384 Eliot and Storer on Arsenic as 
maceutical chemistr 
cently Blondlott and Leroy,§ assert that the presence of the insoluble sul- 
phid of arsenic cannot be recognized by Marsh’s test, and that arsenic 
y the unavoidable presence of this gas. é 
Arsenic in American Acids —We have tested four ditieceas err 
ial oi 
American sulphuric acid, of which two were commerce of vitrol, 
d two were sold a8 chemically pure acids, The test applied to these 
acids was always the same, and may be described once l 
ce of arsenic. The deposits obtained from these two acids were h 
larger than that produced by the 0:000015 gram. of arsenic used 1n 1” 
urth experiment on the delicacy of the reaction, but, on th 
only a small quantity (from 25 to 50 ¢. c.) of the acid could be em 
in a single experimen of 
he arsenic which is eliminated from these acids during the iene 
purification with chlorhydric acid may easily be collected, and exhibi 
*M. Signoret (Taylor on Poisons, 2d Edition, 1859, London, p. 396) states eg 7 
has d nbatiee deposits with only the 200,000,000th part of arsenic 9 
liquid; but it is not clear from such a statement what the exact amount of arse 
in the apparatus was which enabled him to obtain deposits,—a very mate 
Jour. de Ch. Méd., [2], v, 380, in Berzelius’s Jahresbericht, 1841, xx, 192. 
_ $ Comptes Rendus, 1857, xliv, 1222, & Ibid., 1859, xlix, 46? 
New Phil. Jour., xxxv, 235. . 
