156 Agricultural Chemistry. 



nection with manure or on soils rich in organic matter. The 

 reason usually assigned for the necessity of incorporating this 

 material with organic matter, is that the latter in its decay, lib- 

 erates acids, which attack the phosphate and render it more 

 available. 



Bone meal or ground bone is a product of the packing houses, 

 glue factories and soap works, the raw material being the bones 

 of farm animals. These are either ground directly (raw bones) 

 or after having been steamed and dried (steamed bones). This 

 latter process removes nearly all the fat, tendons and the nitro- 

 genous tissue adhering to the bones. The steamed bone which 

 comes from the glue or soap factories, is, as a result of the process 

 of steaming, poorer in nitrogen and richer in phosphoric acid than 

 the raw bones. Raw bone contains about 2.5 per cent of nitrogen 

 and 25 per cent of phosphoric acid, while the average figures for 

 steamed bone are 0.5 per cent and 29 per cent of nitrogen and 

 phosphoric acid, respectively. The effect of bone meal on crops 

 is largely dependent on its degree of fineness, since it will be de- 

 composed more quickly in the soil the finer it is ground. Again, 

 the raw bone meal decomposes more slowly, due to the presence 

 of fat which retards such processes ; while the steamed bones not 

 only allow a much more perfect pulverization, but also a more 

 rapid decomposition in the soil, and consequently are considered 

 of somewhat higher availability. Both materials contain th^ 

 phosphoric acid in the form of insoluble phosphate of lime.' 



Bone ash is incinerated cattle bones, imported from South 

 America; the nitrogenous constituents of the bones have been 

 lost in the process of burning. It consists chiefly of the insol- 

 uble phosphate of lime and contains from 30 to 35 per cent of 

 phosphoric acid. Bone black or animal charcoal is a refuse prod- 

 uct from sugar refineries and contains about 33 per cent of phos- 

 phoric acid. 



Dissolved bone is made by treating raw bone with sulphuric 

 acid. By this process the insoluble phosphate is converted into 

 soluble phosphate and the organic nitrogenous material into 



