174 ON MANURE. 



cow upon hay and turnips, and we obtain a manure containing 

 all the mineral constituents of grass and of turnips ; this manure 

 ought to be preferred, as being more suitable for turnips than 

 that procured from any other source. The dung of pigeons con- 

 tains the mineral ingredient of the cereal grains ; that of the 

 rabbit, the constituents of culinary vegetables ; the liquid and 

 solid excrements of man contain in very great quantity the 

 mineral substances of all seeds. 



According to the above view, a knowledge of the constituents 

 of the ashes of food and of fodder, gives us an exact indication 

 of the ingredients of the soil contained in the liquid and solid ex- 

 crements of men and of animals. 



If we know the quantity of the food, and the composition of its 

 ashes, we know also with certainty how much soluble salts will 

 be contained in the urine, and how much of the insoluble salts 

 will exist in the faeces. It would, therefore, be superfluous and 

 useless to state here a greater number of analyses of excrements, 

 because these analyses must differ from each other, quite as 

 much as the variation in composition of the ashes of the food on 

 which the animal was fed. 



Common stable manure is a mixture?, of solid excrements with 

 urine, which gradually enters into putrefaction in the dunghill. 

 In consequence of the putrefaction of the urine, all the urea con- 

 tained in it is converted into volatile carbonate of ammonia. A 

 large portion of the organic ingredients of the manure enter into 

 decay and assume a gaseous condition, by the action of the air, 

 with the continued evolution of heat. The weight of these 

 ingredients diminishes, while the relative proportion of the fixed 

 mineral substances increases. If all the decaying matters 

 entered into union with oxygen, the result of course would be, 

 that those not susceptible of decay, or, in other words, the ashes, 

 would alone remain behind. The following analysis will illus. 

 trate the meaning of this remark : — 



100 parts fresh Cow-dung — 



Water - - 1 - - - S5900 



Combustible substances - 12* 



Ashes 1410 ° 



2,352 ) 

 T748 > 



100 000 



