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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. Gephart1
by salts with monovalent cations, although
slowly. In putrefaction, lecithins yield dvcerophosphoric acid and choline;
the latter further decomposes with the formation of methylamine, ammonia,
carbon dioxide, and marsh gas (Hasebiioek 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
(Bixg) 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 Glikin.4
1
W. Koch., Zeitschr. f. physiol. Chem., 37; Long and Gephart, Journ. of Amer.
Chem. Soc, 30; see also Porges and Neubauer, Biochem. Zeitschr., 7.
- Zeitschr. f. physiol. Chem., 12.
3
Winterstein and Hiestand, Zeitschr. f. physiol. Chem., 47 and 54; Schulze, ibid. t
52 and 55; V. Xjegovan, ibid., 76.
4
Ber. d. d. chem. Gesellsch., 41.
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