In these subdivisions the foundation is in all cases the same. The mixed clay or “paste” or “body” (varied in composition according to the nature of the glaze to be superimposed) is formed by the hand, or on the wheel, or impressed into moulds; then slowly dried and baked in a furnace or stove, after which, on cooling, it is in a state to receive the glaze. This is prepared by fusing sand or other siliceous material with potash or soda to form a translucent glass, the composition, in the main, of the glaze upon siliceous wares. The addition of a varying but considerable quantity of the oxide of lead, by which it is rendered more easily fusible but still translucent, constitutes the glaze of plumbeous wares: and the further addition of the oxide of tin produces an enamel of an opaque white of great purity, which is the characteristic glazing of stanniferous or tin-glazed wares. In every case the vitreous substance is reduced to the finest powder by mechanical and other means, being milled with water to the consistency of cream; into this the dry and absorbent baked piece is dipped and withdrawn, leaving a coating of the material of the bath adhering to its surface. A second firing, when quite dry, fuses this coating into a glazed surface on the piece, rendering it lustrous and impermeable to liquids. The two former of these glazes may be variously coloured by the admixture of metallic oxides, as copper for green, iron for yellow, &c.; but they are nevertheless translucent, and show the natural colour of the baked clay beneath. VITREOUS OR GLASS-GLAZED WARES.