It was previously shown that one constant per element (other than oxygen) sufficed to calculate the refractive indices (for a single wave-length) of a wide variety of silicate glasses from their compositions and densities. It is now shown that with an additional constant per element (other than oxygen) the dispersions in the visible range can be computed. The average deviation between experimental and calculated values for nF—nc is about 5 to 8 ×10-5, in those systems for which the most accurate data are available.
MAURICE L. HUGGINS, "The Dispersion of Silicate Glasses as a Function of Composition," J. Opt. Soc. Am. 30, 514-518 (1940)