122 MANUFACTURE OF FERTILIZING MATERIALS 



experiments already referred to, and experi- 

 ments are now being taken on a large scale to 

 compare the practicability of this procedure with 

 the simple ignition of feldspar and lime alone. 



According to census reports of 1910, the Port- 

 land cement manufacture in the United States 

 during the year 1909, amounted to 65,000,000 

 barrels, or 13,000,030 tons, valued at approxi- 

 mately $53,000,000. The maximum quantity of 

 potash which it would be possible to obtain by 

 the use of feldspar in the manufacture of this 

 quantity of cement can be calculated if the potash 

 content of the feldspar is known. This varies 

 from about 16 per cent down to less than 8 per 

 cent, but if 8 per cent be taken as the average 

 percentage of potash in commercial feldspar, then 

 1 part of feldspar combined with 3 parts of cal- 

 cium carbonate, equal to 1.68 parts of calcium 

 oxide, would yield 0.08 part of potash and 2.6 

 parts of cement. Therefore, 13,000,000 tons of 

 cement would produce 400,000 tons of potash. 

 Again, quoting potash at 66 cents per unit, this 

 would have a value of $26,400,000, which is 

 three times the value of the potash salts used in 

 this country during the year referred to, and 

 about twice the value of the imports for 1911. 

 Whether or not this would cover the cost of the 

 feldspar, its transportation, and the expense inci- 

 dent to the recovery of the potash, can only be 

 determined by experimentation on a large scale; 

 but the probability that potash salts can thus be 



