Food for 

 Plants 



We make a similar calculation for sulphate of ammonia, 

 as follows: 100 pounds of sulphate of ammonia contain 20.50 

 per cent, of Nitrogen. Therefore, i pound of sulphate of 

 ammonia contains the one-hundredth part of 20.50, or .2050, 

 and we have 10,000-:-'. 20 5 0=48. 7 pounds, or we simply 

 take 50 pounds of sulphate of ammonia, which contain 10.25 

 pounds of Nitrogen. Like calculations for all the raw mate- 

 rials are made, and, after estimating the required quantities 

 for all the constituents, we have : 



We have the required percentages of Nitrogen, available 

 phosphoric acid, and potash, but instead of i ton of 2,000 

 pounds we have only 1,2731/2 pounds of materials. We may 

 add T2.i l / 2 pounds of land plaster, peat, coal ashes, or loam 

 to make up the ton. 



This formula illustrates the question often raised by 

 farmers: "Why does the sum of the fertilizing constituents 

 in the analysis of a fertilizer amount to so much less than the 

 total weight of the fertilizer, and what is used by the manu- 

 facturer to make up the difference?" We find that when the 

 percentages of Nitrogen, total phosphoric acid, and potash 

 are added together, the sum of their weights range between 

 1 6 and 30 per cent, of the total weight, and that in each ton 



