The Manufacture of Charcoal 231 



thrifty were these denizens of the woodland with their 

 rustic wooden huts and piles of rifted firewood, but the 

 industry was almost a thing of the past till again called 

 into active existence by the exigencies of the war. 



Kiln-burning. The kiln is made of brick, one course 

 being sufficient, if bands of iron be added to strengthen the 

 brickwork. It is usually conical in shape, 24 ft. in diameter, 

 with an equal height, and holds about forty cords of wood. 

 The wall of the kiln is carried up nearly straight for about 

 6 ft., when it is gradually drawn in and made a blunt cone 

 shape. A plate of iron is fastened on the top in the manner 

 of a stone to an arch. Three-inch hoop- iron bands, about 

 an eighth of an inch thick, are placed around the kiln and 

 drawn together by means of screw-bolts and nuts. At the 

 base, and near the top, are double sheet-iron doors, by which 

 it is filled with wood or emptied of charcoal. The time 

 required to fill, burn and empty is about three weeks. 

 Pit-burning, for estate purposes, is, however, most com- 

 monly pursued, and has this advantage that the charcoal 

 can be made at any place where timber is being felled, 

 without extra expense, save that of the cartage of the 

 charcoal, whereas in using the kiln or retort the wood must, 

 in most cases, be conveyed to the place where it is erected. 

 Comparative Value of Woods for Charcoal-making. 

 Amongst home-grown timber, oak, ash, and beech are 

 generally preferred for charcoal making, but the following 

 table will show pretty correctly the proportionate relative 

 values of the various descriptions of wood for gunpowder 

 charcoal : 



Per Cent. 

 Rhamnus frangula contains . . . . .27 



Laburnum ........ 25 



Boxwood ........ 24 



Sweet Chestnut . . . . . . .23 



Oak . .22 



Holly 20 



Walnut 20 



Beech 19 



Sycamore . . . . . . . .19 



Elm . . . 19 



Willow . 18 



