The diffusion of some zinc and cobalt salts in water have been measure
d using an improved version of tile capillary technique. In this techn
ique, diffusion proceeds in the absence of stirring in the bulk soluti
on. ?he amount of diffusing substance which remains in the capillary i
s analyzed after a chosen time. Nanis' solution for three-dimensional
diffusion from a capillary has been used to calculate the experimental
values. The values of diffusion coefficient of zinc iodide, cobalt br
omide and cobalt iodide have been obtained with a diffusion run time o
f four hours. A comparison has been made between the experimental and
theoretical values obtained from Onsager-Fuoss theory, An attempt has
also been made to explain the deviation between the experimental and t
heoretical values over the concentration range studied.