This section is from the book "Materia Medica And Therapeutics Inorganic Substances", by Charles D. F. Phillips. Also available from Amazon: Materia medica and therapeutics.
Braun, in his excellent treatise (edited by Dr. H. Weber, 1875), classifies "Mineral Waters" somewhat as follows:Class 1 - Carbonic Acid Waters comprise many of various character, more or less impregnated with this gas, which renders them easier of digestion, and chemically assists the solution of bicarbonates, e.g., of soda and iron. Their medicinal properties are, to lessen gastric irritability, to stimulate slightly the secretions of the stomach and of the kidneys, and to increase the peristaltic action of the intestines.
There are a few springs which contain only a small amount of saline ingredient with so much gas that they may be called simple acidulated or carbonated waters, but none of these are active enough to be in demand beyond their own locality. All the commonly used aerated waters contain a notable proportion of alkalies, chlorides, earths, or iron, and hence, although containing carbonic acid, find their place rather in the following classes.