AbstractEquations are given for the calculation of changes of density, refractive index, and other optical constants produced by the addition of a known relative weight of a given component to a base glass. Corresponding equations for the substitution of one component for another are also given. Values are computed and listed for the initial fractional rate of change of refractive index (nD) when various components are added to (a) pure SiO2and (b) a sodium silicate glass containing 50% of Na2O by weight.