2. (Pure.)—a. Ipecacuanha (in coarse powder), 1 part, is digested for 24 hours in distilled water, 10 parts; together with calcined magnesia, added in slight excess; the deposit is then thrown on a filter, washed carefully with very cold water, and dried; it is next dissolved in rectified spirit and neutralised with dilute sulphuric acid; the filtered solution is decoloured with animal charcoal, again filtered, and again precipitated by digestion with magnesia; the last deposit forms a colourless solution with rectified spirit, which, by gentle evaporation, gives up its emetia as a yellowish white pulverulent mass, which may be rendered perfectly white by redissolving it in alcohol, &c., as before. The process is rendered easier by first digesting the powdered ipecacuanha in ether.
b. (P. Cod.) Alcoholic extract of ipecacuanha, 1 part; water, 10 parts; dissolve, filter; add calcined magnesia, 1 part; evaporate to dryness, wash the product on a filter with very cold water, 5 parts; dry it again, and dissolve it in boiling alcohol; evaporate the filtered tincture to dryness, redissolve the residuum in a little water, acidulate (slightly) with dilute sulphuric acid, decolour with animal charcoal, filter, precipitate with liquor of ammonia, and dry the precipitate by a gentle heat.
c. (Ph. Suec. 1845.) Powdered ipecacuanha, 1 part; water, acidulated with sulphuric acid, 6 parts; digest, filter; add lime, 1 part, and evaporate to dryness over a water bath; the residuum is then exhausted with boiling rectified spirit, and otherwise treated as in the last formula.
Prop., &c. Pure emetia is white, pulverulent, inodorous, and bitter; fusible at 122° Fahr.; very soluble in alcohol and boiling water, but only slightly so in ether, oils, and cold water. It restores the blue colour of reddened litmus, and partially neutralises the acids, forming scarcely crystallisable salts. It is reddened by nitric acid, and this red colour is deepened by ammonia. Tincture of iodine produces a reddish precipitate in an alcoholic solution of emetia. With tincture of galls this solution behaves like morphia; but, unlike the last substance, the salts of iron produce no change of colour in it. These reactions, combined with its emetic properties, are sufficient for its identification.—Dose. White and pure emetia is emetic in doses of 1⁄20 to 1⁄16 gr. The large doses ordered in certain pharmaceutical compilations, evidently in error of the difference between the strengths of the pure and the impure or medicinal emetia, have, in several cases which have been reported on, produced very serious consequences.
The ‘Journal de Pharmacie et de Chemie,’ for September, 1875, contains a new process for the extraction of emetia, by M. A. Glenard. This process is based upon the combined use of lime and ether. It consists in treating with ether a suitably prepared powder, or an extract of ipecacuanha and lime, or the precipitate formed upon adding an excess of lime to a solution obtained by treating ipecacuanha in the cold with water acidulated by sulphuric acid. Either of these mixtures, or the precipitate, when treated with ether, will yield all the alkaloid it contains.
The alkaloid may be obtained from the ethereal solution by distilling it to dryness, and treating the residue with acidulated water, or by at once shaking the solution with acidulated water. A more or less acid aqueous liquid is thus obtained, which upon the addition of ammonia, yields the emetine almost colourless, and much more pure than that produced by the process ordinarily employed.
Preparation of Crystallised Hydrochlorate and Pure Emetine.—When water, acidulated with hydrochloric acid, is employed to remove the emetine from the ether, an acid solution is obtained, which, when sufficiently concentrated by evaporation, forms a nearly colourless, solid, crystalline mass. This mass is formed of extremely delicate needles, formed
in bundles that radiate around a central point, and form small spheres with an embossed surface, resembling mulberries in appearance. Upon pressing these crystals in a cloth the more or less coloured mother liquid runs off, and the crystals redissolved in water give a colourless solution, from which a fresh crystallisation of perfectly pure hydrochlorate of emetine can readily be obtained.
The production of this crystallised hydrochlorate of emetine is worthy of notice, since it does not accord with what has been stated by different authors, who have all considered emetine to be incapable of forming crystallisable salts. It is especially interesting in that it furnishes a convenient and certain method of obtaining perfectly pure emetine, for which it is only necessary to precipitate a solution of the hydrochlorate with an alkali. But it is important to observe that ammonia does not precipitate all the emetine of the hydrochlorate, and that the precipitate is less in proportion as the salt is more acid.
It might appear from this that emetine is soluble in hydrochlorate of ammonia. But the author finds that it is the result of a decomposing action exercised by the emetine upon the hydrochlorate of ammonia, as is shown by the following two experiments. If a little dry powdered emetine be placed in a glass containing a solution of hydrochlorate of ammonia, it may be observed to agglomerate and become transformed into a soft resinoid mass, at the same time the disengagement of ammonia may be recognised, and the resinoid mass gradually undergoes a kind of metamorphosis, and becomes white and crystalline. Again, if emetine in powder be suspended in water, and solution of hydrochlorate of ammonia be gradually added, the emetine is dissolved, and upon evaporation of the solution crystals of double hydrochlorate of emetine and ammonia is obtained.