168 MANURES. 



(if not washed away by water, for it is soluble), till 

 wanted by the growing plant. 



316. Animal manures, while in course of prepara- 

 tion, should never be drenched with water, if it can 

 be avoided, for then the potash contained in them, and 

 the soda and chlorine which exist in them in the form 

 of common salt, are dissolved and washed away. On 

 the other hand, they should not be suffered to become 

 entirely dry, as they sometimes will by excessive fer- 

 mentation, but should be kept moderately moist. If 

 too dry, it is difiicult to keep the ammonia from escap- 

 ing ; and besides the loss of ammonia, there is another 

 injurious action which takes place. Farmers gene- 

 rally speak of it as hurning. They say their mj^nure 

 burns. There is more truth in this than would at 

 once be supposed. The manure does burn, or an ac- 

 tion similar to burning takes place. Let us see how 

 this is. When wood burns on the fire, its carbon, 

 about half of the whole, combines with oxygen, and 

 passes off into the air as carbonic acid. Its oxygen 

 and hydrogen pass off in the form of watery vapor, 

 and nothing but a little ash is left. So when manure 

 is suffered to become very dry, and to ferment excess- 

 ively, its carbon combines with oxygen, and passes 

 off as carbonic acid into the air ; the oxygen and hy- 

 drogen pass off as watery vapor, and there is not much 

 left. It is very nearly literal truth, to say, that '' the 

 manure heap has hurnt downy What remains is a lit- 

 tle carbonaceous matter and a little ash, about the 

 same as would have remained if it had been literally 

 burnt in a furnace. The rest has gone into the atmo- 



