216 CARBONIZING IN ORDINARY KILNS. 



ed respectively as represented in A and B of Fig. 68. As the 



Fig. 68. 



Mode of construoting flue of horizontally-laid p araioloidal Mine. 



horizontal position of the pieces precludes any tendency for them 

 to fall in, no posts are necessary to support the sides ; hut to help 

 to form the flue straight and vertical, a straight hillet may be held 

 upright in it until the kiln has been built up. 



The firing can of course take place only from the top, in the 

 manner described on page 186. The management of the covering 

 is, however, at first different. Since there is absolutely no danger of 

 over-rapid combustion ■within the pit, the sides at the ground-level 

 should be kept open for some time to allow the fire to spread freely 

 downwards, and, in order to prevent the wood at the top from burn- 

 ing too fast in the meanwhile, no vent-holes should be pierced there. 

 It is only when the wood within the pit is in full combustion that 

 the covering near the ground should be completed, but even then 

 it should be lighter there than elsewhere, and a vent or two may 

 have to be left on a level with the ground up to the very end of the 

 carbonization. Some charcoal-burners, in order to introduce a 

 draught into the pit, excavate a narrow oblique shaft in the sides of 

 the pit at the two extremities of a diameter and opening into the 

 bottom of the pit. Needless to say that the shafts are not closed 

 at all until carbonization is complete. 



By stacking horizontally we secure the very signal advantage of 

 being able to utilise pieces of all lengths and thicknesses, thus sav- 

 ing the very heavy cost, imposed by the vertical method, of cutting 

 up all the pieces to one length and of splitting them to more or 

 less the same thickness, and also being able to build up a kiln with 

 the produce of the few nearest trees. It is mainly on this account 

 that the Indian charcoal-burner always lays his wood horizontally, 

 and will have nothing to say to vertical stacking, even when the 

 circumstances of the case render that method preferable. 



