CHAPTER XI. 
The Sulfate Group. 
The sulfates are extremely common in mineral waters. Un- 
der the familiar name of ‘‘salts’’ or ‘‘ Epsom salts’’ we have 
magnesium sulfate, and under the name of ‘‘Glauber’s salts’’ 
we have sodium sulfate. Calcium sulfate, which is soluble in 
water to the extent of 1 part in 380 parts of cold water, is also 
often found, as is a small quantity of potassium sulfate, a sub- 
stance much like sodium sulfate in its properties. 
These are often called ‘‘purgative waters,’’ on account of 
their marked action on the bowels, and as they are, if con- 
centrated, of a bitter-sweet taste, they are also called ‘‘ bitter 
waters.’’ The name Epsom is derived from the name of the 
purging well at Epsom or Ebbesham, near London, once a very 
popular water. 
In regard to water of this class, Doctor Schweitzer says :” 
‘¢ Dolomitic limestones and limestones containing gypsum pro- 
duce the Epsom and Glauber’s salt springs; magnesium sul- 
fate and calcium carbonate resulting from their interaction, 
the former of which is very soluble and constitutes the main 
ingredient of the Epsom salt springs or wells. Such waters 
are nearly all obtained from wells or shafts, sometimes only 
ten or twenty feet deep. They contain, in addition, variable 
amounts of other sulfates but rarely chlorids or carbonates. If 
the limestone above mentioned were associated with marls rich 
in alkalies, or with other rocks containing alkaline carbonates 
or silicates, the conditions are given for the formation of Glau- 
ber’s salt springs. These may be alkaline or neutral, as so- 
dium carbonate or magnesium sulfate happens to be in excess. 
50. Missouri Geological Survey, vol. III, p. 5. 
(164) 
