Abstract: A process for producing a porous glass which comprises forming a shaped product of borosilicate glass having a predetermined shape, heat-treating the shaped product for phase separation to form a silica rich insoluble phase and an alkali and boric oxide rich soluble phase, leaching out the soluble phase from the insoluble phase with an acid or an alkali to obtain a porous glass, wherein said shaped product of borosilicate glass is composed essentially of from 45 to 67% by weight of SiO.sub.2, from 0.5 to 10% by weight of Al.sub.2 O.sub.3, from 10 to 30% by weight of B.sub.2 O.sub.3, from 0.5 to 8% by weight of Na.sub.2 O, from 0.1 to 8% by weight of K.sub.2 O+Li.sub.2 O+Cs.sub.2 O, from 0.5 to 7% by weight of CaO, from 0.5 to 15% by weight of MgO+BaO+SrO, from 0 to 10% by weight of ZrO.sub.2 +TiO.sub.2 and from 0.03 to 3% by weight of F+SO.sub.3 +Cl+As.sub.2 O.sub.3 +Sb.sub.2 O.sub.3.

Abstract: A low expansion glass comprising, all by weight, from 55 to 65% of SiO.sub.2, from 10 to 20% of Al.sub.2 O.sub.3, from 2 to 10% of B.sub.2 O.sub.3, from 3 to 10% of MgO, from 1 to 8% of CaO, from 2 to 10% of ZnO, from 0 to 4% of R.sub.2 O where R is an alkali metal atom, and from 0 to 4% of ZrO.sub.2.

Abstract: A ceramic composition for a multilayer printed wiring board, consisting essentially of from 35 to 95% by weight of glass powder and from 5 to 65% by weight of refractory filler powder, said refractory filler powder being at least one member selected from the group consisting of .alpha.-quartz, corundum, zircon and zirconia and said glass powder consisting essentially of from 25 to 40% by weight of SiO.sub.2, from 4 to 15% by weight of Al.sub.2 O.sub.3, from 15 to 25% by weight of B.sub.2 O.sub.3, from 15 to 40% by weight of BaO+CaO+MgO, from 1 to 10% by weight of ZnO and from 0.5 to 5% by weight of ZrO.sub.2.

Abstract: A composition for a multilayer printed wiring board, consisting essentially of from 25 to 65% by weight of glass powder, from 0 to 60% by weight of alumina powder and from 5 to 60% by weight of forsterite powder, said glass powder consisting essentially of from 25 to 70% by weight of SiO.sub.2, from 4 to 15% by weight of Al.sub.2 O.sub.3, from 25 to 45% by weight of B.sub.2 O.sub.3 and from 0.5 to 30% by weight of BaO.

Abstract: A sealing glass composition containing refractory filler of lower coefficient of thermal expansion for use in sealing alumina package for electronic components is disclosed. The composition consists essentially of low melting glass powder and cordierite powder in proportion of 2-30% by weight of the total composition, and optionally, .beta.-eucryptite, .beta.-spodumen, lead titanate or zircon in a proportion, respectively, not exceeding 15% by weight of the total composition. The low melting glass has a composition of 77.0-86.0 wt. % of PbO, 6.0-15.0 wt. % of B.sub.2 O.sub.3, 0.5-6.9 wt. % of ZnO, 0.1-3.0 wt. % of SiO.sub.2, 0-3.0% of Al.sub.2 O.sub.3 0-2.0% of alkali earth metal oxide, 0-1.5% of SnO.sub.2 and 0-1.0% of alkali metal oxide.

Abstract: A sealing composition which can be suitably used for sealing a panel and a funnel of a color television tube is disclosed. The composition consists essentially of 60 - 99 wt.% of low melting devitrifiable glass powder, 1 - 35 wt.% of lead titanate powder and 0 - 5 wt.% of zircon powder. The glass powder has a composition of 77 - 83 wt.% of PbO, 7 - 10 wt.% of B.sub.2 O.sub.3, 7 - 12 wt.% of ZnO and 1 - 3 wt.% of SiO.sub.2.