54 POISONS : THEIR EFFECTS AND DETECTION. [§ 37 . 
Process of Armand Gautier . 1 —Gautier has revived the old process 
of destruction of organic matter by sulphuric and nitric acids, with 
improvements in detail. 
Four grms. of pure sulphuric acid and 40 grms. of nitric acid 
(1-42 sp. gr.) are added to 100 grms. of the organic matter in a porce¬ 
lain dish. This is carefully heated until the entire mass assumes a 
chocolate colour ; 30 additional grms. of nitric acid are added little 
by little, taking care that before the addition of a fresh quantity the 
matters have a brown tint ; after the addition of the final quantity, 
the heat is continued until the contents are almost black, with 
commencing carbonisation. 
Next, 12 more grms. of nitric acid, three successive times, are added, 
after each addition pushing the carbonisation still further. The operation 
is finished when no more fumes are evolved and the carbon detaches itself 
from the dish. The mass is now rubbed to a powder in the dish itself 
by means of a pestle, and exhausted with from 250 to 300 c.c. of boiling 
water. This, after being filtered, contains the metals ; some sulphurous 
acid is added, and the whole is submitted to a current of SH 2 for 3 
hours, first at a temperature of 100°C. and then at ordinary temperatures. 
100 grms. of muscle leave from 2-5 to 3 grms. of carbon. The quantity 
of acid used in ordinary cases is therefore 4 grms. of sulphuric acid 
and 106 of nitric acid ; but should the matters be very fatty, more 
nitric acid is recommended. 
According to Gautier, the nitric acid acts on the chlorides, form¬ 
ing a nitro-hydrochloric acid, very poor in the latter (hydrochloric) 
acid, so that the chlorine is expelled with the nitrous products without 
a trace of arsenic chloride being formed. The excess of nitric acid also 
effectually prevents the formation of arsenic sulphide. 
Duret’s 2 method .—The materials are boiled in 10 per cent, sulphuric 
acid and ammonium persulphate, until all brown coloration has dis¬ 
appeared. It is best to add the ammonium persulphate in successive 
small quantities. This is an excellent and widely applicable process, 
and has been applied to urine and animal matters. 
PageVs process .—The older processes in which arsenic is distilled 
over as chloride of arsenic, according to the researches of Gautier, do 
not yield good results. Schlagdenkaufen and Pagel have, however, 
elaborated a process in which they state that in all cases the total 
amount of arsenic may be recovered in the form of chloride. 
The suspected organic matters are placed in a tubulated retort 
with a mixture of two parts of pure sodium chloride and one part of 
potassium bichromate; by means of a funnel tube provided with stopcock, 
pure sulphuric acid is allowed to drop little by little on to the mixture. 
A^violent^reaction occurs, chromous chloride (Cr0 2 Cl 2 ) gas being pro- 
1 A. Gautier, Bull. Soc. Chim ., 1903. 2 Compt. Rend., 167, 1918. 
