332 Simple method for the 



process ; extreme simplicity, facility of execution, and absence 

 of the sources of inaccuracy. 



Reinsclr's discovery consisted in this : — that arsenic may 

 be separated from its solutions and deposited on copper leaf, 

 when the solution, acidulated with hydrochloric acid, is 

 boiled on that metal : and that, by gently heating the copper 

 on which the arsenic is deposited, this latter is sublimed in 

 the state either of arsenious acid or of metal, according to the 

 quantity present. This discovery was made known at a 

 time when Marshes beautiful method of separating arsenic 

 as arseniuret of hydrogen had been so refined upon, that, on 

 the authority of M. M. Danger and Flandin, metallic deposits 

 were said to have been produced when the arsenic formed 

 only the 2,000,000th part of the liquid examined,* and yet 

 the simplicity of Reinsclr's process, and the more complete 

 absence from it of sources of error, have given it a decided pre- 

 ference in the experience of every toxicologist of eminence. 

 Dr. Christison, in particular, has expressed his confidence in 

 Reinsclr's process, and states that he has followed it " with 

 great facility, certainty, and despatch, in several medico-legal 

 cases ;" that he has been able to detect at least the 250,000th 

 part of arsenic in solution ; and that it removes every particle 

 of arsenic from the liquid, so that none could afterwards 

 be detected by Marshes method. Dr. Christison even goes 

 so far as to say, that iC it is not subject to any fallacy." f 



A process of such simplicity is peculiarly adapted to the 

 circumstances under which toxicological analysis frequently 

 require to be undertaken in this country ; and the object of 

 my experiments has been to discover how far the same, or 

 similar processes, might be employed in the detection of the 

 soluble compounds of mercury and antimony. 



Where the ordinary apparatus and appliances of a labora- 

 tory are at hand, Marshes method, on account of its extreme 



* Journal de Chimie Medicale, 1841, p. 413. 

 t Christison on Poisons, 4th Edit. p. 272. 



