14 TIMBER AND TIMBER TREES. 



as the " ash " of the wood. If, now, the chemist chooses 

 to proceed to extremes, he may raise the temperature 

 still higher, and allow the carbon to burn off in presence 

 of oxygen : in doing this he only completes what we 

 should do if we had burnt the piece of wood in an open 

 fire — excepting, of course, that he controls every step in 

 his experiments, and catches and weighs all the pro- 

 ducts, instead of letting them escape anyhow. 



At the end of his complete combustion, then, the 

 chemist finds a minute remnant, weighing only perhaps 

 one per cent, of the weight of the original piece of wood, 

 and looking like a white or grey fine powdery mass, 

 exactly comparable to the ash of a cigar. 



In this ash — the actual quantity of which, like the 

 charcoal and other substances referred to above, will 

 depend on the species of wood, the part of the stem 

 analysed, its age, the soil on which it was grown, and 

 the time of the year at which the specimen was collected 

 — the chemist will ultimately discover salts of lime, 

 potash, and magnesia, with phosphorus and sulphur, 

 and possibly traces of one or two other elements, such 

 as soda, iron, silica, and manganese. The results of the 

 destructive analysis, therefore, may be summed up as. 

 follows : The piece of wood consisted of 



1. Water about 40 per cent. 



2. "Wood" ^, go 



as compared with the original weight of the fresh, non- 

 shrunken specimen. 



3. The dry wood was composed of: 



(a). Combustible constituents, such as : 



Carbon nearly 50 per cent. 



Hydrogen ... ,, 06 



Oxygen ,, ^ ^_ 



Nitrogen 01 



