Green vitriol Meaning, Definition & Usage

Definitions
  1. ferrous sulphate; copperas. See under Green.
Definitions
  1. . (a) (Chem.) Sulphate of iron; a light green crystalline substance, very extensively used in the preparation of inks, dyes, mordants, etc. (b) (Min.) Same as copperas, melanterite and sulphate of iron.

Webster 1913