729 
ON THE COLOUR-TESTS EOR STRYCHNIA, AND THE 
DIAGNOSIS OE THE ALKALOIDS. 
Being the substance of part of the Croonian Lectures for 1861, 
delivered at the Royal College of Physicians. 
By William A. Guy, M.B. Cantab., Fellow of the College, 
and Professor of Forensic Medicine, King’s College, London. 
(Continued from p. 484.) 
There is still one point connected with the answer to the 
first of the four questions propounded in my first communi¬ 
cation which requires to be considered. The simple com¬ 
parative experiments which I have described appear to 
warrant the conclusion that the colour-developing substances 
are best applied in the solid form; but it is quite possible 
that the quantity of these substances used in the experiments 
may sensibly affect the development of the strychnia-colours. 
I accordingly put this question to the test of experiment. 
I placed four equal drops of the solution of strychnia in sul¬ 
phuric acid {200 grain to the drop) on each of three white slabs. 
1 added to the first group of four drops, bichromate of potash ; 
to the second, peroxide of manganese ; to the third, permanga¬ 
nate of potash; tothe first drop, in each case, a minute fragment 
of the test, and to the second, third, and fourth drops, a 
larger and larger fragment. This simple experiment yielded 
the following results:—With the bichromate of potash I 
obtained a perfect result with the smallest quantity of the 
salt, but with the larger quantities only the characteristic 
primary colour, the last secondary colour, or the colour which 
the mixture assumes after exposure for one or two minutes, 
was yellow-brown instead of bright brick-red. With the 
peroxide of manganese I obtained two perfectly characteristic 
results with the two smaller quantities, but with the larger 
quantities less characteristic secondary results. In the first 
two experiments with the smaller quantities the mixture 
assumed the usual clear, bright brick-red as the ultimate tint, 
while in the third and fourth experiments it continued for a 
long time to retain the second or mulberry tint. With the 
permanganate of potash the reaction was quite characteristic 
in the two experiments with the smaller quantities of the salt, 
but the third assumed, after short exposure, a pink, instead 
of a vermilion tint, and the fourth took on at once a rich 
red-brown tint, and, therefore, failed as a test. 
