126 



PHOSPHATIC MANURES 



obtained by comparing the densities of the phospho- 

 molybdate precipitates obtained in each case by apply- 

 ing the usual test for phosphates to the solutions. 



(J?) About I gram each of powdered bone ash, 

 ignited tricalcium phosphate prepared from 108 {a), and 

 the precipitated dicalcium phosphate (108 {by) are mixed 

 with 100 c.c. of water, and through each suspension is 

 passed carbon dioxide for about ten minutes. After 

 standing for a further fifteen minutes the liquids are 

 filtered and the various filtrates tested with ammonium- 

 molybdate solution. From the appearance of the 

 yellow precipitates may be gauged the amount of 

 phosphate dissolved in each case. 



Bones and Bone Manures. 



The chief constituents of bones are tricalcium phosphate, 

 calcium carbonate, and organic matter. The latter, which may be 

 present to the extent of 30 per cent., is composed chiefly of 

 nitrogenous material and fat. Nitrogen may be present to the 

 extent of 3 to 4 per cent., and exists chiefly as bone collagen or 

 ossein. The following are the most important bone compounds 

 used as manures : — 



