264 EXAMINATION FOR ARSENIC 



drated sesquioxide of iron, administered as an antidote 

 in a suspected case of poisoning, might have contained 

 arsenic, unless prepared with great care. Or the 

 arsenic may have been administered as a remedy 

 (especially as a secret medicine). When bodies have 

 been exhumed, it becomes necessary to test the earth 

 with which the coffin has been in contact, since it 

 sometimes happens that soils, especially such as are 

 ferruginous, contain appreciable quantities of arsenic, 

 which might have entered into the body. 



Various methods are employed for the modification 

 or destruction of the organic matters, with a view to 

 the extraction of the arsenic. 



1. When the substance is in the form of a paste, as 

 in the contents of the stomach and in the faeces, 

 chlorine-gas is passed to saturation. The chlorine is 

 prepared by means of sulphuric acid and manganese, 

 which have been previously tested, and is washed by 

 passing through a small but high column of water. 

 In order to assist the action, the mass may, at the same 

 time, be gently heated. Lastly, when it is completely 

 saturated with gas, coagulated, and bleached, the mix- 

 ture is heated nearly to ebullition to expel the excess 

 of chlorine, and the solution, which must contain the 

 arsenic, is filtered through paper free from smalt. 



2. The stomach and intestines, with their contents, 

 are cut into fine shreds, placed in a porcelain dish, and 

 the whole mass uniformly mixed. About J is then 

 set aside in a clean covered glass, in case any accident 

 should happen to the remainder. The mass is then 

 treated with a moderately concentrated solution of 

 potassa, and heat applied until it is entirely or almost 

 entirely dissolved. Only a small quantity of potassa 

 is necessary for this purpose, and the potassa should 

 therefore be gradually added to the mixture, so as to 

 avoid an excess, which would interfere with the sub- 

 sequent operations. The solution is afterwards slightly 



