290 EXPERIMENTS AND OBSERVATIONS 
was repeated, obviating these sources of error as far as pos- 
sible, 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 un-. 
founded), the quantity procured in that mode is to be regarded 
as the real result *. 
The argument was inaintained; that the water might be deri- 
ved from hygrometric vapour in the gases submitted to expe- 
riment. This it was easy to refute. Dr Henry had shewn, 
that ammonia after exposure to potash, and muriatic acid after 
exposure to. muriate of lime, retain no trace of vapour what- 
ever. And these precautions had been very carefully observed. 
The assertion was brought forward, too, only to account for the 
minute quantity of water obtained in that mode of conducting 
the experiment which affords the least favourable result, and 
were it even admitted to all the extent to which it can be sup- 
posed to exist, is inadequate to. account for the larger en 
obtained in the other. 
That the entire quantity of water contained in the muriatic 
acid gas, is not to be looked for, is evident from the nature of 
the ammoniacal salt, particularly its volatility, whence the due 
degree of heat to effect the separation of the water cannot be 
applied. If the other muriates yield the greater part of their 
water, only when raised nearly to a red heat, (which is the 
case), it is not to be supposed that muriate of ammonia ‘shall 
do so at a temperature so much lower, as that which it can su- 
stain without volatilization. What is to be expected, is a cer- 
tain portion of water, greater as the arrangements employed 
are better adapted to obviate the peculiar difficulty attending 
; ‘the 
* Nicrotson’s Journal, vol. xxxik p..196, &c. ; vol. -xxxiv. p. 271. 
