304 EXPERIMENTS AND OBSERVATIONS 
view under which it may be regarded as present, as an adven- 
titious ingredient. The acid having a strong attraction to 
water, may be supposed, in the processes in which it is usually 
prepared, to retain a portion not strictly essential to its con- 
stitution as muriatic acid gas, but still chemically combined,— 
that is, combined with it with such an attraction as to be libe- 
rated only when it passes into other combinations, and it may 
be this portion which is obtained in the action of metals on 
the gas ; the other portion, that essential to the acid, being suf- 
ficient to produce the requisite oxidation of the metal. 
The question with regard to the existence of water in this 
state, Gay Lussac and Tuxnanp' have already determined. 
From an extensive series of experiments, they found reason to 
‘conclude, that muriatic acid gas, in whatever mode it is pre- 
_ pared, is uniformly the same. From the quantity of hydrogen 
gas which combines with oxymuriatic gas in its formation, it 
follows, that it contains 0.25 of water, essential to its constitu- 
tion. But the gas obtained by the usual processes, afforded, 
they found, exactly 0.25 of water, when transmitted over. oxide 
of lead, or combined with oxide of silver ; and the same com- 
pounds are formed, as by the action of oxymuriatic acid on sil- 
ver and lead in their metallic state. They prepared muriatic 
acid gas, by heating fused muriate of silver with charcoal mo- 
derately calcined. It contained just the same quantity of wa- 
ter as muriatic acid obtained from humid materials, as it af- 
forded the same quantity of hydrogen from the action of po- 
tassium. And instead of being capable of receiving the small- 
est additional portion of water, a single drop of water being in- 
troduced into three quarts of it, did not disappear, nor even 
diminish, but, en the contrary, increased in volume *, These 
; facts 
(6h SS eee ta ee, 
* Recherches Physico-chimiques, t. ii. p. 133. 
