110 
STRUCTURE OF WOOD, &C« 
Combustion ot According to the analyses of Messrs. Gay Lussec and 
wood and its . , ‘ _ , , . 
charcoal. 1 henard, 100 parts or oak, perfectly dry, contain 52*54 parts ot 
carbon j and 100 parts of beech contain 51 * 45 . 
Now as it seems to me extremely probable that the dry 
ligneous substance is palpably the same in ail woods j I shall 
take the medium term of the results of these two analyses, and 
consider it as an indubitable fact, that 100 parts of perfectly 
dry wood contain 52 parts of carbon. 
Therefore, as 100 parts of seer- wood furnished me with 
only 43 of charcoal ; we must Conclude, if dry charcoal be con- 
sidered as carbon, that of the 52 parts of carbon contained in 
100 parts of seer-wood, 9 are taken up in the composition of 
the pyroligneous acid formed in the carbonisation of the wood. 
Which 19 parts make more than 17 per cent, of all the carbon 
contained in the wood. 
Though charcoal should not be purely carbon, we must, 
nevertheless, admit that there is still a much greater proportion 
of carbon employed in the formation of that acid, or of other 
substances which fly off into the atmosphere during the pro- 
cess of the carbonisation of the wood. 
In pursuing inquiries in natural philosophy, the first object 
that demands attention, is to keep an accurate account of 
weights ; and so long as we proceed with the balance in 
hand, there is little hazard of being misled. 
And here, before I proceed farther in the inquiry into the 
sources of the heat developed during the combustion of wood, I 
shall exhibit a general table of the details and result of 43 
experiments, made upon 1 1 different kinds of the woods of our 
climate. As 1 shall have occasion to refer to some of these 
experiments, for the establishment of facts, it is requisite that 
they should first be known. 
All these experiments having been made and registered long 
before I began the calculations ultimately adopted for the eluci- 
dation of their results ; I have not hesitated to rely on them. 
And farther, as they were made with all possible care, and with 
instruments, to me apparently perfect 5 I can answer for their 
accuracy. 
New experiments ever bear a certain value $ all the know- 
ledge which constitutes the imperishable riches of mankind, 
consists only of accurate statements of well-conducted experi- 
ments. Happy they who have the good fortune of contributing 
something to the general stock ! Heat 
