An equation was derived which related the chemical diffusion coefficient to the tracer diffusion coefficients and the electric conductivity. In order to check the validity of this equation, sectioning and flame spectrophotometric measurements were made of the chemical diffusion coefficient and the contact method was used to determine the tracer diffusion coefficient of 42K (figures 22 and 23). Diffusion in KCl-RbCl2 Mixed Crystals. W.Müller, H.Schmalzried: Zeitschrift für Physikalische Chemie, 1968, 57[3-6], 203-17