66 Fertilizers 



offered on the market. Bone of the following analyses 

 can usually be secured : 



GRADES OP BONE 



Bone tankage. 



Tankage is made from the residue remaining after 

 boiling cattle heads, feet, clippings, cartilage and other 

 refuse animal matter. It may be classed with boiled 

 bone in reference to the quality of its phosphoric acid. 

 Its agricultural value is further modified by the fineness 

 of division; it is frequently substituted for bone in the 

 manufacture of fertilizers, where phosphate derived from 

 bone is regarded as an important constituent of the mix- 

 ture or brand. 



While the market shows an increased tendency to limit 

 such products, six distinct grades still exist as shown 

 below : 



GRADES OP BONE TANKAGE 



Percentage Percentage 



Bone Phosphate of Lime Phosphoric Acid 



18 to 19.0 equivalent to 40 



16.0 equivalent to 35 



13.5 equivalent to 30 



11.5 equivalent to 25 



9.0 equivalent to 20 



7.0 equivalent to 15 



It will be observed that certain grades of tankage ap- 

 proach the composition of bone in their content of phos- 



