110 



The Phosphates of America. 



Molecular Weights. 



78 98 



CaF 2 + H 8 SO 4 CaSO 4 + 2HF 



1 molecule of + 1 molecule of = 1 molecule of + 2 molecules of 



calcium fluor- m o n o h ydrate gypsum h y d r o fl u o ric 



ide sulphuric acid acid. 



If three hundred and ten parts of tribasic phosphate of lime 

 require one hundred and ninety-six parts of the pure monohydrate 

 of sulphuric anhydride (H 2 SO 4 ) for its transformation into mono- 

 calcic or acid-phosphate, it follows that 1 part will require .632 

 parts of the acid. 



Assuming the chamber acid we are called upon to use to be of 

 50 B. strength, we refer to our table and find that it contains 

 62.47 per cent, of pure H 2 SO 4 . The quantity of it to be taken as 

 an equivalent of .632 parts of the latter, therefore, is found by the 

 equation: 62.47 : 100 :: 0.632 x = 1.012 parts, and this is the 

 method of calculation we must observe for all the bodies shown to 

 exist in our sample of phosphate. 



TABLE SHOWING THE QUANTITY OP CHAMBER SULPHURIC ACID OF VARIOUS STRENGTHS 

 -EXPRESSED IN POUNDS-REQUIRED IN THE MANUFACTURE OF SUPERPHOSPHATE 

 FROM NATURAL PHOSPHATES IN ORDER TO PRODUCE ACID-PHOSPHATE. 



With a proper application of the data thus furnished there 

 should be no difficulty in dealing with any phosphatic material of 

 which the composition is accurately known, and it is only neces- 

 sary, in proof of this, to give one more illustration. 



Returning to the phosphate we have already used, but assum- 



