ON 
DETECTING THE PRESENCE 
OF 
BW 5 Athen Sem [ihe 
PARTICULARLY IN REFERENCE TO THE EMPLOYMENT 
OF “MARSH’S TEST.” 
BY HENRY HOUGH WATSON, 
(CORRESPONDING MEMBER OF THE SOCIETY.) 
(Received February 2nd—Read February 9th, 1841.) 
In cases of poisoning by arsenic, it frequently 
happens that, after death, adhering to the stomach, 
or interspersed in the contents of the stomach, 
are to be found portions of a heavy white powder, 
in quantity so great that it can be collected and 
submitted to the process of reduction by carbo- 
naceous matter, as well as part of it exposed to 
the action of those other chemical operations 
usually resorted to on such occasions :—in these 
instances, there is no difficulty in arriving at a 
positive conclusion, that the white powder ope- 
rated upon is oxide of arsenic. It is not always, 
