MANURE. 137 



The evacuated dung contained 3*03 nitrogen, 

 The hay originally contained 1*67 " 



1-36 



Hence, nearly double the amount of nitrogen 

 contained in the hay eaten, has been voided. Its 

 source must be looked for in the potatoes, and in the 

 atmospheric air, absorbed by the water which was 

 drank. But it is evident from these facts, that dung 

 owes not its value to the nitrogen only, of hay ; nor 

 will the effects be different, if the salts only of 

 equivalent portions of dung and hay be taken. 



198. If a cow assimilated all the nitrogen of her 

 hay, 25 lbs. of hay would increase her weight daily, 

 by about 8 lbs. ; but no one expects such a result, 

 and the balance of the nitrogen goes off in milk, or 

 in liquid excretions. Hence, a milch cow fats not. 

 So long as a greater part of the nitrogen is voided 

 by milk or otherwise, a cow fats not. If she is not 

 parting with nitrogen in milk, a greater portion 

 goes off in dung. Hence, a common observation, 

 that the manure of fattening cattle is richer than 

 that of milch cows, or of cattle not fattening. 



199. The difference in the quantity of bile, 

 slime, he, in a cow fed on hay or on meal, is not 



12* 



