﻿10 THOMSON, Presence of Arsenic in the Body. 



There is, however, this to be said, that when 15 grammes 

 of other organs of the same body were tested, they proved 

 to be free from arsenic. Thus the spleen, liver, heart- 

 muscle, kidney, and rib bone were free from arsenic by my 

 test, but it was remarkable to note that the lung contained 

 considerably more arsenic than the thyroid gland, viz., 

 9-jjo-th, and the hair contained a great deal more than 

 either, viz., yjg-th of a grain per lb., whilst the brain 

 contained a very minute trace. 



All the experiments were made by heating the 

 portions of the various organs with sulphuric and nitric 

 acid. The organic matter which was most resistant to 

 oxidation being finally removed by dropping strong nitric 

 acid into the dark-coloured strong sulphuric acid solution 

 heated to the point of liberating white fumes, the result- 

 ing arsenic being finally contained in the 5 c.c. of strong 

 colourless sulphuric acid originally used, the whole of 

 the nitric acid having been finally removed by treating 

 the resulting sulphuric acid with water and evaporating 

 the water and nitric compounds to the point when the 

 sulphuric acid gave off heavy white fumes. The prints 

 of the mirrors obtained are shewn in Plate III., Fig. 2. 



Ordinary meat and the organs, such as the liver, 

 kidney, spleen, and lung oxidise easily under this treat- 

 ment, but the tissue of the brain resisted oxidation in a 

 remarkable manner. It evidently differed from other 

 tissues in containing some organic constituent which 

 remained intact in boiling strong sulphuric acid, and 

 only gradually disappeared on frequent treatment of the 

 highly heated acid (whilst giving off white fumes) with 

 strong nitric acid. 



I have to thank my assistant, Mr. Samuel Bateman, 

 B.Sc. (Vict.), for the care he has bestowed in carrying out 

 these experiments with me. 



