270 DURABILITY OF MANURES. 



quantity of oxygen (4.6,) the loss of which appears would require 

 no more than 0.57 of hydrogen to constitute water ; and this is a 

 quantity which jt is impossible to answer for in experiments made 

 upon such substances without excessive delicacy of tnanipulation. 

 This much may be certainly concluded, viz.. that manure which has 

 undergone preparation contains a larger relative proportion of azote 

 than the substances which have concurred in its production ; and for 

 this reason, it is very probable that upon the whole a very trifling 

 loss of this element is experienced if the fermentation has heen 

 carefully managed, and the manure has been carried out and dis- 

 tributed upon the land before its decomposition is loo far advanced. 

 This conclusion, which I am particularly anxious to establish, is 

 partly explained by the interesting researches of Mr. Hermann, 

 which go to prove that woody fibre in rotting attracts and fixes a 

 quantity of the atmospheric air. 



Azote is in fact the element which it is of highest importance to 

 augment and to preserve in dung. The organic substances which 

 are the most advantageous in producing manures are precisely those 

 which give origin by their decomposition to the largest proportion 

 of azotized matters soluble or volatile. I say by their decomposi- 

 tion, because the mere presence of azote in matters of organic ori- 

 gin does not suffice to constitute them manure. Coal, for example, 

 contains azote in very appreciable quantity ; and yet its ameliorating 

 influence upon the soil is absolutely null ; this happens from coal 

 resisting the action of those atmospheric agencies which determine 

 that putrid fermentation, the ultimate result of which is always the 

 production of ammoniacal salts, or other azotized compounds favor- 

 able to the growth of vegetables. While we admit the high impor- 

 tance, indeed the absolute necessity of azotic principles in manures, 

 then, we must not therefore conclude that these principles are the 

 only ones which contribute to fertilize the earth. 



It is unquestionable that the alkaline and earthy salts are further 

 indispensable to the accomplishment of the phenomena of vegeta- 

 tion ; and it is far from being sufficiently shown that the organic 

 principles void of azote play a. merely passive part when added to 

 the soil. But with few exceptions, the lixed salts, water or its ele- 

 ments, and carbon superabound in manure. The element which 

 exists there in smallest proportion is azote, which is the one also that 

 is most apt to be dissipated during the alteration of the bodies that 

 contain it. For these reasons azote is really the element whose 

 presence it is of highest moment to ascertain ; its proportion is that 

 in fact which fixes the comparative value of different manures. 



Since it is by undergoing modification in the course of their de- 

 composition by putrefaction that those azotized substances which are 

 favorable to vegetation are developed in quaternary compounds, it 

 will be readily understood that all things else being equal, a manure 

 which is completely decompoundable into soluble or gaseous products 

 in the course of a single season, will exert in virtue of this alone 

 the whoie of its uselul influence upon the first crop. It is entirely 

 dififereot if the manure decomposes more slowly ; its actioa upon ti'O 



