732 
COLOUR-TESTS FOR STRYCHNIA, ETC. 
specifying three principal colours passing into each other by 
insensible gradations. The first and most characteristic 
colour is a rich blue or purple, the second a claret, and the 
third a bright orange. The first colour may be compared to 
the bloom of the Orleans plum, the second to the mulberry, 
the third to the peel of the sweet orange. This is the suc¬ 
cession of colours in the majority of experiments, but the 
exceptions to the rule are very numerous, and will be pre¬ 
sently more particularly mentioned. 
When the colour-developing test is applied to the solution 
of strychnia in strong sulphuric acid, and immediately stirred 
into it with a glass rod or spatula, the first colour is well 
marked, and lasts for from half a minute to forty-five seconds; 
the second colour during one, two, or three minutes; and the 
third colour for several hours or days. But when the acid 
solution is diluted with distilled water, or the colour- 
developing test is applied in solution, the first colour only 
may be produced, and that indistinctly and transiently, or 
the test may wholly fail. It will succeed in developing all 
the colours only when the quantity of the alkaloid is con¬ 
siderable. It should also be understood that, even when the 
experiment is made in the manner just described, the results 
are by no means uniform. Some of the exceptions to the 
rule will appear in the issue of the comparative experiments 
now to be detailed. 
I made two series of these experiments. I first compared 
the peroxide of manganese with the peroxide of lead. I then 
made a similar comparison of the three soluble salts, the bi¬ 
chromate of potash, the ferricyanide of potassium, and the 
permanganate of potash; and having selected from each 
group the best and most characteristic reagent, proceeded to 
compare the two so selected with each other. 
I made the two series of experiments in the same way. I 
used in both cases a number of small slabs of white porcelain, 
equal drops of the acid solution of strychnia (-2o<jth grain to 
the drop), and equal fragments of the reagents. 
[To he continued .) 
