118 MANUFACTURE OF FERTILIZING MATERIALS 



hold true when sodium chloride is used, bub 

 with a more limited variation in the proportion 

 of the reagents which may be taken. Thus, 

 a hardened mass is obtained when 1 part of 

 feldspar is ignited to 1050 C., with 1 part of 

 calcium carbonate and 0.25 part of sodium chlo- 

 ride, but if the proportion of calcium carbonate 

 is doubled the mass remains in a powdered form. 

 When calcium chloride is used, the mass does 

 not harden on ignition, even with 1 part of cal- 

 cium carbonate. 



On account of its simplicity, the method of 

 decomposing feldspar by heating with calcium 

 carbonate and with calcium chloride (or sodium 

 chloride) could undoubtedly be carried out on 

 a large scale without involving any serious me- 

 chanical difficulty, and the method would thus 

 be a practical one providing the value of the 

 products obtained would compensate for the 

 expense involved. Although pure feldspar may 

 be obtained which contains upward of 15 per 

 cent potash, the average grade of feldspar which 

 could be mined on a large scale would undoubtedly 

 contain less than 10 per cent. If potash be quoted 

 at sixty-six cents a unit, then potash in a ton of 

 feldspar containing even 10 per cent of this 

 constituent would be worth only $6.60 when 

 converted into the soluble form. It is then evi- 

 dent that the value of the potash alone will 

 not compensate for its extraction, or by any 

 modification of it for which patents have been 



