272 PHYSIOLOGY AT THE FARM. 



gases, and at last loses its smell. By this fermentation a large 

 proportion of valuable matter is allowed to escape into the air. 

 The most economical method of obviating this loss is to mix it 

 with earth rich in vegetable matter, with partially-dried peat, 

 with sawdust, or with some other readily accessible absorbent 

 substance.* 



The excrements of carnivorous animals, as of the dog fed on 

 flesh, contain a substance allied to excretine, but not identical 

 with it ; they contain no excretine, but they contain butyric 

 acid, which is not found in the excrement of man. 



The excrements of herbivorous animals, as the horse, ox, 

 sheep, and those of the dog fed on bread, contain no excretine, 

 no butyric acid, and no cholesterine. 



The following table, after Boussingault, shows the compara- 

 tive ultimate composition of horse-dung and cow-dung : 



Horse. Cow. 



Carbon, .... 38.7 42.8 



Hydrogen, . . . . 5.1 5.2 



Oxygen, .... 37.7 37.7 



Nitrogen, . . . . 2.2 2.3 



Ash, . . . . 16.3 12.0 



100.0 100.0 



Water, . . . . 300.0 566.0 



400.0 666.0 



Analysis of ash of horse-dung from Hemming's tables. 

 Dung dried at 212 Fahr. : 



Organic matter, . . . . . 86.4 



Ash, .... . 13.6 



100.0 



Sand and silica, . . . . . 62.4 



Potash, . . . . . . 11.3 



Soda, ...... 2.0 



* Johnston, ' Agricultural Chemistry, ' pp. 682, 683. 



