COLOUR-TESTS FOR STRYCHNIA, ETC. 
79 7 
I submit these tables primarily as specimens of Tables of 
Elimination , but also incidentally as tables which may prove 
serviceable to the chemist. I am not certain that they con¬ 
stitute the best aid which could be devised to the diagnosis 
of the alkaloids. 1 thought that they might, perhaps, admit 
of bei ng simplified by adding to the three columns headed 
“ sulphuric acid ” a fourth, showing the deposit of carbon 
resulting from the continued application of heat to the acid 
solution of the alkaloid. I tried this reaction in the case of 
fourteen alkaloids and active principles, comprising all the 
more active poisons of this class, together with the less im¬ 
portant principles, emetine and meconine, and found the 
alkaloids to differ from each other in the amount of carbo¬ 
naceous deposit. With strychnia, aconitina, and veratria, 
for instance, the deposit of carbon was less abundant than 
with brucia, morphia, atropia, and the other poisonous 
alkaloids. But the difference was not such as to justify me 
in using it as a diagnostic property. So also with the direct 
application of heat to the alkaloids themselves. Strychnia, 
morphia, atropia, cantharadine, meconine, picrotoxia, and 
delphinia, after melting, deposited but a scanty carbo¬ 
naceous ash ; while emitine, aconitina, and digitaline yielded 
an abundant ash; and brucia, elaterine, veratria, and sola- 
nine, yielded an ash intermediate in quantity. This test, 
again, though fairly applicable to the few cases in Table I, 
did not seem admissible as a diagnostic on a larger scale. 
Indeed, the tables, though carefully compiled and based on 
carefully conducted experiments, are open to the obvious 
objection that, with different specimens and different quan¬ 
tities of the alkaloids, and with different specimens of sul¬ 
phuric acid, we may obtain differences of tint, and more or 
less ready development of colour under increase of tempera¬ 
ture. The majority of the reactions, however, will, I believe, be 
found constant for all specimens of average purity. One alka¬ 
loid, hyoscyamia, w hich I was not able to procure, is omitted.* 
Of the two tables, Table I affords the best illustration of 
a table of elimination. For the sake of brevity, and for other 
reasons already explained, the figures 1, 2, 3, are added to 
the w r ords describing the colours developed by the tests. 
These figures indicate different degrees of intensity. In 
comparing strychnia with brucia, for instance, the figure (*) 
attached to the word “yellow” opposite strychnia in the 
third column means a faint-yellow colour, less in degree than 
that indicated by the figure ( 2 ) opposite brucia in the same 
* In the lectures at the College of Physicians a table was used which 
showed the colours actually produced by the action of the several reagents 
on these poisonous alkaloids and active principles. 
