FERTILIZERS. 57 



misnomer ; for there cannot be such a thing as 4 soluble 

 bone phosphate, for bone phosphate is always in an insolu- 

 ble condition, and, when it is made soluble, it is no longer 

 a bone phosphate." The term " available " phosphoric 

 acid is sometimes used. This includes both the soluble 

 and the reverted, as the latter soon becomes soluble in the 

 soil. 



BONES, AND WHERE THEY COME FROM. 



The bones of land animals are composed of the follow- 

 ing ingredients : 



Gelatine, fat, and water . . . . .48 



Phosphate of lime, with a little magnesia . . .46 



Carbonate of lime ' .04 



Potash and soda 02 



100 



The gelatine contains from three to five per cent of 

 nitrogen, and the phosphate of lime (or bone phosphate) 

 from eighteen to twenty-three per cent of phosphoric acid. 



Bones are brought to the fertilizer market as the waste 

 of the slaughter-houses or butcher-shops, from the plains 

 of South America or the prairies of the West, or a& 

 " char," or burnt bone, that has been used principally as 

 a purifier in the process of manufacturing sugar. This 

 latter is sometimes counterfeited by mixing lampblack 

 with mineral phosphates. Where they have been exposed 

 to the action of the elements, bones are found to have lost 

 more or less of their gelatine, and hence are not so rich 

 in nitrogen. The ways of preparing bone for plant-food 

 are numerous: by one class of processes the gelatine is 

 saved, and by the other lost. By burning bones either in 

 closed vessels which produces the bone-black, or " char " 

 or in open fires, all the animal matter, which includes 

 the gelatine and oil, is consumed, and we have only phos- 



