Page 18 - 1915, Springs of CA.

18 SPRINGS OF CALIFORNIA.
mainly from feldspathic material. Although about equally promi-
nent in rocks, sodium is present in waters in much greater proportion
than potassium. Sodium is usually responsible for the foaming of
steam boilers.
Lithium is considered a valuable medicinal constituent of water
but in most waters is present in too small proportion to warrant
quantitative determination. When present in relatively great
proportion it is often calculated as the carbonate, chloride, sulphate,
or bicarbonate, but 5.3 parts per million of lithium carbonate, 6.1
parts of the chloride, 7.9 of the sulphate, and 9.7 of the bicarbonate,
each contain only one part per million of lithium. Dole * states that
since the medicinal value is due to the lithium, not to its compounds,
a person would need to drink 200 tumblerfuls of water that contains
one part per million of lithium in order to take a medicinal dose of
this substance.
Carbonates are prominent constituents of limestones and dolomites
and are presumably derived primarily from the action of carbon
dioxide as a carrier of calcium, magnesium, and sodium. Carbon
dioxide is always present in the atmosphere and is dissolved in con-
siderable quantity by water. Its presence in excess greatly increases
the solubility of most of the weak-acid compounds that are the chief
constituents of common rocks. The carbonates are the dominant
negative radicles in most waters.
Sulphate is thought to be usually produced by the complete oxida-
tion of sulphur. Sulphated aluminic waters may be produced by the
oxidation of pyrite (an almost insoluble iron sulphide) in the presence
of moisture, forming iron sulphate, which is soluble. Reaction with,
the clay of shales then results in an exchange of part of the iron for
aluminum and magnesium. It is believed that calcic sulphated
waters exchange their calcium for magnesium and sodium in a
similar manner when they pass through rocks containing magnesium
and sodium compounds. Free sulphuric acid is present in a few
natural waters, and acts as a vigorous corrosive.
Sulphide radicles, of which several more complex forms than the
simple sulphide exist in water, are probably derived in some waters
from the partial oxidation of sulphur and in others from the reduction
of sulphates, especially by means of organic matter.
Chloride radicle is present in nearly all waters, and, since the
chlorides of the bases or alkalies found in water are very soluble, is a
prominent constituent of nearly all very highly concentrated waters.
The chloride radicle in waters is probably derived from the direct
solution of sodium and magnesium chlorides.
1 Capps, S. R., Ground waters of north-central Indiana: U. S. Geol. Survey Water-Supply Paper 254,
p. 251,1910.