Effect of Light Scattering upon the Refractive Index of Dispersed Colloidal Spheres

Abstract

The Zimm‐Dandliker equation on the effect of light scattering upon the refractive index of colloidaldispersions of spheres is found to be in good agreement with experimental facts. It is transformed to give a new mixture rule from which the refractive index of colloidal spheres, to be expected in absence of light scattering, can be calculated. The latter is needed for particle size determinations in colloidal solutions from light‐scattering measurements to be evaluated on the basis of the Mie theory. For the same purpose, a graphical method is worked out which is less time consuming and yields very accurate results. The graphical method allows one to obtain simultaneously both the refractive index and the diameter of the particles. The method is tested successfully against data obtained by alternate procedures used heretofore.