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ARTICLE V.

Erperiments on Muriatic Acid Gas, with Observations on its

Chemical Constitution, and on some other Subjects of Chemical
Theory. By John Murray, M.D. F.R.S.E. Fellow of the
Royal College of Physicians of Edinburgh.*

Some years ago I proposed, as decisive of the question which has been the subject of controversy on the nature of oxymuriatic and muriatic acids, the experiment of procuring water fro

from muriate of ammonia, formed by the combination of dry ammoniacal and muriatic acid gases. Muriatic acid gas being the sole product of the mutual action of oxymuriatic gas and hydrogen, it follows, that if oxymuriatic gas contain oxygen, muriatic acid gas must contain combined water; while, if the former be a simple body, the latter must be the real acid, free from water. When muriatic acid gas is submitted to the action of substances which combine with acids, water is obtained; but though the most simple and direct conclusion from this is, that the water is deposited from the muriatic acid gas, the result may be accounted for on the opposite doctrine, by the supposition that it is water formed by the combination of the hydrogen of the acid with the oxygen of the base. Ammonia, however, containing no oxygen, if water is obtained from its combination with muriatic acid

gas, we obtain a result which cannot be accounted for on this hypothesis, but must be regarded as a proof of the presence of water in the acid gas. And this again affords a proof equally conclusive of the existence of oxygen in oxymuriatic gas.

The results of the experiment which I had brought forward were involved in much controversial discussion : and brief recapitulation of the objections that were urged to it is necesa sary, as an introduction to the experiments I have now to submit ; and to the consideration of the present state of the question.

The original experiment was performed by combining thirty cubic inches of muriatic acid gas with the same volume of ammoniacal gas carefully dried. The salt formed was exposed in a small retort with a receiver adapted to it to a moderate heat gradually, raised. Moisture speedily condensed in the neck of the retort, which increased and collected into small globules. I

This result was admitted by those who defended the new doctrine, when the experiment was performed in the manner ! have described--water being obtained, it was allowed" in inconsiderable quantity.” But, to obviate the conclusion, it was asserted, that this is water which has been absorbed by the salt from the atmosphere. This was affirmed by Sir Humphry Davy,

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* From the Transactions of the Royal Society of Edinburgh, vol, viii. part in + Nicholson's Journal, xxxi, 126.

who stated that the salt absorbs water in this manner to a very considerable extent ; that it is only from the salt in this state that water can be procured, and that when it is formed from the combination of the gases in a close vessel, and heated without exposure to the air, not the slightest trace of water appears, even when the experiment is performed on a large scale.

The reverse of this I was able to demonstrate by further experimental investigations. It was shown that the salt absorbs no moisture from the air in the common state of dryness and temperature in which the experiment is performed : when weighed immediately on its formation, in an exhausted vessel, it gains no weight from exposure, but remains the same after a number of hours; and when exposed to the air in the freest manner, it remains, after many days, perfectly dry. It was further shown, that when the other circumstances of the experiment are the same, it yields no larger portion of water when it has been exposed to the air than it does without this previous exposure. And, lastly, it was proved, that when the salt has been formed, and is heated without the air having been admitted, water is obtained from it. This last result was even at length admitted by those who had advanced the opposite assertion, in an experiment performed with a view to determine the fact. The quantity of water was indeed less than what is procured in the other mode; but this was obviously owing to the circumstances of the experiment being unfavourable to its expulsion, more particularly to the difficulty of applying a regulated temperature to a thin crust of salt, so as to separate the water without volatilizing the salt itself

, and to the effect arising from the whole internal surface of a large vessel being encrusted with the salt, so that if the heat is locally applied, the aqueous vapour expelled from one part is in a great measure condensed and absorbed at another ; or if the heat is applied equally, is retained in the elastic form, and, as it is cooled, is equally condensed. Accordingly, when the experiment was repeated, obviating these sources of error as far as possible, the water obtained was in larger quantity. And as no fallacy belongs to the conducting the experiment in the more favourable mode in which it was first performed (the assertion of the absorption of water from the air being altogether unfounded), the quantity procured in that mode is to be regarded as the real result.*

The argument was maintained that the water might be derived from hygrometric vapour in the gases submitted to experiment. This it was easy to refute. Dr. Henry had shown that ammonia, after'exposure to potash,and muriatic acid after exposure to muriate of lime, retain no trace of vapour whatever; and these precautions had been very carefully observed. The assertion was brought forward too only to account for the minute quantity of water

* Nicholson's Journal, xxxii, 186, &c.; xxxiv. 271.

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VEGETABLE Food.

ANIMAL FOOD. 2. From the Cæcum.

2. From the Cæcum. Of a yellowish brown colour, Of a brown colour, and very and of a thick and somewhat slimy consistence. Smell very slimy consistence.

Did not offensive and peculiar. Coacoagulate milk.

gulated milk. A. Water, quantity not as- A. Water, quantity not ascertained.

certained. B. Combination of mucous B. Combination of mucous principle, with altered alimen- - principle, with altered alimenttary matters insoluble in acetic

ary matters insoluble in acetic acid, and constituting the chief acid, and constituting the chief bulk of the substance.

bulk of the substance. C. Albuminous matter, none.

C. Albuminous matter, a

distinct trace. D. Biliary principle, some- D. Biliary principle, somewhat altered in quantity, nearly what altered in quantity, nearly as above.

as above. E. Vegetable gluten? none; E. Vegetable gluten? none; but contained a principle solu- but contained a principle soluble in acetic acid, and precipi- ble in acetic acid, and precipitable very copiously by oxalate table very copiously by oxalate of ammonia.

of ammonia. F. Saline matters, nearly as F. Saline matters, nearly as above.

above, G. Insoluble residuum, in G. Insoluble residuum, in small quantity

small quantity.

ob diet! 3. From the Colon.

3. From the Colon: 1 Of a brownish yellow colour,

Consisted of a brownish, of the consistence of thin mus- tremulous, and mucus-like fluid tard, and full of air bubbles. part, with some whitish flakes, Smell faintish and peculiar, somewhat like coagulated albusomewhat like raw dough. Did men, suspended in it. Smell not coagulate milk.

faintish, and not peculiarly fætid, like bile. Coagulated

milk. A. Water, quantity not as- A. Water, quantity not ascertained.

certained. B. Combination of mucous B. Combination of alimentprinciple with altered aliment- ary matter in excess with muary matters, the latterin excess,

cous principle, insoluble in insoluble in acetic acid, and acetic acid, and constituting constitutin

the chief bulk of the chief bulk of the substance. the substance.

C. Albuminous matter, none. C. Albuminous matter, none.

D. Biliary principle, nearly D. Biliary principle, nearly as before in all respects.

as before in all respects.

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VEGETABLE FOOD.

ANÍMAL FOOD, E. Vegetable gluten? none,

E. Same as in the cæcum but contained a principle soluble above-mentioned. in acetic acid, and copiously precipitable by oxalate of ammonia as in the cæcum. F. Salts, nearly as above. F. Salts, nearly as above.

Only some traces of an alkaline

phosphate were observed. G. Insoluble residuum, less G. Insoluble residuum, a than in the cæcum.

flaky matter in very minute

quantity. 4. From the Rectum.

4. From the Rectum. Of a firm consistence, and of Consisted of firm scybala, of an olive-brown colour inclining a dark brown colour inclining to yellow. Smell fætid and to chocolate. Smell very fetid. offensive. Did not coagulate Milk was coagulated by the milk.

water in which it had been

diffused. A. Water, quantity not as- A. Water, quantity not ascertained.

certained. B. Combination, or mixture B. Combination, or mixture of altered alimentary matters in of altered alimentary matters in much greater excess than in much greater excess than in the colon, with some mucus ;

either of the other specimens, insoluble in acetic acid, and with some mucus ; insoluble in constituting the chief bulk of acetic acid, and constituting the fæces.

the chief bulk of the faces. C. Albuminous matter, none.

C. Albuminous matter, none. D. Biliary principle, partly D. Biliary principle, more b changed to a perfect resin. considerable than in the vege

table fæces, and almost entirely Dis:

changed to a perfectly resinous

like substance. E. Vegetable gluten? none;

E. Vegetable gluten? none; but contained a principle similar but contained a principle similar to that in the cæcum and colon. to that in thę cæcum and colon.

F. Salts, nearly as before. F. Salts, nearly as before.

G. Insoluble residuum, con- G. Insoluble residuum, consisting chiefly of vegetable sisting chiefly of hairs. fibres mixed with hairs.

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Examination of the Contents of the Duodenum of the Ox. This had been kept for some time before examination, and appeared to contain an unusually large proportion of bile, Its colour was greenish, and it was of a ropy consistence, apparently holding suspended in it some solid matters, which, after a

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little time, subsided to the bottom." Its taste was hitter, its. smell faintish, and somewhat similar to bile. Sp. gr. 1.023:2 ilt exhibited very faint traces of an acid, and coagulated milk.completely, when assisted by a gentle beat. s Nearly the same method was adopted in the analysis of this, as of the other spez cimens before mentioned, and the results were as follow 1979

A, Water.

B. Gastric principle, united with alimentary matters, and apparently constituting the chyme, mixed with excrementitious matter....

C. Albuminous matter
D. Biliary principle

4:41 E. Picromel ?.

14
F. Vegetable gluten, or extract
G. Saline matters ...
H. Insoluble residuum

03

स 100.0

{ The chymous matter was less in quantity, and the biliary principle much greater in this specimen than in any of the others. There was also a substance present (E) which have called picromel. It was of a brown colour, and gummy consistence. Taste, first bitter, and afterwards sweetish. Soluble in water, but perfectly insoluble in alcohol. It was obtained after the action of the alcohol by boiling the residuum in distilled water It was not precipitated by the oxymuriate of mercury, bat icemo pletely so by the subacetate of lead. Hence it appeared to be à sort of altered mucus, or rather, perhaps, a combination of mucus with a little biliary principle, which the alcohol was inoa pable of removing. Indeed so intimately does the biliary principle unite with all animal substances with which it comes in contact: that it can scarcely ever be again entirely separated. The inson luble residuum (H) was chiefly vegetable fibres. $129995

Examination of the Contents of the Duodena of Rabbits. The animals were the same as those in which the phenomena of digestion above described were observed ; and the experiments! -for ascertaining the properties of the contents of their duodena were similar to those made upon the duodenal contents of the dogs and ox; and need not, therefore, be repeated. The duodenum of the rabbit, fed on a mixture of bran and oats above mentioned, at its commencement, contained chiefly a greeniste yellow glairy fluid, full of air bubbles, with a small portion only. of the insoluble parts of the food. This yielded decided evidence of the existence of a true chymous or albuminous principle. A little lower down in the duodenum a similar glairy fluid was observed, but it was more free from air bubbles, and seemeditoi -contain a larger proportion of an albuminous principle. In short, the quantity of albuminous matter was found to increase to the

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