Samarium sesquioxide, Sm₂O₃

Samarium sesquioxide, or samaria, Sm₂O₃, may be prepared by the ignition of the hydroxide, carbonate, nitrate, oxalate, etc. It is an almost white powder with a faint yellow tinge, and its density is 8.347. It dissolves readily in acids. The corresponding hydroxide is a gelatinous precipitate that absorbs carbon dioxide from the air. The addition of ammoniacal hydrogen peroxide to a solution of a samarium salt causes the precipitation of a hydrated peroxide, Sm₄O₉.xH₂O or probably Sm₂O₅.xH₂O.