with Observations on-its Chemical Constitution. 111 
ment, muriate of ammonia was passed in vapour through an 
ignited porcelain tube alone. Water was obtained in larger 
quantity than when the salt had been exposed to a heat short of 
its volatilization ; and even the salt which had yielded water by 
that operation, afforded an additional quantity in ‘this mode,— 
a proof of the more perfect separation of the water by the effect 
of a higher temperature*. 
By all these results, then, I consider the existence ofiwater in 
muriate of ammonia, and of course in muriatic acid gas, as de- 
monstrated. 
Dr. Ure has lately laid before the Society the result of another 
mode of conducting the experiment,—that of subliming the mu- 
riate of ammonia over some of the metals at the temperature 
of ignition. Water is thus stated to be obtained in considerable 
quantity, with a production of hydrogen gas. 
No objection appeared to Dr. Ure’s experiment, except, per- 
haps, that the salt operated on was not that formed by the direct 
combination of its constituent gases, but the common sal am- 
motilac, in which water might be supposed to exist, either as an 
essential or an adventitious ingredient, as it is abundantly sup- 
plied to it in the processes by which it is formed. I had found, 
indeed, in some of my former experiments , that sal ammoniac 
yields no water when exposed to a heat sufficient to sublime it, 
but affords it only when exposed to a red heat by transmission 
of its vapour through an ignited tube;—that, therefore, (owing 
no doubt to its previous sublimation,) it contains apparently even 
less water than the salt formed by the combination of the two 
gases. Still, objections entitled to less consideration than this 
one, had been maintained in the course of this controversy, 1 
therefore thought it right to repeat the experiment, with the 
necessary precaution to obviate it, and to observe the actual re- 
sult. 
Thirty grains of muriate of ammonia, formed from the com- 
bination of muriatic acid and ammoniacal gases, were put into 
a glass tube with a slight curvature. Two hundred grains of 
clean and dry iron filings were plaved over it. The tube was 
put in a case of iron with sand, and placed across a small fur- 
nace, so that the middle part, where the iron filings were, was 
at a red heat, the extremity terminating in the mercurial trough. 
The salt, from the heat reaching the closed extremity of the 
tube, soon passed in vapour through the ignited iron. Gas 
issued from the extremity, and moisture appeared in the cold 
part of the tube. A large quantity of gas was collected, which 
had the odour quite strong of muriatic acid, and was in part con- 
* Nicholson's Journal, vol. xxxi. p. 128. + Id. vol. xxxiy. p. 274. 
densed 
