DAVIS] STUDIES OF COMMERIAL FERTILIZERS 127 



If a ton of mixture containing two per cent of nitrogen is wanted 

 the amount of nitrate of soda needed to furnish this amount of 

 nitrogen (two per cent) may be found as follows: A ton (2000 

 pounds) containing two per cent of nitrogen will have two per 

 cent of 2000 (2000 X .02 = 40), or 40 pounds of nitrogen. Since 

 nitrate of soda contains 16 per cent, one pound of nitrate of soda 

 will contain .16 of a pound of nitrogen (ix.16 = .16). Therefore, 

 as many pounds of nitrate of soda will be required to furnish 

 40 pounds of nitrogen as .16 is contained times in 40 (40 ^ .16 = 

 250), or 250 pounds. 



Similar calculations can be made of phosphoric acid, and of 

 potash by substituting 14 per cent for phosphoric acid and 50 

 per cent for potash. 



Suppose a ton of a 4-8-3 fertilizer is to be made. How much 

 nitrate of soda, acid phosphate, and muriate of potash will be 

 needed? First, find the number of pounds of nitrogen, phos- 

 phoric acid and potash in a ton of 4-8-3 fertilizer : 

 2000 X .04 = 80, or 80 pounds of nitrogen 

 2000 X .08 = 160, or 160 pounds of phosphoric acid 

 2000 X .03 = 60, or 60 pounds of potash 



Next find the amounts of nitrate of soda, acid phosphate and 

 muriate of potash necessary to furnish the required number of 

 pounds of nitrogen, phosphoric acid and potash: 



80 ^- .16 = 500, or 500 pounds of nitrate of soda needed to furnish 80 

 pounds of nitrogen. 



160 -i- .14 = II 42. 8, or II 42. 8 pounds of acid phosphate needed to furnish 

 160 pounds of phosphoric acid. 



60 -^ .50 = 120, or 120 pounds of muriate of potash needed to furnish 

 60 pounds of potash. 



The cost of such a mixture may be easily found by using the 

 following (average market price for 1913) : Nitrate of soda $57.50 

 per ton; acid phosphate (14 per cent phosphoric acid) $16.00 

 per ton; muriate of potash $42.00 per ton. Find value of each 

 material per pound and multiply by total number of pounds 

 desired : 



At $57.50 per ton, one pound of nitrate of soda will cost 2.375 

 cents (57.50 x 100 -^ 2000 = 2.375). 500 pounds will cost $11,875 

 (500X. 02375 = 11.875). 



At $16 per ton, one pound of acid phosphate will cost .8 of a 

 cent per pound (16 x 100 -^ 2000 = .8). 160 pounds will cost 

 $12.80 (160 X .008 = 12.80). 



