IV.] VARIOUS THEORIES, &c. 95 



and had then taken up water to the extent of 72 per 

 cent. 



Heart of oak took up 75 per cent, oak alburnum 

 93 per cent, of water. Birch took 66 per cent. Pine 

 from 45 per cent, to 57 per cent, according to the 

 quantity of resin, and so on. 



It \vill be remembered that Sachs hung a dried, 

 and therefore cracked, disc of wood in a damp atmo- 

 sphere, and regarded the experiment as concluded 

 when the crack closed : Hartig points out that the 

 wood goes on imbibing water long after the crack 

 closes, to make good the shrinkage, hence his higher 

 numbers. 



The next datum is 



9. The volume occupied by the saturated woody-walls (+ 

 saturated contents) = dr}- volume + (dry volume X water 

 capacity). 



And, again, 



10. The quantity of liquid water in the lumma of the tra 

 cheides, &c. = total water - (dry volume X water capacity). 



By employing these factors and methods, Hartig 

 obtained a huge series of numbers for each tree, 

 tabulating the part of the tree used, the amount of 

 organic substance, of water and of air, &c. at various 



