26 and 27), and the dish and bottle washed out with water and
about 50 cc. of methylated ether (using
small quantities at a time), into the sepa-
rator; the stopper is now put in, the con-
tents violently shaken up for about ten
minutes, and the mixture allowed to
separate; sometimes there is a little
difficulty in the separation, an emulsion
being formed. In such cases an addi-
tion of 2 or 3 cc. of absolute alcohol
with a rotatory motion puts matters
all right. When complete separation
is ensured, the aqueous solution is
tapped off into a second separator, the ^"'- ^^- ^'°- "'•

aqueous solution shaken up with 20 cc. more ether, allowed
to separate, the aqueous solution tapped off as before, and the
ethereal extract added to the main portion, which in turn is
washed three times with 20 cc. of water, and the washings
added to the main aqueous solution. The ethereal solution of
the mineral oil is now tapped off into a weighed flask attached
to a Liebig's condenser, and the ether distilled off; the residual
mineral oil is then dried in a water oven, air being pumped into
it occasionally to get rid of the last traces of water, which
was taken up by the ether ; after which it is cooled and
weighed, and dried again until no further loss occurs, If the
mineral oil present be light, and of low boiling point, consider-
able loss would be incurred by its evaporation by this process ;




196



OILS.
