With weld and cochineal, which are colouring matters the most sensible to the action of sulphate of iron, the purified alums gave us colours more brilliant, fresh, and in a slight degree lighter; while those with our common alums were all duller, and evidently of a deeper hue.
1807, William Nicholson, editor, A Journal of Natural Philosophy, Chemistry, and the Arts, volume XVIII, page 286