MORPHIA PREVENTS COLOUR-TEST OF STRYCHNIA. 563 
results of the published experiments of different observers depend, I 
think, in a great measure, on their diverse modes of procedure, and 
therefore I feel justified in giving a precise account of— 
“ The Mode of Testing .—In every instance the material to be tested 
was employed in the solid form, such as the pure alkaloids or their salts. 
If it existed in solution, it was reduced to a solid consistence by evapo¬ 
ration in a test capsule, spontaneously, or by a very gentle heat. Having 
thus procured a solid substance, a small portion of it was placed upon a 
white plate, a drop of strong pure sulphuric acid was added, and tritu¬ 
ration was carefully made with a glass rod until the substance was 
dissolved. Then a small quantity of powdered bichromate of potassa, 
or of powdered ferricyanuret of potassium, was deposited on the plate, 
near the acid mixture but not touching it, and to the powder a minute 
drop of water was added—just enough to partly dissolve it—and then, 
with a pointed glass rod, a little stream was drawn from each of the 
solutions in such a direction as to cross each other. Immediately at the 
point of intersection the play of test-colours was beautifully manifested. 
When the bichromate was employed, the sequence of colours was blue 
or violet, instantly changing to purple, then gradually becoming red, 
and finally greenish-yellow. When the ferricyanuret was used, the 
colour was a rich bluish-purple, changing rapidly to a light rose-red. 
It is important to proportion the sulphuric acid to the amount of 
alkaloid, avoiding an excess beyond what is necessary to its perfect solu¬ 
tion; and, therefore, it is better to take the acid out of the bottle by a 
pointed glass rod, rather than to drop it from the lip.” 
To this follow the experiments, which it is not necessary 
for us to extract. 
Mr. J. $. D. Rodgers asserts that, as morphia is insoluble 
in benzol, and strychnine very soluble in that menstruum, it 
is consequently only necessary, where there is reason to sus¬ 
pect the presence of morphia, that the operator substitute 
benzol for ether or chloroform, and after charring any foreign 
organic matter by sulphuric acid, he will obtain a trustworthy 
and satisfactory result. 
Mr. Letheby, in a communication addressed to the editor 
of the journal whence the above is extracted, says : 
“ In the course of the last year or two a number of essays have been 
written on the influence of certain substances either in simulating or 
preventing the action of the nascent oxygen test for strychnia. Among 
the latter, morphia, tartar-emetic, common salt, sugar and gum have 
been spoken of as serious impediments to the colour-test. In truth, 
however, the only importance of those essays is the warning which they 
furnish to the unpractised operator of the dangers which he will incur 
in a bungling manipulation. To the practical toxicologist they are of 
no value except as indications of what mischief may be done to both 
science and justice by the meddlesome interference of an unskilful band. 
The extraction of strychnia from organic mixtures ought to give the 
alkaloid in a sufficiently pure state to negative the possibility of the 
fallacies or hindrances above mentioned. i\lost, indeed, of the so-called 
impediments to the action of the colour-tests are either soluble in ether 
and chloroform, which is the solvent used for the alkaloid, or they are 
so slightly soluble as to give but little trouble in the subsequent part of 
the analysis ; and when, as in the case of sugar, common salt, and 
