MANURE. 141 



mon experience tends to the explanation which has been 

 given of the joint action of all their parts. 



197. The source of nitrogen in dung is an interesting ques- 

 tion. It is evident that it must have been introduced into 

 the animal's system by the food, perhaps also by the drink ; 

 for all water contains absorbed air, of course, nitrogen. 

 Hence, the kind of food greatly influences the amount of 

 nitrogen in dung. 



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 nitro 

 gen 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, &c., in 

 a cow fed on hay or on meal, is not very great. A cow was 

 fed six days on meal and water. She consumed in this 

 period, 



Indian meal, 96 lbs., or per day 16 lbs. 

 Hay, 30 " " 5 " 



Water, 330 " " 55 " 



76 Ibs^ 



There were voided during this period 330 lbs. of dung, or 

 55 lbs. daily. She scoured and lost flesh. The evacuation 

 had all the appearance of night soil, and soon evolved a great 

 quantity of ammonia, and though covered in an earthen pot, 

 was soon studded with a crop of exquisitely beautiful fungi. 

 Compared with hay dung, its composition was, 



