90 EXCREMENTS AND URINE. 



4. Phosphoric acid in herbivorous animals passes 

 from the food into the solid excrements, inasmuch 

 as it unites with lime and becomes thereby insolu- 

 ble. After nitrogen, it must be regarded as their 

 most important and valuable ingredient. In mixed 

 nourishment and animal diet, a part of this acid es- 

 capes also by the urine ; for this secretion in men 

 and swine contains phosphoric acid in the form of 

 soluble salts. 



5. The remaining insoluble mineral constituents 

 of animal provender, Zzme, magnesia, and silica, jaxe 

 in like manner transferred for the most part into the 

 solid excrement. They must be regarded as the 

 least valuable constituents of manure. 



The solid excrements of herbivorous animals are 

 therefore, comparatively speaking, rich in humus-form^ 

 ing (organic) and seed-forming substances (phosphoric 

 acid, lime, and magnesia), but poor in forcing and 

 leaf-forming substances ; they operate, moreover, but 

 slowly, because the nitrogen they contain passes into 

 putrefaction, that is, is converted into ammonia, but 

 slowly. Hence the solid excrements alone, except, 

 perhaps, on exceedingly rich soils, are incapable of 

 calling forth a luxuriant growth ; they cannot be 

 deemed a " complete manure," because, in addition 

 to the requisite quantity of easily soluble azotized 

 substances, they are also destitute of the soluble 

 mineral ingredients. 



The urine of herbivorous animals is, comparatively 

 speaking, rich in substances forming stalks and leaves 



