1 12 
STRUCTURE OP WOOD, &C. 
Existence and 
developement 
of cSiarcoal in 
wood. 
These experiments might lead to a great number of observa- 
tions ; but I shall endeavour to reduce them to the exposition 
of a few simple facts which they present 
One fact, certainly very curious, and of the first importance 
to the knowledge of the vegetable economy, appears to be 
well established, viz. that the skeleton of trees is pure charcoal, 
and that it exists in a perfect state in wood. 
If this charcoal did not exist, perfectly formed, in wood, 
it could not possibly preserve its form, while its envelope of 
vegetable flesh is destroyed by the fire in the process of car- 
bonisation. 
As the vegetable flesh contains hydrogen as well as carbon, 
it is more inflammable than charcoal, and is consumed at a 
lower temperature ; and, by proper management of the fire, 
it may be totally destroyed without the inclosed skeleton of 
charcoal being injured. 
Some months ago I presented the class with a small sprig 
of charcoal, produced from a piece of oak partially burned 
under my calorimeter. It was nearly all the charcoal contained 
in the piece. All the coat or flesh of the wood burned with 
a brisk flame, and the skeleton of the wood had got red, but 
the heat was not sufficient to consume it. 
The charcoal-maker seldom does more than burn the flesh 
of the wood, and leaves the skeleton of charcoal naked. 
The dry vegetable flesh produces more heat in its combus- 
tion than an equal weight of dry charcoal. 
Shavings scorched in the stove, by a great heat, yield less 
heat in their combustion, than shavings of the same kind of 
wood, whose vegetable flesh has not been touched. See expe- 
riments, No. 5, 6, 7, 8, g, 10, 25, 38, 41, 45. 
In tables of experiments, similar to those registered in the 
preceding table, it is scarcely possible to have errors on the 
greater side j but they may easily enough happen on the lesser. 
We may, therefore, place the more confidence in those wherein 
the quantities of heat manifested have been the greatest. 
In the experiments. No. 13 and 14, the wood of the lime- 
tree, dried over a chafing-dish, was productive of more heat 
than any other wood that I examined. 
The result, it will be seen, was for lib. of this wood burned 
in experiment, 
% 
No. 
