Barium Percarbonate, BaCO₄

Barium Percarbonate, BaCO₄.aq., is obtained as a light yellow compound by cooling a suspension or solution of barium peroxide to 0° C. and treating with carbon dioxide, the peroxide being always in excess. It is hydrated, and is not to be regarded as BaCO₃.H₂O₂, because neither alcohol nor ether extracts hydrogen peroxide from it, and it only gives up hydrogen peroxide slowly on treatment with water. It is a convenient reagent for the preparation of neutral hydrogen peroxide by treatment either with water or with an acid producing an insoluble barium salt.