240 Medico-Legal Application of Riench's Test for Arsenic. 



Art. IT. — On the application of M. RiencKs test for the detec- 

 tion of Arsenic, to Medico-Legal Enquiries ; by D. P. Gard- 

 ner, M. D., Lecturer on Nat. Hist, in Rutgers Inst., Corr. Mem. 

 Lyceum Nat. Hist., New York, formerly Prof. Chem, &c. in 

 Hampden Sidney College, Va. 



The discovery of arsenious acid in complex fluids, has always 

 been an important problem in the science of toxicology, by rea- 

 son of its frequent use for criminal purposes. From the statistics 

 of the Viscount de Cormenin, it appears that between the years 

 1830 and 1840, three hundred and thirty five cases of poisoning 

 by arsenic, implicating four hundred and fourteen persons, were 

 investigated by the Parisian tribunals alone; and two hundred 

 cases more were ascertained, but not brought before the courts. 

 The use of this substance, in minute doses frequently given, to 

 produce a lingering death, has entailed upon the chemist the ne- 

 cessity of furnishing himself with the most delicate tests. For 

 as the certainty of detection increases, the temerity of the crimi- 

 nal also becomes greater, so that the cause of morality is directly 

 advanced by these researches. 



Numerous tests are recognized in medicine, but all of them, 

 with the exception perhaps of Mr. Marsh's, are of little value 

 in collecting the poison out of its solutions. This part of the 

 process is however the most important, for the profession have 

 unanimously agreed that no series of precipitations is satisfactory, 

 unless the metal be finally reduced. If sulphuretted hydrogen 

 be used, as recommended by Dr. Christison, for the precipitation 

 of the arsenic, we are embarrassed afterwards by the collection of 

 the matter thrown down, and then the reduction. This, and 

 many other processes, advised by writers, require much time, 

 with the use of materials not belonging to the medicines of a 

 country practitioner, and they are less delicate than the method of 

 M. Riench for the discovery of arsenic as a commercial impurity 

 in various fluids and reagents. The reader is referred to No. 126, 

 December, 1841, of the London, Edinburgh and Dublin Philo- 

 sophical Magazine, for an abstract of M. Riench's paper "on the 

 action of metallic copper on solutions of certain metals, particu- 

 larly with reference to the detection of arsenic" That article led 

 me to examine the utility of the test recommended in medico-le- 



