108 



PROPERTIES OF WOOD. 



In the last method the amount of heat necessary to raise a 

 unit of water 1 C. is termed a calorie. The heating-power of 

 air-dry wood is given as equivalent to 3,620 calories, charcoal 

 at 8,080 calories. Hence one kilogram of wood or charcoal 

 will raise the temperature of 3,620 or 8,080 litres of water 

 by 1 C. 



The latest results by Bersch * are as follows : 



Heat-units. 



Charcoal 7,000 



Half-charred (red) ditto 3,980 



Absolutely dry wood 3,600 



Wood containing i 

 Limewood ,, 

 Maple ,, 



Poplar ,, 



Beech ,, 



Spruce , , 



Ash ,, 



Hornbeam ,, 

 Oak 



The heating-effect reckoned in calories, depending on 

 weight, shows that there is little difference in the heating- 

 power of the different woods. But as in commerce wood is 

 dealt with by volume and not by weight, only statements 

 giving the heating-effect according to the volume of wood 

 consumed, that is termed the specific-heat effect, are of 

 practical importance. 



The following tabular statement gives the specific-heat effects 

 of wood as compared with that of pure carbon (100) : 



S I' K( ' 1 FTC- HE A T E I- 1 FECTS. 



. " Die Yervverlmi- des 1 lol/.cs auf eliemisrlien WCL;.'' \Vicn. IS'.). 1 !. 



