rying may take place rapidly. Curtains
of canvas are hung all around the lumber on the same principle
that windows in newly plastered buildings are hung with muslin.
The moisture is absorbed on the inner surface of the curtain and
evaporates from the outer surface. Improvements in kiln-drying are
along the line of moist air operation. In common practice, however,
the moist air principle is often neglected.

There are two methods in operation, the progressive method and the
charge method. In the progressive, the process is continuous, the
loads going in at one end of the kiln, and out at the other, the
temperature and the moisture being so distributed in the kiln, that
in passing from the green to the dry end, a load of lumber is first
moistened, then heated, and finally dried out. In the charge system,
the process is intermittent, one charge being removed before a new one
is admitted. This gives the best results with high grade lumber for
special uses.

A modification of hot-air-seasoning is that which subjects the wood to
a moderate heat in a moist atmosphere charged with the products of the
combustion of fuel.

(3) Small pieces of wood may be effectively seasoned by being boiled
in water and then dried. The process seems to consist of dissolving
out albuminous substances and thus allowing freer evaporation. Its
effect is probably weakening.

(4) Soaking in water is sometimes used as a good preparation for
air-seasoning. Previous soaking hastens seasoning. River men insist
that timber is improved by rafting. It is a common practice to let
cypress logs soak in the swamps where they grow for several months
before they are "mined out." They are eagerly sought after by joiners
and carpenters, because their tendency to warp is lessened. Ebony is
water-soaked in the island of Mauritius as soon as cut. Salt water
renders wood harder, heavier, and more durable and is sometimes
applied to ship timbers, but cannot be used with timbers intended for
ordinary purposes, as the presence of salt tends to absorb atmospheric
moisture.

(5) Boiling in oil is resorted to for special purposes, both for
preservation and to give strength. For example, the best handscrews
are so treated. The oil also prevents glue from sticking, the most
frequent cause of injury to handscrews.

(6) There are a number of "impregnation" methods of preserving timber,
and their practice is spreading rapidly. Of the various preservative
processes, those u