The Story -Book of the Fields 



ends by being reduced to some spadefuls of 

 earth, just as the coal of our stoves is reduced 

 to a few cinders. The same result occurs in 

 all decomposition of animal or vegetable 

 matter. Everything that rots is consumed, 

 that is to say it is dissolved slowly into the air. 



It is easy to explain why the heat which 

 results from combustion caused by rotting is 

 not generally perceptible. Let us suppose 

 that a log will take a year to be consumed by 

 rotting, and that a similar log will take one 

 hour to burn in a fire. In both cases heat will 

 be produced. Only, in the rotting wood, 

 this heat will be produced very slowly and 

 very little at a time, since it has to take a 

 whole year : so it will be imperceptible. As 

 to the wood burning on the hearth, the pro- 

 duction of heat will be fierce and quick, 

 seeing that it is only to last for one hour. 

 Consequently this heat will be keenly per- 

 ceptible. However, if the amount of rotten- 

 ness is large, the heat produced may be per- 

 ceived. In a manure heap the temperature 

 is raised to a high degree ; in a damp hay- 

 stack it may even cause fire. 



Therefore, although the process is really the 

 same, it is well to distinguish between quick 

 and slow combustion, in order to recognise 



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