212 COLOUlt-TESTS l’O R STRYCHNIA, ETC. 
peroxide of manganese black, the bichromate of potash orange 
coloured, the ferricyanide of potassium yellow or orange, 
and the permanganate of potash lilac. The peroxide of lead 
and the peroxide of manganese also colour sulphuric acid by 
admixture, and the bichromate of potash, ferricyanide of 
potassium, and permanganate of potash change the colour of 
the acid by solution. But it has been shown that the 
colours thus produced cannot possibly be confounded with 
the strychnia blue, and consequently form no valid ground 
of objection. 
The fourth of the five objections applicable to chemical 
tests in general certainly does not apply with any force to 
the colour-tests for strychnia; for 1 can state, as the result of 
experiments with a great variety of substances, vegetable and 
animal, including all the matters that are likely to remain 
mixed with strychnia after its extraction from the contents of 
the stomach or from the fluids and tissues of the body, and 
further with many mineral substances, including common 
salt, arsenious acid, tartar emetic, and corrosive sublimate— 
all these animal, vegetable, and mineral substances having 
been added in quantities far exceeding those in which they 
could possibly exist as impurities in strychnia extracted from 
the contents of the stomach or from the fluids and tissues of 
the body—that the colour-tests are little, if at all, affected 
by such admixtures. This observation applies to the per¬ 
manganate of potash equally with the bichromate of potash. 
For practical purposes the reaction which demonstrates 
the presence of strychnia may be described as a clear, rich, 
blue colour, developed by the colour-tests in a spot pre¬ 
viously treated by strong sulphuric acid without change of 
colour, the blue colour in question lasting long enough for 
perfect recognition, and then passing into other colours. In 
the absence of the blue colour we can affirm the probable 
absence of strychnia, but a mere flash of colour does not 
afford a degree of evidence upon which we ought to rely in a 
medico-legal inquiry. 
[To he continued.) 
