616 DETECTING THE PRESENCE OF ARSENIC. 
antimony be present, a white precipitate is ob- 
tained, while, if neither arsenic nor antimony be 
present, the silver of the test liquor is reduced to 
the metallic state. 
In this modification of the application of Hume’s 
test, there is nothing whereby any of the doubt 
can be removed, as to whether a yellow precipi- 
tate produced is the consequence of the action of 
arsenious acid, or of phosphoric acid upon the 
test. See pages 600 and 601, of this volume. 
H. H. WATSON. 
June 2nd, 1841. 
