Vitriols

the industrial name for the crystal hydrates of sulfate salts (sulfates) of certain heavy metals. Among the vitriols used in industry, agriculture, and medicine are blue vitriol (copper sulfate), CuSO₄•5H₂O; green vitriol (ferrous sulfate), FeSO₄•7H₂O; white vitriol (zinc sulfate), ZnSO₄•7H₂O; cobalt sulfate, CoSO₄•7H₂O; and nickel sulfate, NiSO₄•7H₂O.