— 69 — 



(2) Close the lower part of the mouth and then kindle from the 

 above. Since the kindle hole is made at the top of the mouth kindling 

 is troublesome and besides there is an undesirable large production of ashes 

 not much different from the above case in percentage. 



Owing to these disadvantages, we have arranged to shut up the 

 lower portion of the mouth, and have succeeded in kindling from the 

 upper portion by setting out the necessary eaves. As soon, however, as 

 the fire attacks the billets under the roof of the kiln, the upper half of 

 the mouth is likewise closed, allowing to pass the necessary draft through 

 a small passage opened in the centre of the base. By this device, we 

 could avoid the direct contact of the air with burning billets. Still, the 

 air passage at the centre of the base often causes the excessive oxidation 

 of the neighboring billets and conversion into ash, owing to the constant 

 fall of scintillating charcoal dust from the roof. For this defect, two 

 kilns were so combined into a set as to form an air passage at the centre 

 of the two, and this happily well removed the disadvantage. 



IV. Temperature of Carbonization 



Owing to the various uses of charcoal in this country on one side 

 and to the many tree species used for its material on the other, we 

 are in possession of many grades of charcoal varying in hardness, ease of 

 kindling, species of wood, and mode of fabrication. According to the 

 researches of Violett, the igniting point of charcoal is proportional to the 

 temperature of carbonization. Thus, charcoal produced at a low heat 

 kindles readily at low temperature while that which was burnt at a 

 high temperature requires a high heat to kindle it. Still, carbonization, 

 unlike dry distillation of wood, is never brought about by heat from the 

 outside. On the contrary, in carbonization the wood is oxidized by heat 

 from itself, so that any regulation of that heat is hardly practicable. 

 Such regulation is only effected in some extent by admitting air to the 

 red heated charcoal in the kiln after carbonization. 



In our researches, to establish the relation of the hardness and 

 igniting point of charcoal, we have examined the carbonization temperature 

 inside the kiln for the " Inside Kiln Extinction Method ; " as well as for 

 the " Outside Kiln Extinction Method " and the temperature observed at the 

 moment of the introduction of air after the carbonization are as follows : — 



