Alkalies

Chemically, a cla of substances, as caustic soda, NaOH, and caustic potash, KOH, which have the power of neutralizing acids, of changing red litmus to blue, and po e a peculiar soapy feeling when in contact with the fingers. Ammonium hydroxide and carbonate and the oxides, hydroxide and carbonates of the alkali and alkaline earth metals po e the first two qualities. Of these, sodium, pota ium, calcium, and magnesium are nece ary for the development and maintenance of the body, calcium being the most important and magnesium the least so. They correct undue acidity of the stomach and of the fluids of the body, as in gout or rheumatism. The oxides and hydroxides are powerful caustics and corrosives, and taken internally in sufficient quantities give rise to fatal results; the carbonates are also more or le caustic, but, except in large amount, not dangerously so.