Chemistry and Physics. . 143 
5 parts of sulphur gradually with constant stirring. This powder 
has the composition (Ag,S.Ag,SO,). e compound which 
mula Ag,As.(AgNO,),. Hydrogen phosphide gives a precisely 
similar body Ag,P.(AgNO,), ge? 
Ag,Sb.(AgNO,),. With reference to the toxical application of 
this reaction the authors say that the lemon-yellow spot produced 
by arsenic, with its brown-black edge, becoming immediately 
black when moistened with water, is easily distinguished from 
the more greenish-yellow spot given by sulphur, which water does 
not affect, and the antimony spot which shows on its brownish 
edge a gray-white mirror. The spot produced by phosphorus is 
not easily distinguished from that of arsenic. But since phos- 
phoric acid is not reduced to hydrogen phosphide by nascent 
free air. Before the author’s results are given certain criticisms 
of the results of previous observers are made, Determinations of 
LeRoux in gun-fire experiments would ive closer results if they 
were corrected for this divergence.— Phil. Mag., Dec. 1883, pp. 
447-455, J, 7. 
