Barium oxidizes in air, and it reacts vigorously with water to form the hydroxide, liberating hydrogen. In moist air it may spontaneously ignite. It burns in air to form the peroxide, which produces hydrogen peroxide when treated with water. Barium carbonate is used in glass, as a pottery glaze, and as a rat poison. The chlorate and nitrate are used in pyrotechnics to provide a green color.
Barium chloride is used in medicinal preparations and as a water softener.
Barite, the sulfate ore, has many industrial uses. Because barium sulfate is virtually insoluble in water and acids, it can be used to coat the alimentary tract to increase the contrast for X-ray photography without being absorbed by the body and poisoning the subject. Barium salts give a characteristic green color in the flame test . Barium metal was first isolated in 1808 by Sir Humphry Davy by electrolysis.