124 STALL-MANURE AND STRAW. 



creasing temperature the putrefactive process is more 

 energetically carried on. 



Next to heat, air and water have an essential in- 

 fluence upon the progress of putrid disintegration in 

 organic matter. Substances from which all water 

 has been removed by drying, do not suffer this de- 

 composition, as is exemplified in dried fruits, seeds, 

 leaves, etc., which we can preserve for years, whilst 

 in a moist state they soon become corrupt. With a 

 moderate degree of moisture, decomposition proceeds 

 most rapidly and successfully. An excessive quan- 

 tity of water retards it, because when substances are 

 entirely covered with water their heating, and at the 

 same time the access of air, are prevented. 



The exclusion or non -exclusion of air from fer- 

 menting vegetable and animal remains, occasions a 

 great difference in the nature of the decomposition. 

 In the first case, as, for example, in the decomposi- 

 tion of animal manure when piled together in large 

 and compact heaps, and of urine in the drainings' 

 reservoir, in the steeping of flax, in the fermentation 

 of potted cheese, etc., gases and vapors of highly dis- 

 agreeable odor are generated, which may be regarded 

 as partially putrefied or partially consumed sub- 

 stances ; they are produced from want of air, or, more 

 accurately speaking, of oxygen. This decomposition 

 is called, simply, putrefaction. It has the greatest 

 analogy to charring or dry distillation, where, as, for 

 example, in the manufactupe of common illuminating- 

 gas, or in charcoal piles, from deficiency of air, half- 



