CARBONATED OR GAS SPRINGS.--Springs of this class have a peculiar sparkling character and are continually sending up bubbles of gas. When the quantity of gas is small, it may be detected by adding a little lime water which will give it a milky appearance and deposit a white sediment; or, dip in a piece of blue litmus paper (which can be had of most druggists), and if there is any carbonic acid gas in the water, it will be reddened; or, pour in a little vinegar, stir well, and then add a little finely powdered sugar, when the gas, if it is there, will rise in small bubbles. The most celebrated carbonated springs are the following: Saratoga and Ballston, N. Y.; Clarendon, Vt.; Sweet Springs in Shover’s Valley, Pa.; Bladon and Bailey Springs, Ala.; “Boiling Springs” near Pike’s Peak, Col.; Beer Springs near Bear River, Or. These springs contain salt, soda, magnesia, lime and iron, and are sometimes classed as _saline_, _soda_ or _chalybeate_ springs. CHALYBEATE OR IRON SPRINGS.--The presence of iron in a spring may be ascertained by pouring into it an infusion of nut-galls, of logwood or of tan-bark, which will change it immediately to a black or dark color. If the water contains much iron, it may be recognized by its inky taste and by a yellowish powder on the border of the spring or at the bottom of a tumbler when allowed to stand awhile. If waters have a cool but earthy taste, they contain lime; if bitter, they have magnesia. The “soda springs,” so called, are often only saline, carbonated or magnesia waters. The most famous iron springs are at Saratoga, Sandlake and Catskill, N. Y.; West Bethel, Fryeburg, Eberne and Bethel, Me.; Schooley’s Mountain in Washington, N. J.; Bedford, Pittsburg, Frankfort and York, Pa.; Brandywine Springs, Del.; Red Sweet Springs in Monroe County, Rawley’s Spring in Rockingham County, and Huguenot Springs in Powhattan County, Va.; in Bath County, Ky.; Yellow Springs, O.; twenty miles east of Knoxville, Tenn.; Madison County, Geo.; Raymond and Lynchburg, Miss.; near Ogden City, Utah; near Mt. Shasta, Col. SULPHUR SPRINGS.--These are easily recognized by their unpleasant odor, resembling that of rotten eggs. The water blackens silver and a solution of sugar of lead. Sulphur springs are very numerous. The best known are at Saratoga, Sharon, Clifton, Avon, Manlius, Chittenango, Dryden and Richfield, N. Y.; Highgate and Newburg, Vt.; Togus, Bethel and West Newfield, Me.; Shover’s Valley, Carlisle and Doubling Gap, Pa.; Winchester and Warrenton, Va.; Greenbrier and Monroe Counties, W. Va.; Bath County, Ky.; White’s Creek near Nashville and in Granger County, Tenn.; Spartanburg, S. C.; Butts County, Geo.; Tallahatta, Ala.; Tampa, Fla.; near Bitter Creek and Great Salt Lake, Utah; along the Yellowstone River, Mont.; Jackson, Cal. ACID OR ALUM SPRINGS.--These waters have a more or less sour taste and redden blue litmus-paper.