Barium, a soft, silvery-white, metallic element of the alkaline-earth group, related to calcium. Pure barium is never found in nature. The principal barium-containing minerals are barium sulfate, or barite, and barium carbonate, or witherite. Although barium itself has few industrial uses, its compounds have many applications.

Barium Carbonate

is used in making ceramics and optical glass, and as a rodent poison.

Barium Chloride

is used in lubricating-oil additives, and as a water softener in boilers.

Barium Hydroxide

turns fats into soap, and is used to neutralize acids in the refining of beet sugar; it is also used in insecticides and fungicides.

Barium Nitrate

produces a green hue in flares and other pyrotechnics.

Barium Oxide

is used as a drying agent, and in detergents for engine lubricating oils.

Barium Sulfate

is used as a filler in paper, leather, and rubber. In X-ray photography, a mixture of barium sulfate and water is given to a patient whose digestive tract is to be X-rayed.


a mixture of barium sulfate and zinc sulfide, is a white pigment. It was once widely used in paint, but has been largely replaced by titanium dioxide.

Barium can be hammered into sheets and drawn out into fine strands. It is stable in dry air, but combines with oxygen to form barium hydroxide in damp air or water. Barium was first isolated in 1808 by Sir Humphry Davy, an English chemist.

Symbol: Ba. Atomic number: 56. Atomic weight: 137 33. Melting point: approximately 1,350 F. (732 C.). Boiling point: approximately 3,000 F. (1,649 C.). Specific gravity: 3.5. Barium belongs to Group IIA of the Periodic Table and has a valence of +2.