136 CHOLIN. NEUKIN. 



prepared from the yolk of egg. 1 The process is elaborate but 

 consists roughly in decomposing the residue of the yolk, left after 

 complete extraction with alcohol and ether, by boiling it for at 

 least an hour with caustic baryta. At the end of this period the 

 barium is precipitated by a stream of carbonic acid, the filtrate is 

 concentrated, extracted with absolute alcohol, and from this solu- 

 tion the cholin is precipitated as a salt by the addition of 

 platinum chloride. It is finally separated from this salt by means 

 of sulphuretted hydrogen. 



Wurtz a has obtained it synthetically, first by the action of gl ycol 

 CH 2 . OH 



chlorhydrin on trimethylamine, and then by that of ethylene 

 CH 2 .C1 

 oxide on a concentrated aqueous solution of trimethylamine. 



Cholin when pure is an oily liquid with a strong alkaline re- 

 action soluble in alcohol or ether. It yields crystalline com- 

 pounds with acids and some salts of which the double salts formed 

 with hydrochloric acid and the chlorides of either gold or platinum 

 crystallise readily and are employed for the detection and separa- 

 tion of the base. The platinum salt is readily soluble in water, 

 insoluble in alcohol. The gold salt is but slightly soluble in cold 

 water, but soluble in hot alcohol. 



When boiled in concentrated solution cholin is decomposed into 

 glycol and trimethylamine. 



(CH 3 ) 3 = N = C 2 H 4 (OH) 2 + N (CH.),. 



X CH 2 . CH 2 (OH) 



By oxidation with concentrated nitric acid it yields the ex- 

 tremely poisonous alkaloid muscarin C 5 Hi 5 NO 3 . 3 Cholin is itself 

 possessed of poisonous properties, and arising as it does from the 

 decomposition of lecithin and protagon is now recognised as one 

 of the alkaloidal products or ptomaines (see below) which occur 

 in putrefying animal tissues. 4 



r / OH i 



Neurin. C 5 H 13 XO. (CH 3 ) 3 = N \ CH _ CH , trimethylvinyl- 



ammonium hydroxide. 



This substance is closely related to cholin both in composition 

 and origin, but is much more powerfully toxic than that body. 



1 Diakonow, for ref. and details see Hoppe-Seyler's Hdbch. d. phi/s.-path. chem. 

 Anal. 1883, S. 163. 



2 Ann. d. Chem. u. Pharm. Supl.-Bd. vi. Sn. 116, 201. Cf. Baever, Ibid. Bd. 

 CXL. (1866), S. 306. 



3 Schmiedeberg u. Harnack, Arch. f. exp. Path. u. Pharm. Bd. vi. (1876), S. 101. 

 Cf. Berlinerblau, Ber. d. d. chem. Gesell. Jahrg. xvn. (1884), S. 1139. But see 

 also Bohm, Arch.f. exp. Path. u. Pharm. Bd. xix. (1885), S. 87. 



4 Brieger, Zt. ' f. klin. Jfed. Bd. x. (1885), S. 268. See also Brieger's works 

 referred to below, sub Ptomaines. 



