Abstract
Recently, much interest has been focused upon the preparation of monodispersed colloids using the ``growth by diffusion'' process. Although these colloids are useful tools in experimental procedures, no well‐established reason has been given to explain why the ``growth by diffusion'' method should produce such uniform dispersions. In this paper it is shown that an assembly of competing particles, growing by diffusion, develop the squares of their radii at equal rates. This condition provides a mechanism leading towards uniformity. A method, based on this equal square rule, is suggested for the determination of size distributions in polydispersed systems.