LECITHINS, 245 



resistant than was generally believed , and further investigations with 

 pure lecithin are desirable. 



With considerable water the lecithin gives an emulsion or colloidal 

 solution which is not only precipitated by salts with divalent cations, 

 Ca, Mg, and others as claimed by W. KOCH, but is also precipitated accord- 

 ing to LONG and F. GEPHART 1 by salts with monovalent cations, although 

 slowly. In putrefaction, lecithins yield glycerophosphoric acid and choline; 

 the latter further decomposes with the formation of methylamine, ammonia, 

 carbon dioxide, and marsh gas (HASEBROEK 2 ) . If dry lecithin be heated 

 it decomposes, takes fire, and burns, leaving a phosphorized ash. On 

 fusing with caustic alkali and saltpetre it yields alkali phosphates. 



Lecithins combine with acids and bases. The compound with hydro- 

 chloric acid gives with platinum chloride a double salt which is insoluble 

 in alcohol, soluble in ether, and which contains 10.2 per cent platinum 

 (for distearyl-lecithin) . The cadmium-chloride compound, whose com- 

 position has been found somewhat variable by different investigators 

 is soluble with difficulty in alcohol, but dissolves in a mixture of carbon 

 disulphide and ether or alcohol. A solution of lecithin in alcohol is not 

 precipitated by lead acetate and ammonia. 



Lecithins (and the same applies to the phosphatides in general) are 

 easily carried down during the precipitation of other compounds, such 

 as the protein bodies, and may therefore very greatly change the solubil- 

 ilities of other bodies. It is not known whether we are here dealing 

 with an adsorption or a chemical combination, and the conditions are 

 not the same in all cases. The combination with protein, the vitellines 

 and lecithalbumins have been discussed in a previous chapter, and 

 attention is there called to the necessity for more thorough investigation 

 of this subject. Further investigations of the so-called lecithin-sugar 

 (BING) is also desirable, as we know nothing definite as to its nature. 

 According to the investigations of WINTERSTEIN, HIESTAND and E. 

 SCHULZE, lecithins (phosphatides) containing carbohydrates occur in 

 the plant kingdom, and contain about 20 per cent carbohydrate. We 

 are still not decided whether we are here dealing with combinations 

 or admixtures. 3 The same is true for the iron content of the lecithins or 

 phosphatides as observed by 



1 W. Koch., Zeitschr. f. physiol. Chem., 37; Long and Gephart, Journ. of Amer. 

 Chem. Soc., 30; see also Forges and Neubauer, Biochem. Zeitschr., 7. 



2 Zeitschr. f. physiol. Chem., 12. 



3 Winterstein and Hiestand, Zeitschr. f. physiol. Chem., 47 and 54; Schulze, ibid., 

 52 and 55; V. Njegovan, ibid., 76. 



4 Ber. d. d. chem. Gesellsch., 41. 



