PERCENTAGE OF FOOD IN EXCRETA. 11 



the organic matter, 87.3 of the nitrogen, and 98.7 of 

 mineral matter ; while Warington, in summarising his 

 results, points out that, with fattening oxen and sheep 

 and with horses, more than 95 per cent of the nitrogen 

 and 96 per cent or more of the ash constituents are 

 voided in the manure. The pig retains a larger pro- 

 portion of the nitrogen about 85 per cent appearing 

 in the manure while in the milking cow only about 

 75 per cent are returned in the excrements. Gener- 

 ally speaking, we may say that the nitrogen originally 

 present in the food suffers very little loss in passing 

 through the animal system, and that practically speak- 

 ing the ash constituents suffer no loss whatever. 



As to the distribution of the manurial ingredients, 

 much will depend on the nature of the food. Almost 

 invariably more than a half of the total nitrogen ex- 

 creted will be found in the urine, in many cases very 

 much more. 1 Of the mineral constituents, about a 

 third on the average may be said to be excreted in 

 the urine. Of this mineral matter it may be noted 

 that nearly all the alkalies (potash and soda), or about 

 98 per cent, are found in the urine. Of phosphoric 

 acid and lime, on the other hand, there are the merest 



1 Warington puts this matter admirably in the following words : 

 " If the food is nitrogenous and easily digested, the nitrogen in the 

 urine will greatly preponderate ; if, on the other hand, the food is 

 one imperfectly digested, the nitrogen in the solid excrement may 

 form the larger quantity. When poor hay is given to horses, the 

 nitrogen in the solid excrement will exceed that contained in the 

 urine. On the other hand, corn, cake, and roots yield a large ex- 

 cess of nitrogen in the urine " (Chemistry of the Farm, p. 137). 



