Abstract: A highly refractive optical glass (n.sub.d .gtoreq.1.83) with high dispersion (v.sub.d .ltoreq.25) and very good chemical stability at relatively low density (.delta..ltoreq.3.5 g/cm.sup.3) consists of (in weight percent) SiO.sub.2 19-25, Na.sub.2 O 7-10, K.sub.2 O 4-7, Cs.sub.2 O 0-12, Cao 0.5-2.0, BaO 9-15, TiO.sub.2 25-30, ZrO.sub.2 0-6, Nb.sub.2 O.sub.5 16-20, WO.sub.3 0-3, with Nb.sub.2 O.sub.5 :TiO.sub.2 =0.6-0.71.

Abstract: High PbO-content glass in the optical range of flint and heavy flint glasses from the system SiO.sub.2 --PbO--M.sub.2 O wherein M.sub.2 O=alkali metal oxides, said glass having a minimum PbO content of 30 wt. % and a minimum M.sub.2 O content of 0.5 wt. %, are provided with enhanced chemical stability without loss of the desired optical position by replacing a portion of the SiO.sub.2 and PbO such that the glass contains 1.5-6 wt. % (TiO.sub.2 +ZrO.sub.2) and the ratio of TiO.sub.2 :ZrO.sub.2 is about 0.3-2.0.

Abstract: An optical and ophthalmic glass with high refractive index, high Abbe number and low density, which is distinguished by good chemical stability, good crystallization behavior and capability of chemical hardening, comprises (in % by weight):______________________________________ SiO.sub.2 50-63 B.sub.2 O.sub.3 4-8 Al.sub.2 O.sub.3 1-2 Li.sub.2 O 4-8 Na.sub.2 O 4-8 K.sub.2 O 3-7 sum of M.sub.2 O 11-20 (M = Li, Na, K) MgO 0.5-2 CaO 2-5 sum of MO 0-3 (M = Mg, Ca) TiO.sub.2 8-12.5 ZrO.sub.2 1-3 F.sup.- 0-1 As.sub.2 O.sub.3 0.05-0.15 (optional refining agent) Sb.sub.2 O.sub.3 0.0-0.

Abstract: A phototropic glass with the optical characteristics of n.sub.d greater than to or equal to 1.59 and v.sub.d greater than or equal to 44, and with a density less than or equal to 3.0 g/cm.sup.-3 is provided having a composition comprising:______________________________________ SiO.sub.2 42-56 B.sub.2 O.sub.3 11-18 Al.sub.2 O.sub.3 0-5 sum of SiO.sub.2, B.sub.2 O.sub.3, and Al.sub.2 O.sub.3 55-75 Li.sub.2 O 3-9 Na.sub.2 O 0-7.98 K.sub.2 O 0-8.22 sum of alkaki metal oxides 7-15 MgO 3-12 CaO 0-3 SrO 0-3 BaO 0-6 ZnO 0-2 sum of alkali earth metal 3-12 oxides amd ZnO TiO.sub.2 3.06-6.74 ZrO.sub.2 2-11 Nb.sub.2 O.sub.5 2.28-8 La.sub.2 O.sub.3 0-3 Er.sub.2 O.sub.

Abstract: Optical glass with refractive indicies.gtoreq.1.90, Abbe numbers.gtoreq.25 consisting essentially of, in weight percent; 0-10 SiO.sub.2, 2-20 B.sub.2 O.sub.3, 0-2 Al.sub.2 O.sub.3, the sum of SiO.sub.2, B.sub.2 O.sub.3, and Al.sub.2 O.sub.3 being 7.5-25, 1-16 TiO.sub.2, 0-10 ZrO.sub.2, 35-55 La.sub.2 O.sub.3, 0.5-10 Y.sub.2 O.sub.5, 0.5-15 Nb.sub.2 O.sub.5, 0-10 Gd.sub.2 O.sub.3, 0-15 Ta.sub.2 O.sub.5, 0-3 P.sub.2 O.sub.5 wherein the ratio of SiO.sub.2 to B.sub.2 O.sub.3 is between 0.1 and 1.6, and the sum of Nb.sub.2 O.sub.5 and Ta.sub.2 O.sub.5 is from 9 to 20%.

Abstract: An optical and ophthalmic glass with high refractive index, high Abbe number and low density, which is distinguished by good chemical stability, good crystallization behavior and capability for chemical hardening, comprises (in % by weight):SiO.sub.2 --47 to 75B.sub.2 O.sub.3 --1 to 20Al.sub.2 O.sub.3 --0 to 10P.sub.2 O.sub.5 --0 to 5Li.sub.2 O--0 to 15Na.sub.2 O--0 to 10K.sub.2 O--0 to 10CaO--0 to 20MgO--0 to 15SrO--0 to 4BaO--0 to 4ZnO--0 to 5TiO.sub.2 --1 to 15ZrO.sub.2 --0 to 8Nb.sub.2 O.sub.5 --0 to 5 andF----0 to 5.

Abstract: An optical glass with the familiar optical position of n.sub.d >1.70 and v.sub.d >22, which differs from the familiar optical glasses of the optical position due to its lower density and good chemical stability, and is composed of (in percent by weight): SiO.sub.2 25-42, TiO.sub.2 15-35, B.sub.2 O.sub.3 0.5-7, BaO 3-13, CaO 1-3, Nb.sub.2 O.sub.5 1-20, GeO.sub.2 0-2, Al.sub.2 O.sub.3 0-4, Na.sub.2 O 7.5-15, Li.sub.2 O 0-9, K.sub.2 O 2-10, SrO 0-6, ZnO 0-5, ZrO.sub.2 0-3, and WO.sub.3 0-3.

Abstract: A spectacle glass which is colorless in the visible spectrum range, not transmissive in the ultraviolet spectrum range below 350 nm, has a refractive index n.sub.d higher than 1.56 and an Abbe number of more than 45, and which has an extremely low density, has the following composition (in % by weight):______________________________________ 12-40 P.sub.2 O.sub.5 13-34 Al.sub.2 O.sub.3 8-30 SiO.sub.2 0-16 B.sub.2 O.sub.3 4-12 TiO.sub.2 0-4 ZrO.sub.2 2-18 CaO 0-4 MgO 0-15 Na.sub.2 O 0-11 K.sub.2 O 0-6 Li.sub.2 O 0-12 Nb.sub.2 O.sub.5 0-8 ZnO.

Abstract: A new phototropic glass in which the phototropic properties arise from precipitations of silver halide and which in the unirradiated condition is slightly tinted or completely colorless while showing a brown color in the light-exposed condition, comprises, in known phototropic glass compositions, an additional content of at least 0.001 wt % of TeO.sub.2 and/or Yb.sub.2 O.sub.3.