The Phosphates of America. 115 



was drawn as in the last experiment, it had already commenced to 

 " set," and the result of the analysis was : 



Total phosphoric anhydride soluble in hydrochloric acid. ... 18.97 

 Of which there was found to be 



Water-soluble phosphoric adhydride 16.30 



Citrate-soluble " " 18.10 



At the end of thirty-six hours after mixing, it was dry enough to 

 be dug out of the " den " and was in a very porous and friable state, 

 the analysis at this time showing it to contain : 



Total phosphoric anhydride soluble in hydrochloric acid. ... 19.19 

 Of which there was found to be 



Water-soluble phosphoric anhydride 16.17 



Citrate-soluble " " 18.53 



The increase in the last figure was due to decrease in moisture. 



In order to test the question of the advisability or otherwise of 

 using calcined phosphates from Florida, made by the prevailing 

 method of firing the material in heaps, a third experiment was 

 performed at the same works. Before treatment with acid the 

 finely comminuted material (70-mesh) was analyzed with the fol- 

 lowing result : 



Phosphate of lime 77.18 (equal to 35.40 P S O 5 ) 



Carbonate of lime 3 . 64 



Quick-lime , 4.65 



Oxides of alumina and iron (combined) 7 . 53 

 Moisture, insoluble, and undetermined 7 . 00 



100 



After being worKed. up with 92 pounds of 55 B. sulphuric acid 

 it was dropped into the " den " as usual, and sampled and analyzed 

 at the end of an hour, as in the other cases. It was still quite wet 

 and yielded : 



Total phosphoric anhydride soluble in hydrochloric acid. ... 18.72 

 Of which there was found to be 



Water-soluble phosphoric anhydride 15 . 54 



Citrate-soluble " " 16.79 



It was removed from the " den " on the eighth day after its manu- 

 facture, in a very damp and unsatisfactory condition, quite unfit 

 to pass through the pulverizer or to be put into bags. It yielded 

 on analysis : 



