A method of controlling an in-series, multiple, e. In a preferred mode of this purification procedure, the felt is heated in an aqueous solution of an inorganic oxidant, such as nitric acid, a mixture of hydrogen peroxide and sulfuric acid, or a potassium permanganate. Furthermore, a screw thread is in an inverse direction to that of the screw thread of the outside wall, is configured on an inside wall of the fixing cap, moreover, a plurality of grooves are defined on a side edge of an opening of a bottom portion of the fixing cap. The windshield glass anchor includes a windshield glass clamp and a pivot extension that extends from the windshield glass clamp.