126 DETECTION OF ARSENIC. 



easily be accomplished by adopting the processes which have 

 been before described, whereby the metal, or its compound, is 

 brought to our use dissolved in a simple colourless fluid. 



Tlie many and variously designed processes which have 

 been recommended by writers for the detection of arsenic liave 

 been purposely omitted. It would serve no useful purpose to 

 recapitulate them, and would merely tend to embarrass the 

 memory, witliout at all elucidating the subject. The pro- 

 cesses which are described are simple, easy of manipulation 

 and have answered in cases which faU within each of the 

 general divisions. So far as can be foreseen, they are adapted 

 to any case which may occur — they are at least as well adapted 

 to practice as any of the numerous processes by which the 

 books are overloaded. Indeed there has always seemed to me, 

 an appearance of empiricism in the processes laid down for the 

 detection of arsenic, as though an analysis of an inorganic, or 

 organic compound, supposed to contain arsenic, were to be 

 pursued upon other principles, than those by which ordinary 

 analysis is conducted. 



I do not wish to be understood as preferring any claim to 

 originality in these descriptions of the processes or the employ- 

 ment of any new means for the discovery of arsenic. I merely 

 wish to dispel the idea, which a student may acquire, that the 

 process for discovering arsenic, is a process -per se, and not 

 one based upon the general principles of chemical science, 

 an idea, which it is thought he may easily acquire, from the 

 manner in which the process is described in the books. 

 A regular routine is described through which ever\^ part 

 must pass, without any regard to the particular form and 

 circumstances under which it may be presented for examina- 

 tion, and which may be infinitely varied beyond the concep- 

 tion of the most fertile imagination. From this stricture the 

 excellent treatise of Dr. Christison on the detection of arsenic, 

 in his work on poisons must be exempted, as he has placed 

 the matter in its true light and properly excluded, or but casu- 

 ally mentioned, many of the obsolete and imperfect processes. 

 Having thus expressed my antipathy to a routine practice, I 

 must emphatically disclaim all desire of prescribing the course 

 which should be pursued, in the analysis of substances sup- 

 posed to contain arsenic. I claim to stand upon a broader 



