90 CLOVER CUI/TURE. 



destructive process occurs. Along- with the carbonic acid formed, there 

 is separated a considerable amount of free hydrogen, the inflammable sub- 

 stance of common illuminating gas. If now, the water supply becomes 

 exhausted, the micro-organisms die, or at least their activity ceases and 

 fermentation stops. If there is any further rise in temperature it is not 

 due to fermentation, but to the spontaneous oxygenation similar to that 

 which occurs in cott6n waste. Such oxygenation can only occur, as was 

 before said, when the body is porous enough to admit the air, and rise oi 

 temperature can only take place when the generated heat is prevented 

 from escaping. The greater the mass, the more favorable the condition 

 for this last. The dryer this mass, the more inflammable it is, and the 

 more pronounced becomes its non-conducting quality in regard to heat. 

 It may be said by some that little moisture, as in the case of coal, favor* 

 spontaneous combustion; but this is only true when by some chemical 

 action the hydrogen of the water is liberated, a process not likely to 

 occur in heated herbage. 



From this it may be inferred: 



1st. That spontaneous combustion of stored vegetable matter ma}' 

 occur. 



2nd. That this can take place only when a considerable number of 

 conditions are favorable at one and the same time. 



3rd That just enough moisture to allow very active fermentation 

 to proceed for a time and then become exhausted, is one of these con- 

 ditions. 



4th. That great bulk and exposure to heating effects of the sun (ag 

 under an unventilated roof) with the above (3rd.) may be considered 

 seriously dangerous. 



5th. That contrary to this no such danger threatens silos as usually 

 filled, however hot the material seems to become." 



