30 Dr. Murray's Experiments on. [JAN. 
other experiments in view which I conceived might afford more 
conclusive results. But it proves the point it was designed to 
establish, that water is obtained from the salt formed by the 
combination of the gases, as well as from the common sal ammo- 
niac. 
My attention having been thus recalled to the subject, I have 
again executed the experiment in its original and simplest form, 
that of obtainining water from the salt by heat alone ; and to 
this I was led more particularly, as it had occurred to me that 
a more perfect abstraction of its water might be effected, by 
conducting the experiment in an apparatus somewhat on the 
principle of the instrument invented by Dr. Wollaston, which he 
named the Cryophorus. In a retort of the capacity of seven 
cubic inches, fitted with a stop-cock, and exhausted, 60 cubic 
inches of ammoniacal gas were combined with the requisite 
quantity of muriatic acid gas, each previously carefully dried, the 
former by exposure to potash, the latter by exposure to muriate 
of lime. The stop-cock was then detached from the retort ; the 
excess of ammoniacal gas was removed by a caoutchouc bottle, 
and replaced by atmospheric air; the salt was pushed down 
from the neck ; and it was connected with another similar retort, 
the joming of the two being secured by cement. This last 
retort was also fitted with a stop-cock adapted to a tubulature at. 
its curvature, and heat being applied to it, a little of the included 
air was allowed to escape. It was then placed in a mixture of 
muriate of lime and ice ; while the other, containing the munate 
of ammonia, was placed in warm oil. ‘The heat of this was 
raised to 420° of Fahr. moisture condensed at the upper part of 
the neck, when the heat had been raised to 220°, and continued 
for some time to increase. It then diminished, from the conti- 
nued application of the heat, carrying it forward imto the cold 
retort; and at the end of the experiment, a considerable part of 
the body of this was encrusted with a thin film of ice. This 
result, therefore, coincides entirely with what had been before 
obtained.* 
* A foreign chemist, who has continued tosupport the old doctrine of the nature 
of muriatic acid, has observed (Annals of Philosophy, viii. 204) that the water of 
the muriatic acid gas cannot be supposed to be obtained by the combination of the 
acid with ammonia; for no neutral ammoniacal salt, he adds, can be obtained free 
from water, and the water of the acid gas becomes the water essential to the salt. 
I did not think it necessary to makeany reply to this observation, founded entirely, 
as it appeared to me, on a mistaken assumption. But I may take this opportunity 
of remarking, that there is m0 necessary truth in the supposition that the ammonia- 
cal salts must contain water which they cannot yield. When acids combine with 
bases, the water of the acid does not necessarily remain in the compound. On the 
contrary, itis capable of being driven off from the greater number of them, by an 
elevated temperature; and there is no principle on which it can be inferred that 
ammonia should inthis respect be different from other bases. That it is incapable, 
as the same chemist remarks (4nnals, vii. 434), of combining with a dry acid,,so 
as to forma neutral compound, is of no weight ;. for the same thing is true of other 
bases, which yet, when combined with such an acid by the aid of water, allow this 
water to escape from the combination. He himself observes, that well-burned 
