92 ' EXCREMENTS AND URINE. 



of nitrogen, and the greatest quantity of water, 

 amongst the manures of which we have spoken. 

 On this account, they pass but slowly into putrefac- 

 tion, and are less heated by putting in heaps; for 

 heating is exclusively a result of the putrefactive fer- 

 mentation (which, like the process of digestion, is 

 also a slow combustion), and is throughout most 

 closely governed by this process. In addition to 

 this, the mass of these excrements does not crumble 

 by lying or desiccation, but becomes saponaceous 

 and compact; for which reason, its distribution in 

 the soil, as also its decomposition and liquefaction, 

 is rendered more difficult. The slow but persistent 

 action of this manure is thus explained at once. 



The excrements of horses are richer in nitrogen, 

 and less watery, than the preceding ; they have a 

 somewhat denser texture, and cohere but loosely. 

 For this reason they are readily distributed, and pass 

 quickly (and accordingly with a greater evolution of 

 heat) into decay. In consequence of this facility of 

 decomposition, the nutritious elements they contain 

 can be more speedily appropriated and digested by 

 plants ; hence their operation is apparent immedi- 

 ately after their application to the soil, but from this 

 circumstance terminates more quickly than that of 

 manures whose action is more tardy. 



The excrements of sheep contain still more nitro- 

 gen and still less water than those of horses. For 

 this reason they are tolerably easy of decomposition, 

 although possessing: a closer and more compact tex- 



