VI. THE WATERY FLUID IS NOW AGAIN SHAKEN UP WITH PETROLEUM ETHER,

in order to take up the rest of the chloroform, and the watery fluid is saturated with ammonia. The watery solution of aconitine and emetine is liable to undergo, through free ammonia, a partial decomposition; but, on the other hand, it is quite possible to obtain, with very small mixtures of the substances, satisfactory reactions, even out of ammoniacal solutions.

VII. THE AMMONIACAL WATERY FLUID WITH PETROLEUM ETHER.

In the earlier stages Dragendorff advises the shaking up with petroleum ether at about 40°, and the removal of the ether as quickly as possible whilst warm. This is with the intention of separating by this fluid strychnine, brucine, emetine, quinine, veratrine, &c. Finding, however, that a full extraction by petroleum ether is either difficult or not practicable, he prefers, as we have seen, to conclude the operation by other agents, coming back again upon the ether for certain special cases. Such are the volatile alkaloids; and here he recommends treatment of the fluid by cold petroleum ether, taking care not to hasten the removal of the latter. Strychnine and other fixed alkaloids are then only taken up in small quantities, and the greater portion remains for the later treatment of the watery fluid by benzene.

A portion of the petroleum ether, supposed to contain in solution volatile alkaloids, is evaporated in two watch-glasses; to the one, strong hydrochloric acid is added, the other being evaporated without this agent. On the evaporation of the petroleum ether, it is seen whether the first portion is crystalline or amorphous, or whether the second leaves behind a strongly-smelling fluid mass, which denotes a volatile alkaloid. If the residue in both glasses is without odour and fixed, the absence of volatile acids and the presence of fixed alkaloids, strychnine, emetine, veratrine, &c., are indicated.

THE PETROLEUM ETHER RESIDUE FROM AMMONIACAL SOLUTION.

1. It is fixed and Crystalline.2. It is fixed and Amorphous.3. It is fixed and Odorous.
A. The crystals are volatilised with difficulty. A. On adding to the watch-glass a little hydrochloric acid, crystals are left behind.
aa. Sulphuric acid dissolves it without colour. aa. Its solution is not precipitated by platin chloride.
α. Potassic chromate colours this solution a transitory blue, then red.α. The purest sulphuric acid dissolves it almost without colour; sulphuric acid containing nitric acid, red quickly becoming orange.α. The crystals of the hydrochloric compound act on polarised light; and are mostly needle-shaped and columnar.
Strychnine.Brucine.Coniine and Methyl-Coniine.
β. Potassic chromate does not colour it blue; with chlorine water and ammonia it gives a green colour.β. Sulphuric acid dissolves it yellow, becoming deep red.β. The crystals are cubical or tetrahedral.
Quinine.Veratrine.Alkaloid from Capsicum.
γ. Sulphuric acid dissolves it brown-green; Fröhde’s reagent red, changing into green.
Emetine.
bb. The solution of the hydrochlorate of the alkaloid is precipitated by platin chloride.
Sarracinin.
γ. Sulphuric acid dissolves it yellow, and the solution becomes gradually a beautiful deep red. B. The residue of the hydrochlorate of the alkaloid is amorphous, or, by further additions of HCl, becomes crystalline.
Sabadilline.
δ. The crystals are easily volatilised.
Coniine.
aa. Its diluted aqueous solution is precipitated by platin chloride.
α. The hydrochlorate salt, being quickly treated with Fröhde’s reagent, gives after about two minutes a violet solution which gradually fades.
Lobeliin.
β. The hydrochlorate smells like nicotine, and becomes by Fröhde’s reagent yellow, and after twenty-four hours pale red.
Nicotine.
γ. The hydrochlorate is without odour, the free base smells faintly like aniline.
Sparteine.
bb. The substance is not precipitated from a diluted solution by platin chloride.
α. Its petroleum ether solution produces no turbidity with a solution of picric acid in petroleum ether; but it leaves behind, when mixed with the above, crystals mostly of three-sided plates.
Trimethylamine.
β. The petroleum ether solution gives, on evaporation, when treated similarly, moss-like crystals. The substance is made blue by chloride of lime, as well as by diluted sulphuric acid and bichromate of potash.
Aniline.
γ. The alkaloid does not smell like methylamine, and is not coloured by chloride of lime, sulphuric acid, or chromate of potash.
Volatile alkaloid of the Pimento.

VIII. THE AMMONIACAL SOLUTION IS SHAKEN UP WITH BENZENE.

In most cases petroleum ether, benzene, and chloroform are more easily separated from acid watery fluids than from ammoniacal, benzene and chloroform causing here a difficulty which has perhaps deterred many from using this method. Dragendorff, however, maintains that he has never examined a fluid in which he could not obtain a complete separation of the benzene and water. If the upper benzene layer is fully gelatinous and emulsive, the under layer of water is to be removed with a pipette as far as possible, and the benzene with a few drops of absolute alcohol and filtration. As a rule, the water goes through first alone, and by the time the greater part has run through, the jelly in the filter, by dint of stirring, has become separated from the benzene, and, finally, the jelly shrinks up to a minimum, and the clear benzene filters off. Dragendorff filters mostly into a burette, from which ultimately the benzene and the water are separated.

The principal alkaloids which are dissolved in benzene are—strychnine, methyl and ethyl strychnine, brucine, emetine, quinine, cinchonine, atropine, hyoscyamine, physostigmine, aconitine, nepalin, the alkaloid of the Aconitum lycoctonum, aconellin, napellin, delphinine, veratrine, sabatrin, sabadilline, codeine, thebaine, and narcotine.