mineral water, spring water containing various mineral salts, especially the carbonates, chlorides, phosphates, silicates, sulfides, and sulfates of calcium, iron, lithium, magnesium, potassium, sodium, and other metals. Various gases may also be present, e.g., carbon dioxide, hydrogen sulfide, nitrogen, and inert gases. Ordinary well or spring water, in contrast, contains far fewer substances, mostly dissolved sulfates and carbonates, and calcium and other alkali and alkaline earth metals. Many mineral waters also contain trace elements that are thought to have therapeutic value. Spa therapy, widely practiced in Europe, advocates bathing in and drinking mineral waters as a cure for a variety of diseases. Many authorities believe that the success of such therapy really results from the beneficial effects of rest and relaxation. Famous European resorts include Bath, Spa, Aix-les-Bains, Aachen, Baden-Baden, and Karlovy Vary (Carlsbad). Prominent among resorts in the United States are Poland, Maine; Saratoga Springs, N.Y.; Berkeley Springs and White Sulphur Springs, W.Va.; Hot Springs, Ark.; French Lick, Ind.; Waukesha, Wis.; and Las Vegas Hot Springs, N.Mex. Many mineral waters are now prepared synthetically, the various mineral ingredients being added to ordinary water in proportions determined by careful chemical analysis of the original ingredients. See spring.