The number of mineral waters is legion. There are many hundreds of them known in the United States, and in foreign countries they are almost, if not quite, as numerous. Only a few waters have acquired world-wide reputation, but many waters that have not acquired this reputation are of equal excellence. The classification of mineral waters has been arranged by Haywood1. In some respects it is the best classification which has been published, especially by reason of its compactness. It is as follows:

1United States Department of Agriculture, Bureau of Chemistry, Bulletin No. 91.

Haywood gives further explanation of some of the groups classified, as, for instance, thermal waters, which are those which issue from the earth at a markedly higher temperature than the surrounding atmosphere. He defines alkaline waters as those which have an alkaline reaction and contain carbonic or bi-carbonic acid ions in predominating quantities. Saline waters are those which have an alkaline or neutral reaction and contain sulphuric, muriatic, or nitric acid ions in predominating quantities. Alkaline-saline waters lie between the alkaline and saline. They embrace those which have an alkaline reaction and contain (1) sulphuric, muriatic, or nitric acid ions along with carbonic or bicarbonic acid ions, both classes being present as predominating constituents or those which have an alkaline reaction and (2) those that contain sulphuric, muriatic, or nitric acid ions along with boric or silicic acid ions. Acid waters are those which have an acid reaction, and contain either sulphuric or muriatic acid ions in predominating quantities.