They are found at Byron and Oak Orchard, N. Y.; Blossburg, Pa.; Bath, Richmond and Rockbridge, Va. MAGNESIAN OR EPSOM SPRINGS.--These have a bitter taste. To test any water for magnesia, add to a glass of it a solution of phosphate of soda and some hartshorn; if magnesia is present, the liquid first becomes turbid, and finally minute crystals fall to the bottom. There are Epsom springs at Harrodsburg and Perryville, Ky.; Westport, O.; Raymond, Miss.; Orange County, Ind.; Scott County, W. Va. SALINE OR SALT SPRINGS.--These contain a large percentage of common salt, and are recognized by their taste. They generally contain many ingredients, (generally seven or eight,) but the salt predominates. A well should contain at least ten per cent. of salt to pay for working. The Syracuse spring yields a bushel of salt to every thirty-three gallons; while the Great Salt Lake contains 22 per cent. Among the most important salt wells are those at Syracuse, Salina and Liverpool, N. Y.; Lubec, Me.; Shannondale, Va.; Bath County, Ky.; Athens County, O.; Hartford, Ind.; Saginaw, Mich.; Oneida, Idaho. THERMAL OR WARM SPRINGS.--Any spring is so called, the temperature of which throughout the year is above that of the soil around it. They generally occur near the line of junction between the granite or igneous rocks and the stratified rock (slate or limestone) resting upon its flanks. The temperature of such waters in the United States ranges from 73 to 200 degrees, the latter being reached by the Geysers of Montana. Many iron and sulphur springs are also thermal. The most noted warm springs are at Lebanon, N. Y.; in Bath, Berkley, Monroe and Scott Counties, Va.; Buncombe Counties, N. C.; French Brood River, Tenn.; Meriwether County, Geo.; Washitaw, Ark.; Salt Lake Valley, Utah; near Pyramid Lake, Nev.; along the Malheur and Fall Rivers, Or.; Lincoln Valley, Idaho; on Gardiner’s River, in Madison County, and especially in the Yellowstone Basin, Mont. ARTESIAN WELLS.--To sink a flowing well with any reasonable prospect of success, it is essential that the spot selected should be lower than land in the vicinity, although those higher elevations may be several miles away. The layers of the rocks, also, should dip _towards_ the spot rather than away from it. The best indication, but not a certain one, is a _great_ basin-shaped valley, to the centre of which the rocks dip on one or more sides. Sandy, lime and slate rocks are more propitious than granite.