VII.

Farther Observations and Experiments on Oximuriatic Acid, by J. MURRAY, Lecturer on Chemistry, Edinburgh.

SIR,

To Mr. NICHOLSON.

IN a former communication I had given an account of

oximuriatic

some experiments, which I regarded as subversive of Mr. Davy's lately proposed hypothesis on the nature of muriatic and oximuriatic acids. Of these some of the results were Result of the called in question by that gentleman, particularly that in action of carbonic oxide, which carbonic oxide, hidrogen, and qximuriatic acid gasses hidrogen, and were subjected to mutual action, either at a low tempera- acid, questionture or by detonation. The production of carbonic acid in ed. this experiment he appeared to have considered as arising from the operation of the water introduced with the view of examining the product; he employed therefore dry ammoniacal gas, and with this variation he stated, that there is no conversion of carbonic oxide into carbonic acid. Though satisfied, that there is little probability in the supposition of any fallacy from this source, I thought it right to repeat the experiment so as to exclude its operation, and having lately done so, I beg leave to communicate the result.

I may previously remark, that I had objected to the im- Mr Davy's experfect manner in which Mr. Davy's experiment was exe- periments on the subject cuted; no attempt apparently having been made to discover if carbonic acid were formed, but its nonformation having been inferred merely from the residual gas burning with the same coloured flame as carbonic oxide. This has since been attended to, and the experiment performed with a more strict examination of the result. An account is given by Mr. J. Davy in his last communication of this repetition of the experiment. A mixture of 10 measures of carbonic oxide, 4 measures of hidrogen, and 14-6 measures of oximuriatic acid gas contaminated with 2 of common air, was inflamed by the electric spark; the residual air being detonated with oxigen was found to contain 8 measures only of carbonic oxide; 2 measures of this gas therefore had disappeared,

produced car. bonic acid,

for.

appeared, and it appears to be admitted in the statement of the experiment had been converted into carbonic acid, as indeed no other conclusion could be drawn. But this is ascribed to the action of the common air, or of moisture in the gasses; and it is inferred, that, when the action of these is taken into account, "no result more satisfactorily cou"clusive that no carbonic acid was formed could be ex"pected."

It is at least established, that in this experiment, when the results are submitted to accurate examination (even with the precaution, which Mr. Davy deems so essential, of substituting ammonia for water), there is a conversion of carbonic oxide into carbonic acid. The fact therefore is admitted, which I had asserted, and which had been before not satisfacto- denied. The suppositions by which it is now attempted to rily accounted be accounted for I regard as unsatisfactory, no proof being given, either that the causes assumed did operate, or were adequate to the production of the effect. With regard to the supposed operation of the atmospheric air mingled with the oximuriatic gas, it is not probable, that, diluted as it must be by the large intermixture of elastic fluid, its oxi gen would combine with the carbonic oxide in the feeble inflammation, which from the small portion of hidrogen employed would take place in the experiment. And even if it had combined, the quantity of it was not sufficient to have converted into carbonic acid half the quantity of carbonic oxide which disappeared. With regard to the supposed effect from moisture, as the carbonic oxide and hidrogen gasses were previously dried, it can scarcely be assumed to have been present to the extent which it is necessary to suppose, allowing even that it could operate in the momentary action from the detonation. And if there were grounds for supposing, that these circumstances were of any importance in producing the result, why were they allowed to operate? It is easy to obtain oximuriatic gas without such an intermixture of common air as 2 measures in 14; it can also be dried by submitting it to the action of substances which abstract water. When they could thus have been excluded, the only reason that could justify this admission was the belief, that their influence was so unim

portant

portant that it might be disregarded. But to admit them, and at the same time to assume that their operation had given rise to the result, the possibility of obtaining which independent of such circumstances is the very question at issue, appears to be making by choice an ambiguous instead of a decisive experiment. I am satisfied however, that these circumstances had no important effect. And when we have the actual formation of carbonic acid, and only such modes of accounting for it to avoid the conclusion, that oxigen is communicated from oximuriatic acid, I cannot but regard the result as being in conformity with that which I have always stated to be obtained.

them too small.

One other observation with regard to this experiment I The proportion find it necessary to make. In employing hidrogen gas to of hidrogen in promote the action of oximuriatic acid on carbonic oxide, the proportion I used was equal volumes of the hidrogen. and carbonic oxide, and in the repetition of the experiment with the view of ascertaining if the result I had stated were accurate it was to be expected, that the same proportion would have been observed. Mr. Davy in his former experiment used the proportion of 8 parts of hidrogen to 10 of carbonic oxide, a deviation of no great importance, and of which therefore I did not think it necessary to take notice. But he has now employed the proportion of only 4 measures of hidrogen to 10 of carbonic oxide. I know not what may have been the reason for this change of proportion, but it is obvious what effect is to be expected from it. I had found, that dry carbonic oxide gas, and oximuriatic acid gas, do not act on each other; and I had affirmed, that they do act, and that there is a production of carbonic acid, when a portion of hidrogen is added. According to the view with which that hidrogen was added, that of affording a certain portion of water necessary to the constitution of muriatic acid gas, the larger the quantity used, the conversion of carbonic oxide into carbonic acid by the oximuriatic acid might be expected to be more complete. Mr. Davy repeats the experiment with the view of disproving the result I had affirmed to be obtained; but he reduces the proportion of hidrogen more than one half; and from not atfending to the effect of it, he withdraws as far as possible

the

Farther expe

stituting ammonia for wa

the very circumstance held to be essential to its success. And still with this variation part of the carbonic oxide is converted into carbonic acid.

I have now to state the results of the experiments I have riments sub- performed, substituting ammonia for water, in examining the product of the mutual action of the gasses. I was assisted as before in making these experiments by my friend Mr. Ellis, and the results were witnessed by some other friends.

ter.

Exp. 1.

Carbonic acid apparently produced,

Presence of

Ten measures of carbonic oxide gas, and 10 measures of hidrogen gas, each of which had been previously dried by exposure to lime, and 20 measures of oximuriatic acid gas, obtained from a mixture of muriate of soda, black oxide of manganese, and diluted sulphuric acid, and which had been kept in contact with muriate of lime, were mixed together in an apparatus fitted with stopcocks, so that the gasses could be transferred and mingled without the intervention of water or of quicksilver. The mixture was exposed to light, excluding the direct action of the solar rays, for about 36 hours. At the end of that time, the apparatus being opened under dry quicksilver, a small quantity only entered, indicating a very inconsiderable diminution of volume; and the quicksilver acquired a slight tarnish, a proof of the presence of a small portion of oximuriatic acid. The gas was transferred through dry quicksilver into an inverted jar; and ammoniacal gas, which had been previously dried by exposure to lime, was added to it. Dense white vapours were abundantly produced, and the introduction of the ammonia was renewed from time to time, until their production had ceased. A little water was then introduced to absorb the excess of ammonia, and dissolve the concrete salt that had condensed. The solution was rendered turbid by the test of muriate of barytes, indicating the production of carbonic acid *.

I soon

In some experiments this result was not obtained, or the transpacarbonic acid rency of the solution was at least little impaired. To discover the cause not always imof this I had dissolved small portions of muriate and carbonate of ammomediately per ceptible. nia in water, thus preparing a solution similar to that which I supposed to be formed in the experiment; but on adding to it muriate of barytes there

f

cal.

carbonic acid

I soon ascertained this in a manner altogether unequivo- Formation of The concrete salt, condensed on the sides of the jar proved. when the action of the ammonia had ceased, being collected, e on dropping it into dilute muriatic acid, a sensible effervescence was observed, especially when it had been taken from the upper part of the inverted jar. This latter circumstance appeared to indicate, that the ammonical gas, when introduced to the elastic fluid remaining after the mutual action of the three gasses, had combined first with the muriatic acid, and afterward more slowly with the carbonic acid that had been formed, so that the product of this latter combination had been deposited principally towards the head of the jar; a result which might indeed be expected from the more powerful action of muriatic acid, than of carbonic acid, on ammonia. This afforded a mode of obtaining the two products in a great measure separate. On adding the first portion Exp. 2 of ammonia, the white vapours were allowed to condense, the residual gas was transferred into another jar, and a fresh portion of ammonia added. The salt obtained from the sides of the first jar was principally muriate of ammonia, that from the second was carbonate, and when dropped on a dilute acid effervesced as strongly as pure carbonate of ammonia did. The production of carbonic acid was established therefore beyond the possibility of doubt: it farther appears, that the conclusion I had drawn from my former experiments was correct, and that there is no fallacy in the introduction of water after the mutual action of the gasses to examine the product, the result being equally decisive when ammonia is employed.

The residual gas in these experiments was found to be a Residual gas, mixture of hydrogen and carbonic oxide, with a little ni

there was no precipitation; and I farther found, that the transparency of a solution of pure carbonate of ammonia is not immediately impaired by this test. This may be ascribed partly perhaps to the action of ammonia counteracting the formation of carbonate of barytes, hut principally to the excess of carbonic acid in the carbonate of ammonia, which contributes to retain the barytes dissolved. Hence subcarbonate of ammonia gives a precipitate with muriate of barytes, and in the above experiment the solution became turbid on the addition of the muriate only when an excess of ammonia had been added to the elastic fluid formed by the mutual action of the gasses.

trogen