AGRICULTURAL TEXT-BOOK. 313 



ABC 



Carbonate of lime - - 4.5 6.1 3.6 



Magnesia, - - 0.9 0.2 0.8 



Soda, - - 0.3 0.2 0.8 



Potash, - 0.2 0.1 



The proportion of water in the bones of quadrupeds varies 

 from 7 to 20 per cent according to the age of the animal, and 

 the fat, or oily matter from 13 to 25 per cent. Those of the 

 ox contain 64.5 per cent of earthy matter, and 35.5 per cent of 

 cartilage ; each family differing in this regard. 



680. Bones do not benefit plants under all circumstances, and, 

 as has been stated, the form and mode in which they are ap 

 plied, is of much importance. In Great Britain where they are 

 in especial demand for the turnip crop, it has been the fashion, 

 till of late, merely to grind them in mills built for the purpose ; 

 the bones being of different lengths, from fragments 1 inch long to 

 dust; and sometimes boiled, sometimes unboiled bones were 

 preferred. It is now becoming general there, and in the Uni 

 ted States, to employ them as Superphosphate or Biphosphate 

 of lime, that is, dissolved in Sulphuric acid. This may be done 

 by the Farmer himself procuring the ground bones, and in lead 

 en vessels, boiling in Sulphuric acid diluted with water ; but ac 

 cording to Johnston, the following is the true superphosphate. 

 &quot; When burned bones are reduced to powder, and digested in 

 Sulphuric acid, diluted with once or twice its weight of water, 

 the acid combines with a portion of the lime, and forms sulphate 

 of lime (plaster) while the remainder of the lime and the whole 

 of the phosphoric acid are dissolved. The solution, therefore, 

 contains an add phosphate of lime, or one in which the phos 

 phoric acid exists in much larger quantity than in the earth of 

 bones. The true bi-phosphate when free from water consists of 

 71 J phosphoric acid, and 2S|- of lime.&quot; In a manufactured 

 state, however, it is probably never found thus pure ; and great 

 complaints have, at times, been made that the manufacturers mix 



