Preparation of Charcoal. 149 



597. When the sweating stage is over, the openings around the 

 base should be partly closed, but some vent-holes must be left for 

 the escape of gases. If hollow places form, the cover must be re- 

 moved, and their place hastily filled in with wood. The process 

 must be watched day and night until it is completed, which is known 

 by the color of the smoke. The time required for cooling is gener- 

 ally about three weeks. The meiler is then packed as closely as 

 passible, to exclude the air, and when cool enough the coals are 

 drawn out. 



598. It is stated from experience that it is best not to wait until 

 the fire is wholly extinguished, but to quench with water such sparks 

 or burning places as are found. 



599. Sometimes a meiler is made higher and narrower than in the 

 preceding figures, and in every form it is convenient to have plat- 

 forms around the sides, at one or two level<, so as to be able to reach 

 conveniently every part. In the annexed figure, a, 6, represents the 

 central opening for 



applying the fire, c, 

 d, a bank of earth, 

 with a step at e. An 

 upper step, g, is sup- 

 ported by braces on 

 various sides, as at/, 

 and near the top the ?g gection Qf & Me , lpf nr p 1 . pit< prepared for Firing> 



COVer is laid Open UU- as Practiced in Bavaria. 



til the whole part is well ignited, and the steam has principally 

 passed off. 



600. It is sometimes preferred to burn charcoal in kilns. They 

 are generally made of brick, and the following sizes, among others, 



are in use : 



Length. Width. Height. Capacity (Cords.) 

 Used in New England j g feet. 12 feet. 12 feet. 5->feet. 



Type of those used in Mexico 40 " 1!) " 18 " 75 " 



A kind used in Michigan 48 " 17 ' 18 " 90 ' 



It requires from 35 to 40 M. of brick for a kiln of 45 cords, and 

 60 to 65 M. for one of 90 cords. These rectangular kilns are arched 

 at the top, and supported externally by a wooden framework, and 

 iron tie rods. They have an iron door (d) capable of being made 

 air-tight, and near the top a smaller door (e) for filing the upper 



