Inquiries relative to the Structure of Wood. 477 



appears to be well established ; namely, that the skele- 

 ton 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 carbonization. 



As the vegetable flesh contains hydrogen as well as 

 carbon, it is more inflammable than charcoal, and is con- 

 sumed at a lower temperature ; and, by proper manage- 

 ment of the fire, it may be totally destroyed without the 

 enclosed 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 coal 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 

 combustion 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 experiments Nos. 5, 6, 7, 8, 9, 10, 25, 



3 8 > 4i, 45- 



In tables of experiments similar to those registered in 



the preceding table, it is scarcely possible to have errors 

 on the greater side ; but they may easily enough happen 

 on the lesser. We may, therefore, place the more con- 



