152 
ON ARSENIURETTED HYDROGEN. 
ART. XXVI. — OBSERVATIONS ON ARSENIURETTED HY- 
DROGEN. By M. Henri Rose. 
{Extracted from Comptes Rendus of the Berlin Academy.) 
We employ to detect the presence and destroy the slightest 
traces of arseniuretted hydrogen, a solution of deutochloride 
of mercury, in which this gas produces a precipitate of a yel- 
low color, bordering on brown, a character which discrimi- 
nates this precipitate from that obtained by phosphuretted hy- 
drogen from the same solution. 
The composition of this precipitate is wholly unknown. 
Stromeyer appears to be the only chemist who has examin- 
ed it. According to him, arseniuretted hydrogen forms, with 
deutochloride of mercury in solution, at first arsenious acid 
and protocjiloride of mercury, afterwards an amalgam of ar- 
senic. The precipitate is gradually decomposed under a 
large quantity of water; it becomes black, and finally con- 
sists solely of mercury, in a state of minute division ; the su- 
pernatant liquid contains hydrochloric and arsenious acids. 
This decomposition is analogous to that which water effects 
on the precipitate formed by phosphuretted hydrogen, in a 
solution of deuto-chloride of mercury; this precipitate 
changes into mercury and phosphorous and hydrochloric 
acids. Nevertheless, this latter decomposition takes place 
more rapidly than the preceding. 
The two precipitates are similarly affected, when treated 
with nitric acid ; they change, by the assistance of a slight 
heat, into protochloride of mercury, and at the same time the 
arsenic and the phosphorus are oxidized. 
This similarity of reaction would appear to indicate simi- 
larity of composition ; this is confirmed by analysis ; the ar- 
senical precipitate according to analysis, is represented by the 
formula. 
As 2 Hg 3 + 3HgCl*. 
