Those which have been obtained from it are: the salicylate, oxalate, hydrobromide, sulphate, acetate, and finally the hydrochlorate, which forms an exception to the general rule, and is obtained more easily in the crystalline form than any other. The solutions of the salts of Cocaine are precipitated by the caustic alkalies, carbonate of sodium, carbonate of ammonium, the alkaline bicarbonates, the bichloride of mercury, the protochloride of tin, bichloride of platinum, and by ammonia, which, added in excess, redissolves the precipitate formed by it. Iodine water, iodized potassium iodide, and picric acid precipitate the solutions of salts of Cocaine. When Cocaine is heated to 100° in a sealed tube with concentrated hydrochloric acid, it separates into benzoic acid and a new base, for which M. Wœhler has proposed the name of _Ecgonine_. Lassen has discovered another nitrogenous base resulting from the separation of Cocaine—_hygrine_. _Preparation._—The process used by Niemann for obtaining Cocaine is as follows: This chemist digested Coca leaves, cut into very small pieces, in alcohol (at 55°), for several days, adding sulphuric acid. The tincture which resulted from this operation was separated by expression, filtered, and treated with slaked lime. The liquid, which was primarily of a greenish-brown, was both divested of a part of its chlorophyll and also of a certain waxy substance. Niemann then neutralized this with sulphuric acid and evaporated it over a water-bath. The residue was then treated with water, which caused the separation of the rest of the chlorophyll and of the sulphate of Cocaine that it contained, and which was precipitated by means of the carbonate of sodium. He separated it finally with ether and purified it by several re-crystallizations in alcohol. This process was modified by Lassen, who precipitated the aqueous solution with the subacetate of lead. In this way he was able to obtain about six grammes of Cocaine from a kilogramme of Coca leaves. Moreno y Maïz proposed a third process. He mixed intimately, slaked lime with finely-pulverized Coca leaves, letting the mixture stand for nearly twenty-four hours, in order that the lime might react suitably on the alkaloid, imitating in that, the Indian who mixes with his quid the _llipta_, of which we have already spoken. He afterward lixiviates it with alcohol at 40°. II.—PHYSICAL STUDY. We have reviewed the works of the different authors who occupied themselves with Coca; their various labors, although very interesting, did not reach the famous discovery of local anæsthesia, and it is to Köller, of Vienna[10], that the honor belongs of having brought to light the remarkable effect of Cocaine when applied to the conjunctival membrane. This soon awakened general curiosity. From all quarters came works on the subject. Reuss, Kœnigstein, Jellinck, Schrotter, Knapp and others hastened to give to the profession the result of their researches.