NEUBIN. 289 



Formula No. 3 was the one accepted by Liebreich for neurin, but, 

 according to Baeyer, Liebreioh's neurin salt was not simple but a 

 mixture of Nos. 1 and 2. He himself accepted formula No. 1 as 

 the platinochlorid of neurin, and distinctly states (Annal. d. Chem. 

 u. Pharm., 142, 323, 1867) that neurin is in composition trimethyl 

 oxyethyl-ammonium hydroxid. And according to him, cholin from 

 bile and sinkalin from white mustard appear to be identical with 

 neurin. 



This nomenclature of Baeyer's was at first adopted by Wurtz 

 and others, who showed that the oxyethyl base was identical with 

 cholin and sinkalin. On that account Strecker, in 1868 (Annal., 

 148, 79), suggested the restriction of the name cholin to the oxy- 

 ethyl base, and to reserve the name neurin for the base whose platin- 

 ochlorid is represented in No. 3, as originally was done by Lieb- 

 reich. In 1869 Liebreich showed that pure protagon, when heated 

 with baryta for twenty-four hours, yields a substance having the 

 composition of the vinyl base : 



kU' 



)H = CH, 

 (OH. 



The platinochlorid of this base crystallized in five-sided yellow 

 plates, which after a time, on exposure to the air, became cloudy ; 

 on treatment now with water a portion dissolved and the solution 

 was found to contain the oxyethyl base. Furthermore, he observed 

 that when the alcoholic extract of the brain, from which all the pro- 

 tagon had been removed, is treated with baryta, only the latter, the 

 oxyethyl base, is obtained. Finally, in 1870, Wurtz abandoned the 

 use of the term neurin to designate the oxyethyl base, and returned 

 to the name cholin, originally applied to the oxyethyl base by its 

 discoverer, Strecker. Nevertheless, the confusion in the use of these 

 two terms continued to exist even until very recent years, causing no 

 little misunderstanding. Thus, Marino-Zuco (1885), in his excel- 

 lent researches on the genesis of ptomains, applies the term neurin, 

 following Baeyer's precedent, to the oxyethyl base, C^Hj^NO^ , which 

 is really cholin, according to the proper nomenclature. 



We have gone somewhat at this point in detail into the history 

 and proper use of the terms neurin and cholin because of the confu- 

 sion which is sure to arise if the distinction is not thoroughly borne 

 in mind. The name neurin, then, should be used only to denote the 

 vinyl base CjHjjNO. It is trimethyl-vinyl-ammonium hydrate. 

 On the other hand, cholin is the oxyethyl base CgHj^NOj , which is 

 trimethyl-oxyethyl-ammonium hydrate. 



Neurin has been obtained by Brieger (1883) in the putrefaction of 



horse, beef and human flesh for five or six days in summer. It also 



occurs in the commercial, so-called " neurin," together with cholin 



(Brieger, I., 34) ; in commercial 25 per cent, cholin (Schmidt). 



19 



