CHEMISTRY OF THE PTOMAINES. 239 



base in the seed of the vetch, and in peas with a base re- 

 sembling betaine. The two bases have also been found 

 together in Scopolia atropoides by Siebert. 



Choline may readily be prepared, after the method of 

 DiAKONOW, from the yelk of eggs. These are extracted 

 with ether, then with alcohol, and the extracts thus ob- 

 tained evaporated, when the resulting residues are boiled 

 with baryta for one hour. The filtrate, after the removal 

 of the barium by carbonic acid, is evaporated and the 

 residue is abstracted with absolute alcohol. The alcoholic 

 solution is now precipitated with platinum chloride. 

 Brieger (II., 55) has presented a method which is much 

 simpler in its details and obviates the use of the expen- 

 sive platinum chloride. The tissues rich in lecithin, as 

 yelk of egg, brain, etc., are heated with concentrated 

 hydrochloric acid for some hours on the water-bath. The 

 insoluble residue is filtered off, and the filtrate, after neu- 

 tralization of the excess of free acid with carbonate of 

 sodium, is evaporated. The residue is extracted with 

 alcoiiol, and the alcoholic solution is precipitated with 

 alcoholic mercuric chloride. The precipitate thus obtained 

 on recrystallization several times from a large quantity of 

 boiling water, yields the pure double salt of choline. 



If desirable, it can be made from pure lecithin, best pre- 

 i)ared according to Gilson's method. Yelk of eggs is 

 repeatedly shaken up with ether until the latter is colored 

 only a faint yellow ; the ether solution then distilled, the 

 residue taken up in petroleum ether and filtered. The . 

 filtrate, in a separatory funnel, is well shaken with 75 

 per cent, alcohol, and this is repeated several times with 

 fresh alcohol. The alcoholic extracts are combined, allowed 

 to stand for some time, then filtered and subjected to dis- 

 tillation to remove traces of petroleum ether. The solu- 

 tion is now set aside in a cool place for several days ; the 

 precipitate which forms consists of cholesterine, etc., and 

 a little lecithin. The alcoholic solution is filtered by de- 

 cantation, then decolored by boiling with bone-black ; 

 rapidly evaporated at 50-60° to a syrupy consistency. 

 This residue is extracted with ether, the solution filtered 



