Barium Aluminates

Freshly precipitated aluminium hydroxide is dissolved by barium hydroxide solution with the formation of barium aluminates. Metallic aluminium is also attacked by barium hydroxide solution. The following compounds have been described: Al₂O₃.BaO.6H₂O, or 5H₂O, Al₂O₃.2BaO.5H₂O, and Al₂O₃.3BaO.11H₂O. Lower hydrates may be obtained by heating. Halogen compounds are also known, Al₂O₃.BaO.3BaCl₂.6H₂O, Al₂O₃.BaO.BaCl₂.11H₂O, Al₂O₃.BaO.BaBr₂.11H₂O, and Al₂O₃.BaO.BaI₂.11H₂O.