\Po*tas"si*um\, n. [NL. See {Potassa}, {Potash}.]
(Chem.)
An Alkali element, occurring abundantly but always combined,
as in the chloride, sulphate, carbonate, or silicate, in the
minerals sylvite, kainite, orthoclase, muscovite, etc. Atomic
weight 39.0. Symbol K (Kalium).
Note: It is reduced from the carbonate as a soft white metal,
      lighter than water, which oxidizes with the greatest
      readiness, and, to be preserved, must be kept under
      liquid hydrocarbons, as naphtha or kerosene. Its
      compounds are very important, being used in glass
      making, soap making, in fertilizers, and in many drugs
      and chemicals.
{Potassium permanganate}, the salt {KMnO4}, crystallizing in
   dark red prisms having a greenish surface color, and
   dissolving in water with a beautiful purple red color; --
   used as an oxidizer and disinfectant. The name {chameleon
   mineral} is applied to this salt and also to potassium
   manganate.
{Potassium bitartrate}. See {Cream of tartar}, under {Cream}.