THE DETERMINATION OF ARSENIC IN URINE. 

 By Charles Robeet Sanger and Otis Fisher Black. 



Presented January 9, 1907. Received August 20, 1907. 



Some years ago one of us (S.) had occasion to make a number of 

 analyses of urine in cases of suspected chronic arsenical poisoning.^ In 

 looking up the literature of the subject at that time, it was found that 

 the analysis of the urine in case of chronic arsenical poisoning had 

 been comparatively rare. In the twenty-three cases cited by Sanger 

 in which the urine had been examined and the methods of analysis de- 

 scribed, the latter were generally open to adverse criticism. They were 

 usually tedious and often involved the use of many reagents, thereby 

 adding to the possibility of introduction of arsenic. The amounts of 

 arsenic found, in the absence at that time of any method for the deter- 

 mination of small quantities, could only be judged from the descrip- 

 tions of the mirrors, but probably did not exceed 1 mg. of arsenious 

 oxide per liter, and in many cases must have been less than 0.1 mg. 

 In the only analysis found in which quantitative results were given, 

 the amount was stated to have been 16.8 mg. in 1700 c.c, but the 

 method of analysis was not given, hence this case was not included in 

 the twenty-three above mentioned. 



The method used by Sanger for the treatment of the urine was based 

 on that proposed by Gautier ^ for the general treatment of animal 

 tissue. To a measured volume of urine was added about one tenth the 

 volume of concentrated nitric acid, and the whole was evaporated over 

 a free flame. As the mass neared drjmiess the flame was lowered, and 

 more acid was added, if necessary, in order to avoid carbonization at 

 the end. Deflagration often ensued, but it was thought that loss of 

 arsenic should not be feared in presence of excess of nitric acid. To 

 destroy the organic matter completely, the residue fi'om evaporation 

 was transferred to a smaller dish, treated with sulphuric acid, and 

 heated for some time, with addition of nitric acid, until a clear, white, 

 partly melted mass was obtained. The residue, free from nitric acid, 



1 These Proceedings, 29, 148 (1894). 



2 Ann. d.-Chim. et d. Phvs , [5] 8,384 (1876); Bull. Soc. Chim., [2] 24, 250 

 (1875). 



