As part of a study of the charring rate of wood, I determined the higher heating values (gross heat
of combustion) and the chemical composition of samples from four hardwoods and four softwoods.
The higher heating value of wood was correlated with lignin and extractive contents. There was a
highly significant linear correlation between the higher heating value of the extractive-free wood and
lignin content. Equations are presented that can be used to determine the higher heating value of
extractive-free wood when the Klason lignin content is known. The equations should be useful to
those interested in using a variety of species of wood as fuel.