Local Distribution of Water in Wood

As seasoning means essentially the more or less rapid evaporation of
water from wood, it will be necessary to discuss at the very outset
where water is found in wood, and its local seasonal distribution in a
tree.

Water may occur in wood in three conditions: (1) It forms the greater
part (over 90 per cent) of the protoplasmic contents of the living
cells; (2) it saturates the walls of all cells; and (3) it entirely or
at least partly fills the cavities of the lifeless cells, fibres, and
vessels.

In the sapwood of pine it occurs in all three forms; in the heartwood
only in the second form, it merely saturates the walls.

Of 100 pounds of water associated with 100 pounds of dry wood
substance taken from 200 pounds of fresh sapwood of white pine, about
35 pounds are needed to saturate the cell walls, less than 5 pounds
are contained in the living cells, and the remaining 60 pounds partly
fill the cavities of the wood fibres. This latter forms the sap as
ordinarily understood.

The wood next to the bark contains the most water. In the species
which do not form heartwood, the decrease toward the pith is gradual,
but where heartwood is formed the change from a more moist to a drier
condition is usually quite abrupt at the sapwood limit.

In long-leaf pine, the wood of the outer one inch of a disk may
contain 50 per cent of water, that of the next, or the second inch,
only 35 per cent, and that of the heartwood, only 20 per cent. In
such a tree the amount of water in any one section varies with the
amount of sapwood, and is greater for the upper than the lower cuts,
greater for the limbs than the stems, and greatest of all in the
roots.

Different trees, even of the same kind and from the same place, differ
as to the amount of water they contain. A thrifty tree contains more
water than a stunted one, and a young tree more than on old one, while
the wood of all trees varies in its moisture relations with the season
of the year.

Seasonal Distribution of Water in Wood

It is generally supposed that trees contain less water in winter than
in summer. This is evidenced by the popular saying that "the sap is
down in the winter." This is probably not always the case; some trees
contain as much water in winter as in summer, if not more. Trees
normally contain the greatest amount of water during that period when
the roots are active and the leaves