water.

tion, the phenomena of light, heat, and of the boiling point of Our efforts will be particularly directed to effect the ascent of the highest point of Monta Rosa; and we venture to say, that we want neither the courage nor the bodily strength which this ascent requires.

ART. XLVI.--Experiments on the Application of Professor Dæbereiner's recent Discovery, to Eudiometry. By EDWARD TURNER, M. D., Fellow of the Royal College of Physicians, and Lecturer on Chemistry, Edinburgh. [Ed. Philos. Journ.] (Concluded from p. 243.)

It appeared, from some experiments related in a preceding part of this paper, that the presence of certain gases has a positive influence in diminishing, or even preventing the action of platinum. A nearer investigation of this point was of course connected with the immediate object of the present inquiry, but was undertaken, not with this intention alone, but with the view of drawing a parallel between Platinum and Electricity, relative to their action on explosive

mixtures.

Given volumes of a mixture composed of hydrogen and oxygen, in the exact proportion to form water, and quite dry, were mixed with various quantities of other gases, and submitted to the action of electricity. A strong charge from a Leyden jar did not cause detonation, when one volume of the explosive mixture was diluted with

By reference to p. 77, of Sir H. Davy's work on the safetylamp, it will be seen, that several of my results differ slightly from his. The chief difference relates to the action of Nitrous Oxide, which he finds to have a considerably less influence than oxygen in preventing detonation; while my observation leads to an opposite conclusion. The nitrous oxide I employed was collected over mercury, was well dried, and was not used for hours after its formation.

Sir H. Davy has satisfactorily proved, that the combustion of an explosive mixture ceases when the heat produced in the process is very rapidly removed; and he has rendered it probable, that the coexistence of carbonic acid and other gases tends to extinguish burning bodies, by the velocity with which they carry off the caloric disengaged during the combustion. It is, however, by no means clear, that this is the only efficient principle, and an investigation of the relative power of different gases in preventing the inflammation of combustible substances, would be very interesting, and might throw considerable light upon this subject. From the close analogy between the effects of Flame and of Electricity, on explosive gaseous mixtures, it must be supposed that the same causes which modify the action of the one, would likewise exert some influence on the other. Now, reasoning from the best data we at present possess, it is impossible to maintain, that the effect of different gases in preventing the action of electricity arises only from their cooling agencies. Hydrogen and nitrous oxide, whose capacities for heat, according to De Laroche and Bérard, are widely different, have an equal power of counteracting the effect of electricity. The capacities of olefiant gas and nitrous oxide bear no proportion to their relative powers of preventing explosion; and, by reference to the preceding Table, other examples of a similar nature will readily present themselves. It is therefore probable, that some other than the usually acknowledged principle is applicable in the instance of combustion, as well as in that of electricity. This view receives additional support from the following experiments.

The presence of oxygen, bydrogen, and atmospheric air, has so little power in preventing the action of platinum, that I have not been able to ascertain the exact limits at which it ceases in such mixtures.

Very different is the effect of some other elastic fluids. In mixtures composed of

The explosive mixture was, as usual, formed of 2 volumes of hydrogen to 1 of oxygen. By the term, warm, is meant, that the ball was put into the gas when just so hot as to be borne on the palm of the hand. The most active ball which I could make was employed in these experiments; when a weaker was used, but one which nevertheless acted with energy on the pure explosive mixture, the counteracting effect of several gases, as carbonic oxide, olefiant and ammoniacal gas, was far greater than is stated in the preceding Table.

This singular property of certain gases can by no means be attributed to their cooling agency, for platinum acts on an explosive mixture of oxygen and hydrogen, even when quite cold; nor will the mere circumstance of dilution account for the phenomena. Heat is always generated by the chemical changes produced; and this heat, in ordinary circumstances, greatly augments the energy of the platinum; but mere abstraction of caloric could obviously have no other effect than to cause a slower action. We must therefore admit the operation of some other cause, which is at present quite undetermined; and, as the same gases which prevent the action of platinum, likewise control the influence of electricity, it seems rational to infer, that the same power operates to a certain extent in both cases.

I have hitherto made no allusion to the principle by which platinum acts in causing the combination of oxygen and hydrogen gases. The investigation is so obscure and difficult, that it can only be attempted with a prospect of success after the accumulation of many facts; nor do the experiments I have hitherto make, justify the decided adoption of any opinion. Prof. Dabereiner imagines that galvanism is the principle concerned; that, by putting platinum into an explosive mixture, we establish a simple galvanic circle, in which the hydrogen represents the zinc. That ingenious chemist

has not, to my knowledge, advanced one argument in proof of his assumption, and has been led to it purely, as I imagine, by the impossibility of explaining the phenomena on any other known principle. It is, however, better in science to account for phenomena on known principles, than to search unnecessarily for new; and, as galvanism does afiord us a rational explanation, while we have no positive proof that it is not the agent concerned, we can hardly refuse a certain degree of belief to the ingenious supposition of Prof. Dœbereiner. The facts which have been stated in the present paper give additional plausibility to this view; for, on taking a comparative survey of the two Tables, which show the effect of gases in preventing the action of electricity and platinum, a singular coincidence will be observed, which certainly cannot be the result of chance. One or two exceptions do indeed occur, but these are far outweighed by the instances which are favourable to this side of the question, and which may be adduced in support of it. It must, on the contrary, be confessed, that all my attempts to render electrical excitement evident, by means of an electrometer, have wholly failed. This negative argument does not, however, merit much confidence, because the copious production of water forms such a conducting atmosphere around the metal, as effectually to prevent the most delicate electrometer from being affected.

Before concluding this paper, I shall mention a few detached facts, which may not be uninteresting to the Society, and which will show what precautions are necessary for ensuring the regular action of platinum.

On exposing pure spongy platinum to the air and dust of an ordinary sitting-room, the metal gradually loses its peculiar property. After three days it still became luminous from a jet of hydrogen, but at the end of six days no action ensued, not even when it was put into a mixture of oxygen and hydrogen. By simply igniting the platinum, its energy was completely restored. A piece of platinum was kept in a closed drawer of the same apartment in such a manner, that it was freely exposed to the air, but protected from dust. At the close of a fortnight, it still set fire to hydrogen, though its energy was somewhat diminished. Some of the metal was kept a month in a dry bottle, furnished with a glass-stopper, and then acted quite well. A platinum bail lost and retained its energy under similar circumstances.