This consists of a flask B of
about 75 c.c. capacity, which has a glass tap fused on, with two
capillary tubes attached, the one passing upward, the other downward.
The neck of flask B is ground into the neck of flask A, which holds
about 90 c.c. Either of the flasks can be placed in communication with
the external air by the opening _a_. The ether must be previously
washed with one or two tenths of its volume of water, to remove traces
of alcohol. The operation is performed as follows: 10 c.c. of well
mixed milk are weighed in (or measured into) flask A, 10 c.c. of
hydrochloric acid added, and the mixture heated to boiling on an
asbestos sheet. The boiling must not exceed a minute and a half, the
fluid being shaken from time to time, and not allowed to become of a
deeper color than a dark brown [not black]. The flask is cooled, and
25 c.c. of ether added. The two flasks are connected as shown in the
figure, the tap closed, and the whole shaken for a few minutes, the
flask being vented two or three times by the opening _a_.
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