Arago, Biot, and a few others, have reduced the apparently intricate and variable phenomena of double refraction and polarisation under the dominion of general laws,' and have enabled us to calculate them, in the language of Dr Brewster, with as much accuracy as that, with which the astronomer can compute the motions and positions of the heavenly bodies.' It must be gratifying to mineralogists to learn that the results of the investigations of Dr Brewster are about to be applied to the classification of minerals, and that that gentleman is preparing a work, founded chiefly on the physical relations of minerals, and on the characters derived from optical phenomena, and the action of crystals on polarised light. The third and fourth chapters are devoted to the sources and properties of the simple supporters of combustion, and of the elementary acidifiable substances, and their mutual combinations.' In the section on carbon, the magnificent diamond mentioned by Tavernier is noticed as probably the largest known. It is of the size of a hen's egg, and weighs 279 carats ;-before cutting, it weighed 900 carats. This, however, is far exceeded by a diamond not noticed by Mr Brande, of which the following account, from the third edition of professor Jameson's mineralogy, may not be uninteresting. This diamond is said to be in the possession of the rajah of Mattan, in Borneo, in which island it was found about eighty years ago. It is egg-shaped, with an indented hollow near the smaller end. It is said to be of the finest water. It weighs 367 carats. Now, as 156 carats are equal to one ounce Troy, it is obvious that this diamond weighs two ounces 169.87 grs. Troy. Many years ago the governor of Borneo attempted to purchase this diamond. He sent a Mr Stewart to the rajah, who offered 150,000 dollars, two large war-brigs, with their guns and ammunition, together with a certain number of great guns, and a quantity of powder and shot. The rajah, however, refused to deprive his family of so valuable a hereditary possession, to which the Malays attach the miraculous power of curing all kinds of diseases, by means of the water in which it is dipped, and with which they imagine that the fortune of the family is connected.' In the section to which we have just alluded, Mr Brande has given a brief sketch of the operations connected with the application of coal gas to the purposes of illumination. As this mode of lighting streets and buildings has been attempted in various places in this country without success, arising in a great measure from the high price of coal, we beg leave to call the attention of the enterprising and speculative to the apparatus for the conversion of oil into gas. It appears that the commonest and most impure kinds of whale or other oils, which are quite unfit for burning in the usual way, afford an abundance of excellent gas, requiring no other purification than passing through a refrigerator, to free it of a quantity of empyreumatic vapor. A gallon of whale oil affords about 100 cubical feet of gas, and an Argand burner, equal to seven candles, consumes a cubical foot and a half per hour.' The cost of a lamp fed by oil gas, and giving the light of seven candles, is stated at three farthings per hour of Argand's lamp, with spermaceti oil, mould candles, 3d. 31d. 14d.' Mr Brande has ascertained, by a series of experiments, conducted with every requisite caution, that, to produce the light of ten wax candles for one hour, there were required 2600 cubical inches of carburetted hydrogen or olefiant gas, 4875 13120 oil gas, coal gas. The fitness of the gas obtained from coal is dependent on the quantity of carburetted hydrogen, or olefiant gas, contained in it, and the fitness of the purified mixed gas for illumination, will be directly as its specific gravity.' It has been proved by experiment, that' purified coal gas seldom contains more than 40 per cent. in volume of carburetted hydrogen, while oil gas generally affords about 70 per cent.; hence its superiority for burning and the relatively small quantity consumed.' The gas is obtained by decomposing the oil, and for this purpose a very simple apparatus is required, consisting of a furnace with a contorted iron tube, containing fragments of brick or coke,' and the oil is suffered to drop into this. The oil is converted almost entirely into charcoal, which is deposited in the tube, and into a mixture of carburetted hydrogen, and hydrogen gases, of which from two to three cubic feet may be regarded as equivalent to five or six of coal gas, for the production of light.' The fifth chapter of the work before us embraces the metals and their compounds. In the section on nickel we find rather a meagre account of aërolites or meteoric stones. The ter restrial formation of these bodies, Mr Brande considers as disproved by the most satisfactory and indisputable evidence. The opinion to which he inclines, in regard to their origin, will be evident from the following quotation. To account for these uncommon visitations of metallic and lapideous bodies, a variety of hypotheses has been suggested. Are they merely earthy matter, fused by lightning? Are they the offspring of any terrestrial volcano? These were once favorite notions; but we know of no instance in which similar bodies have in that way been produced, nor do the lavas of known volcanoes in the least resemble these bodies; to say nothing of the inexplicable projectile force that would here be wanted. This is merely explaining what is puzzling, by assuming what is impossible; and the persons who have taken up this conjecture, have assumed one impossibility to account for what they conceive to be another, namely, that the stony bodies should come from any other source than our own globe. The notion that these bodies come from the moon is, when considered, neither absurd nor impossible. It is quite true, that the quiet way in which they visit us is against such an origin; it seems, however, that any power which would move a body 6000 feet in a second, that is, about three times the velocity of a cannon ball, would throw it from the sphere of the moon's attraction into that of our earth. The cause of this projective force may be a volcano, and if thus impelled, the body would reach us in about two days, and enter our atmosphere with a velocity of about 25000 feet in a second. Their ignition may be accounted for, either by supposing the heat generated by their motion in our atmosphere sufficient to ignite them, or by considering them as combustibles, ignited by the mere contact of air. While we are considering the possibility of these opinions, it may be remembered, that in the great laboratory of the atmosphere, chemical changes may happen, attended by the production of iron and other metals; that, at all events, such a circumstance is within the range of possible occurrences; and that the meteoric bodies which thus salute the earth with stony showers, may be children of the air, created by the union of simpler forms of matter. The singular relationship between iron and nickel and magnetism, and the uniform influence of meteoric phenomena on the magnetic needle, should be taken into account in these hypotheses.' Neither professor Brande nor the American editor, has taken any notice of the theory proposed by president Clap, of Yale college. He supposed that meteors are small terres 6 trial comets revolving about the earth in the same manner as the solar comets revolve about the sun. That moving in very eccentric orbits, when in perigee, they pass through the atmosphere, are highly electrified, and consequently become luminous. As they approach their lower apside, their electricity is discharged, the body disappears, and a report is heard. This being admitted, it is not strange that, by the violence of the shock, portions of the meteor should be thrown to the earth, while the main body, not sensibly affected by so small a loss, continues to move on in its orbit, and of course ceases to be luminous.' (Amer. Philos. Trans. Vol. 6.) We are aware of the objections to this hypothesis, and that it has been ably discussed by Dr Blagden. But when we consider that it was started before the modern discovery of the four small planets, before the discovery of a comet with a period of only twelve hundred days, of which we gave an account in our last number, and before the discovery of a revolving transparent nebulous substance made by Dr Olbers, and mentioned in this journal for April 1820, we think president Clap's conjecture does him great credit, and that it required far greater reach of speculation than it would now do. In the sixth chapter of the work under review, there are many valuable details respecting the analysis of metalliferous compounds, in which the author, as he candidly acknowledges, has availed himself largely of the invaluable analytical labours of Klaproth and others. The correctness of these processes appears to have been, for the most part, submitted to the test of experimental repetition in the laboratory of the Royal Institution.' We find many judicious remarks in regard to the difficulties and fallacies by which the young analyst is too apt to be discouraged, and fully agree with our author, that the practice of submitting substances of known composition to analysis, cannot be too strongly recommended to the chemical student. It makes him acquainted with the mutual actions and habitudes of a number of bodies which experience can alone teach, and gives a dexterity of manipulation and an accuracy in conducting experimental inquiries, of which he will find the value when subsequently in the pursuit of original investigations.' We were not a little surprised to see the blow-pipe of the old form, the application of which is exceedingly difficult to be acquired, recommended for general use. No notice is taken of the improved instrument of Mr Brooke, which, though not quite so portable as the former, is on every other account to be preferred; nor is there any description of the more powerful apparatus of our ingenious countryman, professor Hare. These omissions of Mr Brande should by all means have been supplied by the American editor. The seventh chapter on the analysis of mineral waters, is preceded by a plan and description of a portable laboratory, which will be found highly convenient for all the necessary operations in these interesting and important researches. Mr Brande has not adverted to the mode of analysis recommended by the late Dr Murray, because', as he observes, 'I cannot admit the existence of incompatible salts to the extent which his principle requires.' The student is referred for a variety of useful details to the works of Drs Marcet and Scudamore; Messrs Phillips and Thenard. 6 The objects of the eighth chapter are the formation of vegetable substances and their chemical physiology, the analysis of vegetable products and the properties of their proximate component parts, and the phenomena and products of fermentation. The ninth chapter is devoted to the subject of animal chemistry. The remainder of the volume is principally geological, and is in fact a reprint of the author's Outlines of Geology,' published in 1817. An account of the principal chemical characters of minerals is an important part of every treatise on chemistry, but we are disposed to consider the introduction of geological speculations as superfluous. As these sections, however, have been retained by the American editor, we should have been pleased to have seen those additions and ' emendations,' which they so evidently require. We have not found a reference to a single locality of American minerals, nor to any of those points in the geological structure of this country, which might, with very little labor, have been added. Such additions would have rendered this part of the work far more interesting and valuable. Professor Brande evidently inclines to the Huttonian hypothesis, in regard to the origin of rocks, but has given an interesting and perspicuous abstract of the opinions of other geologists most entitled to attention. The following is his description of a set of rocks, which from personal examination, we know bear a great resemblance in structure to some in the vicinity of this |