180 Sfall Manure and Straw. [April, 



which have been sprinkled with water, are left standing until they 

 pass into fermentation or putrefaction. 



Heat is generated by most chemical processes, and in most con- 

 siderable degree by those which resemble combustion. Digestion 

 and respiration have been shown to be such processes ; so also are 

 putrefaction and decay. For this reason, we perceive a visible and 

 spontaneous evolution of heat, wherever considerable quantities of 

 animal or vegetable matters putrefy, decay, or rot. Hence soil rich 

 in humus ( for humus must be considered vegetable fiber undergo- 

 ing decay or slow combustion) will always preserve a greater amount 

 of warmth than the soil which is poor in this ingredient, and this 

 the more, because on account of its dark color it absorbs a larger pro- 

 portion of the rays of the sun than a soil of lighter color. The 

 heating of stall-manure is thus explained at once ; it will be stron- 

 ger in proportion to the larger masses heaped on each other, and to 

 the abundance of azotized substances they contain, inasmuch as 

 these latter produce a brisker putrefaction ; in the first case, how- 

 ever, the heat is better kept together, and is constantly generated 

 anew, because with increasing temperature the putrefactive process 

 is more energetically carried on. 



Next to heat, air and water have an essential influence upon the 

 progress of putrid disintegration in organic matter. Substances 

 from which all water has been removed by drying, do not suffer this 

 decomposition, as is exemplified in dried fruits, seeds, leaves, etc., 

 which we can preserve for years, while in a moist state they soon be- 

 come corrupt. "With a moderate degree of moisture, decomposition 

 proceeds most rapidly and successfully. An excessive quantity of 

 water retards it, because when substances are entirly covered with 

 water their heating, and at the same time the access of air, are pre- 

 vented. 



The exclusion or non-exclusion of aiV from fermenting vegetable 

 and animal remains, occasions a great difference in the nature of 

 the decomposition. In the first case, as, for example, in the decom- 

 position of animal manure when piled together in large and com- 

 part heaps, and of urine in the drainings' resevoir, in the steeping 

 of flax, in the fermentation of potted cheese, etc., gases and vapors 

 of highly disagreeable odor are generated, which may be regarded as 

 partially consumed substances ; they are produced from want of air, 

 or, more accurately speaking, of oxygen. This decomposition is 

 called, ii\m\)\y, putr(f(tct[on. It has the greatest analogy to charring 



