Writers upon mineral springs generally divide them into the following classes: Carbonated or acidulous, saline, chalybeate or iron, alkaline, sulphur or hepatic, bitter and thermal springs.

The Saratoga waters embrace nearly all of these except the last two; some of the springs being saline, some chalybeate, some sulphur, and nearly all carbonated; and in the list may be found cathartic, alterative, diuretic and tonic waters of varied shade and differing strength. The cathartic waters are the most numerous and the most extensively used. The curative agents prepared in the vast and mysterious laboratories of Nature are very complex in constitution and different in temperature, and on that account do not, like iron, opium, quinia, etc., exhibit single effects; they exercise rather, with rare exceptions, combined effects, and these are again modified by various modes of employment and the time and circumstances of their use.