and the mixture is allowed to stand for forty-eight hours or longer
at room temperature (20-25'0).

The solid is then filtered off, washed first with water, then with 400 cc.
of 10 per cent acetic acid (to remove the dimethylaniline) and finally
with distilled water. The last filtrate is generally pale pink.
The solid is sucked as dry as possible, spread out on a tray in order
to allow most of the water to evaporate (fifteen to twenty hours)
and then suspended in 4 l. of methyl alcohol in a 12-l. flask.
This mixture is stirred on the steam bath under a reflux condenser
for one to two hours, allowed to cool slowly, and then chilled in an ice
bath and filtered. The solid product is washed with a second 4 l.
of cold methyl alcohol. After being dried in air, the product
varies in weight from 820 to 870 g.

The product is extracted with boiling toluene in the following manner:
150 g. are placed in a fluted filter paper of 29 cm.
diameter in a 25-cm. glass funnel which passes through the cork
of a 2-l. flat-bottom conical flask containing 1250 cc.
of toluene (Fig. 2). The flask is heated on an electric stove,
and a 12-l. round-bottom flask is placed on the funnel to act
as a condenser, cold water being run through the flask.
The toluene is boiled until the condensed liquid runs through
almost colorless (this requires from four to ten hours). The heating
is then discontinued, and, as soon as the liquid ceases to boil,
the flask is removed to a bath containing water at 90-100'0;
the level of the water should be slightly above the level
of the liquid in the flask. This arrangement permits the
temperature to fall slowly so that large crystals are obtained.
In the meantime a second conical flask containing 1250 cc.