464 EDSON S. BASTIN 
so much a matter of relative solubility of corresponding salts, however, 
as of the particular mineral combinations in which soda and potash 
are most commonly present in rocks. The commonest potash 
minerals are muscovite and the potash feldspars, orthoclase and 
microcline. ‘The commonest soda minerals, on the other hand, are 
the plagioclase feldspars, nephelite, sodalite, etc., which are much 
more readily decomposed. 
The more rapid removal of soda than of potash in the processes 
of rock weathering is apparent from the comparisons which have been 
made by Merrill and others" of weathered rocks with the rocks from 
which they have been derived. 
Another line of evidence is furnished by analyses of stream and 
underground waters of areas whose rocks are of known and uniform 
character. Hanamann? found in studying the stream waters of the 
Erz and Karlsbad mountains in Bohemia that ‘‘the tributaries from 
the granitic highlands are rich in silica, soda, and potash. While in 
the granites of Bohemia . . . . the soda is to the potash as 1:2, we 
find that in the waters this ratio is reversed.”’3 
The granites of Maine as shown by numerous analyses and field 
studies contain potash feldspar, orthoclase or microcline, as their 
dominant feldspar, usually with oligoclase as the subordinate feldspar. 
= a varies in the available analyses from mee Be 
a,O I 
UE 
In the ten analyses of groundwaters from the granitic rocks of the 
The ratio 
; site 2 INO 
states soda dominates over potash in every case, the ratio Ko vary- 
I 17/ @©) ° 6 se . 
—_ . Of especial interest is an analysis of water 
ing from ag to 
t See Geo. P. Merrill, Rocks, Rock Weathering and Soils, pp. 185-213 (1906); also 
Thomas L. Watson, “‘Granites and Gneisses of Georgia,” Bull. gQ-A, Geol. Survey of 
Georgia, pp. 298-348 (1902). 
2 Dr. Jos. Hanamann, ‘‘ Die chemische Beschaffenheit der fliessenden Gewaissers 
Bohmens,” Archiv der naturwissenschaftlichen Landesdurchforschung von Béhmen, 
Band IX, pp. 48, 87, 88. This report discusses also the characters of waters derived 
from other types of rocks. 
3 Translation by the writer. 
4See T. Nelson Dale, “The Granites of Maine,” Bull. 313, U. S. Geol. Survey, 
IgQo7. 
5 F. G. Clapp and W. S. Bayley, ‘“‘Underground Waters of Southern Maine,” 
Water-Supply Paper No. 223, U.S. Geol. Survey, p. 77 (1909). 
