1911 Encyclopædia Britannica/Vitriol

VITRIOL, a name given to sulphuric acid and to certain sulphates. Oil of vitriol is concentrated sulphuric acid. Blue or Roman vitriol is copper sulphate; green vitriol, ferrous sulphate (copperas); white vitriol, zinc sulphate; and vitriol of Mars is a basic iron sulphate.