Iso-12-tungstoboric Acid, H₉[B(W₂O₇)₆]

Iso-12-tungstoboric Acid, H₉[B(W₂O₇)₆].22H₂O, prepared as above, has no definite melting-point, but decomposes on heating. According to Copaux, a potassium and a barium salt may be obtained by treating the acid with small quantities of the metallic hydroxide, but that these salts are distinct from the ordinary 12-tungstoborates has not yet been conclusively shown.