Combustion 



different degrees in the way of burning. An 

 old rotten trunk of a tree, a haystack becom- 

 ing heated, a log flaming on the hearth, all 

 show so many different degrees in rapidity of 

 combustion. 



We can derive coal from apples, or meat, 

 or anything which can rot. We will take 

 bread first and place a piece on the red hearth. 

 The bread smokes, turns black and, if we wait 

 long enough, there will be nothing left but 

 carbon. That this carbon comes from the 

 bread is evident, and as we can only give what 

 we have, the bread which gives the carbon 

 must have had it originally, but concealed, 

 hidden among other things which prevented 

 us from seeing it. These other things are 

 gone, driven away by the heat, and now the 

 carbon, stripped of its surroundings, appears 

 black and crackling as its real self. Similarly 

 the apple which you put to bake in the oven, 

 would end by turning into a lump of coal. 

 Flesh, submitted to the prolonged action of 

 fire, becomes coal, as shown by those cutlets 

 forgotten in the pan. Enough ! the result 

 would always be the same. Everything 

 which forms a part of the plant or the animal 

 contains coal or carbon, and by decaying 

 dissolves this carbon in the air. 



27 



