Busceptibility) heat be communicated, its temperature may it follows, that the temperature must fall: hence arise the Freezing mixeffects of freezing mixtures. tures. this. It scarcely need be added, that the converse of all this Corverse of will take place, if the susceptibility for vibration be increased, and no abstraction of heat be made. The temperature then must rise; for the body contains within itself what may be termed the power of vibration; a given quantity of which produces a greater intensity of vibration in any body, according to the susceptibility of that body for vibration. Such is an imperfect sketch of the hypothesis of vibration, which I proposed to give. Many circumstances, which would have elucidated, and perhaps have confirmed the opinions, have been necessarily onitted; and here the greatest candour of your readers will be constantly required. It may be useful in concluding, to present a summary of Summary. the circumstances which have been considered; and thus to institute a comparison between the two hypotheses. 1st, The firft principles of each opinion are equally hy- The two hypopothetical. 2dly, The production of heat by friction is explained by the hypothesis we propose; but not, satisfactorily at least, by the other. 3dly, Certain facts have been related, under the head of the effects of heat, which appear to afford fome degree of. contradiction to the hypothesis of material caloric; and although they may not be easily explained on the opposite principle, yet they do not by any means appear contradictory to it. The advantages of our theory appear most conspicuous in the following particulars; for 4thly, The properties of good conductors, and of good radiators of caloric, are explained by it alone. theses com pared. 5thly, The same observation applies to the difference of solar and culinary heat; 6thly, And in particular to the radiation of cold. 7thly, The opinion of capacity for caloric is hypothetical; that of the difference in susceptibility for vibration is in conformity to the usual order of nature, in dispensing the other properties of matter. On a Combination of Oximuriatic Gas and Oxigen Gas. By I SHALL beg permission to lay before the Society the acCompound of oxigen and ox count of some experiments on a compound of oximuriatic imuriatic gas. gas and oxigen gas, which, I trust, will be found to illastrate an interesting branch of chemical inquiry, and which offer some extraordinary and novel results, I was led to make these experiments in consequence of the difference between the properties of oximuriatic gas prepared in different modes; it would occupy a great length of time, to state the whole progress of this investigation. It will, I conceive, be more interesting, that I should immediately refer to the facts; most of which have been witnessed by Members of this Body, belonging to the Committee of Chemistry of the Royal Institution. The oximuriatic gas prepared from manganese, either by mixing it with a muriate and acting upon it by sulphuric acid, or by mixing it with muriatic acid, is, when the oxide of manganese is pure, and whether collected over water or mercury, uniform in its properties; its colour is a pale yellowish green; water takes up about twice its volume, and scarcely gains any colour; the metals burn in it readily; it * Phil. Trans, for 1811, p. 155. combines combines with hidrogen without any deposition of moisture: it does not act on nitrous gas, or muriatic acid, or carbonic oxide, or sulphureous gasses, when they have been carefully dried. It is the substance which I employed in all the experiments on the combinations of oximuriatic gas described in my last two papers. The gas produced by the action of muriatic acid on the Varies when procured from salts which have been called hyperoximuriates, on the con- hyperoximutrary, differs very much in its properties, according as the riates. manner in which it is prepared and collected is different. When much acid is employed to a small quantity of salt, and the gas is collected over water, the water becomes tinged of a lemon colour; but the gas collected is the same as that procured from manganese.. When the gas is collected over mercury, and is procured from a weak acid, and from a great excess of salt, by a low heat, its colour is a dense tint of brilliant yellow green, and it possesses properties entirely different from the gas col-: lected over water. It sometimes explodes during the time of its transfer. from one vessel to another, producing heat and light, with an expansion of volume; and it may be always made to explode by a very gentle heat, often by that of the hand*. It is a compound of oximuriatic gas and oxigen, mixed A compound. with some oximuriatic gas. This is proved by the results of its spontaneous explosion. It gives off, in this process, from to its volume of oxigen, loses its vivid colour, and becomes common oximuriatic gas. I attempted to obtain the explosive gas in a pure form, Attempts to obtain it pure, by applying heat to a solution of it in water; but in this case, there was a partial decomposition; and some oxigen * My brother, Mr. J. Davy, from whom I receive constant and able assistance in all my chemical inquiries, had several times observed explosions, in transferring the gas from hyperoximuriate of potash, over mercury, and he was inclined to attribute the phænomenon to the combustion of a thin film of mercury, in contact with a globule of gas. I several times endeavoured to produce the effect, but without success, till an acid was employed for the preparation of the gas, so diluted as not to afford it without the assistance of heat. The change of colour and expansion of volume, when the effect took place, immediately convinced me, that it was owing to a decomposition of the gas. was was disengaged, and some oximuriatic gas formed. Finding that, in the cases when it was most pure, it scarcely acted upon mercury, I attempted to separate the oximuririatic gas with which it is mixed, by agitation in a tube with this metal; corosive sublimate forined, and an elastic fluid was obtained, which was almost entirely absorbed by of its volume of water. Dangerous. This gas in its pure form is so easily decomposable, that it is dangerous to operate upon considerable quantities. Analysis of it. In one set of experiments upon it, a jar of strong glass, containing 40 cubical inches, exploded in my hands with a loud report, producing light; the vessel was broken, and fragments of it were thrown to a considerable distance. I analysed a portion of this gas, by causing it to explode over mercury in a curved glass tube, by the heat of a spirit lamp. The oximuriatic gas formed, was absorbed by water; the oxigen was found to be pure, by the test of nitrous gas. 50 parts of the detonating gas, by decomposition, expanded so as to become 60 parts, The oxigen, remaining after the absorption of the oximuriatic gas, was about 20 parts. Several other experiments were made, with similar results. So that it may be inferred, that it consists of 2 in volume of oximuriatic gas, and I in volume of oxigen; and the oxigen in the gas is condensed to half its volume. Circumstances conformable to the laws of combination of gaseous fluids, so ably illustrated by Mr. Gay-Lussac, and to the theory of definite proportions. I have stated on a former occasion, that approximations to the numbers representing the proportions in which oxigen and oximuriatic gas combine are found in 7-5 and 32·9. And this compound gas contains nearly these quantities*. The * In page 245 of the Phil. Trans, for 1810, (Journal, vol. XXVII, p. $33,) I have mentioned, that the specific gravity of oximuriatic gas is between 74 and 75 grains per 100 cubical inches. The gas, that I weighed, was collected over water, and procured from hyperoximuriate of potash, and at that time I conceived, that this elastic fluid did not differ from the oximuriatic gas from mangenese, except in being purer. It Spec grav, of probably contained some of the new gas; for I find, that the specific gra gas. The smell of the pure explosive gas somewhat resembles Smell of the that of burnt sugar, mixed with the peculiar smell of oximuriatic gas. Water appeared to take up eight or ten Solubility. times its volume; but the experiment was made over mercury, which might occasion an errour, though it did not seem to act on the fluid. The water became of a tint ap proaching to orange. oximuriatic gas for hidro When the explosive gas was detonated with hidrogen Attraction of equal to twice its volume, there was a great absorption, to more than, and solution of muriatic acid was formed; gen. when the explosive gas was in excess, oxigen was always expelled, a fact demonstrating the stronger attraction of hidrogen for oximuriatic gas than for oxigen. compound on metals, I have said that mercury has no action upon this gas in Action of the its purest form at common temperatures. Copper and antimony, which so readily burn in oximuriatic gas, did not act upon the explosive gas in the cold: and when they were introduced into it, being heated, it was instantly decomposed, and its oxigen set free; and the metals burnt in the oximuriatic gas. When sulphur was introduced into it, there was at first sulphur, no action, but an explosion soon took place: and the pecu liar smell of oximuriate of sulphur was perceived. Phosphorus produced a brilliant explosion, by contact phosphorus, with it in the cold, and there were produced phosphoric acid and solid oximuriate of phosphorus, Arsenic introduced into it did not inflame; the gas was arsenic, made to explode, when the metal burnt with great brilli ancy in the oximuriatic gas. Iron wire introduced into it did not burn, till it was iron, heated so as to produce an explosion, when it burnt with a most brilliant light in the decomposed gas. Charcoal introduced into it ignited, produced a brilliant charcoal, flash of light, and burnt with a dull red light, doubtless vity of pure oximuriatic gas from manganese and muriatic acid is to that oximuriatic of common air, as 244 to 100. Taking this estimation, the specific gra- gas, viry of the new gas will be about 238, and the number representing the proportion in which oximuriatic gas combines, from this estimation, will be rather higher than is stated above. |