342 



FOREST PRODUCTS 



maining moisture from green wood. The following table 

 shows the per cent of available heat given out by wood burned 

 at different moisture contents: 



Condition of Wood. 



Kiln dry 



Air dry (split).. , 

 Air dry (chunks) 



Half dry 



Green 



3. The character of seasoning. Some woods decay if left in the 

 open before they are thoroughly seasoned. This may hold 

 true of beech, birch and other woods under certain conditions. 



4. The rapidity of burning. When certain woods are burned too 

 rapidly full heat values are not derived. 



The average heating value of dry wood has been determined to be 

 4600 calories per kilogram or 8028 British thermal units per pound. 



The following table^ shows the relative fuel value of non-resinous 

 woods based upon their specific gravity. 



Hickories, average. 

 Oaks, average. ... 



Beech 



Birch 



Maple 



Ash 



Elm 



Tamarack 



Chestnut 



Douglas fir 



Hemlock 



Lodgepole pine. . . , 



White pine 



Redwood 



White fir 



Spruces, average . . 

 Alpine fir 



In respect to resinous woods the fuel values can only be appro.xi- 

 mated according to the resin content. It is said that the caUforic value 



1 From " Fuel Value of Wood," by H. S. Betts and E. Bateman, 1913. U. 3. Forest 

 Service. 



