: 
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3 
with Observations on its Chemical Constiiution. 199 
the experiment, as equal to nearly one grain; or about one- 
fifth of the whole quantity of combined water, which muriati¢ 
acid gas is calculated to contain*. 
In all the preceding experiments, water has eek procured 
from muriatic acid gas. It is obvious, that such a result cannot 
be accounted for on the hypothesis, that it is the real acid free 
from water, a compound merely of chlorine and hydrogen. On 
the opposite doctrine, as muriatic acid in its gaseous form is held 
to contain water, it may be supposed to afford a portion of it, 
It may be maintained, however, in this, as it was in the ex- 
periment of obtaining water from the muriate of ammonia by 
heat, that the water produced is derived from hygrometric va+ 
pour in the gas. To obviate this, it is sufficient to recur to the 
fact established by the experiments of Henry and Gay Lussac, 
that muriatic acid gas contains no hygrometric vapour ; and to 
the obvious result in the experiment, that no quantity that can 
be assumed, would be adequate to account for the quantity ac- 
tually obtained. ‘The circumstances of the experiment, too, are 
such as to preclude any such supposition; and this more pecu- 
liarly so, than in the experiment of obtaining water from the 
muriate of ammonia by heat; for, in the present case, the acid 
is alone employed, while in the other there is an additional equal 
volume of ammoniacal gas, which may be supposed to afford a 
double quantity of hygrometric vapour. In the latter, both the 
gases are condensed into a solid product, aud any hygrometri¢ 
vapour may be supposed to be liberated; but in the present ex- 
periment, there remains the hydrogen gas, capable of containing 
hygrometric vapour, while the muriatic acid gas contains none ; 
* The action of the metals on the muriatic acid gas taking place in the 
above experiments at a heat comparatively moderate, it occurred to me, 
that they might exert a similar action with no higher heat on the acid, in 
muriate of ammonia, and that this might afford an easy mode of exhibiting 
the results. I accordingiy found, that on mixing different metals with sal 
ammoniac i0 powder, previously exposed toa subliming heat, and exposing 
the mixtare to heat by a lamp, so regulated as to be short of volatilization, 
the salt was decomposed, ammon jacal gas was expelled, and moisture con- 
densed in the neck of the retort; covering a space of several inches with 
small globules, and at length running down. ‘Ihe metals I employed were 
‘iron, zine, tin, and lead ; 100, 150, or 200 grains of each metal, dry, and 
warm, being mised with 100 grains of the salt, likewise newly heated. To 
obviate any fallacy from common sal ammonizce being employed, [repeated 
the experiment with the salt formed from the combination of its two con- 
stituent gases, and obtained the same result. But although this affords an 
easy mode of exhibiting the production of water, it is not favourable to 
obtaining a perfect result, the heated ammoniacal gas carrying off a con- 
siderable portion of the water deposited; and accordingly, the quantity, 
instead of increasing as the experiment proceeds, at length diminishes, and 
the ammoniacal gas deposits a portion of water in passing through mer- 
cury, or in being conveyed through a cold tube. 
and 
