Abstract
The Matano‐Boltzmann method of graphical calculation of diffusion coefficients in solutions is replaced by an analytical method in certain systems. This procedure enables accurate calculation of diffusion coefficients near the concentration extremes. An equation is derived for the diffusion coefficient D as a function of concentration c. The equation predicts a variation of D with c which is not exponential in metallic systems, contrary to the proposal of Wagner. Comparison of D values with those obtained graphically, for the system copper‐nickel, indicates that the graphical values may be appreciably in error at that extreme where the diffusion coefficient is greatest.