Wood.

—On account of its relative scarcity and correspondingly high price, wood is no longer a commercial fuel of any consequence. The low heating value of wood as compared with coal makes it a prohibitive fuel except in forest localities. Wood is commonly sold by the cord and no attention is given by dealers to its value in heat-producing capacity.

The desirability of wood as a fuel is chiefly that of reputation. It is usually considered that hickory is the ideal fire wood, dry maple a close second and that oak is next in desirability as fuel; following which are ash, elm, beech, etc., depending on the density of the wood. The price of wood per cord depends on the nearness and abundance of supply.

The actual heating values of different woods as determined by Gottlieb show that per pound of dry wood there is little difference in heat value between different kinds of hard woods, and that pine gives per pound the highest value of all. The table given below was taken from “Steam” published by the Babcock-Wilcox Co.

Kinds
of wood		Per cent.
of ash 		B.t.u. per
pound
Oak 0.37 8,316
Ash 0.57 8,480
Elm 0.50 8,510
Beech 0.578,591
Birch 0.298,586
Fir 0.28 9,063
Pine 0.37 9,153
Poplar1.86 7,834
Willow 3.37 7,926

In considering this table it must be kept in mind that the values are for dry wood per pound.

As given in Kent’s “Engineer’s Pocket Book” the weights of different fuel woods per cord (thoroughly air-dried) are about as follows:

1 cord hickory or hard maple4,500 pounds equal to 1,800 pounds coal
1 cord white oak3,850 pounds equal to 1,540 pounds coal
1 cord beech, red and black oak 3,250 pounds equal to 1,300 pounds coal
1 cord poplar, chestnut and elm 2,350 pounds equal to 940 pounds coal
1 cord average pine 2,000 pounds equal to 800 pounds coal

The above values in pounds of coal may be taken to represent average bituminous coals. As given by Suplee’s “Mechanical Engineers’ Reference Book,” eight samples of coals representing bituminous coals from mines east of the Mississippi River give an average heating value of 13,755 B.t.u. per pound.