Inquiries relative to the Striicture of Wood. 479 



According to the results of Crawford's experiments, 

 which we have found to be very accurate, i pound of 

 charcoal furnishes in its combustion only the necessary 

 heat for raising 57.608 pounds of water 180 F. ; there- 

 fore the charcoal contained in i pound of dry lime-wood, 

 equal to 0.4359 pound, can furnish in its combustion no 

 more heat than is necessary to raise 25.111 pounds of 

 water 180; but as the experiment has given 43.141 

 pounds, there must certainly have been some other sub- 

 stance burned beside the charcoal, and which could have 

 been none other than hydrogen. 



Before we determine the quantity of hydrogen con- 

 sumed, it is essential to ascertain how much heat has 

 been furnished, not merely by the charcoal itself, but 

 by the charcoal and the carbon contained in the wood ; 

 for it is very certain that all the carbon was burned, 

 since no pyroligneous acid was formed. 



According to the analyses of Messrs. Gay Lussac and 

 Thenard, i pound of dry wood contains 0.52 pound of 

 carbon. 



If we adopt Crawford's estimate, we shall find that 

 the combustion of 0.52 pound of carbon ought to fur- 

 nish heat sufficient to raise 29.956 pounds of water 

 1 80 F. 



Deducting this quantity of water from that given by 

 the experiment, namely, 43.141 pounds, we shall have 

 13.185 pounds as the measure of the heat produced by 

 the combustion of the hydrogen consumed in the experi- 

 ment. 



From the results of this inquiry we may conclude, that 

 of the heat manifested in the combustion of wood, 

 rather more than two thirds are produced by the com- 

 bustion of the carbon, and a little less than one third by 

 the hydrogen consumed. 



