CHARCOAL-MAKING. 529 



the best class of firewood and even timber may be used for 

 this purpose, according to the demands of neighbouring works 

 for charcoal. 



Any species of wood may be carbonised, but the method 

 employed varies with its density and greater or less combusti- 

 bility. If two kinds of wood are placed in the same kiln one of 

 which must remain some time burning in the kiln until the 

 other is carbonised, the former might be burned to ashes 

 before the latter can be removed. It is therefore advisable 

 to pile only one species of wood at a time in a kiln ; if different 

 species must for any reason be burned in the same kiln the 

 precaution should be taken to restrict these to hardwoods or 

 softwoods only, or to split the harder woods and place them 

 in the centre of the kiln, where the heat is greatest. It is, 

 however, always better to separate the woods, as charcoal made 

 from different species is used for different purposes. 



As regards the comparative soundness and dryness of wood 

 for charcoal-making, it is customary to use only sound air-dried 

 wood, and not dead wood, liotten wood is useless for the purpose, 

 and must be excluded carefully. Carbonising broken billets is 

 a difficult process, as the pieces continue to glow for a long time 

 and may set fire to the kiln during the removal of the charcoal. 



All wood for carbonisation should be spread out in dry parts 

 of the felling-area or of landing depots until it is air-dry, in 

 order that there may be the least possible waste of heat in 

 driving off moisture from the wood. Only in very hot summers, 

 or when the wood is highly resinous, is it advisable to use some- 

 what green wood so that the process may not be too rapid, or 

 else the workmen may not be able to keep the combustion of 

 the wood well in hand. 



The shape and dimensions of the billets have considerable 

 influence on the process of carbonisation. Although all parts 

 of a kiln do not burn at the same rate, yet it is advisable to 

 have the billets as uniform in shape as possible. As a rule, 

 therefore, only one assortment of wood is used in a kiln ; only 

 in cases of necessity, in very large kilns or in carbonising 

 stump-wood, should deviations from this rule be allowed. 

 One of the chief points of difference between the common 

 and Alpine methods of carbonisation is that, in] the former, 



F.U. M M 



