G. S. Robertson 



17 



Five grams of each of the phosphates were calcined in a Fletcher 

 muffle furnace in order to determine what, if any, changes were produced 

 by heating. 



Makatea Island Phosphate. 



The results with Makatea Island phosphate are given in the following 

 tables. 



The result of thirty determinations shows an average relationship 

 P2O5 : CaO of 1 : 1-38 for the phosphoric acid and hme dissolving out 

 in the citric acid solutions, and in hydrochloric acid. This ratio is 

 quite different from the relationship in tricalcium phosphate 1 : 1-18, 

 or in apatite 1 : 1-31, and agrees with the ratio of phosphoric acid to 

 lime in a phosphate with the formula 2Ca3P208 . CaO. 



Joum. of Agric. Sci. viii 2 



