Combustion 



bellows. The fire revives and increases at 

 every puff. The coal, at first dark red, 

 becomes bright red and then glowing white. 

 The air has brought new life to the heart of 

 the fire. What do we do on the other hand 

 to prevent the fuel from being consumed too 

 quickly ? We cover it with ashes and thus 

 preserve it from contact with the air. Under 

 the layer of ashes the coal remains red, but 

 is not consumed. So the fire on the hearth is 

 only kept up by the constant arrival of air. 

 The quicker and more lavish the dissolution, 

 the higher the degree to which the heat is raised. 

 The dissolution which is effected in our 

 fires in a violent manner, with the production 

 of great heat, is not the only way in which 

 coal, or carbon, is consumed. A piece of 

 wood exposed to the weather turns brown 

 after a time, gradually falls to pieces and at 

 last drops into dust. Now, this destruction 

 of wood can be compared at every point with 

 that which takes place in a stove. It is still 

 combustion, but so slow that the heat thrown 

 out is almost or completely imperceptible. 

 The rotting wood gradually dissolves its 

 carbon into the air, which carries it away in 

 an invisible condition ; and as a consequence 

 of these incessant losses, the trunk of a tree 



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