BEST TIME yOR CUTTING TIMBER. 339 



In another point of view, the amount of water is important to be known, for the dif- 

 ference between taking green and dry wood to market, as well as in its consuming, is very 

 great ; and so also, as ample experience proves, there is a material difference in burning 

 green and dry wood. The quantity of water in the wood varies from 20 to 50 per centum, 

 and probably the average amount will not differ much from 36 or 40 per centum. This 

 water is not only of no use to the fire-wood, but it is prejudicial, as it must be dissipated 

 by heat, in which act heat or caloric becomes latent and lost, especially if the wood is 

 consumed upon a hearth or in a stove. 



In addition to the effect of water in diminishing the combustibility of wood, the alkalies 

 have also considerable influence of this kind. Elm, which is a potash wood, burns with 

 less freedom than hickory, which contains much lime. It is, however, possible that the 

 size of the pores of wood may modify its combustibility. Black oak is a notable instance 

 of a slow and drizzling combustion : the pores are large and numerous, from which the 

 watery sap continually oozes. 



