[Fr., from L. vitrum, glass.] A glassy-looking substance consisting of sulphur and copper or zinc. Also the popular name for sulphuric acid (q. v.). Blue vitriol is sulphate of copper; green vitriol is copperas, or ferrous sulphate; red vitriol is' a native sulphate of cobalt; white vitriol is zinc dissolved in sulphuric acid, and is a sulphate of zinc.