526 KIRK BRYAN 



these systems of classification are complete enough to include all 

 springs, nor are the classes established even mutually exclusive. 

 The names record only the peculiarities of springs, though these 

 peculiarities may and many of them do arise from diverse causes. 



Mineral springs are those which yield water containing in 

 solution (i) unusual amounts of mineral matter, or (2) some 

 uncommon or especially noticeable mineral matter. In distinction 

 other springs are called "common springs." Ground water takes 

 up soluble substances from the rocks through which it flows. In 

 consequence small quantities of soluble matter near the point of 

 emergence of spring water are very effective in changing its com- 

 position. Thus mineral content is at best an uncertain guide to 

 the origin of the water or the cause of the spring. Usage also is not 

 consistent. Many ''mineral springs" yield water of a type that 

 is common in adjacent regions, but because it is unusual in the 

 immediate neighborhood they are distinguished from "common 

 springs." If the water has or is supposed to have therapeutic 

 value, "mineral springs" are often called "medicinal." Mineral 

 springs are classed according to the chemical composition of the 

 water, and one of the most elaborate classifications is that of Peale.' 



Some of the simpler and more generally used terms are self- 

 explanatory. Saline springs contain common salt ; sulphur springs 

 contain compounds of sulphur, usually hydrogen sulphide; chalyb- 

 eate springs contain iron; calcareous or lime springs contain cal- 

 cium carbonate; gypsum or "gyp" springs, gypsum; borax springs, 

 borax, etc. Oil springs contain petroleum suspended in drops in 

 the water. The drops of oil usually rise and form a thin iridescent 

 film on the surface of the water. Inflammable gas may accompany 

 the oil or may occur alone in spring water. Such spring waters 

 have risen through or near beds containing petroleum or natural 

 gas. False oil springs also occur. The iridescent film in these 

 springs is due to iron hydroxide, which at one stage in its formation 

 produces the film. In some springs an oily scum is produced by 

 the decomposition of plants or animals buried but a, few inches or 

 feet below the spring opening. 



'A. C. Peale, "The Natural Mineral Waters of the United States," U.S. Geol. 

 Survey, Fourteenth Annual Report (1894), Part II, p. 66. 



