COLOUR-TESTS FOR STRYCHNIA, ETC. 795 
The next object which I had in view was to subdivide these 
two large groups (Tables I and II) each into two or more 
smaller groups by some second test, which might also, per¬ 
chance, produce in some members of the two groups charac¬ 
teristic reactions, so as to eliminate or separate them at once. 
For this purpose I tried the effect of warming the acid solu¬ 
tion of the alkaloids by passing the porcelain slab through 
the flame of the spirit lamp, so as to raise the temperature of 
the liquid to a point short of that at which it gives off vapour. 
This subsidiary test answered its purpose completely; the 
group of substances in Table II, which had already given 
colours, more or less characteristic, with the cold acid, under¬ 
went further changes of colour, more or less peculiar; while 
the group in Table I, which had undergone no change with 
the cold acid, became subdivided into two leading groups, of 
which one continued without colour and the other under¬ 
went changes of colour more or less characteristic. In the 
instances of meconine and of aconitina, the colours developed 
proved to be peculiar to these substances, so as to lead at 
once to their elimination from the rest. 
By raising still further the temperature of the acid solu¬ 
tions to a point at which vapour was given off, a further 
separation into distinct groups or classes was found to take 
place. The six substances which stand first in order in 
Table I still remained colourless, while the remainder 
assumed tints more or less characteristic. Esculine and 
atropine; picrotoxia, santonine, and narcotine; amygdaline 
and naphthaline, formed themselves into three distinct 
groups; while strychnia, brucia, and morphia gave indica¬ 
tions of colour less distinct and characteristic. 
By this triple test of sulphuric acid, cold , warmed , and heated , 
the active principles contained in this division (Table I) 
have been either eliminated or split up into manageable 
groups, awaiting the application of further tests. It seemed 
natural to select, as the next test in order, nitric acid—a 
known characteristic test of brucia and morphia. By apply¬ 
ing this test to the several members of the table in succes¬ 
sion, codia was isolated from the group of six to which it 
belonged by the distinct yellow colour assumed by the acid 
solution. Emetine was, in like manner, isolated from the 
other members of the same group of six, by yielding with 
the acid a yellow-brown colour. Atropine, again, was dis- 
therefore, to state that the experiments on which the tables are founded 
were made in the winter, in a room with a tire, but in the morning, before 
the temperature of the room had been raised to a point approaching 
summer-heat; and that the acid employed was free from nitric acid. 
