LECITHINS. 237 



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, which contains 

 3 molecules of lecithin and 4 molecules of cadmium chloride (ULPIANI 3 ) 

 is difficultly soluble in alcohol, but dissolves in a mixture of carbon 

 disulphide and ether or alcohol. The molybdenum compound must also 

 be mentioned (EHRENFELD 4 ) . A solution of lecithin in alcohol is not 

 precipitated by lead acetate and ammonia. 



Lecithins are easily carried down during the precipitation of other 

 compounds such as the protein bodies, and may therefore very greatly 

 change the solubilities 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 chap- 

 ter, and attention is there called to the necessity for more thorough inves- 

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

 sugar (BiNG) is also desirable, as we know nothing positive as to its nature. 

 According to the investigations of WINTERSTEIN, HIESTAND and E. 

 ScHULZE, 5 lecithins (phosphatides) containing carbohydrates occur in 

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

 are still not decided whether we are here dealing with combinations or 

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

 phosphatides as observed by GLiKiN. 6 



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 Chem. Centralbl., 1901, 2, p. 30 and 193. 



4 Zeitschr. f. physiol. Chem., 56. 



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

 52 and 55. 



6 Ber. d. d. chem. Gesellsch., 41. 



