CHARCOAL 



How charcoal is made. Charcoal may be made by heating 

 wood in an oven to which air does not have free access. The 

 absence of air prevents 

 ordinary combustion, 

 nevertheless the intense 

 heat affects the wood and 

 changes it into new sub- 

 stances, one of which is 

 charcoal. 



The wood which smolders 

 on the hearth and in the 

 stove is charcoal in the 

 making. Formerly wood 

 was piled in heaps (Fig. 

 33), covered with sod or 

 sand to prevent access of 



FIG. 33. Making charcoal. 



oxygen, and then set on 

 fire ; the smoldering wood, 

 cut off from an adequate supply of air, was slowly transformed 

 into charcoal. Later, crude earthen receptacles, or charcoal 

 kilns, were built in rock or hillside and the burning wood was 

 smothered in these. Scattered over the country one still finds 

 isolated charcoal kilns, or crude earthen receptacles in which 

 wood thus deprived of air was allowed to smolder and form 

 charcoal. To-day charcoal is made commercially by piling 

 wood on steel cars and then pushing the cars into strong walled 

 chambers. The chambers are then closed to keep out the air, 

 and are heated to a high temperature. The intense heat trans- 

 forms the wood into charcoal in a few hours. A student can 

 make in the laboratory sufficient charcoal for art lessons by 

 heating in an earthern vessel wood buried in sand. 



A form of charcoal known as animal charcoal, or bone black, 

 is obtained from the charred remains of animals instead o\ 



