Abstract: Porcelain compositions, especially dental porcelain compositions, which contain leucite crystals in controlled amounts in a glassy phase matrix to permit selective adjustment of the thermal coefficient of expansion of the porcelain compositions, including methods of preparing and using same and products derived therefrom.

Abstract: A method for manufacturing the insulating layers of a glass multilayer wiring board from a mixture of (1) 30-90 wt. % of a borosilicate glass consisting of 55-75 wt. % of SiO.sub.2, 13-25 wt. % of B.sub.2 O.sub.3, 5-13 wt. % of Al.sub.2 O.sub.3, each 1-5 wt. % of PbO, MgO, and BaO, and each 1-2 wt. % of Na.sub.2 O and K.sub.2 O and (2) 70-10 wt. % of a silica glass, is provided.

Abstract: There are obtained metal effect glazes having broad displays of colors, which also can be employed for rapid firing conditions by treating 75-95% of a base glaze made of 20-55% PbO, 0.1-10% Na.sub.2 O, 1-15% CaO, 1-18% Al.sub.2 O.sub.3, and 8-81% SiO.sub.2 with 5-25% of a color body made of 10-80% MnO.sub.2, 1-20% Cu, 0.1-50% TiO.sub.2, and 0.01-20% NiO.

Abstract: A glass having a composition which would result by mixing from 20 to 80 weight percent of glass A with 80 to 20 weight percent of glass B and melting the mixture to form a homogeneous glass:______________________________________ Glass A Glass B Weight Weight Percent Percent ______________________________________ SiO.sub.2 1.8-2.2 SiO.sub.2 67-70 B.sub.2 O.sub.3 14-16.5 Li.sub.2 O 14-17 PbO 69-72 Al.sub.2 O.sub.3 4-5.5 ZnO 8.2-9.2 CaO 9-12 BaO 2.7-3.5 ______________________________________said glass having a coefficient of thermal contraction from 15.degree. C. below the annealing point to room temperature of from 106 to 115.times.10.sup.-7 /.degree.C.