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PHOSPHATIDES. 230
quantities of compound esters of Iauric, myristic, and stearic acid-; with radicals
of the alcohols, lethal. CuH«.OH, methal, CmH».OH, and stethal, CuHit.OH.
Cetin is a snow-white mass shining like mother-of-pearl, crystallizing in plates,
brittle, fatty to the touch, and which has a varying melting-point of 30 to 50° C.,
depending upon its purity. Cetin is insoluble in water, hut dissolves easily
in cold ether or volatile and fatly oils. It dissolves in boiling alcohol, but crys-
tallizes on cooling. It is saponified with difficulty by a solution of caustic potash
in water, but with an alcoholic solution it saponifies readily, and the above-men-
tioned alcohols are set free.
CH3
Ethal or cetyl alcohol, Ci6 H310. = (CHj) H, which occurs in smaller quantities
CH..OH
in beeswax and was found by Ludwig and v. Zeyxek in the fat from dermoid
Cysts—though this is denied by Ameseder, 1
—forms white, transparent, odorless,
and tasteless crystals which are insoluble in water but dissolve easily in alcohol
and ether. Ethal melts at 4!ho° C.
Spermaceti-oil yields on saponification valeric acid, small amounts of solid
fatty acids, and PHY6ETOLEIC ACID. This acid, which has. like hypogffiic acid,
the composition CuH&Os, occurs also, as found by Ljubarsky, 2
in considerable
amounts in the fat of the seal. It forms colorless and odorless needle-shaped
crystals which easily dissolve in alcohol and ether and melt at 34° C.
Beeswax may be treated here as concluding the subject of fats. It con-
tains three chief constituents: (1) cerotic acid, CseHo-.Oi, 3
which occurs as cetyl
ether in Chinese wax and as free acid in ordinarv wax. It dissolves in boiling
alcohol and separates as crystals on cooling. The cooled alcoholic extract of
wax contains (2) ceroleix, which is probably a mixture of several bodies, and
(3) mvricix, which forms the chief constituent of that part of wax which is
insoluble in warm or cold alcohol. Myricin consists chiefly of palmitic-acid
ester of nielissyl (myricyl) alcohol, C3oH6 i.OH. This alcohol is a silky, shining,
crystalline body melting at So C. Dunham * has found camaubic acid, C^J^sO–
in a phosphatide from the ox kidney.
2. Phosphatides.
In close relaticn to the fats stands a group of esters containing
nitrogen, phosphoric acid and fatty acid radicals. The representative
of this group longest known is lecithin. This latter is an ester combina-
tion of a nitrogenous base, choline, with a fatty acid-glycerophosphoric
acid, and Thudichum 5
has shown that a large number of more or less
analogous bodies occur in the animal body, especially in the brain.
All of these bodies have received the name phosphatides.
Those phosphatides which contain only one phosphoric acid radical
in the molecule are called monophosphatides; those with two such radicals
diphosphatides. The monophosphatides may contain one, two or more
1
Ludwig and v. Zeynek, Zeitschr. f. physiol. Chem. 23; Ameseder, ibid., 52.
;
Journ. f. prakt. Chem. (N. F.), 57.
1
See Henriques, Ber. d. deutsch. chem. Gesellsch., 30, 1415.
4
Journ. of biol. Chem., 4.
s
J. L. W. Thudichum, Die chemische Konstitution des Gehirns des Menschen,
etc., Tubingen, 1901.
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