STALL-MANURE AND STRAW. 121 



organic or combustible constituents ; inasmuch as 

 these are transformed into a brownish-black, pulver- 

 ulent mass (the well-known humus), whilst a part 

 becomes at the same time aeriform, and escapes into 

 the atmosphere. Coincidently with this, a quantity 

 of water is also evaporated ; and from these two vol- 

 atilizations it is easily understood why fermented 

 manure is of less weight than fresh. If the matter 

 so escaping was exclusively water, this diminution 

 in bulk and in weight would be advantageous and 

 desirable ; for the farmer would thereby save expense 

 in transportation, as he would employ a drier manure, 

 and w^ould possess in a load which had lost half its 

 weight by desiccation the same fertilizing power 

 that is contained in two equal loads of fresh ma- 

 nure. 



The true state of matters is, however, wholly dif- 

 ferent. 



It has been already stated in one of the earlier 

 chapters, that of the proximate constituents of plants 

 two leading classes are distinguished, the combus- 

 tible (organic), and incombustible (inorganic) ; of 

 these, the first alone are capable of fermentation and 

 putrefaction, the latter not. 



It has further been shown, that amongst organic 

 substances a distinction is made between such as con- 

 tain, and such as do not contain, azote or nitrogen, 

 and that the former must be regarded as more scarce 

 and valuable, as well for foddering animals as for 

 manuring plants. Now.it is precisely these azotized 

 11 



