On Tests for the Discovery of Arsenic. 161 
have been more extended; but having come under the ob- 
servation of Prof. S. he thought proper to make that re- 
ference to them which has given rise to Dr. Cooper’s letter. 
Although I had the pleasure and advantage of attending 
parts of two of the courses of Dr. Cooper’s very able lec- 
tures, | have never,seen him apply the tests of arsenic, &c. 
For although I attended whenever my own duties gave me 
opportunity, it has so happened that the Doctor never spoke 
of arsenic or of tests for mineral poisons while I was pres- 
ent. A sufficient reason for the fact that Dr. C’s ‘‘ own test” 
for arsenic was not noticed in my experiments, is assigned, 
when itis said it had not then come to my knowledge. My 
object when I wrote, was to call the attention of those gen- 
tlemen who were addressed, to the inadequacy of the direc- 
tions laid down in the common books, in the hands of men no 
more acquainted with the subject, than most of our physi- 
cians to authorize an opinion, on which life or death should 
hang—without the actual exhibition of the poison in the me- 
tallic state. I believe that in many cases of sudden and ap- 
parently violent death, poisoning by arsenic would be im- 
mediately suspected, and if by the application of any tests 
by the rules laid down in the books, results such as were ob- 
tained by myself with the chromat of potash, should be ob- 
served, without further investigation it would be unhesita- 
tingly said, ‘“‘ This person was destroyed by arsenic.” It 
seemed also if the chromat of potash produced effects in 
these trials in appearance so much like arsenic, the other 
things either simply or combined might do the same, so that 
caution in deciding was by all means to be recommended. 
As to Dr. C’s objections to what he has denominated the 
first class of my experiments, he has gone on an erroneous 
supposition; for I not only agreedin his sentiment, that ‘‘no 
chemist could be led away by the ambiguity of colour, &c.” 
but my very words were, there seems no possibility of 
mistaking the one for the other. — “ 'T'o the second assertion 
(Dr. Cooper proceeds) 1 object that the statement in your 
summary is not quite accurate, as a matter of fact.” To 
this I reply, that all my statements were believed to be per- 
fectly accurate—there could be no object to induce an erro- 
neous statement—and although I have not compared them 
with the “summary,” J presume they will not be found to 
Vou. JTV.....No. 1. 
