Nickel Dichromate, NiCr₂O₇.1.5H₂O

Nickel Dichromate, NiCr₂O₇.1.5H₂O, has been prepared4 by boiling a mixture of nickel carbonate and chromic acid in aqueous solution; it crystallises in reddish-brown transparent prisms, which are deliquescent. It readily forms addition compounds with organic bases; for example, pyridine yields NiCr₂O₇.4C₅H₅N. The double salt, NiCr₂O₇.2Hg(CN)₂.7H₂O, has been described. Nickel trichromate has only been obtained in the amorphous condition.