The Republican journal., 1915-01-28
THE FUEL VALUE OF WOOD,

The fuel value of two pounds of wooC
is roughly equivalent to that of one
pound of coal. This is given as the re
suit of certain calculations now being
made IN the forest service laboratory,
which shows also about how many cords
of certain kinds of wood are required to
obtain an amount of heat equal to that
in ton of COAL
Certain kinds of wood, such as hickory,
oak, beech, birch, hard maple, ash, elm,
locust, longleaf pine and cherry, have
fairly high heat values, and only one
cord of seasoned wood of these species
is required to equal one ton of good COAL.
1t takes a cord and half of shortleaf
pine, hemlock, red gum. Douglas tir,syc-
amore, and soft maple to equal a ton of
coal, and two cords of cedar, redwood,
poplar, catalpa, Norway pine, cypress,
Eastwood, spruce and white pine.
Equal weights of dry, nonresinous
woods, however, are SAID to have practi-
cally the same heat value regardless of
species, and as consequence it can be
stated as general proposition that the
heavier the wood the more heat to the
cord. Weight for weight, however,
there is very little difference between
various species; the average heat for all
thai have been calculated is a, 900 calor
les, or heat units, per kilogram. A kill
ogram of resin will develop g. 400 heat
units, or about twice the average for
wood. AS a consequence, reslnous woods
have a greater heat value per pound than
nonresinous woods, and this increased
value varies, of course, with the resin
content.
The available heat value of a cord of
wood depends on many different factors.
1t has a relation not only to the amount
of resin it contains, but to the amount of
moisture present Furthermore, cords
vary as to the amount of solid wood they
contain, even when they are of the stand
ard dimension and occupy 1913 cubic feet
of space. A certain proportion of this
space is made up of air spaces between
the sticks, and this air space may be
considerable in a cord made of twisted,
crooked, and knotty sticks. Out of the
1913 cubic feet a fair average of solid
wood is about so cubic feet.
1t is pointed out, however, that heat
value is not the only test of usefulness
in fuel wood, and since 95 per cent of all
wood used for fuel is consumed for do
nestle purposes, largely in farm houses,
such factors as rapidity of burning and
ease of lighting are important. Each
section of the country has its favored
woods, and these are said to be, in gen
eraI. the right ones to use. Hickory, of
the nonresinous woods, has the highest
fuel value per unit volume of wood and
has other advantages. 1t burns even
ly, and, as the housewives say, holds
the heat. The oaks come next,
followed by beech, birch and maple.
Pine has relatively low heat value per
unit volume, but has other advantages.
1t ignites readily and gives out quick
hot flame, but one that soon dies down.
This makes it tavorite with rural house
keepers as summer wood, because it is
particularly adapted for hot days in the
kitchen.
The fuel qualities of chestnut adapt it
particularly to work in brass foundries,
where it gives just the required amount
of heat, and it is therefore in favor.
Coastwise vessels in Florida pay twice as
much for Florida buttonwood as for any
other, because it burns with an even heat
and with a minimum amount of smoke
and ash.
The principal disadvantage of the res
inous pines is their oily black smoke.