BULLETIN 143, U. S. DEPARTMENT OF AGRICULTURE. 



Table IV, 



-Solubility of feldspar in %oater and in water saturated with CO*, a$ 

 determined by various investigators. 



Investigator. 



Amount 

 of feld- 

 spar used. 



Amount 



of water 



used. 



Time of 

 contact. 



Method of treatment. 



Amount 

 of K2O dis- 

 solved from 



feldspar. 



Amount 

 of K 2 in 

 solutions. 





Grams. 

 3,000 



2,000 

 2 



2 

 25 



25 



Grams. 

 5,000 



(C0 2 ) 3,000 

 1,000 



(COs) 1,000 



100 



100 



192 hours.. 

 240 hours . 



Triturated in re- 

 volving cylinder. 

 do. . 



Per cent. 

 0.420 



.013 

 .085 



.125 

 1 .100 



1 1.280 



P. p. m. 

 2,520.0 



90.0 



Do 



Cameron and Bell. . . 

 Do 



14 months. 

 ...do 



Allowed to stand in 

 contact with water. 



1.7 

 2.5 



Cushman and Hub- 

 bard. 

 Do 



Not given. 

 ...do 



Mineral ground while 



dry. 

 Mineral ground wet. 



1 250.0 

 1 3,200.0 





1 Total residue. 



In the experiments for comparing the solubility of the potash in 

 33SB with that of feldspar, a large quantity of the slag product was 

 first prepared and ground to pass a 200-mesh screen. On analysis 

 this material showed the following composition : 



Per cent. 



K 2 citric soluble 5. 14 



KoO total 5.43 



P2O5 citric soluble 6.32 



P2O5 total 6.31 



Two samples of this slag of 25 grams and 0.25 gram, respectively, 

 and the same quantities in weight of feldspar (ground equally fine) 

 were placed in platinum-lined brass cylinders, 100 cubic centimeters 

 of water were added to each and carbon dioxide under an average 

 pressure of l-£ atmospheres was passed through the solutions for one 

 week. At the end of that time the amount of potash dissolved from 

 each sample was determined' by analysis of the' solutions. The re- 

 sults of these analyses are given in Table V. 



Table V. — Solubility of the potash in the slag product (33SB) in ivater 

 saturated with carbon dioxide, compared with that of the potash in 

 feldspar. 



Material used. 



Amount of 



Amount of 



material 



water 



used. 



employed. 



Grams. 



C.c. 



25.00 



100 



.25 



100 



25.00 



100 



.25 



100 



Potash dissolved. 



Potash in 

 solution. 



Percentage 

 of total 



potash in 

 sample. 



Feldspar... 



Do 



Slag (33SB) 



Do 



P. p. m. 



127.5 



4.7 



150.0 



11.9 



0.35 

 1.37 

 1.11 



8.76 



