36 Orobanche Virginiana, 
who had passed some time at Fort Pitt, was known to have collect- 
ed the plant for the purpose. I believe it to be a fact sufficiently 
established, that the basis, or perhaps rather the most active part, 
of Martin’s powder, was the oxyd of arsenic. This has been shown 
by a chemical examination of the powder, and by other circum- 
stances nearly as decisive. Thus comatose affections, such as are 
known to be induced by arsenic, have been induced by the powder 
of Martin, even when externally applied in cancerous ulcers. A case 
of this kind came under the notice of a physician in Philadelphia. 
The patient seemed to fall a victim to the application of the medi- 
cine. 
“ But the powder of Martin did not consist entirely of the oxyd of 
arsenic. This is certain. I believe it to be certain also, that he 
combined with the arsenic, a vegetable matter; and from what has 
been said, it would seem not entirely improbable, that this vegetable 
was the Orobanche Virginiana, 
“It may be said, and it is not,impossible, that Martin added the 
¥egetable matter merely to disguise the arsenic, reposing, at the. 
same time, all his confidence in the arsenic alone. I think it more 
probable, however, that the superior efficacy of Martin’s powder, 
and of the powders in the hands of other empirical practitioners, 
has been, in part, owing to the addition of something to the arsenic. 
If there be no foundation for this suspicion, how has it happened, 
