532 AUXILIARY FOREST INDUSTRIES. 



even 25 % (according to v. Berg). The reason for this is that 

 charcoal dust mixed with earth gives the proper degree of 

 porosity to the soil that is most advantageous for charcoal- 

 making. The charcoal-burners, therefore, always prefer old 

 sites for kilns, and changing a site is always disadvantageous. 

 Although as far as possible suitable sites are chosen for 

 kilns, yet in mountainous forests it is often necessary to make 

 one on a slope, in a narrow gorge or other unfavourable place. 

 Then an excavation is made in the hill-side and an embank- 

 ment formed downhill so as to secure a horizontal site. It is 

 then better to support the lower side of the site by wattle- 

 work, or logs may be piled on one another and covered with 

 earth to form the lower side of the site. Kilns made on sites 

 like these always have a draught in one particular direction, 

 which the burners must try to counteract by various devices 

 whilst the kiln is burning. There must be round the kiln a 

 clear space sufficiently large for the burners to work in and 

 affording room for the charcoal-burners to stack the wood, also 

 for a hut and so on. 



iv. Erection of the Kiln. 



At the centre of the kiln is a flue, which is constructed of 

 three or four stakes driven into the ground about one foot 

 apart. They are bound round with withes, forming a hollow 

 shaft, which is filled with very dry, combustible firewood. The 

 way in which the latter is inserted depends on whether the 

 kiln is to be kindled from above or below. In the latter case 

 a dry board is placed under the flue to keep back the soil- 

 moisture ; highly combustible fuel, such as pieces of resinous 

 wood, shavings, birch-bark, etc., are then placed upon the 

 board, the upper part of the flue being filled somewhat loosely 

 with broken branches, half-burned bits of wood, shavings, etc. 

 When the kiln is kindled from above, the flue is filled in the 

 reverse manner. 



The flue once filled, finely split pieces of dry wood and 

 partly carbonised billets are placed around it, the spaces 

 between them being filled with wood-shavings, and then the 

 regular kiln is constructed. This is done by piling two tiers 

 of billets, the burner placing dry pieces of wood as closely as 



