MANURES. 153 



lime. Tlie_y arc the receptacles wliich collect nearly 

 all of the phosphates in crops which are fed to ani- 

 mals, and are not returned in their excrements. For 

 the grain, etc., sent out of the country, there is no 

 way to be repaid except by the importation of this 

 material; but nearly all that is fed to animals may, 

 if a proper use be made of their excrement, and of 

 their bones after death, be returned to the soil. With 

 the treatment of animal excrements we are already 

 familiar, and we will now turn our attention to the 

 subject of 



BONES. 



Bones consist, when dried, of about one-third or- 

 ganic matter, and two-thirds earthy matter. 



The organic matter consists chiefly of gelatine — a 

 compound containing nitrogen. 



The earthy part is Q)i\\Q^y[ phosphate of lime. 



Hence we see that bones are excellent, both as or- 

 ganic and as mineral manure. The organic part, con- 

 taining nitrogen, forms ammonia^ and the inorganic 

 part supplies the much -needed phosphoric acid to the 

 Boil. 



Liebig says that, as a producer of ammonia, 100 

 lbs. of dry bones are ecpiivalent to 250 lbs. of liuman 

 urine. 



Bones are applied to the soil in almost every con- 

 ceivable form. Whole hones are often used in very 

 large quantities ; their action, however, is extremely 

 slow, and it is never advisable to use them in thia 

 form. 



