With this substance also, he, as well as Skraup, has made Cocaine synthetically by heating in a tube to 100° C., a mixture of benzoyl-ecgonine, iodide of methyl, and methyl alcohol; the excess of the two latter is driven off by heat and the Cocaine extracted as a syrupy hydriodate; from the salt is produced pure Cocaine, melting at 98° C. and answering all other tests. (Ber. D. Chem. Ges. 1885, 2264.) Dr. Merck has also made the synthesis from anhydrous ecgonine by combining it with benzoic acid and iodide of methyl.—_Ib._ 2952. As atropine can be saponified by the action of alkalies into tropic acid and tropine, and as Cocaine and atropine act on the eye as mydriatics, Dr. Einhorn has demonstrated their chemical relationship by converting anhydrous ecgonine into tropidine (the anhydride of tropine), from which it only differs in containing the carboxyl group in place of an atom of hydrogen. On combining Cocaine with benzoic acid, benzoyl-ecgonine appears to be formed—the aqueous solution of these is not precipitated by ammonia. Cocaine is prepared by treating powdered coca leaves with a solution of carbonate of sodium, drying the mixture and exhausting it with petroleum spirit. The latter, which dissolves the cocaine with very little colouring matter, is agitated with very dilute hydrochloric acid, the petroleum is decanted and the cocaine precipitated from the aqueous solution by adding carbonate of sodium again. The precipitate is separated by shaking with ether, which on evaporation yields crystals of almost pure Cocaine. Most of the Cocaine now used is manufactured in a crude form in Lima, and imported from Callao. It yields about 85 per cent. of pure alkaloid, and is recrystallized or converted into the hydrochlorate after its arrival in Europe. No coloration is produced by dissolving pure Cocaine or its hydrochlorate in cold concentrated sulphuric acid; with the salt, effervescence occurs, owing to hydrochloric acid gas being set free. Some samples give a faint evanescent yellow coloration, and others give a magenta tinge which gradually passes to a brownish yellow, and eventually the solution becomes almost colourless. If Cocaine or a salt be moistened with nitric acid, evaporated to dryness, and a drop of alcoholic caustic potash added, a characteristic peppermint odour is developed.—P.J. 1890, 162. Report on action of ecgonine, benzoyl-ecgonine, and cocamine.—Th. Gaz. Oct. 1889, 698. As pure Cocaine (the alkaloid) is soluble in fats and oils, and its salts are not, it should always be used when it has to be combined with fatty or oily substances, for use externally, _e.g._:— =Bougies of Cocaine.= ½ grain each or more, with cacao-butter. Are useful in painful affections of the urethra. =Ceratum Cocainæ.= 1 in 30 of petroleum cerate. Is useful in burns, scalds, urticaria, pruritus, &c. =Collodium Cocainæ.= 2 per cent. in flexible collodion. Allays the itching, and is a cure for inflamed chilblains.