APPENDIX TO CHAPTER IV CHOLINE 153 



porated with a drop of a saturated alloxan solution, a reddish violet 

 colour results, which becomes more blue on the addition of caustic 

 soda. The reaction is not characteristic and similar colorations are 

 produced by ammonium salts, proteins and amino-acids (cf. Hurtley 

 and Wootton, Journ. Chem. Soc., 1911, 99, 288). 



Choline, as free base, deliquesces in the air and absorbs carbon 

 dioxide. According to Gulewitsch aqueous solutions may be con- 

 centrated by boiling to 4 per cent, concentration, when trimethylamine 

 is given off. The base is not changed rapidly by boiling with alkalies 

 in dilute solution ; on keeping for a long time in aqueous solution 

 neurine is formed. Concentrated nitric acid converts it to its nitrous 

 acid ester, pseudo-muscarine (cf. addendum, p. 68). It may be 

 oxidised to betaine (" Oxyneurin," Liebreich [1869, i]). 



The organisms from a hay infusion probably to some extent con- 

 vert choline into neurine (Schmidt [1891]). Brieger had already 

 surmised that this change takes place in putrefaction and found that all 

 the choline disappeared within the first week, but Gulewitsch [1864, 

 Ch. I] isolated choline from putrid horse meat after four months' putre- 

 faction at 15. According to Ackermann and Schutze [1910, 1911, 

 Ch. I] Bacterium prodigiosum forms trimethylamine and a little mono- 

 methylamine from choline, but Bacillus vulgatus does not decompose it. 

 Prolonged anaerobic putrefaction yields CO 2 , CH 4 , N 2 , NH 3 and 

 CH 3 NH 2 (Hasebroek [1887, Ch. I]). 



All known choline salts are readily soluble in water, except the 

 periodide, the phosphotungstate and the double salts with gold and 

 with mercury. Some, as for instance the chloride C 5 H 14 ONC1, are 

 deliquescent. The chloride also dissolves readily in absolute alcohol 

 (distinction from betaine). 



The sulphate (C 5 H U ON) 2 SO 4 , the acetate C 5 H U ON . C 2 H 3 O 2 , and the 

 monophosphate C 5 H U ON . H 2 PO 4 are all readily soluble in water, and 

 crystallise in needles. The first two are readily soluble in alcohol, but 

 the phosphate is not. The acetate is deliquescent (Renshaw [1910]). 



The perchlorate C 5 H 14 ON . C1O 4 , m.p. 273, dissolves in 2-9 parts of 

 water at 1 5 and is not birefringent. The perchlorate of the nitric acid 

 ester of choline is, however, only very slightly soluble (0*62 parts in 100 

 parts of water at 1 5). It is obtained by evaporating O'l grm. of choline 

 perchlorate in 50 c.c. of water with 2 c.c. of 65 per cent, nitric acid, 

 dissolving the residue in a little water and adding a few drops of a 

 concentrated aqueous solution of perchloric acid. This latter salt is 

 characteristic; it is strongly birefringent, melts at 185-186 and is 

 suitable for the isolation of choline (Hofmann and Hobold [1911]). 



