_Wood Spirit._--Wood spirit, the pure form of which is methyl alcohol,
is one of the products of the destructive distillation of wood. The wood
is distilled in large iron retorts connected to apparatus for condensing
the distillation products. The heating is conducted slowly at first, so
that the maximum yield of the valuable products--wood acid (acetic acid)
and wood spirit--which distil at a low temperature, is obtained. When
the condensed products are allowed to settle, they separate into two
distinct layers, the lower one consisting of a thick, very dark tar,
whilst the upper one, much larger in quantity, is the crude wood acid
(containing also the wood spirit), and is reddish-yellow or
reddish-brown in colour. This crude wood acid is distilled, and the wood
spirit which distils off first is collected separately from the acetic
acid which afterwards comes over. The acid is used for the preparation
of alumina and iron mordants (see next lecture), or is neutralised with
lime, forming grey acetate of lime, from which, subsequently, pure
acetic acid or acetone is prepared. The crude wood spirit is mixed with
milk of lime, and after standing for several hours is distilled in a
rectifying still. The distillate is diluted with water, run off from any
oily impurities which are separated, and re-distilled once or twice
after treatment with quicklime.

_Stiffening and Proofing Process._--Before proceeding to discuss the
stiffening and proofing of hat forms or "bodies," it will be well to
point out that it was in thoroughly grasping the importance of a
rational and scientific method of carrying out this process that
Continental hat manufacturers had been able to steal a march upon their
English rivals in competition as to a special kind of hat which sold
well on the Continent. There are, or ought to be, three aims in the
process of proofing and stiffening, all the three being of equal
importance. These are: first, to waterproof the hat-forms; second, to