114 The Phosphates of America. 



The following experiments were made with Florida phosphate 

 containing as high as eight per cent, of iron and alumina. After 

 having been tried in several factories and pronounced worthless for 

 the purpose, they w r ere finally made into superphosphates of excep- 

 tionally good quality. 



The composition of the material was : 



Phosphate of lime. 81.10(e.qual to 37.20 P 3 O 6 ) 



Carbonate of lime 3.70 



Oxides of iron and alumina (combined) 7 . 90 



Moisture, insoluble, and undetermined 7 . 30 



100 



One hundred pounds of it were treated with 94 pounds of 55 B. 

 chamber acid, and one hour after the " super" had dropped into the 

 " den " a sample was drawn from various points, mixed, analyzed 

 and found to contain : 



Total phosphoric anhydride soluble in hydrochloric acid 20.01 



Of which there was found to be 



Water-soluble phosphoric anhydride 15.90 



Citrate-soluble " " 16.30 



At the end of ten days this " super " was still in the " den " 

 and in a very wet and unmanageable condition. Sampling and 

 analyses were repeated, and it was now found to contain : 



Total phosphoric anhydride soluble in hydrochloric acid. . . . 19.96 

 Of which there was found to be 



Water-soluble phosphoric anhydride 15. 10 



Citrate-soluble t " " 17.01 



Another batch was made with the same lot of phosphate after 

 adding to it eight per cent, by weight of very finely powdered chalk. 

 Upon analyses before treatment with acid it was now shown to 

 contain : 



Phosphate of lime 75.03 (equal to 34.40 P 2 O 5 ) 



Carbonate of lime 10.72 



Oxides of iron and alumina (combined): 7 . 27 



Moisture, insoluble, and undetermined 6 . 98 



100 



One hundred pounds were passed through a 70-mesh screen and 

 then worked up with 92 pounds of 55 B. chamber acid as before, and 

 dropped into the "den." At the end of an hour, when the sample 



