It is this latter method of decorating pottery which we will now consider in some of its various forms. CHAPTER II. COLORS FOR PAINTING UNDER THE GLAZE. Colors for painting under the glaze are specially prepared for the purpose from various metallic oxyds. As mentioned in the previous chapter, the colors used under the glaze have less flux or fusible matter in their composition than those used for painting overglaze: this is necessary, because in the former the colors are expected to bear a much greater degree of heat in firing than in the latter. They are so prepared as not to fuse except at the temperature required in the manufacture of the pottery to which they are applied. The variety of underglaze colors is less than that to be found in overglaze colors, as the oxyds from which colors may be made which will stand so great a degree of heat, are few in number. The oxyds from which the colors are prepared are called the bases of these colors. The colors used in underglaze painting are made from the following bases: Blue from the oxyd of cobalt. Co. O. Green from the sesquioxyd of chromium. Cr^2. O^3. Browns from the sesquioxyd commonly called the peroxyd of iron, Fe^2. O^3., and from the sesquioxyd of manganese. Mn^2. O^3. Yellow from the compound of titanium with oxygen, called titanic acid. Ti. O^2. Black from the oxyd of uranium. Red from the suboxyd, or red oxyd of copper. Cu^2. O. We may add, upon the authority of M. Debette, that “pure black is obtained by taking 1 part of oxyd of uranium diluted in 22 parts of glaze; ordinary black with oxyd of manganese or oxyd of iridium; bluish black with a mixture of oxyd of cobalt and of manganese, and smoky grey with chloride of platinum. Rose is obtained by diluting, in glaze, gold which has been dissolved in aqua regia. For the blues, oxyd of zinc and alumina may be mixed with the oxyd of cobalt. For greens may be mixed oxyd of cobalt and oxyd of chromium.” The fluxes used for these bases are given in the following paragraphs, translated from the _Encyclopédie-Roret_: “The matters which enter into the composition of the fluxes and which cause the adherence of the metallic oxyds are quartz, feldspar, borax and boracic acid, nitre, the carbonates of potash and of soda, red lead and litharge, and oxyd of bismuth. At Sevres, they employ, for under-glaze painting, seven kinds of fluxes, which suffice for all the colors. The majority of these fluxes are composed of quartz, oxyd of red lead and of boracic acid, and to some is added a small quantity of carbonate of soda. “The seven fluxes of Sevres are, first, the flint flux, which is prepared by melting quickly in a crucible and then flowing upon a metallic plate a mixture of 3 parts of red lead or of litharge, and 1 part of Etampes sand. “Second. The flux of greys prepared with 6 parts of red lead or litharge, 2 parts of Etampes sand, and 1 part of pulverized borax.