RELATIONSHIP BETWEEN CHEMICAL COMPOSITION AND THE THERMAL EXPANSION OF GLASSES 1

ABSTRACT Thermal expansion data on soda‐silica, soda‐lime‐silica, soda‐magnesia‐silica, soda‐lime‐magnesia‐silica, soda‐alumina‐silica, soda‐lime‐alumina‐silica, and other glasses, over the range of 25° to 90°C are presented and compared. The relations existing between thermal expansion and chemical composition of the glasses, with the exception of boric oxide glasses, is approximately linear. New so‐called expansion factors calculated by the authors give calculated values for expansion coefficients closer to those observed than do Winkelman and Schott factors.