Jan. 2, 1917 
Availability of Potash in Orthoclase-Bearing Soils 
23 
were shaken for 13 days and the clear solutions then analyzed for potash 
by the colorimetric method described by Cameron and Failyer. 1 The 
amounts of potash in these solutions is shown in Table I. 
Table I .—Effect of solutions of calcium hydroxid on the solubility of the potassium in 
pegmatite 
Solution No. 
Calcium oxid 
in 100 c. c. 
of solution. 
Potassium 
oxid in 
solution. 
Gm. 
P. p. m. 
I. 
O. OO 
3 - 1 
2 . . . 
.0123 
3- 1 
3 . 
. 0246 
2- 5 
4 . 
. 0369 
3 * 1 
5 . 
. 0492 
3 - 0 
6. 
.0738 
3 *o 
7 . 
. 0984 
3 - 1 
8. 
a, 1230 
2.8 
<* Solid phase present. 
The amount of potash recovered is so nearly uniform that these results 
could very well be considered to be multiplicate determinations of the 
potash content of the same solution. There is no evidence that the lime 
liberated any potash from pegmatite. 
Other 10-gm. portions of pegmatite were weighed out and placed in 
shaker bottles. To each portion was added 1 liter of distilled water, 
with varying amounts of calcium sulphate, as shown in Table II. These 
mixtures were shaken for six days and the solutions then analyzed for 
potash. The amounts of potash found in solution are given in Table II. 
Table II .—Effect of solutions of calcium sulphate on the solubility of potash in pegmatite 
Solution No. 
Calcium 
sulphate in 
100 c. c. of 
solution. 
Potassium 
oxid in 
solution. 
X. 
Gm. 
0. 00 
. 0221 
. 0446 
.0668 
. 0864 
* 1330 
. l66o 
a . 2100 
P. p. m. 
2.7 
2. 1 
2. 1 
2. 0 
3*2 
2. 2 
2. 1 
2. 8 
2.. 
4.. . , .. 
6. 
7. 
8. 
a Solid phase present. 
As in the case of the calcium-hydrate solutions, there is no indication 
that the presence of calcium sulphate led to any replacement of the 
potash in pegmatite by lime. 
1 Cameron, F. K., and Failyer, G. H. The determination of small amounts of potassium in aqueous 
solutions. In Jour. Amer. Chem. Soc., v. 25, no. 10, p. 1063-1073. 1903. 
