introduce steam for heating into the double bottoms of the two boilers.
The water of condensation flows out through the tubes, u. The water for
cooling enters the coolers, F, J, and Z, through the cocks, n, and flows
out through the tubes, v.

The acetate, previously crushed, is placed in the boiler, A, and the
quantity of acid necessary to decompose it is added. The mass is
afterward mixed with care by means of the stirrer, and the distillation
may then proceed at once.

The vapors of acetic acid that are disengaged enter the boiler, C,
through the tube, d, and are kept hot by the steam. In the head, D, they
are separated into two portions, viz., into concentrated acetic acid,
which condenses by reason of its high boiling point, and into steam,
which distills and carries along but a very small amount of acetic acid.
This steam passes through the pipe, G, into the worm, H, condenses, and
afterward flows into the vessel, N.

[Illustration: APPARATUS FOR THE MANUFACTURE OF VINEGAR.]

The acetic acid that accumulates in the boiler, C, must be again
vaporized and treated until it no longer gives off any steam at all
through the pipe, G. The amount of cooling water admitted into the worm,
e, that traverses the head, D, is regulated according to the degree of
concentration it is desired to give the acid. As soon as the steam can
no longer be separated in the boiler, C, and temperature has reached 118
degrees, the anhydrous acetic acid is distilled through the tube, g, and
received in the cooler, K, wherein it condenses. When the contents of
the boiler, A, have been distilled to dryness, the tube, d, is closed
and the cock of the tube, c, is opened. After this, steam is injected