Glasses – 3,935,018

Abstract Inorganic oxide glasses having compositions within the range (in moles percent) B.sub.2 O.sub.3 1.2-3.5, P.sub.2 O.sub.5 50-72, PbO 0-30, transition metal oxides 0-5, the remainder being oxides selected from alkali metal oxides, alkaline earths and zinc oxide.