SPRING, an outflow of water from the earth, or a stream of water at the place of its source. Springs have their origin in the water which falls upon the earth in the form of rain or snow and sinks through porous soils till it arrives at a stratum impervious to water, where it forms subterranean reservoirs at various depths. When the pressure of the water which fills the channels through which it has de scended is sufficient to overcome the resistance of the superincumbent mass of earth, the water breaks through the superficial strata and gushes forth in a spring; or it may find some natural channel or crevice by which to issue. In de scending and rising through various mineral masses the water of springs often becomes impregnated with gaseous, saline, earthy or metallic admixtures, as carbonic acid gas, sul phuretted hydrogen gas, nitrogen, carbonate of lime, silica, carbonate of iron, etc. When these
substances are present in considerable quantity the springs become what are known as min eral springs. Warm and hot springs are com mon, especially in volcanic countries, where they are sometimes distinguished by violent ebullitions. Some springs run for a time and then stop altogether and after a time run again and again stop; these are called in termittent springs. Others do not cease to flow, but only discharge a much smaller quan tity of water for a certain time, and then give out a greater quantity; these are called vari able springs. Spring water is generally es teemed as the most desirable for drinking pur poses and is bottled and sold in many cities. Consult Fuller, 'Domestic Water Supplies for the Farm' (1912) ; Ries and Watson, neering Geology' (1914). See ARTESIAN