BULLETIN OF THE 



SMTOFAMJIi 



No. 143 



Contribution from the Bureau of Soils, Milton Whitney, Chief 

 November 13, 1914. 



PROFESSIONAL PAPER 



THE PRODUCTION AND 

 RIC-SOLXJBLE 



FERTILIZER VALUE OF CIT- 

 IC ACID AND POTASH. 



By Wm. H. Waggaman, 

 Scientist in Investigation of Fertilizer Resources. 



INTRODUCTION. 



The extraction of potash from silicate rocks or the rendering of 

 this alkali soluble in water has been and probably will continue to be 

 for a long time the object of numerous investigations. 



Ross 1 has investigated many of these processes and discussed 

 several in some detail. For convenience he divides them into three 

 classes, as follows: (1) Processes which yield potash as the only 

 product of value; (2) processes which yield potash and some other 

 salable material as a by-product; (3) processes in which two or more 

 operations are combined in one, yielding a fertilizer containing two 

 or more of the constituents, potash, phosphoric acid, and nitrogen. 

 He describes two methods for obtaining potash from feldspar by 

 treating mixtures of that mineral and lime, collecting the potash 

 thus liberated, and using the residue for the manufacture of cement. 

 The potash obtained by these processes, however, is in the form of 

 oxide or hydroxide, and is therefore more valuable for other purposes 

 than for the manufacture of fertilizers. Ross also tried heating 

 together feldspar and lime with the addition of phosphate rock, but 

 found that the latter substance did not enter into the reaction, there 

 being no increase in the quantity of potash thus obtained over that 

 produced by the ignition of feldspar and lime alone. 



The production in a single operation of available phosphoric acid 

 and potash from insoluble minerals, however, presents possibilities 

 which are particularly attractive, and several processes have been 

 devised to accomplish this end. It is the purpose of this paper first 

 to discuss these existing methods and then to describe a process 



1 Jour, of Ind. and Eng. Cheni., 5, No. 9, pp. 725-729 (1913). 

 58060°— 14 



