This now important alkaloid, obtained from Coca, was first isolated by Niemann in 1860. From analysis he gave it the formula of C₃₂H₂₀NO₈ (old notation), but Lossen in 1862 assigned it the now accepted formula of C₁₇H₂₁NO₄₁ (new notation). It crystallizes in shining monoclinic prisms, and requires 700 or more parts of water to dissolve it; according to Dr. Paul, it takes upwards of 1,300 parts; it dissolves more readily in hot water, but rapidly undergoes decomposition, forming an acid solution which contains benzoyl-ecgonine, ecgonine, and benzoate of cocaine, which do not separate upon cooling. It is also soluble in alcohol (about 1 in 20), freely so in chloroform, ether (about 1 in 3), oil of cloves, and many other volatile oils, and 1 in 10 respectively of melted vaseline, castor oil, and other fixed oils. The latter solutions have proved serviceable in eye cases. The following are also ready solvents, each taking up about 1 of it in 3 parts: benzol, toluol, and amylic alcohol; of petroleum spirit about 25 parts are required, much less if hot; from this solution, also from hot alcohol, wood spirit, acetone and chloroform it readily crystallizes on cooling. It is almost tasteless, but produces a tingling numbness on the tongue, and local anæsthetic action on all mucous membrane. Good Coca leaves yield 0.5 per cent. or more of Cocaine, but the average is less—if fermented, often _nil_. Cocaine seems to be very sensitive to chemical and physical action, and readily yields derivatives. In working the dried leaves the following compounds are also met with, Hygrine (a volatile alkaloid), Benzoyl-Ecgonine and Ecgonine, Cocamine and Cocaidine, accompanied by Coca-tannin and Coca-wax. All the Coca alkaloids, according to Hesse,[30] are derived from ecgonine methyl ester, and the ecgonine itself from pyridine. Cocaine is the most important, whilst the others, so far as is known, do not appear to be distinctly noxious, but at the same time they are inferior to Cocaine in anæsthetic properties. Ecgonine (together with benzoic acid and methyl alcohol) may also be obtained as a derivative from Cocaine when the latter is heated with hydrochloric acid, thus:— C₁₇H₂₁NO₄ + 2H₂O = C₉H₁₅NO₃ + C₇H₆O₂ + CH₄O Cocaine. Water. Ecgonine. Benzoic Methyl Acid. Alcohol. [Footnote 30: A Study of Coca Leaves and their Alkaloids:—P.J. 1891, 1109, 1129, 101.] Dr. W. Merck, by operation with hydrochloric acid on benzoyl-ecgonine, a by-product obtained in the manufacture of, and probably a derivative from Cocaine, converted this into benzoic acid and ecgonine, thus:— C₁₆H₂₁NO₄ = C₉H₁₅NO₃ + C₇H₆O₂ Benzoyl- Ecgonine. Benzoic Acid. Ecgonine.