CAFFEINE 395 



inary practice have been almost as favorable ; over half the 

 cases have recovered when subjected to this medication. 

 Medication has, however, usually very little influence in 

 tetanus. Eecovery appears to be largely a matter of chance, 

 even with antitoxin. Cannabis Indica is occasionally em- 

 ployed as a sedative for irritable cough, and to relieve the 

 spasms of chorea. 



Caffeina. Caffeine. CsH^oN^O, + H^O. 



m. js. & B. p.) 



fi'z/mora^/m.— Theine,guaranine,E.; coffein.G.; cafe'ine.Fr. 



A feebly basic, proximate principle, obtained from the 

 dried leaves of Thea sinensis Linne (nat. ord. ternstrcemia- 

 cese), or from the dried seeds of Coffea arabica Linn6 (nat. 

 ord. rubiaoese), and found also in other plants. 



Habitat. — Indigenous to Africa, and cultivated in othei 

 tropical countries. 



Derivation. — Crushed coffee is treated with successive 

 portions of boiling water, and the resulting solution is 

 precipitated with lead acetate and filtered. Hydrogen sul- 

 phide decomposes the excess of lead acetate remaining in 

 the filtrate. The latter is then concentrated by evaporation 

 and neutralized with ammonia water. Caffeine crystallizes 

 on cooling.- The alkaloid is purified by charcoal and recrys- 

 tallization. 



Properties. — Fleecy masses of long, flexible, white crys- 

 tals, possessing a silky lustre, without odor, having a bitter 

 taste, and permanent in the air. Soluble in 80 parts of 

 water, 33 parts of alcohol, 555 parts- of -ether, or 7 parts of 

 chloroform. Also soluble in about 2 parts of boiling water, 

 and very soluble in boiling alcohol. Caffeine is neutral to 

 litmus paper. Caffeine exists, curiously enough, as the 

 active principle of the national non-alcoholic beverages in 

 use all over the world. Coffee contains .6-2.2 per cent, of 

 caffeine, together with glucose, fat, vegetable casein, tannic 

 acid, and an empyreumatic oil developed by roasting, i. e.. 



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