468 Inquiries relative to the Structure of Wood. 



53 parts of carbon in 100 of seerwood, but 100 parts 

 of seerwood yielded me only 43 parts of charcoal; this 

 difference, however, it is easy to explain, as will be seen 

 in the sequel. 



SECTION VII. Of the Quantities of Heat developed in 

 the Combustion of different Species of Wood. 



Many persons have already endeavoured to determine 

 the relative quantities of heat furnished by wood and 

 charcoal in their combustion ; but the results of their 

 inquiries have not been satisfactory. Their apparatus 

 has been too imperfect, not to leave vast incertitude in 

 the conclusions drawn from their investigations. In- 

 deed, the subject is so intricate in itself, that with the 

 best instruments the utmost care is requisite, lest, after 

 much labour, the inquirer should be forced to content 

 himself with approximations instead of accurate results 

 and valuations strictly determined. 



All woods contain much moisture, even when ap- 

 parently very dry ; and as the persons alluded to have 

 neglected to determine the quantities of absolutely dry 

 wood burned by them, much uncertainty prevails in the 

 results of all their experiments. 



Another source of uncertainty lies in the great quan- 

 tity of heat suffered to escape with the smoke and other 

 products of the combustion. 



As the calorimeter used in my experiments has been 

 described in a memoir which I had the honour to pre- 

 sent to the Class on the 24th of February, 1812, it is 

 unnecessary here to resume that subject ; suffice it to 

 explain, in a few words, the various precautions I 

 adopted in burning wood under the calorimeter. 



