170 
MEDICO-LEGAL CONTRIBUTIONS ON ARSENIC. 
It may also be said that, while the special works on poisons 
contain detailed information regarding the various tests, 
they are deficient in any systematic method of procedure 
applicable to those cases where the particular poison is 
unknown. 
Aside from text-books on chemical analysis, and a single 
one on the detection of poisons, there is nothing easily ac¬ 
cessible to medical men in this country that furnishes detailed 
information upon this subject. The design of the first part 
of this paper (which bears no claim to originality, but is a 
compilation from various sources), then, is to give the 
method pursued in the investigation of the cases hereafter 
reported—a general mode of procedure in all cases of metallic 
poisoning (ensuring the detection of the various toxical 
agents), with special reference, however, to arsenic; and 
again give a systematic plan, whereby the material can be 
most properly prepared for obtaining the various tests, 
together with the brief description of the more characteristic 
chemical reactions for arsenic. 
Part I.— The Detection of Arsenic. 
I. General Considerations. 
1. Chemical Evidence .—The chemical evidence in cases of 
supposed poisoning is generally regarded as the least falla¬ 
cious of all branches of proof. Owing to the labours of 
Orfila, Fresenius, Otto, Stass, Flandin, and others, in the 
detection of poisons, the subject has become so far developed 
that, in the majority of cases, a charge of poisoning may be 
satisfactorily decided by the results of a chemical examination. 
This opinion is entertained not only by professional chemists, 
as well as by intelligent medical men, but also by courts of 
justice, so that commonly the chemical detection of a poison 
is deemed necessary before a conviction can be obtained in a 
charge of poisoning. 
But it must be said that not unfrequently too much 
reliance is placed upon chemical evidence, many deeming it 
unsafe to convict where this evidence is wanting. This is, 
however, a narrow view, and indicates an ignorance of 
toxical science. Simply because poison is found in certain 
remains, it does not necessarily follow that it was the cause 
of death ; the symptoms and post-mortem appearances may 
prove the contrary; nor does the absence of poison in the 
dead prove that death was not occasioned by poison. 
In this country few, if anj’, individuals have been con¬ 
victed of the crime of poisoning where the poison was not 
