Purchase of Fertilizers 163 



tain from 95 to 97 per cent pure nitrate, it means that it is 

 95 to 97 per cent pure, or that 3 to 5 per cent of the sub- 

 stance consists of impurities; it is not absolutely pure 

 nitrate of soda. Hence, the minimum percentage of 

 nitrogen guaranteed is 15.65 per cent, or 95 per cent of 

 16.47, the per cent or pounds in each hundred of nitrogen 

 contained in pure nitrate of soda. When muriate of potash 

 is guaranteed 80 per cent muriate, it means that 80 per 

 cent of the salt consists of pure muriate of potash, and 

 because pure muriate of potash contains 63 per cent of 

 actual potash, or potassium oxide, the actual content of 

 potash is derived by multiplying the 63 per cent, which 

 the pure salt contains, by 80 per cent, and the result, 50.5 

 per cent, represents the amount of actual potash guaran- 

 teed. Sulfate of potash, high-grade, is usually guaranteed 

 to be 98 per cent pure, and since pure sulfate of potash 

 contains 54 per cent of actual potash, the content of actual 

 potash, or potassium oxide, guaranteed is found by mul- 

 tiplying the 54 per cent by 98 per cent. The following 

 illustrations show the two methods of stating the guar- 

 antees of raw materials and of mixed fertilizers : 



Raw materials. 



GUARANTEE ON BASIS OP PURITY 



Nitrate of soda . . . 98%, or containing 98% pure nitrate 



Muriate of potash . . 80%, or containing 80% pure muriate 



Sulfate of potash . . 98%, or containing 98% pure sulfate 



Kainit ...... 25%, or containing 25% pure sulfate 



GUARANTEE ON BASIS OF ACTUAL CONSTITUENTS 



Nitrate of soda, total nitrogen 16.00% 



Muriate of potash, actual potash 50.50% 



Sulfate of potash, actual potash 53.00% 



