Sources of Phosphoric Acid and Potash 9 



is the air, through the agency of leguminous plants, the 

 varieties and uses of which will be discussed further on. 



SOURCES OF PHOSPHORIC ACID 



Previous to the discovery of the beds of phosphate of 

 lime on the coast of South Carolina by Dr. N. A. Pratt, 

 in 1867, the only commercial source of phosphoric acid 

 was animal bone. At present, the principal deposits of 

 phosphate of lime, from which the commercial supply of 

 phosphoric acid is obtained, are found on the coast of 

 South Carolina, in southern Florida and Tennessee. 

 These, pulverized to the condition of an impalpable pow- 

 der and treated with sulphuric acid, yield the available 

 phosphoric acid so extensively used in the Atlantic and 

 Gulf States. 



COMMERCIAL SOURCES OF POTASH 



The Stassfurt mines in northern Germany now sup- 

 ply practically all of the potash salts used in compound- 

 ing commercial fertilizers. Of these: 



Muriate of potash contains 48 to 52 per cent of actual 

 potash, and constitutes the principal source of supplj^ in 

 manipulated commercial fertilizers. 



Kainit, a natural product of the same mines, is 

 extensively used in the southern states. This contains 

 from 12 J to 13 per cent of actual potash, in combina- 

 tion with 23 to 26 per cent of sulphate of potash, about 

 35 per cent of common salt (chloride of sodium), some 

 sulphate and chloride of magnesia and a small amount 

 of gypsum. 



