Refractive Index Measurements in Fused NaNO(3) and KNO(3) by a Modified Thermooptic Technique

A thermooptic technique for studying the temperature dependence of refractive index of liquids at room temperature has been modified and applied to the study of molten NaNO(3) and KNO(3) within a temperature range of some 80 K above the melting point for five different wavelengths within the visible spectral range. The experiments show a temperature dependence of the polarizability for the two salts as calculated from the Lorentz-Lorenz formula, which cannot be explained by experimental inaccuracy.