1819.] Muriatic Acid Gas. 29 
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 addi- 
tional quantity i this mode—a proof of the more perfect separa- 
tion of the water by the effect of a higher temperature.* 
By all these results, then, I consider the existence of water in 
muriate of ammonia, and, of course, in muriatic acid gas, as 
demonstrated. 
Dr. Ure has lately laid before the Society the result of another 
mode of conducting the experiment—that of subliming the 
muriate 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 ammo- 
niac, in which water might be supposed to exist, either as an 
essential, or an adventitious ingredient, as it is abundantl 
supplied 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, there- 
fore (owing no doubt to its previous sublimation), it contains 
apparently even less water than the salt formed by the combina- 
tion of the two gases. Still objections, entitled to less consider- 
ation than this one, had been maintained in the course of this 
controversy. I, therefore, thought it right to repeat the 
experiment, with the necessary precaution to obviate it, and to 
observe the actual result. 
Thirty grains of muriate of ammonia, formed from the combi- 
nation 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 placed over it. The tube was put in a 
case of iron with sand, and placed across a small furnace, 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 guite 
strong of muriatic acid, and was in part condensed by water ; 
the residue burned with the flame of hydrogen. The tube, for 
several inches, was studded with globules of water, and was 
bedimmed with vapour further. 1 did not prosecute the experi- 
ment, so as to ascertain the weight of water produced, as I had 
 Nicholson’s Journal, xxxi, 128. + Id. xxxiv. 274. 
