BY MIXED MANURES. 289 



2. If the manure is suffered to remain in the yard or cellar 

 for any length of time, it should be covered with muck or 

 earth, in order to absorb the gaseous bodies which will be 

 evolved. 



A series of chemical changes now commence. The whole 

 grows warm, and after a few months crumbles down to a uni- 

 form mass, and becomes short muck or rotted manure ; con- 

 taining a larger quantity of soluble matter (soluble geine and 

 salts) than it did in the green state. This process was for- 

 merly called fermentation, but now it includes the processes 

 oi fermentation, putrefaction and decay. The changes indi- 

 cated by these terms, all agree in this particular ; that new 

 compounds are formed, either by a different arrangement of 

 the elements which compose any one compound in the mass, 

 or by the agency of air and water, whose elements combine 

 with the ingredients of the manures. The matter, which has 

 passed through the animal organs, is much more easily de- 

 composed than it was before, and a series of chemical trans- 

 formations commence. 



(1) When bodies which contain no nitrogen are decom- 

 posed, the gaseous products have no odor ; as when sugar is 

 converted into alcohol and carbonic acid, and in most cases 

 of fermenting liquors, the process is c?i\]ed fcnnentation. 



(2) When bodies containing nitrogen suffer decomposition, 

 and give rise to gases which emit a disagreeable smell, the 

 process is called putrrf action. But these changes are of the 

 same kind, although the latter is most beneficial to the far- 

 mer, as ammonia is generally formed. 



(3) When any body decays at the expense of the oxygen 

 of the air by a kind of slow combustion, it is called a process 

 of decay (" eremacausis^^) and differs from fermentation and 

 putrefaction in the circumstance, that oxygen is absorbed 

 from the air continually ; while in fermentation, if a small 

 quantity of oxygen is admitted to the body, sufficient to com- 

 mence the process, it will continue without further aid from 



