fouche, for the purpose of opening and resealing the letters that passed through their hands. Works in the Department of Metallurgy. Gray's Operative Chemist, article, metals. Library of Useful Knowledge, Treatise on Manufacture of Iron. Lardner on Manufactures of Iron. Bigelow's Technology, p. 384. et seq. Bakewell's Introduction to Geology. Ure's Chemical Dictionary, various articles on Ores and the particular metals. Parke's Chemical Essays. 2 vols. 8vo. Journal of the Franklin Institute. Metallurgie Pratique. Dumas Traite de Chimie applique aux Arts. Karsten on the Manufacture of Iron, (French edition.) Annales des Mines, passim. MINERALOGY. 1. THE object of this science is to describe the general compo- sition, characters, varieties, forms, and combinations of mineral bodies. A mineral may be described as a substance destitute of organization and vitality, found on the surface of the earth, or im- bedded at various depths beneath it, in veins or strata, which are worked for the extraction of such substances, by excavations, called mines. Mineralogy maybe distinguished from chemistry, as relating to the forms and properties of certain bodies as they are presented to us by nature ; while the latter science instructs us how Vo procure a multitude of artificial products, derived alike from the animal, vegetable, and mineral kingdoms, and to explore their properties, especially as it respects their modes of combina- tion. Mineralogy is likewise to be distinguished from geology, with which, however, it is intimately connected. ^ 2. It is the province of the geologist to investigate the general structure of the earth, and the nature and arrangement of the great masses of which it is composed. The mineralogist, on the other hand, confines his attention to individual portions of unor- ganized matter, distinguished by peculiar and specific characters. In the study of geology it is of the utmost importance to be ena- bled to examine the objects of research, in situ , and to ascertain their relative connexion and arrangement, in the formation of rocks, mountains, plains, subterraneous strata, and, in general, of all the great masses, the assemblage of which constitutes the solid shell, or exterior surface of the terrestrial globe. The nature and properties of minerals may be investigated and ascertained, with- out any reference to the situations in which they are produced. 3. Thus connected as mineralogy is with chemistry, on the one hand, and with geology on the other, it displays features suffi- ciently distinct from those of either; yet, at the same time, the objects of these sciences so far correspond, that a complete know- ledge of mineralogy cannot be obtained without a previous ac- quaintance with chemistry; nor can the information which these sciences united afford, relative to the unorganized productions of nature, be applied to a more exalted purpose than that of aiding our researches concerning geology.*, What is the object of the science of mineralogy ? In what points does this science differ from chemistry? How is it distinguished from geology ? How is unorganized matter regarded by the mineralogist? Is the locality of a mineral of any importance in the decision of its cha- racter? * The necessity of exact mineralogical knowledge to the geologist lias been very justly and forcibly expressed by Mr. Aikin in the introduction to his Manual of Mineralogy, published in 1815. He says : "The absolute necessity of extreme accuracy in discriminating one species of mineral 236 CLASSIFICATION OF MINERALS. 237 4 Mineral substances may be discriminated from each other by their mode of crystallization or aggregation, and the optical pro- perties depending on their peculiar forms ; by their physical charac- ters, as colour, lustre, transparency, hardness, consistency, density, or specific gravity ; as also in some cases by their taste or odour, by their relations to electro-magnetism, and finally by their chemical constitution. 5. Any or all of these various qualities and affections may be taken into consideration in forming classical arrangements of bodies belonging to the mineral kingdom of nature. Hence a diversity of systems and arrangements have been contrived by various mineralogical writers. But those who have been engaged in such theoretical speculations, have succeeded so indifferently that a distinguished professor of mineralogy, in his remarks on the state of the science in England, says : " The value of a method of classification seems to be looked upon as a point not worth discussing; any one method is considered as good or as bad as any other. This opinion, indeed, is openly maintained by some of our best mineralogists. Their labours have been em- ployed solely and exclusively in the crystallographical and che- mical analysis of particular species ; land I am not aware that any attempt has been made, among us, to establish any proposition in- cluding a class of species of minerals, with the exception of Sir David Brewster's optical researches."* &_ But on the continent of Europe the case is widely different; a number of mineralogical systems having been published of late years in Germany, France, and Sweden ; some of them founded on the chemical constitution of minerals, some on their crystallo- graphical or other physical properties, and others which may be called mixed systems of classification, depending on a combined In how many different ways may minerals be distinguished from each other ? Whence has arisen the diversity of systems of arrangement in the min- eral kingdom? On what characters did Brewster attempt to form the species of mi- nerals ? On what basis have the writers of continental Europe founded their di- visions of the subject? from another, is too obvious to require any further remark, if examples were not perpetually presenting themselves of persons very slenderly pro- vided with these rudiments of the science, who yet undertake geological investigations, and with a peremptoriness generally in proportion to their ignorance, challenge the credit of new discoveries, or call in question the observations of their predecessors. It is, indeed, very true that geological speculations are as facinating to the student as the discrimination of species is generally repulsive ; yet it ought to be borne in mind that as all sound scholarship is founded upon grammar, so all sound geology depends primarily on a familiar acquaintance with the distinctive characters of simple minerals." Encyclop. MetropoL Mixed and Applied Sciences, vol. iv., Mineralogy, p. 465. * Whewell on the Recent Progress and Present State of Mineralogy, in Report of British Association for 1832, pp. 324, 325. 238 MINERALOGY. view of physical and chemical characters. .The number, variety, and discrepancies of the systems of mineralogy, which have been recently proposed, abundantly evince tbe difficulties that attend the subject : and though we should not be inclined to admit thai all methods are alike in point of value, yet, it must at least be ac- knowledged, that various modes of arrangement might be pointed out, the advantages and disadvantages of which would so nearly correspond, that it would be difficult, if not impossible, to decide which had the superiority. 7. But whatever kind of arrangement might be adopted, atten- tion must necessarily be paid both to physical and chemical characters, in arranging and describing the different genera and species into which mineral bodies may be distributed. Crystallo- graphical properties are among those characteristics of minerals which are of the highest importance ; for though some bodies belonging to the mineral kingdom exhibit no traces of crystal- lization, yet they are comparatively few and inconsiderable; hence the study of crystallography is necessarily connected with that of mineralogy, and the subject is in many respects so import- ant, as to render it deserving of especial consideration ; therefore, in addition to the remarks on crystalline forms which may occur in the notices of the several kinds of minerals, some further ob- servations on crystallography will be added to the latter part of this treatise. 8. The physical characters of minerals require a few prelimi- nary remarks.; Colour is one of those properties of mineral bodies, which/fhough frequently serviceable in distinguishing them from each other, is by no means constant; for though there are some minerals which always exhihit the same tints, there are others which display the utmost diversity ; so that specimens having an apparent identity of chemical constitution, and, in most respects, of physical character, will yet be found of very dif- ferent colours. This is especially the case with those mineral bodies which are considered as precious stones, and when cut and polished, used as ornaments. 9. Thus the gem called the sapphire, sometimes exhibits its characteristic sapphirine, or blue colour, and is likewise found purple, red, green, yellow, gray, and white, or perfectly transpa- rent. Topazes are found yellow, pale blue, green, transparent or colourless, and sometimes of a fine red. Garnets occur not only red, but also black and brown. The diamond is seldom entirely free from colour, and some are found blue, pink, dark brown, or yellow. Some minerals, as the opal, exhibit different colours when viewed by transmitted light, from those which appear when seen by reflected light. "\ What two characters of minerals must necessarily be regarded in making systematic arrangements ? What degree of constancy is found in the colours of minerals? What examples of diversity in colour can be cited ? PROPERTIES OF MINERALS. 239 10. Yet notwithstanding these anomalous phenomena, the colour may frequently be employed as a discriminating charac- teristic of mineral bodies; for though, when considered alone, it might afford no certain indication of the nature of a mineral, yet, taken in conjunction with other characters, it will be found frequently useful, as enabling us to describe and distinguish mineral substances. 11. {Lustre is one of the external characters of minerals, which is of considerable importance. The principal kinds of lustre are the adamantine, the vitreous, the oily, the resinous, the fatty, the pearly, and the metallic ; to which may be added the semi-metal- lic. The metallic lustre is peculiar to certain metallic ores, and is always accompanied by opacity ; and the semi-metallic charac- terizes various earthy as well as metalliferous minerals. 12. /Mineral substances also differ in the degree as well as the kind ol lustre which they display. Thus the" highest degree of brilliancy is termed splendid, whence we descend through the va- rious grades of shining, glistening, and glimmering, till we arrive at that which is called dull, to be observed in most of those minerals the fracture of which is earthy. This characteristic may also be further modified, and terms employed to denote interme- diate degrees of lustre. Thus it may be stated that the lustre of a mineral is strongly or faintly glimmering, passing into glistening, but such distinctions are scarcely necessary, except in describing newly discovered substances. 13. 'VThe different kinds of lustre undoubtedly depend upon optical differences in the surfaces, which differences have not as yet been clearly explained.) Professor Breithaupt is in the habit of showing, by the superposition of a number of watch-glasses, that the pearly lustre results from the lamellar structure of a transparent mass. The very curious difference between the opti- cal properties of the surfaces of metals, and of transparent bodies, has been traced on different roads, by Sir David Brewster and by Professor Airy, and both agree in considering the optical properties of the diamond as intermediate between the transparent and the metallic character, though they do not agree in their representa- tion of the peculiar laws which the diamond discloses. When the connexion of these properties with those of other bodies is clearly made out, we shall probably learn more distinctly than we now can, what is the precise distinction of metallic, adamantine, and vitreous lustre."* 1 14\ Transparency is a property which does not belong to all What dependence for colour is found among minerals on the direction of the light by which they are viewed ? What classification may be formed on the ground of the lustre of mine- ral substances? What property is found connected with metallic lustre ? flow many divisions may we form on the degree of brilliancy ? To what is the difference in lustre probably ascribable ? * Whewell on Mineralogy, in Rep. of Brit. Assoc. for 1832, p. 327. 240 MINERALOGY. minerals, and in those which possess it, it exists in different de- grees. ^Some minerals are semi-transparent, as cornelian, and certain kinds of obsidian ; others are merely translucent, or but little removed from opacity. A few minerals which appear opaque, when examined in the air, become more or less transpa- rent if immersed in water. This is the case with a sort of opal, hence called hydrophane.T 15. Hardness is very important, because it is a very constant pro- perty in most simple minerals. Professor Moris, of Vienna, has formed a scale of numbers to indicate the degree of this property respectively belonging to any mineral. In this scale the hardness of common talc is 1, of gypsum 2, of calcspar 3, of fluor spar 4, of apatite, or asparagus stone 5, of feldspar 6, of quartz 7, of topaz 8, of corundum 9, and of diamond 10. \ 16. The hardness of a mineral may be ascertained by trying whether it will scratch another, the relative hardness of which is previously known. Hence, according to the preceding scale, supposing the hardness of a mineral to be indicated by 5, it must be inferred that it is intermediate between 5 and 6, and therefore that it would scratch apatite, and be scratched by feldspar. Pro- fessor Breithaupt, of Freyberg, has extended the numerical scale of Mohs from 10 to 12, by introducing mica between gypsum and calcspar, and sodalite between apatite and feldspar, as inter- mediate degrees; and it is obvious that, if it were thought desir- able, further distinctions might be made, and the scale might be enlarged." 17. It is an observation of some importance with respect to the hardness of several minerals, that it appears lobe different in dif- ferent parts, and even in different directions. Thus the edges and solid angles of crystals seem to be harder than their faces ; and in the diamond, serviceable cutting points can only be obtain- ed from natural crystals. The diamond-cutters distinguish the angles of a dodecaedral crystal into hard arid soft points, the for- mer consisting of those which are also the angles of the primitive octaedron, and which cannot be split or broken off, but must be ground down with diamond powder ; while the low triangular pyramids, which form the other points, may be removed by cleavage. Kyanite affords an example of a mineral, the hardness of which will differ according as it is scratched, along or across the direction of its axis. What effect on the transparency of certain minerals is derived from fill- ing their pores with water? What substances have been adopted as standards of hardness ? How is the hardness of an unknown mineral to be tested ? How is the hardness of a mineral found to vary ? What distinction is formed by diamond cutters in regard to the angles of crystals? What example of different degrees of hardness, depending on direction is known to exist ? * From the Greek "Y, water, and aVw, to shou. light PROPERTIES OF MINERALS. 241 18. Consistency is a property which is intimately connected with hardness, but of a more general nature. A substance may be at the same time very hard and very brittle, or it may be extremely soft, and at the same time tough or tenaceous. Thus euclase and an- thophyllite are hard bodies, but easily frangible, or broken by a blow; while asbestus or amianthus, which are very soft and flexible minerals, are at the same time very tenacious, so that fibres of these substances may be twisted into threads, and woven to make cloth. 19. Density , or specific gravity, is one of the properties of mineral bodies deserving of attention, as furnishing the means of discrimi- nating them from each other. The nature of this property of matter with regard to substances in general, has been amply noticed in the preceding volume of this work, in which, likewise, the modes of ascertaining the specific gravity of bodies, has been described and illustrated.* 20. Much attention has been paid to specific gravity, as a cha- racteristic property of minerals, by Professors Mohs and Brei- thaupt, who have determined most minutely the value of this ele- ment for very extensive series of minerals. Beudant has discovered that large crystals, and especially bacillary masses, are inferior in specific gravity to small crystals ; and he therefore recommends the pulverization of minerals previously to trials of their specific gravity, in order to obviate the uncertainty that might arise from these differences in the mode of aggregation. Magnus found that garnet and similar minerals, when melted, and again solidified in a glassy but uncrystalline state, have their density diminished by the operation ; the Greenland garnet, for instance, when thus treated, had its specific gravity reduced from 3.9 to 3.05.f 21. Taste and odour wee sensible qualities of minerals, which cannot be very extensively applied to practical purposes. Taste is chiefly confined to saline minerals, and is sufficiently obvious in most cases where it exists, as in rock-salt, (chloride of sodium,) and alum, (sulphate of alumine.) Some minerals are distinguished by a peculiarly disagreeable smell, as is the case with a particular kind of limestone, which is hence called swinestone, or fetid limestone. 22. '\glectro-magnetism, or electricity, manifests its influence in some minerals, by the production of a phosphorescent light, when they are subjected to collision or friction ; and others, by friction or How may minerals be distinguished in reference to consistency ? On what is the difference in the specific gravity of mineral substances of the same species sometimes found to depend ? What classes of minerals are possessed of taste ? How does the possession of electrical properties by a mineral become apparent ? * Scientific Class Book, pt. i. p. 151. t Whewell on Mineralogy, in Rep. of Brit. Assoc. for 1832, p. 326. X 242 MINERALOGY. the application of heat, may be made to attract liorht bodies, in the same manner as excited glass or sealing wax.* J 23. There are many terms denoting properties or appearances of mineral bodies which are of frequent occurrence in treating concerning them, and may therefore be briefly explained. ^Minerals are said to be adhesive when the newly fractured surface adheres it applied to the tongue, as is the case with slate.} (Those which may be divided into thin plates are termed lamellar minerals. /Crystals, the length of which greatly exceeds their other dimen- sions, are called bacillary crystalsOand-Avhen they are very much attenuated, they are termed capiuary,}and'i they diverge from a common centre, scopeform fibres!; .Irregular globular bodies are styled nodules, or nodular masses, and those which have no sym- metrical form, are called amorphous.^ Specular means smooth, shining, mirror-like; tabular, approaching to flatness; and vesicu- lar, sponge-like, or full of holes or vesicles. 24. Minerals are properly definite compounds, in various states of complication, of those elementary bodies with which chemis- try has made us acquainted, except in a few instances; some bodies, as gold and carbon, being presented to us by nature in a pure and uncombined form. Among compound mineral bodies there are some, however, which appear to be simply aggregated, or to consist merely of mingled masses, while by far the greater number are chemical compounds. When minerals are simply aggregated, as for instance, when gold is found in limestone, the separation of the metal may be effected by the mechanical operations of pound- ing and washing ; but in the case of chemical compounds, as sulphur and copper, (copper pyrites,) or oxide of tin, called wood tin, the separation of the metal from the sulphur in the first case, and from the oxygen in the second, can only be effected by chemical processes, the nature of which has been already de- scribed in the Treatise on Metallurgy. What is meant by the term adhesive as applied to minerals ? What minerals are called lamellar 1 How are the terms bacillary and capillary applied ? What ones are called scopeform minerals ? How are the terms nodular and amorphous distinguished from each other? How are specular, tabular, and vesicular used in mineralogy ? How may simple aggregates be separated ? * The effect of heat and friction in exciting phosphorescence or electric li 27. Both the system of HaUy and the more modern doctrine are founded on a presumed relation between chemical composition and crystalline form, examples of which are too numerous to admit ot the least question, but concerning the nature and extent of the relation we are not yet qualified by any means to decide ; and hence arises a manifest source of imperfection and discrepancy in the mineralogical arrangements derived from it. Observations that have been made of the analogy of form between bodies vary- ing in composition, led to the assumption of the principle of iso- morphism, or plesiomorphism ; which, as being connected with crystallization, will be further noticed in treating of that subject. 28. Professor Berzelius has constructed an arrangement of mi- neral bodies, founded on their relative electro-positive and electro- negative properties. This system, since it was first proposed in 181G, has been considerably modified, especially in consequence of the discoveries that have been made relative to isomorphism ; and though still necessarily imperfect, it may be regarded as the What was the basis of Werner's divisions ? How did Haiiy form his classes? How did he classify uncrystallized substances? How many distinct characters are embraced in the modern definition of crystals ? What characters has Prof. Berzelius made the foundation of his system ? * Whcwcll on Mineralogy, in Rep. of Brit. Association for 1832, p. 350. ARRANGEMENT OF MINERALS. 245 nearest approximation yet obtained towards a regular and consist- ent classification of mineral substances. 29. " The order established by the electro-chemical relation of bodies is supposed to be generally preserved in all their combina- tions. Thus, if A be electro-negative in respect of B and of C, B will generally be electro-negative in relation to C ; but this ap- pears not to be universally so ; and sometimes one electro-negative body is found combined with two or more bases, and sometimes two acids are combined with a single base. If, says Berzelius, with these theoretic notions in our mind, we look through the pro- ductions of the mineral kingdom, the apparently confused combi- nations which minerals present will be immediately pervaded by regularity and order. We perceive an extensive class of minerals into which silex enters as a constituent, assuming the character of salts, either simple, double, triple, .or quadruple ; and with various excesses of the acid or the base. ' 30. Un the same manner we perceive the oxides of titanium, of tellurium, and of other metals, performing the functions of acids, and thus reducing the whole series of minerals to one uniform system of classification j) and the doctrine of definite proportions introduced within a few years into chemistry, might, if we could fully avail ourselves of its aid, be said to confer on this system of mineralogical classification a degree of almost mathematical precision. But in consequence of the difficulty of ascertaining the proportions of the actual ingredients of minerals, and the still greater difficulty of distinguishing those which are essential to the species analyzed, we are not yet enabled to confer on a chemical classification all the advantages offered by the improved doctrines of chemistry."* 31. Professor Whewell has remarked that though we do not at present possess any system of arrangement on strictly chemical principles, bringing together in all cases, the substances which most resemble each other in external properties, yet the arrange- ments recently proposed by Berzelius and others, may be regarded as approaching to such a perfect system, whether they be founded upon external characters or on chemical principles. " The new system of Berzelius, or that of Beudant, or indeed any of the new chemical systems, would produce a grouping of substances which would at once be recognised as far more natural than that of Haiiy or Phillips. The last system of Berzelius has been adopted in the arrangement, of the minerals of the British Museum." 32. The ensuing descriptive notices of the principal minerals is arranged on the electro-chemical classification or system of Ber- zelius. What character have the mineral substances into which silex enters as a constituent principle ? What function do the oxides of titanium and tellurium perform? * Encycl. Metrop. Mixed Sciences, vol. iv., Mineralogy, p. 468. x2 246 MINERALOGY. (I-) (2.) Table of Mineral Classes. Electro-positive metals and their alloys. Electro-negative bodies and their combinations. Carbon and carburets. Selenion and seleniurets. Sulphur and sulphurets. (3.) Oxides of electro-positive metals. (4.) Oxides of electro-negative bodies and their combinations. Alumina and aluminates. Silicic acid and silicates. a. Silicates with simple bases. b. Silicates with compound bases. Titanic acid and titanates. Colurnbic acid and columbates. Antinionic acid and antimoniates. Scheelic acid and scheelates, or tungstates. Molybdic acid and molybdates. Chromic acid and chromates. Vanadic acid and vanadiates. Boracic acid and borates. Carbonic acid and carbonates. Arsenius acid and arseniates. Phosphoric acid and phosphates. Nitric acid and nitrates. Sulphuric acid and sulphates. (5.) Fluorides and fluates. (6.) Chlorides. (7.) Organico-chemical bodies, or minerals derived from or- ganized matter. Salts. Resins. Bitumens Coals. (1.) Electro-positive Native Metals. 32. Iron, though one of the most common of the metallic bodies, is not often found in the native state^in consequence of the power- ful tendency which it possesses to combine with oxygen, sulphur, and other substances.! ( Most of the existing specimens of native iron are supposed to liave derived their origin from meteoric stones ; though this metal is said to have occurred in the state of What is the first class of mineral substances according to Berzelius ? What is the second ? How many subdivisions are comprehended under the second class? What is the third class ? What the fourth ? What subdivisions belong to this class? What is the fifth class ? What is the sixth ? How many subdivisions are found under the seventh ? Why is not iron found pure in its native state ? ELECTRO-POSITIVE METALS. 247 pure iron ore, massive, and in leaves of a gray colour, having a fracture like that of steel, and some degree of malleability. Some notice of meteoric stones will be found in another part of this volume ; but besides those masses of ferruginous matter, un- doubtedly of aerial origin, large blocks of iron, in which the metal exists in various degrees of purity, have been discovered in dif- ferent parts of the world. 34. Among these blocks of iron may be mentioned one found at Ellenbogen, in Bohemia; the large mass discovered by Profes- sor Pallas, on the top of a hill, between Abakansk and Belskoi Ostrog, on the the banks of the Jenesei, in Siberia, which ori- ginally weighed about 1680 pounds; a mass found in Southern Africa, and now in the cabinet of Haarlem, in Holland, weighing about 250 pounds ; an immense mass of native iron from Otumpa, in the Gran Chaco Gualamba, in South America, described by Don Rubin de Celis, who estimated its weight at fifteen tons ; a mass of iron from Atacama, resembling the Siberian iron ; a large mass of iron preserved at Aix-la-Chapelle ; two large blocks on a hill in the country of the Esquimaux, near Davis's Straits, pieces of which the people use for making the rude blades of their knives and harpoons ; a mass of iron weighing 103 pounds, found in September, 1829, near the castle of Bohumiltitz, in the circle of Prachin, in Bohemia; and one found recently at Magdeburg. Meteoric stones, fell at Weston, Connecticut, in 1807, at Long Branch, N. J., Aug. 15, 1829, and at Munro, Geo., May 8, 1829; of these, specimens are preserved in the collection of the Academy of Natural Sciences of Philadelphia. Such of these masses as have been analyzed, have in general been found to consist principally of iron alloyed with nickel, but the Magdeburg block, according to the analysis of Professor Stromeyer, contains, besides iron and nickel, cobalt, copper, molybdena, and arsenic ; and the Bohu- miltitz mass appears to contain, with iron and nickel, small quantities of plumbago and sulphur. Native iron, not meteoric, is said to have been found about 1823, in the town of Canaan, in the state of Connecticut, forming a thin stratum, or vein, in a mass of mica-slate. It was uncombined with nickel, and quite malleable. 35. Native copper is usually found unalloyed, except with small portions of iron and gold* - j t ex hibits a great variety of beautiful forms, besides those of common crystals. Native copper appears of a brighter or darker colour, as it is more or less tarnished, and occurs some- times in considerable masses, What opinion has been advanced respecting the origin of masses of na- tive iron found on the surface of the ground ? Enumerate the localities of some of those masses. What other ingredients besides iron are found in some of them? 248 MINERALOGY. one of which, found by Mr. Hearne, in the country round Hudson's Bay, is described by that gentleman in his journal. Large masses of native copper also occur on the shores of Lake Superior. Some specimens are foliated, some branching, others in the forms of octaedral, cubic, prismatic, or other crystals; and this metal some times displays arborescent, and sometimes fibrous or filiform figures, as represented in the margin. 3G. Bismuth is found native, massive, disseminated, and arbores cent, imbedded in jasper or other minerals.; (When in the massive state its fresh fracture usually presents changeable colours like some silks, or the plumage of a pigeon's neck.) Jt is occasionally found crystallized in octaedrous, or long, double, triedral pyramids, and tabulated ; often striated. Native bismuth, disseminated as quartz, is found at Lane's mine, in the state of Connecticut. 37. The existence of lead in the native state is somewhat pro- blematical. Mr. Rathkie is said to have discovered it in the island of Madeira, but the lead there found is supposed to have been of volcanic origin; and the occurrence of native lead in lava has been observed elsewhere. 38. Silver is found more frequently pure, or in the state of alloy, than most other metals ; but it is most plentiful in the state of native silver. } The metal is occasionally found in immense masses ; the silver-mines of Kongsberg, Norway, formerly afforded specimens, weighing from 100 to 150 pounds; and in the mine called Nye Forhaabning, one was raised 560 pounds in weight, which is still preserved in the royal cabinet at Copenhagen. Specimens of native silver exhibit a diversity of beautiful forms, such as arborescent, branching, foliated, and moss-like, or in delicate curls like cotton threads. It is also found tooth-shaped, wire- shaped, and sometimes canaliculate and serrated. ,, It likewise occurs imbedded in calcareous spar, |, in prisms crossing each other in all direc- tions. 39. Mercury sometimes occurs native in globules, disseminated in coarse sandstone, and other substances. Crystallized cinnabar, or snlphuret of mercury, is found occasionally sprinkled with globules of metallic mercury. Native amalgams of the metal with silver occur both in the semifluid and solid states. The hydrarguret of silver crystallizes in perfect and modified rhombic dodecaedrous In what state is native copper generally found ? In what condition is native bismuth found ? What peculiarity does its colour present? In what forms does it crystallize ? In what localities has native lead been discovered ? In what condition is silver met with in nature? What remarkable specimens of this metal have been obtained ? What variety of form does it present ? ELECTRO-NEGATIVE SUBSTANCES. 249 and other figures. The plastic nature, of this amalgam is taken advantage of by the Mexican miners to mould figures and ornaments of this substance. 40. Gold is found either in a state of purity, or alloyed with a few other metals, and generally in the latter state, ft occurs in foliations upon quartz, associated with other substances ; but the great bulk of this precious metal in circulation, is principally pro- cured from alluvial strata, where it is met with in masses of various sizes. Pure gold occurs either mas- sive, in detached crystals, as grains in the state of gold dust, or interspersed in brown ironstone, in quartz with needle ore, in den- dritic or arborescent crystals, and in moss- like masses, consisting of delicate inter- woven fibres, as in the marginal figure. In all these states it is found in the gold regions of Virginia, North and South Caro- lina, and Georgia. The alloys of gold are found crystallized in minute cubes and octaedrons, variously ag- gregated in reticular plates and other forms. Auriferous silver, or electrum, is an alloy of a yellowish-white colour, containing gold in various proportions. 41. P latino, occurs in small grains, very heavy, and of a silvery- white lustre. These grains are found in the alluvial strata. With platina are intermixed other metallic bodies, as the alloy of iridium and osmium, in shining foliated grains. Palladium is found in delicate scaly grains, of a lead colour, alloyed with platina. Rhodium is a white metal, which, with platina, iridium, iron, &c., forms a black alloy. Electro-Negative Metallic and Metalloidal Substances, and their Non-Oxidized Combinations. Tellurium and Tellurets. 42. Native tellurium is a mineral gene- rally of a white colour, with a metallic lus- tre,which occurs massive, fine-grained, and disseminated, in the mines of Transylvania. Graphic tellurium occurs of a grayish colour, with a metallic lustre, sometimes tarnished, exhibiting delicate tetraedral and hexaedral prisms, aggregated or in- terwoven on the surfaces of other minerals, so as to have some resemblance to Arabic What is the most common state of native gold ? With what rock is it chiefly associated ? In what soil are the grains and fragments of gold usually met with? How do its alloys commonly present themselves ? In what state does platina occur ? In what situation is it found ? What metals usually accompany it ? Tinder what different appearances does native tellurium occur ? 250 MINERALOGY. or Hebrew characters. This mineral contains a portion of gold, as also does the yellow tellurium. Black tellurium contains lead. 43. Native antimony is found in the mines of Dauphine. It has a white colour like tin, and a granular and foliated fracture : it occurs massive, rarely distinctly crystallized. Antimonial silver, or stibiuret of silver, is found in the Hartz mountains, of a bright white colour, massive, and crystallized in cubes or striated. Anti- mony is also found alloyed with other metals, as nickel and lead. Jlrsenic and Jlrsneiurets. 44. Native arsenic has nearly the colour of tin, but soon becomes tarnished. It exhibits reniform and botryoidal figures. Arseniuret of nickel, commonly called kupfer-nickel, or copper nickel, has the colour of tarnished copper. Arseniuret of cobalt comprises the mineral called gray cobalt, from its steel-gray colour. Arse- niuret of bismuth is found in small brownish globules at Schnee- berg, in Saxony. Carbon and Carburets. 65. This is a mineral which exhibits a great dissimilarity of form and appearance in different states or modes of aggregation. Scarcely any substances can be more unlike in their external cha- racters than the diamond and charcoal, though chemical analysis seems to demonstrate a perfect analogy of composition. Among the minerals which are considered as varieties of pure carbon are diamond, anthracite, and graphite, or plumbago. 46. The diamond exhibits several crystalline forms, as the primitive regular octaedron; the same with solid angles truncated ; with edges truncated, forming the passage into the rhombic dode- caedron; varieties of the latter, giving rise to the hexaedral, pris- matic and tetraedral forms ; cubes with truncated and bevelled edges; and hemitropic crystals or macles. This gem exhibits various colours ; some having a brownish or greenish tint, others are yellow, and there are blue, pink, rose-red, and dark brown diamonds ; but the latter are very rare. Diamonds of a large size are of very unusual occurrence. Among the most remarkable may be mentioned the large diamond in the imperial sceptre of Russia, which was purchased by Catharine II. for the sum of 90,000/. paid down, and an annuity of 4,000/. to the seller ; its weight is 193 carats, and its size nearly that of a pigeon's egg. This gem is considerably exceeded in weight and dimensions by one which belongs to the Rajah of Mattan, in the island of Borneo, where it was found about a hundred years ago. In shape it re- sembles an egg, with an indentation near the smaller end. It is said to be a stone of the finest water : its weight is 367 carats, or In what localities is antimony obtained ? What is the colour of native arsenic ? In what forms does carbon occur in nature ? What variety of external characters is found in the diamond ? What remarkable specimens of this mineral have been found ? SELENION AND SELENIURETS. 251 2 ounces, 169.87 grains Troy. A Dutch governor of Batavia, wishing to purchase this diamond, offered to the rajah, in exchange, 150,000 dollars, two large brigs of war, with their guns and am- munition, together with other pieces of cannon, and a quantity of powder and shot; but the rajah refused to part with the gem, to which the Malays attributed the power of curing diseases, and the possession of other miraculous properties. 47. Anthracite, or kohlenblende, is a carbonaceous mineral, one variety of which is called Kilkenny coal. Anthracite has a semi- metallic lustre, and a conchoidal fracture, and is sometimes slaty, and occasionally columnar. It burns like charcoal, without flame or smoke ; whence in Scotland it is called blind coal. In Penn- sylvania this mineral exists in a great variety of degrees of purity, from that which has 98 per cent, of carbon to that which passes almost entirely into a slaty consistency ; and from the massive, lustrous, compact, jet black anthracite to the almost perfect bitu- minous coal, or the imperfectly converted lignite. It is equally interesting as a mineral deposite and as an article of commerce, being, when pure, unsurpassed as an article of fuel whether for domestic or manufacturing purposes. Graphite, or plumbago, is the well-known substance commonly called black-lead. It is found in England, Scotland, France, Spain, Germany, the United States, and other countries ; but that variety which is most useful for making black-lead pencils, is procured from a mine at Borrowdale, in England. It is said to occur in large, roundish masses, imbedded in a mountain of argil- laceous schistus, traversed by veins of quartz. Selenion and Seleniurets. 49. Selinion appears to be a substance but sparingly distributed in the mineral kingdom. Among its compounds may be noticed the mineral called eukairite, a seleniuret of silver and copper , the seleniurets of lead and copper, which are the products of Swedish mines ; and the combination of selenion with sulphur, occurring in the volcanic regions of Italy. 50. The eukairite is exhibited in the annexed figure. Besides these may be mentioned, the seleniuret of bismuth and tellurium, that of lead and cobalt, the cupriferous sele- niuret of lead, the seleniuret of lead and / mercury, and the .riolite and culebrite, which are seleniurets of zinc with sul- ^ phur and mercury. What value has been attached to these specimens ? What are the characteristics of anthracite ? What is the common name givm to plumbago ? What is the chemical composition of eukairile ? What seleniurets occur in nature ? 252 MINERALOGY. Sulphur and Sulphurets. a. Single Sulphurets. 51. Native sulphur occurs in beds of gypsum or selenite, sul- phate of strontian, and also, though more rarely, in the veins of primitive rocks. 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. Sulphur occurs crystal- lized, massive, and stalactitic. It appears in some warm springs in such quantities as to form a deposit when the water is cooled in contact with air. This mine- ral is often found sublimed, near the craters of volcanoes, as in Italy, Sicily, and South America. Sulphur crystallizes in acute oc- taedrons, the common base of the two pyramids being a rhomboid : also spongeous and granular, and sometimes forming tufted or branching crystals. (See mar- ginal fig.) 52. The metallic Sulphurets are numerous, constituting a large proportion of the ores from which metals are obtained for economi- cal purposes. Sulphuret of manganese, or manganese blende, is found at Nao-- yag, in Transylvania, in the mines of Cornwall, and in Peru. Sulphuret of zinc, or blende, is usually called by the English miners black Jack. The colour of this mineral varies ; some specimens being yellow, some brown, and others black. The first is generally the most pure, the others containing iron, silica arid water, as well as zinc and sulphur. One variety of blende when scratched gives out a phosphoric light. The fibrous blende of Przbram, in Bohemia, contains cad- mium ; and the testaceous or schaalen blende, which has been found at Gerold- seck, in the Brisgau, is a Sulphuret of zinc with iron and a portion of lead. This mineral occurs massive, and in various forms, as octaedrons, tetraedrons, and dodecaedrons, the primitive crystal being a rhomboidal dodecaedron. Some specimens exhibit spicular crystals, as in the marginal figure. The black blende is found at Westches- ter, Pennsylvania. In what situations is native sulphur found ? In what forms do its native masses present themselves ? What are the figures of its crystals ? What name is given in England to the sulphuret of zinc ? With what other metal is this sometimes combined ? SULPHURET OF COPPER. 253 53. Sulphuret of iron, or pyrites, is among the most abundant mineral products in various parts of the world. Large crystals of this substance have been met with in the sepulchres of the Incas of Peru, and they are supposed to have been used as mirrors. No- dules or globular masses are sometimes found in chalk. Its primitive form is the cube ; but it oc- curs variously crystal- lized, as in the annexed figure. 54. Radiated pyrites (a variety frequently including the lenti- cular or coxcomb, and the globular pyrites) is very liable to spontaneous decomposi- tion and inflammation, sometimes pro- ducing mischievous consequences in mi- neralogical cabinets. Magnetic pyrites occurs massive, foliated, and crystallized in hexaedral prisms. Pyrites exhibits a metallic appearance, much resembling brass or pinchbeck. 55. Sulphuret of cobalt is seldom found crystallized, occurring massive and disseminated. Its colour is pale *eel-gray ; when tarnished, reddish ; and it yields a sulphureous vapour when heated. The mines of Tunaberg and Bastnaes, in Sweden, afford cobalt pyrites. 56. Sulphuret of nickel, formerly supposed to be native nickel, till its composition was ascertained by Arfvedson, occurs in the capillary form, or that of long, wire-shaped crystals, of a brass- yeliow tint, tarnished. 57. Sulphuret of copper is the most common ore of that metal, including some varieties. It is found in several forms as compact, foliated or crystallized, the primitive form being an acute octaedron, with a square base. (See marginal figure.) One variety is the malleable copper ore, peculiar to Siberia : the colour said to be a shining steel-gray. What is the primitive form of the sulphuret of iron ? For what purpose does the lustre of this substance allow it to be used ? What occurs when radiated pyrites is exposed to the air? How do we find sulphuret of cobalt ? What is the appearance of sulphuret of nickel? In what combination does copper most frequently present itself? 254 MINERALOGY. The sulphurets, called yellow copper and copper pyrites, contain much iron, as well as copper and sulphur. Variegated or peacock copper ore, which is of this kind, exhibits fine iridescent colours. Among the sulphurets of copper may be reckoned the secondary fossils, styled Frankenberg corn-ears, which are found in bitumi- nous marl-slate, at Frankenberg, in Hesse ; and are chiefly com- posed of vitreous and gray copper. Tennantite, found in copper mines near Redruth, in Cornwall, appears to differ from gray copper ore, in containing more sulphur and less iron, and in pos- sessing greater hardness. 58. Sulphuret of lead, or galena, is the most important, as well as the most common of the ores of this metal, constituting the principal source from which it is obtained. It usually contains silver, in addition to lead and sulphur. It occurs in extensive beds and veins, in primitive and secondary rocks, most abundantly in argillaceous schist and secondary limestone ; and it is acom- panied by the ores of zinc, copper, iron and silver ; and by quartz, sulphate of barytes, carbonate of lime, and fluoride of calcium, (fluorspar.) Much of this ore is obtained from the mines of Missouri, where it is found massive, or crystallized in cubes and regu- lar octaedrons, sometimes of gigantic size. The peacock lead ere of the miners displays various purple tints, like a dove's or pea- cock's neck. A compact and specular variety is styled by the Derbyshire miners " slickenside." Blue lead ore, crystallized in hexagonal prisms, is found at Huelgoit, in Bretagne. Anti- moniated galena, of a tin-white colour, aggregated crystals, contains, besides lead and sulphur, a large portion of an- timony. 59. Sulphuret of bismuth, or bismuth glance, occurs massive, or in delicate acicular crystals. Cupreous bismuth ore is a sulphuret of bismuth and copper, which is found massive and dissemi nated. Needle ore, a sulphuret of bismuth, lead and copper, which derives its appellation from its wire-like appearance, occurs imbedded in quartz. 60. Sulphuret of tin, or tin pyrites, also called bell-metal ore, from its colour, is a compound of sulphur, tin, and copper, with a small portion of iron. 61. Sulphuret of mercury exhibits some diversity of colour and form. There are two varieties, sinnabar, and hepatic mercurial ore, the former of which is divided by Werner into the dark red cin- nabar, the colour of which approaches that of cochineal ; and the What other metal is sometimes mixed with the sulphuret of copper? What is the common name of the sulphuret of lead ? In what kind of rock is it generally found ? What is meant by cupreous bismuth ? What by needle ore ? What is the true composition of tin pyrites ? What name is commonly given to the sulphuret of mercury ? COMPOSITE STJLPHURETS. 255 bright red or native vermilion. The hepatic mercurial ore, or liver ore is a mixture of cinnabar with bituminous and earthy matter compact and slaty, found in the m ' nes f Idria. Coral ore is of the same nature, with petrifactions. This sulphuret occurs disseminated and superficial, form- * n aroorescent figures on clay-slate, &c. (See marginal figure.) 62. Sulphuret of silver, or vitreous sil- ver ore, occurs massive, or crystallized in cubes, octaedrons, and dodecaedrons, besides other forms. Black silver ore is a pulverulent variety of this sulphuret, having a scoriaceous, sooty appearance ; sometimes massive, or coating native silver. 63. Sulphuret of antimony, occurs compact, foliated, radiated, or plumose; composed of downy fibres, disposed in nests, or fas- cicu ] ar crystals. (See marginal figure.) Some varieties exhibit a fine iridescent blue, yellow, and red tarnish. 64. Sulphuret of arsenic, when it contains a large proportion of sulphur, constitutes the mineral called orpiment, characterized by its bright yellow colour ; with a less proportion of sulphur, arse- nic forms realgar, or red orpiment. The latter is said to occur chiefly in primitive rocks, but the yel- low orpiment in the secondary or floetz rocks of Werner; and both are found near volcanos. These minerals are sometimes massive, or lamellated ; and occasionally, but more rarely, crystal- lized. 05. Sulphuret of molybdena is a sectile, shining substance, re- sembling plumbago, and generally massive or laminated ; rarely crystallized. It is found in Sweden, Bohemia, and near Mont Blanc, disseminated in a gray granite. It has also been met with in Cornwall, and in Inverness-shire, North Britain. b. Composite Sulphurets. 66. Sulphuret of arsenic and iron, arsenical pyrites, or mispickel, occurs principally in veins in primitive mountains, and is common in the copper mines of Cornwall. It is often iridescent. Some varieties are argentiferous, and exhibit a tarnished silver hue. What is the true character of black silver ore? What is the appearance of sulphuret of antimony? What is the chemical character of orpiment and realgar ? What peculiar properties belong to sulphuret of molybdena? In what localities has it been found ? To what triple compound is the name arsencial pyrites applied ? 256 MINERALOGY. Glance cobalt is an arsenio-sulphuret of co- balt, which is found massive, and crystallized in cubes, octaedrons, dodecaedrons, and va- rious other derivative forms. 67. Among the composite sulphur salts may likewise be mentioned the bournonite (so called from its discoverer, Count Bournon,) which is a sulphuret of lead, antimony, and copper, crystallized in tetraedral prisms, va- riously modified. 68. Red or ruby silver ore is distinguished into two kinds, the dark red and the light red, both crystallizing in hexaedral prisms ; but the former is a sulphuret of silver and antimony, and the latter a sulphuret of silver and arsenic : there are also other varieties. Gray copper ore, or fahlerz, is a double sulphur salt, of copper and antimony. Oxides of the Electro-Positive Metals. 69. The oxides of manganese occur in considerable variety, and are very generally disseminated. Fibrous gray manganese crystallizes in delicate acicular crystals, and other varieties are radiat- ed, foliated, or compact, the latter sometimes in botryoidal masses. f]arthy gray man- ganese is much used in the preparation of oxygen gas. Fibrous black manganese is found dendritic, on the sur- face of stone, or indurated marl. (See marginal figure.) Wad is often ochreous, of a brown or black colour. Sulphuretted oxide of manganese, which resem- bles the gray oxide, is found with the ores of tellurium, at Nagyag, in Transylvania. Franklinite, is an oxide of manganesewilh zinc and iron. 70. The oxides of iron are extremely numerous. Specular oxide, or iron glance, found in the Isle of Elba, is remarkable for its beautiful iridescent or changeable colours ; and specimens from Stromboli and Vesuvius occur in large lamellar crystals, often imbedded in lava, looking like polished steel. Iron mica is found in delicate, bright, hexaedral, tabular crystals, of an iron-gray colour. Red iron ore includes the varieties of compact red iron- stone, and red haematite, the latter in large masses, uniform, or mammillated. Magnetic ironstone, or oxidulated iron, is very common, both massive and crystallized, in octaedrons. Wootz, What is meant by glance cobalt? What is the composition of bournonite ? What is the nature of ruby silver ore ? For what is the earthy grey manganese employed ? What is Franklinite ? For what is the iron ore of Klba remarkable? What varieties does the red iron ore embrace? OXIDE OF URANIUM. 257 or Indian steel, is obtained from an ore of this kind, found in the East Indies. 71. Hydrous oxide of iron, ^or brown ironstone, occurs in several varieties, as the micaceous, called goethite, forming 1 trans- parent tables, of a blood red hue ; that in fine scales, lining the cells or vesicles found in lava ; in the state of a dark brown powder, used by the Booshuanas of South Africa, as hair-powder ; the fibrous brown ironstone, or brown haema- tite, in silky fibres, or zoned, at- tached to the roofs or walls of ca- verns ; the compact brown iron ore, and brown ochre. Argillaceous, or clay ironstone, occurs in nodules, reniform masses, bc. (See marginal figure,) and some specimens exhibit impressions of ferns and other vegetables. 72. Among the oxides of copper is the native protoxide, or ruby copper ore, which occurs massive\and crystallized in octaedrons and other figures : and there is a variety found in Germany in beautiful bright red capillary crystals. The tile ore, a compact earthy variety, is a mixture of ruby copper and brown iron ochre. 73. Oxide of lead, or native minium, supposed to be produced from the decomposition of galena, has been found in the lead- mines of Yorkshire, England, and on the continent of Europe. Yellow oxide has been obtained from Siberia ; and an ash-gray variety, coating galena, is said to have occurred in North Wales. Plomboromme, so-called from its appearance, is a compound of lead with oxygen, alumine, and water, of a shining yellow colour, and mammillated. 74. Oxide of bismuth, or bismuth ochre, is a light yellowish-gray or greenish mineral, earthy and friable, which is found in Saxony and Bohemia. Oxide of zinc, called red oxide, from its colour, occurs dissemi- nated in groups, indeterminately crystallized, or of a lamellar structure, in iron-mines in New Jersey. Oxides of cobalt. The black, brown, and yellow cobalt ochres, appear to be hydrates, or combinations of water with the oxides of cobalt and manganese, frequently mixed with oxide of iron, v Oxide of uranium, called uran ochre, exhibits various shades of yellow. ;Pechblende is a ferriferous oxide of uranium, containing also lead, copper, arid other substances. Whence is Indian steel obtained ? In what variety of forms does brown ironstone occur? What is the appearance of clay iron-stone ? What organic substances does it occasionally contain ? How is the oxide of copper crystallized? What is the chemical nature of minium ? What is plorabgomme? W r here is native oxide of zinc found ? What is the nature of cobalt ochres? What is Jhe nature of the mineral called pechblende ? 258 MINERALOGY. 75. Oxide of tin includes common tin ore and wood-tin. The former occurs massive, variously crystallized, and disseminated in granite ; it also forms delicate capillary crystals. /Wood-tin has been found only in Cornwall and in Mexico; its structure, in general, is fibrous, having the appearance of wood, but extremely heavy. A variety, called in Cornwall toad's eye wood-tin, ex- hibits globular concretions of radiating fibres, disposed concentri- cally in brown and yellow colours. Oxides and Oxacids of Electro- Negative Substances, with their Com- binations. Alumina and Aluminatts. 7G. The oxide of aluminum, which constitutes in its pure state aluminous or argillaceous earth, sometimes occurs alone in a crystallized form, and sometimes acts the part of an acid, entering into combination with the oxides of other bodies. Among the varieties of native alumina, are the perfect corundum, which is found of different colours. The blue kind is the gem called the oriental sapphire, the purple the oriental amethyst, the yellow the oriental topaz or chrysolite, the green the oriental emerald, and the red the oriental ruby. The adamantine spar, or imperfect corundum, and emery, are also chiefly composed of alumina, containing only very inconsiderable portions of silica and oxide of iron. Fibrolite, (called, by Lucas, bournonite,) according to an analysis of Che- nevix, consists principally of alumina arid silica. The indianite of Count Bournon is a granular mineral from the carnatic, con- taining specks of hornblende, and it is one of the matrices of the common corundum. Diaspore and gibbesite are hydrates of alumina. 78. The aluminate of magnesia occurs in the spinel or balas ruby, consisting of red octaedral crystals, and there is a blue kind of spinel found in Sudermania, in Sweden. Ceylonite or pleonaste, which has been reckoned a variety of the spinel, according to Ekeberg, contains iron as well as alumina and magnesia. The automalite or gahnite,found in Sweden, and in New Jersey, has been termed the zinc spinel, being a combination of alumina with oxide of zinc. Plombgomme, already mentioned, is a hydrous aluminate of lead. Silica and Silicates. 79. The oxide or acid of silicon, and its combinations with the oxides of other bodies, form by much the most numerous division What are the forms and localities of wood tin? What is the nature of corundum ? Into what precious stones does alumina enter as a chief ingredient ? What is emery ? What is the chemical composition of spinel ? What office does the alumina perform in composing this mineral ? What is meant by zinc spinel ? ROCK-CRYSTAL AN 7 D QUARTZ. 259 of mineral substances. In previous arrangements the siliceous minerals have in general been considered as constituting so many distinct species, but they may with more propriety be regarded as merely varieties, whose peculiar external characters are respec- tively derived from the admixture of extraneous substances, or from other circumstances connected with their formation. 80. Rock-crystal, which is composed of pure siliceous earth, crystallizes in various forms, the primitive crystal, which is of rare occurrence, being an obtuse rhomboid. Sometimes it appears in hexaedral pyra- mids, with aeicular diverging fibres, as in the marginal figure. Very fine specimens, and some of extraordinary size, are found in Madagascar, and among the Alps. 81. Amethyst quartz is tinged with a little iron and manganese. Rose quartz derives its roseate hue from manganese. Red quartz, in small crystals, coloured by iron, has obtained the name of hyacinth of compostella. Other varieties are fibrous quartz; flexible sand- stone, found in Brazil, and at Mount St. Gothard, in Switzerland ; stalagmitic quartz, or quartz-sinter, including the siliceous concre- tions formed by deposition from the hot springs of Geyser, in Ice- land ; pearl-sinter, or fiorite, from the hill of Santa Fiora, in Tus- cany, and from the Isle of Ischia; ceraunian-sinter, or fulgurite, supposed to have been formed by the action of lightning; iron, flint, or ferruginous quartz, containing small quantities of iron; and hyalite, which contains water combined with silica. Prase, or green quartz, contains actinolite. 82. Avanturine is a beautiful kind of quartz, of a rich brown colour, exhibiting interspersed glittering particles, either from the presence of minute scales of mica, or from the occurrence of abundance of small fissures, which cause numerous reflections of the rays of light; and the cat's-eye, chiefly from Ceylon, displays an opalescent lustre, owing to almost invisible fibres of amianthus imbedded in the quartz. Hornstone is of two kinds, called con- choidal and splintery, from the mode of fracture ; its most usual colours are reddish-white, milk-white, and very light gray, some- times stained with dull yellow ; and the splintery hornstone occa- sionally is marked with small irregular spots, supposed to be owing to the presence of chlorite. What elementary principles are the most abundant in the mineral king- dom? What is the substance commonly known as rock crystal ? What is its primitive form? Enumerate some of the varieties which occur in this substance. What peculiar appearance is exhibited by avanturine? 260 MINERALOGY. 83. Common flint exhibits a vast variety of singular forms and appearances, most of which seem to be derived from organic bodies. Calcedony occurs of different colours, as pale blue, gray, and sometimes, but more rarely, of a light green hue ; it is crystallized in obtuse rhomboedrons ; speci- mens of botryoidal calcedony are found in the Ferroe Islands; and nodules inclosing water (enhydrites) in volcanic rocks, at Monte Berico, near Vicenza, in Italy. Some specimens exhibit curious dendritic and other figures on the surface, of a red or black colour; they are called mocha stones, and are used for the covers of snuff- boxes, and for ornamental purposes. 84. Cornelian is distinguished from calcedony merely by its colour, being red or yellow, and sometimes striped. Plasma is of a dullish green colour, often spotted with white. Heliotrope is a mix- ture of calcedony with green earth, occasionally containing particles of red jasper interspersed, whence it is styled blood- stone ; some varieties are yellow spotted and semi-transparent. Chrysoprase is a beautiful variety of calcedony, which owes its apple-green colour to oxide of nickel. Pimelite is a similar green siliceous earthy mineral, which, according to Klaproth, contains a large proportion of water. Agates are siliceous compounds of an analogous nature, displaying variety of colour, diversified by curved and angular lines, forming multitudes of singular and beautiful figures. Hence their several designations of striped, zoned, fortification, landscape, moss, spotted, and clouded agates. 85. The jaspers form a multifarious division of siliceous minerals. The globular or Egyptian jasper, of various shades of red, is found at Cairo, in masses supposed to be formed by infil- tration ; riband or striped jasper, generally of a brownish-red, with green bands, occurs in Siberia; agate jasper, found only in veins of agate, exhibits a diversity of colours, red, white, and yel- low ; porcelain jasper, which has a vitrified appearance, is pro- duced by the operation of subterraneous heat on clay-slate. 86. Opal is inferior in beauty of appearance to few minerals, being distinguished by a peculiar chatoyant lustre or play of colours, arising from a multiplicity of minute and otherwise im- perceptible fissures withfh its substance. These are the noble opals, the finest specimens of which are found in Hungary. The gyrasol, or fire-opal, from Mexico, displays usually reddish, yel- lowish, and greenish tints, with a flame-like iridescence, depend- What are the varieties of oalcedony ? What is signified by the term enhydrite? What is heliotrope? What is the composition of agates ? What variety of jaspers may be enumerated ? SILICATES. 261 ing on interior fissures. The common opal and the semi-opal are destitute of the play of colours which characterizes the noble opal. Hydrophane, or oculus mundi, is white and opaque when viewed in the air, but is rendered transparent by immersion in waler. Wood-opal is found of various colours, generally bright yellow, and its appearance betrays its nature, as opalized wood. Jaspopal exhibits red, brown, and yellow colours, and is sometimes spot- ted. Menilite, so called because it is found at Menil-Montant, near Paris, is nearly allied to common opal. All the opals are regarded as hydrates of silica. Silicates with a Single Base. 87. Table-spar or wollastonite, found at Mount Vesuvius, Nagyag in Transylvania, and elsewhere, is a silicate of lime. The silicates of magnesia are more numerous, including steatite, which is white, or mottled like soap, and of various colours, the yellowish-green variety being among the most remarkable; kef- fekil or meerschaum, of which pipe-bowls are manufactured; keffekillite, found in the Crimea; lithomarge, sometimes of a red- dish-yellow colour, and sometimes of a purple hue, but more fre- quently white. 8S. Silicate of zinc, called likewise electric or siliceous calamine, is obtained from Hungary and Siberia. Silicate of manganese occurs in varieties, which have been distin- guished by different names, as allagite and rhodonite. Silicate of cerium, or ceritc, found at Bastnaes, in Sweden, con- tains yttria as well as oxide of cerium, and therefore belongs to the next division. The silicates of iron include the hisingerite, the sideroschizolite, and the chlorophaeite. The silicates of copper are crysocoll, siliceous malachite, or mountain-green, which contains, according to Klaproth, carbonic acid, as well as silica, and water ; and dioptase, or copper emerald, a scarce mineral from Siberia. 89. ^ilicate of zirconia includes the common zircon, and some hyacinths from Ceylon, and other countries ; besides the variety called zirconfte, and the blue zircon from Mount Vesuvius. Among the silicates of alumina are the kyanite or disthene, and its varieties, the bucholzite, and the sillimanite. The hydrous silicates of alumina, or those containing water, exhibit considera- To what is the play of colours in the "noble opal" attributed ? What peculiarity is possessed by the hydrophane '. What is the chemical nature of this class of minerals? What is meant by the term silicate 1 (See Chemistry No. 309.) What use is made of the silicate of magnesia called keffekil I Where is silicate of zinc found ? What different varieties of silicate of copper exist? What is the composition of sillimanitc ? 262 MINERALOGY. ble variety, including some kinds of lithomarge, fuller's earth, bole, cimolite, haloisite, &c. Finite occurs crystallized in equiangular, hexagonal prisms, of a blackish-green colour, imbedded in granite ; and gieseckite, found in Greenland, appears to be a variety of this mineral. b. Silicates with Several Bases. 90. Apophyllite is a hydrated silicate of lime and potash; me- sotype, or needle zeolite, is a hydrated silicate of alumina, lime, and soda, occurring in acicular tetraedral crystals, as in the follow- ing figure ; natrolite contains alumina and soda, but no lime ; and pcolicite and thomsonite are hydrated silicates of alumina and lime. Analcime is a silicate of alumina and soda with a small quantity of lime. Stilbite is a hydrated sili- cate of alumina and lime, containing (accord- ing to Gehlen) a little soda. Lanmontite, so called in honour of M. Gilles Laumont, who discovered it in the lead-mines of Bretagne, differs from the preceding in containing no - ; ^ soda, but some carbonic acid ; it is subject to efflorescence when exposed to the air. Here may be mentioned obsidian, of a black or smoke-gray hue, massive, with a conchoidal fracture ; pitchstone, green, reddish-brown, or nearly black, like pitch ; and pearlstone, of a dark bluish-gray colour, massive, but having a granular ap- pearance, with a shining lustre. 91. Among the zeolitic substances may also be mentioned prehnite, of which there are two principal varieties, the radiated or fibrous, which is of a green colour, and the foliated, in thin tabular crystals, of a greenish- white colour ; both consisting principally of silica, alumina, lime, oxide of iron, and water, hf which last body the foliated prehnite contains but a minute quantity ; comp- tonite, a volcanic substance, found lining the cavities in lava ; gmelinite, or hydrolite, and levine. In the same family fe to be reckoned the harmotome, or cross stone, which haVrtceived the latter name from the peculiarity of its crystallization, and which consists of silica, alumina, barytes, and water ; and the potash harmotome, which includes the Vesuvian minerals, styled zeago- nite, gismondine, and abrazite. 92. To the feldspar family belong several important mineral Enumerate some of the minerals in which silicic acid is combined with several bases. What is the appearance of obsidian? of pitchstone ? of pearlstone ? What appearance has prehnite? What is the composition of cross stone ? HORNEBLENDE. 263 bodies. Common feldspar is found ex- hibiting a diversity of colours, as white, gray, light red, green, and blue, crys- tallized in rhombic prisms, variously modified, imbedded in granite. Labrador feldspar is found massive and compact, displaying a beautiful variety of opa- lescent colours. Among the feldspathic minerals are adulari, or naker feldspar ; cleavelandite or albite, containing soda ; leucite, or amphigene ; and spodumene or triphane, and petalite, both aluminous silicates of the alkali called lithia. Nepheline, eleeolite or fettstein, and wernerite, which includes the meionite of Vesuvius, scapolite, paranthine, and dipyre, are minerals more or less of an analogous nature. The feldspars are silicates of alumina, lime, and potash. 93. The micaceous and talcose minerals form an interesting di- vision of substances. Mica exhibits many varieties, which, with reference to their chemical characters, have been divided into potassa-mica, which is by much the most common ; magnesia- mica, found at Mount Vesuvius, and at Munroe, in the state of New York ; and lithia-mica, or lepidolite, sometimes of a beautiful peach-red colour. Talc is found in considerable variety, as the Venetian talc, in foliated crystals of a greenish-white colour, a substance which forms the basis of rouge, used as a cosmetic ; in- durated talc ; and agalmatolite, (talc graphique of Haiiy,) a sectile mineral, which the Chinese form into cups, images, or other figures. Chlorite is a green mineral, crystallized in aggregated small modified rhombic prisms ; and there are earthy and foliated varieties. 94. Among the amphi- bolic minerals, or those of the hornblende family, may be noticed the com- mon, the basaltic, and the schistous hornblende; the antinolite, or strahlstein, divided into the glassy, the common, and the fibrous varieties ; the tre- molite, or grammatite, common and glassy ; the arfvedsonite ; and the an- thophyllite, which con- tain silica, magnesia, and What are some of the varieties found in feldspar ? What bases are conlained in feldspar? What are the chemical varieties found in mica and talc ? What differences ot colour and crystalline form do minerals of this class pvhibit? What are some of the most important of the hornblende family of minerals ? 264 MINERALOGY. oxide of iron or lime ; and most of them likewise contain alu- mina. 95. Serpentine, of which there are the noble and common varie- ties, exhibits various colours, green, brown, and red, often inter- mixed ; and serpentine-marble is ornamented with waving lines, as represented in the preceding figure. Chrysolite and olivine, like serpentine, are coloured by oxide of iron. 90. The asbestine minerals in their chemical composition are re- lated to the preceding. Among the most remarkable iprieties may be mentioned, the flexible asbestus, or amianthus, used in making incombustible cloth ; mountain wood, rock cork, and the blue and yellow asbestus, from South Africa, called krokydalite. 97. The pyroxenic minerals are numerous, including augite, found in small black crystals, imbedded in lava, the granular variety of which is called coccolite ; diopside, including the mussite and the alalite,from Piedmont ; the pyrgomme, or fassaite, which differs from augite in the form of its secondary crystals; and the achmite. To these may be added the diallage, or schiller- spar, of a green, brown, or black colour, and having a metallic lustre ; the bronzite, having much the colour and lustre of bronze; and the hypersthene, tinted with a mixture of brown, black, and copper colour, and exhibiting considerable metallic lustre. 98. The epidote is a mineral of a green colour, massive or in large crystals, containing silica, alumina, lime, and oxide of iron ; and some varieties also afford oxide of manganese. Zoisite re- sembles epidote in its chemical constitution, but it is generally of a bluish or yellowish-gray colour. Idocrase, or vesuvian, is of the colour of brown resin, and of a shining lustre, and is found in prysmatic crystals, among substances ejected from volcanos ; and of a similar composition is the hessonite, or cinnamon-stone ; both these minerals containing silica, alumina, lime, and oxide of iron. Cyprine is a variety of the idocrase, tinted blue by the oxide of copper. 99. The garnet family contains numerous and diversified varie- ties, which are silicates of alumina, tinged with oxide of iron or other metals. The pyrope, or chrome garnet, of a dark cherry-red colour, occurs in rounded and angular concretions, and likewise imbedded in serpentine and other rocks ; the colophonite, so named from its resembling resin in colour and lustre, contains oxide of manganese, and a minute quantity of oxide of titanium ; the melanite, or black garnet, according to Klaproth, is an alumi- nous silicate of lime and iron, with a trifling proportion of oxide of manganese ; the grossular, or wilui garnet, so called from the resemblance of its yellowish-green crystals to a gooseberry, is nearly of similar chemical composition ; the allochroite, or splintery garnet, is not so hard as quartz, but strikes fire with steel, and What appearance is exhibited by serpentine ? Enumerate some of the varieties of pyroxenic minerals. What materials enter into thf composition of epidote? Where is idocrase found ? What, is the colouring matter of garnets ? Whence does the colophonite derive its name ? EMERALD. 265 melts before the blowpipe into a black enamel ; it contains oxide of manganese, as well as oxide of iron, in considerable proportions $ and analogous to these is the romanzovite. 100. The gehlenite, so called from Professor Gehlen, an eminent mineralogist, is found in square prismatic crystals, of a light gray, olive-green, brown, or bluish-black colour. The iolite, or'dichroite, is so called from its different appearance when viewed in different positions, generally exhibiting a dull violet, or indigo colour ; but if viewed by transmitted light, in the direction of the axis of the crystals, it appears of a pale yellowish-brown, or gray hue; and it occurs massive, or crystallized in hexaedral prisms: according to the analysis of Dr. Leopold Gmelin, it is an aluminous silicate of magnesia and oxide of iron, with small quantities of lime and oxide of manganese. Karpholite is a mineral of a deep straw colour, in radiated fibres or tufts ; it has only been found at Schlackenwald, in Bohemia, and it appears to be a hydrated silicate of alumina, and the oxides of iron and manganese. 101. Staurolite, cross-stone, or granatite, is a bisilicate of alumine and oxide of iron. Among the silicates containing 1 yttria and protoxide of cerium are the gadolinite, a very dark green mineral of a shining lustre, as hard as quartz, found at Ytterby, in Sweden ; allanite, a brown- ish, shining mineral, from Greenland ; cerite, of a reddish-brown or crimson colour, found massive and disseminated ; orthite, which resembles gadolinite, but occurs in thin veins in granite, and con- tains, besides yttria and oxide of cerium, oxide of manganese, alumina, lime, and water ; and the variety called pyrorthite, which inflames before the blowpipe, containing one-fourth of carbon. 102. The silicates, containing oxide of glucinum, (glucina,) constitute a division of gems, including the emerald. The emerald is found chiefly in Peru, crystallized in regular hexaedral prisms, of a fine green colour, which it derives from oxide of chrome. The beryl occurs in primitive rocks in various parts of the world, but especially in Siberia, resembling in the form of its crystals the emerald, but of a pale green or blue colour, containing oxide of iron, instead of oxide of chrome. Very large beryls have been found at Limoges, in France, and at Ackworrh, in New Hamp- shire ; some crystals weighing more than fifty pounds. The euclase is a very scarce mineral, found in Peru and Brazil, of a pale or bluish-green colour, crystallized in rhombic prisms ; and, according to Berzelius, consisting' entirely of silica, alumina, ancl glucina. The chrysoberyl, or cymophane, occurs crystallized in tetraedral prisms, and variously modified, of a pale yellowish- green colour; and it is an aluminons silicate of lime, coloured by oxide of iron. What peculiar appearance is exhibited by the dichroite ? What is its chemical composition ? What are the characters of gadolinite ? What peculiarity belongs to pyrorthite ? Wliere is the emerald found ? In what localities is the beryl found ? 266 MINERALOGY. 103. Lazulite, or lapis lazuli, is the mineral which furnishes the pigment called ultramarine ; according to an analysis of Kla- proth, it contains silica, alumina, lime, sulphate of lime, and oxide of iron, to which last it was supposed to owe its azure colour; but it appears, from the more recent researches of Gmelin, that ultra- marine is a double silicate of alumina and soda, coloured by com- bining with sulphuret of sodium, and it has accordingly been artificially manufactured in France, in large quantities. Lapis lazuli is found in rolled pieces, in various oriental countries. Ha; yne, or latialite, is a mineral of somewhat analogous compo- sition, containing, according to Vauquelin, silica, alumina, lime, and sulphate of potash, with a small quantity of oxide of iron, and a considerable proportion of some volatile matter. It exhibits various shades of blue, and is found imbedded in basaltic and feldspathic rocks, in granular c6ncretions, and also crystallized in rhombic dodecaedrons. 104. Sodalite, so named from its containing a large "proportion of soda, amounting to a fourth part of the mineral, is of a dark green colour, massive, or crystallized in rhomboidal dodecaedrons, imbedded in white feldspar. It has only been found in West Greenland, and since on Mount Vesuvius. Eudialyte is a silicate of soda, lime, and zirconia, with oxide of iron, oxide of manganese, muriatic acid, and water. 105. The tourmalines and schorls, with their varieties, might be placed with the borates, as they contain boracic acid. The rubellite is a beautiful variety of the tourmaline, cf a pale pink colour, sometimes imbedded in quartz. One of the finest speci- mens known of this mineral, in which the crystals are arranged in a radiated form, is preserved in the British Museum. There are also red and blue varieties of the rubellite, chiefly from Massa- chusetts, and from Siberia; flesh-coloured tourmalines are found at Rozena, in Moravia ; to which may be added the dark green variety, called the Brazilian emerald ; and the asparagus green in dolomite, from Campo Longo. 106. Common schorl occurs in black acicular crystals, distinct and aggregated, imbedded in quartz or feldspar. Black schorl is, in various forms, found abundantly disseminated through the granites. A specimen of green tourmaline, analyzed by Gme- lin, was found to contain, be- sides silica and alumina, oxides of iron and manganese, boracic acid and lithion ; red tourmaline was found to be an aluminous What is the constitution of lapis lazuli ? What advantage has arisen from an accurate analysis of this mineral? In what situations is latialite found ? What is socialite and eudialite ? In what class of bodies are we to place the tourmalines and schorls ? What constituents did Gmelin find in green tourmaline ? TITANITE. 267 silicate of potash, and oxide of manganese, with boracic acid and lithion ; and black schorl contains silica, alumina, potash, soda, oxides of iron and manganese, and boracic acid and magnesia. Axinite is a mineral of somewhat analogous composition, contain- ing silica, alumina, lime, and the oxides of iron and manganese. It occurs in thin flat crystals, the primitive form of which appears to be a right prism with a rhombic basis, of a clove-brown colour, sometimes very pale, and sometimes approaching to gray. Beauti- ful large transparent crystals are found at Bourg POisans, in Dauphine, in France. 107. The topaz family constitutes an abundant division of the minerals, containing silica and alumina: and from the large pro- portion of fluoric acid, which they also generally afford, they might perhaps, without impropriety, be reckoned among the fluorides. The characteristic colour of the topaz is yellow, but this gem is also found pink, blue, or colourless. It is found crystallized, in rhombic prisms, with pyramids, variously modified, and its cross fracture is always foliated. The topaz is said to be the most widely distributed among the precious stones, occurring not only in Brazil, but also in New South Wales, in Siberia and various other parts of Asia, in Saxony, in Scotland, and at St. Michael's Mount, in Cornwall. 108. The pyrophysalite is found of a greenish-white colour, in irregular prisms, imbedded in quartz. The pycnite, formerly con- sidered improperly as a variety of the beryl, occurs in thin, pris- matic concretions, which are sometimes hexagonal, exhibiting either a pale lilac, a sulphur yellow, or a light straw colour. These two last mentioned minerals, like the topaz, are compounds of alumina, silica, and fluoric acid. Oxide of Titanium and Titanates. 109. Titanium is found in the state of oxide in various parts of the world, either in alluvial strata, or imbedded and crystallized. Rutile, or rutilite, also called titan schorl, is a brownish-red mine- ral, with a semi-metallic lustre, which occurs massive, and in rhom- bic tetraedral prisms ; it is also found in capillary crystals, often curved, and crossing each other in all directions. Acicular and ca- pillary crystals of rutile have been found inclosed in rock-crystal, in Brazil and elsewhere. This mineral appears to consist of per- oxide of titanium. Anatase, or octaedrite, which is found in blue or party-coloured long octaedral crystals, at Bourg 1'Oisans, ge- nerally associated with quartz and adularia, is a protoxide of tita- nium. 110. Sphene, or titanite, is a combination of the oxide of tita- What is the composition and character of axinite ? What two ingredients constitute the chief part of the topaz minerals? What is the composition of pyrophysalite and pycnite ? What in the chemical nature of rutilite ? of anatase ? 268 MINERALOGY. nium with silica and lime, which occurs imbedded in very oblique tetraedral prisms, with diedral terminations, wedge-shaped in each direction. Among the varieties of this mineral are those call- ed brown and yellow menachan ore, in large crystals, found at Arendahl, in Norway ; and pale green crystals, containing chlo- rite disseminated through them from Mount St. Gothard. Pyro- chlore, from Fredriksvarn, in Norway, is a compound of titanate of lime with titanate of uranium. Nigrine is of a velvet-black colour, and is found in rounded and angular grains, having a semi-metallic lustre. Iserine and menachanite have the appear- ance of black sand, slightly magnetic. These three last men- tioned minerals appear to consist chiefly of the oxides of titanium and iron ; though, according to Dr. Thomson, iserine contains also a considerable proportion of silica, with some alumina and oxide of uranium. Crichtonite is a silicate of titanium, which is found in small, black, shining crystals with anatase. Columbic Add and Columbates. 111. Tantalite, or columlite, is a mineral of a black colour, which crystallizes in oblique rhomboidal prisms, and which is very rare, having only been found in North America and in Bava- ria. It appears to consist of the oxides of columbium, iron, and manganese. Yttrotantalite, found at Ytterby, in Sweden, is com- posed of oxide of columbium, yttria, and iron. Among the mine- rals which contain the oxide of columbium are also the finbo and the brodbp-tantalites of Berzelius. Antimonic Oxide or Jldd^ and rfntimoniates. 112. Among the oxides of antimony are antimony ochre, a straw-coloured mineral, often coating grey antimony, which eva- porates before the blowpipe without melting ; and white antimony which occurs in tetraedral flat crystals, or in tufts of delicate fibres, on quartz, galena, &c. Red antimony, found in fine capilla- ry crystals, stellated, of a red or tarnished purple colour, is a combination of the oxide of this metal with the sulphuret ; and an argentiferous variety, of a fibrous texture, and reddish-brown co- lour, called tinder ore, is found in the Hartz mines, in Germany. Tungstates. 113. Tungsten is found only in such a state of union with oxy- gen and other bodies, as to constitute mineral salts called tung- What is the composition of sphene? What compound of titanium is found in Switzerland ? What ingredients enter into the mineral iserine? Where is columbite found ? What oxides of antimony are found in nature? Where is tinder ore obtained ? CHRCMATE OF LEAD. 269 states ; the compound of this metal with oxygen, as it occurs natu- rally, having the properties of an acid, and, as such, entering into combination with the oxides of certain other metals. 114. The tungstate of lime (scheelin calcaire of Hauy,) alsf> na- named scheelite or tungsten, and, from its great specific gravity, heavystone, is a whitish or yellowish-brown mineral, which is found massive, or crystallized in octaedrons, coating other sub- stances, in England, France, Saxony, Bohemia, and Sweden. Spe- cimens of the primitive (octaedral) crystal of this metallic salt are obtained at Allemont, in Dauphine. The tungstate of iron and manganese called wolfram, occurs in the massive form, or crys- tallized in tetraedral tables, variously modified ; hard and brittle, of a colour almost black, and a metallic lustre, but it soon tar- nishes ; it abounds in Cornwall, and is generally found in conjunc- tion with the ores of tin, in primitive formations. The only other native tungstate hitherto discovered, is that of lead, occuring at Zinnwald, in Bohemia, and which was formerly mistaken for a molybdate of lead. Moli/bdic Acid and Molybdates. 115. Molybdena, like tungsten, forms an acid with oxygen, and mineralizes other metals. Ochry Molybdena, which is found in Sweden and elsewhere, in the state of a yellow powder incrusting feldspar, or the native sulphuret of molybdena, appears to consist of the acid of this metal. Molybdate of lead occurs massive, disseminated, and foliated, or in lamellar hexaedral crystals, exbiting various tints of yellow. It was first found in Carinthia, and has been since met with in Hungary, Austria, Saxony, Mexico, and Massachusetts, frequently imbedded in quartz. Chromic Jicid and Chromates. 116. Chrome, or chromium, is another acidifiablc metal, though the chromic acid has not yet been found in a native state. Protoxide of chrome has been discovered in the department of the Rhone, in France, forming a green incrustation on other minerals, and it constitutes the colouring matter of the emerald. 117. Chromate of lead, or Siberian red lead ore, occurs in the gord mines of Beresof, in a kind of micaceous rock, mingled with In what state does tungsten occur in nature ? What properties does its compound with oxygen possess? Bv what names is the tungstate oflime known? Where is tungstate of iron met with ? What other salt of tungstic acid has been discovered ? What is the character of the compound of molybdena and oxygen? What is the chemical nature of ochry molybdena? In what form does molybdate of lead present itself? In what mineral is protoxide of chrome discovered ? z 2 270 MINERALOGY. particles of quartz and brown ironstone, forming- prismatic crystals of a deep orange colour, and sometimes accompanied by small green crystals, which are supposed to be chronite of lead, or a compound of the oxides of chrome and lead. Vauquelinite, a mineral accompanying the red lead ore of Siberia, is a chromate of lead and copper. Chromate of iron, containing also alumina and silica, has been found in France, in Maryland, and also in some places in Siberia, massive, or in octaedral crystals, of a black or bluish-black colour. Vanadic Add and Vanadiates. 118. Vanadium being one of those metals that combine with oxygen in different proportions, forming acids as well as oxides, it enters into union with the oxides of other metals. This metallic substance was discovered in 1830, by Sefstrom, a Swedish chemist, in a kind of iron ore found at Taberg, in Srno- land, but it has not been ascertained in what state the vanadium exists in that ore. Shortly after the metal had been observed in Sweden, Mr. J. W. F. Johnston, of Edinburgh, found the vana- diate of lead in a mineral from the mines of Wanlock Head, in which the vanadium constituted the principal electro-negative in- gredient, though chlorine, and the arsenic and phosphoric acids were likewise present.* There are at least two varieties of the Wanlock Head mineral ; the first resembling arseniate of lead, occurring in mammillary tufts on the surface of calamine, and sometimes passing into the chrystalline form; the other found amorphous, or in small round spots, of a black colour, like oxide of manganese, coating the calamine, or dispersed in cavities. Pro- fessor Del Rio had previously found the vanadic acid combined with oxide of lead, in brown lead ore, from Zumpan, in Mexico, Boracid Add and Borates. 119. Boratic add is found existing in nature in the Lipari Islands, and likewise in the hot springs of Sasso, in Tuscany, whence the term sassoline has been applied to it by some mineral- ogists. It occurs likewise in light crusts on substances in the neighbourhood of extinct volcanos. 120. Borax, called also tincal, is a native borate of soda, found in Thibet, Persia, Tuscany, and it is said also in Peru and China. Boradte, or borate of magnesia, occurs crystallized in cubes, and With which of the metals does chromic acid combine ? Where in the United States does chromate of iron occur ? By whom was vanadium first conclusively shown to be a distinct element? In what combinations was it found by Sefstrom ? Where have vanadiates of lead been discovered ? In what regions is native boracic acid found ? What chemical compound is native borax ? * JRejport of the British Association for 1832, p. 470. ARRAGONITE. 271 variously modified, of a light gray colour, opaque or translucent, and the crystals are found imbedded in gypsum near Kiel in Hoi- stein, and at Luneberg in Hanover. Datolite, a mineral of a pale greenish-white colour, massive or crystallized in cubes, sometimes modified, is found at Arendahl, in Norway ; whence also is ob- tained a globular fibrous variety called botryolite : both these minerals contain boracic acid combined with silica and lime. V Carbonates. 121. Carbonate of soda is found in some mineral waters, and most abundantly in the lake called Lagunilla, in Venezuela, from which the salt is procured as an article of commerce. A combi- nation of the carbonate and bicarbonate of soda is obtained in large quantities in the saline state, from the oasis of Gadamis, west of Fezzan, in Africa, where it is called trona. According to an analysis made by Mr. Richard Phillips, it consists of three parts of acid and two of soda, and hence he terms it a sesqui-carbonate of soda. 122. Strontianite is a rare mineral, of a greenish colour, found in radiated masses, and sometimes in acicular hexaedral crystals, generally imbedded in earthy barytes, and associated with galena ; it was first obtained from Strontian, N. B., and has since been discovered in Saxony, in Peru, and in Pennsylvania. Witherite, or carbonate of barytes, occurs in large masses in diverging fibres or crystallized in hexaedral prisms and pyramids ; forming some- times beautiful groups of double pyramidal crystals, the primitive form of which is an obtuse rhomboid. It has been found in Lan- cashire, and other northern counties of England, and also in Shropshire and in Wales. Baryto-calcite, is a compound of the carbonates of barytes and lime, which occurs in Cumberland, and was at first supposed to be a variety of carbonate of barytes, but it differs in crystallization, its primitive form being an oblique rhombic prism. 123. Carbonate of lime. This division of the carbonates com- prehends the multifarious varieties of calcareous spar, marble, chalk, and limestone, many of which are much more interesting in a geological than in a mineralogical point of view, and therefore will here require but a brief notice. 124. Arragonite is a mineral of a white colour with a pearly lustre, and sometimes with a reddish hue, which occurs in hexae- dral crystals, aggregated, grouped, or imbedded in gypsum, also arborescent, dendritic, or stalactitic, and likewise in acicular fibres, one variety of which has been called flos ferri, from its resemblance What is the composition and form of boracite ? Whence is it found ? Where is native carbonate of soda found? In what locality does the sesqui-carbonate occur? What is the appearance of carbonate of strontia? How does witherite crystallize ? What classes of familiar substances are among the carbonates of lime ? What is the external appearance of arragonite ? 272 MINERALOGY. to a delicate white flower. It has been found in Arragon, Bohemia, Styria, and France. Some specimens are found to contain three or four per cent, of carbonate of strontian. 125. Calcareous spar is a carbonate of lime in transparent crys- tals, the primitive form of which is a rhomb, passing into almost innumerable varieties ; its colour is various, but it generally ex- hibits light tints. Among the sub-varieties may be mentioned the dogtooth spar, with double hexaedral pyramids, joined at their base, and the short hexaedral prismatic crystals turned so that the lines of the pyramids correspond. This mineral, frequently called the Iceland spar, is peculiarly interesting, as having furnish- ed the means for the discovery of the double refraction of light. It is found in Iceland, in the Hartz mountains of Germany, and in Derbyshire, where it occurs in large crys- tals, of a topaz-yellow colour; and that kind called fontaine- bleau sandstone, contains a considerable admixture of quartz. 126. Stalactitic limestone, formed by deposition from the water of springs holding carbonate of lime in solution, is of various colours, as white, green, and brown, sometimes in the form of long tubes, in that of icicles, botryoidal masses, and a variety of other figures, one of which is represented in the margin. It is frequently found pendant from the roofs, or incrusting the walls of caverns, as in Derby- shire, the Island of Sky, St. Michael's Cave, i Gibraltar, in the famous Grotto of Antiparos in the Archipelago, and in the Mammoth Cave of Kentucky. Satin spar is a fibrous variety of carbonate of lime, of a snow-white, bluish, or green colour, which has derived its name from its peculiar pearly lustre, and which is found in Cumberland and in Swe- den. 127. Those limestones which admit of being finely polished, are generally termed marbles, of which there are a great many varieties. The white granular limestone, or marble of the primitive rocks, which is the most highly esteemed, is to be distinguished from the secondary limestone by the entire absence of organic re- What is the primitive crystalline form of calcareous spar? What is the form of dogtooth spar ? What optical phenomenon was originally discovered by means of ice- land spar? How is stalactite limestone produced ? Whence is the term satin spar derived ? CHALK. 273 mains, by its granularly foliated structure, and by its association with other primitive substances. The most valuable kind of statuary marble is the Parian, and that of Mount Pentelicus, near Athens, of which are formed some of the finest existing sculptures of antiquity. The marble of Carrara, in Italy, is also celebrated for its beauty, having been much employed by sculptors. It is of a milk-white hue, and less crystalline than the marble of Paros. 128. Many of the varieties of figured and coloured marbles are extremely beautiful, deriving their characteristic peculiarities from the admixture of various foreign bodies. There is a kind of marble found in Tirey, one of the Western Islands of Scotland, of a reddish colour, which contains sahlite, and probably titanium imbedded. Cipolin is a sort of statuary marble, with veins of mica. Brocatella is a breccia limestone, composed of fragments of a yellowish-red and purple colour, cemented by similar transparent calcareous spar. Verde Anticho and Verde di Corsica, are composed of compact limestone and calcareous spar, with serpentine and asbestus ; and of a similar nature is the va- riety called Mona marble. 129. Florentine marble is a grayish compact marble, witb ar- gillaceous earth, exhibiting designs of landscapes or ruins in yellowish-brown tints. Lumachella marble is a compact lime- stone, of a brownish-gray colour, in which shells are imbedded. Lucullite, or black marble, containing carbonaceous matter, is used for ornamental architecture and other purposes. Madre- porite, or prismatic lucullite, is so called from its resemblance in structure to madrepores. Swinestone, or fetid limestone, is a variety containing bitumen in various proportions, whence it de- rives a fetid odour. Much of it is found on the banks of the river Avon, near Bristol, England ; and there is a sectile variety met with iu Dalmatia, said to be about the consistence of soap. 130. Oolite, or roestone, is a variety of carbonate of lime, which derives its appellation from its structure and appearance, being composed of minute globular concretions, of a yellowish- brown or straw colour, much used in building, under the names of Portland stone and Bath stone. Pisolite, or peastone, some- what resembles the preceding, but consists of larger concretions, composed of concentric layers surrounding grains of sand, formed by deposition from hot springs, as at Carlsbad, in Bohemia, and at Tivoli, in Italy. Calcareous tufa is an earthy carbonate of lime, of a porous, spongy structure, forming casts or incrustations by deposition from water. Casts of medals have thus been obtained, by placing them in moulds to receive the spray impregnated with calcareous particles, and incrustations of a similar nature are How is primitive distinguished from secondary limestone ? What localities are celebrated for furnishing the finest marble ? What is the nature of verde antique ? What peculiarity does the Florentine marble present ? What occasions the odour of fetid limestone ? What is the appearance of Portland stone ? How is pisolite formed ? What imposition is practised at certain En- glish mineral springs by means of calcareous deposits ? 274 MINERALOGY. obtained from springs at Matlock and at Knaresborough, where they are sold as petrifactions. 131. Chalk and its varieties, rock milk and agaric mineral, are carbonates of lime ; and marl is chiefly composed of the same substance mixed with argillaceous earth. Carbonate of magnesia. Magnesite, which is a carbonate of magnesia, generally white and friable, or in fine acicular crystals, has thus been found in Piedmont, and in Moravia ; likewise at Hoboken, in New Jersey, in veins in a serpentine rock, accompa- nying the native hydrate of this earth ; and a variety has been obtained from the East Indies, which is white, massive, hard, of a conchoidal fracture, and translucent at the edges. The carbo- nate of magnesia more frequently occurs combined with that of lime, as in the dolomite, which is of a snow white colour, and granular texture, often containing realgar and pyrites. A variety of dolomite, found in Massachusetts, and elsewhere, exhibits a considerable degree of flexibility. Rhomb spar, or bitter spar, is a mineral of a yellowish or brown colour, which occurs, imbedded in chlorite schist, in the Tyrol, at Saltzburg, and in Sweden. Miemite, tharandite, and pearl spar, are varieties of magnesian limestone. 132. Among the carbonates of iron are sparry iron ore, of a grayish or yellowish-white colour, crystallized, fibrous, massive, and botryoidal ; which last variety has been termed spheero- siderite. This carbonate has been found in Cornwall, crystallized in hexagonal prisms, but its more usual form is the equiaxial rhomb. Carbonate of manganese, is found in globular or botryoidal forms of various shades of rose colour, with sulphuret of manganese and oxide of iron. Calamine, or carbonate of zinc, is found in tabulated crystals, generally tetraedral, and in acute rhombs, also compact, botryoidal, and in other forms, of various shades of colour, generally either green or brown. p. 133. Carbonate of lead, or sparry lead Jf ore, exhibits considerable variety of form. The compact carbonate, of a snow-white or cream colour and shining, is commonly associated with galena. It is also found semi-translucent, crystallized in double hexagonal pyramids on galena ; and it occurs in fibrous or canrcnlated crystals, sometimes coloured by green carbonate of copper. The earthy or pulverulent varieties are of a brown or cream co- lour. What is the nature of marl? Wilh what other carbonate is that of magnesia often associated ? What is the mineralogical name of elaetic marble ? What varieties of magnesia, limestone are enumerated ? What is the appearance of carbonate of iron ? of manganese ? of zinc ? In what forms does carbonate of lead occur ? What colour has it in powder ? ARSENIOUS ACID AND ARSENIATES. 275 134. Carbonate of copper exhibits some remarkable -varieties, some of which have been used as pigments under the name of mountain blue. Among these carbonates are the vel- vet copper ore, of a brilliant light blue colour, found only at Oravitza, in the Bannat, forming a velvet incrustation on malachite and brown ironstone. The green carbonates include fibrous mala- chite, occurring in acicular or fascicular and stellated crystals, and also foliated ; compact malachite is found massive, mammilated, with a zoned fracture, or crystallized in octaedrons or dodecaedrons, detached or imbedded in red cop- per ore. This ore, of a beautiful green velvet exterior, is found in Berks Co., Pennsylvania. Arsenious Acid and JLrseniates. 135. Arsenious acid. This acid in the native state called also arsenic bloom or octaedral oxide of arsenic, has been often con- founded with arseniate of lime : it occurs stalactitic, in delicate flat crystals or in silky filaments, of a white colour, incrusting other minerals. 136. Pharmacolite is a combination of arsenious acid and lime, found in capillary crystals, which look like little tufts of cotton. Arseniate of iron, or pharmacosiderite, is found chiefly in small cubic crystals in the tin mines of Cornwall, and in other parts of the world. Skorodite, which appears to be a cupreous arseniate of iron, is found in minute blue or greenish rhombic crystals, generally accompanying the preceding mineral. There are several varieties of arseniate of copper, as the octaedral arseniate of a sky- blue or emerald-green colour, in flat crystals; the tabulated arse- niate in flat hexaedral crystals, of an emerald colour; thetriedral arseniate, of a blackish or shining blue colour, crystallized in rhom- bic prisms, sometimes with diedral summits, and also flat, curved, aggregated, and variously modified; and the fibrous arseniate. 137. The arseniates of cobalt, or red cobalt ores, comprise the earthy and the radiated varieties, the former of which is a soft, friable mineral, of a rose colour, sometimes forming very small botryoidal concretions in the cavities of gray cobalt ; and the radiated variety consists of delicate acicular crystals ; sometimes of a stellular figure, fonnd upon other minerals in Cornwall, Scot- land, Saxony, Hungary, and Norway. Arseniate of lead occurs, in slender hexagonal crystals, upon quartz and steatite, in Saxony, Siberia, and especially in Corn- How does carbonate of copper crystallize ? What is meant by mala- chite ? In what situations does arsenious acid occur in nature ? What is the nature of pharmacolite ? What are some of the varieties of arseniate of copper ? What is the colour of the arseniate of cobalt ? Where is it obtained ? 276 MINERALFGY. wall. There is a reniform arseniate of lead in lamellar concretions, of a yellowish colour, found in Siberia. PhospJiates. 138. The phosphates of lime include some varieties. Apatite is a mineral of a grayish or green colour, crystallized in hexaedral prisms or tables, and variously modified. Some specimens are found of a violet colour; the green and blue varieties are called moroxite, and the pale yellow-green asparagus-stone, and this phosphate is sometimes found of a snow-white colour. Phos- phorite, formerly supposed to be of the same composition, with fluor spar, is a phosphate of lime, generally of a light reddish brown or whitish and yellowish colour, in distinct concretions, earthy or massive, found in Hungary and elsewhere. 139. Phosphate of lead, or pyromorphite, is found massive, crystallized in hexaedral prisms, dendritic, or earthy and friable, of a green and yellow colour; and also in hexagonal prisms and acicular crystals, of a deep orange or brown colour. Phosphate of yttria, or phosphyttrite, is a very scarce mineral, first found in granite, at Lindenas, in Norway; and afterwards, in similar small quantities, at Ytterby, in Sweden. 140. Phosphate of iron occurs in rhombic prisms, striated, acuminated, and variously modified, of a green colour ; it is alsa sometimes found of a blue colour, and likewise black. These varieties, except the last, have been found in Cornwall ; the earthy, blue iron ore, and wood, peat, and clay, impregnated with this mineral, have been met with in New Jersey.* Phosphate of manganese, or triplite, is a mineral of a shining black, or brownish-black colour, which rnelts before the blowpipe into a black enamel. Phosphate of copper has been found near Cologne, in Germany, of a green colour, in small rhomboidal crystals. Among the varieties of this phosphate may be specified the olive malachite, or octaedral phosphate, found at Lebethen, in Hungary; and the prismatic variety, called pseud* o mala- chite, from Rheinbreitenbach, where it is found with quartz, sometimes passing into calcedony. 141. Phosphate of alumina appears to form the basis of several minerals, the composition of which, however, has not been perfectly ascertained. Among these are the wavellite, formerly called hydrar- gillite, found in Devonshire, Ireland, Bavaria, Bohemia, Greenland, and Bra- Enumerate and describe the 1 native phosphates of lime ? What is the number of sides in prismatic phosphate of lead ? What variety of colour docs it exhibit ? What is the form of the crys- tals of phosphate of iron ? Wliat is the composition of wavellite ? * See Morton's Organic Remains, p. 16. CELESTINE. 277 zil, forming globular concretions, or fibrous and radiated groups ; the klaprothite, called also blue spar, or azurite ; the calaite, or real turquois, an opaque gem found principally in the province of Khorasan, in Persia, imbedded in a ferrugino-argillaceous rock; the kakoxene, a rare substance found in Bohemia, in the fissures of argillaceous ironstone, and exhibiting a crystalline fibrous structure, and a yellow colour ; and the childrenite, found at Tavistock, in Devonshire. 142. The phosphate of uranium includes the yellow uranite, or uran mica, found in France, in thin, quadrangular crystals ; and the green uranite, or chalcolite, in tetraedral tables, aggregated and detached, or elegantly grouped, which has been obtained chiefly from Cornwall and from Saxony. Nitrates. 143. Nitrate of potash, or native saltpetre, is found as an efflo- rescence, consisting of capillary crystals, incrusting chalk and limestone rock, at Polo di Molfetta, in Apulia in Italy, near Bur- gos in Spain, and elsewhere. In the vicinity of Evreux, in France, nitre is collected from the surface of the calcareous soil several times in the year; and it is obtained largely in the same manner, for the purposes of commerce, in the East Indies and other parts of the world. Nitrate of lime is often found combined with that of potash, and may sometimes be observed forming silky efflorescences on old walls ; it likewise occurs in some mineral waters. Sulphates. 144. The sulphates are a numerous class of minerals, including many of the soluble salts. Sulphate of soda, or glauber salt, is frequently found as an efflorescence, and sometimes in acicular crystals, near mineral springs and salt lakes. Thenardite is a hydrous sulphate of soda, found in crystalline crusts at the bot- tom of the briny waters at the Salines d'Espartines, in the neigh- bourhood of Madrid. Glauberite is a mineral composed of the anhydrous sulphates of soda and lime, found imbedded in salt and clay in the salt-mines of Villarubia and Aranjuez, in Spain. Reussite is a sulphate of soda, combined with sulphate of mag- nesia. 145. Celestine, or sulphate of strontian, a mineral of which there are several varieties, is found near Bristol, England, in France, the Where is calaite found ? In what localities has uranite been obtained ? What are the two nitrates which occur in a mineral form ? In what forms does the sulphate of soda occur ? What is the mineralogical name of sulphate of strontian ? 2 A 278 MINERALOGY. Tyrol, Spain, Sicily, and in Pennsylvania. It occurs of a sky- blue or gray colour, and sometimes of a white, yellowish-white, or brown ; massive and foliated, in tabulated crystals, in radiated fibres, or compact in hollow balls, with internal crystallizations. 146. Sulphate of barytes, or heavy spar, exhibits a considerable variety of crystallization, the primitive form being a right prism with rhombic bases. It forms large wax-like, yellow crystals, and is found in Cumberland, at Schemnitz in Hungary, Clausthal in the Hartz, Traversella in Piedmont, and elsewhere. The ra- diated or stellated variety of this sulphate includes the Bologna stone of Monte Paterno, used in the pre- paration of the Bolognian phos- phorus. (See marginal figure.) To these may be added the beauti- ful variety called chain spar, from the Hartz; the fibrous and the granu- lar varieties ; the prismatic barytes, generally of a brown-yellow colour ; the compact, called barytic or pon- derous marble; and the fetid or hepatic barytes, of a smoke colour, which occurs massive and nodular. 147. Sulphate of lime is found in abundance in France, Spain, and other parts of the south of Europe, exhibiting some varieties, among which may be specified selenite, or sparry gypsum, in hexagonal prisms, or variously modified, sometimes stained of a yellow colour by oxide of iron ; fibrous gypsum, opaque or trans- lucent, of a snow-white hue, with a silky lustre ; granular gyp- sum, or alabaster ; compact gypsum, white or variegated, and with red and white veins, which variety includes the stalagmitic gypsum of Guadaloupe. Anhydrous sulphate of lime, (likewise styled anhydrite, cube-spar, and muriacite,) is composed, as its name implies, of sulphuric acid and lime, without water ; and it is found crystalline, fibrous, granular, and compact, chiefly of a milk-white or bluish colour. Anhydrous sulphate of lime, con- taining silica, has been found in Italy, where it is called marmo bardiglio di bergamo, and by Count Bournon, bardiglione; and a variety occurs in the salt mines of Wieliczka, in Poland, which, from the peculiarity of its structure, is termed tripestone. Much of the gypsum used in the United States is imported from Nova Scotia. 148. Sulphate of magnesia, or Epsom salt, which is of common occurrence in mineral waters, as those of Epsom and Cheltenham, In what part of the United States may this mineral be met with ? What is the primitive form of sulphate of barytes ? What are some of the varieties in the form and other characters of this mineral? In what European countries is sulphate of lime found ? What is the chemical nature of alabaster? In what state is sulphate of magnesia often detected ? FLUORIDES. 279 is found in capillary or fibrous crystals at Calatayud in Arragon, and in the mines of Idria; and what is called stalactitic cobalt vitriol, from Herrengrund, in Hungary, is merely sulphate of magnesia, tinted red by oxide of cobalt. Polyhalite, formerly supposed to be anhydrous sulphate of lime, appears from the analysis of Stromeyer to consist of the sulphates of lime, magnesia and potash, muriate of soda, and oxide of iron, in a state of chemical combination, though the muriate and oxide occur in very small proportions. 149. Sulphate of zinc is a semi-transparent saline mineral, of a grayish 01 reddish-white colour, which seems to be produced from the decomposition of blende, the sulphuret of this metal. Sulphate of iron, copperas, is another product of spontaneous decomposition, being derived from martial pyrites, and appearing in the massive form, or in stalactitic fibres, yellow scales, or red concretions. Sulphate of cobalt is a soluble saline body, of a pale rose or flesh colour, and of an earthy texture, usually in the stalactitic form, found in the Hartz mines and elsewhere. Sulphate of copper is found in crystals of a fine blue or purple colour, but rarely of any considerable size or perfect form. Sulphate of lead occurs crystallized in cuneiform cctaedrons, variously modified or aggregated, imbedded in cellular quartz, tinged by oxide of iron. Translucent crystals, of a yellowish- gray colour, have been obtained from Parys Mountain, in the Isle of Anglesea. 150. Sulphate of alumina displays some variety of form and composition. Native alum is found crystallized, fibrous, and in other states, in various places; aluminite, or websterite, is a hydrated, subsulphate of alumine, mixed with sulphate of lime, resembling pure porcelain earth, found on the coast of Sussex, near Newhaven, and at Halle, in the territory of Magdebourg. Alumstone, likewise called aluminite, or alunite, occurring in a hill at Tolfa, in the Pope's dominions, contains potash as well as sulphuric acid and alumina ; and from this mineral is prepared Roman alum. Alumstone, in an efflorescent form, is met with in some parts of the U nited States. Fluorides. v!51. The fluor minerals, formerly regarded as fluates or combi- nations of an acid with oxidated bases, have been ascertained to consist of the electro-negative body fluorine, united with different metals. What is its crystalline form ? What is the composition of polyhalite ? How are the sulphates of zinc and iron supposed to be produced ? How does sulphate of lead crystallize ? 280 MINERALOGY. Fluor spar, erroneously nam- ed fluate of lime, is a fluoride of calcium, found in several parts of the world and exhi- biting various forms and co- lours. It occurs compact, fo- liated, crystallized, granular, and earthy : from Chamouny are obtained rose-coloured crystals ; from Siberia, a vari- ety called chlorophane, which emits a brilliant green light when heated ; and there is a figured variety called fortification fluor. (See marginal figure.) Yttrocerite, a violet-coloured mineral, found imbedded in quartz, at Ytterby, in Sweden, is a combination of the fluorides of cal- cium, yttrium, and cerium. Fluate. 152. Cryolite, is a mineral found in "West Greenland, which derives its name from its extreme fusibility, melting like ice: it appears from the analyses of Vauquelin and Berzelius, to be a com- pound of fluoric acid, alumina, and soda. It is of a colour ap- proaching to white, translucent, amorphous, having a foliated fracture, and softer than fluor spar. Chlorides. r 153. The chlorides are an important class of minerals, the na- ture of which, like that of the fluorides, was formerly greatly mis- apprehended. 154. Chloride of sodium, long known to chemists by the appel- lation of muriate of soda, is not onty found most abundantly in so- lution in sea-water, brine springs &c., but also occurs in vast masses in the state of rock-salt, at Cordova in Spain, Wieliczka in Poland, in Hungary, Siberia, Africa, arid the Andes of South America, and on the salt bluffs and prairies west of the Mississippi. It crystal- lizes in cubes ; and among its varieties are the fibrous, red, blue, and violet, and the stalactitical rock-salt. Chloride of ammonium, or rather muriate of ammonia, native sal ammoniac is found chiefly in the vicinity of volcanos. What is the true chemical nature of fluor spar ? What combination of substances exist in yttrocerite ? What is the peculiarity of cryolite ? What is its chemical nature ? What name was formerly given by chemists to common salt ? What is now its chemical designation ? How extensively does this mineral prevail ? Where is chloride of ammonium found ? COAL. 281 155. Among the chlorides of lead are the cotunnite, from Mount Vesuvius ; the basic muriate of lead, found in the mines of Men- dip ; and the murio-carbonate of lead, a rare mineral found in Derbyshire, crystallized in square prisms terminated by pyramids, of a yellow colour. Chloride of copper, or atacamite, is a mineral which forms beau- tiful groups of green crystals, found in Chili and Peru. 156. Chloride of silver, called corneous silver, or horn silver, from its appearance, is found massive and crystallized ; in colour and form resembling gum arabic ; or of a pale-yellowish green or brown, botryoidal, lamellated, earthy, or crystallized in minute cubes and octaedrons. Chloride of mercury, which has the same homey appearance, crystallizes in small square prisms, terminated by flat pyramids, and otherwise modified. It is so soft as to be sectile ; and it be- comes volatilized before the blowpipe. Organo -Chemical Substances. Salts. 157. Mellate of alumina, called mellite, or honeystone, from its appearance, is found in small amber-coloured crystals, in beds of brown coal, in Thuringia. Oxalate of iron, also called humboldtite, was formerly considered as resinous iron ore. Resins. 158. Amber exhibits numerous varieties, arising from various causes, and some specimens are extremely curious, from the bodies imbedded in them. It occurs in rounded pieces, rough on the outside, and within of a yellowish, white, or reddish colour; and is found on the coast of Norfolk in England, Prussia, Mozam- bique in Africa, and other parts of the world. Some specimens were obtained in excavating the Chesapeake and Delaware canal. Fossil copal, or Highgate resin, a substance somewhat resem- bling amber, found in making excavations for the road at Highgate. Retinite, or retinasphalt, a mineral from Bovey, in Devonshire, of a yellow and reddish-brown colour, which burns with a fragrant odour. Bitumens. Varieties Naphtha, petroleum, elaterite or elastic bitumen, and indurated petroleum. What is the common designation of chloride of silver? What is the difference in the crystalline forms between the chloride of mercury and that of silver ? Where is mellate of alumina found ? What interesting peculiarity is exhibited by amber? What classification of substances arises from their modes of aggregation ? 2 A2 282 MINERALOGY. Coal. 160. This substance presents some varieties, more interesting to the geologist than to the mineralogist ; and of these some no- tices may be found in another part of this volume.* * See Oryctology. Works in the Department of Mineralogy. Cleaveland's Mineralogy. 2 vols. 8vo. Phillips's Mineralogy. Ure's Dictionary of Chemistry, under the names of the several minerals. Hauy Traite de Mineralogie, 4 vols. 8vo., and an Atlas, con- taining 120 plates of mineral forms, tables of characters and angular measures. Though the system of Hauy is now super- seded by more modern arrangements, his work is often found of important service in consequence of these numerous valuable il- lustrations, which aid the student in determining a mineral by its external characters. Moh's Treatise on Mineralogy, translated by Haidinger. 3 vols. 12mo. Del Rio's Elementos de Oryctognosia. 1 vol. 8vo. Philad. 1833. Allan's Manual of Mineralogy. 1 vol. 8vo. Edinburgh. 1834. CRYSTALLOGRAPHY. 1. SOLID bodies appear under a vast variety of forms, some depending- on organization, and others on molecular attraction; the latter of which only require to be considered at present. These forms or modes of aggregation are either regular or irregu- lar; consisting in the one case of geometrical solids, variously modified; and in the other, of amorphous solids, or those which display no symmetrical proportions. 2. Certain figures, arising from molecular attraction, are termed crystals, constituting polyedral solids, terminated by surfaces, regular, connected, and often shining with a lustre equal to that of a polished gem. Few objects of this kind are more beautiful than frozen water, as it occurs in a state of large snow-flakes when examined by a microscope ; or as it may be observed in the hoar-frost, incrusting with most delicate network our trees and hedges, or formed by the congelation of moisture on the panes of windows in a cold winter's morning.* 3. 'Those bodies which are capable of crystallization have been observed to affect peculiar forms : thus rock-crystal frequently occurs beautifully transparent in hexaedral prisms, terminated by six-sided pyramids ; the Derbyshire fluor spar crystallizes in cubes, as likewise does common salt ; alum, or sulphate of alumine, forms octaedral crystals; and sulphate of magnesia tetraedral prisms. These forms, however, are liable to modification and diversity from different causes, as will be subsequently explained. /Fluor spar and galena sometimes exhibit octaedral and sometimes cubic crystals ; and carbonate of lime appears in such a variety of forms that it is difficult to decide which is of the most frequent occur- rence. *'Comte de Bournon, in his elaborate treatise on this mineral, has enumerated fifty-six modifications ; which, differently combined, furnished him with above six hundred varieties of form."f 4. The figures of crystals may be conveniently observed by making solutions of several salts in water, suffering small por- tions to crystallize, by evaporation, and then examining them through a microscope. \ What is meant by the terra crystal ? How is the process of crystallization best illustrated ? What important leading fact constitutes the basis of this science ? What deviations from uniformity are observed in crystals of the same substance ? How may the figures of crystals be advantageously studied ? * See Treatise on Meteorology. t Mrs. Lowry's Conversations on Mineralogy, 2d edit., vol. ii. p. 26. 283 284 CRYSTALLOGRAPHY. Mum. Common Salt. Epsom Salf. Take a dram of alum, and similar quantities of common or table salt, epsom salt, glauber salt, nitre, 01 any other soluble saline substances ; and place them, separately, in clean wine-glasses, or gallipots, then pour on each parcel rather more than enough water to cover it; and stir- ring the liquors frequently, after they have stood half an hour, let a drop of each fall on a strip of clean plate-glass, and place it in the sun or on the chimney-piece, protected from the dust, so that the water may be driven off; and more or less regular crystals will be formed, having a pleasing appearance when viewed through a microscope. The mar- ginal figures will afford some idea of the man- ner in which the crystals of the different salts above mentioned are grouped and constituted. 5. The modifications of form which are ob- served in crystallized bodies are sometimes owing to the sudden and consequently irregu- lar aggregation of the crystalline particles ; and sometimes the presence of foreign bodies may accelerate, interrupt, or very materially interfere with the process of crystallization. Hence the angles or edges of crystals may be truncated or rounded ; and cylinders, spheri- cal, lenticular, or agglomerated masses may be produced, bearing but a faint resemblance to the proper form of the salt. 6. In order to obtain regular, large and well- shaped crystals of any salt, a saturated so- lution should be made in distilled water, and set by in a moderately warm situation, where it may remain undisturbed, so that the fluid may evaporate slowly; and a gradual deposition of the saline particles will then take place, yielding symmetrical crystals of a larger size than can be produced by any other management. 7. The interesting appearance of certain crystals and their relative permanence of form, amidst a seeming variety, drew forth some striking observa- tions from Dr. Freind, in his lectures on chemistry at Oxford, in the early part of the last century. 8. " The beauty and variety of the figures of crystals is so To what are modifications of crystalline forms supposed to be due ? How are the perfect crystals of a salt to be obtained ? Glauber Salt. ISOMORPHISM. 285 admirable, that there is scarcely any thing in nature which can entertain the eye more agreeably. These figures are sometimes eeen by the naked eye, but by the help of microscopes are dis- cerned much better. In common salt we plainly discover quadri- lateral pyramids, with square bases ; in sugar, the same pyramids, Nitre. with oblong and rectangular bases. The crystals of vitriols very much resemble ici- cles, united one to another with great va- riety; among which lie some polygons, as may be discovered by the naked eye. Sal ammoniac very elegantly imitates the branches of a tree ; and salt of hartshorn (carbonate of ammonia) looks like a qui- ver of arrows." Glauber's sal mirabilis, which is made of common salt and vi- triol, (sulphate of soda,) exhibits the figure of both salts. Nitre appears in certain prismatical columns, not much un- like bundles of sticks; among which there are interspersed some rhomboids* and some pentagons, which seem to come very near those of common salt. Hence Lemery has justly remarked, that nitre could not be purified by any art or contrivance whatever; but something of a sal gem, 01 fossil salt, would stick to it. But salt of tin outdoes all for beauty, in which are lines like little needles, which spread themselves every where from a point, as from a centre, so as to represent a star, much like what we see in the regulus of Mars, (metallic iron.)"f 9. Dr. Freind proceeds to remark, that it is a circumstance " very peculiar in these salts, that let them be never so divided, and re- duced into minute particles, yet when they are formed into crys- tals, they each of them reassume their proper shape ; so that one might as easily divest and deprive them of their saltness as of their figure." The intimate relation between crystalline form and chemical composition, which attracted the attention of this inge- nious writer, has been extensively investigated by more recent inquirers. 10. Among the facts w T hich have been disclosed in consequence of their 'researches, one of the most singular and important is, that bodies, both simple and compound, which are capable of crystal- lization, appear to form groups characterized by similarity of structure ; so that one group may include several substances, all crystallizing in similar square prisms, another group consists of What observatious on crystalline forms were made by Dr. Freind ? What did Lemery remark in respect to nitre ? What important facts in regard to similarity of structure have been dis- closed by modern mineralogists ? * Nitre sometimes consists partly of nitrate of soda, which forms rhom- boidal crystals ; but nitrate of potash, when quite pure, crystallizes in hexaedral prisms, generally with diedral summits. t Chymical Lectures, by John Freind, M.D., 1712, pp. 144146. 286 CRYSTALLOGRAPHY. bodies forming similar octaedral crystals, and various others, the members of which respectively are distinguished by peculiar figures. As an example of such a group of minerals may be men- tioned calc spar, (Iceland crystal,) bitter spar, carbonate of mag- nesia and iron, carbonate of iron, manganese spar, zinc spar, and magnesia spar, all crystallizing in rhomboedrons. The discovery of this disposition among mineral bodies differently constituted to assume a common form, led to the assumption of the doctrine of isomorphism, already alluded to in the Treatise on Chemistry.* The law of isomorphism, as announced by Mitscherlich, in its ut- most generality is as follows : "'The same number of atoms com- bined in the same way produces the same crystalline form ; and the same crystalline form is independent of the chemical nature of the atoms, and is determined only by their number and relative position."! 11. A few observations may be added to explain in some de- gree the general principle on which depends the association of isomorphic substances. An examination of the group of rhom- boedral minerals mentioned above, will demonstrate amidst diver- sity of composition a similarity of atomic constitution. All those bodies of which crystallized carbonate of lime, or calc spar, may be regarded as the isomorphic type, appear to correspond in the number of their atoms with that body : thus, Calc spar consists of 1 carb. acid -f- 1 lime Bitter spar .... 1 carb. acid-f- 1 lime-f- 1 carb. acid + 1 magnesia. Carbonate of magnesia and iron consists of 1 carb. acid -\- I mag- nesia -j- 1 carb. acid-|- 1 oxide of iron. Carbonate of iron 1 carb. acid + 1 oxide of iron. Manganese spar 1 carb. acid + 1 oxide of manganese. Zinc spar 1 carb. acid -f- 1 oxide of zinc. Magnesia spar 1 carb. acid-f- 1 mag- nesia. 12. In all the simple carbonates of the preceding- group, one atom of carbonic acid is combined with one atom of a metallic pro- toxide ; and in the compound carbonates the atomic quantities are What examples can be given of minerals thus resembling each other in form though differing in constitution? What law of isomorphism is applicable to these cases? Illustrate this in the case of mineral carbonates. * See p. 123, note. t Rep. of Brit. Assoc. for 1832, p. 422. For a list of isomorphic bodies by Prof. Miller, see the same volume. ISOMORPHISM, &C. 287 are doubled. The same correspondence of atomic constitution seems to prevail in groups of more complicated chemical combi- nation^ : thus tremolite and anthophyllite are double silicates, the composition of which is as follows : Tremolite consists of 1 lime+ 1 silica + 3 magnesia + 2 silica. Anthophyllite . . 1 oxide of iron -f- 1 silica -f- 3 magnesia -j- 2 silica. 13. Hence it appears that the only difference between these Dodies consists in the former containing one atom of lime, (pro- toxide of calcimn,) and the latter one atom of protoxide of iron ; and they both crystallize in oblique prisms. In numerous other cases it has been found, that one oxide or acid, having the same atomic constitution with another oxide or acid, may replace it, or be substituted for it in the composition of minerals, giving rise to similar crystalline forms ; and thus groups are produced, each composed of two or more bodies corresponding in the numbers of their atoms, and in crystalline form. 14. There is an inferior degree of analogy of form observable among minerals, which probably arises, as in the cases already noticed, from the atomic constitution of bodies. Certain crystal- line compounds are found to differ among themselves merely in the angular measurements of their crystals. Thus sulphate of ba- rytes, sulphate of lead, carbonate of lead, and some others, form right rhombic prisms ; but the obtuse angles of the rhombic prism of sulphate of barytes measure 101 42'; those of sulphate of lead 103 42'; and those of carbonate of lead 117 18'.* Hence groups of bodies thus related are said to be ple&iomorphous ;-j- and the term fwmoiomorpkous^ 1ms been adopted to distinguish groups of crystalline substances differing more widely in their angles. 15. It has also been remarked, that while differently constituted compounds may agree in crystalline form, there are bodies, both simple and compound, which are capable of existing under two forms, which are incompatible or not derivable from one common How is the composition of compound carbonates seen to be analogous to that of simple ones ? How is tremolite shown to be isomorphic with anthophyllite ? What substitution of an ingredient is often found consistent with the preservation of a crystalline form ? In what circumstances are crystals, otherwise similar, found to vary from each other ? What is the measure of the obtuse angles of sulphate of barytes ? ol lead ? What of the carbonate of lead ? What term expresses the relation of crystals of which the angles are nearly the same ? What term applies to those which having forms generally alike differ greatly in the angles ? * Report of the British Association for 1832, p. 428. t From the Greek IIA^fftoj, nearly alike, and Mop^ybrm. t From the Greek "G^ony, similar, and M0p>>. 288 CRYSTALLOGRAPHY. | form. Sulphur is found crystallized in octaedrons with rhombic bases, and also in rhombic prisms. Pure carbon occurs in nature in two states, constituting the diamond and graphite; the former exhibiting regular octaedral crystals, and the latter crystallizing in hexaedral plates, striated parallel to some of their sides. Sulphur and carbon thus display a duplicity of form, a property in these and other bodies denoted by the term dimorphism.* 16. The phenomena of plesiomorphism, homoiomorphism, and dimorphism, which have all an obvious relation to isomorphism, indicate the necessity of further researches to elucidate the nature and causes of these appearances, which may probably lead to very curious and interesting discoveries. 17. The modifications and seeming anomalies of form which often occur in crystallized bodies take place under certain laws ; the deviation from the usual figure of the crystal depending on addition or subtraction of parts necessary to make up the regular solid, or primary form of a mineral, in any given case. -That the varieties of form in crystals of the same mineral may be referred to truncations of an invariable primary nucleus, was an opinion that appears to have been started by the French mineralogist, Rome de Lisle ; the idea also occured to Gahn, professor of mineralogy at Upsal, who having broken a piece of the dogtooth calcareous spar, observed that it was throughout composed of rhomboidal crystals ; and hence Professor Bergmann was led to conjecture that in all crystallized bodies there must exist a primary nucleus. 18. The inquiry was then taken up by the Abbe Haiiy, who is said to have had his attention drawn to it by an accident in itself somewhat awkward and perplexing. A person of fortune who had collected a cabinet of minerals as expensive curiosities, was showing them to M. Haiiy ; and, handing to him one very beau- tiful crystalline specimen that he might inspect it more readily, the stone slipped from the hand of the visiter, and falling on a marble pavement, was split in several pieces, which the owner regarding as worthless, while courteously accepting the apologies of the chagrined philosopher, ordered a servant to take up and throw away. M. Haiiy struck with the brilliance of the smooth surfaces of the fractured parts begged to be allowed to inspect them, and took them home to examine the structure of the mineral more at leisure. He found that it was susceptible of cleavage only in particular directions, and to a certain extent ; and having made corresponding observations on other crystallized substances, he was at length enabled to reduce to a regular system the laws To what is the term dimorphism applied ? By whom was the idea of primitive crystalline forms first advanced ? What circumstance is said to have led Haiiy to the investigation of primitive nuclei? On what plan did he proceed to form his system of mineralogy ? * From the Greek At j, twice, (in comp. a omitted,) and Mop0^. PRIMITIVE FORMS OF CRYSTALS. 289 of crystallization, with reference to the manner in which crystals are deduced in their several varieties from a primitive nucleus. 19. The relations between the different modifications of form in a mineral may be exemplified by taking a crystal of the fluor spar in one of the simplest of its natural forms, the cube, exhibited in No. 1. ^6 margin. Now it will be found on trial that the solid angles, A, B, C, D, &c., may all be removed by a knife with proper pressure, and thus the eight angles may be replaced by brilliant, flat, triangular surfaces, as in the next marginal figure, No. 2. The solid will then consist of fourteen sides instead of No. 2. six ; and each of the triangular sides may be enlarged at the expense of the square sides, by continuing the cleavage of increasing triangular planes, so as to form* the succeeding figure, No. 3. 20. At length, pursuing the separation of the crystal strata in the same direction, will be produced the re- maining figures, Nos. 4 and 5, in the last of which no part of the original cube remains, every angle having been cut away so as to form eight new faces, consti- tuting an octaedron, which is the primary form of the fluor spar. 21. A crystal of common salt, exhibiting the same No. 4. cubic form with the fluor spar, differs from it in structure, for its angles cannot be separated so as to leave a smooth surface ; and the crystal will admit of cleavage or sub- division only in layers parallel to either or all its sides ; No. 5. so that a large cube can be separated into a number of small ones, but not reduced by cleavage to any other form ; hence the cube is the primitive form or nucleus of the crystal of common or sea salt. In the same manner, pon- derous spar, or sulphate of barytes, can be divided with regu- larity only so as to form right rhombic prisms ; and selenite, sul- phate of lime, into right prisms : these therefore are the nuclei, or primitive forms of their respective crystals. 22. As the primitive nuclei of crystals may be developed by dissection, so it may be ingeniously shown how the varieties of crystals may be derived from the superposition of lamina on parallel surfaces, diminishing regularly in extent, so as at length to form the summit of a solid angle, or- the edge of a line joining two angles. It is in this manner that Hatiy, attributing to every crystallizable substance a primitive or simple form, ascer- tained by division as before stated, or else inferred from a compari- In what manner may the cube of fluor spar be first varied by cleavage ? To what form will it be ultimately brought ? How does the crystal of chloride of sodium differ from that of fluoride of calcium in regard to the cleavage of its angles ? To what primitive form is the crystal of ponderous spar capable of being reduced ? To whom is the doctrine of increments and decrements in crys- tals to be ascribed ? 2B 290 CRYSTALLOGRAPHY. son with others already known, proceeds to derive, from his doc- trine of increments and decrements, the various secondary forms that may be observed in different specimens of any given mineral. 23. According to the system of Hauy, all crystals are derived from five or six primitive forms. These are, (1.) the parallelopiped, including the cube, rhomboid, and all their varieties; (2.) the tetraedron; (3.) the octaedron ; (4.) the hexaedral prism; (5.) the rhomboidal dodecaedron ; to which may be added, (6.) the dodecaedron, with isosceles triangular faces. 24. All solids having six sides, whose respective bounding, lines taken in pairs are parallel with each other, and the opposite sides also equal and parallel, forming so many parallelograms, are termed parallelepipeds. Such an arrangement of surfaces must Obviously admit of some variety ; and thus it maybe perceived that the parallelopiped will include the cube, the square prism, the rhomboid, the right rhombic prism, and the oblique rhombic prism. /] 25. The cube, as appears in the margin, has six square sides, all equal, like common dice ; it's proportions being invariable. ' 2G. When a body is terminated by four equal oblong parallelograms laterally, and two square parallelograms at the ends, it is called a square prism. 27. The rhomboid has its opposite sides equal and parallel, but none of them are square, each having two obtuse and two acute angles, instead of four right an- gles, like the cube. 28. There are many varieties of rhomboids characterized by the relative diversities of their corresponding angles ; some rhomboids differing so little from the perfect cube that their real nature can only be ascertained by the measure- ment of their angles, others bearing but a very distant resemblance to it, as in the marginal figure, representing a very oblique rhomboid. 29. The right rhombic prism bears the same relation to the square prism that the rhomboid does to the cube. In the square prism the angles are all equal, and are right angles ; but in the right rhombic prism the sides or lateral planes meet alternately at angles greater or less than 90 degrees ; but the terminal planes, or those at the extremities of the prism, form by their junction right angles. To how many and what simple forms did Hairy reduce all crystals ? What is a parallelopiped ? How many varieties does it admit? How does the rhomboid differ from the cube? What is an oblique rhomboid? How is the right rhombic prism formed ? PRIMITIVE FORMS OF CRYSTALS. 291 30. The oblique rhombic prism differs from the preceding figure in the position of its terminal planes, which do not form right angles with the lateral planes, but are placed obliquely, so that the terminal and lateral planes meet at obtuse and acute angles alternately. 31. The tetraedron is the simplest of all regular figures A having plane surfaces. It is a solid, included within four triangular planes, equal and similar, each of the three sides being of the same dimensions. Some notice has been already taken of the octaedron, as the figure produced by the truncation of the solid angles of a cube. There are varieties, however, of this figure, arising from those of the eight planes, by which it is terminated. ,4x 32. The regular octaedron has all its planes equal and ^-\-~^\ similar triangles, each of their three sides being of the \A / same length. All lines drawn through its centre from ^ / ^ either angle to that opposite to it will be of equal length, or in other words it has three equal axes. This, however, is not the case with all octaedrons, some having one axis longer and some shorter than the other two. ^r. 33. The obtuse octaedron differs from the former in y^ ^-xhaving tne ^ ne which forms the base of its triangular ^\7*r ~~/ sides longer than those which meet at the apex, so ^^\/ that what may be termed its principal axis is shorter than its other axes. 34. The acute octaedron will be perceived at once to be n\ exactly the reverse of the foregoing, its base line being // \ shorter than those which form the apex, and its principal, Vf/ axis longer than the others. These forms will obviously ad- W mil of\ several modifications, the nature of which may be * comprehended without difficulty from what has been already stated. O35. The hexaedral prism derives its name from the number of its sides, which are similar parallelograms, not square, but oblong. They are six in number, and are called lateral planes, and as they meet the terminal planes, the latter are hexaedral and hexagonal ; that is, they have six edges and six angles. The terminal planes are parallel with each other. - 36. The rhomboidal dodecaedron, as its name implies, \**\ has twelve sides. These are all of similar form, each >plane being a rhomb, of which the four bounding lines are of the same length, and the opposite lines are parallel, forming two acute and two obtuse angles in each plane. How is the oblique rhombic prism formed? What peculiar character does the tetraedron possess compared with other figures ? What is a regular octaedron ? an obtuse octaedron ? How does the acule differ from the two other forms of octaedron? How many sorts of planes belong to prisms? What are the plane figures constituting the bases of hexaedral prisms? What is the plane figure of each side in the rhomboidal dodecaedron ? 292 CRYSTALLOGRAPHY. This figure is susceptible of numerous modifications, by tbe trunca- tion of edges or angles. 37. The dodecaedron with isosceles triangular faces is a figure having twelve equal triangular sides, differing from the octaedron in the number of its sides, and like that figure, admitting of modifications, according to the length of its principal axis. 38. The connexion of one form with another, or the transition from one to another, has been exemplified in the deduc- tion of the octaedron from the cubic crystal of fluor spar. (See p. 289.) The following figures will serve in like manner to show what modifications are produced by the truncation of the angles and edges of an octaedron : A B C 39. In fig. A, the angles only of the octaedron are truncated, in fig. B, the edges only, and in fig. C, both the angles and the edges. If we suppose the division of an octaedral crystal to be continued in the direction of the planes formed by the truncation of the edges, fig. B, in which the triangular planes of the truncated octaedron are separated from each other by narrow hexangular planes, a modification will be produced, exhibiting an increase of the hexangular planes, and reduction of the triangular ones, each however retaining its characteristic shape. 40. By pursuing the division in the same direction, the original planes may be entirely removed, the triangular faces disappearing, and the hexangular ones being changed into rhomboedral surfaces. Such a series of modifications may be observed in the fluor spar, and more commonly in the red oxide of copper, serving to show how the rhomboedral dodecaedron may result from the replace- ment of the edges of the octaedron. But in neither of these minerals can the rhomboedral dodecaedron be obtained by cleavage from the truncated octaedron ; for the laminae of the crystal of fluor, or red oxide of copper, admit of separation only in directions parallel with the planes of the octaedron, that being the primitive form or nucleus of the crystals of the mineral in question. 41. In this transition from one form to another in the construction of crystals, it seems as if nature in the generation of each crystal assumed a central nucleus* regular and constant in each species IP what three modes may the simple octaedron be varied by truncation ? To what form would continued cleavage along the edges only eventu- ally lead ? In what minerals do we find a form similar to what this process would produce ? LAW OF DECREMENTS. 293 respectively, and on the several faces of that nucleus applied suc- cessive laminae, all parallel and similar to each other, but diminish- ing regularly in extent, so as at length to terminate in a point forming the summit of a solid angle, or in a line forming the edge of the new crystal. 42. Thus from a cubic nucleus, the formation of a rhomboidal dodecaedron may be supposed to take place, by the addition of successive laminae on each face of the cube, which having a height denoted by 1, decrease gradually on their borders by a quantity also denoted by 1. So likewise a solid of twenty-four faces may be conceived to be formed from a cube by the application of laminae, the thickness of which is denoted by 1, and the successive lateral decrements by 2, by 3, or any higher number, according as the pyramid is more or less elevated or depressed. 43. An octaedron may in like manner be formed from a cubic nucleus by the successive application of laminae having angular decrements ; and by irregular, intermediate, or combined decre- ments, a vast variety of secondary forms may be produced from a very limited number of primitive nuclei. Hence in general, when the form of the nucleus of a mineral has been ascertained, nothing, is more easy than to determine in what manner laminae must be applied, and the law according to which they ought to decrease, in order to produce any given form of a crystal, the angles of which have been previously measured. 44. " But however ingenious this method of accounting for the diversity of crystals of the same substance may appear, and im- portant as were the discoveries of the learned author, it must be admitted that it can only be regarded as an hypothesis which may assist us in our researches. Indeed it is not probable that nature should commence by the formation of the primitive crystal, in order to apply to it decremental laminae. The bare inspection of crystals, which are often exceedingly small, and yet highly complicated, appears, on the contrary, to announce that all the forms have been produced by a single effort, (prodnites d'un seuljet ,) while on the other hand, it may be observed that the large crystals are only regular assemblages of very small ones, often similar to the large crystals which they form, and sometimes different from them."* 45. " These observations prove clearly, that, in general, crystalli- zation does not take place in nature according to the supposition adopted in the theory which has been given, but that the different crystals result rather from the sudden arrangement of the regular molecules among themselves, in the act of spontaneous solidifica- tion. For in studying the manner in which certain particles infi- How may a rhomboidal dodecaedron be conceived to result from a cubic nucleus ? How may the solid of twenty-four faces be derived from the same origi- nal form ? To what objection is the theory of Haiiy shown to be liable? * Beudant Traite Element, de Physique, p. 85. 2u2 294 * CRYSTALLOGRAPHY. nitely [indefinitely] minute, of a determinate form, may combine together, according to the number and the position of their faces, we may be led to conclude that the different polyedral figures to which they give rise depend on the number in which they are at- tracted together at the moment of crystallization. Thus, for example, it may be comprehended that cubic particles can only form complete cubes in those cases in which these molecules unite together in cubic numbers, as 8, 27, 64, 125, &c. 46. With a little attention, we perceive, likewise, that regular octaedrons can only be formed when cubic molecules combine in one of the numbers of the series 7, 25, 63, 129, &c. Further, dodecaedrons with rhombic planes will be produced when the molecules are attracted together, in one of the numbers of the series 33, 185, 555, &c."* 47. These speculations might be pursued further, and it might be shown how other forms might be derived from cubic particles ; but some figures would require for their production very extensive and complicated series of numbers of molecules ; and hence this theory is objectionable, as wanting that simplicity usually observable in the laws of nature. There is more probability in the hypothesis ingeniously proposed by Dr. Wollaston, who considered the primitive particles as spheres, which, by mutual attraction, assume that arrangement which brings them as near as possible to each other. 48. When a number of similar balls are pressed together in the same plane, they form an equilateral triangle ; and if, when thus arranged, they were cemented together, and the mass afterwards broken asunder, the lines in which separation would most readily take place, would form with each other angles of 60 degrees. A single ball placed any where upon such a stratum would touch three of the lower balls, and planes parallel to the sides of the figure thus formed would include a regular tetraedron. A square of four balls, with a single ball on the centre of each surface would constitute an octaedron ; and on applying two other balls at op- posite sides of the octaedron, the group would represent an acute rhomboid. The construction of the numerous varieties of figures which occur among crystals might be readily explained, by ad- mitting the existence of oblate and oblong spheroidal molecules, as well as those of a globular figure. f 49. Crystals may not only differ one from another, as a rhombic prism from an octaedron or a dodecaedron, but one rhombic prism may differ from another; for, since the rhomb is characterized by having one of its adjacent angles smaller than a right angle and To what circumstance may \ve attribute the different forms of crystals supposing the ultimate particles all alike ? What hypothesis did Dr. Wollaston propose for the solution of the ques- tion respecting crystalline forms ? * Beudant Traite Element, de Physique, p. 86. t Brande's Manual of Chemistry, 3d ed., vol. i. p. 16. GONIOMETER. 295 the other larger, it must be manifest that the one may consist of almost any number of degrees less than 90, and the other of any number below 180, which sum, however, must be the amount of the two angles taken together. For the four angles of the crystal collectively, will be equal to four right angles, i. e., 90 X 4 = 360, or the number of degrees of a circle by which angles are measured. 50. Thus the primitive form of carbonate of lime, calcareous spar, is a rhomboid whose faces are inclined at angles of 105 5', and 74 5', both together making 180. Tourmaline has for its primitive crystal an obtuse rhomboid, the angle of which is 113 10', and in like manner other minerals have their peculiar and constant forms, the precise nature of which can alone, in many cases, be ascertained by measuring the angles of the crystal.* 51. Instruments for this purpose, called goniometers, are chiefly of two kinds, the common and the reflective goniometer. The first and simplest of these instruments consists of a protractor, or semi- circular scale, graduated from to 180, with a small pair of com- passes applied to it, destined to receive the crystal whose angles are to be measured. 52. One arm of the com- passes, F G, in the annexed figure, forms the diameter of the semicircular arc, and the other arm, A B, the radius of that arc, and this last being moveable on the pivot /, the two arms may be made to form any given angle with each other. The transverse arm is grooved or slit from n to r, except at &, where there is a little-, cross piece to strengthen it. By means of this slit, and the two pins ra and n, this arm may be slid across the diameter of the arc, passing How may crystals having a general resemblance be found to differ ? What is the primitive form of carbonate of lime? of the tourmaline? By what instruments are the angles of crystals measured ? What is the ordinary form of the goniometer ? Who first discovered the constancy of angles in crystals? (See note.) Describe the common goniometer? * Rome de PIsle first called the attention of mineralogists to the remark- able fact, " that notwithstanding the irregular and changeable enlarge- ments of certain faces, and the indistinct formation of the edges between these faces, the angle at which they meet always remains constant, This peculiarity affords one of the most distinctive characters which minerals possess ; one by which the mineralogist is frequently led immediately to the determination of a species, and which, therefore, it is evidently of ex- treme importance he should ascertain with precision." Manual of Mine- ralogy, comprehending the more Recent Discoveries in the Mineral Kingdom. By Robert Allan, F.R.S.E., M.G.S. 1834. p. 16. 296 CRYSTALLOGRAPHY. through the points zero and 180. The pin m passes through a brass knob behind the arm F G, which is attached to the semi- circle at N, and by the bar O. The arm A B has a groove from C to B, by means of which, when necessary, that arm may be shortened, by sliding it upwards. 53. In order to use this instrument, it is merely requisite to place the crystal to .be measured between the compasses,.the arms of which being brought in exact contact with the planes forming the angle required, and the arm A B applied to the protractor, the value of the angle may be read off at the fiducial edge z s. 54. Though this instrument is serviceable to ascertain to a given extent the angles of crystals, it is far inferior in accuracy to the reflective goniometer, invented by Dr. Wollaston, the use of which, however, requires more skill and attention in the experimenter. For an account of the latter, and of the method of employing it, we must refer the reader to the works of those who have treated the subject of crystallometry more fully than is consistent with the limits to which we are confined.* 55. Among the latest and most important improvements in crys- tallographical mineralogy, is the introduction of crystallometrical systems : as the tesseral ; the tetragonal, or square pyramid of Mohs ; the rhombic, or oblong pyramidal, or prismatic of Mohs ; the rhomboedral of Mohs, or hexagonal of Naumann ; and the monoklinoedral, diklinoedral, and triklinoedral of the last mentioned writer. Some notion may perhaps be formed of the nature of these distinctions from the following representation : 5G. " If we conceive a square steeple with all the four sides of the walls and roof exactly alike, so that every slope and face which occurs on one side occurs similarly on the other three, we have before us a form belonging to the square pyramidal system. If, in- stead of this, we imagine a house of which the two ends are like each other, and the two sides also precisely like each other, but different from the former, this will belong to the oblong prismatic or rhombic system. If again we conceive a triangular pillar, as an ancient tripod, its three sides being similarly cut and ornamented, this will belong to the rhomboedral system. f In fact, its three faces may be terminated by slopes, which may meet and form an apex, resembling in all respects the apex of a rhomboedron. And if each of its three faces be formed into an edge, by planes sloping to the right and left, the form may be thus converted into a six- sided pillar with no loss of its regularity. On what principle does the goniometer of Wollaston operate ? What constitutes the latest improvement in crystallography ? Illustrate the views of Naumann on this subject? * A description of Dr. Wollaston's goniometer, with the mode of using it, illustrated by a diagram, will be found in Brande's Manuel of Chemis- try, vol. i. pp 10 13 ; or in Mrs. Lowry's Conversations on Mineralogy, 2d ed., vol. i. pp. 7175. t The rhomboedral and rhomoic systems are quite distinct. A rhombic prism has its base & rbomb ; a rhomboedron has all its sides equal rhombs. TESSULAR SYSTEM. 297 57. " If we conceive the form of the house of which we spoke, as representing the prismatic system, to be made less regular, by sloping its end walls in the direction of one end, we have the monoklinoedral system, and if the side walls slope also, we may have thus the diklinoedral and triklinoedral forms. "The tesseral or tessular system includes the forms which are derived from the regular solids of geometry, the cube, the octaedron, the dodecaedron. 58. " This distinction of different kinds of forms is one founded on the most general relation of their parts, and regulated by the degree and kind of their symmetry. The claim of priority in in- troducing this classification of forms has been a subject of contro- versy between Prof. Mohs and Prof. Weiss. However this question may be decided, the merit of this valuable simplification rests between them ; and all must allow the propriety with which Prof. Naumann, of Freiberg, the author of the best recent system of crystallography, has dedicated his work " to Mohs and Weiss, the Coryphsei of German Crystallographers.*" Explain the terms monoklinoedral and diklinoedral? To what two philosophe cryatallometrical systems ? To what two philosophers are we indebted for the introduction of the Isv * Report of Brit Assoc. 1832, pp. 328, 329. For a further explanation of the crystallographic system of Prof. Mohs, see Allan's Manual of Mine- ralogy, Introd., pp. 18, 19. Works relating to the department of Crystallography. Turner's Chemistry. Phila. edition, pp. 424 433. Webster's Manual of Chemistry on the basis of Brande's. 1 vol. 8vo. p. 9. Gorham's Chemistry. 1 vol. 8vo. pp. 8 21; with a plate illustrating the hypotheses of Wollaston and Daniell. Rome Delisle Crystallographies. 3 vols. 12 mo. 1783. Huay Crystallographie. 2 vols. 8vo. ; and an astlaof 84 plates, illustrating his views both synthetically and analytically. Bournon Traite de Mineralogie. 3 vols. 8vo. GEOLOGY. 1. GEOLOGY is a science exclusively of modern origin, pre- senting to our notice a series of facts and deductions resulting from researches almost entirely of a recent date. It relates to bodies, multitudes of which must necessarily have attracted the attention of mankind in all ages and countries, and many of whose properties have been frequently and closely investigated ; but it is the peculiar purpose of this branch of philosophy to develope the relations of natural substances as contributing to form the ter- restrial globe ; and hence the interest or importance of any given object, as a block of granite or marble, a nodule of flint, a petri- fied shell, a fragment of fossil bone, or any other natural produc- tion, is not decided on by the geologist with reference to its chemical composition or peculiar structure, simply considered ; but chiefly according to the indications it may afford concerning the mode of its derivation, and the situation it originally occupied, as composing a part of the crust or exterior of the earth. 2. The proper object and design of geology, therefore, must be the study of the general structure of what may be termed the shell of the terrestrial globe ; for though speculations relative to the nature of the internal strata, or even the nucleus of the mass, are not wholly inadmissible, yet they must ever be regarded as of secondary importance, and should be no further pursued than they are warranted by those facts and appearances which come imme- diately under our observation. This consideration, however, was entirely lost sight of by those earlier writers, who either incident- ally or professedly treated of the structure of the earth. It would be profitless labour to pursue at length the reveries of a host of bold theorists, who sprung up between the period of the revival of learning in Europe and the middle of the last century ; and whose systems of cosmogony, as they vainly styled them, have by more sober inquirers been justly stigmatized as romances, indebted for their existence to the prolific powers of imagination. 3. But while so many philosophers were busily employed in endeavouring to erect systems of cosmogony on the basis of their own most imperfect knowledge of the nature of mineral bodies, or drew their ephemeral theories solely from imagination, there were some who more wisely applied themselves to the observa- To what era in philosophy does the science of geology pertain ? What is the peculiar province of this science? How does the geologist differ from the chemist or mineralogist in his es timate of a natural object? What part of the globe constitutes the proper object of geological inves* tigation ? How are theoretical speculations to be regarded in geology ? What name was griven to geological theories before the period of exact observation ? 898 THEORIES OF LEIBNITZ AND LEHMAN. 299 tion of nature, and to the collection of correct iifformation relative to the productions of the mineral kingdom in general, and espe- cially concerning those fossils which exhibit traces of having originated from organization. 4. Bernard Palissy, a potter of Saintes, towards the end of the sixteenth century, is said by Fontenelle to have been the first who ventured to assert in Paris, in opposition to the prevailing opinion, that petrified shells were the remains of testaceous animals that had formerly lived in the sea, and that all these were not depo- sited at the universal deluge. He wrote on the Origin of Springs from Rain-water, and other scientific works ; and he had the merit of displaying much juster views of the operations of nature than most of his contemporaries, though his ideas met, in his own time, with a very faint reception. Similar notions were ad- vocated by Nicholas Steno, a Dane, who became professor of anatomy at Padua in Italy, in 1669 ; and Hooke and Ray, in Eng- land, distinguished themselves by opposing facts to visionary theories. 5. Leibnitz, in his Protogaea, published in 1680, advanced the bold hypothesis, that the earth was originally a burning luminous mass, the gradual refrigeration of which produced the primitive rocks, forming at first a solid crust, and this being ruptured, owing to irregular contraction, the fragments fell into the universal ocean formed by the condensation of vapours on the surface of the globe. He proceeds to trace the production of inundations, convulsions, and attrition of solid matter, by its subsequent deposition constituting the various kinds of sedimentary or stratified rocks. Hence, he observes, may be conceived a double origin of primitive masses : (1.) By cooling after igneous -fusion ; (2.) By re-concretion from aqueous solution.* " Here," says Mr. Conybeare, " we have distinctly stated the great basis of every scientific classification of rock formations."! The grand feature of the theory propounded by Leibnitz, relative to the candescent state and gradual cooling of the earth, was adopted not only by Whiston, but likewise more recently by Buffon, Deluc, and other theorists. 6. Among those men of science who contributed to the im- provement of geology, by their researches into the actual struc- ture of the earth's crust, was Tilias, a Swede ; who, aware of the importance of an exact knowledge of mineral bodies, published Who is said to have first made collections of fossil remains ? What Danish and English writers followed a similar coarse ? What view of the cause of rock formations was taken by Leibnitz? How does that view correspond with the present received opinions? What Swedish writer early contributed to the stock of facts relating to geology ? * " Unde jam duplex origo intelligitur primonim corporum, una, cum ab ignis fusione refrigescerent, altera, cum reconcrescerent ex solutione aqua- rum." t Progress, Actual State, and Ulterior Prospects of Geological Science, in Report of British Association for 1832, p. 368. 300 GEOLOGY. Hn 1750 several typographical descriptions illustrative of the geo logy of certain districts in Sweden. He was followed by Leh- man, a German mineralogist, director of mines in Prussia, who, in an Essay towards a Natural History of the Strata of the Earth, 1750, proposed a division of mountains into those formed before the creation of animals, and containing no fragments of other rocks ; mountains which were derived from the partial destruction of the primary rocks by a general revolution ; and those which resulted from local revolutions, and in part from the Noachian deluge. 7. Many other writers now appeared, who advantageously directed their attention to the investigation of particular topics connected with this subject; as the causes and phenomena of earthquakes and volcanos, the formation of deltas or low tracts at the mouths of rivers, the actual structure and position of the mineral strata, and the description of fossil remains of animal or vegetable origin. Among those who rendered important services to the cause of science by advancing general views of the theory of the earth, were Dr. James Hutton, of Edinburgh, and Profes- sor Werner, of Freyberg, in Saxony. These celebrated philoso- phers produced systems, in one respect, diametrically opposite to each other ; for while Hutton attributed the formation of the older rocks entirely to the agency of fire, Werner insisted that they originated from solution in a liquid. 8. The German geologist deserves the credit of having directed the attention of his pupils to the constant relations of mineral groups, and their regular order of superposition ; distinguishing the classes of primary rocks, or those destitute of organic remains, as granite and gneiss ; transition or secondary rocks, formed from the disintegration of the preceding, and occasionally exhibiting traces of organic remains, as grey wacke, a mechanical compound of agglutinated fragments ; floetz or tertiary rocks, including the coal strata, chalk, and freestone, some of which abound in organic relics ; and besides these, alluvial strata and volcanic rocks, the latter of which he seems to have regarded as of little importance, for he asserted that in the primeval ages of the world there were no volcanos. 9. The great merit of Hutton consists in his having demon- strated the igneous origin of basalt, and other trap rocks ; the high probability that granite is derived from the same source ; and that the other primary non-fossilliferous rocks have been more or less subjected to the agency of fire. " The ruins of an older world," said Hutton, " are visible in the present structure of our planet, and the strata which now compose our continents have been once beneath the sea, and were formed out of the waste of What was the division of mountains proposed by Lehman? What two writers attempted to reduce to geological systems the obser- vations of naturalists before the end of the eighteenth century? What is the difference of their views ? Who formed the division of rocks into primary, secondary, and tertiary ? To what peculiar merit is the English theorist entitled ? THEORIES OF THE EARTH. 301 pre-existing continents. The same forces are still destroying, by chemical decomposition or mechanical violence, even the hardest rocks, and transporting the materials to the sea, where they are spread out, and form strata analogous to those of more ancient date. Although loosely deposited along the bottom of the ocean, they become afterwards altered and consolidated by volcanic heat, and then heaved up, fractured and contorted."* 10. The theory of Hutton was admirably illustrated and ably supported by Professor Playfair, of Edinburgh, while it was assailed by Murray, Kirwan, Deluc, and others, a violent contro- versy being maintained between the partizans of Werner, who were called Neptunists, as ascribing the formation of all rocks to water; and those of Hutton, styled Vulcanists, because they attributed the original formation of rocks to fire. The Neptunists, for a time, constituted by much the more numerous party ; but in the course of these discussions, it was at length perceived that speculation had, on both sides, been carried further than was war- ranted by the extent of existing information ; and that while neither the theory of Werner, nor that of Hutton, could be consi- dered as affording an explanation of all the phenomena, or making near approaches to perfection, there were many points with re- spect to which the researches and observations of both these phi- losophers contributed to the extension of our knowledge, and the improvement of the science. 11. "A new school at last arose, who professed the strictest neutrality and the utmost indifference to the systems of Wer- ner and Hutton, and who resolved diligently to devote their la- bours to observation. The reaction, provoked by the intemperance of the contending parties, now produced a tendency to extreme caution. Speculative views were discountenanced ; and through fear of exposing themselves to the suspicion of a bias towards the dogmas of a party, some geologists became anxious to entertain no opinion whatever on the causes of phenomena, and were in- clined to scepticism, even where the conclusions deducible from observed facts scarcely admitted of reasonable doubt. 12. " But although the reluctance to theorize was carried some- what to excess, no measure could be more salutary at such a mo- ment than a suspension of all attempts to form what were termed theories of the earth. A great body of new data was required, and the Geological Society of London, founded in 1807, conduced greatly to the attainment of this desirable end. To multiply and record observations, and patiently to await the result at some fu- What did Hutton suppose to have been the origin of the present conti- nents ? Who have illustrated the theory of Hutton? What course was adopted to free the science of geology from disputes about theories ? What was the effect of that course ? * Lyll's Principles of Geology, 3d ed., 1834, vol. i. pp. 88, 89; from Hutton 's Theory of the Earth- 20 302 GEOLOGY. ture period, was the object proposed by them ; and it was their favourite maxim, that the time was not yet come for a general system of geology, but that all must be content for many years to be exclusively engaged in furnishing materials for future gene- ralizations. By acting up to these principles with consistency, they in a few years disarmed all prejudice, and rescued the science from the imputation of being a dangerous, or at best but a visionary pursuit."* 13. One train of research which was now pursued with great ardour, and which contributed much to the improvement of science, was respecting the nature of the organic remains, which were found imbedded in various strata in different parts of the world. Cuvier, the celebrated anatomist and zoologist, professor of natu- ral history at Paris, acquired great distinction by the number, accuracy, and importance of the discoveries which he made rela- tive to the generic and specific characters of the animals, frag- ments of whose bones, and other constituent parts, occurred to notice in the course of his long and laborious investigations. He ascertained that numerous living beings of different classes, which hav,p no existing analogues, once inhabited the surface of the globe ; and that the relative priority of the several strata might, to a certain extent, be inferred from the characters of the organic remains included in them. 14. Among the recent cultivators of this branch of science besides Cuvier, may be named Alex. Brongniart, Lamouroux, Lamarck, Deshayes, Marcel de Serres, Brocchi, Goldfuss, Parkin- son, Buckland, Conybeare, J. S. Miller, Mantell, Lonsdale, Say, Morton, and Harlan, who devoted their attention chiefly to fossil- ized animal remains ; and Adolphe Brogniart, Witham, Lindley, and W. Hutton, whose investigations have been especially directed to botanical oryctology. The results of their researches relative to these subjects, and those of other geologists concerning the mineralogical structure and position of rocks and mountains, and the modifying influence of existing causes on the surface of the earth, have greatly contributed to the augmentation of our know- ledge of the nature and arrangement of the superficial strata of the planet on which we dwell, which must be regarded as the only sure foundation of a true system of geognosy, which may verify or overturn the conjectural speculations of those philoso- phers who wrote during the infancy of the science. 15. " When we compare the result of observations in the last thirty years, with those of the three preceding centuries, we can- To what particular branch of the subject were inquiries directed ? Who took the lead in those researches ? What has been the effect of the inductive observations of modern phi- losophers ? What estimate is to be put upon the results of these inquiries compared with those of former years? * tyell'g Principles of Geology, vol. i. pp, 102, 103, I PROGRESS OF GEOLOGICAL SCIENCE. 303 not but look forward with the most sanguine expectations to the degree of excellence to which geology may be carried, even by the labours of the present generation. Never, perhaps, did any science, with the exception of astronomy, unfold, in an equally brief period, so many novel and unexpected truths, and overturn so many preconceived opinions. The senses had for ages declared the earth to be at rest, until the astronomer taught that it was carried through space with inconceivable rapidity. In like man- ner was the surface of this planet regarded as having remained unaltered since its creation, until the geologist proved that it had been the theatre of reiterated change, and was still the subject of slow but never-ending fluctuations. 16. The discovery of other systems in the boundless regions of space was the triumph of astronomy ; to trace the same system through various transformations to behold it at successive eras adorned with different hills and valleys, lakes and seas, and peo- pled with new inhabitants, was the' delightful meed of geological research. By the geometer were measured the regions of space, and the relative distances of the heavenly bodies; by the geolo- gist myriads of ages were reckoned, not by arithmetical computa- tion, but by a train of physical events a succession of pheno- mena in the animate and inanimate worlds signs which convey to our minds more definite ideas, than figures can do, of the immen- sity of time."* 17. " By the discoveries of a new science, (the very name of which has been but a few years ingrafted on our language,) we learn that the manifestations of God's power on earth, have not been limited to the few thousand years of man's existence. The geo- logist tells us, by the clearest interpretation of the phenomena which his labours have brought to light, that our globe has been subject to vast physical revolutions. He counts his time, not by celestial cycles, but by an index which he has found in the solid framework of the globe itself. He sees a long succession of monuments, each of which may have required a thousand ages for its elaboration. He arranges them in chronological order, ob- serves on them the marks of skill and wisdom, and finds within them the tombs of the ancient inhabitants of the earth. 18. He finds strange and unlooked-for changes in the forms and fashions of organic life during each of the long periods he thus contemplates. He traces these changes backwards through each successive era, till he reaches a time when the monuments lose^all symmetry, and the types of organic life are no longer seen. He has then entered on the dark age of nature's history ; and he closes the old chapter of her records. This account has so much What two great errors have astronomy and geology removed ? What discoveries have they respectively effected ? What is the relative nature of organized beings at present compared to that of forirar geological periods ? * Lyell's Principles of Geology, vol. i. pp. 106, 107. 304 GEOLOGY. of what is exactly true, that it hardly deserves the name of figura- tive description."* Figure and Magnitude of the Earth, its Mean Density, Superficial Conformation and Structure. 19. Before we proceed to describe the present state of the crust of the earth, and investigate the probable causes of its ori- gin and structure, with the nature of the strata or more irregular masses of which it is composed, it will be requisite to notice those facts concerning the general figure, dimensions, and den- sity of the terrestrial globe, and of the contour of its surface, as a body of land and water, for a knowledge of which we are in- debted to the researches of astronomers and geographers. 20. That the figure of the earth is spherical, or rather spheroidal, though a matter of dispute among ancient philosophers, and still disbelieved by the vulgar, is now admitted as an incontestable truth by all well informed persons. The curved surface of the sea when viewed from the shore, and the observation that the upper rigging of an approaching ship becomes visible to a distant spectator before the hull comes in sight, while the hull first dis- appears when the vessel is receding, prove that the object in question must be moving in the circumference of a great circle. 21. A similar conclusion may be drawn from the changing aspect of the heavens to an observer travelling from north to south. For though the stars and the constellations they form will be found to maintain the same relative positions with respect to those around them, and the points on which the celestial dome appears to revolve remain unaltered, yet the angle which its axis of revolution forms with the horizon continually lessens ; and thus any star, which at the place whence it started, seemed to the ob- server to have reached its greatest elevation to the south of the point directly above his head, now that he has altered his position, will appear, when highest, on the north of that point ; clearly in- dicating that his path on the earth's surface has not been a right line, but a curve, of which the convexity is turned towards the sky, corresponding, in fact, more or less, with a meridian of lon- gitude. The- appearance of the moon when eclipsed, likewise furnishes demonstrative proof of the spheroidal figure of the earth, for lunar eclipses are caused by its circular shadow inter- cepting the light of the sun from the moon's disk. What geographical subjects are connected with geological science? What evidence have we of the spherical form of the earth? What astronomical observations demonstrate this fact ? What particular celestial phenomenon occur in going from a north to a south latitude ? * Discourse on the Studies of the University, by Adam Sedewick, M.A F.R.S., Woodwardian Professor, and Fellow' of Trin. Coll. mb., 1834, pp. 25, 26. FIGURE OF THE EARTH. 305 22, It has been found, however, both from astronomical and geodesical observations, that the earth is not a perfect sphere, but that its figure is that of an oblate spheroid, or such a solid as would be formed by the revolution of a fluid mass in open space. Huygens and Newton deduced the real figure of the earth from the doctrine of central forces of bodies revolving in circles, and their conclusions were subsequently verified by actual mea- surements of degrees of the meridian in various latitudes. It appears, however, that though the polar diameter of the earth is certainly smaller than its equatorial diameter, the exact difference between them has not yet been accurately ascertained. It has been estimated by some at ,^-j part of the equatorial axis, by others at -^{-^ part; but Professor Wallace says: " We may as- sume, without sensible error, that the equatorial axis is to the polar as 334 to 333 ; the difference, therefore, of the serniaxes, compared with the equatorial radius, will be 1 part in 334. The fraction of ^T, that is, the difference of the semiaxes divided by the equatorial radius, is called the compression of the earth at the poles."* 23. The determination of the figure of the earth leads to con- clusions respecting its mean density, which also has within cer- tain limits been sufficiently ascertained. Sir Isaac Newton, rea- soning on the supposition of uniform density in the earth, esti- mated its compression at the poles as -^\^ of its diameter. Now, since experiment has demonstrated that the compression is less, In what manner do eclipses of the moon demonstrate the spherical form of the earth ? What is the true figure of the earth? What is the relation between the equatorial and polar diameters of the earth ? What has been assigned by Newton as the compression of the earth at the poles on the supposition of a uniform density ? * Murray's Encyclopaedia of Geography, 1834, part ii. b. i. ch. 19, p. 128. " As the earth has a movement of rotation about its axis, all its parts will be animated with a certain degree of centrifugal force, which must be more or less considerable as the parts approach or are distant from 'ha axis. Under the equator will be the points of greatest distance from iho axis, and the centrifugal force directly opposed to that of weight or gravi- tation, ought to reduce the latter there more than at any oij^r place ; and at parts intermediate between the poles and the equator, the diminution of weight ought to become less sensible, in proportion as they are nearer the poles. At either pole the centrifugal force will vanish, and bodies will have the same weight as if the earth were at rest. " As gravity must be normal at the surface of the sea, and as it is the resultant of terrestial attraction and centrifugal force, it will be obvious that it must vary at different places; and that if the earth wns originally a fluid.lt could not, in consequence of its rotation, preserve the form of a sphere, but that it must assume that of a flattened spheroid, which would be generated by the revolution of an ellipsis round its smaller axis. This also is demonstrated by experience, and that the flattening at the poles renders the axis l-310th less than the diameter at the equator." Francfp.nr Tr&Mde Micaniqme EUmenlaire, 1825, pp. 287, 288. See Scien- tific ClassBook.pt. i. Mechanics, Nos. 10G, 107, and 114 to 122. a 0-3 306 GEOLOGY. amounting at most to ^ it may be concluded from the observa- tions of Clairault, that if the earth is a spheroid of equilibration, it is denser in the interior than at its surface ; and from the experi- ments of Dr. Maskelyne and Mr. H. Cavendish,* it has been inferred that the mean density of the earth is about five times that of water, and therefore double that of the substances which com- pose the crust of the earth, collectively considered. 24. Since then the mean density of the terrestrial globe is so much superior to that of its superficial strata, it follows that the interior or central parts must be composed of more dense mate- rials than the exterior. On a subject so open to speculation as the constitution of the nucleus of the earth, a variety of conjec- tures, as might be expected, have been hazarded. The superior density of the interior parts of the earth compared with the exte- rior, has induced some to conclude that the nucleus of the earth must consist of some substance or substances naturally possess- ing high specific gravity, like certain of the metals. " It can be neither gas nor water," says Dr. Bertrand, " which constitutes the interior mass, nor yet the heaviest stony substances with which we are acquainted, for on this last supposition, the entire spheroid would have but one-third or one-fourth of the weight which has been attributed to it from calculation ; therefore it must be composed of matter as ponderous as the heaviest metals."f 25. This ingenous speculator, however, in reprobating the hy- pothesis of a fluid or gaseous nucleus of the earth, has entirely neglected the consideration of the relative compressibility of elas- tic fluids compared with bodies which on the surface of the earth possess superior density. Mr. Colebroke, in a paper published in Brande's Journal of Science, advanced some curious and interest- ing speculations on the internal portions of the earth, designed to show that they may consist of air and water, reduced by compres- sion to extraordinary degrees of density. He observes, that " At a certain assignable depth water may have a density greater than that of those solids which are most abundant in the crust or shell of the terrestrial globe. Hence it would follow that water at a very great depth would be capable of floating bodies which at the surface sink by their superior weight, provided density and spe- cific gravity increase much less rapidly in the solid than in the liquid, unde^corresponding degrees of compression. 26. Let a sphere now be supposed, having the same mean tem- perature of its mass, and exclusively composed of gas ; for in- What did Maskelyne and Cavendish demonstrate in regard to the mean density of the globe? To what-supposition lias thie result led ? What were Bertrand's views of this subject? What are the calculations of Colebrooke on the compressibility of air and water ? When might heavy solids be found to float in water ? * See Scientific Class Book, pt L pp. 40, 41. t Lett ur Ifis Rev- du Globe, p. 40. STRUCTURE OF THE EARTH. 307 stance, atmospheric air. It can be conceived that this gas, more compressible than a liquid, may in obedience to the power of gra- vity, acting directly and likewise mediately, by superincumbent pressure, be so distributed in the sphere, as that the density and consequent weight of the compressed gaseous fluid at the centre of the sphere, and to a certain extent around, will be greater than that of the liquid in a like position within the globe before men- tioned. It would be capable then of sustaining, in a liquid form, water introduced into it. Let these suppositions be combined, and a ball be next imagined, composed of a gaseous fluid, and of a liquid with solids interspersed. 27. It is easy to conceive the relative compressibility of these substances, and the actual compression of them to be such that the entire portion around the centre may be occupied by highly condensed gas, encompassed by a liquid mass, which is pervaded by a gaseous fluid, both decreasing in density upwards ; and beyond the liquid surface surrounded by an atmosphere consisting of gas penetrated by aqueous vapour. Solid substances sparingly scat- tered in such a fluid ball would float at a great depth ; but the magnitude of cohesive masses, and the abundance of them, may be imagined such, that they may be fast locked and fixed together, in the manner of field-ice, at the same time that the weight of them is such as would float them were they loose, like an iceberg, with a relatively small portion of the floating mass emergent. In a word, a solid crust might exist, sustained by the water in which it is immersed, at the same time that the irregular and uneven surface of the cohesive mass emerges in part, while other portions are submerged."* 28. Leslie instituted some important experiments on the compressibility of different kinds of matter, from which he drew very remarkable conclusions, deeply affecting the subject under consideration. He computed that air under the law of uniform condensation would become as dense as water at the depth of 33J miles, and that at a further depth of 163J miles, it would acquire the density of quicksilver. Water at the depth of 93 miles would be compressed to half its former bulk ; and at the depth of 362^ miles would be as dense as quicksilver. Even marble itself, subjected to its own pressure, would become twice as dense as before, at the enormous depth of 2871 miles. Air, What would be the density of air compared with that of water, suppos- ing its compressibility uniform, if compressed with a force of 826 atmos- pheres ? (See Scientific Class Book, pt. i. p. 154.) How may we conceive the crust of the earth to be disposed in regard to its condens'ed liquid ingredients? At what depth beneath the surface of the ocean would a mass of air, carried from the surface, have a density equal to that of water ? At what depth did Leslie suppose that water would have the same den- sity as quicksilver? * On Fluidity ; and an Hypothesis concerning the Structure of the Earth. Journ. of Science, voL ix. pp. 52 61. 308 GEOLOGY. however, from its rapid compressibility, would acquire the same density with water, sooner than the latter fluid would reach the condensation of marble. If we calculate for a depth of 395|. miles, or about a tenth part of the radius of the earth, we shall find that air would attain the astonishing density of 101960 bil- lions ; while at the ame depth water would attain but the density of 4.3192, and marble only that of 3.8025. At the centre of the earth air would reach the inconceivable density denoted by 7G4, with 166 ciphers annexed; while water would be condensed 3,009,000, and marble acquire the density of 1 19. 29. "Such are the prodigious results deduced from the law of gravitation, even supposing the structure of the globe were uniform. But if we take into the estimate the augmented power from condensation, the numbers would become still more stupen- dous. It follows, therefore, that if the great body of our earth consisted of any such materials as we are acquainted with, its mean density would very far surpass the limits assigned by the most accurate investigations. It seems, therefore, to follow con- clusively, that our planet must have a very widely cavernous structure, and that we tread on a crust or shell, whose thickness bears but a very small proportion to the diameter of its sphere. 30. Physical science can extend her prospects to the farthest verge of possibilities, but chemistry, even in its present advanced stage, fails altogether in aiding inquiry ; and the various hypothesis framed by geologists are built with snch scanty and slender ma- terials, as to furnish no safe guidance through these boundless speculations. It is evident that immense compression would totally derange the powers of elective attraction, and change the whole form and constitution of bodies. When air becomes denser than gold, it is hard to conjecture what transmutations this plastic fluid must undergo. The bowels of the earth may contain sub- stances thus transformed, bearing no longer any resemblance to their aspect on its surface. 31. Observations relative to the temperature of the earth, and the probable sources whence it is derived, might be expected to lead to some reasonable conclusions relative to its central struc- ture and composition. This subject may be regarded as apper- taining more directly to the science of pyronomics, than to geology, and it has accordingly been generally noticed in the pre- ceding volume of this work;* but is so intimately connected with the topics under discussion, as to require more particular attention. 32. That the internal parts of the earth are more highly heated than its surface, and that their temperature depends on other causes What change of properties may we conceive to result from the high de- gree of compression arising from the liquid of which the earth is supposed to be constituted ? * See Scientific Class Book, pt. i. pp. 280285. INVARIABLE STRATUM. 309 than the influence of the sun's rays, may naturally be inferred from the phenomena of volcanos and thermal springs, which have in some degree attracted the attention of philosophers in early times; but. the doctrine of central heat, adopted to account for these and other analogous occurrences, has recently derived strong confirmation fr^u experiments and observations, instituted for the express purpo^ of ascertaining how far it is consistent with the general economy of nature. 33. In 1671, Cassini, the first distinguished astronomer of that name, noticed that in the caves under the observatory at Paris, the temperature had remained unaltered during a whole year ; and in 1730, Lahire made a similar observation. Forty years later the Count de Cassini first perceived the full importance of this phe- nomenon; and in 1771, he commenced a series of experiments for the purpose of elucidating it. At length, on the 4th of July, 1783, he, in conjunction with Lavoisier, placed in the caves of the observatory a very sensible thermometer, so arranged as to show the slightest variations of temperature that might take place. It was fixed 30.6 yards below the surface, and imbedded in sand ; and the observations of Cassini himself, with those sub- sequently made by Bouvard for thirty-two years, showed that during more than half a century the temperature of the caves has remained permanent at 11.82 of the centigrade thermometer, the slight oscillations which occurred never amounting to more than 25 centiemes of a degree above or below 11. 82, and being apparently owing to accidental causes. The mean annual tem- perature of the air at Paris is only 10. 6, so that the constant temperature of the earth there 30.6 yards beneath the surface, exceeds it by 1.2 cent., or 2. 16 of Fahrenheit. 34. Hence it appears that the depth corresponding to an aug. mentation of temperature amounting to 1 is about 25 1 yards ; and admitting that the temperature increases uniformly with the depth, the heat must be equal to that of boiling water at the depth of 2542 yards below Paris. Observations thus exact and long continued have unfortunately been made only at the Parisian observatory, but from the nature of the results it may be inferred, that this stability of subterranean temperature, is not an accidental phenomenon, but depends on general causes, and therefore it may be concluded that in all places, at a given depth beneath the sur- face of the earth, there is a certain point at which the temperature remains constantly the same, being uninfluenced by those causes which may effect the surface. What general truths may we deduce from the phenomena of volcanos and hot springs ? What facts were observed by Cassini in regard to this subject? What is the temperature of the caves of the Paris observatory in degrees Fah. ? How much variation is found there in the course of a year ? What is the mean temperature at the surface of the ground f If the interior heat increases uniformly, at what depth below the surface would be found the temperature of boiling water ? 310 GEOLOGY. 35. The series of such points of invariable temperature around the globe may be termed the invariable stratum, at which the influence of all those alternations of heat and cold, occasional or periodical, which might act on the superior soil, would be extin- guished. This stratum, however, cannot be considered as forming a regular curve, or maintaining a constant^istance from the sur- face ; for its depth and conformation musr^Be affected by the na- ture of the surface, as consisting of land or water, and as being diversified by plains, mountains, and valleys, and composed of materials more or less dense and compact. 36. A few observations only have been made relative to the variations of temperature which take place in the space between the surface and the invariable stratum. So far as they go, how- ever, they tend to show that the influence of the solar heat pre- vails in the summer months, and that of central heat in the winter, as might be expected. But the most important observations are those which have been made on the temperature of the earth below the invariable stratum. The prevalence of heat in mines had been noticed arid variously accounted for by philosophers, long before it was made the subject of direct experiment. Gensanne appears to have first discovered that the temperature of the earth increases with the depth below the surface, by means of thermo- metrical observations instituted in the lead mines of Giromagny, near Befort, in 1740; and in 1785, corresponding experiments were made by Saussure, in a mine at Bex, in the canton of Berne. In 1791, the subject occupied the attention of Humboldt, who made an extensive and interesting series of experiments in the mines of Freyberg. 37. In 1802, D'Aubuisson revived the important investigation, and since that time observations have been multiplied in the prin- cipal mines of Europe, in France, in Germany, and in England, while Humboldt, proceeding on his memorable scientific voyage, in 1798, examined the temperatures of the mines of America to the depth of 522 metres. 38. M. Cordier, in 1827, published an interesting memoir, on the temperature of the earth, (in Memoires du Mustum d'Histoire NaturelleJ) in which he collected the observations of others, to- gether with his own, and having classed and arranged them, drew from them some interesting general conclusions. He ascertained that after making due allowance for the heat in mines arising from the presence of miners, the combustion of lamps, and communi- cation with the atmosphere, the following results were established: 39. (1.) Below the invariable stratum, where the oscillations of surface heat are extinguished, the temperature remains per- fectly constant for given depths, without any variation for several What general inference may we derive from these facts ? Who first discovered the increase of temperature as we descend below the invariable stratum? What subsequent investigations of this subject have been made ? CONTRACTION OF THE EARTH. 311 years. (2.) That in all places where observations have been made below the invariable stratum, the temperature 'always goes on in- creasing with the depth. (3.) That the ratio of the augmentation of temperature, in descending below the invariable stratum, is different for different places. 40. M. Cordier considers that from 25 to 30 metres' depth may be assumed approximately as corresponding with an increase of temperature, amounting to 1 centessimal degree ; and therefore 1 of Fahrenheit may answer to about 15 yards. On the last suppo- sition of 1 F. additional for every 15 yards of vertical descent, it must follow that at the centre of the globe, supposing its mean semi-diameter 3956.8 miles and the temperature to increase uni- formly, it would then rise to 464,264 F. The temperature of 7000 F., which would be sufficient for the fusion of lavas and probably of all kinds of rocks and metals, would be found at the depth of about 60 miles. It is, however, uncertain what may be the mean thickness of the solid crust of the earth. Cordier imagines that it may not exceed 60 miles. Hence a strong pre- sumption arises in support of the inference, that the consolidation of the exterior crust is the effect of a gradual cooling. 41. If this is the case the consolidation must have commenced at the surface, and proceeded towards the interior; and therefore, contrary to the received opinions of geologists, the primitive rocks are more ancient in proportion as they are nearer the surface. It follows, also, that the strata ought to be arranged in the order of fusibility, or nearly so, some allowance being made for the inter- ruption of this order, owing to the rapidity of cooling at first, and to the influence of chemical affinity on the vast mass of the globe. 42. Another necessary consequence of the hypothesis is, a con- traction of the dimensions of the earth, through the diminution of its temperature, causing subsidence and approximation of the ex- terior crust, and consequent dislocation of its parts. This may account for the numerous cracks and fissures, and the irregularity of the disposition and inclination of the superior strata. But the subsidence not taking place regularly, would not produce a gene- ral, or very extensive change of level, though it might be suffi- cient to explain certain phenomena otherwise not easily ac- counted for : such as the apparent secular decrease of the water of the Baltic, and the alteration of level of the Mediterranean observed on the coast of Egypt. 43. The most important effect, however, of the contraction of What three general conclusions did Cordier derive from his investiga- tions ? At what depth might we probably find the temperature sufficient to maintain the metallic and rocky constituents of our globe in a slate ol' fusion ? Where must the consolidation of the globe have commenced on the sup- position of its having been once in a state of igneous fusion ? What consequence in regard to the bulk of the globe must arise from the gradual cooling of its surface ? 312 GEOLOGY. the bulk of the earth, is an acceleration of its rotatory motion. For such is the mechanical relation between the dimensions of the earth and its period of rotation, that if it undergoes contrac- tion of volume, the rotatory motion must be accelerated ; whence increase of centrifugal force, causing the level of the ocean to be raised a little between the tropics, and lowered in the polar re- gions, so that the northern parts of Europe and Asia would be gradually elevated above their former level with respect to the sea.* In this way the numerous islands of the Pacific Ocean may be supposed to be the summits of mountains belonging to a portion of submerged continent. 44. The same relation also affords the means of measuring the secular contraction, for the length of the day is an astronomical element of such importance that the slightest variation would be immediately detected. But observations sufficiently accurate ren- der it certain, that since the time of Hipparchus, or during the last twenty centuries, the length of the day has not varied by %%- of a second. Hence it necessarily follows, that if the contraction is proceeding, it must be at a rate almost infinitely slow. The amount of contraction, however, cannot safely be taken as a mea- sure of the loss of temperature. The cooling takes place under circumstances very different from those in which bodies are placed when exposed to the free action of the atmosphere, and the ordi- nary laws of contraction must be greatly modified by the enor- mous pressure at the depth of twenty leagues beneath the surface. 45. It has been found that the temperature of springs, as they issue from the earth, varies but inconsiderably at different seasons of the year ; and that in our hemisphere they attain their highest degree of heat in general about the month of September, and their lowest towards March, the difference of the two extremes being from 1 to 2 centig. From a table of the mean temperature of springs in different parts of the world compared with that of the air at the surface of the soil, collected from the experiments of different observers, by M. Pouillet, it appears that in the torrid zone, the mean temperature of the air is in general somewhat lower than that of springs ; but in the temperate zone the contrary appearances take place ; the springs are warmer than the air, their excess of temperature usually increasing with the latitude, so that at 60 or 70 degrees, from the accurate observations of Wahlen- What effect on the time of a diurnal revolution must the contraction of the earth produce ? What does astronomy teach in regard to the length of our present days compared with those of 2000 years ago ? How is the contraction of bulk in the earth probably effected by the present circumstances of its crust ? How is the temperature of springs found to vary from that of the air in the torrid zone ? How in the temperate zones ? * See Scientific Class -Book, pt. i. p. 57, Nos. 103 and 104 of Mechanics, for the manner of estimating centrifugal force, and observations on the consequences of its overcoming the force of gravitation. HOT SPRINGS OF ICELAND. 313 berg, it may be concluded that their temperature is from 3 to 4 centig. above that of the air. 46. Investigations of the heat of Artesian wells,* have brought to light some important results relative to the internal tempera- ture of the earth. M. Arago collected observations whence it appeared that the greater the depth of such wells, the higher is the temperature of the waters that flow from them. M. Fleuriau de Bellevue found that the temperature of the water at the bottom of an Artesian well, by the sea side, near Rochelle, 316 feet deep, was 16.25 centig. ; and the boring being afterwards continued to the depth of 369.5 feet, the temperature at the bottom was found to be 18. 12 centig., the mean surface temperature of the country being 11.287 centig.f 47. Though there are various circumstances that might occur to modify the temperature of springs, yet it must be inferred from the preceding observations that some springs display degrees of heat greater than could be supposed to be caused by the influence of the rays of the sun propagated through the superficial strata of the earth. This also still more evidently appears from the tem- perature of thermal waters, sometimes approaching to the boiling point. 48. The source of heat in springs or fountains of this kind has been the subject" of much controversy. Connected as they fre- quently are with volcanos, their temperature may naturally be imputed to volcanic agency ; arid when hot springs are found tra- versing cracks in strata not volcanic, attempts have been made to account for the phenomena by chemical combinations at incon- siderable depths ; but the salts usually found dissolved in these waters do not afford support to this theory, and Berzelius has shown it to be untenable with respect to the Carlsbad waters.:}: Numerous instances occur of the existence of thermal springs in tracts of country distant from any open or extinct volcanos. It may, however, be alleged that they may possibly communicate with some deeply-seated foci of volcanic agency; yet admitting such communication it would only tend to prove that volcanos, as well as thermal fountains, owe their origin to central heat. 49. Among the hot springs obviously connected with volcanos are. the Geysers in Iceland, the phenomena of which deserve to be noticed, as the extraordinary effects exhibited serve in some What light is thrown upon this subject by the examination of Artesian weHs ? What is sometimes found to be the temperature of hot springs ? What theories have been formed to account for the heat of thermal waters? To what common cause may volcanos and hot springs be referred ? * For an account of the nature of Artesian wells, see Treatise on Hy- drostatics, Scientific Class Book, pt. i. p. 144. t De la Beche's Geological Manual, 3d ed., 1833, 8vo.,p. 13; from Journ. de Geologie, torn. i. | Id. p.l7. 2D 314 GEOLOGY. degree to indicate the extent and magnitude of the power by which they are produced. "These intermittent hot springs rise from a large tract, covered to a considerable depth by a stream of lava, and where thermal water and apertures evolving steam are very common. The Great Geyser rises out of a spacious basin, at the summit of a circular mound, composed of siliceous incrustations, deposited from the spray of its waters. The diameter of the basin or crater in one direction is 56 feet, and 46 in another. In the centre is a pipe 78 feet in perpendicular depth, and from 8 to 10 feet in diameter, but gradual- ly widening as it opens into the basin. The inside of the basin is whitish, consisting of a siliceous incrusta- tion, and perfectly smooth, ajs are two small channels on the sides of the mound, down which the water makes its escape when filled to the margin. The circular basin is sometimes empty, but is usually filled with beautifully transparent water in a state of ebullition. 50. During the rise of the boiling water up the pipe, especially when the ebullition is most violent, and when the water flows over or is thrown up in jets, subterranean noises are heard, like the dis- tant firing of cannon, and the earth is slightly shaken. The sound then increases, and the motion becomes more violent, until at length a column of water is thrown up perpendicularly with loud explo- sions, to the height of 100 or 200 feet. After playing for a time like an artificial fountain, and giving off great clouds of vapour, the pipe is evacuated, and a column of steam then rushes up with amazing force and a thundering noise, after which the eruption terminates. If stones are thrown into the crater they are ejected What remarkable instance supports the theory of a volcanic cause for hot springs ? Describe the Great Geyser ? What is the appearance of the pipe or cavity whence the water is pro- tected ? In what manner does the projection of water from the Geyser take place? What succeeds to the column of water in this fountain ? TEMPERATURE OF THE ATMOSPHERE. 315 instantly, and such is the explosive force, that very hard rocks are sometimes shivered into small pieces. Henderson found that by throwing a great quantity of large stones into the pipe of Strocke, one of the Geysers, he could bring on an eruption in a few minutes.* The fragments of stone, as well as the boiling water, were thrown in that case to a much greater height than usual. After the water had been ejected, a column of steam continued to rush up, with a deafening roar, for nearly an hour ; but the Geyser, as if exhausted by this effort, did not give symptoms of a fresh eruption when its usual interval of rest had elapsed. "f 51. Sir George Mackenzie describes the continual discharge of water and steam from the Great Geyser, during its period of excite ment, as resembling the distant firing of artillery from a ship at sea ; and he estimates the height of the jet as being at least 90 feet. The temperature of the water in the pipe, when sufficiently high for observation, was found to be 209 Fahrenheit. There are several other alternating hot springs in Iceland, one of which, called the New Geyser, formerly an insignificant fountain, now explodes like that already described ; but most of these springs are of inferior magnitude to the Geysers. 52. The distribution of heat in large masses of water, as lakes and seas, is much more uniform than in the solid strata. This fact, ascertained by Saussure, by means of experiments on the lakes of Switzerland between 1777 and 1784, may be regarded as depend- ing on that property of water, in virtue of which it acquires its greatest density, a few degrees above the freezing point. More extensive observations, however, have shown, that while the temperature of water varies but little at different depths in the temperate zone, it increases with the depth in the polar seas ; and this augmentation of temperature in descending, may reasonably be supposed to depend on the influence of central heat. 53. The temperature of the atmosphere, like that of the sea in the equatorial regions, decreases generally with the distance from the surface. And hence extreme cold prevails at a great elevation. The tops of high mountains in the torrid zone are covered with perpetual snow, and M. Gay Lussac, in his famous aeronautic ex- pedition, having ascended about a league and a half above the city of Paris, experienced a depression of temperature 12 centig. below the freezing point. At greater heights the cold would become utterly insupportable. These circumstances depend chiefly on the What is the effect of throwing heavy bodies into this spring ? What temperature has the water in this case ? What is the relative uniformity of temperature in the solid and the li- quid parts of the globe ? How do waters vary in different latitudes ? What is the comparative temperature of air in high and in low situations 1 * Journal of a Residence in Iceland, p. 74. t Lyell's Principles of Geology, vol. ii. pp. 307309. | Mackenzie's Travels in Iceland. 316 GEOLOGY. absence of reflecting bodies in the higher regions, and the rarity of the air, which affords a free passage to the solar rays, deriving from them but an inconsiderable augmentation of temperature, 54. However, though the cold appears to increase with the height throughout the extent of the earth's atmosphere, it is proba- ble that there is a limit in space beyond which the temperature cannot descend. The earth and the other planets may be regarded as moving within a medium of uniform temperature, such as would exist within the sphere of uranus, if the sun and all the planetary bodies were removed. That such a temperature occurs in the regions beyond the atmosphere, may be inferred from various con- siderations. The innumerable stars scattered through the heavens, glittering with light as we behold them, cannot be imagined to be destitute of heat, and how feeble soever their influence, in con- sequence of their distance, they must produce some effect on bodies in surrounding space. 55. Admitting, then, that there is an elastic medium beyond the atmosphere of the earth, as seems to be proved by observations on the periodic revolutions of Encke's comet,* it must have a certain capacity for heat, like all other matter. But whether the temperature of the planetary spaces be caused by radiation from the stars, or be regarded as essentially belonging to the elastic medium, the mathematical investigation of the state of the surface of the earth proves that there must exist a fundamental temperature, indepen- dent of the sun or any sources of internal heat ; for otherwise, the superficial temperature would be very different, and its decrease from the equator to the poles incomparably greater than it is in reality. 56. If the earth revolved in a medium absolutely destitute of heat, the slightest variations in the sun's distance would occasion What may we suppose to be the conditions of the celestial spaces in re- gard to changes of temperature ? In what medium do the planets and comets probably move ? How is the existence of such a medium proved ? * The comet distinguished by the name of the German astronomer Encke, who first ascertained that it had a comparatively short period of revolution, appears to be gradually approaching nearer and nearer to the sun in each successive revolution, whence it follows that it must move in a resisting medium. Encke stated (in the Berlin Ephemeris, 1823) as the result of his observations, that the periodic time of this comet was shorter than that deduced from earlier investigations. Calculations were subse- quently made as to the effect of perturbations of the comet produced by its approach to the planet Jupiter, after making allowance for which, how- ever, it was found that the diminution of its orbit could only be accounted for by the existence of a resisting medium. " The magnitude of the re- sistance is such, as to dimmish the periodic time about l-10,000lh of the whole at each revolution, a quantity so large that there can be no mistake about its existence. The history of this discovery is undoubtedly one of the most curious that modern astronomy has presented." Prof. Airy on Astronomy, in Rep. of Brit. Assoc.for 1832, p. 163. See also Whewell's Astronomy and General Physics, Bridgwater Tr., b. 3, ch. iv. CENTRAL TEMPERATURE OF THE EARTH. 317 sensible changes of temperature, and the diurnal alterations would be fatal to organic life. These effects must be in some degree modi- fied by the presence of the atmosphere, yet the comparatively small variations of temperature which actually take place are in- compatible with the existence of a degree of cold in the planetary regions, much beyond the freezing point of mercury. On com- puting the amount of temperature which the medium without the atmosphere must possess, to account for the existing thermometri- cal state of the earth's surface, Baron Fourier found that the phenomena are such as would result from the supposition that the celestial spaces have a temperature equal to 50 centig., or 58 Fahrenheit below zero. It should be remarked, that this theory has been to a certain extent confirmed by the researches of M. Svanberg, a Swedish philosopher, who having investigated the temperature of the planetary spaces upon a principal different from that adopted by Fourier, arrived at nearly the same conclusion.* 57. All the phenomena of temperature, as respects the solid parts of the earth, the waters, and the atmosphere, seem consistent with the hypothesis of central heat; but there is an apparent ob- jection which demands some notice. It might be imagined that the intense heat of the nucleus of the earth is incompatible with the present temperature of its surface. But it has been demon- strated from mathematical investigation of the laws which regulate the propagation of heat, that there may exist, not merely at the centre of the earth, but even at comparatively small depths below the surface, a temperature sufficient to fuse the most refractory substances with which we are acquainted. f What consideration proves the existence of a uniform temperature in the planetary spaces ? What would be the effect of diurnal changes of tem- perature if the earth were in a medium absolutely cold ? What actual temperature did the computations of Fourier assign to the spaces beyond our atmosphere ? What objection has been raised to the theory of central heat ? * Foreign Review, vol. viii. pp. 311, 312 ; Pouillet Elemens de Phys. Ex. et de Meterologie, torn. ii. pp. 663 665. 6% 700 ; Berzelius's Annual Re- port to the Academy of Sciences at Stockholm for 1829 ; Edinb. Journ. of Science, vol. hi., New Series. t " The following are the most remarkable deductions made by Fourier from the analytical investigation of the hypothesis of an internal heat. Supposing the conducting power of the materials of the earth, to equal that of iron, and that the temperature increases by l-30th ot a centesimal degree for every metre of vertical descent, (about l-18th of a degree of Fahrenheit for every yard,) which is the rate indicated by observation, thfe enormous heat accumulated in the interior would cause an augument- ation of temperature at the surface, amounting only to a quarter of a de- gree above that which is due to the heating effects of the sun. This small addition to the effects of solar heat is in proportion to the conducting powers of tbe envelope, all other circumstances remaining the same ; con- sequently as the conductibility of the superficial materials of the earth is considerably less than that of iron, the augumentation of temperature just mentioned is estimated too high, and probably does not exceed l-30th of a centesimal degree. Hence the effects of a central heat are altogether in- sensible at the surface." Foreign Review, u. a. p. 313. 2D2 318 GEOLOGY. 58. The admission of an original state of igneous fusion of the materials composing the terrestrial globe, their gradual cooling from the surface towards the interior, and the existence during a very protracted period of a central nucleus still intensely heated, may be granted as probable not only as being supported by the evidence derived from the researches concerning the temperature of mines, springs, and waters in general, in various parts of the world, of which some account has been given but also because it will account for the structure and figure of the earth, as being a spheroid of revolution, constituting a mass of matter, the density of which increases towards the centre. 59. To the same cause may be attributed the existence of vol- canos widely distributed over the globe, and manifesting a com- mon and deeply-seated origin; and the occurrence of thermal springs having their sources far beneath the surface, and sometimes appearing at a distance from the craters of volcanos, though probably in general more or less connected with them in the bowels of the earth. To the evidence for the existence of central heat derived from these considerations, may be added the proofs, that in the temperate and frigid zones of the earth a temperature pre- vailed, at a very remote period, equal if not superior to the utmost beat of the torrid zone at present; and such as was adapted to call into existence^ profusion of organic beings, both in the animal and vegetable kingdoms, on a most gigantic scale. 60. " As there is great difficulty of conceiving any other than the igneous fluidity of our planet previous to the consolidation of its surface, and as fluidity seems essential to the figure of the earth, it has been suggested that the earliest transition from a liquid to a solid state, consequent on the radiation of heat, would take place at the equator, and that masses of the solidified crust would float upon the incandescent fluid beneath.* The fluid mass would necessarily be influenced by tides : therefore so long as the solidified crust was too thin to resist the effects of this cause, it would be broken up into fragments, the precursors of those of which the solid surface of our globe is every where composed." 61. When the surface of England is minutely examined, there is found scarcely any area of eight or ten square miles in extent which has not been fractured or broken up into minor portions, by causes, that have acted at various geological epochs. What is thus true of England is found to be also generally true of the whole sur- VVhat facts, besides the observed temperatures of the earth, favour the supposition of igneous fusion at the centre? What was formerly the temperature of the present northern frigid zone ? What proves such to have been its state in regard to heat? What part of the earth's surface may we presume to have been first so- lid, fied ? What appear to be the relative ages of the fractured portions of the earth's surface ? * Croizet et Jobert Recherches sur les Ossemenes Fossiles de Dep. du Puy de-Dome. 1828. SUPERFICIAL STRUCTURE OF THE EARTH. 319 face of our continents and islands, when examined with the neces- sary attention. Sometimes a more modern deposit may mask the surface broken into fragments, the former not having been yet acted on by disrupting forces ; but when rocks, on which such deposits rest, are exposed by denudation of any kind, either in ravines, or over a certain extent of horizontal area, they will be found fractured. 62. There must have been inequalities in the earth's surface from its earliest consolidation. The radiation of heat, and the ne- cessity of the exterior solid crust conforming to the fluid surface beneath, could not have done otherwise than produce them. Hence M. Elie de Beaumont's theory of the elevation ol mountain chains, which rests on the necessity of the earth's crust continually diminishing its capacity, notwithstanding the nearly rigorous con- stancy of its temperature, in order that it should not cease to em- brace its internal mass exactly, the temperature of which diminishes sensibly, while the refrigeration of the surface is now nearly in- sensible.* Influence of Existing Causes on the Structure and Conformation of the Surface of the Earth. 63. The terrestrial globe, the general dimensions of which have been already stated, is composed of various kinds of matter sub- sisting in the solid or fluid state, and encompassed by an atmos- phere of elastic or gaseous fluids, of uncertain extent, but gradually decreasing in density as it recedes from the earth's surface. The superficial distribution of land and water is extremely irregular, and the area covered by the latter far exceeds the space occupied by the former, which probably does not amount to more than a fourth part of the entire surface. A larger portion of dry land is found in the northern hemisphere than in the southern, that part of the globe which is to the south of the equator being chiefly covered by the sea, while to the north of the line sea and land are more equally distributed. 64. The surface of the earth exhibits abundance of obvious irregularities, or elevations and depressions, the land rising into mountains in some places, and sinking in others into glens and valleys ; and in the parts under the sea similar inequalities of level are found to exist. But though this diversity of configuration ap- pears sufficiently striking when viewed in detail, yet a little con- sideration will evince that these irregularities are quite unimport- Why is this circumstance not generally obvious ? What is Beaumont's view of the origin of mountains ? What is the relative area of land and water on the surface of the globe ? What is the form of the bottom of the ocean ? How are the irregularities of the earth's surface in comparison with its whole diameter? * De la Beche's Geological Researches, chap. iii. pp. 45, 46. 320 GEOLOGY. ant when estimated with reference to the magnitude of the ter- restrial spheroid. 65. The loftiest peaks in the world are supposed to be those of Dwalagiri and Chandradabani, in the Himalaya range of mountains north of Hindostan, said to be about five miles above the level of the sea; and on the opposite surface of the globe are the summits of Chimborazo, Illimani, and Sorata, in the ridge of the Andes, the height of which is probably somewhat more than four miles above the sea. The depth of the ocean beneath its common level, it is manifest, can only be calculated conjecturally, beyond those points which can be fathomed with the sounding line; but from calculations founded on astronomical data, Laplace inferred that its mean depth was a small fraction of 25 miles, the difference in the diameters of the earth, owing to the compression or flattening at the poles.* It has been variously estimated at between two and three miles ; and it may be reasonably concluded that the bot- toms of the lowest submarine vallies, or cavities in the bed of the ocean, do not reach further beneath its surface than the summits of the loftiest mountains extend above that level. 66. If, then, five miles be assumed as the height of the most exalted protuberances, and also as to the depth of lowest depres- sions on the solid surface of the earth, the utmost inequalities of level cannot exceed ten miles, which will be little more than -l_ part of the diameter of the globe. But the sea covering so large a portion of the exterior of the earth, causes the whole mass to as- sume the form of a nearly perfect spheroid, irregularly dotted with relatively minute points, the most considerable of which protrudes about T g^o- of the earth's diameter above the common level of its surface. Hence, our planet viewed from the moon, must, like that satellite, exhibit a circular outline. 67. The uneven figure of the earth's surface has been compared to the little risings and indentations on the rind of an orange, but with reference to the diameters of the two bodies, the irregularities What is the actual height of the highest mountains? What is the probable depth of the lowest ocean vallies ? How would the earth's surface appear when viewed from the moon or a planet ? * " On a regarde long-temps la profondeur de la mer comme incalcula- ble, on la disait immense. II est vrai que par rapport a nous elle est tres- grande, qu'elle est incommensurable mecaniquement par nos appareils les plus perfectiones, et quoique 1'etendue des regions marines dont on n'a pu trouver le fond soit tres-vaste, on ne doit pas en conclure que ce fond n'existe point. L'astronomie moderne, aidee des grandes lois de la gravi- tation universelle, nous a devoile ce mystere, et M. de Laplace a demon- tre, par 1'influence que la lune et le soleil exercent sur notre planete, que la profondeur moyenne de la mer ne pouvait depasser 8000 metres, (envi- ron 4000 toises.) Ainsi les plus halites montagnes s'elevent au-dessus de la surface des eaux, a la meme distance que les abimes de 1'ocean s'en- foncent dans 1'interieur de la terre." Resume d'un Cours EUmentaire de Geographic Physique, par J. V. F. Lamouroux, D.E.S., Prof. d'Hist. Nat a Caen, 1821, 8vo. p. 166. IRREGULARITIES OF THE EARTH*S SURFACE. 321 of the latter exceed those of the former beyond all proportion ; for if the mountains and valleys of the earth were modelled according to the exact ratios of their respective heights and depths, on the surface of an artificial globe one foot in diameter, they would be hardly, if at all, perceptible. 68. The surface of the earth both above and beneath the level of the sea presents a considerable variety of conformation and arrange- ment. The higher parts of the land consist of rocks and mountains, disposed in ridges, like the Alps, the Pyrenees, and the Andes, or in detached peaks and headlands, as the Peak of Teneriffe, and the Table Mountain at the Cape of Good Hope. Low lands may form extensive plains, or wide sandy deserts, and marshy tracts, or lines of coast descending to the level of the sea. Ravines, hollows, and valleys, may occur at various heights, rivers sometimes flowing through them to their termination in lakes and seas. As to the form of the solid surface covered with water, some interesting circum- stances have been observed. There can be no doubt but the bed of the ocean varies in level in some measure like the dry land. The numerous islands scattered through the deep are obviously the higher parts of submarine eminences, those portions of which that are under water sometimes forming sloping banks, and sometimes abrupt and perpendicular precipices. The declivities, however, except around coral islands, are not probably, in general, very steep. t 69. " The soundings round coasts," says Mr. De la Beche, "present us with no lines which we might consider to be those of valleys, but with extensive areas, which would, if raised above the level of the sea, form great plains, with here and there some minor elevations and deeper depressions', the latter generally in the form of basins. There are indeed some long trough-like cavities in the North Seas, named the Silver Pits, but they present us with nothing like a system of valleys resembling those on dry land. If the British Islands were elevated one hundred fathoms above the level of the ocean, and thus joined to the continent of Europe, they would be surrounded by an extensive area of flat land ; for the fall from the present coasts to the new sea-coast would be generally so gradual as to present to the eye one great plain."* The area thus described, in which the sea is in general about one hundred fathoms in depth, is bounded on the west and north-west by a line inclu- ding the British islands, and passing round them from the coast of France to that of Norway ; and terminating towards the open sea by a slope, sinking in a comparatively rapid manner into deep water. How may the slight irregularities of the earths surface be illustrated ? How may we regard the islands of the ocean ? Of what form are generally found the bottoms of seas in the neigbour- hood of continents and islands ? How is this illustrated in the north sea and other parts of the ocean west of Europe ? * Geolog. Researches, pp. 189, 190. 322 GEOLOGY. 70. It is a curious fact, that there are continental portions of the earth's surface considerably below the common level of the ocean. MM. Parrot and Engelhart appear to have made the discovery, that the Caspian Sea and Lake Aral are beneath the level of the Mediterranean ; and M. de Humboldt ascertained that this depres- sion extends to an extensive territory, about 18,000 square leagues in surface. This tract forms an immense basin, the lowest part of which is occupied by the Caspian Sea. The surface of that sea is 334 feet beneath the level of the Mediterranean, 320 feet below the level of the Black Sea, and that of Lake Aral 203 feet ; the latter, as appears from the recent measurement of Captains Duha- mel and Anjou, being 117 feet above the level of the Caspian.* 71. As there is abundant evidence that those parts of the earth constituting the present continents and islands have been at some period or other covered by water, so it may be concluded that much of the bed of the sea was once dry land ; and indeed large tracts have been submerged with.in the period of historical record. M. De la Beche remarks, that "dry land can only be considered as so much of the rough surface of our globe as may happen, for the time, to be above the level of the waters, beneath which it may again disappear, as it has done at previous different periods."f General View of the Present State of the Surface of the Earth. 72. The exterior of the earth not only exhibits numerous varia- tions of level, but it likewise shows a diversity of structure and composition. Independent of the superficial covering formed from the mixture of decayed animal and vegetable bodies with sand, clay, and other materials, arising from the disintegration of stones and rocks, and serving as a nidus for the production and support of a continual ^succession of plants of every kind, from mosses, fungi, and grasses, to the noblest trees of the forest, there are many peculiar stratified or massive formations,^: sometimes extending What curious fact did Parrot and Engelhart discover respecting the in- land seas of Asia ? How are we to regard the dry land of the globe ? Of what is the exterior crust of the earth composed What is meant by the term formation ? (Note.) * Humboldt Fragmens de Geologic et Climatologie Asiatiques, torn. i. pp. 9. 91. 136. t Geolog. Manual, p. 2. t " In geognosy the \vordformation either denotes the manner in which a rock has been produced, or it designates an assemblage of mineral masses so intimately connected, that it is supposed they were formed at the same epoch, and that they present in the most distant parts of the earth the same general relations, both of composition and of situation with respect to each other. Thus the formation of obsidian and basalt is attributed to subter- ranean fires; and it is also said that the formation of transition clay-slate contains Lydian stone, chiastolite, ampelite, arid alternating beds of black limestone and of porphyry. The first acceptation of the word is the most conformable to the genius of the French language ; but it relates to the MODIFYING ACTION OF EXISTING CAUSES. 323 over vast tracts of country, and sometimes interrupted, mixed, and modified, producing new combinations, and by their various arrangements composing the solid crust of the earth, commonly more or less covered and concealed by vegetable mould and verdure, but occasionally by barren sands or clay, or appearing in the form of rugged, naked, or snow-clad rocks and mountains. 73. These formations, consisting respectively of series of rocks in a certain order of superposition, have been arranged by geolo- gists in groups, distinguished with reference to the supposed time or mode of their production : thus some are designated as primary, secondary, and tertiary; and some as sedimentary or volcanic. From examination of the surface of the earth, it appears that the strata or masses of rocks composing formations and groups have suffered numerous dislocations and interruptions, indicating local and general disturbances, the investigation of the nature and causes of which may advantageously precede more full and particular descriptions of the several groups, formations, and rocks, of which the crust or exterior portion of the terrestrial globe is composed. 74. Whatever may have been the cause of the original forma- tion of the oldest rocks, whether with the Wernerians we ascribe them to aqueous solution and crystallization, or with the Hutto- nians to igneous fusion, their production necessarily infers a con- currence of circumstances no longer existing. The case is different with respect to the superior strata composed of the ruins of the older rocks, and which, from their containing imbedded both animal and vegetable remains, must obviously have been formed at periods subsequent to the origin of organized beings. There- fore as the structure and arrangement of such rocks may be sup- posed to have been influenced by causes having some analogy with the existing order of things, an inquiry into the nature and extent of the changes now going on upon the earth's surface may be expected to throw some light on the geognostic history of those formations which took place long before the human species was called into existence. What is signified by a group in Geology? What different names are given to the respective groups of formations ? What changes have been produced in the different formations ? How do the superior strata of the earth differ from the inferior ? origin of things, and to an uncertain science founded on geogonic hypo- theses. The second acceptation, now generally received by the French mineralogists, has been borrowed from the celebrated school of Werner, and indicates, not what was supposed to have been, but what now exists. In the geognostic description of the globe, we may distinguish different modes of grouping mineral substances as we ascend to more general ideas. Rocks which alternate with each other, which are found usually together, and which display the same relations of position, constitute the same for- mation the union of several formations constitutes a geological series or group, (terrain ;) but the terms rocks, formations, and terrains, are used as synonymous in many works on geognosy." HumboldCs Geognostical Essay on the Superposition of Rocks, translated from the French. 1823. page. 1. 324 GEOLOGY. Influence of Mr, Water, and Volcanic Fire, on the Surface of the Earth. 75. Many of the changes that are affected on the superficial portion of the globe, are either directly or indirectly owing to the operations of man : the cutting down of woods and forests, drain- ing lakes and marshes, recovering tracts of land by embankment from the sea, levelling, mining, digging canals, constructing roads and causeways, with various other works that result from human skill and industry, contribute more or less to produce al- terations 011 the face of the earth ; but their agency is either remote and contingent, or comparatively insignificant, and therefore need not be particularly investigated. It is of more importance to consider the influence of the elements displayed on a far more extensive scale with regard either to time or space, and pro- ducing correspondent effects. 76. Air, water, heat, and perhaps electricity, sometimes acting slowly and gradually through long periods, may modify or change the form and constitution of substances composing the solid crust of the earth ; and on other occasions display overpowering force and violence, giving rise to storms and hurricanes, tides, currents, torrents, and deluges, earthquakes and volcanos, spreading deso- lation and ruin over wide tracts of land, breaking up and displac- ing existing strata, or covering them with beds of new matter, re- placing valleys by mountains, or mountains by valleys, and thus producing strange metamorphoses in the appearance of those countries over which their influence extends. 77. These powers of nature, however, are not solely active in works of destruction, their agency sometimes being productive of new formations. Air and heat may occasionally operate in this way, but the formative effects of water are more obvious and ex- tensive. Rivers deposit sands, detrital matter, and silt, filling up lakes, and constituting deltas on the margin of the sea, or shoals, sandbanks, and islands rising amidst its waves; lapidescent springs yield deposits of siliceous earth, tufa, travertin, and stalactitic limestone; and the water of the sea in some manner facilitates the operations of the little animals employed in build- ing coral reefs and islands. 78. The influence of the atmosphere in modifying the surface of the earth, whether destructive or formative, may depend either on the chemical or the mechanical properties of the aerial fluids of which it is composed. Air must be a powerful chemical agent, in consequence of its containing oxygen and carbonic acid. The action Of what importance are the labours of man, considered as modifying the surface of the globe ? What are some of the active causes which change the exterior condition of the earth ? What is among the most efficient of these causes ? To what properties does the air owe its modifying influence on the crust of the earth ? EVOLUTIOX OF CARBONIC ACID. 325 of oxygen may cause the disintegration of rocks in which metals and metallic sulphurets are included ; and, by its universal affi- nity for other bodies, it may give rise to numerous decompositions and combinations, the modifying effects of which must be alike extensive and important. 79. Carbonic acid, which is constantly present in the atmos- phere in a relatively small proportion, occurs abundantly in cer- tain situations, being given off from the surface of springs, or issuing from fissures in the earth. It is chiefly evolved in coal-pits and in volcanic districts. Among the most noted natural labora- tories of carbonic acid, is the Grotto del Cane, near Naples, the phe- nomena of which have often been described : and many others occur in different parts of the world. This gas is disengaged in vast quantities from every part of the Limagne d'Auvergne, in France, where it appears to have been produced in equal abundance from time immemorial. This elastic fluid being invisible, it is only observed in consequence of its effects, as when an excavation is made, in which it accumulates, and a lighted candle or other burning body introduced into it becomes extinguished. There are some springs in this district, where the water is seen bubbling and boiling from the copious disengagement of this gas. It has an obvious effect on the vegetation, many trees, as the walnut, flourishing more luxuriantly than they would otherwise do in the same soil and climate, probably owing to the rapid absorption or decomposition of carbonic acid. This gas is found in springs issuing from granite, near Clermont, as well as from the tertiary limestones of the Limagne.* 80. In the environs of Pont-Gibaud, not far from Clermont, a rock belonging to the gneiss formation, in which there are lead mines, has been found quite saturated with carbonic acid, which is continually given off in the gaseous form. The carbonates of iron, lime, and manganese, are so dissolved, that the rock is rendered soft, and the quartz alone remains unattacked.f Dolomieu notices the frequent evolution of carbonic acid in the vicinity of Mount Etna, and especially near Paterno. " An immense quantity is disen- gaged from the surface of a cold spring called Jlcqua Rossa, to the water of which it communicates a powerfully acid taste, and gives it the appearance of ebullition. This gas seems to be pure carbonic acid, proving suddenly fatal to animals that respire it, many being tempted by the freshness and limpidity of the water, shaded by bushes and reeds, to quench their thirst. Hares and How is the importance of carbonic acid proved ? In what particular localities does it abound ? What effect does it produce on the appearance of springs? What description has been given of the Acqua Rossa ? *Le Coq Annales de 1'Auvergne, torn. i. p. 217. May, 1828. t Lyell's Prin. of Geol., vol. i. p. 317, from Ann. d'Auvergne. June, 1829. See also G. Poulett Scrope's Memoir on the Geology of Central France. 2 E 328 GEOLOGY. birds are often found dead on the banks of this spring."* Similar effects are stated by MM. Bischof and Noggerath to be produced by the exhalation of carbonic acid from the vicinity of the lake of Laach, the quantity of which has been estimated at 600,000 pounds a day. 81. In the Brohlthal, on the Rhine, an old volcanic country, there is a considerable evolution of carbonic acid gas, which is employed by M. Bischof in the manufacture of chemical pre- parations on a large scale. f Near Fort Diadine, on the Eu- phrates, in Armenia, are mineral springs, impregnated with car- bonic acid and sulphuretted hydrogen, two of which are remark- able for the deposition of large quantities of carbonate of lime. In the environs of these two springs the limestone contains much native sulphur, which for a long time was collected ; but, the carbonic acid arising having suffocated many of the workmen, the undertaking was abandoned. The acid gas issues in this place from the bowels of the earth in such great quantities, as to fill the caverns and neglected excavations, forming numerous strata of livid vapours. It is sometimes evolved with so much rapidity through the clefts as to produce a strong current and a hissing noise. Small birds seeking refuge in these caverns, or coming near the fissures, are suddenly stifled.^: 82. But perhaps the most extraordinary phenomenon of this kind in the world is the Guevo Upas, or Valley of Poison, in the Island of Java, the deadly effects of which contributed in no small degree to give currency to the fabulous report of the existence of a wonderful tree called the Bohun Upas, so fancifully described by Dr. Darwin, in his " Botanic Garden." The district in which this valley is situated was visited by Mr. A. Loudon, who states that it is three miles from Balor, on the road to the Djung. He des- cribes it as about half a mile in circumference, of an oval form, from 30 to 35 feet in depth, and quite flat at the bottom ; destitute of vegetation, being covered with skeletons of human beings, tigers, hogs, deer, peacocks, and various sorts of birds, which have perished by entering into the atmosphere of carbonic acid, with which the lower part of the valley is filled. There were no visible openings in the ground at the bottom, which appeared to be of a hard sandy substance. The sides of the valley are covered with trees and shrubs ; and it may be concluded that the gas does not rise above 18 feet from the bottom, as Mr. L. and others with him What practical use is sometimes made of carbonic acid naturally de- veloped ? Describe the Valley of Poison. How high does the carbonic acid of that valley probably rise ? * Memoirs sur les Isles Ponces ; et Catalogue Raisonnee de Produits de 1'Etna. Paris, 1788. p. 364. f De la Beche's Geol. Man., pp. 154, 155. t Boue Memoires Geologiques et Paleontologiques. 1832. torn. i. p. 281. DISINTEGRATION OF GRANITE. 327 descended to that depth, where they experienced no difficulty of breathing or inconvenience, except that which arose from the offensive odour of the putrifying bodies below.* No smell of sulphur, or traces of volcanic matter were observed ; but there can be no doubt but the production of carbonic acid in this situa- tion is connected with volcanic influence, which extends through- out Java, and many of the neighbouring islands. S3. The effect of carbonic acid, as a chemical agent, both as commonly present in atmospheric air, and as more abundantly occurring in such localities as those above described, must de- pend on the nature of the rocks and other bodies with which it may come into contact. It may thus cause the decomposition of granite, gneiss, and other feldspathic and micaceous substances, by combining with the potash, soda, or lithia, which enter into their constitution. On the contrary, when it encounters lime or magnesia, it may contribute to the production of new rocks. "The disintegration of granite is a striking feature of large dis- tricts in Auvergne, especially in the neighbourhood of Clermont. This decay was called by Dolomieu, 'la maladie du granite; 1 and the rock may with propriety be said to have the ro/, for it crumbles to pieces in the hand. The phenomenon may without doubt be ascribed to the continual disengagement of carbonic acid gas from numerous fissures."! 84. The chemical action of carbonic acid, as it exists in the usual state of the atmosphere near the earth's surface, though much more gradual, and therefore less noticed than were it copiously evolved from the water or soil, as in volcanic countries, is yet sufficiently powerful to produce a manifest effect on the structure of large masses of granite and rocks of analogous com- position. In the western parts of Great Britain where primitive formations prevail, granite masses not unfrequently occur, which from their peculiar forms received the Celtocymric appellations of logan, tolmen, and kistvaens ; and were by Dr. Borlace and other antiquaries long regarded as works of art of Druidical origin ; but these rocking-stones, rock-basins, cheese-rings, and altars, are now generally admitted to be blocks of granite, which have acquired leir respective forms in consequence of superficial decomposition or disintegration. The manner in which this takes place may be illustrated by the following figure of a group of such decaying rocks, forming a part of Great Staple Tor, on Dartmoor, in Devon- shire, seen from the south-west, j: On what sources does the large supply of this gas depend ? To what cause may the disintegration of granite be ascribed ? What is the probable origin of rocking-stones and other detached masses of granite I * Journal of Geographical Society, vol. ii. t Lyell's Prin. of Geol. r vol. i. p. 317. t From De la Beche's Geological Researches. 328 GEOLOGY. 85. M. De la Beche remarks, that it is " more like the remains of some huge building or battlement, than the effect of cleavage and decomposition, which it is." Granite is not generally regarded as a stratified rock like gneiss and mica slate ; but it is a fact well known to the workmen who are employed in quarrying and cut- ting it, that it has what they term a grain, or that it will split in one or two directions more easily than in others.* This, doubt- less, is owing to the arrangement of the mineral bodies of which it is composed, and especially the feldspar, the decomposition of which must essentially aid the process of disintegration, and de- termine in a great degree the direction in which it takes place. 86. There are other gases which are copiously evolved in some .situations, and particularly in the vicinity of volcanos. Dolomieu states, that he ascertained the presence of sulphurous acid, mu- riatic acid, hepatic gas or sulphuretted hydrogen, phlogisticated or nitrogen gas, and inflammable air or hydrogen, as well as car- bonic acid, in the exhalations from the surface around Mount Etna ;f and other observers have noticed the occurrence of chlorine gas. But the most abundant of the spontaneously produced gases, next to carbonic acid, probably is carburetted hydrogen, well known as an agent of destruction in coal-mines. It is likewise some- times emitted from the surface of the soil, or of springs and wells. 87. The country around Baku, on the western shore of the Caspian Sea, is remarkable for its numerous mud volcanos and fountains of naphtha, the soil apparently being every where im- pregnated with bituminous matter. About ten miles to the north- east of Baku are many old temples of the Guebres, or fire- worshippers, in each of which there is a jet of inflammable gas issuing from apertures in the earth. Within an area of two miles in circumference, if holes be made in the earth, gas immediately rises, and may be set on fire by a lighted torch. The inhabitants What is the appearance of Great Staple Tor ? What character does granite manifest when we attempt to divide it me- chanically ? What gases are evolved from volcanos ? Which two of these are most abundant ? What peculiar appearance has been observed west of the Caspian Sea ? * Dr. Boase, who, from analogy of structure between granitic and schis- tose rocks, infers their common origin, has adduced sufficient evidence of an approach to stratification in the former. See his Treatise on Primary Geology. 1834. ch. vi. t Memoire surles Isles Ponces, &c., pp. 360 363. EVOLUTION OF GASES FROM THE EARTH. 329 fix hollow canes in such holes, and light the stream of gas from the top, availing themselves of the light and heat for domestic purposes. The flame is easily extinguished by plugging up the orifice of the tube. Besides the sacred and domestic fires, there is a large one which springs from a natural cliff in an open situa- tion, and which burns continually. 88. Mr. Kinneir states, that the whole country round Baku has at times the appearance of being enveloped in flames. " It often seems," he says, " as if the fire rolled down from the mountains in large masses, and with incredible velocity ; and during the clear moonshine nights of November and December, a bright blue light is observed at times to cover the whole western range. This fire does not consume, and if a person finds himself in the middle of it no warmth is felt."* 89. Captain Beaufort describes an ignited jet of inflammable gas, called the Yanar, near Delictash, on the coast of Karamania, anciently perhaps the object of religious veneration. He states, that "in the inner corner of a ruined building, the wall is so un- dermined as to leave an aperture of about three feet in diameter, and shaped like the mouth of an oven : from this the flame issues, giving out an intense heat, yet producing no smoke on the wall." Though the wall was scarcely discoloured, a little caked soot appeared in the neck of the aperture. The hill is composed of crumbly serpentine, and loose rocks of limestone. At a short distance down the hill there is another aperture, which, from its appearance, may have given out gas. The Yanar is supposed to be of ancient date, Pliny having described a similar phenomenon, probably with reference to this spot.f Such jets of inflammable gas have been observed in a mountain in the island of Samos, in a temple at Chittagong in Bengal, and near salt springs in China. 90. Both in Europe and America the spontaneous production of carburetted hydrogen has been taken advantage of for econo- mical purposes. In the salt mine of Gottesgabe, at Reine, in the county of Tecklenberg, there is an opening called the Pit of the Wind, from which a continuous current of this gas has issued for sixty years. M. Roeders, inspector of the mines, has, for a few years past, employed this natural gaslight for the purposes of illumination and for cookery.^: 91. Near the village of Fredonia, New York, are a number of what are called burning springs ; and gas issues from them, which x To what useful purpose is it applied ? What peculiarity belongs to the Baku gas fires? What is the situation and appearance of" the Yanar ? * See Hanway's Travels in Persia, vol. i. ; Geo. Forster's Travels over land to India; Macdonald Kinneir's Geographical Memoir on Persia; Engelhard t and Parrot's Travels in the Crimea and Caucasus in 1815, vol. '. ; and Humboldt Fragmens Asiatiques. t Karamania, or. Brief Description of the Coast of Asia Minor. 1817. jf Edinb. Journal of Science, No. xv. p. 183. 2E2 330 GEOLOGY. is collected in a gasometer, and conveyed by pipes to the village, which is thus lighted. The same kind of gas is evolved more copiously in the bed of a stream about a mile from the village. It consists of carburetted hydrogen, supposed to be derived from beds of bituminous coal.* A current of gas resembling this last was discovered in 1828, in the bed of a rivulet which crosses the north road between Edinburgh and Glasgow, about seven miles from the latter city. It is said to be emitted for more than half a mile along the banks of the rivulet ; and in one place, where many jets issued within a yard square, it was set on fire, and burnt uninterruptedly during five weeks, giving the clay soil the appearance of powdered brick. f 92. The extrication of inflammable gases from the bowels of the earth is interesting, as tending to illustrate the peculiar geo- logical structure of various distant portions of the earth's surface; and the gases issuing from volcanic districts must have some in- fluence on the nature of the minerals occurring in such situations ; but the quantities in which they are thus produced are relatively insignificant, and their formative or destructive effects must take place to an extent far inferior to those occasioned by oxygen and carbonic acid. 93. Gases are not the only kinds of foreign matter contained in the atmosphere, which forms a receptacle for all such bodies, whether fluid or solid, as are at any time exposed to its action, and are rendered capable of elevation by their inferiority of spe- cific gravity. Water, however, appears to be the only kind of matter which occurs in sufficient quantities in the atmosphere, to produce any considerable effect on the surface of the earth in con- sequence of its chemical properties. From its solvent power it must materially aid the operation of carbonic acid in the decom- position of rocks, and that property alone, as it is widely dis- persed, and in some places in great abundance in the lower strata of the air, renders it a formidable agent of destruction. 94. It has sometimes been supposed that the atmosphere ab- stracts water from the sea, holding in solution muriatic acid or salts. But from the experiments of M. Roubaudi at Nice, on the coast of the Mediterranean, it appears that when the sea is calm, the air on the sea-shore and over the sea, contains neither muriatic acid nor muriates, though when the sea is rough, and particularly if the wind is high, particles of sea-water, in a state of great tenuity, float in the air, but the distance to which they may be What use is made of the carburetted hydrogen from natural sources ? What is the probable influence of inflammable gases, compared with that of oxygen and hydrogen ? What is the relative influence of moisture on the texture of the earth's surface ? What is the condition in regard to freshness or saltness of water evapo- rated from the ocean ? * Edinb. Journ. of Science, No. xy. p. 183. t Edinb. Journal of Science, No. i., N. S. pp. 71 75. SHOWER OF VOLCANIC DUST. 331 carried inland, will necessarily depend on the force and direction of the wind.* 95. The action of the atmosphere on the superficial strata of the earth varies according to the circumstances under which it takes place. When it is in a state of repose its effects must prin- cipally depend on its properties as a chemical agent ; and these have been already noticed. Air, when in a state of agitation, as during the prevalence of winds, storms, tempests, hurricanes, and tornados, becomes a mechanical agent of vast power ; but its in- fluence is so generally blended with that of aqueous showers and currents, that it is difficult to ascertain the exact extent to which it operates ; and as the subject of aerial oscillations and disturb- ances belongs to meteorology, a few observations only will be requisite here relative to the effect of commotions in the atmos- phere on the surface of the earth. 96. Even when the air is perfectly still, the power of gravita- tion necessarily causes the ascent of all loose bodies from the earth, which are inferior in specific gravity to the lower aerial strata, and extremely minute particles of heavier matters are also elevated, probably from the action of temperature, producing mode- rately ascending currents. It is in consequence of their wonderful tenuity, that the seeds of cryptogamous plants, as mosses, fungi, and lichens, are often transported to great distances through the air, and thus such plants are found vegetating in situations in which it would be impossible otherwise to account for their exist- ence. " The sporules of fungi," observes Fries, " are so infinite, that in a single individual of Reticularia maxima, I have counted above ten millions, and so subtle as to be scarcely visible, often resembling thin smoke, so light that they may be raised, perhaps, by evaporation into the atmosphere, and dispersed in so many ways by the attraction of the sun, by insects, wind, elasticity, adhesion, &c., that it is difficult to conceive a place from which they may be excluded."! 97. To what great distances heavy substances in a state of minute division may be conveyed through the air, will appear from the following observations, made at Barbados, during a volcanic erup- tion in the island of St. Vincent's, which is about seventy miles directly westward from it: "In the night preceding the 1st of May, 1812, the inhabitants of the garrison of Barbados were alarmed by the noise of explosions from the westward, which seemed to proceed from fleets engaged at sea in that direction. At two pr three in the morning there was a strange sort of dust drop- On what two principles does the modifying action of the air depend ? How is the ascent of bodies in the air to be accounted for ? What evidence have we of the transportation of vegetable and other substances through the air ? What striking examples can be cited of the transportation of heavy materials through the air? * Journal de Pharmacie. 1833. t Lindley's Introduction to the Natural System of Botany. 332 GEOLOGY. ping from the air, which increased as the morning advanced. When daylight appeared, a large body of vapour appeared to the northward of the east, slowly advancing over the island, pro- ducing, in a manner sufficiently obvious, a darkness in the quarter from which it came, carrying before it a bright portion of the sky, bounded by an apparently circular line of dimensions successively diminishing until entirely shut in, and complete darkness covered all things. The ordinary darkness of night, always illuminated more or less by starlight, was not to be compared to this. It was total and absolute. The eye could not see the hand. It was an Egyptian darkness that might be felt. The dust continued to in- crease, and fell in such large quantities, as to cover every thing to the depth of more than an inch, and even to break down the branches of trees by lying on them. Between twelve and one o'clock in the day, a vertical shadowy light began to appear, the passage of light from the atmosphere above being shortest in that direction through the dust, in a circular form, which, as the dust thinned away or drove on, increased in diameter, until the whole body of particles passed away visibly. 98. By the impalpable particles of dust thus deposited, for many days men and animals were grievously annoyed ; even the tender leaves of plants were injured, and the wind agitating the dust, the whole face of the country showed like the crater of a volcano. The volcano of St. Vincents had burst out. The dust, thrown by explosions to considerable heights, had, by the higher currents of air, been carried to windward during the night, and, descending into the lower regions of the atmosphere, was driven back over the island by the ordinary tradewind a little to the north of east. During the fall, patterings on the roofs of houses, as of grosser particles than dust, were repeatedly heard, and some of the dust sent to me contained particles of stones, whose dimensions seemed to exceed all the power of floatage, so gross, that I was led to conceive that they were carelessly taken up from the soil on which the dust lay. Other portions of the dust were free from these. An analysis of this dust, in the laboratory of the Royal institution, by Mr. Faraday, gives the following components : silex 78, alumine 11.2, lime 7, oxide of iron .3.4, loss .4 = 100.* 99. " This floatage power of small bodies may account for the dust said to be observed on the tops of the highest mountains, to which the finest particles of smoke, and of whatever solid materials may be adequately divided, so as to be elevated and dispersed in Desenhe the phenomena accompanying the eruption at St. Vincents? How is the particular current of the shower of dust in that case to be ac- counted for ? What effect did it produce on the roofs of buildings? What was found to be the composition of the material then collected ? How is the dust on the surface of high mountains to be accounted for? * The small amount of loss, about l-200th of the whole, may probably have been owing to the -escape of hygroraetric moisture- INUNDATIONS OF SAND. 333 air, may rise, and in a given state of rest in the air above, unknown below, may quietly be deposited, and undisturbedly repose."* 100. During an eruption from the volcanic mountain of Tomboro, in the island of Sumbawa, in 1815, which will be subsequently noticed, the fall of dust and ashes was so great at Bima, forty miles eastward of the volcano, as to break down the roofs of the residency and other houses ; and on the side of Java, the volcanic powder was carried 300 miles, and more than 200 towards Celebes, in sufficient quantity to darken the air. 101. The influence of the atmosphere in modifying the surface of the earth must obviously be greatly augmented during the prevalence of high winds. Thus are formed dunes and sand-hills, which sometimes overwhelm cultivated fields, and the habitations of man, transforming fertile plains into barren trackless wastes. Such phenomena have taken place in the south of France, in Egypt, and in different parts of Scotland. 102. Cuvier remarks, that where the sand thrown up by the sea is left loose, it advances as irresistibly over the land as the silt and other alluvial matter carried down by rivers does over the bed of the sea. In their progress the sands push before them large pools formed by rain, intercepting their communication with the sea. On the coast of the Bay of Biscay they have overwhelmed many villages mentioned in records of the middle ages ; and in the department of the Landes alone, ten are now threatened" with destruction. Mimisan, one of these villages, has for twenty years been struggling against them, while a sand-hill more than sixty feet in height is approaching it. Their progress has been estimated at sixty feet annually, and in some places at seventy-two feet. According to this calculation they might in two thousand years reach Bourdeaux ; and, from their present extent, it must have been about four thousand years since they began to be formed.| 103. The sands of the Libyan deserts, driven by the west winds, have covered all the land formerly capable of tillage on the western bank of the Nile. Denon, in his " Travels in Lower and Upper Egypt," says that the summits of the ruins of ancient cities buried under these sands still appear externally. 104. In Morayshire, N. B., westward from the mouth of the river Findhorn, a district consisting of more than ten square miles of land, once termed, from its fertility, the Granary of Moray, has been depopulated and ruined by a sand-flood. The eruption com- menced about 1677, and its progress was gradual ; but in 1697 not What evidence of extensive motion in masses of dust is found in the East Indies? On what causes ie the formation of sand-hills supposed to depend ? What operation ie effected by the wind on sands upon the sea-coast? What examples of this are found in Europe? in Egypt? * On the Floatage of Small Heavy Bodies in Air, by G. W. Jordan, F R S., Journ. of Science, vol. viii, pp, 251 253. ^ Cuvier's Theory of the Earth, pp, 133135, 334 GEOLOGY. a vestige was to be seen of the manor-house, orchards, and offices of Coubine, two-thirds of the barony so called having been destroyed, and the sand was daily gaining ground. This sand came from Mavieston, on the coast, seven miles west from the mouth of the Findhorn, where from time immemorial there have been large accumulations of sand. It appears, however, that the catastrophe of Coubine "was occasioned by the bad practice of pulling bent and juniper," which occasioned an act of the Scottish Parliament, dated July 16, 1695, for the preservation of lands ad- jacent to sand-hills. The cause thus assigned as the origin of the devastation of Coubine, suggests an obvious remedy, in the plan- tation of vegetables which will grow in a sandy soil, such as the Jlrundo arenaria, and the Elymus arcnar'ius, the spreading fibrous roots of which give stability to the loose surface.* 105. Sands and fragments of sea-shells are sometimes raised from the beach to very considerable heights by violent winds, as is the case with the sands of Barry, at the north side of the estuary of the Tay, Scotland, where hills have been formed by them 140 feet high.f 106. Hurricanes, from their extraordinary force and violence productive of effects far beyond those of high winds, are generally accompanied by storms of rain, and the result of their influence, therefore, is partly owing to the impulse of gusts of air, and partly to that of floods of water. "They are of geological importance," says Mr. De la Beche, " as by the sudden application, if I may so express myself, of a furious wind and deluges of rain to the surface of land, very considerable changes are in a short time produced on that surface. "+ The velocity of the wind in hurricanes has been estimated at from eighty to one hundred miles an hour. 107. The hurricanes that occasionally ravage the Antilles, the Isles of France and Bourbon, Siam, China, Japan, and other countries between and near the tropics, overthrow solid edifices, uproot the strongest trees, involve animals and the produce of the fields in one common ruin, and sweep to a distance vast masses of solid matter. The desolating power of hurricanes may be estimated from the ensuing account of one which visited Guadeloupe, July 25, 1825. Houses firmly built were overturned ; and a new structure, erected at the expense of the government, in a most substantial manner, was ruined. The force and rapidity of the wind was such as to drive tiles through the thick doors of warehouses. A deal plank, about 39 inches long, 9^. inches wide, and T 9 ^ of an inch thick, was carried with such extraordinary velocity through the How is the motion of sand-hills to be prevented ? Of what importance are hurricanes in a geological point of view ? How is this proved ? Describe the effects observed in the tornado of Guadaloupe? * See Illustrations of Cuvier's Theory of the Earth, by Prof. Jameson. Note G. t I/yell's Princip. of Geol., vol, i. p. 313. J Geolog. Man., p. 149. DESTRUCTION OF ROCKS BY MOISTURE. 335 air, that it passed directly through the trunk of a palm-tree 17 T 7 T inches in diameter. A piece of wood 7.J inches square, and from 4 to 5 yards in length, was driven by the wind through the sur- face of a hard, beaten, and frequented road, to the depth of about a yard. A fine iron railing before the government house was entirely broken. Three pieces of cannon, twenty-four pounders, were dismounted, and driven against the breastwork of the battery in which they were placed. The accuracy of this statement was verified by inquisition on the spot, by General Baudrand, of the French engineers.* 108. The effect of air in modifying the surface of the earth, where it acts independently, is chiefly the result of its chemical properties : water is perhaps the most efficient as a mechanical agent. The influence of water, like that of air, is apparent both as a destructive and as a formative or constructive power ; dis- solving or wearing away solid surfaces in one situation, and depositing beds of transported matter in another. Indeed these operations must almost always be simultaneous or successive, the detritus of rocks and of organic bodies, removed by the agency of water from the higher parts of a country, serving to form new tracts of land, by filling up lakes, or composing deltas, sandbanks, or islands encroaching on the sea. 109. Mr. De la Beche, after describing the manner in which the disintegration of rocks may take place, owing to the protracted action of atmospheric moisture, and the more rapid and violent operation of streams and torrents in the degradation of land, says, " This destruction of the surface is common to most countries ; and if a rock so weathered be limestone, there is not unfrequently a reconsolidation of the parts by means of calcareous matter deposited by the water that percolates through the fragments, and which dissolves a portion of them. At Nice, the fractured surface In what manner does air produce the changes on the earth's surface ? How are the destructive processes of air and of water sometimes coun- terbalanced ? * Pouillet Elem. de Phys. Exper. et de Meteorol., torn. ii. pp. 717,718. A most destructive tornado passed over the city of New Brunswick, on the 19th of June, 1835. It was preceded by a sultry day, with a very high dew point, and was attended with some lightning ; but the thunder, if any, was drowned in the roar of the tornado. Rafters, 20 feet long and 8 or 9 inches wide by 3 inches thick, were carried half a mile ; a lad, nine years old, was carried one quarter of a mile through the air; more than 100 buildings were either demolished, unroofed, or otherwise injured. The track was but a few hundred yards in breadth ; and the editor of this work, with other gentlemen, who visited the spot on the day following, observed that trees, grass, buildings, &c. on the margin of the track, had been uniformly inclined inward toward the central line of the path ; a barn on one margin and a large store-house on the other, were raised each from its foundation and transported bodily some feet towards that line. In the forest the trees fell inward at the margin, and. gradually inclined more and more towards the point to which the storm was moving, as they were nearer the centre. Ed. 336 GEOLOGY. thus reunited is so hard, that if it occur on a line of road it must be blasted by gunpowder for removal. There are some fine ex- amples of this reconsilidation upon the limestone hills of Jamaica ; as, for example, near Rock Fort, and at the cliffs to the eastward of the Milk River's mouth. 110. "The feldspar contained in granite is often easily decom- posed, and when this is effected, the surface frequently presents a quartzose gravel. D'Aubuisson mentions, that in a hollow way, which had been only six years blasted through granite, the rock was entirely decomposed to the depth of three inches. He also states, that the granite country of Auvergne, the Vivarais, and the eastern Pyrenees, is frequently so much decomposed, that the traveller may imagine himself on large tracts of gravel.* " Some trap-rocks, from the presence of the same mineral, are so liable to decomposition, that there is frequently much difficulty in obtaining a specimen. The depth to which some rocks of this nature are disintegrated in Jamaica is often very considerable."! 111. The powerful effect of the continued action of running water on compact rock appears from the manner in which the river Simeto, in Sicily, has cut through a bed of lava. At the western base of Etna a great current of lava descending from near the sum- mit of the principal volcano, flowed over the alluvial plains of Simeto, the largest of the Sicilian rivers, which skirts the base of the mountain, and falls into the sea a few miles south of Catania. The lava entered the river about three miles above the town of Aderno, and not only filled its channel for some distance, but flowing to the opposite side of the valley, accumulated there in a rocky mass. The eruption is supposed to have taken place in 1603, and the appearance of the current proves that it is of modern date, for it has not been crossed or covered by any other stream of volcanic matter. In the course, therefore, of about two cen- turies, the Simeto has eroded a passage from fifty to several hun- dred feet wide, and in some parts from forty to fifty feet deep. The mass of lava cut through is not porous or scoriaceous, but a compact, homogeneous, hard blue rock ; and the general declivity of the bed of the river in this place is not very considerable.^: 112. A more striking example of the detrition of solid rocks by flowing water is exhibited at the falls of Niagara. At these falls " the water is divided by a small-island, which separates the river into two cataracts, one of which is six hundred yards, and the other three hundred and fifty yards wide : the height of the fall is What remarkable instances of the effect of exposing rock surface to the air have been observed ? What striking instances can be cited in which the erosive action of watejr has taken place ? * Traite de Geognosie ; ou, Expose des Connaissances actuelles sur la Constitution Physique et Minerale du Globe Terrestre, torn. i. t Geolog. Man. p. 45. J Lyell's Principle* of Geology, vol. i. pp. 258260. EFFECTS OF LAND FLOODS. 337 from one hundred and forty to one hundred and sixty feet. It is estimated that 670,000 tons of water are dashed every minute with inconceivable force against the bottom, and wearing down the adjacent rocks. Since the banks of the cataract were inhabited by Europeans, they have observed that it is progressively shorten- ing the distance of the falls from Lake Erie. When it has worn down the intervening calcareous rocks, the upper lake will become dry land, and form an extensive plain or valley, surrounded by rising ground, and watered by a river or smaller lake, which will occupy the lowest part. In this plain future geologists may trace successive strata of fresh-water formation, covering the subjacent ancient limestone. The gradual deposition of minute earthy particles, or the more rapid subsidence of mud from sudden inundations, will form distinct beds, in which will be found the remains of fresh-water fish, vegetables, and quadrupeds." 113. " Prof. Joseph Henry, in a topographical sketch of the state of New York,* says, * The descent of the country from Lake Erie to Ontario, is principally by a step, not at the falls, but at Lewis Town, several miles below. In viewing the position of the falls, and the features of the country round, it is impossible not to be impressed with the idea, that this great natural race-way has been formed by the continued action of the irresistible current of the Niagara, and that the falls, beginning at Lewis Town, have, in the course of ages, worn lack the rocky strata to their present site. The deep chasm through which the Niagara passes, be- low the falls, is nearly a rnile wide, with almost perfect mutual sides. 114. The bed of the river below the falls is strewed with huge fragments of rocks, hurled down by the cataract. The retrogres- sion of the waterfall, owing to the destruction of the surface over which it takes its course, is said to have amounted to nearly fifty yards during the last forty years. If the excavation always pro- ceeded at the same rate, it must have required about ten thousand years for the formation of the whole ravine f and it would take up more than thirty thousand years from the present time before the channel would be worn backward to Lake Erie, a distance of twenty-five miles. 115. The power of running water in removing stones and heavy materials, and changing the face of a country, was remarkably exemplified in the effects of the great flood which happened in August, 1829, in the province of Moray, and adjoining districts, in Scotland. The storm which occurred on this occasion displayed all the characteristic violence of a tropical hurricane. The inun- What change is now taking place on therock at Niagara Falls What is the nature of the channel of the Niagara? At what point did the fall first exist ? What known changes have taken place in the position of those Falls? * Transactions of the Albany Institute, vol. i. 2F 338 GEOLOGY. dating rivers were the Nairne, the Findhorn, and the Spey, with their numerous tributaries. All the low intervening- lands were covered, and the bridges and buildings along the banks were in general swept away. The plain of Torres was inundated to an extent of twenty square miles, and the destruction every where great. On the Nairne a fragment of sandstone rock, fourteen feet long, three feet wide, and one thick, was carried more than two hun- dred yards down the river. Some new ravines were scooped out on tho sides of the mountains, where no streams had previously flowed, and ancient river channels, which had never been filled from time immemorial, gave passage to copious floods. 116. Sir Thomas Dick Lander, who published a narrative of this occurrence, has given the following animated description of the devastation which took place in his own ornamented domain : " We were roused while at dinner by the account the servants gave us of the swollen state of the rivers ; and in defiance of the weather, the whole party sallied forth. We took our way through the garden, towards the favourite Mill Island. The magnificent trees on that island were overthrown faster and faster, offering no more resistance to their triumphant enemy than reeds before the mower's scythe. Each one as it fell gave one enormous splash on the surface, then a plunge ; the root appeared above water for a moment; and then uprose the stem, disbranched and peeled; after which, they either rolled round in the caldron, or darted like arrows down the. stream. Besides the loss of the Mill Island, which I had looked for, the beautiful hanging bank, covered with majestic forest and ornamental trees of all kinds, and of growth so fresh and vigorous, had vanished like the scenery of a dream ; and in its place was the garden hedge, running for between two and three hundred yards along the brink of a red alluvial perpendicular precipice, fifty feet high, with the broad, remorseless flood rolling at its base, eating into its foundation, and every successive minute bringing down masses of many cubic yards. And then, from time to time, some tall and* graceful tree, on the brink of the fractured portions of the bank at either end, would slowly and magnificently bend its head, and launch into the foaming waves below. The whole scene had an air of unreality about it that bewildered the senses. It was like some of those wild melodramatic exhibitions, where nature's operations are out-heroded by the mechanist of a theatre, and where mountains are thrown down by artificial storms."* 117. A bridge of granite over the Dee, at Ballatu, consisting of five arches, with a water-way of 260 feet, which had stood firm for twenty years, was destroyed and swept away by the torrent, 4p What remarkable effect of floods has been witnessed in Scotland ? What account has Lauder given of that occurrence ? * An Account of the Great Floods of August, 1829, in the Province of Moray, by Sir T. D. Lauder, Bart., 1830. CHANGES EFFECTED BY RUNNING WATER. 339 the whole mass of the masonry having 1 disappeared in the bed of the river. " The river D6n," says Mr. Farquharson, in his account of this catastrophe, " has, upon my own premises, forced a mass of four or five hundred tons of stones, many of them two or three hundred pounds weight, up an inclined plane, rising- six feet in eight or ten yards, and left them in a rectangular heap, about three feet deep, on a flat ground; the heap ends abruptly at its lower extremity."* 118. Animals, as well as trees and the produce of the fields, were involved in the general ruin caused by the flood, the effects of which at the mouth of the river Spey are thus described : " For several miles along the beach, crowds were employed in endea- vouring to save the wood and other wreck with which the heavy rolling tide was loaded ; whilst the margin of the sea was strewed with the carcasses of domestic animals, and with millions of dead hares and rabbits. Thousands of living frogs also, swept from the fields, no one can say how far off, were observed leaping among the wreck."f 119. It has been remarked, that the transporting effect of water is vastly augmented by the relative diminution of specific gravity in bodies more or less immersed in that fluid ;:J: and when ice adheres to detached rocks, the joint masses become really lighter than the stony substances would be separately. Hence we may in some measure account for the distribution of large blocks of franite over the surface of several parts of Europe, at great istances from, the primitive rocks whence they appear to have been derived. 120. The phenomena caused by floods, debacles, and torrents, manifesting the sudden effect of powerful impetus, imposing as they are, cannot have contributed so extensively to the production of the changes apparent on the surface of the earth, as the slow but indefinitely protracted operation of running water more or less loaded with silt and sand, and conveying it from higher to lower levels, to extend the limits of old continents, or form the founda- tions of new ones. Professor Robinson, in an article on " Rivers," in the Encyclopaedia Britannica, has furnished some estimates of the effects of flowing water, whence it appears that a velocity of three inches per second at the bottom will just begin to act upon fine clay in a firm state, and tear it up : a velocity of six inches What evidence is afforded, by the flood of 1829, that rocks and boulders may ^n other parts of the earih'have been dislodged and worn by water ? What effect had that flood upon animals ? In what manner may blocks of granite have been transported from place to place on or near the surface of water ? By what means, besides by floods and torrents, does water operate to change the surface of the earth ? * Account of the Flood, by the Rev. James Farquharson, in Quarterly Journal of Science, New Series, No. xii. p. 331. t Sir T. D. Lauder's Account, p. 312. t See Scientific Class Book, part i. pp. 130 and 160. 340 GEOLOGY, will lift fine sand, that of eight inches will raise sand as coarse as linseed, twelve inches will sweep away fine gravel, twenty-four inches will roll along rounded pebbles an inch in diameter; and it requires a velocity of three feet per second to sweep along shivery angular stones of the size of an egg. 121. Whatever matters may be taken up by flowing water will be again deposited as soon as the velocity of the stream becomes inferior to that which caused their removal ; so that only the finer particles of detritus will in general be carried into the sea. The distance to which river-water, loaded with such particles, would flow over sea-water, must deppnd on a variety of obvious circum- stances. Captain Sabine found discoloured water, supposed to be that of the Amazons, 300 miles distant in the ocean from the em- bouchure of that river. It was about 126 feet deep. Its specific gravity was = 1.020J, and the specific gravity of the sea-water = 1.02G2. This appears to be the greatest distance from land at which river-water has been detected on the surface of the ocean.* 122. The quantity of detrital matter conveyed by the rivers to the sea must be greatly influenced by the nature of the countries through which they take their course. The Hoang-ho, or \ ellow river of China, flows through alluvial tracts, and the quantities of mud and earth carried down by its current gives the water the appearance of diluted clay. According to Mr. Barrow, it pours into the sea every hour 2000 feet of solid earth, sufficient in seventy days, if accumulated on one spot, to form an island a mile in circumference ; and it has been observed, that a sensible di- minution takes place in the depth of the Yellow sea, into which the turbid river discharges itself. The addition of lands that have been made in the Netherlands, along the shores of the North sea; in Italy, on the borders of the Adriatic;! and in Egypt, at the mouth of the Nile ; together with many other phenomena of a similar nature have been noticed by historians and geologists.^: 123. The alluvial matter conveyed to the sea by great rivers may not only produce deltas or additions of land to the coast, but also give rise to insular formations. This has taken place at the mouth of the Ganges, which during the flood season pours into the gulf such a quantity of mud and sand, that the sea only recovers its transparency at the distance of sixty miles from the shore. Hence an island has arisen opposite the mouth of the Hoogly Mention the velocities which have been found adequate to wear away the bottoms of rivers of different materials? How does it appear that the features of a country may be changed by alluvial deposits ? * De la Beche's Geol. Researches, p. 72, t According to Strabo, Ravenna, in the time of Augustus, stood among lagunes, as Venice does now, and at present the former city is a league distant from the shore. t See Cuvier's Theory of the Earth, pp. 123132. Also Transactions of the British Association at Ediaburg, in 1834. FORMATION OF VALLIES. 341 river, (one of the branches of the Ganges,) and immediately south of Saugur island, four miles from the nearest land of the delta. It is said to have been discovered in 1816, together with the canal dividing- it from Saugur. It is situated 21 35' N. latitude, and 88 20' E. longitude, from Greenwich ; its position agreeing with that assigned to the bank of Saugur. A lighthouse has been erected on this spot, which is named Edmonston island. For many years it has been covered with shrubs and herbage ; but the whole surface was inundated for some hours during the flood in May, 1833, the light-keepers having escaped destruction by as- cending into the lantern. Its dimensions before that time were stated to be two miles from east to west, and half a mile from north to south ; but it was reduced in size by the inundation, and must have since been enlarged."* 124. Dr. Hutton ascribed the formation of valleys on the surface of the earth to the erosive action of rivers, as a general cause ;f and though the more extensive observations of subsequent in- quirers render his conclusions questionable, there can be no doubt but in some situations valleys may be thus produced. The ef- fect of flowing water must depend on its rapidity and consequent impetus ; and hence compact rocks occasionally have their surfaces ploughed with gullies and hollows by the power of mountain streams Dr. Bigelow, in describing the White mountains of New Hampshire, says: " In several places a broad continued stripe de- scended the mountains, having the appearance of a regular road cut through the trees and rocks from near the base to the summit. On examining these with a telescope, they were found to be channels of streams, and in several places the water could be seen dashing down the rocks. 125. " In a plain near the base of the mountains was a pond of one or two acres, situated near the road, and which having no other inlet or outlet, appeared to be the principal source of the Saco river. The waters of this stream, being collected from several sources, proceed directly towards the side of the moun- tain. At the point where, to all appearance, they must be inter- cepted in their course, there occurs one of the most extraordinary features of the place, well known by the name of * the Notch.' The whole mountain, which otherwise forms a continued range, is here cloven quite down to its base, affording a free opening to the waters of the Saco, which pass off with a gradual descent towards the sea. This gap is so narrow that space has with difficulty been obtained for the road, which follows the course of the Saco through the Notch to the eastward. In one place the How is this illustrated in China? in Hindostan? To what did Hutton attribute the formation of valleys? In what manner is the effect of water produced in mountain torrents? Describe the effect of torrents on the White mountains ? * Monthly Magazine Lyell's Prin. of Geol. vol. i. p. 354. t See De Luc's Elementary Treatise on Geology, translated from the French, by the Rev. H. De la Fite. 1809. p. 89. 2 F 2 342 GEOLOGY. river disappears, being lost in the caves and crevices of the rocks, and under the shelves of the adjoining precipice, reappearing at length at the distance of some rods below. The Notch gradually widens into a long narrow valley."* It appears that the upper part of the rock was gneiss and granite ; and near the Notch, chiefly course reddish jasper, and phorphyry.f 126. The manifest effect of lakes must, in general, be formative, rather than destructive, contributing to the production of new strata, by moderating the influence of running water, and furnish- ing cavities for the deposit of detrital matter. But the bursting of the banks by which lakes are restrained may occasion inun- dations and debacles, causing important modifications of the sur- face of a country. 127. Such would take place, as already remarked, if lake Erie was to have its outlet cut backwards to its border from the falls of Niagara ;:j: and if this work of ages were completed, the valley which now constitutes the basin of the lake would be traversed by a large river. The operations of nature, however, are gene- rally gradual ; and a concurrence of circumstances would be requisite to cause the sudden evacuation of the contents of a large lake. 128. A remarkable accident of this kind took place in 1818, in consequence of the bursting of a lake formed in the valley of Bagnes, in the Vallais. This valley, situated five leagues from St. Blanchier, is very narrow at one end, where a ravine is formed by mont Mauvoisin on the south side, and mont Pleureur on the north ; the latter, which is the highest, presenting a rocky sur- face above 500 feet in altitude, capped by the immense glacier of Chedroz. Large blocks of ice often falling from these heights accu- mulate continually in the valley, through which passes the river D ranee, fed by the waters of more distant glaciers. The stream had formed for itself a bed under the mass of ice and snow ; but in the winter of 1818, the glacier, which had been gradually in- creasing, dammed up entirely the passage by which the river made its exit. The waters were thus retained within the valley, forming an immense lake, confined on one side only by the wall of ice. On the 1 4th of May the lake was 7200 feet or a mile and one-third in length, and 630 feet in breadth, its greatest depth being 129. The government of the canton of Vallais, to prevent as far What kind of rock constitutes the upper part of the White mountain ? How may violent effects of water be seen to take place on the removal of its barriers ? What example of this kind happened in the valley of Bagnes? * Abstract of an Account, of the White Mountains. By Jacob Bigelow, M. D. Brande's Journal of Science, vol. ii. p. 393. t Idem, p. 397. \ In 1831, we happened to be present at the Falls of Niagara, and to witness the descent of a lars:e mass of rock from beneath the shelving cliff uader which visiters pass to arrive beneath the sheet of water. ED. $ Se.e De Ja Beche's Geolog. Man. pp. 59 61. LAKE OF NEUFCHATEL. 343 as possible the ravages to be apprehended from a sudden inunda- tion, had an artificial gallery 700 feet in length, cut through the ice, 50 feet below the level of the lake. This was completed in time to carry off a large portion of the water, reducing it from about 800,000,000 to 530,000,000 cubic feet. But on the approach of the hot season, the central part of the remaining wall of ice gave way, with a tremendous crash, and the lake was emptied in half an hour, the flood sweeping away trees houses, bridges, and large masses of rock, some of which were of enormous size. It desolated the plains of Martigny, and afterwards passed on with diminishing velocity till it entered the Rhone, on whose current the bodies of some men who had been drowned were carried a distance of about thirty miles, to the further side of the lake of Geneva, near Vevay. 129. In 1595, an inundation took place in the valley ofBagnes, owing to precisely the same cause with that of 1818, it destroyed the villages situated on the banks of the Drance, and carried away a great part of the town of Martigny.* 130. When deposits take place of sand and other substances, transported by rivers into the basins of lakes, the effects will be analogous to those before noticed, as resulting from depositions on the bed of the sea. Islands in general will first appear above the surface of the water, which uniting with each other, and then with the land constituting the banks of the lake, must at length produce a level tract, intersected by the stream to whose action it owed its origin. Such formations must in most instances be gra- dual and protracted ; but indications of their progress have fre- quently been observed. 131. De Saussure, in his "Travels among the Alps," mentions having obtained several very fine views of the lake of Neufchatel. " We were struck," says he, " upon first beholding it, with the great extent which it must formerly have had : for the spacious, marshy, and horizontal meadows by which it is bounded on the south west, have unquestionably been at some period covered by What effect resulted from the discharge of the water from that, valley ? What previous occurrence of the same kind is recorded as having hap- pened at the same place ? What is the natural effect of the flowing of streams into lakes or inland seas ? What observation did Saussure make on the extent of Neufchatel lake? * Brande's Journal of Science, vol. v. pp. 372 374 ; and Edinb. Philos. Journ., vol. i. p. 187, &c. Mr. Bakewell, in noticing the catastrophe of 1818, says: " From the quan- tity of mud and stones which the current bore along, it resembled a moving mass of stones and earth. An English gentleman, who was descending die valley at the time, observed his horse exhibit by his motions great tre- pidation, of which he could not discover the cause, until a loud rushing noise occasioned him to look back, when he beheld what appeared like a wall, filling up the bottom of the valley, and advancing rapidly towards him. He instantly alighted, and scrambled up the adjacent rocks, leaving his horse to his fate." Introd. to Geof., p. 508. 344 GEOLOGY. its waters. We shall have occasion to make the same remark with respect to the other bank of the lake."* The alluvial land here mentioned, according to De Luc, still increases, but now very slowly ; the first deposits, on the contrary, accumulated rapidly from the abundance of debris encountered by the waters originally, when likewise their courses were less tortuous than at present.f 132. The higher part of the lake of Como is nearly filled up by the detritus transported by the Adda and Mera.:f: The former has divided the lake into two ; the smaller portion (known by the name of lago di Mesola) being so shallow, from the united de- posit of the two rivers and some torrents, that aquatic plants grow through the water on the eastern part; while on the western, in which there is a greater depth, the process of filling up is hasten- ed by means of stones, detached in such numbers, in particular seasons of the year, from the heights on that side, that a passage in a boat beneath the cliffs becomes exceedingly hazardous. " 133. The accumulation of solid matter in the basins of lakes, and the gradual transformation of lakes into rivers, are well de- scribed by Professor Playfair, and exemplified in the progressive changes observable in the lakes of Westmoreland and C umber- land. j| But it is unnecessary to multiply instances of such pheno- mena, the nature of which may be sufficiently understood from the details already given. 134. The destructive effect of water in the degradation of the surface of the earth, is obvious in the occurrence of those phe- nomena called landslips. Accidents of this sort may be produced by the weight of quantities of water percolating through porous strata, and collecting in communicating cavities at various depths, in consequence of which thick masses of rock, may be disrupted by the force of hydrostatic pressure.^" Water also may find its way to beds of argillaceous or calcareous earth, between rocks composed of denser matter, highly inclined, and producing dis- integration of the connecting strata, the superincumbent masses may fall by their own weight. Circumstances of this kind have repeatedly occurred in different parts of the Alps. 135. In 1248, a portion of morit Grenier, south of Chamery, in What evidence does lake Como furnish of a change of extent from de- trition of river banks? Into what are lakes converted when their basins have become choked up with detritus and other alluvial matter? How are landslips produced ? In what manner may water assist in producing them ? * Voyages dans les Alpes, sect. 390. t Treatise on Geology, p. 160. t See Sections and Views illustrative of Geological Phenomena, by Mr. De la Beche, pi. 31. $ De la Beche's Geol. Man., p. 53. II See Illustrations of the Huttonian Theory of the Earth, Edinb. 1802, p. 357. 1T See Scientific Class Book, part i., p. 133. (Hydr. No. 32.) LANDSLIPS. 345 Savoy, fell, and buried five parishes, including the town and church of St. Andrew, the ruins covering the space of about nine square miles, called les Jlbymea de Myans ,- which, notwithstand- ing the lapse of so long a period, still exhibits a singular scene of desolation.* Pleurs, a considerable town in the Grisons, with the neighbouring village of Schelano, was thus destroyed, August 26, 1618. On that day an inhabitant entered the town, and told his neighbours that he had seen the mountains cleaving; but he was only laughed at for his information. However, in the even- ing, the town and all its inhabitants, except this person, were overwhelmed by the fall of a vast mass of rock from the south side of the mountain of Corto, which had been loosened by per- colated water. 136. A part of the mountain near Servoz, on the road to Cha- mouni, fell down in 1751. The descent of the mass did not take place in this case at once, as happened at mont Grenier ; for the mountain, consisting of a succession of beds of limestone resting on sandstone and extremely fragile schist, gave way by degrees. For many days a succession of reports, like those of cannon, announced the continual falling of the rocks, day and night; and the air was filled with vast volumes of black dust, extending twenty miles. The rocks still appear to be subject to the con- stant action of rain ; and in 1821 Mr. Bakewell noticed appearances indicating the probability of a renewal of the catastrophe of 1751. 137. Three villages, with the inhabitants, were entirely de- stroyed in 1772, when the mountain of Pitz fell, in the district of Treviso, in the Venetian territory.f The fall of the mountain called Rossberg or Ruffiberg, in Switzerland, took place Septem- ber 2, 1806. It is 5196 feet above the level of the sea, and is situated opposite to mont Righi. At five in the evening, the Knippenhuhl rock, which formed the summit of the mountain, was on a sudden detached from its station, carrying with it part of the mountain a few feet in thickness on the western side, and about 280 feet on the eastern side, which rolling into the valley that separates the lake of Zug from that of Lauwertz, overwhelmed the entire villages of Goldan, Rothen, Busingen, Huezloch, and three-fourths of that of Lauwertz. The fall of a portion of the mountain into the lake of Lauwertz, filled up about one-fourth part of it, and caused such an inundation as overthrew a number What appearance is now presented where the fall of mont Grenier took place ? What other similar occurrences have taken place among the Alps? How did the fall of Chamouni differ from others in the same region ? To what is the difference attributed ? What peculiar circumstances accompanied the fall of the Rossberg? * See BakewelFs Introduction to Geology, Silliman's edition, page 315, where the account of the fall of mont Grenier is illustrated by a cut, re- presenting the present state of the Abymes de Myans. t Malte Brun's Geography, vol. i, p. 435. 346 GEOLOGY. of houses, chapels, mills, and other buildings, on the southern shore of the lake. Enormous masses of rock are said to have been carried through the air to prodigious distances. The rocks in falling brought down great quantities of earth, together with large blocks of flint, which were thrown on the opposite bank of the lake, to the height of from 80 to 100 feet. 138. In the villages overwhelmed not an individual escaped de- struction ; and eight or nine hundred persons fell the victims of this disaster. The structure of the Rossberg sufficiently accounts for the occurrence, which General Pfiffer is reported to have predicted twenty years previously. Its upper part is composed of beds of a compound rock, formed from the debris of the Alps at an antecedent geological period; and these being porous, admitted the percolation of water arising from rain and melted ice and snow, which softening the clay between the more solid strata, inclined at an angle of about 45, a slide took place, and they were precipitated into the valley below.* 139. A large portion of mountain consisting of rocks and soil, covered with fir-trees, separated from the highest region of the Alps, on the 4th of April, 1818, near the village of Soncebos, in the valley of St. Imier, in Switzerland, and covered with its stu- pendous wreck more than three hundred paces of the great road to Brienne. A party of travellers witnessed this terrific catastro- phe who, had they been a few moments later, would have been its victims. f 140. Partial alterations of the surface of a country may be produced by deluges of mud, owing to the bursting of peat- mosses and bogs. In December, 1772, Solway moss having been filled with water during heavy rains, rose to an unusual height and then burst. A stream of black thick mud flowed over the plain, like a current of lava; overwhelming some cottages, and co- vering 400 acres of land ; but fortunately without occasioning the loss of human life. The highest parts of the original moss sub- sided about twenty-five feet, and the lowest part of the country submerged was full fifteen feet deep.:J: 141. A similar phenomenon occurred more recently on the con- fines of Yorkshire and Lancashire, England. On the 2d of Sep- tember, 1824, at Haworth, five miles south of Keighley, in the West Riding of the county of York, and on the borders of Lan- cashire, about six o'clock in the evening, a part of the highlands on the Stanbury moor opened into a chasm, and sunk to the depth of six yards, in some places exhibiting a ragged appearance, and How is that event to be explained ? By what other mode may the surface of a country be covered with earthy deposits ? Describe the occurrence at Solway moss ? At Haworth ? * Nicholson's Journal of Natural Philosophy, 8vo. vol. xv. pp. 150 152. t Brande's Journal of Science, vol. v. p. 377. J Lyell's Principles of Geology, vol. iii. p. 137. DESTRUCTIVE ACTION OF FROZEN WATER. 347 forming two principal cavities the one was about two hundred yards, and the other not less than six hundred yards in circumfe- rence. From these hollows issued two immense volumes of muddy water, which uniting at the distance of upwards of one hundred yards from their sources, constituted, for about two hours, an overwhelming flood from forty to fifty (sometimes seventy) yards in width, and seldom less than four yards in depth. This dark slimy mixture of mud and water followed the course of a rivulet, overflowing its banks for twenty or thirty yards on each side, and to the distance of seven or eight miles from the immediate erup- tion ; all this way there was deposited a black moorish substance, varying from eight to thirty-six inches in depth, and mixed occa- sionally with sand and rocky fragments, pieces of timber, and up- rooted trees, which had been borne along by the impetuous tor- rent. 142. This heavy and powerful stream broke down one solid stone bridge, made breaches in two others, clogged up and stop- ped several mills, laid flat and destroyed many fields of corn, and overthrew to the foundation several hedges and walls. In its course it entered the houses, floating "the furniture about to the astonishment and terror of the inhabitants. At the time of the erup- tion, the clouds were copper-coloured and lowering ; the atmosphere was strongly electric, and unusually close and sultry. There was at the same time loud and frequent thunder, with much zigzag lightning, peculiarly flaring and vivid. An hour before there was scarcely a breath of air stirring, but the wind quickly rose to a hurricane ; and after blowing hard from six to eight o'clock, sunk again into a profound calm, at which time the heavy rain, which had continued all the while, ceased, and, with the exception of a few floating clouds, the sky was very serene. Part of the torrent of mud passed into the river Aire, rendering its stream turbid at Leeds, and causing the destruction of great quantities offish. 143. A still later inundation, from the bursting of a peat-moss, happened in the county of Sligo, in Ireland. After a sudden thaw of snow, in January, 1831, the bog between Bloomfield and Gee- vah gave way, and a black deluge flowing in the direction of a smalt stream, swept along heath, timber, mud, and stones, and overflowed several meadows and tracts of arable land. Passing through a piece of bog, the flood traced a wide and deep ravine, and carried away completely two hundred yards of a solid road.* The sudden removal of large tracts of land on the banks of the Mississippi is an event of frequent occurrence. The many bends, " cut offs" and lagoons, in that region, are the consequences of this aqueous action. What other phenomena acccompanied the latter event? What example of the bursting of a bog has been observed in Ireland ? What remarkable action takes place along the line of the Mississippi ? * Lyell's Principles of Geology, u. a. 348 GEOLOGY. 144. The destructive action of water in consequence of its' congelation by cold, is sometimes exhibited on a very extensive scale. In cold climates, the disintegration of rocks is caused by the freezing of water, which having insinuated itself into crevices in its utmost state of condensation, afterwards expands in the act of forming ice. Loud reports, owing to the rifting of rocks from this cause, frequently attest the magnitude and violence of the effects produced ; and thus large masses of rock with superincum- bent glaciers are torn from the summits and sides of mountains, and fall in desolating avalanches into the vales below. When larg^e rivers are frozen and a sudden thaw comes on, great blocks of ice floating on the swollen current may be driven against its banks and cut away from them considerable portions, which fall- ing into the water may obstruct its passage and cause floods, or even alter the course of a stream. The destructive operations of icebergs, when drifted against maritime cliffs and precipices, may obviously be productive of considerable modifications of the coast of a country, causing the fall of vast masses of rock and soil, to be afterwards disintegrated and scattered by the waves of the sea. 145. The influence of waves, breakers, and ocean currents, both in the degradation of land and in the formation of new strata beneath the water, contributes, perhaps, more than any other cause, to the alterations that are taking place on the superfices of the* earth. Their destructive effect is more immediately obvious when they act on cliffs composed more or less of soft materials, and rising somewhat abruptly above the level of the sea ; and hence the configuration of coasts will greatly depend on the relative hardness of the rocks of which they are composed. Thus the waves sometimes form bays or inlets by washing away portions of land ; and where their action is resisted by more dense materials, they produce only a partial effect : yet the most solid rocks may in time give way, and the progress of destruction influence the formation of ocean caves, or produce detached masses rising from the bosom of the deep, and presenting a variety of fantastic forms. 146. Dr. Hibbert, enumerating the effects of the waves on the- coasts of the Shetland islands, says : "The most sublime scene is where a mural pile of porphyry, escaping the process of disintegra- tion that is devastating the coast, appears to have been left as a sort of rampart against the inroads of the ocean ; the Atlantic, when provoked by wintry gales, batters against it with all the force of real artillery, the waves having, in their repeated assaults, forced themselves an entrance. This breach, named the grind of the Navir, is widened every winter by the overwhelming surge How may we explain the falling of masses of rock from mountains in lime of severe frosts? How shall we account for the change in form of maritime cliffs? What is the most active cause of changes in the earth's surface ? On what does the configuration of coasts depend ? EFFECTS OF WAVES AND BREAKERS. 349 that, finding a passage through it, separates large stones from its sides, and forces them to a distance of no less than 180 feet. In two or three spots, the fragments that are detached are brought together in immense heaps, that appear as an accumulation of cubical masses, the product of some quarry."* 147. The same writer gives instances of the destruction of islands, " until at last they become mere clusters of rocks, the last shreds of masses once continuous." Such was the origin of the granitic rocks called the Drongs, between Papa Stour arid Hills- wick Ness : and of a singular cluster of rocks, of a similar nature, to the south of the latter island. 148. The power of the sea when agitated is especially remark- able in overturning and drifting vast blocks of solid rock. Steven- son states that at the depth of two hundred feet the action of the sea is sufficient to break rocks in pieces, and throw them upon the coasts in masses of various forms and dimensions. He ob- serves that "numerous proofs of the sea being disturbed to a considerable depth have occurred since the erection of the Bell Rock lighthouse, situated upon a sunken rock in the sea, twelve miles off Arbroath, in Forfarshire. Some driftstones of large dimensions, measuring upwards of thirty cubic feet, or more than two tons weight, have, during storms, been often thrown upon the rock from the deep water. These large boulderstones are so familiar to the lighthouse-keepers at this station, as to be by them termed travellers."* 149. The effects of the more protracted action of waves and breakers is abundantly remarkable on various parts of the shores of England, and in few situations more so than on those of Suffolk. The gradual destruction of the once extensive, flourishing, and populous city of Dunwich, has been noticed by several writers. " Gardner, in his history of the borough, published in 1754, shows, by reference to documents, beginning with Domesday Book, that the cliffs at Dunwich, Southwold, Eastern, and Pakefield, have been always subject to wear away. 150. " At Dunwich in particular, two tracts of land which had been taxed in the eleventh century, in the time of King Edward the Confessor, are mentioned in the Conqueror's survey, made but a few years afterwards, as having been devoured by the sea. The losses, at a subsequent period, of a monastery at another of several churches afterwards of the old port then of four hun- What instance of the action of waves on hard rocks has been particu- larly noticed ? What changes are sometimes known to take place in the appearance of islands ? What is meant by the term " travelling rocks ?" What event proving the gradual encroaching of the sea on the land is recorded ? * Description of the Shetland Islands, Edinb. 1822, p. 528. t See Memoirs of the Wernerian Society, vol. iii 2G 350 GEOLOGY. dred houses at once of the church of St. Leonard, the high road, town-hall, the gaol, and many other buildings, are mentioned, with the dates when they perished. It is stated that in the six- teenth century, not one quarter of the town was left standing; yet the inhabitants, retreating inland, the name was preserved, as has been the case with many other ports, when their ancient site has been blotted out. 151. " There is, however, a church of considerable antiquity still standing, the last of twelve mentioned in some records. In 1740, the laying open of the churchyard of St. Nicholas and St. Francis, in the sea cliffs, is well described by Gardner, with the coffins and skeletons exposed to view some lying on the beach, and rocked ' In cradle of the rude impetuous surge.' Of these cemeteries no remains can now be seen. Ray also says, 'That ancient writings make mention of a wood a mile and a half to the east of Dunwich, the site of which must at present be so far within the sea.'* This city, once so flourishing and populous, is now a small village, w r ith about twenty houses, and one hun- dred inhabitants. "f 152. The action of tides and currents must be taken into the ac- count, in estimating the influence of the sea in producing modifica- tions of the surface of the globe. Tides are chiefly felt on the coasts, and their effects must be in a great degree similar to those above described ; but the operation of currents may cause a variety of changes in the bed of the sea, in some places scooping out hol- lows, and in others heaping up wide tracts, or where from particular causes their direction has undergone alteration, sweeping away and dispersing the sand-beds produced by former currents. There are currents of various descriptions, the most important being those which appear to be permanent. Such are the Gulf stream, and other branches of the great equinoctial current; the Polar or Greenland current, flowing strongly through Hudson's bay and Davis's strait ; a current, which sets eastward into the Mediter- ranean sea; and another that flows out of the Baltic, into the Ger- man ocean. Besides these, there are a considerable number of periodical and temporary currents, the transporting power and effects of which must vary with circumstances. 153. Such are some of the more general and widely-operating causes of the modifications of the earth's surface, which have taken place within the period of historical record ; but there are others, which are rather of a local nature, though their effects may in some cases be very extensive, and are often extremely striking What has preserved the name of Dunwich since its site has been in- gulphed ? What, besides the force of the winds, is effective in causing maritime detrition ? * Consequences of the Deluge Physico-Theological Discourses, t Lyell's Principles of Geology, vol. i. pp. 403, 404. CALCAREOUS DEPOSITS FROM HOT SPRINGS. 351 and important. Among these are chemical deposits from fresh water, marine formations, either from chemical deposition or the work of coral polypes ; and volcanos and earthquakes. All these are highly interesting, and might furnish materials for several volumes ; but among the numerous topics that remain to be con- sidered, they can here only obtain a passing notice. 154. Some thermal springs contain siliceous earth, held in solution by their waters, and deposited on cooling. Such are the Geysers in Iceland, previously mentioned. Their deposits extend over an area of about half a mile in diameter ; and from the depth of a cleft near the Great Geyser, the siliceous matter appears to be more than twelve feet in thickness. The hot springs of Furnas, in the volcanic district of St. Michael, one of the Azores, deposit large quantities of clay and silex, enveloping grass, leaves, and other vegetable bodies. Dr. Webster found " branches of the ferns, which now flourish in the island, completely petrified, preserving the same appearance as when vegetating, excepting the colour, which is now ash-gray. Fragments of wood occur, more or less changed ; and one entire bed, from three to five feet in depth, is composed of the reeds so common in the island, completely mineralized, the centre of each joint being filled with delicate crys- tals of sulphur."* The deposits are both abundant and various, frequently forming horizontal strata. In the cavities of the de- posits occur siliceous stalactites often two inches long, and covered with small brilliant quartz crystals. Compact masses, broken from various causes and cemented again by siliceous matter, form brec- cia, the elevations of which, in some places, Dr. Webster estimates at more than thirty feet. 155. There are hot springs at Washita, in Arkansas territory, in a district exhibiting some traces of extinct volcanos, f which deposit a very copious sediment, consisting of silex, lime, and iron ; and the thermal springs of Pinnarkoon and Loorgootha, in the East Indies, contain silica and various salts of soda. 156. Travertin, or calcareous tufa, is another deposit from springs ; and though it is most common in limestone districts it is by no means confined to them, occurring indiscriminately in all rock formations. In Auvergne, in France, where the primary rocks are unusually destitute of limestone, springs abundantly charged with carbonate of lime rise up through the granite and gneiss. Again, in the valley of the Elsa, which skirts the Apennines in Italy, are innumerable springs, which have thrown down such What change in the structure of the earth's surface is effected by the agency of animals ? What change is produced by the action of hot springs? What examples illustrate this kind of action ? What is the chemical nature of travertin ? In what localities has it been deposited ? * Edinb. Philos. Journ.. vol. vi. t See Featherstonbaugh's Geological Report, pp. 63 to 69. 352 GEOLOGY. calcareous precipitates, that the whole ground in some parts of Tuscany is coated with travertin, and sounds hollow under foot. A most striking instance of the rapid deposit of carbonate of lime from thermal waters may be observed in the hill of San Vignone, near Radicofani, and a few hundred yards from the high road be- tween Sienna and Rome. A large mass of travertin descends the hill from the point whence the spring issues to the bank of the river Orcia, a distance of 250 feet, "forming a mass of varying thickness, but sometimes 200 feet in depth ; and on the other side of the hill a similar deposit extends about half a mile in parallel strata, one of which is 15 feet thick, and constitutes excellent building stone. Large masses of travertin have also been deposited, forming escarpments along the borders of the stream into which the waters of the Washita hot springs descend. 157. Thermal springs, which yield calcareous deposits, are found in several parts of Italy, as the famous baths of San Filippo, on a hill a few miles from that above mentioned ; the Bulicami, or hot baths, in the vicinity of Viterbo ; a thermal spring, lately dis- covered near Civita Vecchia, which forms alternate beds of a yel- lowish travertin, and a white granular rock, resembling statuary marble; the lake of Solfatara, in the Campagna, between Rome and Tivoli ; and calcareous formations are taking place in the waters of the river Velino, at Terni ; and in those of the Anio, which produces the travertin of Tivoli.* Calcareous deposits from springs have been noticed in Bohemia. Hungary, Mount Caucasus, Persia, and in various other parts of the world. Mr. Mantell mentions an incrusting or lapidescent spring, at Pounceford, in Sussex ;f and such occur in Gloucestershire, and in other districts of England, where there are formations of limestone. 158. Precipitates of carbonate of lime are produced from the waters of some lakes; but there are others which yield deposits of a different nature, though on a comparatively contracted scale. Bog-iron ore is sometimes found at the bottom of lakes and peat- mosses ; and its origin is somewhat problematical. "It has been suggested that iron, being soluble in acids, may be diffused through the whole mass of vegetables when they decay in a bog, and may, by its superior specific gravity, sink to the bottom, and be there precipitated so as to form bog-iron ore ; or where there is a sub- soil of sand or gravel, it may cement them into ironstone, or fer- ruginous conglomerate."^: 159. In salt lakes considerable depositions of salt (chloride of sodium) take place; and such collections of water being dried up or drained, the sides and bottoms of the basins are found incrusted How is the presence of iron ore in lakes to be accounted for? What causes the deposition of salt at the bottom of salt lakes ? * See Lyell's Prin. of Geol., vol. i. pp. 296310. t Geology of the South-East of England, 1833, p. 223. t Lyell's Prin. of Geol., vol. iii. p. 331. See Rev. Dr. Rennie's Essays on Peat, p. 347. MARINE FORMATIONS. 353 with salt, sometimes constituting beds alternating with beds of clay. In South Africa salt is obtained from such natural basins ; and bay salt is the product of salt-pans or basins formed by art. On the western side of the Rocky mountains, in about latitude 42, is a salt lake, around which a party recently found it took them forty days to travel. The salt is believed to be brought down by the waters from saliferous rock strata in the mountains above. 160. Carbonate of soda is precipitated in considerable quantities from the waters of a lake in Venezuela ;* and similar deposits occur in other places. Gypsum, or sulphate of lime, which forms one of the beds in the great Paris basin, and must therefore have been deposited most copiously at some distant period, now appears to be confined to a very few springs. Those at Baden, near Vienna, which supply the public bath, may be cited as examples. Some of them yield from 600 to 1000 cubic feet of water an hour, and throw down a fine powder, consisting of a mixture of sulphate of lime with sul- phur and muriate of lime, (chloride of calcium. )f 161. In the island of Trinidad there is an extensive pitch-lake, the surface of which in wet weather is sufficiently hard to sup- port heavy weights ; but during the heats it approaches to a state of fluidity. This phenomenon, together with the existence of springs of naphtha and asphaltum in different quarters of the globe, may serve in some measure to elucidate the origin of bituminous shales, which occur in the geological formations of different-ages. 162. The destructive influence of the waves of the sea is fre- quently exerted within the range of observation, so that we may in many cases be able to appreciate the effect produced with tolerable accuracy. But the formative or constructive operations of the ocean, which are carried on upon the most extensive scale, are in general entirely hidden from our view. We have abundant reason to believe that many of the strata which compose the crust of the terrestrial globe were formed by deposition from sea-water, and that analogous formations are now in progress; but with respect to the latter, we are obliged to speculate in the dark, those processes of nature in general taking place at unfathomable depths beneath the surface of the ocean. 163. " As dwellers on the land, we inhabit about a fourth part of the earth's surface ; and that portion is almost exclusively the What evidence have we that sulphate of lime has been copiously de- posited from an aqueous solution? What facts enable us to explain the existence of bitumen in connexion with rocky strata ? Why are we less familiar with the processes of accumulation than with those of detrition when effected by the ocean? * A curious account of the manner in which soda is collected from this lake by the Indians, written by M. Palacio Faxar, may be found in Brande's Journ. of Science, vol. i. p. 188, &c. t Lyell's Prin. of Geology, vol. i. p. 311 ; from Essai sur la Constitution Physique du Bassin de Vienne, par C. Prevost, p. 10. 2 o2 354 GEOLOGY. theatre of decay, and not of reproduction. We know, indeed, that new deposits are annually formed in seas and lakes, and that every year some new igneous rocks are produced in the bowels of the earth, but we cannot watch the progress of their formation ; and as they are only present to our minds by the aid of reflection, it requires an effort both of the reason and the imagination to ap- preciate duly their importance. It is therefore not surprising that we imperfectly estimate the result of operations invisible to us ; and that, when analogous results of some former epoch are pre- sented to our inspection, we cannot recognise the analogy. He who has observed the quarrying of a stone from a rock, and has seen it shipped for some distant port, and then endeavours to con- ceive what land of edifice will be raised by the materials, is in the same predicament as a geologist, who, while he is confined to the land, sees the decomposition of rocks, and the transportation of matter by rivers to the sea, and then endeavours to picture to himself the new strata which nature is building beneath the waters."* 164. The rocks formed under the surface of the sea originated either from mechanical deposition, or from chemical precipitation. Those of the former class are numerous, including most of the stratified rocks which inclose sea-shells, fragments of corals, and other exuviae or bones of marine animals. Among those of the latter class, some geologists have reckoned even granite, f the origin of which, as well as that of all other unstratified rocks has, however, been more generally ascribed to igneous fusion and con- solidation. Most of the calcareous rocks containing marine shells, must have been produced under the influence of chemical affinity ; and of this nature are the formations which are occasionally ob- served to take place on the sea-coasts. 165. Collections of perfect and broken sea-shells *and corals are sometimes consolidated by the precipitation of calcareous and ferruginous matter, constituting banks or beds of considerable ex- tent. Such masses containing shells occur on various parts of the shores of Great Britain. Similar conglomerates, including both shells and corals, are not uncommon around some of the islands in the West Indies. At Guadaloupe human bones have been found imbedded in a rock of this kind, whence were obtained two im- What cause prevents our verifying the conjectures which geologists have formed in regard to this subject? From how many sources have submarine rocks derived their origin ? In what situation have human bones been obtained in a fossilized state? * Lyell's Prin. of Geol. vol. i. pp. 117, 118. t "'The strata of granite," says De Luc. " evidently produced by che- mical deposition from a liquid, form, as I have said, the most ancient monu- ment of the action of physical causes on our globe." Element. Treat, on Geol., p. 49. This writer, however, doubtless imagined the primitive ocean (capable of holding in solution the substances which constitute granite) to have been a liquid of a different nature from the waters of the present ocean. CORAL ROCKS AND ISLANDS. 355 perfect human skeletons, one preserved at the British Museum, and the other in the Museum of Natural History, at Paris ; and from the occurrence of these bones and other circumstances, may be inferred the comparatively modern origin of the rock in question. The Florida Keys abound in deposits of shells in various states of disintegration and subsequent union by cement. 166. Among- the marine formations there are few more curious or interesting than coral reefs and islands, which to a certain ex- tent are constructed by different kinds of polypiferous zoophytes,* or minute animals, for which the coral tubes serve as habitations. It has been supposed that the coral rocks descend in perpendicular columns to the bed of the ocean, and cover millions of acres of the Pacific ;f but though the extent of such formations is very con- siderable, it appears to have been overrated. 167. M. Chamisso, who accompanied as a naturalist the expe- dition of discovery sent out by the Russian government, under the command of Captain Kotzebue, visited several groups of coral islands, arranged in a circular or oval form, with openings among them which afforded access to the interior basin. These islands seemed to be only the upper portions of ridges of unequal heights, on the inside of which, towards the basin or lagoon, where there is still water, the smaller and more delicate kinds of polypes carry on their operations, while the stronger species live and work on the exterior margin of the bank, against which a great surf usually breaks. 168. These creatures leave off building as soon as their struc- tures reach such a height as to be left almost dry at the lowest ebb of the tide. A continuous mass of solid stone is seen com- posed of shells of molluscs and echini, with their broken-off prickles and fragments of coral cemented by calcareous matter. The ridge is raised by fragments of corals thrown up by the waves, till it becomes so high as to be covered only by high tides and at certain seasons. Masses of the stone thus formed are sometimes separated and thrown upon the surface of the reef, so as gradually to augment its elevation. The calcareous sand on the top now furnishes a soil in which seeds of trees and plants brought by the * What is the nature of coral reefs? What conjectures have been formed respecting their extent ? What facts have been ascertained in regard to the different classes of animals which build the coral islands ? How high are they capable of rearing their structures? * "Of the numerous species of zoophytes which are engaged in the pro- duction of coral banks, some of the most common belong to the genera Mt-andrina., Con/ophillia, and Astrea, but especially the latter." LyelVs Prin. of Geol, vol. iii. p. 221. t "The reefs in the Pacific are sometimes of great extent: thus the in- habitants of Disappointment Islands, and those of Duff's Group, pay visits to each other by passing over long lines of reefs from island to island, a distance of six hundred miles and upwards. When on their route they present the appearance of troops marching upon the surface of the ocean." LyelVs Prin. of Geol., vol. iii. p. 235 ; from Malte-Brun's Geography. 356 GEOLOGY. waves vegetate rapidly, and overshadow its dazzling white sur- face. " Entire trunks of trees, which are carried by the rivers from other countries and islands, find here at length a resting- place after their long wanderings : with these come some small animals, such as lizards and insects, as the first inhabitants. Even before the trees form a wood, the sea-birds nestle here ; strayed land-birds take refuge in the bushes : and at a much later period, when the work has been long since completed, man appears, and builds his hut on the fruitful soil."* 169. MM. Quoy and Gaimard, who sailed in the French ex- pedition, more recently, under Captain Freycinet also examined with attention the coral rocks and islands ; and they were led to conclude that the polypi ferous zoophytes do not begin building from any considerable depths below the surface of the sea, but merely produce incrustations a few fathoms in thickness ; and that the appearance of these reefs and islands depends on the inequalities of the mineral masses beneath, the circular form of many of them indicating their foundation on the crests of sub-? marine craters. It is supposed that those species of animals, which chiefly contribute to the formation of coralline islands, do not live in water at the depth of more than 30 feet; though the branched corals have been brought up in sounding off Cape Horn, in about 50 fathoms water, and Reteporse have been found as low as 100 fathoms; but these do not form solid masses, though the ruins of their habitations might in time compose banks that would serve as platforms, which the other species might make the foundations of their more compact structures. 170. Observations were made, during a recent voyage of Captain Beechey to the Pacific, whence it may be inferred that the eleva- tion of coral rocks proceeds in general very slowly ; but a curious circumstance noticed by Mr. Lloyd, while engaged in his survey of the isthmus of Panama, shows that bodies cast on submarine banks, where the coral animals are at work, may be very speed- ily cemented to the surface, and a considerable increase of height may hence take place in a short time. This gentleman, " seeing some beautiful polypifers on the coast, detached speci- mens of them ; and it being inconvenient to take them away at the time, he placed them on some rocks or other corals, in a shel- tered and shallow pool of water. Returning to remove them a few days afterwards, it was found that they had secreted stony matter, and fixed themselves firmly to the bottom. Now this property must greatly assist in the formation of solid coral banks ; What is the progress of change from a coral reef to an inhabitable island ? At what depths and on what foundation has it been supposed that ihe coral animals commence their operations ? What peculiar power have those animals in regard to the connexion of their structures with other solid substances ? * Lyell's Prin. of Geol. vol. iii. pp. 221, 222; from Kotzebue's Voyage in 18151818, vol. iii. - EARTHQUAKES AND VOLCANOS. 357 for if pieces of live corals be struck off by the breakers, and thrown over into calm water or holes, they would affix themselves and add to the solidity of the mass."* 171. It has been the subject of curious speculation whence the coral polypifers and testaceous mollusca can obtain the vast quan- tities of carbonate of lime, which they secrete to form the enve- lopes by which they are protected. Mr. Bakewell considers it as more than probable that they have the extraordinary faculty of pro- ducing- lime from simple elements ;f and Dr. Macculloch seems disposed to impute its origin, in the same manner, to the influence of vital energy, in combining elementary bodies. If this were admitted, it would follow that the quantity of lime on the surface of the earth must be progressively increasing, unless it be sup- posed that other natural processes are regularly taking place for the decomposition of calcareous earth, or rather of its metallic basis, calcium. 172. Mr. Lyell, in opposition to this doctrine, says: "We see no reason for supposing that the lime now on the surface, or in the crust of the earth, may not, as well as the silex, alumine, or any other mineral substance, have existed before the first orga- nic beings were created, if it be assumed that the arrangement of the inorganic materials of our planet preceded in the order of time the introduction of the first organic inhabitants. " He adds, in reference to the abundance of carbonate of lime furnished by springs which rise through granite : 173. " But if the carbonate of lime secreted by the testacea and corals of the pacific, be chiefly derived from below, and if it be a very general effect of the action of subterranean heat to subtract calcareous matter from the inferior rocks, and to cause it to ascend to the surface, no argument can be derived in favour of the pro- gressive increase of limestone from the magnitude of coral reefs, or the greater proportion of calcareous strata in the more modern formations. A constant transfer of carbonate of lime from the in- ferior parts of the earth's crust to its surface, would cause through- out all future time, and for an indefinite succession of geological epochs, a preponderance of calcareous matter in the newer, as contrasted with the older formations."|j Earthquakes and Volcanos. 174. There are many circumstances which indicate such a con- nexion between earthquakes and volcanos, as may warrant the What different conjectures have been stated in regard to tbe source of the materials of which corals are composed ? How may the abundance of iime on or near the surface of the earth be explained ? * De la Beche's Geol. Man., p. 165. t See Introduction to Geology, Silliman's ed. p. 86. \ System of Geology, vol. i. p. 219. $ Principles of Geology, vol. iii. pp. 241, 242. || Principles of Geology, u. a, 358 GEOLOGY. conclusion that they depend on the same general cause. Both these phenomena are manifestly owing to the agency of subterranean heat. Volcanic eruptions of lava in a state of igneous fusion, of red-hot stones and ashes, and of columns of steam, afford suffi- cient evidence of the very high temperature that must subsist in the interior of the earth. The phenomena of earthquakes, also, which seem to be owing to the sudden expansion of gases, va- pours, and perhaps of solid matter, display equally characteristic effects of the influence of internal heat. 175. Earthquakes and volcanos frequently happen at the same time ; and, indeed, an eruption of lava from a burning mountain, even when comparatively inconsiderable, can hardly take place without some agitation of the surface of the surrounding country ; every volcanic paroxysm, therefore, is probably attended with an earthquake, and the extent of the commotion is usually propor- tioned to the violence of volcanic action. Those countries in which there are volcanos are more frequently visited by earth- quakes than such as are distant from them. But the latter are by no means exempt from such visitations. Indeed, there is perhaps no part of the earth's surface that may not be occasionally shaken, though there are many in which the experience of ages has led the inhabitants to regard such phenomena, so far as relates to themselves, rather as objects of curiosity than of alarm. 176. Next to those countries which are the seats of open or extinct volcanos, mountainous districts, and especially those con- sisting of primary rocks, are the most frequent scenes of earth- quakes ; though secondary and tertiary hills, wide level tracts, marshes but little above the sea, sandy deserts and fertile fields are more or less exposed to their destructive operation. They occur in all climates, cold, temperate, or tropical ; as is also the case with volcanos. Both kinds of phenomena appear to be more prevalent near the sea-coast than elsewhere ; thus Syria, the coasts and islands of Asia, America, the countries bordering on the Mediterranean, and Iceland, have been repeatedly devastated by them; while the plains of Asia, Africa, and the north of Eu- rope, experience comparative security. 177. The occurrence of earthquakes is by no means unfrequent. Mr. Lyell observes, that Von Hoff has published from time to time, in a German journal, lists of the earthquakes which have happened since 1821 ; and from these it appears that every month has been signalized by one or more convulsions in some part of the globe.* To what cause are earthquakes and volcanos to be referred? What pr"oof have we of the justness of that supposition? In what parts of the globe are earthquakes most frequently felt ? What, besides volcanic countries, are frequently visited by earthquakes 1 What relation appears to exist between inland and maritime districts in respect to the frequency of their occurrence ? What does observation prove in regard to the periods at which earth- quakes take place ? * Principles of Geology, vol. ii. p. 175. PHENOMENA OF EARTHQUAKES. 359 The recurrence of earthquakes, either where they are common, or where they are slight and unfrequent, has not been observed to take place at any particular periods, nor to be influenced by the seasons of the year, and they happen sometimes by day and sometimes at night, and in various states of the atmosphere.* 178. The principal phenomena of earthquakes consists of trem- blings and vibrations of the surface of the earth, extending to various distances, and often having a certain direction. These shocks begin in general with elevations of the ground, followed by horizontal undulations, and in some instances by violent irre- gular agitations, and by vortical or gyratory motions. To these may be added, the rending, slipping, rising, and sinking of the Boil and substrata ; the sudden retreat of trie sea, and its impe- tuous return, alternately laying bare the sands and beaches, and in its tremendous inroads on the shores sweeping away trees, buildings, and other solid masses ; the violent agitation of lakes, which sometimes sink into the earth; the drying up or bursting forth of springs and rivers ; and the occurrence of inundations, from the fall of fragments of rock or soil, which may block up their channels. 179. The distances to which the effects of earthquakes extend are very great. Thus when the terrible catastrophe of Lisbon happened in 1755, the shock was felt not only over nearly the whole of Europe, but also in the West Indies. The earthquake which visited the coast of Chili, November 19th, 1822, is said to have been felt simultaneously throughout a space of 1200 miles from north to south. And in the same year Aleppo, in Syria, was destroyed by an earthquake, the influence of which extended from the banks of the Euphrates to the island of Cy- prus, in the vicinity of which two rocks are stated to have risen from the sea. 180. The duration of shocks has been variously estimated, from a few seconds to more than two minutes. It is probable, however, What influence has season, weather or time of day upon their recurrence ? What are the kinds of motion felt during earthquakes? How extensive are their effects when most violent ? * " It has been considered that earthquakes are presaged by certain atmospheric appearances; but it may be questionable to what extent this supposition is correct. Historians of earthquakes seem to have been generally desirous of producing effect in their descriptions, adding all that CQuld tend to heighten the horror of the picture. They have not always, moreover, been anxious or able to separate accidental from essential circum- stances. As far as my own experience goes, which is, however, limited to four earthquakes, the atmosphere seemed little affected by the movement of the earth, though I should be far from denying that it may be so, for we can scarcely imagine such movements to arise in the earth without some modification or change of its usual state of electricity, which would affect the atmosphere. If animals be generally sensible of an approaching shock, (as has been asserted,) it might arise as well from electrical changes, as from the sounds which they may be supposed capable of distinguish- ing." De to Beches Geol. Man., pp. 140, 141. 360 GEOLOGY. that single agitations seldom last more than half a minute, and are often of shorter duration ; as may be concluded from the remarks of observers on those slighter shocks which occur in situations where the apprehension of danger is not likely to distract the attention. Though the shocks are sometimes single, yet it more frequently happens that they recur rapidly at various intervals ; and in volcanic districts especially, they have been repeated oc- casionally for months or years. The famous earthquake that desolated Calabria, in Italy, and extended across the strait to Messina, commenced in February, 1783, and the shocks continued till the close of 1786. 181. Among the phenomena caused by shocks, there are few more singular than those which result from the gyrations or rota- tory movements, which have been already noticed. During the earthquake of Catania, the general direction of which was from south-east to north-west, many statues were turned round on their pedestals, and a large mass of rock was turned 25 from the south towards the east. The same effect was more remarkably observa- ble during the earthquake at Valparaiso, N in November, 1822, when many houses are reported to have been turned round, and three palm trees were found twisted together like the strands of a rope. Earthquakes are almost always preceded by unusual agi- tations of the waters of the sea and of lakes ; and springs some- times send forth torrents of fetid, dark mud. A noise immediately precedes the shock, which has been described as resembling the dragging of loaded waggons rapidly over a rough pavement, an irregular but sudden discharge of batteries of cannon, or the rushing of a hurricane. 182. The phenomena of slight shocks are probably in general very similar to those which were noticed in England in 1797. A person who was in bed at Gloucester, about midnight, and hap- pened to be awake, observed an undulation of the surface of the ground, extending from south-west nearly to north-east, and the bedstead, which was placed in that direction, seemed to be slightly raised from foot to head, and sink again with a wave-like motion ; while the agitation was sufficient to cause the sashes of the win- dows to rattle, much in the same manner as they do in conse- quence of the passing of carriages through streets where the excavations for vaults and sewers extend beneath the surface ; and it was reported, that in some houses in Gloucester, plates, dishes, and other articles were thrown dow r n from the shelves on which they had stood. The whole lasted not more than a few seconds. 183. Before we proceed to consider the influence of earthquakes in modifying the surface of the earth, and the different opinions What is the ordinary duration of the motion produced by this occur- rence ? What singular movement in bodies produced by earthquakes has been observed to take place ? What indications of approaching earthquakes are afforded by the ocean? What kind of sounds are most frequently observed to attend their shock ? VOLCANOS. 361 that have been advanced as to the extent and importance of their effects, it will be requisite to take some notice of volcanos, with which they are so intimately connected. The general description of volcanos is that of openings in the crust of the earth, through which are ejected, from time to time, various gases, cinders, ashes, stones, and streams of lava, composed of red-hot melted rocks. From the accumulation of matters thus discharged, conical emi- nences are formed, with funnel-shaped cavities called craters ; and they generally occupy the summits of isolated peaks or mountains. 184. Volcanos occur in all quarters of the globe, and are often distributed in groups over wide areas ; as in the volcanic band which includes Sumatra, Java, the Moluccas, and the Philippine islands; and the line of the Andes in America, extending from Chili, or perhaps from Terra del Fuego, to Mexico. They are often found near the shores of continents, or in islands ; and hence it has been supposed that they have some necessary connexion with the sea. But recent researches have shown, that they also occur, though more rarely, at great distances from the ocean, or any considerable body of salt water. 185. Volcanic mountains differ greatly in height. That of Esk mount, in Jan Mayen's island, between 70 49' north latitude and 71 8', is but 1500 feet above the sea-beach, in Jameson's bay; Vesuvius is 3932 feet above the level of the sea; Hecla, in Ice- land, rises to the height of 5000 feet; and that of Etna, in Sicily, is 10,870 feet : but the loftiest mountains are those of the Andes ; as Pichincha, the height of which is about 15,931 feet; Coto- paxi has an elevation of 18,8G7 feet, and Antisana attains that of 19,136 feet. Volcanos occur in various latitudes, from Greenland and Kamtschatka to Sumatra and Columbia; nor is the sea by any means exempt from them, numerous islands having at diifof- ent periods been raised by volcanic action from the bed of the ocean in different parts of the world, some of which have remained permanently above the waves, though most of those whose origin has been noticed have subsequently sunk, forming only submarine reefs and sandbanks.* 186. The number of the volcanos now occasionally in activity has been stated by some to be about two hundred ; though, accord- ing to others, they amount to rather more than three hundred, in- cluding solfataras, or smoking volcanos. But besides those from, which eruptions have issued within the period to which our records extend, there are many extinct volcanos, of which abundant traces remain in several countries. Thus in France, the territories of What is meant by the term volcano ? How are volcanos distributed over the surface of the earth? At what different elevations do they occur? What number of active \olcanos has been ascertained to exist? * For an interesting account of a volcano in the island of Hawaii, (or Owhyhee,) the reader is referred to Silliman's Am. Journal of Science vol xx., p. 228; and vol. xxv., p. 199. ED. 2H 362 GEOLOGY. Auvergne, Vivarais, and the Cevennes, exhibit conical mountains, composed of lava, scoria?, and volcanic ashes ; and in some of them the forms of the craters may still be discovered. The dis- trict around the town of Olot, in Catalonia, and that of the Eifel and the Lower Rhine, in Germany, present similar appearances. 187. Some volcanos are perpetually active, as is the case with that of Stromboli, in the Mediterranean. It is mentioned by Pliny ; and there is reason to believe that its eruptions have been almost incessant during the last two thousand years. According- to Dolomieu, its crater does not exceed fifty paces in diameter. "I saw it dart," says that writer, " during the night, at regular intejr- vals 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 number fell into the crater, while others roll- ed even to the sea. Each explosion was accompanied with a burst of red flame." Mr. G. P. Scrope, from personal observation on this volcano, states, that " there evidently exists within and below the cone of Stromboli, amass of lava, of unknown dimensions, per- manently liquid, at an intense temperature, and continually tra- versed by successive volumes of aerifom fluids, which escape from its surface thus presenting exactly all the characters of a liquid in constant ebullition."* 188. Among those which may be styled intermitting volcanos, the most important are found amidst the Andes. Cotopaxi is the loftiest of these burning mountains, from which, at recent epochs, eruptions have proceeded. It is also the most dreadful of all those in Quito, and subject to the most frequent destructive explosions. The mass of scoriae, and the huge fragments of rocks thrown out of this volcano, cover a surface of several square leagues, and would form, were they heaped together, a colossal mountain. In 1758, the flames rose 2900 feet above the brink of the crater. In 1744, the roaring of the volcano was heard on the borders of the Magda- lena, a distance of about 200 leagues. On the 4th of April, 1768, the quantity of ashes ejected by the volcano was so great that the inhabitants of the towns of Hambato and Tacunga, were obliged to use lanterns to walk the streets at noon day. The explosion, which took place in January, 1803, was preceded by the sudden melting of the snows that covered the mountain. For twenty years before, no smoke or vapour had been observed to issue from the crater ; and in a single night, the subterraneous fire became so active that at sunrise the external walls of the cone were heated Where have extinct volcanos been observed ? What distinction has been founded on the periods of activity in vol- canos ? What example of constantly acting volcanos can be given ? Where are the most important intermitting volcanos found ? What remarkable events have been observed in the eruptions of Coto- paxi? * Considerations on Volcanos, by G. P. Scrope, F. R. S. ERUPTION OF TOMBORO. 363 to such a temperature as to appear quite naked, and of the dark colour characteristic of vitrified scoriae.* 189. One of the most dreadful volcanic er-uptions on record, is that which occured in the mountain of Tomboro, in the island of Sumbawa, eastward of Java, in April, 1815. It commenced on the 5th of April, was most violent on the llth and 12th, and did not cease entirely till July. Out of a population of twelve thousand persons only twenty-six escaped destruction. Violent whirlwinds swept away men, horses, cattle, and every thing which came within their vortex, tore up the largest trees, and covered the neigh- bouring sea with floating timber, f Large tracts of land were inun- dated by lava, several streams of which issuing from the crater, reached to the sea. Vast clouds of volcanic dust and ashes, as be- fore mentioned, were conveyed to immense distances, blackening the air, and for a time eclipsing the sun. The floating cinders to the westward of Sumatra, formed on the 12th of April a mass two feet in depth, and several miles in surface, through which ships with difficulty forced their way. 190. A captain of a ship, who was at Macassar on the llth of April, says : " By noon, the light that had remained in the eastern part of the horizon disappeared, and complete darkness had cover- ed the face of day: our decks were soon covered with falling mat- ter ; the awnings were spread, fore and aft, to prevent it as much as possible from getting below ; but it was so light and subtile, that it pervaded every part of the ship. The darkness was so pro- found through the remainder of the day, that I never saw any thing equal to it in the darkest night ; it was impossible to see your hand when held up close to the eye. The ashes continued to fall with- out intermission through the night. At six o'clock the next morn- ing, when the sun ought to have been seen, it still continued as dark as ever ; but at half past-seven I had the satisfation to per- ceive that the darkness evidently decreased, and by eight I could faintly discern objects on the deck. From this time it began to get lighter very fast, and by half-past nine the shore was distinguish- able ; the ashes falling in considerable quantities, though not so heavily as before." 191. " The appearance of the ship, when daylight returned, was most extraordinary ; the masts, rigging, deck, and every part being covered with the falling matter ; it had the appearance of calcined pumicestone, nearly the colour of wood ashes ; it lay in What meteorological occurrences attended the eruption of Tomboro ? What account has been given of the extent and depth of the darkness produced by the floating cinders ? * Edinburgh Review, vol. xxiv. p. 142 ; from Humboldt's Researches concerning America. t For a theory of tornados, referring them to a disturbance of atmospheric equilibrium by the condensation of vapour and the consequent heating of superior strata of air, causing strong ascending currents, see the subse- quent treatise on meteorology, ED. 364 GEOLOGY. heaps of a foot in depth in many parts of the deck, and I am con- vinced several tons weight were thrown overboard ; for although a "perfectly impalpable powder or dust when it fell, it was, when compressed, of considerable weight. A pint measure filled with it weighed 12| ounces ; it was perfectly tasteless, and did not effect the eyes with any painful sensation ; it had a faint, burning smell, but nothing like sulphur. By noon, on the 12th, the sun again appeared, but very faintly, through the dusky atmosphere, the air still being charged with the ashes, which continued to fall lightly all that day and the succeeding one." 19*2. Along the sea-coast of Sumbawa, and the neighbouring islands, the water rose suddenly from two to twelve feet, great waves rushing up the estuaries, and again retreating. At Bima, about 40 miles westward of the volcano, though the wind was still during the whole time of the eruption, the sea rolled in upon the shore and filled the lower parts of the houses with water a foot deep. Every prow and boat was driven from its anchorage, and thrown ashore. The perpendicular depth of the ashes that fell here was found to be 3| inches. The noise of the explosions, as heard from this place on the 14th, is said to have been most terrific, resem- bling the reports of a heavy mortar fired close to the ear. The town called Tomboro, on the western side of the volcano, was overflowed by the sea, which encroached upon the shore at the foot of the mountain, so as to leave the land permanently sub- merged to the depth of 18 feet.* 193. "The changes produced by such eruptions as that here recorded, would, independently of the alteration in the shape of the volcano itself, and of the streams of lava which flowed from it, extend to very considerable distances. On the dry land, vege- tables and animals would be entombed beneath stones and ashes, the, quantity of the covering matter probably increasing with the proximity of the volcano. And if it should chance, as sometimes happens, that the aqueous vapours discharged from the volcanic vent were suddenly condensed, f the torrents produced would sweep away not only the looser riarts of the volcano, but also the plants and animals which they might encounter, imbedding them in a thick mass of alluvial matter. The vegetable and animal substances enveloped by the discharged ashes, cinders, and stones, falling into the sea, would be both marine and terrestrial ; and a very curious mixture, so far as regarded its organic contents, would be observed : trees, men, cattle, fish, corals, and a great What sensible qualities were possessed by the cinders which fell on that occasion? How was the sea affected, and what evidence have we that it arose from other than the ordinary causes ? What important geological phenomena may result from such occurrences as at Tomboro ? * Brande's Journal of Science, vol. i.; Hist, of Java, by Sir T. S. Raffles vol. i. p. 28, &c. ; Life of Sir T. S. Raffles, t See note on preceding page. ED. SUBMARINE VOLCANOS. 365 variety of marine remains, would be incased, and it might so happen that, both on the land and in the sea, a bed of lava might cover such accumulations."* 194. The quantity of solid matter ejected from some volcanos is immensely great. Vesuvius, Etna, and other volcanic moun- tains have, at different times, discharged lava, cinders, and ashes, the total bulk of which would at least equal that of the mountains whence they issued. During one eruption of Etna, an area 150 miles in circumference is said to have been covered with a stratum of volcanic sand or ashes 12 feet deep. In 1775, the same xolcano, according to Dolomieu, poured out a stream of lava 12 miles in length, 1^ in breadth, and 200 feet in thickness. That writer also states, that some of the currents of lava from Etna are 10 leagues in length, and 3 in breadth. f But the most extensive known cur- rent of modern lava appears to be that formed by a volcano in Iceland, in 1783, which is 60 miles long, and 12 broad, equalling in extent any continuous rock formation in England.^: The surface of the country for many leagues round Naples seems to be com- posed of volcanic matter. Herculaneum and Pompeii, which were covered by vast showers of ashes during the first recorded eruption of Vesuvius, A. D. 79, when they were partially disinterred in the course of the last century, were ascertained to have been founded on a volcanic rock, and their streets were paved, and some of their buildings constructed of blocks of lava, of uncertain but early origin. 195. The present cone of Vesuvius is supposed to have been formed since the eruption just mentioned, and the more ancient lavas to have flowed from the adjacent mountain, now called Somma. Near Puzzuoli, on the coast of the bay of Baiae, a mountain was thrown up suddenly, September 29, 1538, after repeated shocks of earthquake. Its present height is 440 feet above the level of the sea; and it is about 1 miles in circum- ference. This volcanic cone is called monte Nuovo ; and at a short distance from it is another of more ancient date, and larger dimensions, named monte Barbaro. 196. The phenomena of submarine volcanos resemble, in many respects, those of sub-aerial volcanos ; the chief difference consist- ing in the more copious emission of aqueous vapour and gases, and in the formation of temporary or permanent islands. It is probable that Owhyhee, and many other islands in the Pacific, were formed in this manner; as also the Canary islands, the Azores, and several others. Such likewise was the origin of the What striking facts illustrate the force and duration of volcanic actions? What evidence have we that Herculaneum and Pompeii were not de- stroyed by the first eruption of Vesuvius? What extinct volcanos are found in Italy ? * De la Beche's Geol. Man. p. 132. t Memoir sur les Isles Ponces, &c. p. 166. J Bakewell's Introd- to Geol., p. 378. $ See the reference to Am. Journal of Science, on page 361. 2H2 366 GEOLOGY. Lipari islands, as wo learn from history; and of some of those in the Grecian archipelago, where a new island arose in 1707, called Nea [New] Kaimeni, near Santorin, which, as well as some of those adjacent, was thrown up at a more remote period.* Among the numerous instances on record of islands produced by subma- rine volcanos which have subsequently sunk beneath the surface of the water, one of the most recent occurrence was that, the elevation of which took place in July, 1831, between the island of Pantellaria and the coast of Sicily. This has been circumstan- cially described by different observers ; but for the highly inter- esting details we must refer to the annexed authorities.]" 197. Some volcanos eject only gases and vapours, and these are called solfataras, or, where the cones are very small, fumarole, and in Mexico, hornitos ; others send forth torrents of water and mud, as is the case with the volcano of Macalubba, in Sicily, and frequently with the volcanic peaks of the Andes ; but the more usual products of volcanic action are streams of lava, and showers of scoriae, sand, and ashes, accompanied, however, by clouds of steam and gas. As to the composition of lavas, exact information is wanting. However, Mr. Phillips says, " it is nearly certain that feldspar and augite are the principal ingredients, and 'that the colour of the lava is dependent on the prevalence of the one or the other. 198. "The minerals which are discoverable as entering, in notable proportion, into the composition of volcanic masses, are very few ; as feldspar, compact feldspar, augite, hornblende, oxidulous iron, olivine, mica, leucite ; other minerals, indeed, are found in their cavities, but these can scarcely be said to enter into the composition of the rock." " It is remarkable, that quartz, so extremely abundant in rocks of which the composition is not suspected to be of volcanic origin, is scarcely ever found in such as are decidedly volcanic."^: It must, however, be observed that Mr. Poulett Scrope enumerates among volcanic rocks, quartz- iferous trachyte, containing numerous crystals of quartz ; and siliceous trachyte, having much silex in its composition. 199. As to the causes of volcanos and earthquakes, various opinions have been proposed, some of which appear to be quite inconsistent with the effect produced. Thus Werner and his dis- In what particulars do submarine, differ from other volcanos ? What striking examples of this kind of volcanos are found in different parts of the globe ? To what is the term solfatara applied ? What mineral ingredients are most abundant in the matter ejected from volcanos ? * Lyell's Prin. of Geol., vol. ii. pp. 151155. t Philos. Transactions for 1833 ; Journal of Geographical Society, 1831 , Annales des Sciences Naturelles, torn. xxiv. ; and Lyell's Principles of Geology, vol. ii. pp. 145 150. t Outlines of Mineralogy and Geology, p. 264. $ Quarterly Journal of Science, vol. xxi. 1826 CAUSE OF EARTHQUAKES AND VOLCANOS. 367 oiples attributed them to the spontaneous combustion of beds of coal ; and others imputed their origin to the inflammation of vast repositories of sulphur or petroleum, collected in caverns of the earth ; and the experiment of Lemery, noticed elsewhere,* has been alleged as affording an explanation of the manner in which sulphur and iron might take fire when buried in the earth. A more plausible hypothesis was proposed by Sir H. Davy, who having discovered that potash and soda were the oxides of highly inflammable rnetals, which become oxidated wilh the extrication of abundance of heat when they come in contact with water, sought to explain volcanic phenomena, by imagining the existence of large quantities of the metallic bases of the alkalis within the bowels of the earth, and their sudden oxidation through the access of sea-water to the cavities in which they were contained. This theory has been adopted and advocated recently by Dr. Dau- beny, in his " Description of Active and Extinct Volcanos ;" but it seems inadequate to the full development of the agency on which the vast power and extensive influence of these phenomena de- pends. ... 200. Earthquakes and volcanos may be supposed to have a common origin, since volcanic eruptions are generally preceded by agitations of the surface of the earth, such as would necessa- rily be caused by the efforts of heated and expanded fluids, either liquid or gaseous, and especially of the latter, embowelled in the earth, to escape through the superincumbent strata. It is true, that earthquakes happen frequently in countries where there are now no volcanos, and it may be admitted, that they sometimes are neither accompanied nor followed by volcanic eruptions ; but this only proves, that the elastic force of expansive fluids confined within the earth, may not always be sufficiently powerful to over- come at once the resistance to their exit, and therefore they cause concussions of the surface ; and accordingly it has been ob- served, that repeated earthquakes during longer or shorter pe- riods have frequently preceded violent volcanic eruptions. 201. If, then, earthquakes and volcanos depend on the same causes, the source of these phenomena must be very deeply seated below the earth's surface : f>r though volcanos might be regard- ed as confined to certain localities, the action of earthquakes seems to be almost unlimited, since these concussions of the sur- face have been felt over nearly half the globe. Mr. Bake well, in reference to the earthquake of Lisbon, the shock of which was perceived in the United States and the West Indies, observes, that "the cause which could effect a simultaneous concussion over such a vast extent, must probably have been seated nearly What different theories have been adopted to account for volcanic phe- nomena ? What circumstances indicate that earthquakes and volcanos proceed from a common cause ? * See Treatise on Chemistry. 368 GEOLOGY. midway between the centre of the globe and its surface."* Such widely acting power cannot reasonably be ascribed to the topical agency of chemical affinities ; and hence some bold specu- lators have inferred, that these phenomena are connected with the central fire, or rather with the candescent matter supposed to exist in the interior of the earth. Volcanos, therefore, are considered as safety-valves, by means of which some portions of the sub- stances in fusion which form the internal mass, escape from time to time, with violence, to flow over the surface of the soil.f 202. The electric influence, whatever may be its nature, cannot but be considered as one of the most powerfully active causes of the changes which have at former periods been produced in the surface of the earth as well as of those which are now in progress. But notwithstanding the discoveries which have been recently made relative to electricity, and its connexion with magnetism, we are still too little acquainted with its mode of action to be enabled fully to appreciate the extent of its operations. 203. There can be no doubt but the chemical combinations and decompositions of bodies on the surface of the earth must be greatly influenced by atmospheric electricity ; and there is some reason for concluding that subterranean phenomena may depend on its mysterious agency. " Now the identity of magnetism and electricity seems, in many respects, to be established, it may de- serve consideration, whether an interruption to the magnetic or electric currents which circulate through the earth, may not some- times occasion earthquakes acting almost instantaneously under large portions of the globe. If, as some philosophers maintain, there is a central fire under every part of the globe, or if certain spaces only are filled with ignited matter, we can scarcely doubt that chemical changes are taking place, which will also change the electrical relations between the mineral beds. A series of strata may act like the plates of an immense Voltaic battery, and discharge the electricity from one internal part of the globe to another, exciting vibrations that may agitate a whole hemis- phere.":}: 204. Researches concerning the extent and importance of the modifications of the earth's surface, which have resulted from the action of existing causes, have led different philosophers to dis- cordant conclusions relative to the nature of that agency which At what depth beneath the surface must that cause be seated ? How does this appear ? In what light are volcanos to be considered in reference to internal fires? Which of the imponderable agents, besides heat, is probably concerned in producing the changes now in progress on the globe ? What analogy lias been supposed to exist between terrestrial strata and Voltaic plates ? * Introduction to Geology, p. 373. t Bertrand Lettres sur les Rev. du Globe, p. 69. J Bakewell's Introd. to Geology, p. 375. GEOLOGICAL SPECULATIONS. 369 produced the rocks composing the crust of the earth, and occa- sioned the dislocations and changes they have undergone at far distant and unknown periods. While some assert the efficiency of the causes now in action, others represent them as inadequate and insignificant. With regard to the effects of winds, currents, and other modifying causes, Mr. Conybeare has the following remarks: 205. "These actions appear to be circumscribed within very narrow limits : over a great part of the earth's surface the influence of these wasting causes is absolutely null, the mantle of green- sward that invests it being an effectual protection. The barrows of the aboriginal Britons, after a lapse of certainly little less, and in many instances probably more, than two decads of centuries, retain very generally all the pristine sharpness of their outline ; nor is the slight fosse that sometimes surrounds them in any degree filled up 206. " Causes, then, which in two thousand years have not affected in any perceptible manner these small tumuli, so often scattered in very exposed situations over the crests of our hills, can have exerted no very great influence on the mass of those hills themselves in any assignable portion of time, which even the imagination of a theorist can allow itself to conceive ; and where circumstances are favourable to a greater degree of waste, still there is often a tendency to approach a maximum at which fur- ther waste will be checked ; the abrupt cliff will at last become a slope, and that slope become defended by its grassy coat of proof. 207. " It should appear, that even the action of the sea, certainly the most powerful and important of all those we have surveyed, has a similar tendency to impose a limit to its own ravages. It has obviously in many instances formed an effectual barrier against itself, by throwing up shingle-banks and marsh-lands in the face of cliffs against which it once beat ; and after the de- struction has been carried to a certain point, it appears necessary from the mode of action, (excepting where very powerful currents interfere,) that the very materials resulting from the ruin should check any further increase ; even where these currents exist, these also have a tendency to throw up barriers of shingle in their eddy. Historical records, and the very nature and physical possibilities of the case, alike compel us to dissent entirely from those crude and hasty speculations, which would assign to the causes now in action, the power of producing any very material change in the face of things ;"and which would refer to these alone, acting under their present conditions, and with only their What effect has vegetation on the rapidity of changes on the earth's surface ? How is this exemplified in Great Britain? What limits the power of the ocean to wear away its shores ? 370 GEOLOGY. present forces, the mighty operations which have formed and mo- dified our continents."* 208. Mr. Conybeare does not here distinctly mention earth- quakes and volcanos among the existing causes of alteration of the surface of the earth ; and as he could not have overlooked their influence, it is probable that he regarded their action as being too limited to produce any considerable effect. Mr. De la Beche, who also asserts the dissimilarity of the ancient and mo- dern modifying causes of terrestrial conformation, makes the following observations on the phenomena to which we have just alluded : 209. *' If we withdraw ourselves from the turmoil of volcanos and earthquakes, and cease to measure them by the effects which they have produced upon our imaginations, we shall find that the real changes they cause on the earth's surface are comparatively small, and quite irreconcilable with those theories which propose to account for the elevations of vast mountain ranges, and for enormous and sudden dislocations of strata, by repeated earth- quakes acting invariably in the same line, thus raising the moun- tains by successive starts of five or ten feet at a time, or by catas- trophies of no greater importance than a modern earthquake. It is useless to appeal to time : time can effect no more than its powers are capable of performing: if a mouse be harnessed to a large piece of ordnance, it will never move it, even if centuries on centuries could be allowed ; but attach the necessary force, and the resistance is overcome in a minute."f 210. Among those writers who have taken the opposite side of the question, and maintained the efficacy of causes now operating to have produced the more ancient modifications of the surface of the earth, Mr. Lyell has distinguished himself by the learning and ability displayed in support of the opinions he has adopted. The full force of his arguments can only be appreciated by those who have the opportunity for examining the extensive mass of information which he has collected in his treatise on " The Prin- ciples of Geology."j~ The following are some of the important remarks and inferences which he has deduced from the considera tion of existing phenomena, and of the degree of analogy observa- ble between ancient and modern formations : 211. "It is undeniable that many objections to the doctrine of the uniform agency of geological causes have been partially or What objection has been raised to the supposition that changes in tho earth's surface are due to causes now in action ? What distinguished writer has maintained the. affirmative of that hypo- thesis ? * Outlines of the Geology of England and Wales, by Conybeare and Phillips, pt. i. 1822. Introduction, pp. 32, 33. t Geol. Man., pp. 148, 149. t See especially Book II., contained in the 1st and 2d vols. of tho third edition. GEOLOGICAL SPECULATIONS. 371 entirely removed by the progress of the science in the last forty years. It was objected, for example, to those who endeavoured to explain the formation of sedimentary strata by causes now in diurnal action, that they must take for granted incalculable periods of time. Now the time which they required has since become equally requisite to account for another class of phenomena brought to light by more 'recent investigations. It must always have been evident to unbiassed minds, that successive strata, con- taining, in regular order of superposition, distinct beds of shells and corals, arranged in families as they grow at the bottom of the sea, could only have been formed by slow and insensible de- grees in a great lapse of ages : yet, until organic remains were minutely examined and specifically determined, it was rarely possible to prove that a series of deposits met with in one country was not formed simultaneously with that found in another. But we are now able to determine, in numerous instances, the relative dates of sedimentary rocks in distant regions, and to show by their organic remains that they were not of contemporary origin, but formed in succession." 212. " We cannot reflect on the concessions thus extorted from us, in regard to the duration of past time, without foreseeing that the period may arrive when part of the Huttonian theory will be combated on the ground of its departing too far from the assump- tion of uniformity in the order of nature. On a closer investigation of extinct volcanos, we find proofs that they broke out at suc- cessive eras, and that the eruptions of one group were often con- cluded long before others had commenced their activity. Some were burning when one class of organic beings were in existence, others came into action when a different and new race of animals and plants existed : it is more than probable, therefore, that the convulsions caused by subterranean movements, which seem to be merely another portion of the volcanic phenomena, have also occurred in succession ; and their effects must be divided into separate sums, and assigned to separate periods of time. 213. " Nor is this all : when we examine the volcanic products, whether they be lavas which flowed out under water or upon dry land, we find that intervals of time, often of great length, inter- vened between their formation, and that the effects of single erup- tions were not greater in amount than those which now result from ordinary volcanic convulsions. The accompanying or preceding earthquakes, therefore, may be considered to have been also suc- cessive, often interrupted by long intervals of time, and not to How has the objection of want of time for sedimentary deposits been met? What data have we for determining the dates of sedimentary rocks? How do the known facts respecting volcanos prove a succession of geological eras ? What difference in the products of volcanos tends to establish the same general truth ? 372 GEOLOGY. have exceeded in violence those now experienced in the ordi- nary course of nature." " It was contrary to analogy to suppose that nature had been at any former epoch parsimonious of time and prodigal of violence to imagine that one district was not at rest, while another was convulsed that the disturbing forces were not kept under subjection, so as never to carry simultaneous havoc and desolation over the whole earth, or even over one great region."* 214. It must he impossible to form any correct judgment as to the relative probability of these conflicting estimates of the in- fluence of those natural causes now in action on the structure and conformation of the crust or exterior portion of the terrestrial globe, without a previous acquaintance with the observations that have been made on the visible phenomena of the early formations, and the displacements and modifications to which they have evidently been subjected. Hence it will be requisite to take some notice of the great convulsions of the surface which have left indelible traces of their occurrence; and also to give a brief de- scription of the usual appearances of rocks, and of their modes of consolidation, stratification, and juxtaposition. What argument in favour of present causes is afforded by the Ameri- can lakes ? (Note.) How is the objection to that argument answered by Boue? By what observations may we be enabled to judge of the correctness of any theory concerning present or past causes of change in the eanifs crust ? * Prin. of Geol., vol. i. pp. 126 129. As an argument for the probability that ancient deluges were owing to causes similar to ihose now in opera- tion, Mr. Lyell observes that " the existence of enormous seas of fresh water, such as the North American lakes, is alone sufficient to assure us, that the time may come, however distant, when a deluge may lay waste a considerable part of the American continent." Mr. Convbeare, in a paper published in the " Annals of Philosophy, 1830 and 1831," endea- vours to invalidate the reasoning of Mr. Lyell, by a comparison of the effect produced by the cataract of Niagara, with the erosive action of the current of the Thames, in scooping out ihe valley through which it flows, alleging that according to the fluviatile hypothesis of the formation of valleys, that of the Thames must have been hollowed out by that river, in the course of the same period of time during which the waters of the lakes have only worn a channel seven miles in length. But M. Boue remarks, that " the hollowing out of the valley of the Thames and its lateral banks, commenced not merely since the tertiary epoch, but long anterior to it, since the valley traverses very different formations; while, on the con- trary, the cataract of Niagara was formed in the alluvial modern or Jovian period of M. Brongniart." Previously to that epoch he alleges that the American lakes emptied themselves into the Mississippi, and that the course of their outlet was changed by volcanic phenomena, of which there are still some traces in Canada and the northern United States. See a French translation of Mr. Conybeare's " Examination of those Geo- logical Phenomena which appear to have the most immediate Connection with Theoretical Opinions," by M. Boue, with Notes, in his " Memoires Ge"ologiques," vol. i. NATURAL AND EXCAVATED VALLEYS. 373 Excavation of Valleys, Denudation of Surfaces, and Elevation of Mountains and Continents. 215. The great diversity of appearance of the surface of the earth is caused chiefly by the occurrence of valleys and mountains ; and an inquiry into the circumstances of their formation, so far as they can be ascertained from existing appearances, may serve materially to enable us to appreciate the nature of the power by which they were originally produced or subsequently modified. 216. Valleys have sometimes been distinguished into two classes, termed natural valleys and excavated valleys. The origin of the former is ascribed by Werner to original inequalities of the deposits which form the surface of the earth. Valleys of this kind might originate from the gradual desiccation of a lake ;* and precipitations of solid matter from the water might obviously take place, without causing any considerable alteration of the figure of the basin. For the depositions, might form strata, of equal thickness on the bottoms and sides of the cavity, so as only to lessen its size ; or if the water dried away very gra- dually, the deepest deposit would be in the centre, and the basin might still preserve nearly the same outline. 217. It may easily be conceived, however, that the deposit may be so arranged as to cover the bottom of the lake, fill up any irre- gularities, and alter more or less the form of the cavity, rendering it shallower, and in place of a deep lake, leaving a val- ley with a level surface at the bot- tom. The subjoined figure exhibits sections of two valleys of dif- ferent extent, the lighter part marking the outline of the solid rock, and the darker the deposits of gravel and detritus which have partly filled the cavities. Such valleys, where the super- ficial strata are undisturbed, may be regarded as being coeval with the formation of the tract in which they are situated. 218. Excavated valleys, or valleys of erosion, exhibit very dif- ferent appearances. These occur in hilly and mountainous countries, while the former may be found in the midst of extensive plains. The excavation of valleys may take place under a variety of circum- stances, producing corresponding irregularities of conformation. When strata which were once continuous are broken and swept How have valleys been distinguished ? What is the peculiar character of the first class 1 How may we account for the deposits in drained lakes? How do valleys of erosion differ from natural valleys ? * For a case of this kind see Mr. R. C. Taylor's Paper on the Kisha- coquillas valley, in Mifflin county, Pennsylvania. Trans, of Geol. Soc. of Pa-, vol. i. p. 194. ED. 374 GEOLOGY. away by a torrent of water, if the beds were arranged horizontally, the opposite sides of the valley would present similar rocks at the same elevation ; while the alluvial soil or looser deposits would form the summits of the adjacent eminences, as represented in the marginal figure. 219. Sometimes, however, the appearances are very dif- ferent. The opposite strata of a valley not being arranged horiaontally, but inclined at a certain angle, beds of the same rock form ascending lines on one side, and descending lines on the other, as may be perceived in the following figure. In this section it will appear, that the stratum ff, which forms the summit of the hill on one side of the valley B, descends to the basis of the hill on the opposite side of the same valley. Instances of this kind not unfrequently occur; and they are obviously owing to the different beds having been tilted or upraised simul- taneously by an earthquake, or some other convulsion of nature, previously to the scooping out of the valley and removal of those portions of once continuous strata which had occupied its site. 220. When the beds thus cut through and partially swept away consist of well characterized rocks, such as would be recognized without difficulty, if found in masses, either large or small, far from the strata still remaining in situ , and when such shapeless fragmeats are found at a distance from the former, it may naturally be concluded that they, at some preceding period, filled the now open space. If, then, it appears that these de- tached masses have not sharp angles and edges, but are worn and rounded, it must be inferred, especially if the rock be hard and compact, that the blocks or pebbles had been subject to violent attrition against each other, in the course of their long and distant transport j and that the same deluge that had occasioned their How may valleys of erosion exhibit different positions of the original strata ? What inference do cases pf this kind enable us to draw in regard to the relative ages of river beds, arid their subjacent rocky strata? What are we allowed to suppose has been the origin of water worn Atones in the beds of rivers ? ERRATIC ROCKS. 375 disruption, or exposure to subsequent action of a similar descrip- tion, had reduced them from an angular to an oval or globular shape, like the water-worn pebbles on the sea-beach. 221. Now there are to be met with in many countries on the surface of the earth masses of different sizes, and of every variety of rock ; some of these are large and angular, as is the case with the vast blocks of granite strewed over the surface of several parts of Germany, and which have been referred to the granitic chains of the Norwegian and Swedish mountains, as their original position. Other portions of transported matter are small and rounded, as may be observed with respect to the gravel so largely distributed over many countries, and which is found in thick and extensive beds in England. This gravel is almost entirely flint, formerly contained in the chalk-strata, which seem to have once covered nearly the whole of the south-eastern part of that country, from some districts of which it has been carried away, at a distant period, by a great flood or floods, which softened and washed off the lighter chalk, leaving the more compact and heavier flints behind. 222. Great masses of rock and transported gravel are found in the north of England. Professor Buckland observed among the gravel of Durham twenty varieties of slate and greenstone, which do not occur, in situ, nearer than the lake district, of Cumberland. He also mentions a large block of granite at Darlington, of the same nature with that at Shap, near Penrith ; and other blocks of this granite are found in different parts of Durham.* Professor Sedgwick notices large transported bouldters on parts of the Der- byshire chain of hills overhanging the great plain of Cheshire. He observed boulders arid pebbles at the base of the Cumberland mountains, which must have been transported across the Solway firth, from Dumfriesshire. On a hill near Heytoncastle, about four miles north-east from Maryport, there are large granitic boulders resembling the rocks of the Criffel ; and among them 3 spheroidal mass, in one direction 10 J feet in diameter. Vast mul- titudes of transported, or, as they have been termed, erratic blocks, are found scattered over the northern counties of England. 223. The blocks of Shap granite, which cannot be confounded with other rocks in the north of England, are not only drifted over the hills near Appleby, but have been scattered over the plain ot the new red sandstone ; rolling over the great central chain of England into the plains of Yorkshire ; imbedded in the transported detritus of the Tees ; and even carried to the eastern coast. f 224. In Scotland, likewise, such blocks abundantly occur, and To what source are the blocks of granite in Germany generally referred? What origin is assigned to beds of pebbles and gravel ? What facts have English geologists observed in. confirmation of this theory ? * Buckland's Reliquiae Diluvianae. t De la Beche's Geol. Man., pp. 187, 188, 376 GEOLOGY. in some remarkable situations ; as in the Shetland islands, where there are boulders, which do not correspond with any known rock in the country, and which were probably derived from the northward. It seems likewise that similar phenomena are observable in the Feroe islands.* 225. " The probability, therefore," says Mr. De la Beche, "as far as the above facts seem to warrant, is, that masses of water have proceeded from north to south over the British isles, moving with sufficient velocity to transport fragments of rock from Nor- way to the Shetland isles and the eastern coast of England ; the course of such masses of water having been modified and obstructed among the valleys, hills, and mountains, which they encountered; so that various minor and low currents having been produced, the distribution of detritus has been in various directions." 226. The continents both of Europe and North America, fre- quently present analogous phenomena of erratic blocks and trans- ported gravel. It is difficult to account for the occurrence of erratic blocks, particularly in certain situations, from which it must be inferred, that they have been carried across the sea, and some- times to great distances. It has been conjectured that these mas- sive bodies might have been imbedded in ice, and thus con- veyed by currents which would have failed to remove them had not their specific gravity been thus diminished. Other hypotheses have been proposed to account for these phenomena, but they are not sufficiently probable to require further notice ; and we shall only remark, in the words of a distinguished writer, that " solu- tions of the problem of erratic blocks seem not very practicable at present." 227. In some districts, immense tracts of strata, several hundred feet in thickness, have been torn from the surface, and the mate- rials all carried off, except some occasional patches, forming the caps of isolated hills, the analogous composition of which shows that they were once parts of a continuous formation. These ex- tensive removals of superficial strata have been termed denuda- tions, of which phenomena Great Britain presents numerous in- stances ; one of the most remarkable of which is that called the denudation of the valley of the Weald, including the district between the north and south Downs, chiefly in the county of Sussex. The geology of this tract has been rendered highly interesting by the researches" and important discoveries of Mr. Mantell, relative to the fossil remains imbedded in some of the strata ; which will be subsequently noticed. The Wealden coun- try is bordered on three sides by chalk hills, which terminate What is inferred to have been the direction of the currents which transported the boulders found in Great Britain ? What suppositions have been advanced to account for the presence of erratic blocks at great distances from their original situations ? What is meant by denudation, in geology ? * Dr. Hibbert, in Edinb. Journ. of Science, vol. vii. t, 6, 6, and also inferior beds of the same nature. In what regions of country are contortions of strata most remarkably exhibited ? In what state must the rocks have been at the time the con- tortions were produced? In what manner may the effect of contortion in strata be imitated ? In what parts of mountain ranges are these phenomena particularly ob- servable ? * De la Heche's Geological Researches, p. 127. t Transactions of the Royal Society of Edinburgh, vol. vii. p. 85. CONFORMABLE STRATA 387 265. In the Alps, between mount Righi and the Hospice of St. Gothard, a series of mixed strata of limestone, clay slates, shales, and sandstones, display such windings and convolutions, as might have been produced in the manner already described, by the com- bined operation of vertical and lateral forces.* Examples of the waving or zigzag direction of strata occur occasionally in coal mines 5 - and at Anzin, near Valenciennes, a remarkable instance has been observed of this derangement of the coal strata, which are bent up and down, and covered by horizontal strata of chalk, marl, and clay, subsequently deposited. f 266. The strata, instead of rising towards the summit of a hill, may be depressed in the centre, as if they had been deposited in a basin, or trough-shaped hollow. The preceding figure represents a series of strata thus arranged, each stratum having the shape of a shallow inverted cone or dome, the edges of which may be traced all round the mountain. In the hill of St. Giles, near Liege, this conformation of the strata may be noticed : sixty-one beds of coal, alternating with rocky strata, form a mountain 3200 feet in height. In South Wales and other parts of Great Britain, the coal strata are arranged in a similar manner. 267. When rocks belonging to different formations occur together, one resting on the other, that which is placed underneath is termed the fundamental rock, and that above it the superin- cumbent. The line where two rocks or formations come in con- tact is named either the line of junction, being veiwed with reference to the position of the rocks, or the line of separation, as marking the distinction of their species. When the strata of a superimposed formation are parallel with those on which they rest, the, stratification is said to be conformable ,- as in the figure, p. 385, where the strata are all horizontal. Inclined strata may also be What example of contorted strata is found in Switzerland ? In what manner are the coal strata at Liege found to be arranged ? What is meant by the terms fundamental and superincumbent, when applied to rocks ? What is the line of junction in stratifications ? * De la Beche's Geological Researches, p. 129. t For an account of the contorted rocks along the valley of the Juniata, oy Mr. R. C. Taylor, see Transactions of the Geol. Soc. of Penn., vol. i. pp. 11 and 182. ED. 388 GEOLOGY. conformable, the same degree of inclination extending through all of them. 263. If, on the contrary, the superimposed strata are horizontal, while the subjacent strata are more or Jess inclined, they are relatively termed unconformable strata. This mode of superposition is shown in the above diagram, re- presenting a section of a part of a mountain composed of primitive, secondary, tertiary, and alluvial stratifications. The horizontal strata, A, B, C, D, of sand, clay, shell limestone, and sandstone, conformable among themselves, are seen reposing uncomformably on the highly-inclined strata of slate and gneiss, E, F, which rest conformably on granite. The strata around Paris, consisting of alternate fresh-water and marine formations, are thus superimposed uncomformably upon chalk, which forms a great basin, containing these various deposits, which also cover its edges in the less elevated parts, while in some places the chalk appears rising through the upper strata. 269. When a series of strata are nearly horizontal, and extend through a considerable tract of country, intersected by deep valleys, the same strata will make their appearance at nearly the same level, in distant mountains. In the vicinity of Pittsburgh, in Pennsyl- vania, particularly along the banks of the Monongahela river, a thick stratum of coal may be traced through many hills at the same elevation above the intermediate valleys. The coal may be worked by driving levels from the sides of the hills, forming open galleries, and thus obtained with little difficulty. Owing to the horizontal position of the coal, it forms the bed of a river, for several miles.* 270. When curved strata of equal thickness at the top and sides lie unconformably on other strata, the former are said to be saddle- shaped; and when such overlying strata gradually become thin- ner from the base to the summit, thus wrapping round the sides of the subjacent or fundamental rock, they are termed mantle- shaped strata. Strata filling up a spheroidal cavity, are denomi- nated basin-shaped ; and if the cavity be oblong, the superimposed strata are styled trough-shaped. To what class of strata is the term unconformable applied by geologists ? How are these strata illustrated in the Paris basin? What are saddle- sJiaped strata ? mantle-shaped ? basin-shaped ? trough-shaped ? * See Am. Journal of Science, vol. xxix., pp. 58 68. ANTICLINAL AXIS. 389 271. The upper part of a stratum or bed, which, rising from under others makes its appearance at the surface, and where it consequently terminates, is designated by miners the outcrop, or basset-edge of the stratum. Strata are said to form outlyers or out- lying rocks, when they compose detached heights, once evidently continuous with extensive tracts of a similar geological struc- ture. Isolated hills of this kind are found on the outskirts of mountain ranges or elevated plains, separated from them by valleys of excavation, as in the Pittsburgh coal strata above men- tioned. 272. Sometimes the continuity of a whole series of strata is interrupted, the beds having been apparently broken through, and shifted or heaved on one side from their original position, consti- tuting what is termed a fault, or slide. These dislocations of strata are phenomena of an analogous nature to the heaving of mineral veins, but they take place on a more extensive scale.* 273. A dyke is a wall of rock interrupting the continuity of strata, and filling up the fissures sometimes caused by faults or breaks. The ends of the strata on either side of the fissure are occasionally tilted or bent upwards, as if the dyke had been formed by the protrusion of matter from below. Dykes vary in thickness, from a few inches to many yards ; and those which intersect coal-beds are composed of indurated clay, or more frequently of basalt. 274. The dip, or inclination of strata, that is, the point of the compass towards which they descend, is a circumstance deserving attention, [t has been observed, that the dip is always at right angles to the range or direction of the strata; and that if the dip is given, the direction may be inferred, but a knowledge of the direction will not give us the dip. The amount of the dip of any strata is to be estimated by the angle which they form with the horizon ; and this may be determined by means of the instrument called a clinometer, which is a compass with an attached quadrant. 275. An anticlinal axis is that line from which the strata com- posing a hill dip in opposite directions. " The ridge of a house- top will convey an idea of this line, and the slope of the roof repre- sent the dip of the strata."f Some rocks, especially those of the trap kind, as porphyries and syenites, are said to be tabular. Dr. Macculloch terms the tables into which these rocks may be divided pseudo-strata.^: " The tabular structure consists of parallel plates of rock, separated by regular seams. This structure has been often confounded with stratification : it appears to be the What is meant by the cropping out of strata ? What are outlyers ? What is a fault or slide ? What is a dyke, in geology ? What is meant by the dip of rock strata? How is it ascertained? What is the anticlinal axis of a series of strata ? * For an account of the structure, arrangement, and composition of me- tallic veins, see Treatise on Metallurgy and Mining, pp. 189 192. t De la Beche's Geol. Man. Appendix, t Geol. Classification of Rocks, p. 90. 2x2 390 GEOLOGY. result of crystallization, and is closely allied to the columnar structure."* 27(5. The only remaining description of rocks that can be con- sidered as symmetrical, with regard to their external structure, are those which have been styled columnar. The most distinctly marked among- the columnar rocks is basalt. The columns they exhibit are formed by the aggregation of prisms generally of a pentagonal figure, but they are liable to desquamation and super- ficial decomposition, when their angles become rounded, and their forms variously modified. Vast ranges of basaltic pillars occur in countries which have been the scenes of volcanic action, as the singular masses called the Giant's Causeway, on the northern coast of Ireland ; and Fingal's Cave, in the Isle of Staffa, one of the Scottish Hebrides. The general appearance of extensive ranges of columnar rocks may be illustrated by the following diagram : 277. Beds of stratified rocks, ff, a, , are cut through by a ba- saltic dyke of horizontal prisms, intersecting also ranges of verti- cal columns, and three large transverse dykes of amorphous basalt, i, 6, above the highest of which are detached masses, d and e, of columnar basalt. This figure likewise exhibits the interior struc- ture of prismatic rocks, and the manner in which the columns are divided by joints. The columns may not only be vertical or hori- zontal, as in the foregoing figure, but also inclined at any given angle, and sometimes the prisms are more or less curved, forming- by their combinations rocks destitute of symmetrical arrangement. 278. Rocks which are neither stratified, tabular, nor columnar, can scarcely be said to have any appropriate form : and we have, therefore styled them amorphous. They may vary in dimensions as much as in figure, and be of any size, even of mountainous bulk. Thus granite, greenstone, and some of the trap rocks con- What classes of rocks have no true stratification ? What are columnar rocks ? What remarkable examples of columnar rocks are found in the British Islands ? Explain the general appearance of stratified rocks? * Bakewell's Introd. to Geology, p. 87. GRANITIC ROCKS. 391 stitute vast pillars, blocks, and boulders, of every fantastic shape. Irregular masses imbedded in other rocks, are styled nodules. They are sometimes rounded, and not unfrequently flattened ; " and in such cases, they pass into the form of non-persistent and extenuated strata. Nodules are often imbedded in stratified rocks ; but they are also found in granite, as is the case with serpentine. The size of these masses varies from a foot to a mile or more."* It is difficult to determine how far stratification extends among the primary rocks ; and even granite sometimes exhibits traces of what Dr. Macculloch calls pseudo strata, f Classification and Arrangement of Hocks. 279. A cursory view of the masses forming the crust of the earth exhibits so much confusion and indefinite variety of composition as must appear to render nugatory all attempts at classification ; and hence it was at one time supposed, that the several formations were destitute of all regularity in distribution and in individual charac- ters. The first rude distinction that seems to have been made was that of the German miners, who arranged strata of rocks in two classes, namely, those containing metallic veins, and those which were non-metalliferous. Lehman, already mentioned, (No. 6,) made the much more important divisions of formations into primi- tive and secondary, or those destitute of organic remains, and those including such fossils. 280. The celebrated Werner modified and improved this divi- sion ; adding two other classes, the transition and the local, or as they were afterwards called, tertiary rocks. Subsequent additions have been proposed of alluvial or superficial deposits ; and of pyro- genous strata, including the trap and volcanic rocks. These divisions have been generally adopted by recent writers on systematic geo- logy ; though several have thought fit to subdivide the secondary and tertiary rocks into distinct groups or formations. 281. In assuming successions of strata to a greater or less ex- tent superimposed around the terestrial globe, we must be careful to distinguish what has been inferred from limited observation, confirmed, however, in a certain measure by uncontradicted expe- rience, from the deductions derived from appearances of an unequi- vocal description. That granite, or rather granitic rocks, constitute, as elsewhere stated, the basis or skeleton of the solid crust of the earth, is a conclusion formed from general observation that these ?, rocks where they most extensively occur seem to rise from under others which are known to occupy relatively low situations, or they What is the nature of amorphous rocks? What is meant, in geological language, by the term nodules ? Who first divided rocks into primary and secondary ? What distinctions were added by Werner? * Dr. Macculloch's Geol. Class, of Rocks, p. 113. t See p. 328. On the subject of stratification in general, see Greenough's Critical Examination of the First Principles of Geology, 1819, Essay I. and Dr. Boase's Treatise on Primary Geology. 392 GEOLOGY. form nearly vertical masses so included between other rocks as to indicate that the granite passes beneath those rocks. Since, how- ever, the extent of surface of granitic rocks naturally or artifically exposed, is but inconsiderable compared with that of the earth's surface, the notion that granite composes the inner shell or lining of the earth's crust, is at best but a probable conjecture. 282. Granite, then, can only be supposed to be an universal for- mation ; and the extent of many of those above it must at present be utterly uncertain. But with respect to some of the superior strata, we know with certainty that they are not universal forma- tions, and that some cover only limited areas. Coal appears to consist of circumscribed beds, formed in basins or concavities of older strata; the clays of the London basin, and the various de- posits of the Paris basin, also compose circumscribed beds. Chalk, if it deserves the character of a general formation, (as it is certainly a very extensive one,) is not now universal, having been removed apparently from some parts of the surface of this coun- try, as the weald of Sussex, England, by the violent action of water. 283. It is only by the gradual accumulation of facts that the boundaries of real knowledge can be extended. From their situa- tion the more superficial rocks may be supposed to have been the most thoroughly investigated, and since it has been ascertained that they include organic remains extremely singular and curious, they have attracted particular attentin : as the progress of re- search proceeds, however, it may be expected that the primordial or inferior rocks will also be more closely examined, and that thus various disputed points with regard to them will be satisfactorily decided. 284. The manner in which the several formations and rocks are arranged so as to form mountain masses may be illustrated by the following representation of a section of the Brocken mountain, in the Hartz forest in Germany. Whence has it been inferred that granite is the lowest of rocky strata? What evidence have we that this rock is universally extended beneath the other strata ? What example of limited formations may be mentioned ? SUBMEDIAL ROCKS. 393 The perpendicular mass in the centre, a, is granite, which may be supposed to extend laterally beneath the other rocks ; , 6, is clay slate, immediately enveloping the granite ; c, c, is transition lime- stone ; rf, rf, gray wacke slate ; e, e, old red sandstone ; /, /, moun- tain limestone,^:, g, gypsum ; A, A, variegated sandstone ; i, ', second or newer gypsum ; j\ j, second limestone ; A-, &, alluvial deposits. It may be proper to observe, that this section exhibits only the ar- rangement and successive declination of the rocks that Ibrm the Brocken,and not their respective forms and dimensions ; and that in other mountains some of these strata may be replaced by others, or be entirely wanting. Synoptical Arrangement of Groups, Formations, and Rocks.* 285. I. Primordial or Non-fossilliferous Rocks. A. Unstratified rocks. Granite, syenite. Greenstone. Serpentine. Schorl rock, &c. B. Stratified rocks. Gneiss. Mica slate. Clay slate. Quartz rock. Grampian hills, in Scotland ; Cornwall ; Dofrine hills, Nor- way; Ural mountains, Russia; Erzegebirge, in Saxony; Ries- engebirge, in Silesia ; Pyrenean mountains ; eastern Alps, from St. Gothard to the plains of Hungary ; Alleghany mountains, United States; Andes, South America. Hornblende slate, &c. 286. II. Submedial Rocks. (Gray wacke Group of Lyelt and De la Beche. Transition Rocks of other Geologists.} Sandstone conglomerate, slate, &c. Calcareous flags, sandstone, and schist. Shell limestone, and micaceous sandstone, &c. Coralline limestone, and argillaceous shale. Argillaceous limestone, and sandy shale. Describe the several parts of which the Brocken is composed ? What individual strata compose the first division of primordial rocks? What name is given to this division ? What constitute the second division of the same class of rocks ? In what parts of the globe are these rocks conspicuously shown? What are the five divisions of the submedial or grauwacke group ? * This synoptical table is chiefly founded on " Table II. Showing the Order of Superposition, or Chronological Succession of the principal Sedi- mentary Deposits or Groups of Strata in Europe." Appendix to Lyell's Prin. of GeoL, vol. iv., with Additions and Modifications, derived from De la Beche's Geological Manual ; Brongniart Tableau des Terrains qui com- potent I'Ecorce du Globe ; D'Aubuisson Traiti de Geopnosie, 2nde edit., continuee par Amedee Burat., torn. i. 1834 ; MantelPs Geology of the South-East of England, chap. ii. ; and Outlines of the Geology of England and Wales, by Conybeare and Phillips, part i. Introduction. 394 GEOLOGY. "The grauwacke group occurs in Norway, Sweden, and Russia. It forms a portion of southern Scotland, whence it ranges with breaks, as far as regards the surface, formed by newer deposits of the sea, down western England and Wales, into Normandy and Brittany. It appears abundantly in Ireland. A large mass of it is exposed in the district constituting the^ Ardennes, the Eifel, and the Taunus. Another mass forms a large portion of the Hartz mountains, while smaller patches emerge in other parts of Germany, on the north of Magdeburg and other places." De la Beche's Geol. Man., p. 430. The terms graywacke or transition are applied as epithets to distin- guish the sandstones, slates, and limestones of this group from those which occur in other groups. In America the grauwacke is distributed over a vast extent of country, from Alabama to the Arctic ocean, and is characterized by fossils which must have lived in a climate of far higher temperature than exists at present in any regions without the tropics.* 287. III. Medial Rocks.] Carboniferous group. a. Old red sandstone. b. Mountain limestone. c. Coal measures, including sandstones, conglomerates, clay with ironstone, shales, and limestones. 288. IV. Supermedial Rocks.jf. (1.) Penean, or red sandstone. (2.) Keupric, or poecilian. '".) Liasic. Oolitic, or freestone. Wealden. Cretaceous. 289. Panean group. a. New red sandstone [Rothliegendes, Germ.] \Gres Rouge, Fr.] b. Magnesian limestone [Zechsttin, Germ.] In what countries are the members of this group found ? How extensively is it distributed on the American continent? What three individuals belong to the carboniferous group ? What groups constitute the class of supermedial rocks? How many and what individuals belong to the penean group ? * See Mr. R. T. Conrad's Paper on the Fossil Shells of the Grauwacke Group, in Trans. Geol. Soc. of Penn., vol. i. p. 267. ED. t See the following note. t The rocks belonging to this and the preceding order, (the medial and supermedial rocks, or those from the old red sandstone to the chalk, inclu- sive,) constitute the secondary formations of the Werneriana. WEALDEN GROUP. 395 290. Keupric group. a. Variegated sandstone, [Bunter Sandstein, Germ.; Ores Bigarre, Fr.] b. Shell limestones, [Muschelkalk, Germ.] c. Red or variegated marls, \Keuper, Germ.] Marnes Irisees, Fr.J 291. Liasic group. a. Alum slate, [Ampelite alumineux, Fr.] b. Dark blue marl, with beds of rubbly limestone sandy marlstone. c. Blue, white, and yellow earthy limestone, interstratified with clay, often slaty and bituminous, [Quadersand- stein, Germ.] 292. Oolitic group. a. Inferior oolite. b. Great oolite, Bath stone, Caen stone. c. Bradford clay, [Marne argilleuse Jurassique, Fr.] d. Forest marble. e. Cornbrash. Bradford clay and cornbrash ought, perhaps, to be regarded as local formations, and to be included under that of forest marble or lithographic slate ; with which, where they occur, they are associated. Burat, indeed reckons Bradford clay, forest marble, and cornbrash, as distinct but consecutive members of the oolitic formation; and Lyell distinguishes the cornbrash from the forest marble. /. Oxford clay dark blue, tenaceous clay ; bituminous shale, sandy limestone, (Kelloway rock.) g. Coral rag, [Calcaire Corrallique, Fr.] calcareous, shelly, oolitic freestone ; coarse limestone, full of corals ; yellow sand ; siliceo-calcareous grits. h. Kimrneridge clay, \_Marne argilleuse Havrienne, Fr.] i. Portland stone coarse, shelly limestone, fine-grained white* limestone, compact limestone all oolitic beds of chert. 293. Wealden group. a. Purbec stone various kinds of limestones, alter- nating with marls. b. Ashburnham stpne bluish-gray limestone, alternat- ing with blue clay, and sandstone shale. c. Hastings sands and clays fawn-coloured and white sand, and friable sandstone, with clays and calcareous grits. How many and what individuals belong to the keupric ? the liasic ? Into how many and what subdivisions is the oolitic group of superme- dial rocks distinguished ? What ii dividual strata compose the wealden group ? 396 GEOLOGY. Wealden group continued. d. Weald clay slaty clay, and limestone, with beds of ironstone, and Sussex marble. 294. Cretaceous group. a. Shanklin sand, lower green sand \Glaucome sab- leuse, Fr.] green, gray, white, and ferruginous sand, with clay, chert, and siliceous limestone. b. Gaut, or folkstone marl blue clay, with veins of red ochre. c. Upper green sand, or firestone [Glauconie crayeuse, Fr.] marly stone, and sand with green particles ; layers of calcareous sandstone. d. Chalk, without flints. e. Chalk, with flints, or upper chalk. The chalk formations, d and e, are very extensive in Eng- land, France, and other parts of the continent of Europe. f . Maestricht limestone soft, yellowish-white lime- stone, with siliceous masses, resembling chalk. 295. V. Superior Rocks. (Supra cetaceous, Tertiary, or Newest Floetz Rocks of different Au- thors.) Lower formations. In England (London basin.) a. Plastic clay. I. London clay, c. Bagshot sand. In France (Paris basin.) a. Plastic Clay. b. Calcaire grossier. 396. Upper Formations. A. Calcareo-siliceous strata, gypsum, and marls, sand and sandstone, millstone grft, and marls. B. Marine deposits of sand, forming the fahluns of Touraine, and of the Lower Loire, France. C. Subapennine marl, subapennine yellow sand ; English crag; and other deposits containing marine fossils. D. Molasse and nagelfluhe accumulations of rolled pebbles and sands, composed of Alpine detritus. E. Limestone, sands, clays, sandstones, conglome- rates, marls, with gypsum; containing marine fossils. What are the six subdivisions of the cretaceous or chalk group ? What are considered in England as constituting the lower formations of the tertiary class ? What distinctions of this class exist in France ? What five divisions are found among the upper formations of this class ? VOLCANIC STRATA. 397 297. VI. Alluvial Deposits. A. Sand and gravel auriferous sands, cascalhao. B. Detritus of various kinds calcareous sand- stone, with broken shells ; osseous breccia. C. Recent calcareous formations coral reefs and islands, tufa, travertin. D. Peat. 298. VII. Volcanic Strata. Ancient Basalt, trachyte, greenstone, &c. Recent Lava, ashes, moya, &c. What are the four divisions of the sixth class formed hy geologists ? How are volcanic strata divided ? What particular substances belong to each division? Works in the Department of Geology. BakewelPs Introduction to Geology with an outline of Profes- sor Sillirnan's course of lectures on the same subject. 1 vol. 8vo. De la Beche's Geological Manual. 1 vol. 8vo. Philadelphia. Lyell's Principles of Geology. 3 vols. 8vo. Ure's New System of Geology. London. 1829. Maclure's Geology of the United States, with a map. Featherstonhaugh's Geological Report to Congress. 1835. Professor Rogers's Report on the Geology of North America, in the Transactions of the British Association at Edinburgh. American Journal of Science, various numbers, particularly volumes xxii. and xxix., the latter of which contains a highly important account of the geological character of the great coal deposits of the valley of the Ohio, and its tributaries, by Dr. Hildreth. Transactions of the Geological Society of Pennsylvania, vol. i. Hitchcock's Report of the Geology of Massachusetts. 1 vol. 8vo. 1833. Transactions of the Geological Society of London. 5 vols. 4to. Mantell's Geology of the South-East of England. 1 vol. 4to. Journal of the Acadamy of Natural Sciences. 7 vols. 8vo., hitherto published. 2L ORYCTOLOGY. 1. THE term Oryctology* has been employed to denote the na- tural history of minerals and fossils, with special reference to the situations they are found to occupy within or upon the crust of the earth. Mineral and fossil are words of analogous signification, implying bodies that have been obtained by mining or excavation; but the former is now usually appropriated to those bodies which are mere chemical compounds, exhibiting no traces of organization; and the latter to such as retain in any degree the form and appearance of animal and vegetable substances, however changed or modified as to their composition. These bodies might be generally designated metamorphosed organic remains, were they not sometimes pre- sented to us by nature absolutely unaltered, as in the very remark- able instance of the fossil elephant, found embalmed in ice, in Siberia, in the beginning of the present century. 2. From the structure and composition of animal and vegetable substances, however, it necessarily follows, that but very few comparatively can occur in such a state of complete preservation. Trees are sometimes found buried in bogs and mosses, standing erect, with their roots and branches very little altered. The more dense and compact parts of organized beings are most frequently preserved, while the softer substances which entered into their composition have been destroyed or removed. Hence whole skeletons, or detached bones, and shells, either entire or broken, are among the most common fossilized organic remains. They occur, however, under variously modified conditions : some having undergone little change of substance, as those masses of shells To what does the term oryctology apply ? What remarkable instance can be mentioned of a specimen of extinct animals found entire ? What vegetable fossils are sometimes discovered in their natural positions? What parts of organized beings are commonly wanting in fossil specimens? How is this exemplified in carbonate of lime ? * From the Greek 'Opuxrdj./ossi'Z, and Aoyoj, a discourse. 398 ENCRIMTES. 399 and corals, which being conglutinated by carbonate of lime, form blocks or beds of variegated marble* The preceding figure represents the surface of a slab of Kil- kenny marble, inlaid with shells and coralloids, which have a very pleasing effect ; and many of which are so perfect, that their forms may be traced, and their species distinguished. 3. The Sussex or Petworth marble is another kind of shell limestone, which affords beautifully-veined sections, and has been used for ornamental purposes. It is found in layers varying from a few inches to a foot or more in thickness, in the weald clay, in the south-eastern part of England. " This limestone is of various shades of bluish-gray, mottled with green and ochraceous yellow, and is composed of the remains of fresh-water univalves, formed by a calcareous cement into a beautiful compact marble. It bears a high polish, and is elegantly marked by the sections of the shells which it contains : their constituent substance is a white crystallized carbonate of lime, and their cavities are commonly filled with the same substance, presenting a striking contrast to the dark ground of the marble. In other varieties, the substance of the shells is black, and their sections appear on the surface in the form of numerous lines and spiral figures. Occasionally a few bivalves (cyclas} occur, and the remains of the minute crustaceous coverings of the cypris faba very constantly."* This limestone is durable; "yet from long exposure in damp situations, it undergoes decom- position, and the petrified testacea may then be extricated almost entire."f 4. The mountain limestone, called by Mr. Bakewell, " upper transition limestone," " is one of the most important calcareous rocks both from its extent, the thickness and number of its beds, the quantity and variety of its organic remains, and its richness in metallic ores, particularly of lead. In Derbyshire, where the different beds of limestone have been pierced through by the mi- ners, the average thickness of the three uppermost is about 160 yards: the beds are separated by beds of trap or basalt, resem- bling ancient lavas. The lowest limestone has not been pierced through." 5. " The prevailing characteristic organic fossils are encrinites and madrepores. The upper beds of mountain limestone, in Derbyshire, appear to be almost entirely composed of encrinites."^: Polished slabs of entrochai or encrinital marble are sometimes What is the substance which has replaced animal matter in the fossa shells in marble ? Which appears to be the more durable the testaceous fossils, or their interposed cement ? What is mountain limestone in geological nomenclature ? What are its prevailing fossils ? * Mantell's Geology of the South-East of England, p. 184. t Idem, p. 186. } Bake well's Introduction to Geology, p. 131. 400 ORYCTOLOGY. employed for tables and other ornamental furniture. A portion of such a table is exhibited in the following figure. The table, from which the above was taken, is of a lig-ht gray colour, variegated with white ; but the mountain limestone has oc- casionally a black, and sometimes a reddish-brown ground, or is veined or clouded. 6. Beds of black marble, with madrepores, are found in various parts of England and Wales. The black tint of this marble is owing to the presence of bitumen: it is otherwise generally com- posed of nearly pure carbonate of lime, except some beds, which consist partly of carbonate of magnesia. 7. Sometimes the organic remains are found to have undergone considerable modification as to their composition, while their forms exist unaltered. Thus vegetable bodies are changed into ochraceous earth or tuff, like the umber found in the environs of Cologne. Wood impregnated with silex is not unfrequently met with in various parts of the world ; but the finest specimens are said to be obtained from the vicinity of Schemnitz and at Telkobanya, in Hungary. It also occurs in the diluvian detritus, in the green sand of the cre- taceous group, and in the Portland stone. The texture of wood may be traced in some siliceous minerals, as jasper, agate, cal- cedony, opal, and pitchstone, betraying their ultimate origin. Argillaceous earth may cause the mineralization of wood ; and different parts of vegetables are often imbedded in the rocks com- posed of this earth. Iron in the state of sulphuret, or in that of carbonate, may pervade the substance of vegetable fossils. " In- numerable seeds, seed-vessels, &c., have been found, by Mr. Crow and others, in the blue clay of Sheppey, in the state of pyrites. Most of these belong to plants unknown to our bota- For what purposes in the arts is this marble employed ? To what does black marble owe its colour? To what changes arc fossils found to have been subjected ? In what situations is wood found to be replaced by silex ? Jn what state may iron exist in the forms of vegetable fossils? BOVEY COAL. 401 nists ; the existing plants to which the others seem to approximate are some of those of the warmer climates."* 8. Wood is occasionally impregnated with pyritical or carbonated copper, the latter forming very beautiful fossils, the finest speci- mens of which (consisting of charred wood, marked with the most vivid blue, and green tints, with patches of the carbonate in the state of malachite) are obtained from the copper mines of Siberia.f Volkmann and other authors have mentioned fossil wood im- pregnated with silver ; but its occurrence is somewhat questiona- ble.}: Specimens of wood thoroughly impregnated with galena (sulphuret of lead) have been found in Derbyshire. 9. As might be expected from their original composition, vegetable fossils are often found to have undergone changes which have reduced them nearly to the state of carbonaceous or bituminous minerals. Schookius relates, that masses of bitumen are frequently found among peat ; and sometimes resembling, in size and figure, walnuts, eggs, and pine-nuts.|| Wood is also found in the state of jet, lignite, and Bovey coal. This last mentioned fossil, which occurs in several successive strata at Bovey, near Chudleigh, in Devonshire, extending for some miles, has been worked for more than a century, being used for fuel in burning lime and for other purposes. 10. The preceding figure represents a fragment of Bovey coal. "This variety is evidently a dicotyledonous or gymnospermous phanerogamic plant, for it presents all the external characters of In what states may copper be found in the forms of vegetable fossils ? Lead ? What constituents of vegetables are most frequently found in de- posits of ancient timber ? * Parkinson's Outlines of Oryctology : an Introduction to the Study of Organic Remains. 2d edit. 1833. p. 27. t See Parkinson's Organic Remains of a Former World. 2d edit. 1833 vol. i. pp. 388, 389. { Idem, p. 390. See Martin's Outlines of an Attempt to establish a Knowledge of Ex- traneous Fossils on Scientific Principles, p. 150. li Parkinson's Organic Remains, vol. i. p. 208. 402 ORYCTOLOGY. stems belonging to that class."* Here the trails of the woody tissue are very distinct, and the structure but little altered. This fossil is only found in the superior strata ; but the remains of vegetables are likewise abundant, as might be anticipated, in the coal formation, where however they occur, in general, more entirely metamorphosed. The annexed figure is a representaton of a stro- bilus or cone of a pine, (Pinus antiqua,} which has been completely carbonized. 1 1 . The transformation in some cases is so complete, that though the forms and even the colours may be preserved, all the elements of an organized being have been removed by the mysterious operations of nature. Such bodies are mere casts of the originals, and it not unfrequently happens that branches of trees, or some other parts of vegetables, or those of animals, having been inclosed in stony matter, the original substance has disappeared, but on dividing the lapidescent table, the impression of the organized bodies will be found on one layer, and casts in relief on the other. 12. In general the inferior surface of leaves is displayed in relief, and the superior is indented. The small veins and hairs that mark these surfaces are occasionally preserved in perfection, apparently, while not a particle of animal or vegetable matter re- mains in the stone, the whole having been volatilized. The follow- ing figure exhibits, a mould or impression of a branch of a tree, For what purposes is the mineralized wood, termed Bovey coal, applied ? What class of vegetables must have entered into the composition of that stratum of fossils? Why is it more important to study the internal struc- ture of fossil vegetables than of those which are recent? In what manner may we obtain correct ideas of the forms of vegetables, when the original matter has entirely disappeared ? Which surface of a leaf appears to have resisted most effectually the compressing effect of the strata in which it has been imbedded ? * The Internal Structure of Fossil Vegetables found in the Carbonife- rous and Oolitic Deposits of Great Britain, described and illustrated. By Henry T. M. Witham, of Lartington, F. G. S , F. R. S. E, &c. Edinburg, 1833. 4to. p. 50. To the finely-executed plates which accompany this work, we are indebted for the figure in the text, and for those of some of the vegetable fossils represented in the following pages. Mr. Witham has contributed much, by his skilfully conducted researches, towards ob- taining an accurate knowledge of the internal structure of fossilized stems of plants; and by an improved method of cutting and polishing those bodies, so as to adapt them for microscopical examination, he has been en- abled to elucidate their intimate organization, and thus to afford the most essential means for ascertaining their relative affinities with the genera and species of existing vegetables : a circumstance obviously of the highest importance with regard to the bodies of which the more characteristic portions, the ibliage and organs of fructification, have very rarely escaped destruction. FOSSIL ZED PLANTS. 403 with leaves resembling the fir or yew, on shale, or limestone ; on the margin of the mass are traces of some other vegetable, probably a fern. i 13. Among the fossilized remains of vegetable foliage, the most abundant, especially in the shales and argillaceous schists above the coal, are those which belonged to different kinds of ferns. It is, however, very difficult to identify them with living species. Dr. Woodward states, that out of one hundred and thirty-eight specimens which he submitted to the examination of four eminent botanists, they were able to point out only eleven which bore a decided resemblance to those now existing, and twenty-three were totally unlike any English plant.* 14. Mr. Parkinson laid some fossilized ferns, of which he has given figures, before Sir James E. Smith, who observed, that "these fossil remains of vegetables are a sort of botanical riddles ; and with respect to those which appear to be ferns, the difficulty of determining to what species the several representations may be referred, is augmented by their being so many things which they nearly resemble, without being the same." He spoke doubtfully of almost all of them, but conjectured that they were all foreign, and productions of a warm climate.f The annexed figure repre- sents the impression of a branch of fern, and others will be given in a subsequent page. What class of vegetable remains is found most abundant in shales and clay slates ? What difficulty opposes their acccurate determination ? What change of climate appears to have taken place in the temperate zones since those vegetables were produced ? * Dr. Woodward's Natural History of English and Foreign Fossils, 1729. vol. i. ; Catalogue of English Fossils, part ii. p. 9. t Parkinson's Organic Remains, vol. i. pp. 416, 417. 404 ORYCTOLOGY. 15. Mr. Parkinson questions the existence of antholithes, or fos- sil flowers, or at least asserts that it is merely conjectural. He says: "The tender and almost succulent substance of the petals, stamina, and pistilla, will furnish very little reason for supposing that they should resist a destructive resolution, sufficiently long to allow them to pass through those chemical changes, by which such duration would be given to their original forms, as would secure their passing unchanged in their figure from the vegetable to the mineral kingdom." 16. The existence of impressions of flowers in the fossil state, has been fully established by their presence in specimens where they are clearly developed. Floral forms may thus be exhibited, so that their resemblance to those of recent plants may sometimes be traced, as in the marginal figure, which re- presents a mould or impression of a radiated or stellated blossom, apparently of a syngene- sious plant, like the marigold or China aster. 17. It is certain that " the earlier writers on this science too frequently admitted resembla'nces, when the connexion between the supposed model and the archetype were too equivocal to authorize them. Thus Mylius imagined that he traced the flower of the mouse-ear on a flint, and the rose of Jericho on a schist, from Manebach, both of which M. Walch believes were in reality merely impressions of troehites."* Fanciful as the analogies undoubtedly were by which some authors have been led _ to describe certain fossils as antho- lithes, there can be no doubt but flowers as well as leaves, have sometimes been imbedded in rocks in such a manner that their forms have been more or less preserved, furnishing casts or impressions. The annexed figure exhibits a beautiful impression on sandstone of a branch of a tree, with long lanceolate leaves and blossoms, or rudiments of blossoms. 18. In the case of shells, corals, or other bodies included in lime- Why cannot the parts of fructification be resorted to for determining fos- sil plants ? Have we no example of the preservation of those parts ? What errors on this subject were committed by the earlier writers? Parkinson'* Organic Remains, vol. i. p. 437. GEOLOGICAL ARRANGEMENT OF MINERALS, &C. 405 stone and sandstone rocks, the whole organic substance may be dissolved and canied away, leaving a cavity in the rock bearing the impression of the foreign body, and in this cavity is a mould or cast of the interior. Thus the screwstones, as they are called, have been cast or moulded in the cavities of crinoidal columns. "The most extreme case of mineralization or petrifaction is pro- duced by a process in addition to that just described, when the cavity left by the removal of the shell or coral is again filled up by crystals of calcareous spar, deposited by water filtrating through the stone. Sometimes only a few crystals connect the inner mould or cast to the exterior impression, but generally the whole cavity is filled by the spar, which thus represents truly the shape of the original body, but displays no trace whatever of its internal texture."* 19. With respect to the changes that organized bodies undergo, they must be influenced considerably by the nature of the con- taining rock. " In the green sand almost all the shells are sili- cified ; in the oolitic rocks many are changed to calcareous spar ; in the clays very slight changes have happened to any of the organic remains. On the other hand, the original nature of the organic substance has very much influenced its mode of conservation. Echinital and crinoidal remains are almost invariably converted to a peculiar kind of opaque calcareous spar, in whatever strata they occur : gryphaeae and astreeee retain their laminae ; inocerami and belemnites their fibres. 20. As to vertebrated animals, " their soft portions have perished, but their teeth, bones, and scales remain, either connected or sepa- rated in consequence of the decay of the ligaments, cartilages, &c. The hardening ingredient of bones is principally phosphate of lime, that of teeth is a mixture of phosphate and carbonate of lime. It is generally the fact that their gelatinous or membranous portion has been diminished, and their earthy admixture increased, by the subterranean chemistry to which they have been subjected, and, in consequence, their specific gravity is much augmented."f Geological Arrangement of Minerals and Fossils. 21. There are two modes of formation to which the origin of the rocks composing the crust of the earth might be ascribed. "The first consists in the more or less rapid consolidation of masses which had been previously in a dissolved state ; and the second in the gra- How are screwstones produced ? On what circumstance does the degree of change from a recent speci- men to its fossilized state mainly depend ? What is the mineral which replaces organized matter in the green sand formation ? * EncyelopJEd. Metropol. Treatise on Geology, vol. iv. p. 548. t Idem. 406 ORYCTOLOGT. dual deposition of solid matter from a fluid with which it had been mechanically or chemically combined. Vast fields of ice, and beds of lava, are occasionally or periodically formed at present, by the more sudden process of solidification ; and layers of silt and sand, and beds of travertin limestone, are produced by the slower method of precipitation. The inferior unstratified, as well as the trap rocks, are usually considered as being, like those of volcanic origin, the results of igneous fusion and congelation. But all the stratified rocks are regarded as aqueous deposits, and these, which are by far the most numerous, must have owed their existence to the protracted operations of nature. 22. The stratified rocks, from the graywacke series to the ter- tiary and alluvial formations, include a multitude of distinct de- posits, most of which inclose organic remains derived from suc- cessive races of animals and vegetables, comparatively few of which, except in the upper formations, seem to have any living congeners, but on the contrary, many of these relics present us with the forms of strange beings that once peopled the earth, and which have ceased to exist for countless ages past. Rocks ar- ranged in strata, one above another, may, by their peculiarities of structure and contents, afford the means for ascertaining their re- lative age, or rather order of formation. 23. " Geognostic epochs," says Brongniart, "are very different from chronological epochs : the latter are determined by the suc- cession of time, but not so the former, which are founded on the grand phenomena or catastrophies that limit a geognostic period. By this term we designate the whole time during which the same geognostic phenomena have taken place on the surface of the earth. These periods may amount to numerous ages, or to only a few years: thus the space of time during which the granite dis- played itself over all parts of the surface of the globe, accompanied by the minerals which it contains, forms a remarkable geognostic period. That in the course of which the trilobites existed, with their contemporary organized beings, whilst the argillaceous schists and the carboniferous and bituminous limestones were depo- sited, was another geognostic period, of which the average duration of the life of a trilobite, and the number of the generations, if it were possible to discover them, might loosely indicate the duration. 24. We have another remarkable example of a geognostic period in the state of repose which seems to have prevailed in the crust of the earth, since the existing continents have received their forms and limits, the sea assumed its level, and the atmosphere its temperature; since the animals and vegetables that inhabit the In what two modes may the strata of the earth's crust have been formed ? What is generally supposed to be the origin of granite, gneiss, and trap rocks ? What striking trait distinguishes the fossil animals in the lowest beds in which their remains are found ? How are geological ages or periods to be distinguished from chronolo- gical periods ? INFERIOR ROCKS. 407 sea, or live on the surface of the earth, have varied but little from what they are at present ; this state of repose, established by all observations, all historical traditions, constitutes the last geognos- tic period, the commencement of which must be dated at least four thousand years ago, and which may extend for a long series of ages to come. 25. " As we are ignorant whether the arrangement of the dif- ferent groups is similar over the whole globe, it is impossible to determine whether the geognostic periods have been of equal extent, and also contemporaneous over the surface of the earth. For instance, whether since the ammonites and the belemnites have ceased to live, and the chalk to appear in Europe, in order to be succeeded by the cerites and the tertiary deposits, the first mentioned cephalopodous molluscs have not continued to exist, and the chalk to be deposited in India and in America.* 26. From the preceding observations, it must be concluded that though certain European groups or formations may be charac- terized by the presence of particular fossils, the same formations may occur in other quarters of the world unaccompanied by such fossils, or the fossils may be found in rocks differing in mineralo- gical composition from those in which they appear in Europe. It is, however, a point of importance to be enabled to discriminate, by reference to their contents, the rocks of a single continent, or even those of any one country ; and thus far, at least, it may be admitted that geognostic oryctology has advanced. f Primordial or Inferior Hocks. 27. These rocks are negatively characterized by the absence of any organic remains, or conglomerated fragments of transported matter; whence it may be inferred that, however they might have been produced, they underwent the process of consolidation in a short space of time ; unlike the sedimentary rocks, which were formed by gradual and successive deposition. It is also supposed, that since there are no relics of animals or vegetables in the strati- fied inferior rocks, their formation must have preceded the existence of organized beings on the surface of the earth. 28. The inferior rocks, (including in that appellation the gray- How might we calculate the duration of the period in which carboni- ferdus limestone was formed ? What extent of observations would be necessary in order to determine the relative duration of geognostic periods? What classes of rocks are wholly destitute of organic remains? What may we infer respecting the time at which animals first existed, compared with that at which primitive strata were at the surface of the globe ? ' Tableau des Terrains qui composent 1'Ecorce du Globe. Introd. pp. 8, 9. t The observation of strata and the examination of fossils prove that every European group has its equivalent in America. EJ>. 408 ORYCTOLOGY. M| wacke formations, from which some of the lower rocks can scarcely be distinguished) are the grand repositories of mineral bodies. Among them are found the metals and metallic ores, the gems, and other rare and curious mineral compounds. These, indeed, oc- casionally occur in the ascending strata ; but it will in general be evident that such minerals have been detached from their ori- ginal situations, and dispersed by some convulsions of nature ; as is the case with diamonds, which are found enveloped in the cascalhao, a comparatively recent deposit in Brazil ; with the gold dust obtained from fluviatile sands, and the stream-tin of Corn- wall. 29. Some metals, as tin, tungsten, and molybdena, are almost exclusively the produce of the primordial rocks, or are imme- diately derived from them ; and gold, silver, lead, copper, iron, cobalt, zinc, manganese, arsenic, and mercury, are abundantly disseminated through rocks of this class, in veins, beds, strings, or detached nodules ; and many primitive districts are charac- terized by the metalliferous deposits they contain. "Nothing can be more beautiful than the dru&y cavities met with in primitive mountains, whose walls are lined with pure and variously tinted and crystallized topaz, beryl, rock crystal, fluor spar, and calcareous spar; the gneiss, granite, and mica slate,with their imbedded crystals grains of sapphire, chrysolite, and garnet; and the veins in granite, clay slate, and other primitive rocks, with their emeralds, axinites and spinel rubies, afford to the mineralogist highly inte- resting combinations."* 30. Observations on the deposition of silica from the water of hot springs, together with the supposed impossibility of forming some mineral compounds by fire, induced the geologists of the school of Werner to ascribe the production of granitic rocks to water. But the discoveries of Sir James Hall and Mr. Gregory Watt, relative to the effect of gradual cooling on carbonate of lime and other bodies fused by heat, causing them to assume a crystalline structure, invalidated the arguments derived from the second consideration; and subsequent researches afford abundant evidence of the igneous origin of granitic rocks and their included minerals. 31. Mitscherlich found that the slags from iron smelting-fur- naces are often crystallized, have the form of augite, and agree with it in chemical composition. He, also, by exposing to intense heat the substances of which certain minerals consist, obtained crystals of those minerals; thus producing, artificially, amphibole, mica, and hyacinth. Berthier, likewise, formed silicates of manga- nese, as well as of iron, in his furnaces, and obtained them regularly In what rocks are the mineral repositories chiefly found ? Why was the origin of the primitive rocks referred, by the German geologists, to aqueous deposits? * Encyclopaedia of Geography, pt. ii. book ii. p. 220. SUBMEDIAL ROCKS. 409 crystallized.* Admitting 1 , then, that granitic rocks and those with which they are more- directly associated were formed by consolidation, after having been fused by heat, it must be manifest that if shells or other parts of living beings had entered into their composition, no traces of them would have remained, since, as to structure, at least, they must have undergone utter destruction. The primordial rocks, therefore, may be regarded as being dis- tinguished by the absence of organic remains and being the chief repositories of minerals. Submedial Rocks. 32. With respect to these rocks and the higher strata, our space will admit of only a few notices of the characteristic fossils of the several rocks or formations, with descriptions of some of the more curious and important. The submedial or transition rocks are not unfrequently so inter- mixed with the stratified primordial rocks, that it is difficult to discover the distinction between them.f Viewed on the large scale, they consist of "a stratified mass of arenaceous and slaty rocks, intermingled with patches of limestone, which are often continuous for considerable distances. The arenaceous and slate beds, considered generally, bear evident marks of mechanical origin, but that of the included limestones may be more question- able."^: By what experiments was its igneous origin rendered probable ? What materials, found in other formations, are wholly wanting in the primordial rocks ? What must have been the origin of beds of sand and slate ? * See Johnston on Chemistry, in Rep. of Brit. Assoc. 1832, p. 486 ; Cuvier Discours sur les Progres recens de la Chimie, pronounce en Mai, 182'5, dans une Seance des Quatre Academies; and Annales des Mines. t This difficulty is fully admitted by one of the latest writers 6n system- atic geognosy. "Some of the rocks constituting the primitive group are continued, and still more developed in the transition group; as the argil- laceous schists and calcareous rocks; and others, as the quartz and tho graywacke, are intimately connected with the primitive quartz and schists ; so that it might be supposed, that, from the lowest granites to the upper transition rocks, there was only one grand period." Trail '& de Geoynosie ; mis en Rapport avec VInlrod., pub. en 1828, par M. D'Anfiuisson de, Voisins. Pqr Amedie BuraL 1834. torn, i., p. 209. Hence M. Bnrat proposes a division of the transition rocks into two parts or classes. Mr. De la Beche remarks, that "towards the lower part of the grauwacke groupe its fossili- ferous character disappears, and the presence of crystalline rocks, appa- rently of contemporaneous origin, becomes more common. This change varies much in different countries ; but in general the slaty rocks gradually prevail, presenting a very great thickness of argillaceous schists. We seem to have arrived, in the descending order, at a state of the world when there was a combination of those causes which have produced fos siliferous and non-fbssiliferous rocks." Geol. Man., p. 422. \ De la Beche's Geol. Man. p. 414. 2M 410 ORYCTOLOGY. 33. It is in the calcareous rocks of this class chiefly that orga- nic remains are found ; for the gray wacke sandstones appear to contain none, and the transition slates relatively few. The vege- table fossils found in these rocks are seldom in such a state as to afford traces of their analogies with those of living plants. So far as can be determined from those which have been made out, it appears that the same kind of vegetation probably prevailed during the period in which these formations took place, as during the depositions of the carboniferous rocks. 34. As to the animal fossils, they are generally derived from the lower orders of beings, consisting principally of zoophytes, radiated animals, conchifers, molluscs, and crustaceous animals. A few ichthyolites have been found, indicating the existence of at least one genus, and two or three species of fishes. These rocks contain a mixture of genera of animals inhabiting the seas and oceans of the present day, and of others which are now not known ; but the species have all become extinct. 35. Among the more remarkable animal fossils are the trilobites, (see marginal figure,) long known in England under the appellation of " Dudley fossils," from their frequent oc- currence in the Dudley limestone. They are found so abundantly in the mountain lime- stone, in different parts of England, as to be characteristic of that formation. Specimens have also been discovered in Germany Sweden, and America. Another kind of trilobite (Asaphus debuchii} is so abundant in some parts of Wales, that the laminae slates are charged with them, and millions probably lived and died not far from the places where we now discover their remains. A great number of species of these fossils are found in the limestone beds at Trenton falls, New York, and other parts of the United States.* A variety of conjectures have been hazarded with regard to these extinct animals,f which ap- pear to have been Crustacea. What is the character of the fossils found in transition limestone? What orders of animals appear to have existed at the time the transition rocks were formed ? How are the fossil fishes of the transition group characterized, compared with recent genera and species? What class of fossils is found particularly abundant in the old transition limestone ? * See Dr. Jacob Green's Monograph of American Trilobites Also, the Transactions of the Geological Society of Pennsylvania, for a Description of some non-descript Trilobites, by Dr. Harlan. ED. t See Parkinson's Organic Remains, vol. iii. pp. 271. 275. PENTREMITES. 411 36. The crinoid animals constituted a once numerous class ot zoophytes, some genera and species of which have continued up to the present day ; while others, which are found in various rocks, have disappeared from among living animals. The lily encrinite (see preceding figure) belongs to the mountain limestone, and its remains form extensive strata of that rock, of which a representa- tion has been given in a preceding page. 37. In Lower Saxony and Westphalia, also, this stone is so abundant as to be used for building; and is composed, like the Derbyshire marble, chiefly of entrochal columns or stems of the encrinite ; but specimens of the body are very rare. These animals were composed of a multitude of small bones, forming a vertebral column, probably attached at its basis to the surface of rocks, and surmounted by a cup, from the edge of which proceeded digitated processes, the removal of the outer portions of which, in the preceding figure, shows the cluster of tentacula by which they were terminated. The whole skeleton must have been involved in a thick fleshy covering. Another highly interesting genus of fossils found in the transi- tion series, particularly the upper beds of that formation, is the pentremites,* first discovered and named by the late distinguished naturalist, Thomas Say, Esq. It is of a radiating or star-shaped figure, and appears to'have been fixed by the centre to an articu- lated column. In what rocks are crinoid fossils discovered ? In what manner were the encrinites constituted ? * See the Paper of Mr, Troost, in the Trans, of the Geol. Soc. of Penn. vol. i. p. 224. 412 ORYCTOLOGY 38. Among the corals are found some genera of which there are existing species. The annexed figure represents a madreporite. " It appears to have been imbedded in a hard, close-grained limestone, of a pale yellowish colour, part of which, containing fragments of shells and other marine remains, still ad- heres to the madreporite. The madreporite itself is formed of a spathose substance strongly impregnated with iron ; as is the case with all the fossil madrepores found at Steeple Ashton, the locality of this fossil."* 39. Notwithstanding there is a relatively small proportion of organic remains in the submedial rocks, it is evident that they must have been deposited when the atmosphere was adapted to the vegetation of plants, and when the sea was capable of affording habita- tion arid food for various kinds of animals ; and though no remains of terrestrial animals have been preserved, it is at least probable that such existed, for whom the vegetables served as food. Of the marine animals, vast multitudes have utterly perished, without leaving any traces be- hind. " Mere fleshy creatures may have existed in myriads, without any of them having been transmitted to us. In proof of this, if any were requisite, we may inquire what portion of those myriads of fleshy animals which now swarm in some seas, (as the medusae,) could be transmitted as organic remains to future ages."t Medial Rocks. 40. The formations of this class, constituting the "medial order" of Conybeare, are included among the floetz or flat rocks of Werner, and" by other geologists have been regarded as forming the lowest group of secondary rocks. They comprehend the principal deposits of coal, or great coal-fields; and hence the term carboniferous has been generally applied to them. The lowest of these rocks, termed the old red sandstone, contains but few or- ganic remains ; and so far as they have been observed, they ap- To what great division of fossils docs the madreporite belong? What must have been the condition of the atmosphere when the sub- medial rocks were forni.,J ? What classes of anime'.s have left no fossil remains? By what different na^v-s have the medial rocks been designated ? Which is the lowest of this group of formations? What term has been applied to the rocks of this class in consequence of their containing coal ? What organic remains are found in carboniferous sandstone? * Parkinson's Organic Remains, vol. ii. p. 67. t De la Beche's Geol. Man., p. 429. FORMATION OF COAL. 413 pear to be of a similar character with those in the strata im- mediately below or next above this sandstone. 41. The mountain limestone, also termed carboniferous lime- stone, presents considerable analogies with the transition lime- stone, relics of corals and radiated animals being inclosed in it, especially those of the encrinites. It is usually of a gray colour, and granular, but sometimes of a foliated texture, particularly where it comes, in contact with trap rocks. Some varieties are im- pregnated with bituminous or carbonaceous matter, and are of a black colour, as the marble called lucullite. Lead ore, and occa- sionally the ores of zinc and copper, occur in this rock, which has therefore been called metalliferous limestone. It seems to be the most recent formation in which metals are found in veins, which seldom rise into the coal strata; and when they do they soon ter- minate. 42. The coal-measures, as they are technically termed, including the associated beds of shale, clay, and ironstone, compose the highest formation of medial rocks ; though they are not exclu- sively confined to this series.* This valuable mineral is generally deposited in basin or trough-shaped hollows, of various extent, from one to many miles ; and it sometimes covers large areas, which may at a distant period have been deltas over which great rivers dispersed immense piles of vegetable matter, such as are now collecting at the mouth of the Mississippi. The manner in which coal and the alternating strata are usually disposed has been described already, and illustrated by a section of the coal-basin in the hill of St. Giles, near Liege. f In the great coal-field of South Wales the strata are arranged in a vast trough, over a tract nearly 100 miles in length, and from 5 to 20 in breadth. It contains twenty-three beds of workable coal, the thickest nine feet deep ; and in some parts there are sixteen seams or layers of ironstone.^: The coal fields of the United States extend through large portions of Pennsylvania, Ohio, Maryland, Virginia, Kentucky, Tennessee, Indiana, Illinois, Missouri, Alabama, and Arkansas, to points within 500 miles of the Rocky mountains. 43. Dr. Hutton ascribed the formation of coal to accumulations What ones in mountain limestone ? What are the chief varieties of this limestone ? Which is the highest formation of medial rocks ? In what manner are coal measures usually arranged ? What examples of accumulating vegetable matter may illustrate the probable mode of deposition in the coal beds ? * " Le carbone n'appartient pas exclusivement au terrain houiller. Nous avons vu former des amas et des couches exploitables dans le terrain de transition, et il se presentera encore dans des formations posterieures ; mais il y atteint son maximum d'abondance, et devient un caractere presque constant." Burat TraM de Geognosie, torn. i. p. 274. t See 387. t Bake well's Introd. to Geol., p. 152. 2 M 2 414 ORYCTOLOGY. of carbonaceous matter, from various sources, at the bottom of the sea ; but geologists at present seem to be generally disposed to regard this mineral as a deposit from fresh-water, consisting prin- cipally of vegetables, which became submerged in lakes, some- times occupying the spot on which they had grown, and into which descending torrents washed the clays and sands forming the beds interposed between the several strata of coal. These depositories, however, must have been occasionally overflowed by the sea ; for in some instances, beds of marine shells are found between those of coal. 44. That the coal strata have been partly formed by plants growing on the spot appears from the repeated examples which have been adduced of stems of trees found in coal mines, in a vertical position with their roots imbedded in the strata below. Mr. Witham mentions the occurrence of such stems in the Der- went mine, near Blanchford, Durham ; and of numbers of fossil vegetables, chiefly si.gi llarise, erect, with their roots imbedded in a small seam of coal under trie sandstone, and all truncated on the line of the high main coal bed, to the formation of which the tops probably contributed.* A curious instance of similar appearances is noticed by Mr. Wood, as having been observed at Killingworth colliery, in the same district. There were many fossil trees rising perpendicularly 10 feet through various strata of shale and sandstone. They were filled with sand, resembling that of the upper beds ; so that they must have been hollow when those beds were deposited. f 45. Mr. Witham, in a subsequent publication to that just quoted, has given an account of some interesting researches concerning the structure of fossil plants found in the carboniferous strata. In the neighbourhood of Coldstream, on the banks of the Tweed, numerous fossil vegetables occur imbedded in shale, be- longing to the carboniferous group. Stems of trees are found contorted and flattened, as if they had been subjected to extreme pressure. The longest stem obtained was not much more than 4 feet, and the lowest part of it about 6 feet in circumference. 46. " In 1820 an enormous trunk was exposed in the lowest bed of Craigleith quarry, near Edinburgh, at the depth of up- wards of 130 feet. The length of this trunk was 36 feet, and its diameter at the base 3 feet. It lay in a nearly horizontal position, corresponding with that of the stratum of hard white sandstone in which it was imbedded. It was incased in a layer of coaly mat- What account did Hutton give of these beds ? How do modern geologists regard them ? What facts prove that the vegetables contributing to the coal beds sometimes grew on the spots where they now repose ? Into what form is the cross section of imbedded trees found to be changed? * Observations on Fossil Vegetables. 1831. p. 7. t De la Beche, from Trans, of Society of Natural History of Newcastle, vol. j. ; and Lindley and Hutton's Fossil Flora of Great Britain. FOSSIL STEMS OF TREES. 415 ter, being probably the altered remains of the bark." From analysis it was found to be composed of carbonate of lime, 60 parts; oxide of iron, 18; alumine, 10; and carbonaceous matter, 9. Its interior structure resembled that of the coniferae. 47. " In November, 1830, a magnificent fossil stem was dis- covered in tbe same quarry, which, in geological position, is situated in the mountain limestone group, and lies considerably below the great coal basins of the Lothians." It. 48. "The length of the stem, (see preceding figure,) from the base to the top, was 47 ft. It presented the appearance of a large branchless trunk, in some parts greatly flattened, so as to form an elliptical section." Dimensions: A, diameter, 5 ft. by 2 ft.; B, C, 2 ft. 8 in. by 1 ft. 5 in. ; D, E, 2 ft. 7 in. by 1 ft. ; F, 1 ft. 10 in. What was the composition of the fossil tree found at Craigleith quarry? 416 ORYCTOLOGY. by 1 ft. 3 in. ; G, 1 ft. 7 in. by 1 ft. 4 in. ; H, supposed prolonga- tion of the top of the stem, 12 ft. ; I, upper part of the tree first discovered, showing a cavity, the seat of a branch. The superin- cumbent mass must have been above 100 feet in depth. The bark was converted into coal. This fossil also exhibits the usual struc- ture of the coniferae, and appears from analysis to have consisted of carb. of lime, 62; carb. of iron, 33; carbon, 5. : sp. gr., 2.87. 49. A third fossil stem of a similar character was found in 1831, in the same quarry.* Messrs. Lindley and Hutton, in their " Fossil Flora," vol. i. p. 9, pi. ii., have described the trunk of 1826 and that of 1830, under the appellation of Pinites withami , ard_ have named that of 1831, Pinites medullaris. Some remarkable vegetable fossils have been obtained from the Northumbrian coal mines ; one of which is shown in the preceding figure. The specimens " consist of sub-cylindrical or % slightly-com- pressed dichotomous stems. The surface is covered by a thick envelope of carbonaceous matter, presenting indistinct protube- rances arranged in spiral series, and beneath which are observed papillae of an elliptical form, higher than broad. The above figure represents a portion of one of the stems, denuded of its carbona- ceous covering."]- What were the dimensions of the largest specimen found at the same place ? How many per cent, of carbon were found in its composition ? What is the exterior appearance of the fossil stems found at the Northumbrian coal mines. * Witham's Illustrations of Fossil Vegetables, sect. iii. t Witham's Illustrations, p. 52. STRUCTURE OF RECENT LYCOPODIUM. 417 50. The marginal figure exhibits a longitudinal section of a part of one of These fossils, in which the central axis or pith is entirely filled by cal- careous spar, and a tube of carbona- ceous matter. From the axis emanate, on all sides, cylindrical processes, consisting of cellular tissue, with central fasciculi of vessels. They proceed obliquely upwards and outwards, and terminate in the papillary eminence on the surface of the stem.* 51. These processes are seen cut obliquely in the foregoing figure, representing a transverse section of the stem, the processes appearing as white oblong markings dispersed in the brown pa- renchymatous tissue. f The planfr evidently belongs to the vas- cular cryptogamic class, and appears to be allied to the lycopodia. What materials are found in the interior of the mass ? To what class of vegetables have those stems been supposed to belong ? Why? Witham's Illustrations, p. 52. t Idem, r. 53. 418 ORYCTOLOGY. 52. The preceding figure represents a tranverse section of the Lycopodium clavatum, exhibiting the same kind of cellular struc- ture and central axis, as appears in the fossil stem. An oblique section of a process of the Lycopodium clavatum, showing the structure of the tissue, of which there are traces in the fossil.* 53. To the plant which produced the Northumbrian fossils, Mr. Witham has assigned the name of Lepidodendron harcourtii. He has examined and described the structure of fossil plants belong- ing to four distinct genera : Pinites, pitus, anabathra, and lepi- dodendron ; including nine species. From the sections of fossil stems found in the coal strata and mountain limestone, he infers that " these combustible beds were masses of vascular and cel- lular cryptogamic plants, mixed with gymnospermous phane- rogamic trees, or others of a closely-allied structure ;" and not entirely of vascular cryptogamic vegetables, as some have sup- posed. f 54. Branches and leaves of plants, especially of ferns, are abun- dant in the coal-measures and the formations with which they are connected. Numerous specimens are preserved in various cabi- nets of natural history ; two of which are exhibited in the follow- ing figures. What appellation has been applied to the fossil form of the Northum- brian locality ? What mixture of plants was probably once found in the region to which they belonged ? What classes of plants are particularly abundant in coal beds ? * Besides the preceding, Mr. Witham bas given several other interesting magnified sections of different parts of these fossils, t Illustrations, sect. i. p. 10. LIAS AND OOLITE. 419 Super-medial Rocks. 55. The penean or lower group of these rocks consists partly of new red sandstone, with beds of marl, and also gypsum and rock salt ; and in the bituminous copper slates are found the first traces of those immense reptiles of the lizard family, which are so abundant intheliasic group. The zechstein or magnesian lime- stone contains only a few genera of plants, several of shells, mol- lusca, radiaria, and zoophytes, three of fishes, and one reptile. 56. In the keupric group occurs a greater variety of plants and animals, including among the latter five or six genera of saurian rep- tiles. Among the organic remains of the muschelkalk, two of the most characteristic are perhaps the Ammonites nodosus, and the Encrinites moniliformis, or lily encrinite ; but the former is also found in the higher, and the latter in the inferior rocks. Among the red marls and sandstones by which the shell limestone is some- times replaced, are likewise beds of rock salt; and from the pre- sence of that useful mineral in this and the preceding group, they have been described together by some geologists, under the appel- lation of the " Saliferous System."* 57. The formations* which constitute the two following groups, (the liasic and the oolitic,) are peculiary rich in fossil remains. Among those of vegetable origin are lignites, fossil wood, some- times siliceous impressions and casts of fern, (see p. 403,) cyca- daceae, and fuci. But these are not the only kinds of plants. Mr. Wit-ham found in these groups three species of a genus named pence, peculiar to the lias and oolite, or at least not occuring in anterior deposits ; and two species of pitus, which also appear in the mountain limestone. From an examination of these fossil trees, he asertained that their tissue, in tranverse sections, corresponds precisely with that of our coniferae, and more especially with that of the genus pinus. 58. From the circumstance that the concentric layers or the fos- sil vegetables, which Mr. Witham has described as occuring in the lias and oolite of England being like those of recent trees, some much broader than others, he infers, that the climate which existed at the epochs when these vegetables grew, re- sembled that of the same country at the present day, in the irregularity of its successive summers. " The coniferae of the coal formation and mountain limestone group have few and slight appearances of the lines by which the annual layers are separated ; which is also frequently the case with the trees of our present What constitute the lower part of the supermedial rocks ? What animals are found in the lower members of this series of rocks ? What class of rocks constitute the saliferous system ? What vegetable organic remains are found among the lias and the ooli- tic group ? To what classes do the fossil trees of this group belong ? * See Encyclopaedia Metrop. Mixed Sciences, vol. iv. p. 608. 420 ORYCTOLOGY. tropical regions. It is therefore possible, that at the epochs of these formations, the changes of season, as to temperature, at least, were not abrupt."* Hence it may be concluded, that the climate of these latitudes, which resembled that of tropical countries when the vegetables forming the coal strata flourished, had become more temperate and variable during the growth of the plants im- bedded in the liasic formations. 59. But the groups now under consideration are most remarka- ble on account of their animal fossils, which are numerous and interesting. In the lias the crinoid radiaria again make their ap- pearance. The Briarean pentacrinite is one of those animals the remains of which are most common in England. The preceding figure exhibits part of the vertebral column, and articulated processes connected with it. These fossilized animals were akin to the encrinites, from which they are characteristically distinguished by the shape of the bones composing the spinal columns. In the encrinites they are circular disks, as may be perceived by turning to the figure, p. 411, in which several of these bones are shown imbedded in mountain limestone. The bones of the pentacrinite What inference has been drawn from an inspection of foesil vegetables ? What changes of climate, in the temperate zones, appears to have taken place during the period from the deposition of the coal strata to that of the lias groups ? For what class of fossils are these groups most remarkable ? * Illustrations of Fossil Vegetables, p. 58. ICHTHYOSAURUS. 421 are pentangular. Multitudes of them are found detached in the formations of the liasic and oolitic groups, and in the higher strata; from their figure they have been named astroites or star-stones ; and they are so often met with at Lassington hill, near Gloucester, England, that they have obtained the provincial appellation of " Las- sington stones." 60. The pentacrinite is one of those fos- sil animals, of which there are probably liv- ing analogues. The marginal figure repre- sents the upper portion of a radiated animal, described by M. Guettard, from a specimen obtained at Martinique.* A pentacrinus, differing from the preceding, is also said to have been recently discovered in the West Indies; and a smaller species more lately in the cove of Cork.f 61. But among the singular organic re- mains derived from animals which occur in *these groups, the gigantic and monstrous lacertae deserve particular notice. Some of these inhabited the waters; and others flit- ted through the air like birds, or rather bats. 62. The ichthyosaurus, so called from its partly resembling a fish and partly a lizard,^ had a head like the latter, terminating anteriorly in a long pointed muzzle, armed with numerous coni- cal teeth. It had a long tail, capable of extensive vibratory motion; and its extremities were furnished with paddles of a peculiar construction, (see subsequent figure of the plesiosaurus.) 63. The succeeding figure represents a part of the head of the Ichthyosaurus latifrons. The socket of the eye measures about 9 inches across, whence an idea may be formed of the enor- mous size of the animal to which this head belonged. The Ichthyosaurus communis sometimes exceeded 20 feet in length ; the I. platyodon appears to have had jaws 8 feet in length ; and the /. immanis was a gigantic species of which several bones belonging to the different parts of the skeleton have been pre- served by British geologists. In what respects do the pentacrinites of this series differ from the en- crinites of the lower groups of rocks? By what local name has this fossil been distinguished in England ? What were the peculiarities of form in the fish lizard ? What was the size of its eye? * V. Mem. de 1'Acad. des Sciences de Pann. 1755. t Bakewell's Introd. to Geology Prelim. Obs., p. 35. Mr. Bakewell has given a representation of the latter pentacrinus, from a drawing by Mr. J. V. Thompson, of Cork. J From the Greek VCQvs, a /*. an d Eavpos r a lizard. 2N ORYCTOLOGY. 64. The plesiosauri constituted another genus of these strange swimming lizards. Its limbs have analogies with those of the foregoing animal : but more elongated and flexible. What, how- ever, especially distinguishes it from all oviparous and viviparous fjuadrupeds, is a slender neck, as long as its body, composed of thirty or more vertebrae. An idea of its general form may be obtained from the following figure, representing the Plesiosaurus dolichoddrus. " If any thing," observes C u vier, " could j ustify those hydras and other monsters, the figures of which are so often presented in the monuments of the middle ages, it would incontestably be this plesiosaurus."* 65. A more grotesque and monstrous animal than either of the What circumstance distinguishes the plesiosaurus from all the known quadrupeds ? * Theory of the Earth, p. 257. For descriptions and figures of various species of ichthyosauri and plesiosauri, see Cuvier Recherches sur les CJpsemens Fossiles. torn. v. pt, ii. HYL.KOSAURUS. 423 preceding, is exhibited in the annexed figure of the fossil skeleton .^,of a pterodactyle. or flyino- lizard. ,.-.,., "'"'"I TL. f -i I Lhese fossils are not very common: HHHHH they are found in the limestone slates fflof the liasic group, at Solenhofen, in Hi|i Germany ; at Stonesfield, in Oxford- ire, and at Lyme Regis, in Dorset- H shire. One species was about the size of a thrush, another of that of a com- mon bat; and the remains have been discovered of some of larger dimensions.* 66. The wealden group is not less remarkable than the pre- ceding, for its fossil remains. Among those of vegetable origin may be mentioned the silicified trunks of coniferous trees, and plants allied to the recent genera cycas, and za/ma, which have been found in a stratum called the dirt-bed, in the Isle of Portland. Many of the stems are still erect, as if petrified while growing undisturbed in their native forest. f 67. But the animal fossils discovered by Mr. Mantell among the strata of Tilgate forest, in the weald of Sussex, are more curious and interesting. Besides relics of crustaceous and testa- ceous animals and fishes, he has been enabled to recognise those of immense saurian reptiles, some of which were before unknown. To one of these animals he gave the appellation of iguanodon, from its affinity to the iguana. From the form of its teeth it ap- pears to have been herbivorous; and a comparison of its bones with those of the recent iguana, led to the conclusion, that it must have been fourteen times as large, or not less than 70 feet in length. 68. In the summer of 1832, workmen employed in quarrying the Tilgate grit, found a hard block, in which were embedded a number of fossil bones. These being examined by Mr. Mantell, were ascertained to have belonged to a new saurian animal, which he described in a paper read before the Geological Society, and afterwards published. He gave to this creature the name of lltjkfosaurus, or wealden lizard. It must have been from 20 to 30 feet in length, and appears to have resembled the recent Iguana cornuta, in being armed with a horn on the forehead, and .a row In what localities has the pterodactyle been found ? AVhat was the size of this animal ? What are some of the vegetable fossils of the wealden group of rocks ? To what geologist do we owe the discovery of animal fossils in that group? What important additions have been made to the list of saurian animals by Mantell ? * V. Cuvier Recherches, u. a. t See Mantell's Geology of the South-East of England, chap, xi, J Idem, pp. 304316, 424 ORYCTOLOGY. of spines along the back : it had an immensely long tail, and its body was covered with scales ; whence it has been proposed to call it Hylaeosaurus armatus.* 69. In the formation of the cretaceous group are abundance of organic remains of vegetables and animals. Besides numerous shells, and relics of radiated animals, molluscs, and Crustacea, there are in these strata some curious zoophytes. Among the fos- sils that may be regarded as characteristic of this group, may be mentioned, alcyonites, echinites, ammonites, and belemnites. 70. The marginal figure repre- sents a fig-formed alcyonite, of a dark red colour, where the surface is not concealed by its cortical coat, which is gray, pervaded by a slight tinge of red. "The pedicle and the opening at the superior part are here very perfect. Slight traces of lines, passing from the pedicle to the opening, are discoverable in this specimen, and doubtless point out the arrange- ment of fibres by which the animal was enabled to draw in and eject the water which supplied it with food."f " The recent ani- mal, according to Count Marsigli, is of the form of a fig, being at- tached to the rocks by branches proceeding from its smaller end; its upper part being a little flattened, with a hole in the centre. Its colour resembles that of tobacco ; and its parenchymatous substance, he thinks, cannot be compared to any thing better than to nut-galls, when well dried." 71. An echinite from the Kent- ish chalk pits, with one of its spines, is exhibited in the annexed figure. Various species of the genera echinus and cidaris are found fossilized in Wiltshire, and other southern counties of Eng- land, where the black flint most abounds. These animals, some- times called sea-eggs, are common in a recent state. What variety of organic remains has been discovered in the cretaceous group? What is the structure of the fig alcyonite ? What is the appearance of the recent specimen of this zoophyte? * See Geology of the South-East of England, pp. 316328, * Parkinson's Organic Remains, vol. ii. pp. 96, 97. ANTHOPHYLLUM ATLANTICUM. 425 The accompanying figure is a representation of the Plagiostoma dumosum, found by Mr. T. A. Conrad, in a bluff of nummulite limestone, at St. Stephens, on the Tombeckbe, Alabama. It was taken from near low water mark, where the bluff was 100 feet high, composed throughout of different classes of shells, connected together by the lime.* The Anfhophyllum atlanticum, de- scribed by Dr, Morton, in the Journal of the Academy of Natural Sciences of Philadelphia, is represented in the annexed figure, It is a species of fos- sil polypus, found abundantly in the limestone of Gloucester county, New Jersey. 72. Two genera of saurian reptiles in the fossil state occur in the creta- ceous rocks. These consist of a species of crocodile, found at Meudon, in France; and the Moso- saurus, remains of which were first discovered in the quarries of St. Peter's mountain, near Maestricht; and since near Lewes, in Sus- sex. This creature appears to have been nearly 24 feet in length.* Describe the fossil polypus found in the American cretaceous group? Where was the mososaurus first discovered ? * See Morton's Organic Remains, p. 60. t See Mantell's Geology of the South-East of England, pp. 146152 ; and Cuvier Recherches, torn. v. pt. 4. 2N-2 126 ORYCTOLOGY. The preceding figure exhibits a representation of a fragment ot the lower jaw of this saurian monster, preserved in the British Museum. 73. The fossil remains of the unparalleled saurian animal, described by Dr. Harlan, under the name of basilosaurus, were first made known by Judge Bree, who transmitted to Philadelphia a vertebra, found in the marly banks of the Washita river, in Arkansas territory, taken from a skeleton said to be 150 feet long. In the course of the year 1835, there have been obtained from a lime- stone rock, 30 miles north-west of Claiborne, Alabama, several bones of the same extinct race.* The skeleton was, at the early settle- ment of that state, exposed to view on the surface of the rock, for much more than 100 feet in length. These bones have been entirely converted into limestone, not a particle of animal matter remaining ; for when tested with muriatic acid the whole substance is dissolved, and nothing but muriate of lime is obtained. Tertiary Rocks. 74. In the formations above the chalk, the organic remains in crease in number and variety ; though many fossils found in the lower series no longer occur. Only a few of the most remarkable can be noticed here. Extensive catalogues of shells, distinguish- ing their localities, their living analogues where they are known, and the relative ages of the deposits in which they are found, have been published by M. Deshayes and Mr. Lyell.f The Cerithium giganteunij which is remarkable for its size, is found in the Lon- don and Paris basins. 75. The most extraordinary shell of this genus f Cm'Mmm) is C. giganteum. It is turreted, extremely long, and transversely striated : the turns in their upper part are tubecular, and the Where the basilosaurus ? What is supposed to have been the length of the latter animal ? What circumstances distinguish the Cerithium giganteum ? * For a full account of these fossils see the first volume of the Transac- tions of the Geological Society of Pennsylvania, p. 348. For the accuracy of the description and of the drawing of Mr. R. C. Taylor accompanying them, we can fully avouch, having seen the bones at the time of their re- ception. ED. t Deshayes Description des Coquilles caracteristiques des Terrains Paris, 1831. Lyell's Principles of Geology, vol. Hi. 8vo. 1st edit- PAL^OTHERIA. 427 columella has one fold. These enormous shells are generally a foot in length. One of the specimens which I possess, and which has lost at least an inch or two of its length, still measures 14 inches. They are found at Grignon, and are not very rare : they are, however, in general, very much injured ; very seldom indeed having the lip and sides open and perfect. Their form is that of a winaing turriculated pyramid, with, in general, twenty turns, heset on their upper part with a row of nodular tubercles, and having the general surface lightly and transversely striated. The opening is oblong and oblique, and terminates in the lower part in a canal, the extremity of which is moderately recurved ; and the superior part, instead of forming a canal, is laterally extended, in the manner of an ear-like process. There is only one fold on the columella. This is, undoubtedly, the largest unilocular univalve shell that is known."* 76. During the long period of the deposition of the tertiary for- mations, quadrupeds existed ; several of which, now extinct, dis- play peculiarities of form and structure. To the researches of Cuvier we are indebted for the discovery of the genera of the palseotheria, lophiodonta, anoplotheria, anthracotheria, chseropotami, and adapis. The marginal figure represents a lower jaw of the Palaeotherium maximum of Cuvier. 77. "The palaeotheria must have resembled the tapirs, among recent animals, in their general form, and in that of the head, par- ticularly in the shortness of the bones of the nose, which announces that they must have had a small proboscis like the tapirs, and lastly, in their having six incisors and two canine teeth in each jaw; but they resembled the rhinoceros in their grinders, (of which those of the upper jaw were square, with prominent ridges of various configuration, and those of the lower jaw in the form of double crescents,) as well as in their feet ; all of which were divided into three toes, while in the tapirs the fore feet have four. It is one of the most extensively-diffused genera, and most numerous species that occur in the deposits of this period."f The bones of these extinct quadrupeds are found in the gypsum quar- ries of Paris, and in other parts of France. 78. Among the fossils of the British Museum are the lower jaws What classes of quadrupeds have been discovered by Cuvier in the ter- tiary strata ? To what class of recent animals has the palaeotherium been assimilated ? In what respects did it resemble the tapirs? In what localities has the palseotherium been obtained ? * Parkinson's Organic Remains, vol. iii. p. 71. t Cuvier's Theory of the Earth, p. 266. See also Recherches, torn. iii. and torn. v. pt. ii 428 ORYCTOLOGY. of different species of deinotheria, part of an upper jaw, and de tached teeth ; from Eppelsheim, in Germany. The above figure exhibits a lower jaw of the Deinotherlu^ g'gantetui some of the teeth of which are wanting ; but in which is seen one of the very singularly-formed tusks, or weapons with which nature had armed this quadruped. Alluvial Deposits and Bone Caverns. 79. The remains of several animals no longer in existence, mingled with those of living species, occur in the relatively recent formations. Among these, the Mastodon ohioticus has attracted particular attention. The earliest notice that occurs of this animal is in a letter from Dr. Mather, of Boston, to Dr. Woodward ;* and in 1740, relics of the mastodon were found in Kentucky, on the banks of the Ohio. Immense quantities of its bones have since been discovered in America. The marginal figure is a representation of a lower jaw of the M. ohioticus. It measures about three feet along the base. 80. Cuvier says, the great mastodon was as high in proportion as the elephant, with equally long tusks,and had grind- ers covered with bristling points, which made them long be considered as What constitutes a distinguishing peculiarity of the deinotherium ? To wkal class of quadrupeds did the Mastodon ohioticus, belong? See Philos. Trans., abridged by Jones, vol. v. pt^ ii. p. 159. MEGATHERIUM. 429 those of a carnivorous animal. Its bones were extremely large and solid. Its hoofs and stomach are said to have been found in such a state of preservation as to be recognisable ; and it is as- serted, that the stomach was filled with bruised branches of trees. The Indians imagine that the whole race was destroyed by the gods to prevent them from destroying the human species. This seems to be a proof that the mastodon was extinct before America was inhabited by man; or else the Indians could not have mis- taken this phytovorous quadruped for a beast of prey.* 81. The fossil elephant, called by the Russians the mammoth, was another of the ancient pachydermata, thousands of the car- cases of which were dispersed over the surface of the earth, from Spain to the shores of Siberia, and throughout North America. It was one of this species that was found in the beginning of the pre- sent century, at the mouth of the river Lena, preserved in ice, and of which the skeleton was removed to St. Petersburg. This animal differed from the modern elephants, in having a thick coat of long hair on its body : it was more than 9 feet high, and 16 in length, f 82. To this period has been assigned the Megalonyx jeffersonil^ a quadruped whose bones have been found in the western part of Virginia, in a cave in the county of Green Briar, three feet be- neath the surface of the ground, and also in Big Bone cave on the line dividing White and Warren counties, Tennessee.^: This crea- ture, from its teeth and claws, appears to have resembled the sloth and anteaters ; but in size it must have equalled the largest oxen. 83. The megatherium, the relics of which have been discovered in South America, exhibits an union of the characteristics of the armadillos and the sloths, with the magnitude of the rhinoceros. Its claws must have been of a monstrous length, and prodigiously strong ; and its whole frame displays excessive solidity. A ske- leton of this animal, found at Beunos Ayres, was sent to Madrid in 1789 ; and one more recently discovered in Paraguay, was con- What superstition have the Indians in regard to the mastodon ? What light does their belief throw upon the period when the mammoth became extinct? What peculiarity distinguished the fossil elephant from the existing species ? Where are the fossil specimens to be found ? v ln what localities has the megalonyx been discovered ? Where did the megatherium exist? * V. Recherches sur les Oss. Foss., torn. i. and torn. iii. t See Mr. Brande's Journal of Science, vol. viii. p. 96 ; and Cuvier Re- cherches, torn, i., iii. The soft parts of this animal had been so completely protected from decomposition, during a long series of ages, by the frozen matter in which it was enveloped, that the flesh was devoured by bears and other beasts of prey, after its release from its icy sepulchre. \ See Dr. Troost's Paper in the Transactions of the Geol. Soc. of Penn- sylvania, vol. i. p. 236. ED. 430 ORYCTOLO^Y. veyed to England by Mr. Woodbine Parish, and presented to the Royal College of Surgeons, in London.* 84. Contemporary with these and other animals, the genera of which are become extinct, were hyenas, bears, tigers, wolves, and other beasts of prey, differing only in species from those now existing. At this epoch, remarks Cuvier, " the class of carnivora was numerous and powerful." The palaeotheria, and other mam- malia and reptiles of the tertiary period, having been destroyed by some convulsions of nature, were replaced by a brute population of a different character, and these in their turn were extirpated by an overwhelming catastrophe, which must have preceded the ori- gin of the human race. 85. The bone caverns, with their contents, and the osseous breccia found in other situations, present phenomena connected chiefly with the geological formations posterior to those of the tertiary period. Caves containing the bones of bears and other ani- mals have been long since noticed in Germany. The most anciently celebrated is Baumanshole, in the county of Blankenberg, described by many authors, especially by Leibnitz, in his " Protogaea." It is formed of several caverns, containing abundance of stalactites and the bones of animals, principally bears. The caves of Gaylen- reuth, in Franconia, and Adelsberg, in Carniola, have also attracted much attention ; and there are many others, but it does not appear that among the bones found in them there were any of animals be- longing to the lost genera.f 86. In England several bone caverns have been observed ; as that of Kirkdale, in Yorkshire, discovered in 1821, and examined a few months afterwards by Professor Buckland. The floor of this cave was formed of argillaceous and slightly micaceous loam, mixed with much calcareous matter, and coated with stalagmite ; beneath which were buried bones and teeth of the hyena, tiger, bear, wolf, fox, weasel, elephant, rhinoceros, hippopotamus, horse, hare, rabbit, water-rat, and mouse ; raven, pigeon, lark, a small kind of duck, and a bird about the size of a thrush. From the manner in which these relics were dispersed over the bottom of the cavern under the mud deposit, and the great preponderance of hyenas' teeth among the bony fragments, Dr. Buckland con- cluded that this place had been a den of hyenas, at a remote period, What genera of existing quadrupeds were found at the period when the tertiary rocks were deposited ? How near is man placed, in the succession of races, to those of the ter- tiary period ? To w hat geological period do the bone caverns belong ? In what country were they first observed? What particular animal is found in the German bone caves ? What variety of bones were found in the Kirkdale cavern? * For an account of the megalonyx and megatherium, see Cuvier Re- cherches, torn. v. pt. i. t See Prof. Jamoson's Geological Illustrations of Cuvier's Theory of the Earth. Note on Caves containing Bones of Carnivorous Animals. BRECCIAS. 431 when tigers, elephants, and hippopotami, were among the brute population of that part of the surface of the globe ; that the hyenas had brought in the bones of other animals which they made their prey ; and that this state of things was suddenly ter- minated by an irruption of a diluvial torrent, which buried the drowned and previously destroyed animals in an envelope of mud.* 87. There are also ossiferous caverns in France, which have excited particular attention -on account of the occurrence of human bones in them, together with those of other animals. In the ca- vern of Bize, in the department of Aude, M. Marcel de Serres met with a small number of human bones, mixed with those of extinct animals and with land-shells, in a calcareous, stony mass, ce- mented by stalagmite. M. Tournal also found in this mass and the black mud above it, human teeth, and the fragments of rude pottery, f 88. In caverns in tertiary limestone, at Poudres and Souvenargues, in the department of Herault, and in a cavern near Miallet, in the department of Gard, human bones and coarse pottery have been discovered, mingled with the relics of lost animals.:}: These phe- nomena gave rise to a controversy as to the probability of man having been contemporary with the brutes with whose remains his own are now intermixed. After noticing the arguments on both sides, Mr. Lyell observes, that " as many of these caverns may have served in succession as temples and habitations, as places of sepulture, concealment, or defence, it is easy to conceive that human bones, and those of other animals in osseous breccias of much older date, may have been swept away together by inun- dations, and then buried in one promiscuous heap. It is not on the evidence of such intermixtures that we ought readily to admit either the high antiquity of the human race, or the recent date of certain lost species of quadrupeds. " 89. Osseous breccias are not confined to caverns. They occur frequently in places on the northern shores of the Mediterranean and its islands. At Cagliari, Sardinia, such breccia is found in the clefts and small caverns of a tertiary rock, about 150 feet above the level of the sea. Dr. Christie describes such a deposit at San Giro, near Palermo, as not being confined to the cave itself, but as forming part of the external talus, resting upon the upper tertiary What circumstance gives particular interest to the bone caves of France ? What question has been raised respecting the relative times at which the several kinds of bones were deposited ? What inference has Lyell formed respecting this subject ? In what situations are bone breccias found ? * See Buckland Reliquiae Diluvianae. t M. de Serres Geognosie des Terrains Tertiaires ; ou Tableau dea Principaux Animaux invertebres des Terrains marins tertiaires du Midi de la France. 1829. t Bulletin de la Societe Geologique de France, torn. ii. $ Principles of Geology, vol. iii. p. 165. 432 ORYCTOLOGY. beds, with a thickness of about 20 feet, The bones were those of the elephant, hippopotamus, deer, and of the dog. At Gibraltar have been observed breccias, formed by the bones of small animals, which seem to have been thrown down from the nests of hawks, which build in fissures of the rock. They are cemented together with fragments of decomposing limestone by ferruginous matter. In New South Wales, osseous breccias have been found, including the bones of animals now known to exist in that country. 90. When the bones of elephants and other large quadrupeds were found imbedded in the earth in the middle ages, it was conceived by the credulous naturalists of that time that these were human relics. In 1577, Felix Plater, professor of anatomy at Basle, described seve- ral fossil bones of the elephant, found at Lucerne, as those of a giant at least 19 feet high. Some immense bones having been discovered in 1613, near the castle of Chaumont, in France, a sur- geon of Beaurepaire, named Mazurier, procured them, and made a public and no doubt a profitable exhibition of them, as the re- mains of a gigantic king of the ancient Gauls, pretending that they had been inclosed in a sepulchre 30 feet in length, bearing the inscription, " TEUTOBOCHUS REX." The bones, however, were those of an elephant. 91. At a subsequent period, Scheuchzer, a Swiss philosopher, brought forward an example of a skeleton of more moderate dimen- sions, imbedded in hard stone, which he represented as the undoubted relics of a human antediluvian. He published an abridged account of this wonderful fossil, in the Philosophical Transactions, 1726 ; and he made it the subject of a distinct trea- tise, entitled "Homo testis Diluvii." Cuvier, at length, ascer- tained that this alleged anthropolite (the nature of which had been questioned by Camper and others) was a petrified lizard, a large extinct species of salamander.* 92. There is, however, at the British Museum, in London, a genuine anthropolite, from Guadeloupe, in the West Indies. It consists of a considerable portion of the skeleton of a woman (the spine, pelvis, several ribs, one arm, the leg and thigh bones) im- bedded in a block of calcareous stone. The stone is a kind of travertin, formed of land-shells, slate, and fragments of shells and corals from the sea ; which, like rocks of a similar composition found elsewhere, has acquired a great degree of hardness. It is consequently a recent petrifaction in an alluvial formation. f Other skeletons, probably those of Caraibs, are contained in the same calcareous rock ; and one, with a portion of the head re- maining, is preserved in the Museum of Natural History at Paris. What was formerly thought of the bones found in caverns by the early naturalists ? What impositions were practised upon the credulit What did Cuvier find to be the true character of Scheuchzer's supposed anthropolite ? In what formation have true human skeletons been found ? * Bertrand Lett, sur les Rev. du Globe, lett. ix. xvi. t Jameson's Illustr. of Cuvier, pp. 406410. ORGANIC REMAINS. 433 93. In the course of geological inquiries in the United States, abundant evidence has already been furnished that the organic remains imbedded in the rocky strata of America, are on a scnle, both in point of abundance and magnitude, corresponding with the grandeur of her natural scenery her mountains, lakes, rivers, forests, and prairies. We need not mention more than the Mega- lonyx jt'Jftrsonii, the gigantic mastodon, the megatherium of Cuvier, and the basdosaurus of Dr. Harlan, to make apparent the justness of the preceding remark. 94. The eastern part of the United States being a primordial region, affords comparatively few organic remains ; but the mid- dle, southern, and western states, both east and west of the Mis- sissippi, are characterized by vast numbers of shells, bones, casts of mollusci, trees, and plants, including multitudes not known to exist at present in any part of the continent. The cretaceous group, in particular, has afforded already a rich harvest to the labours of American oryctologists, and as other parts of the geolo- gical series become better known, there cannot be a doubt that the more ancient inhabitants of the planet will be found in America, in as great abundance as in any other region of the earth hitherto explored. 95. The group just mentioned has been traced through New Jersey, Delaware, Maryland. Virginia, North Carolina, South Carolina, Georgia, Alabama, Mississippi, Tennessee, Louisiana, Arkansas, and Missouri.* "In fact," says Dr. Morton, "a great part of the level country between the Rocky mountains and the Mississippi, is occupied by this formation ; and I have also seen some fossils from thence which bear a strong affinity to those of the lias of Europe." 96. The evidence of identity in the strata thus observed, at points scattered over a space more than three thousand miles in extent, rests not only on the general resemblance of the mineral sub- stances composing the strata, but more especially on the generic and specific accordances in the fossil shells, which are found in every part of this vast extent of country. "Thus," says the author just cited, "the Ammonites placenta, Bacculites ovatus, Gryphaeavomer, Gryphaea mutabilis, Ostraea falcata, &c.,are found, without a shadow of difference, from New Jersey to Louisiana." 97. To the study of this and various other strata containing organic remains, the geologists of America are now applying themselves with an ardour which has derived fresh impulses from every new reward of their labours. The hope of being able to decide, by this kind of observation and comparison of animal remains, the great question in regard to the relative time of deposition of the several What is the relative importance of American fossils when compared with those of other countries ? In what part of the United States do the primordial strata prevail ? What is the extent of the cretaceous group of North America ? See Morton's Organic Remains, pp. 14 25. 2O 434 ORYCTOLOGY. rocky strata, is with them much enhanced by a circumstance early noticed by William Maclure, Esq.,* who has, with justice, been denominated the father of American geology. His extensive travels, on both the European and the American sides of the At- lantic, had enabled him to compare " the vast confusion and intri- cacy of the stratification of the old continent, by which different classes of rocks are mixed and thrown out of their natural posi- tions, with the fortunate regularity of the geology of our continent, and the ease with which the science may be studied, from the well defined boundaries which nature has given to the different classes of rocks running in the same direction from one end of the continent to the other ; having the line of separation so distinct between the different rocks in the limits of each class, as to reduce to a certainty the place that each occupies in the natural order." 98. " This results from the fine opportunities afforded of examin- ing the line of separation at every junction, through a distance of twelve or fifteen hundred miles, by which means any observer can obtain a more accurate knowledge of geology in one year, in the United States, than he could in a long life spent in travelling in any other part of the globe hitherto examined and described.^" What character in the American strata renders the study of their organic remains easier than that of the European ? By whom was this advantage first pointed out ? * President of the American Geological Society, and of the Academy of Natural Sciences of Philadelphia, t See Silliman's American Journal of Science, vol. vii. p. 257. WORKS ON ORYCTOLOOY. 435 Works in the Department of Oryctology. The interest of the subject, and the importance of possessing resources for comparison between the fossiliferous beds of Europe and those of America, induce us to add here a rather greater num- ber than usual of works of reference, some of which it may not be easy to obtain without importing them expressly from Europe. We have ourselves encountered this difficulty, in endeavouring to procure several of the works named in the following list: Morton's Synopsis of Organic Remains. Silliman's American Journal of Science, vol. xxix., and many parts of the preceding volumes of the same work. Transactions of the Geological Society of Pennsylvania. Lea's Contributions to Geology. Harlan's Medical and Physical Researches. 1 vol. 8vo. Phila- delphia. 1835. Journal of the Academy of Natural Sciences of Philadelphia. 7 vols., hitherto published. Dr. Jacob Green's Monograph of North American Trilobites, with accompanying casts. Parkinson's Outlines of Oryctology. 1 vol. 8vo. London. 1822. Sowerby's Mineral Conchology. 2 vols. 8vo. 1812. Alex. Brogniart's Tableau des Terrains qui compose 1'ecorce du Globe. Transactions of the Geological Society of London. 5 vols. 4to. Deshayes, G. F. Description des Coquilles Fossiles des Envi- rons de Paris. Cuvier, G. Recherches surles Ossemens Fossiles. Essai d'une Expose de la Flore du Monde Primitive, par Gas- pard Comte de Sternberg. 1 vol. fol. Leipsic and Prague. 1820. J. S. Miller's Natural History of the Crinoidea. 1 vol. 4to. Bristol, England. 1821. Vegeteaux Fossiles, par M. Adolphe Brogniart, Paris. 1822. Townsend on Fossils. 1 vol. 4to. Bath, England. 1813. MantelPs Geology of the South Eastern parts of England. 1 vol. 4to. Witham's Internal Structure of Fossil Vegetables. 1833. METEOROLOGY. 1. FEW subjects connected with natural philosophy are more generally interesting than that which is about to engage our atten- tion. Meteorology maybe considered as a science supplementary to geology ; and as the latter relates to the state and constitution of the terrestrial globe, so the former regards the composition of the atmosphere, and the investigation of the constant changes that are taking place in it. " The quality of the air, as affected by cold or heat, moisture or dryness, and other circumstances, is distinguished by the term weather. The knowledge of the alterations of the weather, and of the laws by which they are governed, is styled weather-wisdom, (die witterungslehre,') or meteorology. 2. "This science is yet very imperfect, and requires for its improvement numerous and extensive observations."* Notwith- standing, however, the confessedly defective state of this branch of physical science, it is certainly one which has occupied the atten- tion of mankind in various ages, and in several different parts of the world ; but it is only in our own times that it has been studied with the attention due to it, both in an economical and in a philo- sophical point of view. To the navigator, the traveller, the hus- bandman, and numerous other classes of persons, the state of the weather, and the anticipation of the probable changes that may occur in it, must ever be topics of considerable interest and im- portance ; while the scientific inquirer will feel no less anxious to trace the laws by which meteorological phenomena are regulated, and to study their connexion with those of astronomy and geology. 3. One of the latest and most distinguished meteorological writers remarks, that " man may almost with propriety be said to be a meteorologist by nature : he is naturally placed in such a state of dependance on the elements, that to watch their vicis- situdes and anticipate their disturbances becomes a necessary portion of the labour to which he is born. The daily tasks of the mariner, the shepherd, and the husbandman, are regulated by meteorological observations ; and the obligation of constant atten- tion to the changes of the weather, has endued the most illiterate of the species with a certain degree of prescience of some of its most capricious alterations. Nor in the more artificial forms of society does the subject lose any of its universality of interest: much of the tact of experience is blunted and lost; but artificial means, derived from science, supply, perhaps inadequately, the deficiency ; and the general influence is still felt and acknowledged, What is meant by the term meteorology ? What is the actual state of meteorology, compared with other branches of physical science ? What is the value of this science in a practical point of view ? * Elements of Natural Philosophy by Professor Vieth, (Germ.,) p. 408. EXTENT OF THE ATMOSPHERE. 437 though not so accurately appreciated. The generality of this in- terest is, indeed, so absolute, that the common form of salutation among many nations is a meteorological wish, and the first intro- duction between strangers a meteorological observation."* 4. Meteorology, in ^its most extensive acceptation, has for its object not merely the observation of atmospherical phenomena, or of those occasional appearances styled meteors, to which the atten- tion of common observers has been generally limited, but it like- wise includes the rationale of terrestrial as well as atmospherical phenomena, whether accidental or permanent, which depend on the action of heat, electricity, magnetism, or light. Considered in this point of view, the subject will appear to be of immense extent ; and it may hence be characterized as the application of the laws of pyronomics, optics, and electro-magnetism, to the study of nature. 5. To take any thing like a complete survey of the science in all its bearings, would not only require a much greater space than the plan of this work will allow, but would also render it necessary to repeat much that has been introduced elsewhere, in illustration of topics discussed in some of the preceding treatises, both in the former and in the present volume. This essay on meteorology will, therefore, be confined to the investigation of the influence of moisture and temperature on the state of the atmosphere, and the explanation of the nature and causes of the most important meteoro- logical phenomena, with references to such subjects as have under- gone previous discussion. 6. The general properties of the atmosphere, as a permanently elastic fluid encompassing on all sides the solid globe of the earth, and indefinitely extended from its surface, have been pointed out and illustrated in the treatise on Pneumatics. It has been stated, that at the height of fifty miles the air does not possess sufficient density to reflect the rays of light ; and though it is not improbable that the atmosphere may exist at a still greater elevation, yet the speculations of Dr. Wollaston go far to prove that it must have certain limits, beyond which the ethereal medium must be of such extreme tenuity as to occasion no appreciable resistance to the re- volutions of the planets round the sun : for if they revolved in a resisting medium like the air, the regularity and uniform extent of their orbits would be disturbed, contrary to what may be con- cluded from a comparison of astronomical observations made at different and remote periods.f What evidence does the intercourse of common life present of the general interest taken in the subject of meteorology ? What range of inquiries is embraced by the science of meteorology ? In what relation does it stand to the imponderable agents explained in other departments of science? What evidence is derived from astronomy in favour of the finite extent of the atmosphere? * Daniell's Meteorological Essays and Observations, 2d edit, t It should, however, be remarked, that the observations of astronomers during a period of even two thousand years, can afford no conclusive evi- 2o2 438 METEOROLOGY. 7. The peculiar temperaments of various organized beings qualify them respectively for the several situations they inhabit. The deepest abysses of the sea are probably destitute of animated beings, but the gigantic whale can descend to a vast depth beneath the surface of the ocean, though breathing the air like man, and consequently unable to remain deprived of it but for a com- paratively short period ; and the polype lays the foundation of his coral cells on rocks often apparently far beneath the usual abodes of the finny tribes. On the other hand, the condor dwells in the upper regions of the air, and wings his steady flight over the sum- mits of Pinchincha or Chimborazo, which are among the loftiest peaks of the mighty Andes.* Inflamed bodies would become ex- tinguished for want of air at the height of about 20,000 yards above the sea ; hydrogen gas would no longer deserve the name of inflammable air at 25,000 yards; and sulphur would be incom- bustible at 30,000 yards, if it was possible for it to be transported to such an elevation. 8. The temperature of the atmosphere diminishes in proportion to the elevation above the level of the sea. The degree of tem- perature, however, is further influenced by other causes, and should be estimated with reference to the normal heat of plains, whence may be deduced the direction of isothermal lines for summer and winter ;f depending more or less on the mass and configuration of mountains; the strata of clouds or vapours which may intercept the radiation of heat from plains below ; and likewise on the winds or currents of air passing horizontally from one zone to another of a different temperature.^ What examples of self-adaptation is exhibited by fish, animals, and men ? How does the temperature of the atmosphere vary ? dence of the non-existence of a highly attenuated but resisting medium, beyond the atmospheres of the earth and other planets. For though it may require a lapse of millions of ages before the orbits of these dense bodies can be sensibly affected by the medium they traverse, yet lighter bodies, such as comets are supposed to be, may afford indications that the celestial space is not an absolute vacuum. See Treatise on Geology, p. 316. * We have been informed by a gentleman who has spent several years in the Peruvian mining district, about 12 south latitude, and at an eleva- tion of 16,000 feet above the level of the ocean, that he has repeatedly seen the condor sailing high above the loftiest of the snowy Cordilleras with no apparent motion of the wings, and yet in an air so attenuated that, where himself was stationed, at thousands of feet below, the rarity of the atmosphere rendered all effort painful to those not long accustomed to the light medium there prevalent. But the native Indian miners exhibit nothing of the same inconvenience. ED. t These have been also denominated isotheral and isocheimal lines ; the former signifying lines of equal temperature for the summer season, and the latter lines of equal winter temperature. See Report of the British Association, 1832, pp. 217, 218. t For observations on the extremes of heat and cold which have oc- curred in different regions, and relative to the mean temperature of the poles and the equator, see Scientific Class Book, pt. i., Pyronomics, pp. 282 285. And for an account of the direction and extent of isothermal VARIATIONS OF ATMOSPHERIC PRESSURE. 439 9. The gravity of the air, and the continual variations taking place in it, are among the most important causes of several atmospheric phenomena. Abundance of facts demonstrate that the weight of a column of air, of any given diameter, is equal to that of a similar column of water 33 feet in height, or of a column of mercury 30 inches high. Such is nearly the amount of the mean gravity of the atmosphere at the level of the sea.* Its relative gravitating force or pressure must of course decrease in ascending above the surface of the earth : but augmentations and diminutions of that force are observable at the same place, which must there- fore arise from circumstances independent of local elevation. 10. These alterations of atmospheric pressure may probably have a considerable effect on the animal creation. They are indi- cated by the rising or depression of a column of mercury, in- closed in a glass tube, forming the well-known instrument called a barometer. It has been computed, that the weight of air com- monly pressing on the surface of the body of a man of middle size, is about 30,0001bs., hence a -variation of height in the mercu- rial column of only a single line must indicate an alteration of atmospheric pressure to the extent of about 84lbs. 11. The variations of pressure that have been observed are either periodical or occasional. The horary variations are the most import- ant. From the observations of M. Ramond, it appeared that the barometer attained its maximum height at 9 A. M. and at 11 p. M. ; and its minimum at 4 A. M. and 4 p. M. These variations take place with greater regularity between the tropics than in the temperate zones ; and we learn from the investigations of Humboldt, that near the equator the barometer attains a maximum at 9 A. M. and p. M., and a minimum at 3 or 4 A. M. and p. M. so constantly, that, in almost all states of the air, the height of the barometer will indicate the time of day. The causes of these horary oscillations are somewhat obscure ; though it appears probable that they chiefly depend on temperature. 12. The occasional variations of atmospheric pressure seem to be intimately connected with the direction of the wind. Theatre greatly influenced by latitude. "At the equator they may be said How is the pressure of the air affected by the height to which we ascend? How are variations of pressure in the air commonly ascertained ? To how many sorts of variation is .the pressure of the air subject ? V^hich of these deserve most attention ? At what hours of the day do the maxima and minima of pressure occur in the tropical regions ? To what purpose might the horary variation be there applied ? zones, the mean temperatures of days, months, and seasons, and the extreme temperatures of climates, see Pomllet Elem. de Physique et de Meteoro- logie, torn. ii. pp. 628 638 ; and Encyclop. Metrop., vol. iv., Meteorology. * The mean height of the barometer at London, for the year 1788, was 29.96 inches ; for 1789, 29.79 in. ; and for 1790, 29.98 inches. Dr. Dalton's Meteorological Observations and Essays. 2d edit., 1834 ; from Philosophi- cal Transactions. 440 METEOROLOGY. to be almost reduced to nothing ; for it rarely happens that any change takes place to interfere with the regular course of the di- urnal tides. A hurricane creates almost the only exception. The amount of variability increases towards the poles, in a great mea- sure owing, probably, to the irregularity of the winds beyond the tropics. The mean amount of variation may be stated at the equator at two lines, in France at ten lines, in Scotland at fifteen lines, throughout the year; but this quantity has its monthly os- cillations."* Winds. 13. The atmosphere may be considered as consisting of a mul- titude of concentric strata, the density of which decreases in pro- portion to their height above the surface of the sea. While an equilibrium exists between the different parts of the aerial mass, it remains calm and tranquil ; but if the equilibrium be broken by any cause whatever, the mass becomes agitated, and that kind of motion in the air takes place which is termed wind. Among the general causes that destroy the equilibrium of the atmospheric strata, the most common are change of temperature or pressure, tides, and great currents of water, the rotatory motion of the earth, the hygrometric or the electric state of the air, and the action of the sun and the moon. There are others, the influence of which is less extensive, as earthquakes and the eruptions of volcanos. 14. Alteration of temperature is, perhaps, the most usual as well as the most important cause of aerial currents or winds. When one portion of a mass of air becomes more heated than those parts by which it is surrounded, it is rarefied and rendered lighter than be- fore ; so that it ascends to a higher level, while the adjacent colder and denser air rushing in to supply its place, streams of air tend from all points towards that where the partial vacuum has thus been formed. Professor Pouillet remarks, that winds may be propa- gated by impulsion and by aspiration. We designate thus the two opposite modes which ought to be carefully distinguished. Wind is propagated by impulsion, when it blows towards a place in one direction, and its progressive march is in the same direction : thus it is with the wind that issues from a pair of bellows, when the included air is compressed. 15. Wind is propagated by aspiration, when the blast takes place in one direction, and the progressive march of the wind is What is the mean amount of variation in pressure in high and in low latitudes, respectively ? What are the chief causes which destroy the equilibrium of pressure in the air ? In what manner may we conceive masses of air to be set in motion by heat ? What distinction has been'made by Pouillet in regard to the directions in which wind is propagated ? * Forbes on Meteorology Report of Brit. Assoc. for 1832. p. 235. AERIAL CURRENTS 441 in a contrary direction : this is what happens when the wind en- ters a pair of bellows in which the air is rarefied ; for the blast rushes towards the nozzle, but the progressive march of the cur- rent is in an opposite direction ; for the most distant points whence the air is drawn last receive the impression. This latter mode is not so unusual as might be imagined, as will appear from the phenomena of hurricanes. Wargentine has also made similar re- marks on the winds in the north of Europe. He says : " When the wind proceeds from the west it is felt at Moscow earlier than at Abo, though the latter city is about 400 leagues farther westward than Moscow ; and this wind does not reach Sweden till after it has blown over Finland."* 16. The manner in which winds are produced by changes of temperature may be illustrated by some simple experiments. The production of a current by lowering the temperature of a portion of air may be exhibited by means of the ap- s paratus represented in the margin. Tie a piece of wet bladder over the mouth, C D, of the bottle, F G C D, after having poured into it as much water as will half-fill the neck when the bottle is inverted. Then take a large bladder, H K L I, and cut off the neck of it in such a manner as to leave a considerable opening, I H ; and having made a hole in it at K L, the neck of the bottle is to be put through it, and the edges of the bladder must be tied fast round the bottle, so that no liquid may pass between the bladder and the bottle. Next throw a table-spoonful or two of common salt, and as much again of snow into the bladder, and upon the globular part of the bottle, and stir them together with a stick or wooden spoon. The snow and salt will then begin to melt, absorbing the heat from the bot- tle with which they are in contact, and from the air within it, which will thus become cooled down to such a degree that it would freeze the water in the neck of the bottle if it reached above the part at which the bladder is tied ; and as this mighUem- barrass the experiment, but a small quantity of water should be What evidence of the effect of aspiration is exhibited in the north of Europe ? What in America ? Illustrate this effect by experiment ? * Pouillet Elem. de Phys. Exper. et de Meteorol. 2nde edit. 1832. torn, ii. pp. 715, 716. The credit of having established the fact that winds blow earlier to- wards the spot at which the greatest disturbance of equilibrium takes place, at points near, than at others more remote from that spot, is due to Dr. Franklin who remarked that, along the Atlantic coast of America, north-east storms begin in the south-west, and proceed to windward some- times at the rate of more than 100 miles per hour. The observation was strikingly illustrated in the case of a solar eclipse being visible at Boston, while at Charleston, S C., the prevalence of a north-east storm prevented its being seen. ED. 442 METEOROLOGY. introduced. Now the air within the bottle being 1 condensed, and having its elasticity weakened by the deprivation of heat, while the external air, which is not so cold, retains more expansive power, it will force its way into the bottle, and produce a current, on the bladder, C D, being punctured with a large pin at E. The air will then be seen rising up in bubbles, with considerable velocity, through the water in the neck of the bottle, till the equilibrium is restored between the external and the inclosed air. 17. The converse of the preceding experiment may be performed by slightly varying the apparatus already described. Take a bottle encompassed with a bladder, as before, and leaving it open, turn it upside down, with the mouth upon a plate or shallow dish, in which has been put a sufficient quantity of water to cut off the connexion between the air in the bottle and the external air. Then pour hot water upon the bottom of the bottle, and into the bladder surround- ing it. The heat thus applied will expand the air in the bottle, which will issue out in a current, through the water in the plate, producing a mimic wind, that may be felt on holding the hand near the place where the air escapes. 18. These experiments show the different modes of propagation of aerial currents which Pouillet has indicated. The stream of air rising through the water into the first bottle, (in which a partial vacuum has been formed by reduction of temperature,) is obviously a current of aspiration ; and that issuing from the second bottle, through the expansion of the included air by heat, is a current of impulsion. Each of these methods of propagation of blasts of wind may doubtless be sometimes distinguished ; but it seems probable that winds in general should be regarded as the joint effect of ex- pansion and pressure in one part of the atmosphere, and condensa- tion in another. This must obviously be the case, since but for the exterior pressure, air would have no tendency to rush into the void created by condensation. 19. Some interesting "Facts and Observations relating to the Winds, Waves, and other Phenojena, by which the Surface of the Sea is affected," were published by Captain Horsburgh, in Nicholson's "Journal of Natural Philosophy," which serve to show that a descending current of air may be propagated in various directions. He says : " I have several times, in calm weather, seen a cloud generate and diffuse a breeze on the surface of the sea, which spread in different directions from the place of descent. A remarkable instance of this occurred in Malacca strait, during a calm day, when a fleet was in company : a breeze commenced suddenly from a dense cloud ; its centre of action seemed to be in the middle of the fleet, which was much scattered. The breeze spread in every direction from a centre, and produced How may the production of wind by increase of temperature be illus- trated ? What concurrence of causes is found wherever wind is produced ? What evidence has been adduced to prove that the descent of of air may produce radiating currents of wind ? REGULAR AND VARIABLE WINDS. 443 a singular appearance in the fleet, for every ship hauled close to the wind as the breeze reached her, and, when it became general, exhibited to view the different ships sailing completely round a circle, although all hauled close to the wind."* 20. Captain Horsburgh afterwards says : " It frequently happens during a ty-fong in the China sea, that the waves run in every di- rection ; having the appearance of elevated mounts or pyramids, which infringe on each other with great violence. Ships are very liable to lose their rudders, when these pyramids strike against them ; and the masts are endangered by the quick, turbulent mo- tion proceeding from such heterogeneous impulse. "f He also states, that the swell of the sea caused by a storm may be pro- pagated with a greater mean velocity than the storm that causes it, and may therefore arrive on a coast before it, or come after the storm has ceased. These phenomena he attributes to the inter- ference of contrary winds. 21. Winds may be distinguished as being either regular or variable. Among the former are the trade winds, between the tropics ; the monsoons, in the Arabian, Indian, and Chinese seas : and the sea and land breezes. 22. Over the Atlantic and Pacific oceans, the trade winds blow- ing permanently westward, extend from 30 N. to 30 S. latitude. When the sun is on the equator, the trade winds, in sailing north- ward, veer more and more from the east towards the north ; so that at their limit they become nearly NE. ; and on the contrary, in sailing southward, they become at last almost SE. When the sun is near the Tropic of Cancer, the trade winds north of the equator become more nearly east than at other times, and those south of the equator more nearly south ; the contrary phenomena are observed when the sun is near the Tropic of Capricorn. The trade wind becomes due east, not exactly upon the equator, but about 4 N. of it. 23. These intertropical winds are the effects of the diurnal ac- tion of the sun in raising the temperature of the atmosphere over those points of the earth's surface where its beams are vertical, com- bined with those arising from the earth's motion on its axis. The lower strata of the atmosphere, near the equator, becoming heated and rarefied by the sun, form ascending currents, spreading towards the poles ; while under currents, from the north and south pole respectively, flow in to supply the partial vacuum caused by the condensation of the air over the equatorial space. The polar cur- rents, which would otherwise meet and destroy each other at the equator or near it, are modified by the motion of the earth ; fpoint in meteorology f How may the variation of that point be illustrated l * Poullet Elem. de Phys. et Meteorol., torn. ii. pp. 737741. t Dr. Dalton was, perhaps, the first English philosopher who pointed out the importance of the dew-point, as a hygroscopical phenomenon, in a series of Essays published in the Manchester Transactions, vol. v. First Series. But a kind of hygrometer involving this principle was long pre- viously invented by an ingenious Frenchman. " M. le Roy prescrivoit, pour moyen hygrometrique, de tenir dans 1'air un verre plein d'eau, et dont la temperature fut la meme que ceHe de 1'air ; de refroidir lentement cette eau par une addition graduee et successive d'eau a la glace, et de noter, le degre de froid auquel on commeneeroit a voir a la surface du verre cette le"gere rosee qui indiqne la precipitation des vapeurs, et par consequent la supersaturation de 1'air contigu au verre. II jugeoit 1'air d'autant moins humide, qu'il falloit un degre de froid plus considerable pour operer cette precipitation." Sigand de la Fond El6m. de Physique, fom. iii. p. 354. V. Le Roy Essais sur-l'Hygrometrie, p. 57. 8P2 450 METEOROLOGY. hours, and the fire was kept up. The temperature increased to 58, and the point of condensation rose to 52."* 43. Among the instruments that have been invented to ascertain the hygrometric state of the atmosphere with relation to its tem- perature, may be mentioned the hygrometers of Professor Daniell and of Professor Pouillet. Both consist of apparatus adapted to show the temperature of a body on the surface of which dew begins to form, and which may be compared with that of the air from which it is precipitated. f 44. " A very simple, as well as accurate, method of taking the dew-point, is to use a thin tumbler of tin, kept very bright and clean on the outside and in the summer cold water, and in the winter snow or ice, and if necessary salt, mingled with water and when these are not at hand, a mixture of muriate of ammonia and nitrate of potash, in equal quantities, pounded very fine, put into the tumbler with water. By any of these means a temperature may soon be obtained below the dew point. When dew settles on the tumbler it must be carefully wiped off, very dry, and the fluid within Ktirred with a thermometer and this must be repeated until the fluid is gradually heated up by the air, so that the moisture ceases to settle : the highest temperature at which it will settle is the dew point." The same point may be obtained approximately by the following method : " Take two thermometers that agree, or allow for the difference ; cover one of them with a piece of wet white cloth, and swing them simultaneously in the air, (unless the wind is blowing fresh;) when it is dicovered that they cease to change by swinging, or by the effect of the wind, take 103 times their difference, and divide it by the wet-bulb temperature, and substract the quotient from the temperature of the naked-bulb the remainder will be the dew-point. This formula is founded on experiments from 20 Fahr. to 80, and does not differ at either extreme from the most careful experiments."^ Clouds. 45. Since the condensation of aerial vapour depends on the temperature of the atmosphere, it is manifest that it may exist in a much larger proportion in warm climates than in those that are colder. Thus the air in the cloudy climate of England is In what manner may the dew-point be obtained by refrigeration and the use of a common thermometer ? How may it otherwise be approximately obtained ? * Brande's Journal of Science, vol. viii. p. 321. t For a descriptive account of Daniell's hygrometer, see papers in Brande's Journal of Science, vol. viii. p. 300 ; and Met. Essays and Obs. Pouillet's Hygrometre d Capsule is described in his Elem. de Phys. et de Meteorologie, torn. ii. p. 733 ; and some others, constructed on similar principles, are noticed by Mr. Forbes, in Report of British Assoc. for 1832. t See the Circular prepared by the joint commitees of the Franklin In stitute; and the Philosophical Society of Philadelphia. FORMATION OF CLOUDS. 451 upon the whole less loaded with moisture than that beneath the clear sky of southern countries ; and consequently more rain generally falls during a year at Naples than in London, and more at Calcutta than at Naples. At the equator the air, relatively to its temperature, contains less moisture than in the temperate zone, though the actual amount of moisture is larger. That is, the air, near the surface of the earth, under the line, has a greater capacity for moisture than air at the same height in colder regions ; but in thu latter, the actual quantity, (though smaller in a given bulk of air,) approaches more nearly to the point of saturation, without any where reaching that point ; for when it does, precipitation takes place. 46. " Hence, at the equator, the air immediately incumbent on the earth's surface must be comparatively very dry. Moreover, the cause which produces the dryness of the equatorial air, at the earth's surface, must, all over the globe, exert different degrees of the same influence. The air every where incumbent on the earth's surface must, therefore, always be under the point of satu- ration; the relative degree of dryness being highest, under the equator, and gradually diminishing as we recede north or south toward the poles. 5 '* 47. Clouds consist of visible vapour, or meteoric moisture in the intermediate state between invisible vapour and palpable liquid. Their formation appears to be the result of the imperfect condensation of invisible vapour, from the intermixture of strata of air at different temperatures. Evaporation is perpetually taking place from the surface of the earth, not alone from seas, lakes, &nd rivers, but in some degree from the hard rock or the frozen soil.f The watery exhalations are usually imperceptible, unless when a rapid change of temperature occurs, as on a sudden thaw after a hard frost, when the damp earth and the waters throw off abundance of reeking vapour. At other times, the transfer of the aqueous fluid from the earth to the atmosphere, though not interrupted, is less distinctly observable. 48. " During the heat of the day it rises from the surface of the land and waters, and reaches its point of condensation in greater or less quantities at different altitudes. Partial clouds are formed in different parallel planes, which always maintain their relative distances. The denser forms of the lower strata, as they float along with the wind, show that the greater abundance of precipi- Considered with reference to the temperature, in what zones is the quantity of moisture greatest ? What is the hygrometric state of air at the equator, near the ground ? What is the nature and cause of clouds ? * Dr. Prout's Chemistry and Meteorology, p. 287. From the latter part of Dr. Prout's opinion there may be reason to dissent ; for though the abso- lute quantity of moisture towards the poles may be less, the difference in high and low situations may still bo as great as in the equatorial re- gions. The air at the surface is saturated when fogs cover it. ED. t See Scientific Class Book, pt. i. p. 308. 452 METEOROLOGY. tation has been at the first point of deposition, while the feathery shapes and lighter texture of the upper attest a rarer atmosphere. These elouds do not increase beyond a certain point, and often re- main stationary in quantity and figure for many hours ; but as the heat declines, they gradually melt away, till at length, when tfu3 sun has sunk below the horizon, the ether is unspotted and trans- parent. The stars shine through the night with undimmed lustre, and the sun rises in the morning in his brightest splendour. The clouds again begin to form, increase to a certain limit, and vanish with the evening shades. 49. This gradation of changes, which we see so often repeated in our finest seasons, may at first seem contrary to the true prin- ciples ; and the precipitations which occur with the increase of temperature and disappear with its c?:c/me, may, without reflection, be regarded as diametrically opposite to correct theory. But a little consideration will show that such conclusions would be u,n- true. The vapour rises, and is condensed ; but in its descent falls into a warmer air, where it is again evaporated, and becomes invisible ; and as the quantity of evaporation from the surface of the earth is exactly equal to supply this process above, the cloud neither augments nor decreases. When the sun declines, the ground cools more rapidly than the air ; evaporation decreases, but the dissolution of the cloud continues. The supply at length totally ceases, and the cloud subsides completely away. The morning sun revives the exhalations of the earth, the process of their condensation and consequent cloud-like form commences, and they again undergo the same series of changes."* .50. Clouds differ from fogs only in their superior elevation above the surface of the earth. "They are seldom a mile high in our climate in winter; in summer they may perhaps occasionally be two or three miles high. The thickness of a stratum of clouds, or distance from the under to the upper surface, is also variable, from a few yards to three or four hundred or more. A stratum of cloud of greater depth is probably of rare occurrence any where ; it would produce a greater degree of darkness on the earth's sur- face than is ever observed. "f 51. Different opinions have been proposed as to the constitution f the clouds. They are usually regarded as consisting of little JL In what part of a series of clouds does the precipitation of moisture from the invisible state appear to be most copious ? What succession of appearances recurs, during fine weather, in tempo rate climates? How is this reconciled with the principles of greater evaporation being caused by higher temperatures? What is probably the greatest thickness of clouds in a vertical direction* * Daniell's Meteorological Essays and Observations, pp. 124, 12. 1 Dr. Dal ton's Meteorolog, Observations and Essays, App, to 2d edition Note -{A.] The sequel of this note contains an instructive account of phenomena relating to clouds, observed during excursions in the more elevated parts of several counties in England. MODIFICATIONS OF CLOUDS. 453 vesicles of water filled with humid air.* As to the cause of their ascent or suspension in the atmosphere, M. Gay Lussac refers it to the impulsion of ascending currents, owing to the difference of temperature between the surface of the earth and that of the up- per air ; while M. Fresnel supposed that the solar heat, absorbed by clouds, formed groups of miniature moritgolfieres, which rise to heights depending on their excess of temperature above that of the air. 52. Dr, Dalton has advanced a different hypothesis, considering clouds as being composed of water only, in a state of extreme di- vision. He says : " When a precipitation of vapour takes place, a multitude of exceedingly small drops form a cloud, mist, or fog : these drops, though eight hundred times denser than the air, at first descend very slowly, owing to the resistance of the air, which produces a greater effect as the drops are smaller."! This last view of the nature of clouds has been recently brought forward by Prof. Stevelly at the Edinburg meeting of the British Association. He alleged that clouds were assemblages of spherules of water, the production of which might be accounted for by the laws of capil- lary attraction; and he very justly remarked, that notwithstanding their actual specific gravity, compared with that of air, " the mi- nute size of the cloudy spherules would alone be sufficient practi- cally to suspend them, as even gold and platina may be so subdi- vided as to descend with less than any assignable velocity.":*: 53. Either of these theories may be employed to account for the phenomena ; but, as Professor Pouillet remarks, " We at present do not possess sufficient data concerning the real constitution of clouds, and the properties of the vapours, or the different elements which compose them, on which to ground a satisfactory explana- tion of their various appearances."^ Modifications of Clouds. 54. The ever-changing varieties of form which clouds exhibit to the eye of the observer, seem to bid defiance to all attempts at classification. The task, however, has been undertaken by Mr. Luke Howard, who after a long series of meteorological re- searches, formed a systematic arrangement of clouds, distin- What opinions have been advanced to explain the constitution of clouds ? What is the hypothesis of Gay Lussac ? How has Professor Stevelly sought to account for the suspension of the spherules of visible vapour in the air? * " On ad met, en general, que les vapeurs qui constituent les nuages sont des vapeurs vdsiculaires, c'est a dire, des amas de petits globules rernplis d'air humide, tout-a-fait analogues aux bulles de savon." Pouillet EUm. de Phys. et de Meltorol., torn. ii. p. 753. t Meteorological Observations and Essays, p. 134. i Report of Professor Stevelly's Observations in the Athenaeum, for Sept 27, 1834. $ Elenou de Phys. et de Meteorol., torn, ii, p. 754. 454 METEOROLOGY. guishing them by names characteristic of their general structure and mode of production. The classification and terminology pro- posed by this ingenious philosopher, have since been adopted by many writers ; and Mr. Howard himself, after eighteen years' ex- perience, thus states his confidence in the propriety of his method : " I do not find a necessity either to make additions to this little system, or to retrench any of its parts. Some subordinate distinc- tions may, indeed, at a future period, be found useful ; but until the classification, as it is, be generally adopted, its simplicity must form its most powerful recommendation, and its conformity to nature. It is in the form and structure, carefully considered with due reference to situation, that the observer will find the basis of a correct judgment ; and he will do well to wait, at first, for se- veral successive appearances of each modification, to which he will thus at length find the definition apply in all its parts."* 55. The modifications of clouds are distinguished into three principal distinct formations, and four composite kinds. The sim- ple forms are the cirrus, in which the vapours have the appear- ance of loose, narrow bands of parallel or diverging feathery fibres; the cumulus, exhibiting heaped masses of a globular or conical shape ; and the stratus, forming extended level sheets of cloud. The composite clouds are the cirrocumulus, consisting of collections of small but well-defined orbicular masses, or little cu- muli ; the cirro-stratus, in horizontal or somewhat oblique sheets, having a light, fibrous appearance above, and a concave or undu- lated surface below ; the cumulo-stratus, generally flattened at the base, and heaped above with overhanging protuberances ; and the nimbus, composed of dense continuous masses, forming a canopy of vapour dissolving below into rain. 56. Dr. Thomas Forster, who has long been an industrious observer of atmospheric phenomena, and has distinguished him- self by his writings on meteorology, has adopted Mr. Howard's system, which he has endeavoured to familiarize by the addition of English names for the several modifications of clouds. To the statement of these terms may be properly added a few notices of the modes of formation of the different varieties, and of the infer- ences that may be drawn from their appearance relative to changes of weather. 57. CIRRUS, or CURLCLOUD. This delicate modification, with its varieties, may be distinguished by its fleecy or filmy light- ness, fibrous structure, and instabilty of form ; seldom long pre- serving the same appearance. It commonly occupies the higher regions of the air. In variable and warm weather, with gentle breezes in summer, long obliquely descending bands of cirri are What nomenclature lias been found to distinguish the several kinds of clouds ? What are the characters of the several compound clouds ? * The Climate of London, deduced from Meteorological Observations, p. L MODIFICATIONS OP CLOUDS. 455 sometimes seen connecting masses of other modifications, pre- viously to rain. After a continuance of fine clear weather, the cirrus may be seen crossing the sky at a great height, like a white thread, the extremities of which seem lost in the horizon. This is called the Linear cirrus. When several of these long clouds are connected by transverse or oblique processes, they have been termed, from their net-like arrangement, Reticular cirri. the most usual form of the cirrus is that called the Comoid, or Mare 's-tail cirrus, which commonly occurs in variable wea- ther, indicating the approach of wind or rain. When care- fully observed, the cirri will be found to exhibit signs of internal commotion, without any change of place ; though sometimes the fibres seem to wave gently to and fro. This happens most fre- quently in those large and lofty cirri, with rounded heads and long pointed tails, which are common in summer and autumn, during the prevalence of dry winds. 58. CUMULUS, or STACKENCLOUD. This cloud is readily dis- tinguished by its irregularly hemispherical figure, having gene- rally a level base. It is produced by the gathering of detached masses, which then appear stacked or piled together. Its for- mation may be most advantageously traced in fine settled wea- ther. About sunrise, small, thinly-scattered specks of clouds may be perceived ; which, as the sun ascends, increase in bulk, coalesce, and at length form the complete cumulus. It has been termed the cloud of day, as it generally dissolves in the evening, separating first into small fragments, and retracing the steps of its formation in a reversed order. The more regularly-rounded cumuli, of a whitish colour, which reflect a bright silvery light when opposite the sun, are the harbingers of fine weather ; but those of a more indeterminate figure, with a dark hue and irregu- lar fleecy protuberances, prognosticate rain. 59. STRATUS, or FALLCLOUD. The stratus is nothing more than that bed of vapour which covers the surface of the earth during the absence of the sun, or when its rays are impeded, sometimes creeping as a mist over the valleys and low lands, and disap- pearing soon after sunrise ; and at others, hovering in the shape of a dingy fog, at a small elevation in the air, during one or per- haps several days. In its usual form of a summer-evening mist, it owes its origin to the nocturnal depression of temperature in the lower region of the atmosphere. It may be observed in a fine evening, after a hot day, when the cumuli which have pre- vailed through the day decrease, that a white haze forms close to the ground, and veils its surface. About midnight it attains its utmost density, and disappears towards sunrise. It has hence In what states of weather is the cirrus? Enumerate some of its varieties ? What is found to be the action of the parts of this kind of clouds among themselves ? What distinguishes the cumulus from other forms of clouds? By what familiar name is it designated ? Why ? 456 METEOROLOGY. been called the cloud ofni^ttt. In autumn the longer continuance of this cloud marks the diminution of the sun's power. But in winter it sometimes assumes the form of a dense fog, shrouding in dismal darkness every object on the earth, especially in the atmo- sphere of some large cities ; the obscurity being augmented by the intermixture of smoke with the watery vapour. In January, 1814, one of these fogs pervaded the air, over a great part of the south end west of England, for about a fortnight. The stratus is often found to be positively electrified ; and hence it does not wet ob- jects in contact with it. This modification must not be con- founded with some varieties of cirrostratus, which resemble it in appearance ; but the latter wets every thing it touches, and thus the two forms may be distinguished. 60. CIRROCUMULUS, or SONDERCLOUD* The name of this cloud indicates its affinity to two of the principal forms. It differs from some varieties of the cirrostratus, by the superior density and compactness of its component nubeculae, and the greater diversity of arrangement. At the approach of thunder storms cir- rostrati appear in masses of a denser structure, more rounded shape, and in closer order than at other times. In rainy, change- able weather, these clouds, have a light, fleecy texture, and varia- ble figure, being scarcely to be discriminated from cirrostrati. In summer the cirrocumulus forebodes heat; and in winter, the breaking up of frost, and approach of mild, wet weather. 61. CIRROSTRATUS, or WANECLOUD. From its disposition to rapid alteration of figure and subsidence, this kind of cloud has derived its English appellation. It is remarkable for its shallow depth relatively to its horizontal extent; while in other respects it is constantly varying. It originates more fre- quently from the cirrus than from any other modification ; and sometimes after descending from a higher station, and assuming its characteristic figure, it changes again into cirri ; but more commonly it either evaporates, or unites with some other kind of cloud, producing cumulostratus, nimbus, and then falling in rain. Besides its common appearance, as a long, plain streak of cloud, tapering towards the extremities, it assumes the form of the Mottled cirrostratus, constituting what is called the mackerel-back sky of summer evenings, which has been pro- verbially reckoned a sign of dry weather. The Cymoid cirrus is accounted a variety of the cirrostratus. It is composed of waving bars or streaks, either arranged so as to form lines, or otherwise disposed. It is sajwl to be a sure indication of approaching storms. Another variety of the cirrostratus is that large shallow veil of cloud which occurs especially towards At \vhat hour of the day is the stratus most dense ? To what designation has this circumstance given rise ? What inihi :I:IMMS, in regard to weather, are supposed to be afforded by the cirrocumulus ? What is the familiar appellation applied to the mottled cirrostratus? What is supposed to be prognosticated by the cymoid cirrus! RAIN, HAIL, AND SNOW. 457 night, and through which the sun and moon appear but indis- tinctly. Halos, parhelia, &c., usually are formed by peculiar refractions of the light of those bodies in this variety of cloud. It betokens rain or snow. 62. CUMULOSTRATUS, or TWAINCLOUD. This modification of cloud is produced by the accumulation of other kinds, as the cirrus and cumulus. The cumulus, driven by the wind, becoming retarded in its course, grows denser, spreads laterally, and swells out into a dark, irregular mass. Sometimes a number of cumuli unite at the base, from which heaps of vapour rise in the form of mountain peaks, or detached rocks. The cumulostrati, which give birth to storms of hail or thunder and lightning, often look black and lowering, especially before the shower of hail or rain begins to fall. Occasionally, the clouds of this modification eva- porate, or the mass separates into cumuli ; but more commonly their appearance is followed by that of the nimbus, producing rain or snow. 63. NIMBUS, or RAINCLOUD. Any of the other modifications of clouds may form and again disperse, or become evanescent; but the nimbus is a constant precursor of a storm. It may be best observed when showers fall at a distance, and the nimbus can be seen in profile. The progress of its formation may be infer- red from what has been just described, under the preceding modi- fication. The cumulostratus having been formed, sometimes goes on increasing in density till the whole horizon is veiled in por- tentous darkness. Shortly after which the lowering sky assumes a gray obscurity, denoting a new arrangement of the particles of vapour in the cloudy mass. The nimbus is then formed, and rain descends. The shower continues till the nimbus is exhausted, and other modifications of cloud reappear : the cirrus, the cirros- tratus, or perhaps the cirrocumulus, are seen aloft, floating amidst the blue sky ; and the remaining cumulus, no longer retarded, sails along with the wind nearer the surface of the earth. Rain, Snow, and Hail. 64. One immediate cause of rain is probably the intermixture of masses of air, whose common temperature is insufficient to keep suspended their joint amount of moisture, part of which is therefore precipitated. Another is the ascent, into an elevated region, of warm air fully supplied with vapour, whereby an expansion* and an increase of capacity for heat, with a diminution of temperature, What forms does the cumulostratus exhibit previous to a hail storm or thunder shower ? How does the nimbus differ from other forms of clouds ? What are supposed to be the two immediate causes of rain ? * The effect of sudden expansion in the receiver of an air-pump is to cause invisible to change for a moment to visible vapour, and to fall in miniature rain. Before reaching the pump-plate this little shower will sometimes be seen to disappear as the temperature resumes its former state. ED. 2Q 458 METEOROLOGY. takes place. Contending currents in the atmosphere bring, sud- denly, into mutual contact vast fields of moist air, and the aqueous particles coalescing form drops, which, if the temperature is above the freezing point, descend in liquid showers. The size of the drops of rain probably depends on the degree of rapidity with which condensation takes place; and the rate at which they de- scend must be influenced by the relative height of the clouds, the action of the wind, and their own magnitude. 65. The mean quantity of rain that falls in different parts of the world varies considerably, according to local circumstances. Among these are temperature, distance from the sea, and position with respect to mountain chains. According to Humboldt, nearly six times as much rain falls at the equator as in 60 N. latitude. But in the tropical regions the rains, though vastly more abundant than in cold climates, are much less frequent ; and in the former, the rains are periodical. Mountainous tracts are visited with more copious and frequent showers, in general, than plains ; and in some countries little or no rain falls, as in Egypt, the fertility of which depends on the periodical inundations of the Nile. 66. It has been repeatedly remarked, that in any given situation the quantity of rain is greatest at the least elevation : thus more might be collected within an area 12 inches square at the bottom than at the top of a high tower, all other circumstances, except the height above the ground, being equal. An experimental in- vestigation of the cause of this phenomenon has been undertaken by Mr* John Phillips, of York, England, an account of which may be found in the Report of the British Association for 1833. The hypothesis which he proposes, as a probable inference from the result of his researches, is, " that the whole difference in the quantity of rain at different heights above the neighbouring ground, is caused by the continual augmentation of each drop of rain from the commencement to the end of the descent, as it traverses suc- cessively the humid strata of air of a temperature so much lower than that of the surrounding medium as to cause the deposition of moisture upon its surface." Mr. Phillips purposes to pursue the inquiry, with a view towards the completion of the theory of this curious subject, the patient investigation of which, as he justly remarks, cannot fail to give us new and penetrating views into the constitution of the atmosphere.* 67. When the temperature of the region of the air in which the resolution of the cloudy vapour into water takes place hap- pens to be below the freezing point, the globules, in the act On what does the size of the drops depend ? What local circumstances appear to affect the quantity of rain falling on any given portion of the earth's surface? What relation appears to subsist between the elevation of a plain and the quantity of rain which falls upon it? To what is the observed difference attributed ? * Report of British Association, for 1833, pp. 410 412. SNOW, HAIL, &C. 459 of union, become congealed into needle-shaped or spicular crystals, which form little hexagons almost infinitely modified; and these again combining as they descend, produce flakes of snow. Some- times the frozen masses are very small, constituting sleet. At other times they assume the more formidable character of hail. " Hailstones are often of considerable dimensions, exceeding sometimes the length of an inch. They may, therefore, fall with a velocity of 70 feet per second, or at the rate of about 50 miles in the hour. Striking the ground with such impetuous force, it is easy to conceive the extensive injury which a hail-shower may occasion in the hotter climates. The destructive power of these missiles, in stripping and tearing the fruits and foliage, increases, besides, in a more rapid ratio than the momentum, and maybe estimated by the square of their velocity multiplied into their mass. This fatal energy is hence the fourth power of the diameter "of the hailstone."* 68. The celebrated Voha ascribed the formation of hail to elec- tricity, and proposed to defend tracts of country from hail-storms by rods on the principle of lightning conductors. These hail- rods or paragreles as they were called, were tried in France and Switzerland, but apparently with little advantage.f When is snow instead of rain the result of deposition of vapour? At what rate does the destructive energy of hail-stones increase with their diameter? On what two principles does Mr. Espy found his theory of aqueous de- positions ? (Note.') * Leslie on Heat and Moisture. t For an account of a terrific hail-storm, in which some of the masses weighed a pound each, see Commodore Porter's Letters from Constanti- nople. On the subject of rain, hail, snow, and water-spoiits, a very inge- nious theory has recently been advanced by Mr. James P. Espy, who refers the occurrence of these phenomena to the influence of the latent heat of vapour, given out in its condensation, acting as sensible heat on the atmospheric air, which, having a low specific heat, will be, in any given case, more expanded by the heat of the vapour which has been condensed, than it is contracted by the diminution of bulk, in the turning of that vapour to water. This increase of bulk in the air may occur when, satu- rated with vapour, it ascends from the surface of the earth in consequence of the diminution of its specific gravity a mixture of air and watery vapour being lighter, bulk for bulk, than pure atmospheric air. It is known that a mass of air, saturated with vapour, at any temperature, will deposit some portion of its vapour on being suddenly dilated in the receiver of an air-pump. In rising to the upper regions of air, the same result will be obtained, and the more decidedly the higher it rises, for the dilatation wiil be the greater as the height becomes more considerable. But though, by the dilatation, the vapour is condensed, yet the air which has parted with it does not contract and re-descend, for the latent heat given out is suffi- cient to keep its temperature above what it would have been had the same bulk of dry air been carried to the same height from the surface of the earth. Mr. Espy has found, by calculation, " that the quantity of latent caloric given out by the change of vapour to water or cloud, is sufficient to produce an expansion in the air six times greater than the contraction caused by the vapour turning to water." " This calculation is founded on three principles, which are all demonstrated by experiment. 1. The latent 460 METEOROLOGY. Dew, Hoar-frost, and Ground-ice. 69. The precipitations of water from the atmosphere, already described, depend on changes of temperature in the air; but there are others frequently taking place in consequence of depression of temperature in solid bodies. In the summer season, in clear, calm nights, the surface of the earth and growing plants are found at sun-rise covered with globules of limpid moisture, so that the trees and hedges glitter in the first rays of the sun, as if they were hung with multitudes of brilliant diamonds or transparent pearls. This phenomenon, so often described by poets as well as philosophers, and so familiarly known to all who inhabit the country, consti- tutes dew ; which, in some situations, occurs so copiously as to supply the want of rain. The circumstances under which it is precipitated, are so different from those which accompany the What is meant by dew ? heat of vapour is a constant quantity equal to 1212 of Fah. 2. The ca- pacity of atmospheric air is 25, that of water being 100. 3. The expansion of air by heat is l-480th of the whole, for every degree of Fah. above its bulk at 32." The result above stated leads to the conclusion, that the commencement of condensation in an ascending current of air will cause an expansion of the whole mass of air above the cloud, by keeping its temperature elevated, and causing it to rise and spread out in every direction above the cooler masses around it. Air, ascending into the upper regions of the atmosphere, is cooled one degree for each 100 yards of ascent. By rising 9000 yards, therefore, it would be cooled 90 degrees. But if air, saturated with vapour, should ascend to the same height, and should lose even 45 degrees of heat, it would deposit the greater part of its vapour in consequence of the rapidly diminished quantity of that substance capable of being suspended in the air at low temperatures. When much vapour is contained in the air at the surface of the earth, the latent heat from deposition would be more than sufficient to heat the air to 45 above the temperature due to dry air at the same height. The heated air will consequently continue to rise. The equilibrium, being thus once disturbed, cannot be restored while air highly charged with vapour exists at the surface of the earth. The pres- sure of the air, as indicated by the barometer, will be diminished beneath the cloud and, if it amount to one inch, may cause an ascending cur- rent of 230 feet per second " sufficient to carry up large drops of rain, after they are formed, far above the region of perpetual congelation," where they may be frozen and carried to the sides of the ascending cur- rent. When, at the commencement of the ascension, " the dew point is very high, and the ascending current very narrow, the upward velocity will be very great, and thus water-spouts, or what the French call trombes, both by sea and land, may be formed." The author supposes that " all the phenomena of rains, hails, snows and water-spouts, change of winds and depressions of the barometer, fol- low as easy and natural corollaries from the theory here advanced, that there is an expansion of the air containing transparent vapour, when that vapour is condensed into water" This theory is the result of much careful observation, and, as its author conceives, is justified by multitudes of facts, which meteorologists have not been able to solve on any other hypothesis. See Trans, of the Geol Soc. of Penn., vol. i., p. 342. ED. HOAR-FROST. 461 separation of moisture from the air in the state of rain, that philo- sophers were long at a loss to account for it. Among the causes as- signed for its production, one of the most plausible was electricity. 70. At length, however. Dr. W. C. Wells, by an ingeniously conducted series of experiments, ascertained that dew is chiefly owing to the radiation of heat from the substances on which it is deposited. Hence it is that dew never forms during nights which are both cloudy and windy ; and if, in the course of a night, the wea- ther from being serene should become dark and stormy, the dew which may have been produced will disappear. Grass, leaves of vegetables, or other bodies, must be quite exposed to the sky in order to enable them to receive dew ; and therefore the slightest shelter will prevent its deposition on the covered surface. The quantity of dew must necessarily depend, not entirely on the degree of radiation at any one time and place, but also on the amount of moisture present in the air. Perfect stillness in the atmosphere, therefore, is not always so favourable to the deposi- tion as gentle motion ; by means of which, after one mass of air has been deprived more or less of its moisture, by contact with radiating bodies, other portions of air, from which it has not been separated, may be successively brought near to those bodies, which may thus receive repeated deposits. Any considerable agitation, however, approaching to wind, causes the precipitation to cease. 71. These and many other circumstances, connected with the occurrence of dew, admit of a complete and lucid explanation, by referring them to the property of radiation. Light, fibrous sub- stances, as filaments of gossamer, wool, thread, cotton, hair, grass, and low plants, both dead and living, are among the best radiators, and receive dew most readily ; while rocks, bare earth, and considerable masses of water, have less disposition to part with their heat in the same manner, and therefore remain free from dew. 72. Hoar-frost is merely frozen dew, owing either to powerful radiation, when the atmosphere itself has a temperature above the freezing point, but the radiating substances part with their heat so fast as to fall below it, and thus the moisture freezes on them as soon as it is precipitated : or the congelation may be accom- plished and preserved by a depression of temperature in the air below 32 Fahrenheit. Glass is an excellent radiator of heat; and hence it often receives depositions of hoar-frost in winter, incrusting its surface sometimes with elegant frost-work, bearing To what is the deposition of dew at night chiefly attributable ? What is necessary, in regard to the situation of plants, in order that they should receive a deposit of dew ? What is the effect of motion in the air on the quantity of dew which it will deposit ? What character, in regard to emitting heat, have bodies which accumu- late much dew ? Why does glass accumulate hoar frost ? 2Q2 . 462 METEOROLOGY. a fanciful resemblance to trees and landscapes. Some of the sim- pler forms of hoar-frost are exhibited in the following figures. 73. The trees and hedges also in the cold season display yet more beautiful assemblages of snowy crystals, the complicated figures of which it would be useless to attempt to trace. Hoar- frost, in the -spring, sometimes destroys the buds and flowers of plants, and literally deprives the gardener of the fruit of his labour. It had been long known that tender vegetables and opening buds might be protected from its deposition by a very slight shelter ; but it is only since the discoveries of Dr. Wells have been pro- mulgated, that the manner in which such shelter acts (namely, by preventing radiation) has been properly understood. 74. The production of ground-ice, that is, ice formed at the bottom of rivers, is a phenomenon that has often attracted the no- tice of philosophers, and given rise to different hypotheses. Mr. T. A, Knight, in a paper published in the Philosophical Transac- tions, attributes the formation of ice in such situations to particles originally congealed at the surface, and afterwards carried to the bottom by the eddies of streams.* Neither this nor other theo- ries that have been advanced can be considered as satisfactory. The phenomena are well described in a paper by Mr. Richard Garnett, published in Brande's Journal of Science in 1818; but that gentleman does not propose any new mode of accounting for the existence of ground-ice. He remarks, however, that it never occurs but under peculiar atmospherical circumstances. f He adds, that " the immediate cause of the formation of this ice seems to be the rapid diminution of temperature in the stone or gravel in the bed of the river, (on which it is deposited,') connected with sudden changes in the state of the atmosphere."^ Why does a simple veil or screen, placed over plants, prevent their de- struction by frost? What is meant by ground-ice? What attempts have been made to explain its production? * See Abstracts of Papers in Philos. ^rans., vol. ii. p. 16. t Brande's Journal, vol. v., p. 269. t Idem, p. 273. V METEORITES. 463 5. Experiments, which could be best prosecuted in frosty weather, would be requisite to develop the cause of the formation, of ground-ice. It may, however, be not improbably attributed to the acquisition by stones or gravel, in consequence of radiation of heat, of a temperature below the freezing point, while the water passing over those substances was somewhat warmer. It may be stated, as an argument in favour of this supposition, that ground- ice is found only in clear, running water, through which it may be conceived radiation might take place.* 76. Various other atmospheric phenomena are frequently treated of in books relating to meteorology. These are chiefly of two classes, namely, those which may be explained by means of the laws of optics, and those which appear to depend on electro- magnetism. Among optical or photonomical phenomena, there are few more curious than the mirage, looming, and the fata morgana, or more beautiful than the rainbow ; and of these some notices will be found in the treatise on Optics, in the former vo- lume of this work. Notwithstanding the brilliant discoveries that have been made within the last forty or fifty years relative to electricity, we are yet by no means able to trace the full extent of its influence over the atmosphere. That it is the cause of light- ning is, however, universally admitted ; and to this subject the attention of the reader has been directed in the treatise on Elec- tricity. 77. Perhaps there are no atmospheric phenomena more singu- lar or problemetical than the descent of aerolites, or meteorites, as they have been termed. The fact of their fall was long doubted, but at present seems to be indisputably ascertained. They all consist chiefly of magnetic iron, having a remarkable analogy of composition. Their origin is quite uncertain ; and the different explanations of their appearance that have been attempted, are, perhaps, equally improbable. Some suppose them to have been formed in the air, an hypothesis which D'Aubuisson rejects as untenable ; others consider them as the products of volcanoes in the moon, projected into our atmosphere ; and, according to Chladni, they are fragments of planets which have burst in pieces amid the etherial space. What is the composition of aerolites or meteorites ? What hypotheses have been formed respecting them ? * This supposition seems, however, at variance with the generally re- ceived opinion, that water is but slightly, if at all, pervious to radiated heat. ED. 464 METEOROLOGY. Works on Meteorology. So many of the subjects connected with this department of science are still in an imperfect state, that no work which has hitherto fallen under our observation can be considered as abso- lutely free from error. Many detached memoirs and treatises of great value are extant, and we will present to the consideration of the reader such as appear likely to prove most satisfactory It is understood that the gentleman whose views of the causes of rain, hail, tornadoes, and water-spouts we have presented in a preceding page, is preparing for the press a work on his favourite department of study, in which those views will be carried out and applied to numerous phenomena connected with atmospheric changes. Daniell's Meteorological Essays and Observations. Dalton's Meteorological Observations and Essays. 1834. Leslie's Essays on Heat and Moisture. Front's Chemistry and Meteorology. Forbes on Meteorology, in the Report of the British Association for 1832. Pouillet Elemens de Phys. et de Meteorologie. 2 vols. Meteorological Register, from Observations made by the Sur- geons of the Army at the Military Posts of the United States. Washington. 1826. Nicolao Cacciatore de Redigendis ad unicam seriem compara- bilem Meteorologicis ubique Factis Observation ibus. Palermo. 1832. Article Hygrnmetry, in the Edinburgh Encyclopedia. Enclyclopedia Metropolitana, article Meteorology. Manuel de Meteorologie, par J. B. Felleus. Paris. 1833. Forster's Essays on Meteorology. INDEX. ABYMES DE MYANS, . p Action at various distances, 345 9 c Acid, ctfrbonic 21 perchloric, 81 oxiodic 82 bromic, . . . . 84 hydrofluoric, . silicofluoric, 85 86 muriatic, . 91 hydriodic, 93 hydrobromic, . hyponitrous, 94 98 nitric, . 9 carbonic, 103 prepared for ex- periments, 105 in geology, 325 107 mellitic, . 107 eroconic, . 107 hydrocyanic, . boracic, . 113 114 borofluoric, 116 117 silicofluoric, . 119 of phosphorus, . 121 hydrophosphoric, of sulphur, 125 126 anhydrous sulphuric, hyposulphurous, hyposulphuric, selenious and selenic, 128 128 129 133 hydroselenic, . sulphuric, in mineral wa- 134 ter, .... 180 arsenious, 275 Acids, general account of, . 6G terminology of, , 67 77 metallic, .... 134 Adhesiveness of minerals, . 242 Adits, how driven, 203 Aerolites, 463 Aerology, a department of che- mistry 11 Affinity, simple elective, . chemical, defined, 62 26 complex, 63 divellent and quiescent, Aggregation, attraction of, 64 9 Air, hot, in smelting furnaces, p. 223 modifies the earth's sur- face, . . 324 atmospheric, composition of, 96 gravity of, in meteorology, 439 Alkali, volatile, how composed, 19 Alcyonite, fossil, . . . 424 Albumen, 165 Alkalies are true metallic oxides, 67 in mineral water, . 179 Aluminum, compounds of, .115 oxides of, . . 258 properties of, . . 152 Alumina, in lime and magnesia, 163 Alloys, metallic, . . .230 table of, . . . 234, 235 Alum, crystals of, . . .284 Alluvial deposits, . . . 397 fossils in, . 428 Ammonia, how combined with muriatic acid, . 27 precipitates zinc from sulphuric acid, . 29 properties of, . . 100 Amalgams, .... 231 table of, . . . 235 Amorphous minerals, . . 242 Analcymee, .... 262 Anomalies of atomic weights, . 55 Animal substances exhale am- monia, . . . 101 fossils in submedial rocks, . . .410 kingdom, . . . 168 products, chemical, . 169 matter in soils, . . 176 how different from vegetable, 69 Animals introduced into mines, 194 Antimony, binary compounds of, 137 properties of, . .140 native, . . . 250 Antimonic oxide, . . . 268 Ynthracite, .... 251 Anthropophyllum, . . . 425 Anthropolites, . . . .432 Analysis, meaning of, . . 160 of vegetables, . .167 of soils, . . .172 Anticlinal axis .... 389 465 466 INDEX. Apparatus for decomposing wa- ter, . . p. 90 for burning diamonds, 104 Hare's, for boron, 115 Apophyllite 262 Aral lake, level of. . . . 32 Arrangement of bodies, chemical, 15 Arborizations, metallic, . . 45 on glass, . . 46 Arbor Dianae 45 Arragonite, .... 271 Arsenic, binary compounds of, properties of, localities of, compounds of, Arsenious acid, . Art of mining, . Artesian wells, temperature in, Asparagin, . Aspiration, winds, caused by, . Assays, mechanical, . by the dry method, in the moist way, . Attraction, two species of, chemical, . laws of, electric, affects che- mical combination, Atmosphere, temperature of, action of, on the earth, Atmospherical phenomena, Atom, chemical meaning of, Atomic weights, how expressed, must be found- ed on analy- sis, Aubert's experiments on sponta- neous combustion, . Aurum musivum, Auriferous silver, Avalanches, effects of, Aventurine, 137 139 . 196 . 250 . 275 . 19G 313 1G4 209 210 213 9 26 27 43 315 331 Bergmann's error explained, p. 63 Berthollet on decomposition, 63 Bertholi, spontaneous combus tionof, . 50 Berzelius' atomic weights, 56 view of all natura compounds, . 69 procured silicon, 116 classifications of bodies,136 discovered thorinum, 153 system of mineralogy, 244 Beudant's classification of mine- rals, 245, Beithraupt on pearly lustre, Binary compounds of metals, Birdlime Bittern the source of bromine, Bihydroguret of phosphorus, Bisulphuret of hydrogen, . 440 Bismuth, compounds of, . 245 239 137 166 83 125 130 155 158 195 248 254 25" 165 431 64 102 252 375 438 Blowpipe, action of, . .211, 212 52, Body, human, combustible ma- properties of, localities of, native, sulphuret of, oxide of, Bitter principle, Bize bone caverns, Black's diagram of affinity, Black, ivory, . Blende, .... Blocks, erratic, 56 Axinite 267 Azote, properties of, . . . 18 Bagnes, lake of, burst, . . 242 Baku, fine temples at, Balsams, 166 Baryum, compounds of, . . 145 properties of, . . 149 Barometric height at London, Barytes, bromate of, . . 84 native sulphate of, . 278 Bases, double, . . . 66 chemical, . . 67 Basin shaped strata, . . 388 Basilosaurus, . . . 426 Basalt, . . . 384 Bergmann on decompositions, . 62 te rials in 51 Bodies, simple, . , . .69 Bohon upas, .... 326 Boulders, whence derived, . 375 Books on chemistry, . . . 185 metallurgy, . 235 mineralogy, . . 282 crystallography, . . 297 geology, . . .397 oryctology, . . 435 meteorology, . . 464 Bone caverns, .... 428 Bones human in caverns, . . 31 Boron, . . . . .113 binary compounds of, . 72 fluorides of, . . . 87 chlorides of, . .116 Boracic acid in mineral water, 180 439 Borates, 270 Bovey coal 401 Bovista giganteum, . . .31 Brocken, section of the, . . 392 Brohlthal, carbonic acid of, . 326 Bromine, nature of, . . . 23 properties of, . . 83 compounds of, . . 83 atomic weight of, . 85 INDEX. 467 Brewster on ignition of pJatina, p. 37 Bromide of sulphur, . . . 131 Bubbles, soap, thickness of their film, . . . . .31 Butter of antimony, . . . 144 Cadmium, binary compounds of, 154 properties of, Calcium fluorides of, . chloride of, compounds of, properties of, Calcining furnace, Calcareous spar, rocks formed under the sea, Camphor, Candescent state of the earth, . Caoutchouc, . Carbon, combining volume of, . binary compounds of, . particular properties of, conducts electricity, . Celestine Cemeteries of Dunwich sul merged, .... Cerium, binary compounds of, Cerite, properties of, Cerithium giganteum, Cementation, Chamisso on corals, . 85 Chamelion mineral, 131 Charcoal, spontaneous combus- 145| tion of, . >.277 . 350 . 154 . 157 . 261 . 426 . 224 . 355 . 143 35 150 Changes of the earth's surface, 369 hange of properties by combi- 272 354 166 299 166 58 71 101 102 108 109 131 21 electricity protochloride of, . iodide of, . sulphuret of, found separate, and carburets, as mine- rals, . . . .250 Carbonates decompose insoluble salts, ; . .66 in mineral waters, . 179 mineral, . . . 271 isomorphic, . . 286 Carbonic acid in the atmosphere, 96 properties of, . 103 in mineral waters, 177 in the earth, . 325 11 110 Carbo-hydrogen, Faraday's, Carburet of hydrogen, Carbonate of lime, precipitated from lakes, . of soda, . . . 353 Carbonaceous matter in fossil Carboniferous group, . . . 394 Carnivorous animals, in bone caverns, 42 Carrara marble, . . . 27S Cafmine, colouring power of, . 31 Caspian sea, level of, . . 322 Cassini on the temperature of nation, .... 12 "hemistry defined, ... 9 science of, how com- pleted, . . .13 Chemical action in combustion and respiration, . 13 attraction, laws of, 27, 28 . 463 . 83 . 159 native, . . . 280 as primary compounds, 67 of potassa " oxygen, . of nitrogen, cobalt, . bromine, . sulphur, . aluminum, Chladni's theory of aerolites, Chloridic acid, . Chlorides of mercury Chloride furnishes 74 99 143 85 131 152 20 20 20, 78 ydrate of, . . . 81 binary compounds of, 70 with hydrogen, . . 92 Chloropheite, . . . .261 Chlorine supports combustion, used in bleaching, properties of, h\ Chromates, Chrome, binary compounds of, properties of, localities of, Cipolin, 269, 270 138 141 196 273 stems, 416 Circumstances influence affinity, 61 Cirrus cloud, Clues Mary, spontaneous com- bustion of, .... Claromont, spontaneous combus tion described by, . Classification of metals, of minerals, . [Cleavage of crystals, the earth, .... 309 Cassius, powder of, . . . 144|Climate of the oolitic period, Cast iron, kinds of, . . 224;Clouds, remarks on, Casts of medals from mineral de- formation of, . posits, 273 1 height of, Cawk, a mineral gangue, . . 190| constitution of, Cavendish discovered hydrogen, 87i modifications of 454 48 50 136 244 289 419 450 451 452 453 453 468 INDEX. Cloud of day, . . . o. 455 of night, . . . .456 Coal, .... 282 Copper, protected from corrosion by zinc, . . p. 44 binary compounds of, . 154 properties of, . . 158 localities of, . . .194 analysis of, . . . 214 ores, reduction of, . 226 alloys of, ... 233 native, .... 247 sulphurets of, . . 253 native oxides of, . . 257 carbonate of, . 275 phosphate of, . 276 Coral reefs, formation of, . . 355 Cornelian, 260 Uornean, 384 Cordier on the temperature of the earth, .... 310 Cosmogony, system of, . . 298 Cotton, chemical nature of, . 166 Cretaceous group, . . . 390 Dri d'etain, .... 144 Crinoidal fossil animals, . .411 ^roconic acid, .... 107 Cross courses, .... 192 measures, fossils in, . . 4K Bovey, .... 401 Cobalt, binary compounds of, . 13i properties of, . . . 143 chloride of, . . .143 localities of, . . .195 Cobalt, sulphurets of, . . 253 glance, . . . .256 oxides of, ... 257 arseniates of, . . 275 Codfish, spawn of, . . 32 Coins impressed on plastic sul- phur, 126 Colours, vegetable, affected by charcoal, . . .132 of minerals, . . . 238 Colum bates, .... 268 Columbium, binary compounds -of, . . . 137 properties of, . . 140 Colebrook's theory of the earth's density, 306 Columnar rocks, Comet, Encke's, retarded by the 390 ether, Composition, attraction of, molecular, Combining numbers of salts, Combustion, a chemical process, supported by iodine, facts relating to, . spontaneous, . spontaneous, of the human body, 38. 48. 50 supported by oxy- Cryptogamic plants, seeds of, transported through the air, 316 Crystals, various forms of, simple, in fossils, Crystallography, purpose of, 331 242 290 405 283 1 3 " works relating to, 297 23 Cumulus cloud, . . . 455 34 Cumulostratus 457 35 Cupellation, . . . .217 Cuvier's discoveries in orycto- logy, 302 Cyanogen, . . . . .112 gen, Como, lake of, filled by detritus, 344 Compounds differ f^om their con- stituents, . . 26 of gases become so- lids, ... 27 primary and second- ary 75 Daniell's melting point of silver, 135 illustration of the dew- point, . . . 449 | Davy's method of protecting cop- per, . .45 66 safety lamp, Days, length of the, affected by 110 of metallic elements, 144; the cooling of the earth, ".312 Datolite, 271 Compression of carbonic acid, . 106jDiallage rock, . . . 382 of the earth at the | Dichroite, 265 poles, Compressibility of air and water, 307 Condor of the Andes, Conductors and non-conductors of electricity, Conformable rocks, Consistency of minerals, Continents, elevation of, Contortions of strata, . Copper, dissolved by sulphuric acid, 307 438 25 387 241 378 386 28 Dip of strata, .... 389 Discoveries of modern philoso- phers, 13 Districts, mining, why barren, . 198 Disthene, 261 Diamond, an isolated body, . 14 chemical nature of, . 102 apparatus for combus- tion of, . . .104 variable hardness in, . 240 INDEX. 469 Diamond, remarkable specimens Elements, four, of the ancients, p. 15 of, .p. 250 seven, of the alchy- Divisibility of matter and of mists, . . .15 * t\f* sixty-four of the mo- Deads in mineral veins, . . 189 derns, . . .15 Decomposition, double, . . 64 metallic and non-me- Deinotherium, .... 428 tallic, . 1G Density, a means of distinguish- ing bodies, . .14 list of, - . , .18 Elie de Beaumont on mountains, 319 in minerals, . . . 241 Encke's comet, how retarded, . 316 Denudation of surfaces, . . 373 Encrinites, 399 Depth of mineral veins, . . 189 Deposits, alluvial, . . . 428 Epsom salts, crystals of, . . 284 Epidote in mineralogy, . . 264 Dew, theory of, . . . . 461 Equivalents, chemical scale of, 57 Dew-point, nature of the, . . 449 Erie, lake, may be emptied, 337. 342 method of ascertaining, 450 Erratic blocks, .... 375 Docimasy, ..... 209 Eruptions and earthquakes, . 358 Doebereiner's discoveries on Espy on hail-storms and torna- spongy platina, . . .36 dos, . . . . .459 Dolomieu on carbonic acid, . 325 Etesian wind, .... 445 Drusy cavities, .... 408 Expansion, rate of, in moisture, . 446 Dulong on decomposition, . . 66 Dunwich cliffs, degradation of, 349 Farquharson's account of a flood Dyke, in geology, . . . 389 in the Don 339 Fault in rocks, .... 389 Earfh, figure of, . . . .304 mean density of, . . 306 Faraday reduced gases to liquids, 10 Feldspar, .... 262, 263 temperature of, . . 308 Fermentation, .... 170 consolidation of, from fu- Ferns, fossil, . . . 403. 418 sion, . . . .311 Fibrous hygrometers, . 447 Earthquakes, geological effects of, 357' Fibrin, *~ 165 frequency of, . 358; Final's cave, .... 390 in Chili, . 359 Fire-damp 109 Earths are metallic oxides, . 67 Fire of, oxidation and reduction, 212 analysis of, . . 161 Flint, 260 primary, in minerals, . 161 Floatage, power of, in the air, . 332 Echinite, 424 Flowers of sulphur, . . .126 Electricity, chemical effects of, 40 fossil 404 by evaporation and Fluate of alumina and soda, na- . , solution, . . 4] tive 280 opposite states of, in Fluorine, general account of, . 23 combining bodies, 47 the cause of combus- particular properties of, 85 Fluor spar, . . . .85 tion, . . .47 crystalline forms of, 292 in spontaneous com- Fluoride of silver, ... 86 bustion of the hu- ofboroni ... 87 man body, . . 47 Fluorides, native, . . . 279 of minerals, . . 241 Fontinelle on spontaneous com- Electric light from animals, . 48 bustion 50 action on the earth's Forms of bodies classed, . . 10 surface, . . .368 Formations, general view of, . 322 Electro-positive bodies, with hy- Fourier on the temperature of drogen, . . . .94 celestial spaces, . . . 317 Electro-chemical relations of mi- Fossil flowers, .... 404 nerals, 24 vegetables, sections of, . 417 Electro-positive native metals, 246 shells, . . . .417 Electro-negative metals, . . 249 theorv of, . 299 Elephant, fossil, in Russia, . 429 Franklin's discovery on north- Elevation of mountains, . . 373 east storms, . . . 441 of chalk strata, . . 378 Freind's remarks on crystals, . 284 2R 470 INDEX. Fuel for smelting, Fundamental rocks, Furnace, calcining, . Fusion, igneous, of the earth, Gahn's blowpipe, Galena, .... Garnet, family of minerals, Gases combined by electricity, atomic constitution of, evolved from volcanos, p. 222, 223jGrenier, mount, fall of, . p. 344 . 387iGrenough on elevation of conti- 226 nents, 379 318 Greenstone rock, . . . 382 Groups of formations, . .320 21 1 synoptical arrangement of, 393 254 carboniferous, . . . 393 264 penean, . . . .394 40 keupric, .... 395 91 liasic, . . . . 394 328 inflammable from fisssures in the earth, . . 329 Gas, intoxicating, . . .97 olefiant, . . . .111 Gangue of minerals, 190 Gay Lussac's instantaneous light, 37 on combining volumes, 58 Gehlenite, 265 Gelatin, characters of, . . 165 Gensanne on the heat of mines, 310 Geognostic epochs, . . . 406 Geology, purpose of, . . . 298 of the United States, . 433 Geological Society, influence of, 301 arrangement of mine- rals and fossils, . 405 Geysers contain silica, . .118 temperature of, . . 313 deposit of, . . . 351 Giant's causeway, . . " . 390 Gilding, water, .... 230 Glacial phosphoric acid, . .122 Glass, etching on, by fluoric acid, 86 composition of, . .118 Glance cobalt, .... 256 Glauber's salt, crystals of, . . 284 Glucinum, binary compounds of, 145 properties of, . .153 Gluten, 165 . 14 . 31 . 83 . 155 . 159 Ground-ice, Gum, 462 164 166 Gun-barrel for decomposing water, 90 Gypsum, deposits of, . Hading of mineral veins, . Hair hygrometer, imperfect, Hail-stones, momentum of, Hail-storms, theory of, Hardness of minerals, Haiiy, simple forms discovered by, 290 Haiiy's system of mineralogy, . 244 researches in crystallo- graphy, . . .288 theory, objections to, . 293 Haworih, mud deluge at, . . 346 Hay-ricks, combustion of, . . 36 Heat, expansive power of, . 9 evolved by burning bodies, 33 and light in combustion, . 76 of the earth, Fourier on, . 317 Gold, an isolated body, malleability of, . acted on by iodic acid, binary compounds of, chemical nature of, test of, ..... 213 native, .... 249 localities of, . . .193 Goniometers, .... 295 Gossan, in mineral veins, . . 202 Granite, disintegration of. by air, . . . 327. 336 variable characters of, 381 supposed universal, . 392 Gravities, specific, of gasses and vapours, .- 60 of iodine, . 82 Graphite, 251 Grauwacke, .... 383 Great Staple Tor, . . .327 . 353 188 448 459 460 409 Hare's mode of procuring boron, 114 Harmotome mineral, . . 262 Harmattan wind, 445 Heaving of mineral veins, 191 Henry, Prof., on Niagara gorge, 337 Hisingerite, .... 261 Hoar-frost, 461 Horn iomorph ism, . . . 287 Homberg's sedative salt, . . 113 Hornstone mineral, . . . 259 Horsburgh on descending cur- rents of air, . . . . 442 Hot air blast, how applied, . 223 Howard's classification of clouds, 454 Human body, combustion of, . 38 bones, fossil, . . . 354 Hurricanes, geological effects of, 334 Hutton's theory of the earth, . 300 of coal formations, 413 81 19 37 54 55 59 Hydrate of chlorine, Hydrogen, general account of, reacts with platina, and sulphur, atomic weight of, volume of, binary compounds of, 76 peculiar properties of, 87 mode of obtaining, . 87 INDEX 471 Hydrogen, protoxide of, . p. 88 fas ffGncrator 89 ron, cast and wrought, . p. 224 native, .... 247 eutoxide ol', . . 91 native, oxides of, . . 256 employed to inflame tungstate of, ... 269 diamond, . .105 native, carbonates of, . . 274 phosphuretted, . . 124 oxalate of, . . . . 281 sulphuretted, . . 129 Islands produced by submarine in water, . . .178 volcanos,- . . . 366 bisulphuret of, . .130 destruction of, . . 349 Hydrofluoric acid, ... 94 'somerism, 123 Hydrochloric acid, . . .91 Isomorphism, . . . .123 Hydrobromic acid, . . .94 Hydrochloride of carbon, . .111 Hydrothionic acid, . . . 129 Jasper, varieties of, . . . 260 Junction, line of, in strata, . 434 Hydroselenic acid, . . . 134 Hydriodic acid 93 Kamsin wind, .... 445 Hygrometry, .... 446 Keupric group of rocks, . . 395 Hygroscopes, .... 447 Hylffiosaurus, .... 423 Kibble in a mine shaft, . . 204 Kirkdale bone caverns, . . 430 Hyponitrous acid, . . .98 Kremnitz mine described, . 200 Hypophosphorous acid, . . 122 Hyposulphurous acid, . . 126 Krokydalite, . . . .264 Hyposulphuric acid, . . . 12 Lampblack, nature of, . . 102 Land and water, relative extent Ice, ground, .... 462 of, .... . 319 melted in ammoniacal gas, 101 Landslips, how caused, . 344 Ichthyosaurus, .... 422 Lapis lazuli, . . . 266 Igneous origin of rocks, . . 40 Latiolite, ... . 266 Impulsion, winds caused by, . 44C Lauder's account of the Moray Incompatible salts, . . . 184 deluge, ... . 338 Increments of crystals, . . 28i Laumontite, . . . 262 Intoxicating gas, . , .97 Indigo, chemical nature of, . l&l Inulin, 164 Lava cut through by water, . 336 Lavoisier on composition of acids; 66 Laws of chemical attraction, . 27 Instruments for analysis, . .175 Iodine, general nature of, . . 2J Lead tree, 46 oxides of, . . . .55 binary compounds of, . 7] peculiar properties of, . 81 binary compounds of, . 154 chemical properties of, . 158 solution of, in water, . I localities of, ... 194 compounds of, with chlo- effect of, in alloys, . . 233 rine, . . . .81 lodic acid, 82 sulphurets of, . . . 254 native oxides of, . . 257 Iodide of nitrogen, . . . 10( carbonates of, . 274 carbon, . . .109 arseniate of, . . 275 phosphorus, . . 1& Leaves, fossil, .... 402 Iridium, binary compounds of, . 15( Lehman's division of rock properties of, . . 16( strata 300, 391 Iron precipitates copper from so- lution, . . . .28 protected from corrosion by Leibnitz' theory of the earth, . 299 Lemery's remarks on crystals, . 285 Lepidodendron, . . .*-'. 418 zinc, . . . .4' Leslie on compressibility of mat- wire, burnt in oxygen gas, 7J ter, 307 binary compounds of, Ifr Lias rock, 383 properties of, . . 156 Liasic group, .... 395 how detected in minera Light in combustion, whence de- analyses, . . . 162 rived, 76 in mineral water, . 18C Liquor, silicum, . . . .118 localities of, . . 195 Lisbon, earthquake at, . . 359 assay of, in the moist way, 214 ores, reduction of, . . 221 Lithium, binary compounds of, 145 properties of, . . 148 472 INDEX. Lily encrinite, . Lime, precipitation by, properties of, p. 419]Metals, native, phosphates of, p. 276 . 29 sulphates of, . 279 . 150 1 Metallic salts, how decomposed, 46 how separated from baryta, 164 1 acids, .... 134 in mineral waters, . . 181 [Metamerism, .... 123 native, sulphate of, . . 278 Metallurgy, . . . .186 secreted by corals, . . 357 books on, . . 235 Limestone, mountain, fossils in, 413 Metallursric chemistry, 214 Lode of a mine, . . . . 202 Meteoric stones, ".' . .247 Lustre of minerals, . . . 239 Meteorology, definition of, . 436 Lybian desert, sands, moveable works on, . . 464 in, ... . . .333 Meudon crocodile, . . . 425 Lycopodium, section of, . . 418 Micaceous minerals, . . . 263 Mines, 186 Maclure's view of the geology depth of, . . . . 205 of America, .... 434 Mineralogy, objects of, . . 236 Madrepores, . . . -400 works on, . . 282 Madreporite, .... 412 Mineral kingdom, ingredients in, 69 Manganese, oxide of, . 74, 266 chameleon, . . . 143 with salt produces deposits, . . . 186 chlorine, . . 78 veins 188 binary compounds of, 139 waters, .... 176 properties of, . . 142 localities of, . .196 ingredients in, . 177 analysis of, . 178 Mantell's discoveries of fossils, 376 Minerals, assaying of, . . 209 Magnesia, aluminate of, . . 258 how distinguished, . 237 native carbonate of, . 274 physical characters of, 238 sulphate of, . . 278 constituents of, . . 243 Magnesium, compounds of, . 145 classification of, . . 244 properties of, . .151 classes of, . . .246 Marbles, 272 composing rocks, . 380 Maskeleyne on the earth's den- artificially formed, . 408 sity, 306 Mining, art of, . . . .196 Matrix of a mineral, . . . 190 system of, in South Ame- Matter, divisibility of, . 30, 31 Mechanical mixture, . . 11 rica, . . . .201 Minuteness of molecules, . . 29 Medial rocks, . . . 394, 412 Mississippi, cut offs in the, . 347 Megalonyx, .... 424 Mitscherlich on isomorphism, . 286 Megatherium, .... 431 Mixture, mechanical, . . 12 Mellate of alumina, . . . 281 effect of, on compound Mellitic acid 107 bodies, . . .61 Menachan ore, .... 268 Moisture in the air, by what in- Melting-pots, for zinc ore, . . 229 fluenced, ... 96 Melting-point of metals, . . 135 quantity of, in the of potassium, . 146 air, . . . 446, 450 Mercury, affected by tempera- Moh's improvement in crystallo- tures, . . . 38 graphy, . . .296 binary compounds of, 155 Molecules, minuteness of, . . 29 properties of, . . 159 of lead, weight of, . 33 localities of, . . 194 self-repulsive, . . 59 ores of, how reduced, 220 Molybdenum, binary compounds native, . . . 248 of, . . . 138 sulphnret of, . . 254 properties of, . 141 Metals, great variety of, . . 24 Molybdates, . . . .269 extensive use of, . . 25 Monas gelatinosa, . . 32 electro-negative, not. cor- Moray, deluge at, . , . 338 roded, . . . .44 melting-point of, . . 135 three classes of, . . 136 Motion, rotatory of the earth, . 312 Monsoons, how explained, . 444 in primordial rocks, . 408 Mountain limestone, . *!T . 399 INDEX. 473 Mountains, height of, compared with the earth's diameter, . p. 320 volcanic, . . .361 elevation of, . . 373 Ore, silver, how reduced, . p. 218 Ores of lead, assayed in the hu- mid way, . . . 214 of gold, reduction of, 216, 217 of zinc, reduced, . . 229 Mud, deluge of, . . . .346 Multiples in combining atoms, . 53 Muriatic acid, . . . .91 in mineral waters, 180 Muriates in mineral waters, 182, 183 Naphthaline, . . . .111 Native iron, .... 247 Naumann's views of mineral forms 296 Navir, grind of the, . . .348 Neptunists, . . . .301 Neufchatel, lake, described by Saussure, . . . .343 Neutral primary compounds, 66. 68 New Jersey, denudations in, . 377 Niagara, detrition at, . . 336 falling of rocks at, . 342 Nickel, compounds of, . .154 properties of, . . .157 localities of, . . . 196 copper, .... 247 sulphurets of, . . 253 Nimbus, 457 Nitrates, 277 Organo-chemical substances, Organic remains in the United States, . Oryctology, purpose of, works on, Osseous breccias Outlying rocks, Oxalate of iron, Oxalic acid, Oxacids, . . Oxides, metallic, and acids, of chlorine, of electro-positive me- tals, . Oxide, nitrous, .... carbonic, . of phosphorus, . Oxygen, general account of, evolved at the positive pole, .... combining weight of, . mode of generating, peculiar properties of . absorbed by melted sil- ver, . combinations of, with sulphur, binary compounds of, . Palladium, binary compounds of, . properties of, . Panean group, . Particles, magnitude of, Paragreles of Volta, . Paris observatory, caves of the, Palseotherium maximum, . Peacock, Mrs., combustion of, . Pechblende, . Pelissy's theory of fossils, . Penzance mine, Pentremites, . 281 433 398 435 431 389 281 107 67 25 77 80 256 98 103 120 18 42 53 73 74 218 126 156 155 160 394 9 459 309 427 49 257 299 206 411 420 10 128 406 208 80 232 27* Nitre, crystalline form of, . . 285 Nitrogen, general account of, . 18 the base of nitric acid, 18 combines with oxygen, 53 binary compounds of, 71 particular properties of, 95 compounds of, with oxygen, . . .96 protoxide of, . . 97 chloride of, . . 99 Nitrous acid, . . . .98 Nodules in geology, . . . 391 Nomenclature of acids and salts, 77 Notch in the White mountains, 342 Nucleus, primary, of crystals, . 288 Ocean, bottom of, how shaped, 319 Octaedrons from cubic mole- cules, 294 Ochre, uran, . . . .257 Oil of heaven, . . . .168 Oils, fixed and volatile, . . 65 Old women, combustion of, . 51 Olefiantgas, . . . .111 Oolite, 273 Pentacrinite, Briarean, Permanent gases reduced to li- quids, . . . . Perchloride of phosphorus, Periods, geological, . Persian process for silver, . Peroxide of chlorine, Pewter, composition of, Phosphates, native, . . Phosphorus, general account ^ r combustio^ Oolitic group, fossils in, Opal, Ore veins of, how discovered, silver how assayed, . . 419 . 260 . 197 . 214 2R2 474 INDEX. Phosphorus, spontaneous com- bustion of, . i binary compounds o inflames in bromine, in nitrous oxide, peculiar properties of, . . . oxide of, bottles, how made, iodide of, sulphuret of, . Phosphoric acid, weight of, character of, . Phosphuret of carbon, Phosphuretted hydrogen, . Pharmacopolite, . ... Picture, sympathetic, Pinite, Pisolite, . . . ,.36 ;72 84 97 119 120 121 124 132 7f> 121 125 124 275 13G 262 273 345 384 425 86 155 160 193 220 249 287 422 251 291 279 123 356 382 12 29 145 107 134 144 201 ii 144 439 29 262 66 98 407 135 291 77 Process, metallurgic, . . . p. 215 Protochloride of carbon, . . 108 selenium, . 133 phosphorus, . 123 Protectors, Davy's, . . .45 Protoxide of chlorine, . . 79 hydrogen, . . 88 nitrogen, . . 97 iron, . . . 157 Prout on equivalent volumes, . 59 Pyrites, 253 Pyrophosphoric acid, . . . 122 Pyrophysalite, .... 267 Pyrometer, steam, . . .135 Pyromorphiie, .... 275 Putty, tin, 144 Quartz, varieties of, . . . 259 Rain, causes of, . . . . 457 quantity of, in different re- Pitz mountain, fall of, Pitchstone, Plagiostoma dumosum, Platina, fluorides of, . binary compounds of, . properties of, localities of, . reduction of, . 219, native, .... Plesiomorphism, Plesiosaurus, .... Plumbago, Polyedra in crystallography, Polyhalite, Polymerism, .... Polypifers, singular power of, . Porphyritic rocks, Potash and tartaric acid combine, precipitates lime, Potassium, ..... decomposes carbonic acid, melting-point of, binary compounds of, Potosi, silver mines at, Powder, of various colours, sepa- rable after mixture, . ofcassius, Pressure, variations of, Precipitation, . . . x Prehnite Primary compounds,three classes of, Priestley discovered nitric oxide, Primordial rocks, . 323.393. Prinsep's experiments on fusion, Prisms in crystallography, . Products of combustion, Ratios, combining, anomalous, . 54 Ravenna, site of, changed, . 340 Reagents for analysis, . . 173 Reduction of iron ores, . . 221 tin ores, . . 225 copper ores, . . 228 lead, . . .228 zinc, . . .229 Reefs, coral, .... 355 Relics, human, pretended, . 432 Remains, organic, by whom stu- died, . . .302 fossil, in the wealden group, . . .423 Resins, 166 Respiration, a chemical process, 13 supported by oxygen, 74 Revolutions in the condition of the earth, . . . 303 Rhodium, binary compounds of, 156 properties of, . . 160 Richter on combining quantities, 68 River, Yellow, of China, . .340 Roasting of iron ore, . . . 221 Robinson on effects of rivers, . 339 Rock crystal, . . 259 milk, 274 Rocks, disintegration of, . 335 structure and composition of, .... 380 how important in geology, 381 non-fossiliferous, . . 382 texture of, ... 385 submedial, formations of, 393 medial, . . . .412 Proportions, definite, . 52 Rodolphus mine at Kremnitz, . 200 INDEX. 475 Rome Delisle on crystals, p. 288 equality of an gles in crys- tals, . . 295 Rossberg, fall of, . . . 345 Roubaudi's remarks on marine exhalations, .... 330 Ruby silver, 256 Silver, fluoride of, Saddle-shaped strata, Safety lamp, Davy's, . Sal-ammoniac, .... Salt, common, primary nucleus of, . crystals of, . . 284 lakes, . . . Salts, combining numbers of, with names in ate and tie, 77 incompatible in mineral waters, . . . 184 soluble and insoluble, . 68 Sand hills, how formed, . . 333 floods, . . . . 333 pillars of, moved by winds, 445 Sandstone, texture. of, . . 383 -Snrc^coll, 164 Saturated air deposits moisture on being mixed, . . . 447 Saurian animals in supermedial rocks 421 melting-point of, . binary compounds of, chemical properties of, . localities of, . absorbs oxygen when melted, native, . sulphuret of, . ruby pits of the North sea, Simple bodies, . . . . Simoom wind, . . . . 2SO Sirocco wind p. 86 135 155 159 193 Skorodite, 352jSlag of lead ore, how used, 68 Smelting of iron, Saussure on Neufchatel lake, . 343 Saussure's hygrometer, . . 448 Schorls, . . . . .266 Sea, mine under the, . . 206 formative effects of the, . 353 barriers formed by the, . 369 breezes, how explained, . 444 Selenium, general account of, . 24 binary compounds of, 73 peculiar properties of, 132 in mineralogy, . . 257 Selenious and selenic acid, . 133 Separation, line of, in strata, . 387 Serpentine mineral, . . . 264 rocks, Shale, Shafts, sinking of, Shap granite, Shocks of earthquakes, Silica, how obtained pure, and silicates, . Silex in mineral waters, . Sillimanite, Silicic acid, Silicon, general nature of, binary compounds of, peculiar properties of, chloride of, . Silico-fluoric acid, . 218 . 248 . 255 . 256 . 321 . 69 . 445 . 445 . 275 . 228 . 222 Snow-flakes under a microscope, 283 Snow, theory of, Soda, sulphate of, in mineral 459 181 266 144 147 . 148 . 280 . 170 . 171 172. 175 . 173 . 235 . 11 . 39 215 . 39 . 346 . 346 . 169 . 85 Spawn of codfish, minuteness of, 32 33 water, Sodalite, Sodium, binary compounds of, properties of, . melting-point of, . chloride of, . . Soils, nature of, . . . productiveness of, . analysis of, . moisture in, .. Solders, table of, .. Solidity, supposed cause of, Solution effected by heat, . of metals, how tested, Solvent power, table of, . Solway moss, mud deluge at, p, Sonccbos landsl Spallanzani, on carbonic acid, Spar, fluor Specific heat of compounds, gravity of muriatic acid, 92 Spontaneous combustion, cause of, 51 382iStalactitic limestone, . . . 272 . 383, Staple Tor, Great, . . .327 . 202J Starch 165 . 375, a test of iodine, . . 82 . 360| States of bodies depend on heat, 10 . 117 : Steam pyrometer, . . . J35 258. 261 j engines in mines, . .204 . 181 Steel, nature of, 224 .2611 different kinds of, . .225 . 117 Stilbite, 262 21 1 Stones, analysis of, . . .107 72 Strata, contorted, . . 386, 387 116| coal, how disposed, .387 119! volcanic, . . .395 86 j Stratified rocks, . . . .385 476 INDEX. Stratum, invariable, . p. 308 Stratus cloud, . . 455 Stromboli, eruptions of, 362 Strontian, compounds of, 145 properties of, 150 Strontianite, . . 271 Strobilus, fossil, . . . 402 Temperature, elevated, promotes chemical action, p. 38 increasing, of the lower terrestrial strata, . . 309 of mines, . . 310 mean, of different zones, . . 312 of lakes and seas, . 315 of celestial spaces, 316 Temperaments of animals, . 438 Temples, fire, .... 328 Subcarburet of hydrogen, . 109 Submedial rocks, . 397. 409 Subchloride of carbon, . 108 Suber, ... .166 Substances composing the earth's crust, 70 Sugar, chemical properties of, . 164 Sulphate of barytes, how decom- posed, . . .65 of potash, combining weight of, . . 69 Sulphates in mineral waters, . 181 mineral, . . 277-279 Sulphur, general account of, . 22 electric state of, . . 43 binary compounds of, . 72 burns in oxygen, . 75 and iron filings decom- pose air, . . .97 decomposes carburet of hydrogen, . .110 peculiar properties of, 126 acids of, . . .127 chloride of, . . .131 bromide of, . . . 131 and sulphurets, . . 252 Sulphuret of carbon, . . 131 of phosphorus, . .132 Sulphurets, composite, . . 255 Sulphuretted hydrogen, . 129, 130 Sump in a mine, . . . 204 Superincumbent rocks, . . 387 Supermedial rocks, . . . 394 fossils in, . 419 Superior rocks, .... 396 Syenite rock, .... 382 Systems, mineralogical, . . 237 Swinestone, .... 273 Table of mineral constituents, . 243 classes, . . 246 of vapours, . . 60 of gases, . . 61 Talcose minerals, . . 263 Tantalite, . . 268 Tannin, . . 165 Taper extinguished by carbonic acid, . . 106 Taste of minerals, . . .241 Telluri um, binary com pounds of, 1 38 properties of, . . 141 ores of, . . 249 Terra pond erosa, . . . 149 Tertiary rocks, fossils in, . . 426 Tesseral system of minerals, ." 297 Testing of mineral waters, . 177 Texture of rocks, . . . 385 Tides, during the igneous fusion of the earth, .... 318 Tilgate forest, fossils of, . . 423 Time, measured by geological periods, ..... 370 Tin, oxide of, .... 258 pyrites 254 binary compounds of, . . 139- putty 144 properties of, . . . 143 localities of, . . .194 ores, how reduced, . . 225 grain or stream, . . . 226 Tincroft mine, section of, . . 191 Tinstone, where found, . . 187 Tinning of copper vessels, . 232 Titanium, binary compounds of.-. . . . . . 137 properties of, . . 140 oxides of, . . . 267 Thorinum, compounds of, . . 145 properties of, . .153 Thermal springs, deposits from, 351 Toad's-eye woad tin, . . . 258 Tomboro, eruption of, . 333. 363 Topaz minerals, . . . 267 Tornados, .... 335. 445 Trachite, 384 Trade winds 443 Transition limestone, . . 383 Transparency of minerals, . 239 Trap rocks 384 Traptuff, 384 Travertin, deposits of, . 351 Tremolite, isomorphic, with an- thophyllite, . . . .287 Trilobites 410 Triplite . . . 276 Trombus, 445 Trough-shaped strata, . . 388 Truncation of crystals, . . 292 INDEX. 477 Trunks of trees found in quar- ries, . . . p. 4 Tungsten, compounds of, . .1. properties of, . . Tungstates, . . . .26 Turner on atomic weights, Turquois of Khorasan, . .27 Tyfong, phenomena attending the 44 Ulmin 16 Unconfbrmable rocks, . . 38 Unit, molecular, of Prout, . . 6 Upheaving of mountains, . . 37 Uranium, binary compounds of, 13 properties of, . . 14 oxide of, . . 25*" Upas valley, in Java, . . 32 Uspalta silver vein, . . .19 Vanadium, binary compounds of, 17f properties of, . . 14 and vanadiates, . 27( Valleys, how formed, . .34 excavation of, . . 37 Vapour of bromine, . . .8, Variable winds beyond the trades, 44' Vegetable kingdom, . . . 16<; analysis, . . . 167 matter in soils, . 17( Vegeto-alkalies, . . .167 Vegetables, constituents of, . 167 fossil, in coal, . . 41 intimate components of, ... 69 living, emit oxygen, 74 Veins, intersection of, . .191 Vibrio, minuteness of the, . . 3S Volatile ingredients in minerals, 162 Volcanic eruption at St. Vincents, 331 strata, . . . .397 Volcanos, quantity of matter ejected by, . . 365 submarine, . . 365 causes of, . . . 367 products of, . . 385 geological relations of, 357 extent and number of, 361 intermitting, . . 382 Voltaic pile, a chemical imple- ment, 41 Volumes combining, . . 57 Vulcanists, followers of Hutton, 301 Wacke 384 Washita hot springs, . . .351 Water decomposed by galva- nism, . . . 42. 99 atomic constitution of, . 53 anar fire-spring, Water, composition of, proved synthetically, . . 88 composition of, proved analytically, . . 89 absorbs carbonic acid, . 106 mineral, carbonated, . 106 general account of, 176 evaporated from the sea, 330 geological effects of, . 336 of rivers extends into the ocean, unmixed, . . 340 motion of, over the British islands, . . 376 spouts, theory of, . 459 absorbs chlorine, . 79 weight of, in a cubic inch of air, . . . 446 Waves degrade the land, . 348 Wax, .... .165 Wealden group of rocks, . 395 Vedging out of mineral veins, 187 Weights, atomic, of different bo- dies, . . . .53 of water in a cubic inch of air, . . .446 Weiss and Mohs on mineral classification, .... 297 Veld ing of iron, . . . 156 Veils, on the causes of dew, . 461 Wenzell on chemical affinities, 68 (Verner's system of mineralogy, 244 theory of the earth, . 300 division of rocks, .391 Vheal ferry, . . . .208 Vhirlwinds, . . . .445 Vhite mountains, . . . 341 Vinds, causes of, ... 440 proceed to windward, . 441 velocity of, how estimated, 445 /Vollaston's theory of atmo- spheric limits, 32. 437 scale of equivalents, 57 theory of crystalliza- tion, . . .294 goniometer, . . 296 Vollastonite, .... 261 Vood, chemical nature of, . 166 fossilized, . . .401 Vorks, list of, on chemistry, . 185 metallurgy, . 235 mineralogy, . 282 crystallography,297 geology, . . 397 oryctology, . 435 meteorology, . 464 necessary for mining ope- rations, . . . 199 . 329 478 INDEX. Yttrium, compounds of, . p. 141 properties of, . .153 Zangari, countess, spontaneous combustion of, ... 48 Zinc precipitates iron, . . 28 binary compounds of, . 154 Zinc, properties of, localities of, oxides of, . silicate of, . Zirconium, compounds of, properties of, Zirconite, . ; >. 157 195 257 267 45 152 261 THE END. * VALUABLE SCHOOL-BOOKS PUBLISHED BY KEY & BIDDLE. PINNOCK'S ENGLAND. THIRD AMERICAN, FROM THE TWENTY-THIRD LONDON EDITION. PINNOCK'S IMPROVED EDITION OF DR. GOLD- SMITH'S HISTORY OF ENGLAND, from the Inva- sion of Julius Caesar to the death of George II., with a continuation to the year 1832 : with Questions for exa- mination at the end of each section ; besides a variety of valuable information added throughout the work, consist- ing of Tables of Contemporary Sovereigns and Eminent Persons, copious Explanatory Notes, Remarks on the Politics, Manners, and Literature of the Age, and an Out- line of the Constitution. Illustrated with Thirty En- gravings on Wood. Third American, corrected and re- vised from the Twenty-third English Edition. RECOMMENDATIONS. MESSRS. KEY & BIDDLE, Philadelphia, Oct. 20, 1834. Gentlemen Be pleased to accept my thanks for the favour you have done me in sending a copy of your neat and attractive edition of Pinnock's Goldsmith's England. It appears to me to have been sedu- lously prepared for the purpose which it professes to subserve that of a convenient manual for schools and academies. By the questions and tabular views at the ends of the several chapters, the scholar will be able to test his own acquisitions, and to embrace at a glance an im- k portant collection of facts, in regard to the history and biography of the period of which he has been reading. These land-marks for the me- mory serve to raise a host of reminiscences, all interesting to the dili- gent and inquiring student. With my wishes for the success of the work, accept the assurances of the high respect with which I sub* scribe myself, Your obedient servant, WALTER R. JOHNSON, Professor of Mechanics and Natural Philosophy in the Franklin Institute. [2] From S. JONES, A. M. Principal of the Classical and Mathematical Institute, Philadelphia. I have attentively examined Pinnock's improved edition of Dr Goldsmith's History of England, published by Messrs. Key & Biddle, of this city, and am impressed with its excellence. I have no hesita- tion in expressing my full approbation of the work, with my belief that it will receive a liberal patronage from an enlightened community. UthMo: 1834. I consider Pinnock's edition of Goldsmith's History of England as the best edition of that work which has yet been published for the use of schools. The tables of contemporary sovereigns and eminent persons, at the end of each chapter, afford the means of many useful remarks and comparisons with the history of other nations. With these views, I cheerfully recommend it as a book well adapted to school purposes. JOHN M. KEAGY. Friends' Academy, Philadelphia. We fully concur in the opinion as expressed above. SETH SMITH, WM. A. GARRIGUES, J. H. BLACK, M. SOULE, THOS. COLLINS, REV. CHAS. HENRY ALDEN, JAMES CROVVELL, JOHN EUSTACE, J. B. WALKER. BENJ. C. TUCKER, S. C. WALKER, HUGH MORROW, T. H. WILSON. WM. McNAIN, J. MADEIRA. E. H. HUBBARD. WM. MANN, R. LAKE, W. MARRIOTT, JOHN WEBB, C. B. TREGO, JOHN ORD. / URIAH KITCHEN. SAML. CLENDENIN. THOS. EUSTACE, I). R. ASHTON. JOHN IIASLAM. J. O'CONOR, Scc'y to the Phila. W. CURRAN, Association of Teachers. J. STOCKUALE, JOSEPH WARREN, S. II. REEVES, THOMAS CONRAD, J. HAYMAR, THOS. McADAM, W. B. ROSE, REV. SAML. W. CRAWFORD, CHAS. MEAD, A. M. Principal of Acadl. Dept BENJ. MAYO, of University of Pennsylvania. REV. S. M. GAYLEY, Wil- M. L. HURLBUT, mington, Del. R. W. CUSHMAN, E. FOUSE, AUGUSTINE LUDINGTON, J. E. SLACK, JOHN ERHARDT, JOSEPH R. EASTBURN, OLIVER A. SHAW, A. STEVENSON, A. D. CLEVELAND. Baltimore, Dec. 1&34. We fully concur in the opinion above expressed. SAML. JONES, WILLIAM HAMILTON. O. W. TREADWELL. JOS. WALKER, E. BENNETT, JAMES SHANIJSY, E. R. HARNEY, DAVID RING, ROBT. O'NEILL, ROBT. WALKER, N. SPELMAN, D. W. B. McCLELAN, S. W. ROSZELL, S. A. DAVIS, SAMUEL HUBBELL, JAS. F. GOULD, H. O. WATTS, JOSH. H. CLARKE, C. F. BANSEMER, FRANCIS WATERS, D. E. REESE, JOHN MAGEE, S. A. CLARKE, MIC1IL. POWER. JOHN FINLEY A. M. [3 ] New York, Dec. 183*. We fully concur in the opinion above expressed. W. R. ADDINGTON, THOMAS GILDERSLIEVE, BERNARD THORNTON, MELANCTHON HOYT, SIIEPPAKD JOHNSTON. THOMAS V. FOWLER, HORACE COVELL, J. BAILE, P. PERRINE, SAMUEL GARDNER, J. B. KIDDER, G. VALE, SOLOMON JENNER. J. TAFT. JOSEPH M'KEEN, JOSIAII J. UNDERIIILL. EZRA MUNDY. C. W. NICHOLS, C. CARTER, THOMAS M'KEE, LEONARD HAZELTINF, G. J. HORRER, JOSEPH CHAMBERLAIN. N. DUNN, HENRY SWORDS. R. TOB1TT, J. M. ELY, SAMUEL BROWN, W. M. SOMERVILLE, ADN. HEGEMAN, NORTON THAYER, WILLIAM FORREST. Gentlemen I have looked (but without effect, till now) for a reading- book combining at once interest, chasteness of diction, and valuable histo- rical information, placed in so enticing a form as to induce the student to read it for itself and the fac^s it. contains. My long experience has taught me, that, without interest, the pupil will not trouble himself to understand; and without understanding, 'tis in vain to teach, either for improvement in the science of reading or for information. Happily, teachers have in Pin nock's Goldsmith's History of England numerous requisites unknown to the best of its predecessors. Yours. L. BICKNELL. Philadelphia, Nov. 1834. We fully concur in the above. WM. ROBERTS. B. N. LEWIS. MESSRS. KEY & BTODLB, November 21, 1834. Gentlemen 1 have been much pleased by the perusal of "Pinnock's im- proved edition of Dr. Goldsmith's History of England." I think it fully en- titled to the appellation, improved, and should rejoice to see it placed in the hands of all our American youth. That you, gentlemen, may meet with that encouragement which efforts to supply the wants of our schools merit, is the desire of Yours, &c. J. H. BROWN, Principal of the English and Mathematical Academy, No. 52 Cherry-street, Philad. Review of " Pinnock's Goldsmith's England," made at the request, and for the use of the Lyceum of Teachers of the city of Philadelphia , by J. H. Brown, Principal of Classical Academy, 52 Cherry-street. PINNOCK'S IMPROVED EDITION OF DR. GOLDSMITH'S HISTOR1 OF ENGLAND, illustrated by thirty Engravings on wood. The first American, corrected and revised from the 23d English edition, pp. 453. Philad. Key & Biddle, 1834. THERE is no history, except our own, which is of so much interest to us as that of England ; and probably no history of England, designed for the use of schools, has been so popular as that of Dr. Goldsmith. And yet Teachers have long felt the want of some work that should remedy many defects which are found in it. Mr. Pinnock has continued the history to the year 1832, with the addition of " questions for examination," at the end of each section ; the latter, I am aware, will be received by some teachers as of doubtful utility; yet the judicious teacher, by viewing the questions merely as hints to himself, will so vary them, as to avoid the too common error of neglecting the section for the question. A more important addi- tion is the tables of contemporary sovereigns and eminent persons, with [4 J copious explanatory notes, and remarks on the politics, manners, and litera ture of the age. So far as the original work of Dr. Goldsmith is preserved, I shall not presume to speak. The notes above alluded to are valuable additions to the original work; and happily interspersed. The remarks on politics, manners, and literature, though judiciously made, fall short in amount of what many would consider proper for an interesting a'nd instruc- tive history ; yet, as this part, if much extended, would be dull and spiritless to the young, (for whom the work is chiefly intended,) perhaps the author has pursued the best course. The style is animated and clear, abounding sufficiently in anecdote to make it interesting to the young, and may be considered the most interest- ing history of England (for the use of schools) extant. (Signed) J. H. BROWN, Principal of Academy, 52 Cherry-st. GUY ON ASTRONOMY, AND KEITH ON THE GLOBES. THIRTEENTH EDITION. GUY'S ELEMENTS OF ASTRONOMY, AND AN ABRIDGEMENT OF KEITH'S NEW TREATISE ON THE GLOBE S. Thirteenth American edition, with additions and improvements, and an explanation of the Astronomical part of the American Almanac. Illustrated with eighteen plates, drawn and engraved on steel, in the best manner. RECOMMENDATIONS. A volume containing Guy's popular treatise of Astronomy* and Keith on the Globes, having been submitted to us for examination, and care- fully examined, we can without any hesitation recommend it to the notice and patronage of parents and teachers. The work on astronomy is clear, intelligible, and suited to the comprehension of young per- sons. It comprises a great amount of information, and is well illustrated with steel engravings Keith on the Globes has long been recognised as a standard schoov-book. The present edition, comprised in the same volume with the Astronomy, is improved by the omission of much extraneous matter, and the reduction of size and price. On the whole, we know of no schooil-book which comprises so much in so little space as the new edition of Guy and Keith, THOS. EUSTACE, W. B. ROSE. JOHN IIASLAM, CHAS. MEAD, W. CURRAN. BENJ. MAYO, SAML. CLENDENIN, HUGH MORROW. S. H. REEVES, J. H. BLACK, JOHN STOCKDALE, S. C. WALKER, [53 J. B. WALKER. J. E. SLACK, JOSEPH R. EASTBURN, WM. McNAIN, H. O. WATTS, J. O'CONOR, Secretary to the Phila. Association of Teachers. B. N. LEWIS. REV. CHAS. H. ALDEN. BENJ. C. TUCKER, J. H. BROWN, JOHN ORD, SETII SMITH, WM. ROBERTS, T. H. WILSON, JOSEPH WARREN, TIIOS. COLLINS, WM. MANN, RIAL LAKE, W. MARRIOTT, C. B. TREGO, JOHN ERHARDT, R. W. CUSHMAN. THO3. McADAM, REV. SAML. W. CRAWFORD Principal of Acadl. Dept. of the University of Pennsylvania. O. A. SHAW, AUGUSTINE LUDINGTON M. SOULE, WM. A. GARRIGUES. M. L. HURLBUT. Baltimore, Dec. 1834. We fully concur in the opinion above expressed. E. BENNETT, C. F. BANSEMAR, E. R. HARNEY, ROBT. O'NEIIA, N. SPELMAN, S. W. ROSZELL, SAMUEL IIUBBELL, D. E. REESE, S. A. CLARKE, JOS. WALKER, O. W. TREADWELL, REV. S. M. GAYLEY, Wil- mington, Del. JAMES SHANLEY, DAVID RING, ROBT. WALKER, D. W. B. McCLELAN, S. A. DAVIS, JAS. F. GOULD, JOS. H. CLARKE, A. M. FRANCIS WATERS, JOHN MAGEE, MICHL. POWER, C. D. CLEVELAND. Willbraham, Oct. 27, 1834. We have used Guy's Astronomy, and Keith on the Globes, as a text-book, during the past year ; it is in all respects such an one as was wanted, and we have no disposition to exchange it for any other with which we are acquainted. WM. G. MITCHELL, Lecturer on the Natural Sciences and Astronomy, in Wesleyan Academy, Mass, New York, Dec. 1834. We fully concur in the opinion above expressed. BERNARD THORNTON, W. M. SOMERVILLE, HORACE COVELL, P. PERRINE, J. B. KIDDER, SOLOMON JENNER, JOSEPH M'KEEN. C. CARTER, NORTON THAYER, THOMAS GILDERSLIEVE, MELANCTHON HOYT, THOMAS V. FOWLER- JOSEPH BAILE, SAMUEL GARDNER, LEONARD HAZELTINE, WILLIAM FORREST, JOSEPH CHAMBERLAIN, C. W. NICHOLS, W. R. ADDINGTON, THOMAS M'KEE, HENRY SWORDS, ADN. HEGEMAN. J. M. ELY, G. VALE. A3 en BRIDGE'S ALGEBRA. A TREATISE ON THE ELEMENTS OF ALGE BRA. By Rev. B. Bridge, D.D. F.R.S., Fellow of St, Peter's College, Cambridge, and late Professor of Ma thematics in the East India College, Herts. Revised and corrected from the eighth London edition. RECOMMENDATIONS. In this work the hitherto abstract and difficult science of Algebra is .rimplified and illustrated so as to be attainable by the younger class of learners, and by those who have riot the aid of a teacher. It is al- ready introduced into the University of Pennsylvania, at Philadel- phia; and the Western University at Pittsburg. It is also the text- book of Gummere's School at Burlington, and Friends' College at Hayerford, and of a great number of the best schools throughout the United States. It is equally adapted to common schools and colleges. Philadelphia, March 1th, 1833. Bridge's Algebra is the text-book in the school under my care; and I am better pleased with it than with any which I have heretofore used. The author is very clear in his explanations, and systematic in nis arrangement, and has succeeded in rendering a comparatively ab- struse branch of science, an agreeable and interesting exercise both to pupil and teacher. JOHN FROST. We fully concur in the opinion above expressed. CHAS. HENRY ALDEN, JOSEPH WARREN, J. O'CONOR, Secretary to SAML. CLENDENIN, the Phila. Association of S. H. REEVES. Teachers. GENTLEMEN In you my opinion respecting leave to say, that the work appears to be well adapted to the instruct tion of students. The arrangement of the several parts of the science is judicious, and the examples are numerous and well selected. Yours, respectfully, ROBERT ADRAIN. We fully concur in the opinion of Bridge's Algebra as expressed by Dr. Adrain. J. HAYMER, B. N. LEWIS, HUGH MORROW. JOHN STOCKDALE, WM. McNAIN, W. B. ROSE. OLIVER A. SHAW. BENJ. MAYO, SETH SMITH, J. H. BLACK. SAML. E. JONES, THOS. McADAM, JNO. M. KEAGY, REV. SAML. W. CRAWFORD, THOMAS CONRAD, Principal of Acadl. Dept. of the THOS. COLLINS, University of Pennsylvania. J. E. SLACK, JOHN ERHARDT, C. B. TREGO, R. W. CUSHMAN, J. B. WALKER, REV. S. M. GAYLEY, Wilming JOHN HASLAM, ton, Del. W. CURRAN, Baltimore, Dec. 1834. We fully concur in the opinion above expressed. E. BENNETT. O. W. TREADWELL E. R. IIAUNEY, JOS. WALKER, ROBT. O'NEILL. DAVID RING, N. SPELMAN, ROBT. WALKER, S. W. ROSZELL, D. W. McCLELAN, SAMUEL HUBBELL, S. A. DAVIS, H. O. WATTS, JOS. H. CLARKE, A.M. C. F. BANSEMER, FRANCIS WATERS, D. E. REESE, JOHN MAGEE, S. A. CLARKE, MICHL. POWER. MESSRS. KEY & BIDDLE, November 22, 1834. Gentlemen I have be'en highly gratified by an examination of " Bridge's Algebra," published by you; and think it well entitled to general introduction in our schools. I shall give it a preference in my academy to any work I have seen. Respectfully, yours, J. tf. BROWN, Principal of an English and Mathematical Academy, No. 52 Cherry-street, Philadelphia. New York, Dec. 1834. We fully concur in the opinion above expressed. P. PEKRINE, NORTON THAYER, . J. B. KIDDER, THOMAS GILDERSLIEVE, SOLOMON JENNER. MELANCTHON HOYT, JOSEPH M'KEEN. THOMAS V. FOWLER, C. CARTER, JOSEPH BAILE, LEONARD HAZELTINE, SAMUEL GARDNER, W. R. ADDINGTON, C. W. NICHOLS, HENRY SWORDS, THOMAS M'KEE. W. M. SOMERVILLE, TO TEACHERS OF FRENCH. L'ABEILLE- POUR LES ENFANS, ou Lecons Fran- Daises, lere Partie ; a 1'usage des ecoles. Several compilations of short and interesting French tales have been lately- offered to the public. In all of them, however, expressions are found, which, although familiar to the ear of a Frenchman, offend that of a care- fully educated American child. It is true that the French do not consider "Mon Dieu !" swearing; with them, it, is equivalent to "Gracious!" or "Oh, dear!" but it is certainly desirable that the eye and the ear of the pupils of schools in this country should not become accustomed to such ex- pressions. They have therefore been carefully excluded from this little work, as well as every thing of an unchristian tendency. It is designed for the first reading book. The style is simple, the sentences short, and con- taining few idioms, inversions, or difficulties. At the end of each page is a translation of the idiomatic expressions it contains, and of the words used in an acceptation not given in the dictionary. IN PRESS, The following new and valuable works for Schools and Academws, PINNOCK'S IMPROVED EDITION OF DR. GOLDSMITH'S HISTORY OF GRKECE, revised corrected and very considerably [8] enlarged, by the addition of several new chapters and numerous use- ful notes, with questions for examination, at the end of each section Revised from the twelfth London edition, with thirty engravings, by A therton. PINNOCK'S IMPROVED EDITION OF DR. GOLDSMITH'S HISTORY OF ROME, to which is prefixed an Introduction "*& the study of Roman history, and a great variety of information throughout the work, on the Manners, Institutions, and Antiquities of the Romans, with questions for examination, at the end of each section. Revised from the twelfth London edition, with additions and improvements, with thirty engravings, by Atherton. HISTORY OF THE UNITED STATES. K. & B. have in prepa- ration such a History of the United States as has been long and loudly called for by Teachers and Parents. It will be written by a gentleman very favourably known as an historian, who is eminently capable of making a book that will, in every respect, satisfy the wants of the public. The style of getting up will be the same as Pin- nock's Goldsmith's England, which, the publishers are happy to say, has met wiih the decided approbation of Teachers and Parents. SACRED HISTORY OF THE DELUGE, illustrated and cor- roborated by evidences derived from tradition, mythology, and ge- ology ; adapted to courses of Scripti>re Study, in colleges and higher seminaries, and to general use, by Francis Fellowes, A. M., with an Introductory Essay on the Study of the Scriptures as a part of liberal education. By the Rev. Chauncey Colton, A. M., President of Bristol College. A FAMILIAR INTRODUCTION TO THE PRINCIPLES OF NATURAL PHILOSOPHY, adapted to the use of schools. Part I comprising Mechanics, Hydraulics, Hydrostatics, Pneumatics, Acous tics, Pyronomics, Optics, Electricity, Galvanism, Magnetism. With notes, references, questions for examination, and a copious index, by Walter R. Johnson, Professor of Mechanics and Natural Philosophy in the Franklin Institute of the State of Pennsylvania. A FAMILIAR INTRODUCTION TO THE PRINCIPLES OF NATURAL PHILOSOPHY, adapted to the use of schools. Part 2, comprising Chemistry, Metallurgy, Mineralogy, Chrystallography, Ge- ology, Oryctollogy, and Meteorology. With notes, references, ques- tions for examination, and a copious index, by Walter R. Johnson, Professor of Mechanics and Natural Philosophy in the Franklin In- stitute of the State of Pennsylvania. MANUAL OF CLASSICAL LITERATURE, from the German of John J. Eschenburg. With additions, by Professor Fiske of Am- herst College. The work comprises four parts: 1. The Archaeology of Greek and Roman Literature and Art. 2. The Greek and Roman Classic Authors. 3- The Greek and Roman Mythology. 4. The Greek and Roman Antiquities. AN ETYMOLOGICAL DICTIONARY OF THE ENGLISH LANGUAGE, on a plan entirely new, by John Oswald. Revised and improved, and especially adapted to the purpose of teaching English Composition in schools and academies, by J. M. Keagy. THE SCIENTIFIC CLASS-BOOK THE SCIENTIFIC CLASS-BOOK ; OR, A FAMILIAR IN- TRODUCTION TO THE PRINCIPLES OF PHYSICAL SCIENCE, for the use of Schools and Academies, on the basid of Mr. J. M. Moffat. Part I. Comprising Mechanics, Hydrosta- tics, Hydraulics, Pneumatics, Acoustics, Pyronomics, Optics, Electricity, Galvanism, Magnetism. With Emendations, Notes, Questions for Examination, List of Works for Reference, some additional Illustrations, and an Index. By Walter R. Johnson, A.M., Professor of Mechanics and Natural Philosophy in the Franklin Institute of the State of Pennsylvania, Member of the Academy of Natural Sciences of Philadelphia, one of the Vice-Presidents of the American Institute of Instruction. MESSRS. KEY & BIDDLE, Philadelphia, June 22, 1835. I have carefully examined your "Scientific Class-Book, Part I." and find it what has for some time been much wanted in our academies and high schools. The emendations, notes, and additional illustrations, are important, and what might be expected from one so perfectly at home, both theore- tically and practically, in the range of Natural Philosophy, as Mr. Johnson is extensively known to be. The list of works for reference will be appre- ciated by intelligent teachers. I have introduced it as a Text- Book, and commend it cordially to the notice and examination of others. CHARLES HENRY ALDEN, Principal of the Philadelphia High School for Young Ladies. I fully concur in the above. SAMUEL JONES. Philadelphia, June 1 ^, 1835. I fully concur with Messrs. Frost, Keagy, and Jones, in their opinion of Mr. Johnson's work on Natural Philosophy, and shall immediately adopt the book as the best I know of for use in my own and other schools, in this city. in which I give instruction. OLIVER A. SHAW. We have examined Mr. Johnson's Scientific Class-Book, and are so well satisfied with its merits, that we shall adopt it as a class-book on Natural Philosophy in our school. S. C. & J. B. WALKER. MESSRS. KEY & BIDDLE, Philadelphia, June 26, 1835. A careful examination of the treatise on Mechanical Philosophy, entitled "The Scientific Class-Book, Part I." has satisfied me, that it is by far the most complete class-book, on that subject, which has yet fallen under my notice. The additions made by Professor Johnson, particularly the bibli- ographical notes, are not less creditable to his learning and sound judgment, than conducive to the utility of the work for the purposes of instruction. The volume may be safely recommended as a standard class-book for schools and private students. JOHN FROST. MESSRS. KEY & BIDDLE, Gentlemen: It is with much pleasure that I have examined "The Sci- entific Class-Book," on the basis of J. M. Moffat, Esq., by Walter R. John- son, A.M. It is such a work as the advancing state of education in this eountry particularly demands at the present time. I hope its use may fcecome general. With regard, yours, J. H. BROWN. [10] MESSRS. KEY & BIDDLE, Gentlemen : I have to thank you for a copy of the Scientific Class-Book, prepared by Professor Johnson, from the work of MofFat. 1 have been so interested in the perusal of it, that I feel almost incapacitated to speak criti- cally of its character: and yet this interest, perhaps, may speak its highest praiso. The exhibition of truth, in such a manner as to allure and reward attention with delight, even where the charm of novelty is wanting, is cer- tainly a rare merit in an elementary treatise on the Natural Sciences. The Scientific Class-Book, however, is very far from being made up of stale categories. It embraces a surprising amount of information respecting the most recent discoveries information which will not be found in any other single work whatever. I would cordially recommend it as a book admirably adapted, by its fulness and simplicity, by its happy comuination of scientific accuracy, with a charming narrative sort of ease, at once to awaken the love of knowledge and to impart it It will prove a most valuable work to our higher schools and academies, and to the teachers of all others. Yours, truly, R. W. CUSHMAN. MESSRS. KEY & BIDDLE, 6th Month 23d, 1835. Gentlemen: I have examined the first part of the Scientific Class-Book iust published by you, and cheerfully express my opinion, that, for accuracy and comprehensiveness, this work contains a system of principles and illus- trations on the subject on which it treats, superior to any book of the same size and price intended for the use of schools. As this volume is the first of a series on the Mechanical and Physical Sciences, the public may confidently expect that the successive parts, when completed, will constitute a consistent set of treatises peculiarly adapted to the present wants of places of education. JOHN M. KEAGY. We cheerfully concur in opinion with the above recommendations. JOS. P. ENGLE3, WILLIAM MARRIOTT, HUGH MORROW, RIAL LAKE, WM. A. GARRIGUES. BENJ. MAYO, M. SO1TLE. JAMES P. ESPY, JACOB PEIRCE, REV. SAML. W. CRAWFORD, A.M., BENJ'N C. TUCKER, Principal of the Acadl. Dept. of th T. G. POTTS, University of Pennsylvania, WM. CURRAN, THOS. M. ADAM, S. BICKNELL, CHARLES MEAD, D. R. ASHTON, JAS. E. SLACK, EL. FOUSE, L. W. BURNET, C. FELTT, WM. MANN, A. M. THOS. BALDWIN, CHAS. B. TREGO. JOHN STOCKDALE, WM. ROBERTS, URIAH KITCHEN, THOS. COLLINS, THOS. H. WILSON, SAML. CLENDENIN, SHEPHERD A. REEVES, AUGUSTINE LUDINGTON, E. H. HUBBARD, JNO. D. GRISCOM, WILLIAM McNAIR, N. DODGE, JAMES CROWELL, JOHN HASLAM. J. O'CONNOR, New York, July, 1835. Having examined the First Part of the Scientific Class-Book, we feel jus- tified in concurring in the above favourable recommendations. EDW. D. BARRY, DAVID SCHUPER, J. M. ELY, F. A. STREETER, JOSEPH McKEEN, CHARLES W. NICHOLS, JONATHAN B. K I ODER, THOMAS McKEE, PATRICK S. CASSADY, G. I. HOPPER, WM. R. ADDINGTON, J. B. PECK, RUFUS LOCKWOOD, S. JENNER. NORTON THAYER. RICHARD J. SMITH. JOHN OAKLEY, [11] From Alexander D. Bache, A.M., Professor of Natural Philosophy and Chemistry, University of Pennsylvania. MESSRS. KEY & BIDDLB, Gentlemen : I have examined, with much pleasure, the first part of the "Scientific Class- Book." The additions of the American editor appear to me to have well adapted the book for use in schools and academies. Its utility to the general reader has no doubt been increased by the same labours. Very respectfully, yours, September 16, 1835. A. D. BACHE. From S. Jones, A.M., Principal of Mathematical and Classical Institute. I regard "Guy's Elements of Astronomy," and "Keith on the Globes," as the best book of the kind which 1 have examined, and feel a confidence that the price of the work, the beautiful and appropriate illustrations, and the handsome and correct manner in which the treatises have been exe- cuted by the publishers and editor, as well as their intrinsic merit, will commend them to every parent and teacher. Philadelphia, July 21, 1835. S. JONES. We cordially concur in the recommendation of Messrs. Key & Blddle's edition of Guy and Keith. REV. DAVID R. AUSTIN, A.M., Principal of Monson Academy, Monson, Mass., September 21, 1835. T. L. WRIGHT, Principal of East Hartford Classical and English School, East Hartford, September 23, 1S35. From Simeon Hart,jun., A.M., for several years Principal of Farming- ton Academy, Connecticut. MESSRS. KEY & BIDDLE, I have examined, with considerable attention, " Bridge's Treatise on the Elements of Algebra," and am so favourably impressed with its excellence, that I have introduced it into my school as one of the text-books to be used by students in algebra. I have also examined, with much pleasure, "the Scientific Class-Book, or a familiar Introduction to the Principles of Physical Science," and would say, in the words of the closing paragraph of the preface, "that whatever merit may be claimed for other treatises on the same departments in science, this, it is confidently anticipated, will be found to embrace as full and satis- factory a view of the subjects on which it treats, as any similar compilation which has hitherto been dedicated to the service of American youth." An examination of "Guy's Astronomy," and "Keith on the Globes," has resulted in the conviction, that they may be safely recommended to parents and teachers as works well calculated to interest and instruct the intelli- gent scholar. Pinnock's improved edition of Dr. Goldsmith's "Abridgment of the His- tory of Rome," and his improved edition of the " History of England," are works which need only to be known to be admired, as well adapted to the wants of schools and academies in this country. Respectfully yours, SIMEON HART, JtJN. Farmington, Conn., September 4, 1835. From Rev. Dr. Cornelius D. Westbrook, Principal of a Female School, New Brunswick, New Jersey. I have examined Pinnock's improved edition of Dr. Goldsmith's " History of England," by Key & Biddle of Philadelphia, and I do most cheerfully recommend it to teachers of schools and academies as the best arrano' ment of that very popular school book I have ever seep New Brunswick, August 1, 1835 [12] ;-, I most cordially join with Dr. Westbrook in his opinion of Pinnock's Goldsmith's England. REV. DAVID R. AUSTIN, A.M., Principal of Monson Academy ', Monson, Mass., September 21, 1835. From T. L. Wright, A.M., Principal of East Hartford Classical and English School. I very cheerfully concur with S. Jones, A.M., Principal of the Classical and Mathematical Institute, relative to " Pinnock's England ;" and with Dr. Adrain in his opinion expressed of 7 " Bridge's Algebra." " Pinnock's Rome," I regard as well adapted to the use of schools and private reading. East Hartford, September 23, 1835. from Rev. C. D. Westbrook, D.D., Teacher, New Jersey. I have examined Key & Biddle's edition of "Guy's Elements of Astro- nomy," and "An Abridgment of Keith's Treatise on the Globes." Keith on the use of the globes is too well known to need any recommendation ; and " Guy's Astronomy" will recommend itself to any one who wishes to introduce to his scholars, or to his children, the interesting and sublime study of astronomy. CORNELIUS D. WESTBROOK. New Brunswick, August 1, 1835. FromN. W. Fiske, A.M., V.D.M., Professor, Amherst College, Mass. MESSRS. KEY & BIDDLE, Gentlemen . With great satisfaction, I have examined your editions of " Pinnock's Goldsmith's Rome" and "England." They are executed in a very convenient and attractive form, and are works which may be confi- dently recommended for use in all our schools and academies. The "Scientific Class- Book" appears to me, judging from the portions I have yet found time to read, a very excellent work. A vast amount of the most interesting and valuable knowledge is brought into a small compass, and is generally presented in a very clear and happy method. I hope it will obtain extensive circulation, as I know of nothing better adapted for common instruction in the sciences which are treated in the part I have seen. Very respectfully, I am yours, September 21, 1835. N. W. FISKE. In the opinion expressed by Professor Fiske, respecting the " Scientific Class-Book, Part I." I can most cheerfully concur. E. S. SNELL, A.M., Professor of Mathematics and Natural Philosophy, in Amherst College, Massachusetts. From Rev. David R. Austin, A.M., Principal of Monson Academy. I fully agree with Professors Fiske and Snell, in regard to the " Scientifi Class Book," and shall adopt it in the institution of which I have the charge D. R. AUSTIN. I concur with Professor Fiske, and numerous others, in relation to " Pin nock's Rome." D. R. AUSTIN. Monson, September 23, 1835. SamuelJones, A.M., of Philadelphia, says of Bridge's Algebra: "Th lucid style of investigating subjects pursued by Professor Bridge in his 'Conic Sections,' and other works, is found commenced here : the arrange- ment is methodical and good, and I can unhesitatingly recommend it as well worthy of the places of the ill-digested compilations used in many schools." We cordially join with Mr. Jones in his opinion of Key & Biddle's edition of "Bridge's Algebra." H. S. AUSTIN. J. M. MOORE, J. CROWLEY, A.B. [13] I can unhesitatingly subscribe to the numerous commendations of " Bridge's Algebra." DAVID R. AUSTIN, Principal of Monson Academy, Massachusetts, The New Jersey Journal, printed August 25, 1835, at Elizabethtown, N. J., remarks of all these works : "To be appreciated, these books require only to be known. We most cordially recommend them to teachers and parents. As long as their enter- prising publishers publish such books, and in such taste, they cannot fail to meet with encouragement." FromJ. G. De Soter, M.A., Professor of French, Spanish, and Italian, Philadelphia. 1 have examined "L'Abeille pour les Enfans," published by Messrs. Key and Biddle of this city, and am so much pleased with the pure and chaste style of the selection, that I shall use it in my instruction with the younger pupils. J. G. DE SOTER. Rev. S. North, A.M., Professor of Languages, Hamilton College, writes to the publishers of these Histories : "After an attentive examination of Goldsmith's Histories of Rome and England, with notes and other additions by Pinnock, it gives me pleasure to say, that I think them the best editions of those deservedly popular works which have yet been published." He adds also " From a cursory exami- nation of 'Bridge's Algebra,' 'The Scientific Class-Book,' and 'Guy's As- tronomy,' they appear to me to be well fitted to facilitate the progress of students in the respective sciences of which they treat." Clinton, Oneida Co., N. Y., September 28, 1835. S. NORTH. From W. H. Scram, Principal of a Select Classical and English Academy, Troy, New York. MESSRS. KEY & BIDDLE, I have examined the edition of "Goldsmith's England," prepared by Pinnock for the use of schools, and published by you. Also, your editions of " Bridge's Algebra," " Guy's Astronomy," "Keith on the Globes," and the " Scientific Class-Book, Part I." and consider them worthy the attention of teachers of select schools and academies. I shall introduce them into my school as soon as practicable. Yours respectfully, W. H. SCRAM, A.M. Having partially examined the above worK, we feel no hesitation in adding our names to the recommendations already obtained from gentlemen in whose honesty and capability we have the utmost confidence. A. CLARKE, JOS. H. CLARKE. We fully concur in the above recommendation. A. B. CLEVELAND, S. P. SKINNER, A. DINSMORE, C. H. ROBERTSON, JAMES WILKESON, "\ ROBERT WALKER, WM. HAMILTON, / S. CLARK, DAVID RING, JAMES E. SEARLEY, JAMES SHANLEY, { E. RHODES HARNEY, E. YEATES REESE, V ROBT. O'NEILL, N. SPELMAN. J M. POWER, B. WALSH, JNO. PRENTISS, PARDON DAVIS, EDWARD S. EBBS, SAMUEL HUBBELL, MICHAEL TONER. O. W. TREADWELL, Having examined Pinnock's improved edition of Dr. Goldsmith's History of Rome, I unhesitatingly say, that the style and elegance of the language, [14] the arrangement of the chapters, and the questions for examination, render it, in my estimation, a most valuable school book : I therefore most cheer- fully recommend it to teachers, and do confidently trust that it will find an extensive introduction into the schools of our country. Baltimore, September 23, 1835. JA8. F. GOULD. We fully concur in the above recommendation. S. P. SKINNER, A. DINSMORE, C. H. ROBERTSON, JAMES WILKESON, ROBT. WALKER, jos. H. CLARKE, WM. HAMILTON. S. A. CLARKE, DAVID RING, JOSEPH WALKER, JAMES E. SEARLEY, JAMES SHANLEY, SML. ROZEL, E. RHODES HARNEY, E. YEAfES REESE, ROBT. O'NEIL, N. SPELMAN, MICHAEL POWER. B. WALSH, JNO. PRENTISS, PARDON DAVIS EDWARD S. EBBS, SAMUEL HUBBELL, MICHAEL TONER. O. W TREADWELL, From Samuel Jones, A.M., Principal of the Classical and Mathematical Institute, Philadelphia. A writer of so honourable a popularity as Dr. Goldsmith, for all the graces of an elegant, polished, and pure style, and whose histories have been so long and so extensively useful to youth, certainly needs no enco- mium. It may be added, however, for the information of those teachers who are not acquainted with the improvements of Pinnock, that he has been for some time eminent in England for valuable additions to school books. Of the edition of Rome, by Messrs. Key & Biddle of this city, it ia believed that it will be found superior, in the manner of "getting up," to any yet published in this country ; while its attractive appearance and mechanical execution lead me not only to hope, but confidently expect, that they will receive a liberal return for their investment. Philadelphia, September 15, 1835. We fully concur in the above. THOMAS BALDWIN, D. MAGENIS, Teacher of Elocution. WM. A. GARRIGUES, CHARLES HENRY ALDEN, WILLIAM MARRIOTT, THOMAS CONARD, U. KITCHEN, SETH SMITH. J. D. GRISCOM, AUGUSTINE LUDINGTON, CHAS. B. TREGO, THOMAS EUSTACE, J. H. BROWN. JOHN STEEL, T. G. POTTS, JOHN P. ENGLES, WILLIAM MANN, L. W. BURNET, HUGH MORROW, JOHN EUSTACE, SAMUEL JONES. SHEPHERD A. REEVES, JOHN HASLAM, EL. FOUSE, OLIVER A. SHAW, M. L. HURLBERT, RIAL LAKE, BENJAMIN MAYO, WILLIAM M'NAIR, O. K. FROST, SAML. CLENDENIN. THOS. COLLINS, J. O'CONNOR, JNO. STOCKDALE, D. R. ASHTON. BENJAMIN C. TUCKER. JAMES CROWELL, RICHARD M'CUNNEY, JAMES E. SLACK, CHARLES MEAD, E. H. HUBBARD, M. A. CRITTENDEN, Principal of a V. VALUE, ~Young Ladies' Seminary, Phila. EDWARD POOLE. F M. LUBBREN, / ADDITIONAL B.ECOMIVIENDATIONS. From Theodore Strong, LL.D., Professor of Mathematics in Rutgei* College, New Jersey. MESSRS. KEY & BIDDLB, Gentlemen: I am much obliged to you for the copies of the " Scientific Class-Book, Part I." and " Bridges' Algebra." In compliance with your request, that I should give my opinion of their merits, I observed that from a cursory examination I have been led to forma favourable opinion of them. The subjects treated of (in the " Class- Book") appear to be discussed in a very clear and able manner. Besides, there are several important subjects (such as pyronymics, electro-magnetism, &c.) introduced, which are not usually treated of in works of this kind. The Algebra is written in a very perspicuous style, and the subjects investigated appear to be ably handled Yours respectfully, THEODORE STRONG. New Brunswick, July 27, 1835. From C. H. Anthony, Principal of Troy Practical School. I have examined "L'Abeille pour les Enfans," " Bridge's Algebra," and "Scientific Class- Book, Part I.," the books lately published by Messrs. Key & Biddle, and think them superior to most other works on the subjects on which they severally treat. So high an opinion have I of their utility, that I shall endeavour to introduce them into my school as text-books. C. H. ANTHONY. Troy, New York, July 30, 1835. From A. B. Myers, B.A., Principal of Whitehall Academy. MESSRS. KEY & BIDDLB, Gentlemen: I have been much pleased by an examination of "Pinnock's History of England," " Guy's Astronomy." "Keith on the Globes." and the "Scientific Class-Book," together with "Bridge's Algebra." I think them all well entitled to a general introduction into our schools. I cheer- fully give them the preference to any other books of the kind that Lave fallen into my hand Yours, &c. 'A. B. MYERS. Whitehall New York, 1835. From G. W. Francis, A.M., Principal of a Select School, Troy, N. Y. MESSRS. KEY & BIDDLE, Gentlemen: I have formed so favourable an opinion of "Bridge's Alge- bra," "Johnson's Scientific Class-Book," and "Pinnock's Goldsmith's Rome," published by you, that I purpose to introduce them into my school as soon as practicable. Yours, G. W FRANCIS. Troy. July 29. 1835. Geneva College, N. If., 1st Dec. 1835. MESSRS. KEY & BIDDLE, Gentlemen : A few weeks since your agent desired my opinion as to the merits of "Pinnock's Goldsmith's England," "Pinnock's Goldsmith's Rome," "Guy's Astronomy," and the "Scientific Class-book, Part First." I have cursorily examined each, as requested, and have formed the following opinion, viz. : v Pinnock's Goldsmith's England and Pinnock's Goldsmith's Rome ar works of great merit ; are well adapted to ensure the objects intended, and ought to be extensively used in all the schools in the country. Guy's Astronomy contains all that is necessary on that subject for ele- mentary instruction ; more is not desirable in the absence of demonstrative reasoning, which cannot be advantageously employed without previous thorough mathematical preparation. The Scientific Class-book, Part First, is the best work of the kind with which I am acquainted. If the learned author executes the second part with the same judgment and ability as he has the first part, this treatise will deserve, and no doubt receive very extensive patronage. Very respectfully yours, &c., HORACE WEBSTER. [16] .stfromJohn M. Keagy, M.D., Principal of Friends' Academy, Philadelphia. j^ Pinnock's edition of "Goldsmith's Rome" has several very useful addi- jr tions; the one an introduction, containing an abridged view of Roman r- Geography and Antiquities, and the other a very appropriate extension of Roman history to the subjugation of the Empire by the Northern Barbarians. This improved edition of "Goldsmith's Rome" will, no doubt, retain its place in our schools as one of the best abridgments of the history of that interesting people. JNO. M. KEAGY. From J. M'Intyre, English and Classical Teacher, Philadelphia. Pinnock's edition of " Goldsmith's Rome" is, in my opinion, superior to any other : the introductory chapters contain much information new and interesting, and present a favourable specimen of the editor's historical powers. To speak of Goldsmith's style is unnecessary : but of the style of the present editor, we may state, that it is eminently chaste, and little deficient either in purity or precision ; it is dignified, yet not stiff; concise and strong, without roughness or obscurity. Pine Street, October 9, 1835. MESSRS. KEY & BIDDLE, Gentlemen: I have perused, with much interest, the "Scientific Class- Book," edited by Professor Johnson. Allow me to unite my acknowledg- ments, with those of other teachers, for so valuable an aid to the business of instruction. The whole work forms the most clear, exact, and compre- hensive elementary treatise that I have seen on the subjects which it embraces. The value of the work is still farther enhanced as the produc- tion of one long familiar with the topics on which it treats, and thoroughly versed in the mode of presenting them to the mind, in the Various forms of practical instruction. Yours, &c. WILLIAM RUSSELL. Philadelphia, October 6, 1835. From Mr. Myers, A.B., of Vermont. Gentlemen: I think your school-books should be introduced into all our schools as soon as possible. They are just the books which have long been needed, and the sooner they are brought into use the better. Yours, &c. ALLEN B. MYERS. From a communication to the Norwich Courier of October 14th, 1835, by the Rev. John Storrs, Principal of the Norwich Female Academy, the fol- lowing extracts are taken : First The first excellence of this work (" The Scientific Class-Book") is the simplicity of style in which it is composed. Secondly The familiarity of its illustrations is another excellency. Thirdly Connected with this is an abundance and variety of illustration ; so that the subjects presented are brought to the understanding of the most obtuse intellects. Fourthly Another excellency of the work is a due regard to brevity ; which cannot be said of all books treating of the sciences. Fifthly In this book is gathered a large amount of practical knowledge. Hence men in practical life will find in it much valuable information, and many sensible hints. On account of these excellencies I can most cheerfully recommend the work to, your readers. Norwich, Conn., October 13, 1835. JOHN STORRS. MESSRS. KEY & BIDDLE, Gentlemen: "Goldsmith's History of England," as corrected and ar- ranged in your recent edition, is, in my opinion, the best book on its subject which can be put into the hands of young persons. The style of the origi- nal work lias an attractive charm in the ease and fluency of the narrative. [17] It ia a pleasing model of composition, and furnishes excellent matter for the exercises of reading. As a book of history, however, it needed revision and emendation. These it has undergone) to the best advantage, in its present form ; the American editor having used every exertion to render it an acceptable and useful class-book. I am, gentlemen yours, with much respect, Philadelphia, 7th October, 1835. WILLIAM RUSSELL. MESSRS. KEY & BIDDLE, Gentlemen : I have availed myself, with much satisfaction, of the useful volume comprising "Guy's Astronomy" and "Keith's Treatise on the Globes." The former, in its original shape, was one of the best elementary books of its kind ; and the great extent of the latter was the only obstacle to its universal use. The sole form in which it could be used with young learners, was by the transcription of the most important parts of it. To one accustomed to use it in this way, for successive years, your excellent selection was a most valuable and welcome substitute. The volume embracing these two indispensable works forms one of the most compact and economical school-books which the American press has furnished. I am, gentlemen, yours i-espectfully, Philadelphia, 7th October, 1835. WILLIAM RUSSELL. "Guy's Elements of Astronomy" has now been before the public nearly twenty years. During that period, the improvements in this popular trea- tise have kept pace with the great improvements in the science itself, and in the modes of teaching it. It is now, I believe, recognised throughout the United States, and in England, as one among the best class-books in this " y which we have in our language. It is some he most popular treatises on the same subject, r Jand, transcripts from Guy. " Keith on the Globes," as now adapted to our schools, is perhaps unequal- led by any similar work ; and the union of these two in one volume of mode- rate size, was a fortunate arrangement, and has supplied a great desidera- tum to the cause of education, for which the publishers are entitled to much commendation. E. H. BURRITT. New Britain, Conn., Dec. 7, 1835. Professor Johnson has rendered the public an invaluable service in "Scientific Class-book." It is a treasure of useful knowledge, happily adaptt not only to the wants of the student, but not less so to the general rea< There is so much intrinsic merit in this volume, so much of what e\ youth of every grade in the country should, in some sense, be familiar i that I am sure it needs only to be known to ensure it a wide circulat Aside from its peculiar merit as a class-book for the higher schools, I \ say to every young man in the United States, about to engage in the bus of life. Let the Scientific Cl-ass-book be your constant companion. New Britain, Conn., Dec. 7, 1835. E. H. BUI I have long been acquainted with Mr. Bridge's larger system of and am gratified that an author so competent to the task has furry elementary treatise for junior pupils. This rs so simple, clear, arranged, as to place the acquisition of this very essential branch matics within the reach even of common schools. The importan' a work, of great perspicuity in the rules and examples ; of explaU and familiarly the dependence and connexion between each sue/ and thus conducting the learner, by easy gradations, from the pies of a simple equation to the investigation of the higher am to have been fully understood and dnly appreciated by the, valuable elementa'ry treatise on Algebra. E ; H^BU^ New Britain, Conn., Dec. 7, 1835. branch of Natural Philosophy which we have in our language. It is some evidence of this, that one of the most popular treatises on the same subject, since published in England, and two others in this country, are chiefly but [18] From Rev. W. C. Fowler, A.M., C. A. S.f Professor Middkbury College, Vermont. The "Scientific Class-book" is admirably adapted to the use of high schools and academies, as an introduction to the principles of physical science. It is neither a meagre sketch on the one hand, nor on the other is it overloaded with facts. The principles are distinctly announced, and the illustrations and proofs are interesting and satisfactory. "Goldsmith's Rome" and "Goldsmith's England," coming from one who "adorned every thing that he touched," needed only what has been done by Pinnock to make them as well suited to the purposes of class-books in academies, as they were before to general reading. "Guy's Astronomy" and "Keith on the Globes," two in one, are excel- lent for unfolding a science in which, from the grandeur of the objects pre- sented, every youth and every man must feel a strong curiosity and a deep interest. WILLIAM C. FOWLER, Professor of Chemistry. From Rev. David R. Austin, A.M. Principal of Monson Academy, Monson, Mass. " Bridge's Algebra" has been adopted as a text-book in Monson Academy, and I can state, with the utmost confidence, that it is superior to any work of the kind within my knowledge. The arrangement is methodical, the statement of principles clear and concise. The pupils are uniformly pleased with it, and their progress greatly facilitated. D. R. AUSTIN. Jan. 19, 1836. The "Scientific Class-book" has been introduced into Monson Academy, and I do not hesitate to say that this book far exceeds any elementary trea- tise upon similar subjects which 1 have seen. This work deserves the patronage of the public ; and 1 can cordially recommend it as a suitable book to introduce into common schools and academies throughout the land. Jan. 19, 1836. D. R. AUSTIN. From the. Misses Barnard. We have looked through your little volume of " Sacred History," and are very much pleased with it. We have long felt the deficiency of our pupils in this branch of education, and are happy to introduce to their notice a work so well worthy their attention as is yours, in the humble opinion of MISSES BARNARD. Philadelphia, Aug. 1st, 1835. MESSRS. KEY