CHEMISTRY OF THE PTOMAINES. 235 



the methods of extractiou, aud, indeed, he claimed to have 

 converted choline platinochloride, by heating witli hydro- 

 chloric acid, into neurine. This statement has been dis- 

 puted by Brieger, who showed that the platinochloride 

 of choline, as well as the hydrochloride, may be heated 

 with fifteen or thirty per cent., or even concentrated hydro- 

 chloric acid, for six to eight hours on a water-bath, with- 

 out any conversion whatever (III., 15). That neurine 

 may be obtained from choline, at least by chemical pro- 

 cesses, was shown by Baeyer, in 1866, who found that 

 choline chloride, when heated with several times its volume 

 of concentrated hydriodic acid and some red phosphorus, 

 gave a compound CgHijNIj which, on digestion with fresh, 

 moist silver oxide, yielded a vinyl base identical with that 

 previously obtained synthetically by Hofmann, and now 

 known as neurine. Brieger has tried, unsuccessfully, to 

 bring about this dehydration by the putrefaction of pure 

 choline (I., 59). However, Schmidt and Weiss (1887) 

 were more successful, and they found that choline, as well 

 as the hydrochloride and lactate, is changed by the action 

 of microorganisms into the strongly poisonous neurine. 

 Their results are given in full under choline (see page 244.) 

 From what has been said it is evident that neurine can 

 only arise from choline, and this, as will be seen later, is 

 derived from lecithin. 



Neurine is almost invariably accompanied by choline, 

 from which, however, it can be readily separated by the 

 difference in the solubilities of the platinochlorides. It 

 occurs in the mercuric chloride precipitate (and in the 

 filtrate), and from this it can be obtained, after removal of 

 the mercury, by precipitating the solution of the mixed 

 hydrochlorides in absolute alcohol by platinum chloride. 

 The platinochlorides are then separated by recrystallization 

 from water, since the neurine is difficultly soluble, while 

 the choline salt is readily soluble. 



The free base pos.sesses a strong alkaline reaction, and 

 on contact with the fumes of hydrochloric acid it yields a 

 cloud. According to Liebreich, the alkaline solution 

 cannot be neutralized by passing through it carbonic acid. 



