A Manual of the Chemistry of the Carbon Compounds

THE CARBON COMPOUXVX. 258
metallic compounds, and very readily nudergoes decomposition by
boiling its alcoholic solution alone, or quicker in presence of alkalis
or acids, the produots being choline, glycerin-phosphoric acid, and
fatty adds (palmitic acid and oleic acid C,,Hl40i).
This decomposition, together with the chemical character of lecithine,
explain its constitution:—
i OH
10.0JT4((J
Lecithine is glycerin-phosphoric acid in which two atoms of
hydrogen in the bydroxyl-gi'oups of glycerin are replaced by the
radicals of oleic and palmitic acids, whilst cliolin, a compound being
at the same time an ammoi>iimi:base ami an nlcohol, forms with
glycerin-phosphoric acid an acid compound ether, Lecithine is
therefore at the same time a fat, a base, and an acid,
It appeara very probable that several lecitliines exist, containing
radicals of different fatty acids,
GLYCER1C ACID CjH0O4,
To prepare this acid, glycerine is diluted with au equal volume of
water aud poured on the top of strong nitric acid contained in a high
cylinder. The mixture, after standing for several days, is evaporated
on a water-bath, and the syrupy residue dissolved in water and
neutralized with lend oxide. The lead glycerate is purified by recrystallization,
and an aqueous solution of the pure salt decomposed
by hydrogen sulphide.
On evaporating the filtrate on a water-bath, glyceric acid remains
behind as a thick, syrupy, and very sour liquid.
On heating it is resolved into water and pyruvic acid (aee page 230);
when it is fused with caustic potash it is resolved into acetic acid and
formic acid.
By the action of phosphorus iodide and water it is rednced to fi
iodopropionic add.
$ Iodopropionie Acid C3H6IO3 founa white pearly crystals melting
at 82°. When its aqueous solution is heated with silver oxide,
hydraa