24 
Journal of Agricultural Research 
Vol. VIII, No. i 
SOLUBILITY OF THE POTASSIUM IN ORTHOCLASE AS AFFECTED BY 
CALCIUM HYDRATE AND CALCIUM SULPHATE 
Measurements relating to the effect of calcium hydrate on the solu¬ 
bility of potash in orthoclase, carried out in a similar manner to those 
with pegmatite, are given in Table III. Here, again, there is no indica¬ 
tion that the presence of calcium affects the solubility of the potash. 
Table; III. —Effect of solutions of calcium hydrate on the solubility of the potash in 
orthoclase 
Solution No. 
Calcium 
oxid in 
ioo c. c. of 
solution. 
Potassium 
oxid in 
solution. 
I.. 
Gm. 
o. oo 
. 0103 
. 0207 
. 0414 
. 0621 
. 0828 
• 1035 
a . 1242 
P . p. m . 
IO. 8 
8.6 
12. O 
8. 2 
9 . I 
12, 6 
12. I 
9.6 
2. 
*2. 
o 
A . 
<. 
6. 
7 .. 
8. 
a Solid phase present. 
The results of similar determinations of the solubility of the potassium 
in orthoclase in the presence of solutions of calcium sulphate of vary¬ 
ing concentration are presented in Table IV. A different sample of 
orthoclase was used in this case from that employed in the calcium 
hydroxid series, which accounts for the difference in solubility of the 
feldspar in distilled water in the* two series. As before, there is no 
indication that potash is being replaced by lime. On the other hand, 
the results indicate that increasing the concentration of the calcium 
sulphate depresses the solubility of the. potash. 
Table IV. —Effect of solutions of calcium sulphate on the solubility of the potash in 
orthoclase 
Solution No. 
Calcium sul¬ 
phate in 100 
c. c. of solution. 
Potassium 
oxid in 
solution. 
I. 
O. OO 
. 018 
■035 
. 070 
. 105 
. 140 
• 175 
a . 210 
6. 0 * 
4 - 5 
3-6 
3-6 
1. 2 
.8 
i -3 
•5 
2... 
3 . 
O * 
4 . . . , . ..... .. 
C. 
6. 
7.... 
8.. .-. 
° Solid phase present. 
