112 THE CHEMISTRY OF THE FARM. 



the food which is stored up in the body of a fattening 

 animal is in all cases very small. In the case of each 

 animal mentioned in the above tables more than 95 per 

 cent, of the ash constituents of the food find their way 

 into the manure. With oxen and sheep more than 95 

 per cent, of the nitrogen of the food are likewise thus 

 voided. The pig is seen to retain the largest proportion 

 of the nitrogen of its food ; this is clearly owing to the 

 greater proportion of increase which the pig produces for 

 a given weight of food consumed. 



The amount of nitrogen voided in the urine is seen to 

 be three or four times the quantity contained in the solid 

 excrement. This relation will vary greatly according to 

 the character of the diet. If the food is nitrogenous, and 

 easily digested, the nitrogen in the urine will greatly pre- 

 ponderate ; if, on the other hand, the food is one imper- 

 fectly digested, the nitrogen in the solid excrement may 

 form the larger quantity. When ordinary hay is the diet, 

 the nitrogen in the solid excrement will generally some- 

 what exceed that contained in the urine ; with a straw 

 diet the excess in the solid excrement will be much 

 greater. On the other hand, corn and cake, and especially 

 roots, yield a large excess of nitrogen in the urine. 



The ash constituents are very differently distributed in 

 the solid excrement and urine ; in the former the lime, 

 magnesia, and phosphoric acid are chiefly found, while 

 the latter contains nearly all the potash. With sheep fed 

 on hay, about 95 per cent, of the lime contained in the 

 food, 70 per cent, of the magnesia, and 83 per cent, of the 

 phosphoric acid were found in the solid excrement, but 

 only 3 per cent, of the potash. 



A fair idea of the general composition of the solid excre- 



