52 POISONS : THEIR EFFECTS AND DETECTION. [§ 37 . 
there is sufficient material to allow of division into three parts—one for 
organic poisons generally, one for inorganic, and a third for reserve in 
case of accident. When such is the case, although, for organic principles, 
the process of vacuum distillation just described still holds good, it will 
be very much the most convenient way not to use that portion for 
metals, but to operate on the portion reserved for the inorganic poisons 
as follows, by destruction of the organic matter. 
METHODS OF DESTROYING ORGANIC MATTER WHEN 
SEARCHING FOR MINERAL POISONS (ESPECIALLY 
ARSENIC). 
§ 37. Destruction by Heat. —Of all methods, destroying by heat alone 
or in a current of oxygen is the most perfect ; always provided that 
the apparatus is so arranged that volatile metallic vapours can be con¬ 
densed or otherwise recovered. 
G. Bertrand, 1 in researches on the presence of arsenic in the animal 
tissues, burns the organic matter by means of compressed oxygen in 
Berthelot’s calorimetric bomb. From 1-2 grms. of the substance, 
previously dried, is placed in the bomb ; and the combustion is initiated 
by a very small shred of fulminating cotton in a platinum loop, through 
which is passed an electric current. 
Where necessary, the product of several combustions is accumulated 
in the same bomb. The bomb is then washed out with water. The 
water contains traces of nitric acid produced in the combustion, which 
it is usually best to evaporate off. 
The objection to the process is the expense of the apparatus, the 
cheaper enamelled bombs in commerce, according to Bertrand, always 
containing traces of arsenic ; besides which, only a very small quantity 
of the substance can be dealt with at one operation. On the other hand, 
the advantages are obvious. The combustion is complete, and a solution 
can be readily obtained suitable for treatment by hydric sulphide or by 
Marsh’s apparatus. 
Yerryken 2 places 5-10 grms. of the previously dried organic matter 
in a combustion tube, into which is led dry oxygen by three small tubes 
of different length, in order to distribute the gas equally ; the tube is 
connected with a series of bulbs charged with water. The tube is very 
carefully heated to a dull red heat on each side of the substance ; then 
the substance itself is heated very carefully, in such a way as to avoid 
brisk inflammation of the mass ; on cooling, the tube is washed out 
with hot nitric acid, the water in the bulbs added, and thus a nitric 
acid solution obtained. 
1 G. Bertrand, “ Emploi de la bombe calorimetrique pour demontrer l’oxistence 
de l’arsenic dans Torganisme,” Compt. Rend., 1903. 
2 Journ. de Pharm. d' Anvers, 1872. 
