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422 THE LIVER.
ether, benzene, and acetone. Taurocholic acid is very soluble in water,
and the solution has a very sweet taste, with only a slight bitter taste.
It can hold the difficultly soluble glycocholic acid in solution. This is
the reason why a mixture of glycocholate with a sufficient quantity of
taurocholate, which often occurs in ox-bile, is not precipitated by a dilute
acid. Its salts are, as a rule, readily soluble in water, and the solutions
of the alkali salts are not precipitated by copper sulphate, silver nitrate
or lead acetate. Basic lead acetate gives, on the contrary, a precipitate
which is soluble in boiling alcohol. The alkali salts are not only pre-
cipitated from their solution by the same neutral salts that precipitate
glycocholic acid, but also by potassium chloride, and by sodium and
potassium acetates.
Taurocholeic Acid is a second taurocholic acid, detected by Hammar-
sten in dog-bile and isolated by Gullbring 1
from ox-bile, and has the
formula C26H45NSO6 or C27H47NS06- Thus far it has been obtained
only in the amorphous form. It is readily soluble in water, and has a
disagreeably bitter taste. It is also readily soluble in alcohol, but insoluble
in ether, acetone, chloroform, and benzene. The alkali salt, soluble in
water, can be salted out by NaCl as a pasty mass. The solutions of the
salts can be precipitated by ferric chloride. The cleavage products are
taurine and choleic acid.
The taurocholic acids are most simply prepared from bile, free from
plycocholic acid or poor therein, such as fish- or dog-bile, easiest from the
latter. The aqueous solution of the mucus-free bile is almost completely
precipitated by ferric chloride. The precipitate is worked for tauro-
choleic acid and the filtrate for taurocholic acid. The iron is first removed
from the filtrate by Na2COs, and then the faintly alkaline filtrate satu-
rated with Nad. The taurocholate separates out and after further
purification is decomposed by alcohol containing hydrochloric acid. The
taurocholic acid is precipitated from the alcoholic filtrate by ether and
recrystallized from alcohol containing water by the addition of ether.
The taurocholeic acid is obtained from the above iron precipitate by treat-
ing it with soda, and decomposing the alkali salt of the taurocholeic acid
with alcohol, containing HC1, and precipitating the acid from the alcoholic
solution with ether and repeating this precipitation from alcohol by ether.
Cheno-taurocholic Acid. This is the most essential acid of goose-bile and has
the formula GaEUNSOe. This acid, but little studied, is amorphous and solu-
ble in water and alcohol.
The taurocholic acids differ from the glycocholic acids in being
readily soluble in water. In the bile of the walrus, on the contrary, a
relatively insoluble, readily crystallizable taurocholic acid occurs, which
Hammarsten, Zeitschr. f. physiol. Chem., 43; Gullbring, ibid., 45.
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