c. Ammonia fails to produce a precipitate, or redissolves permanently the one formed.
The solubility of the alkaloid in ether is ascertained. If it be soluble, it may consist of aconitine, atropine or codeine; if insoluble, of emetine or morphine.
The alkaloid is soluble in ether.—If bichloride of platinum fails to precipitate the hydrochlorate from a neutral solution of the alkaloid, and sulphuric acid causes it to assume a yellow color which subsequently changes to a reddish-violet, it probably consists of aconitine.
In case bichloride of platinum causes a precipitate and sulphuric acid fails to produce the yellow coloration referred to above, the presence of either atropine or codeine is indicated. In order to decide which of these bases is present, the substance is dissolved in pure chloric acid and the solution allowed to spontaneously evaporate. If the alkaloid is deposited during this operation, it probably consists of atropine.
If this is not the case, there is reason to infer the presence of codeine.
The alkaloid is insoluble in ether.—If it dissolves in acetone it probably consists of emetine.
If acetone fails to dissolve it, the presence of morphine.
is indicated.
The following confirmatory tests should be applied: (1) Upon treating the substance with nitric acid, it acquires a blood-red color; (2) the addition of a solution of a persalt of iron produces an evanescent blue coloration; (3) chloride of gold is colored blue, when treated with the alkaloid; (4) the substance reduces iodic acid: this reduction is detected by adding to the acid a little starch-paste, which turns blue upon the liberation of the iodine; (5) permanganate of potassa, if heated with the substance, is reduced and acquires a green color.
IDENTIFICATION OF DIGITALINE, PICROTOXINE AND COLCHICINE.
It has already been remarked that in exhausting the first acid solution with ether—previous to the neutralization, according to Otto's method—colchicine, a weak alkaloid, digitaline, an indefinite mixture, picrotoxine (which appears to possess the properties of an acid), and traces of atropine, pass into solution.