Abstract: A glass composition having at least 85 mole percent of SiO.sub.2, where the improvement comprises at least 7 wt percent of at least one member selected from the group consisting of PbO and Bi.sub.2 O.sub.3 and at least 1.5 mole percent of at least one member selected from the group consisting of K.sub.2 O, Rb.sub.2 O and Cs.sub.2 O.

Abstract: The disclosure is directed to a method of making glass via solution deposition of a porous self-supporting body by combination of a first solution and a second solution. The first solution containing at least one basic glass forming solute is confined within a porous container, the walls of which are substantially impermeable to the basic solute. The second solution containing at least one acidic solute is diffused into the porous container through its walls which are substantially permeable to the said acidic solute. Within the porous container the combination between the first solution and the second solution takes place leading to the deposition of a self-supporting porous body on the inside walls of the container. The porous body which is crystalline, vitreous or intermediate between the two, is purified by leaching and/or washing, dried and thermally consolidated to a transparent non-porous glass.

Abstract: A glass article is produced by doping a porous glass matrix with at least one member selected from the group consisting of PbO and Bi.sub.2 O.sub.3 and at least one member selected from the group consisting of K.sub.2 O, Rb.sub.2 O and Cs.sub.2 O, and producing a profile in dopant composition by immersion in a multiple-solvent solution.

Abstract: A glass composition having at least 85 mole percent of SiO.sub.2, where the improvement comprises at least 7 wt percent of at least one member selected from the group consisting of PbO and Bi.sub.2 O.sub.3 and at least 1.5 mole percent of at least one member selected from the group consisting of K.sub.2 O, Rb.sub.2 O and Cs.sub.2 O.