The Physical Properties of Glasses. Part VII. The Molecular Refraction of Glasses

JSGT 1946 V30 T310-T317

It is shown that the molecular refraction of abnormal glasses can be calculated in an additive way, with the aid of atomic (ionic) refractions, provided that distinction is made between bridging and nonbridging oxygen ions. This additivity is not expected for the normal glasses. These· expectations are found to be realised for a large number of pure silicate glasses containing Na⁺, K⁺ and Ca⁺⁺ ions only. The deviations between experimental and calculated molecular refractions for the abnormal glasses are less than 0·3%. Glasses containing isolated oxygen tetrahedra are not examined.

J. M. Stevels