432 LECITHIN. [BOOK i. 



ultimate analysis (C = 64*27 p.c. ; II = 1 1/4 ; N = 1/8 ; P = 3'8) is 

 C 4f E 90 NP0 9 + H 2 O. When decomposed it yields glycerin-phosphoric 

 acid, stearic acid and neurine the very same products which Liebreich 

 had obtained from protagon. 



Compounds Lecithin forms compounds both with bases and 



of lecithin. acids, as for example with potassium and hydrochloric 



acid, and the latter forms a platinum compound 



(Strecker) ; in the case of distearyl-lecithin (see ' constitution of 



lecithin ') this compound would have the formula 



A similar compound with cadmium chloride exists. The platinum 

 compound is soluble in ether, but it may be precipitated from the 

 ethereal solution by an excess of alcohol. 



Diaconow's Diaconow had in the meantime directed his investi- 



assertion of gation to the brain, and one month after the publication 

 the presence of his first paper there appeared a second 1 which has 

 of lecithin in exerted a most weighty influence, causing physiological 

 chemists to come to the conclusion that Liebreich's 

 protagon does not exist as a definite proximate principle, but that 

 it consists of a mixture of lecithin with a body free from phosphorus, 

 cerebrin. 



Diaconow's Brain freed from its membranes and from blood, is 



method of finely divided and repeatedly extracted with ether ; 



separating the residual mass is digested with absolute alcohol 

 lecithin from a t 40 C., and the alcoholic solution thus obtained is 



ain ' cooled to ; the precipitate which separates is filtered 



off, and washed with a little cold absolute alcohol and afterwards 

 once again with ether. A portion of the substance dissolves in ether, 

 whilst another, protagon, remains as a residue. The latter is 

 repeatedly extracted with ether at ordinary temperatures, and the 

 collected ethereal extracts are subjected to distillation ; the residue 

 is dried at 40, dissolved in a little absolute alcohol, and the alcoholic 

 solution is cooled. There separates a white substance having the 

 composition and properties of lecithin. The substance is amorphous, 

 non-pulverizable, hygroscopic, swells in water and when shaken with 

 it forms an emulsion. When burned it leaves as a residue phosphoric 

 anhydride (?). When decomposed with lime- or baryta-water it 

 yields in addition to neurine, barium stearate and glycerin-phos- 

 phate. 



Analyses of the body separated in this way by Diaconow furnished 

 the following results. 



1 Diaconow, "Das Lecithin im Gehirn.'' Centralblatt filr die medicinischen Wissen- 

 schaften, No. 7, 8th Feb. 1868, p. 97. 



