DECAY OF ORGANIC MATTERS. 239 



manure, that which is in most general use, is precisely that which 

 by its complex nature contains all the fertilizing principles required 

 in ordinary tillage. 



Particular cultures may demand particular manures ; but the stand- 

 ard manure, such as farm dung, for example, when it is derived from 

 good feeding, supplied to animals with suitable and abundant litter, 

 affords all the principles necessary to the development of plants ; 

 such manure contains at once all the usual elements which enter 

 into the organization of plants, and all the mineral substances which 

 are distributed throughout their tissues ; in fact, carbon, azote, hy- 

 drogen, and oxygen are found therein united with the phosphates, 

 sulphates, chlorides, &c. 



In order to be directly efficacious, every manure must present 

 this mixed composition. Ashes, gypsum, or lime spread upon bar- 

 ren land, would not improve it in any sensible degree ; azotized or- 

 ganic matter, absolutely void of saline or earthy substances, would 

 probably produce no better effect ; it is the admixture of these two 

 classes of principles, of which the first is derived definitively from 

 the atmosphere, while the second belongs to the solid part of the 

 globe, which constitutes the normal manure that is indispensable to 

 the improvement of soils. 



Dead organic matter, subjected to the united influence of heat, of 

 moisture, and of contact with the air, undergoes radical modifica- 

 tions, and passes by a regular course of transformation into a con- 

 dition more and more simple. The tissues, so long as they form a 

 part of the animated being, are protected against the destructive ac- 

 tion of the atmospheric agents ; in plants and animals this protec- 

 tion is not extended beyond the period of their existence ; destruc- 

 tion commences with death, if the accessory circumstances are suf- 

 ficiently intense ; and then ensue all the phenomena of decomposi- 

 tion, of that putrid fermentation which, at the expense of the primi- 

 tive elements of the organized being, generates bodies more stable 

 and less complicated in their constitution, and which present them- 

 selves in the gaseous and crystalline conditions, forms which are 

 affected by the inorganic bodies of nature in general. 



The mineral substances which had been taken up in the organiza- 

 tion become freed, and are thus again restored to the earth. The 

 organized substances which change the most rapidly, are precisely 

 those into which azote enters as a constituent principle. Left to 

 themselves, whether in solution or merely moistened, these sub- 

 stances exhibit all the characteristic signs of putrefaction ; they ex- 

 hale an insupportable odor ; and the result of their total and com- 

 plete decomposition is finally the production of ammoniacal salts. 

 The water wherein the phenomenon is accomplished facilitates it 

 not only by weakening cohesion and enabling the molecules to move 

 more freely, but it assists also by the very affinity which each of its 

 own principles bears to the elements of the substance subjected to 

 the putrescent fermentation. Proust observed that during the de- 

 composition of gluten immersed in water, a mixture of carbonic 

 acid and of pure hydrogen gas is disengaged, a phenomenon which 



