COS WUOIJ-CAKBONISATIOX. 



height of the kiln ; or, sis it is easier to measure the girth than 

 the diameter of completed kilns, '^y ^ 4 ^ 2 ~ 8" ~ 25'12 

 nearly. As, however, the shape of a kiln is usually not quite a 

 paral)oloid, but somewhat steeper and more pointed, 4 — 6 % may 

 be deducted. Some useful tables* have been prepared for the 

 cubic contents of kilns. It is easy to calculate the volume of a 

 kiln whenever wood already stacked is used. 



Kilns vary greatly in size in ditterent districts ; sometimes, as 

 in the Spessart, Thuringia, &c. they contain only 400 — 700 

 Ptaeked cubic feet (12 — 20 st. cub. meters), whilst in the Harz 

 they may be five times as large, and ten times as large in the 

 Alps. Such large kilns, however, resemble those formed on the 

 Alpine plan, in the common method a kiln of 2,000 — 3,500 

 St. cub. feet may be considered large and one of 400 — 1,000 st. 

 cub. ft., small. 



The size of a kiln is not without influence on the way it is 

 fired, on the quality and quantity of charcoal and the cost of 

 carbonisation. Small kilns require comparatively more fuel for 

 kindling and more space than l^rge kilns and also involve more 

 work and supervision ; they are however more easily managed in 

 the forest, the transport of the Avood to them is less costly, they 

 may be burned with less fear of firing and usually yield harder 

 charcoal than large kilns. 



It is difficult to say whether large or small kilns yield com- 

 paratively a greater or less percentage of charcoal for the 

 amount of wood employed. Each district considers its own 

 form of kiln the best ; in the Harz and Alps large kilns are 

 preferred in this respect, and small kilns on the Khine and in 

 Franconia. The size of the kiln therefore is probably not an 

 important factor in the question of comparative yield, which 

 is chiefly decided by the skill of the burners. The size of the 

 kilns in fact depends on whether every year large quantities of 

 wood are carbonised or there is only a small local demand for 

 charcoal, also on experience as to the comparative cost of large 

 or small kilns. 



• Bohmt-rle, Tabclkn ziir IJercclmung dcr Kiibiciiilialte sU-liciider Ko1i1iii(.m1(,t. 

 Wien, 1873, 15raumulkT. 



