Preliminary report on the diffusion of solids

Although 19 years has elapsed since Roberts-Austen published his classical paper on the diffusion of solid metals, no attempt seems to have been made to verify his important results and conclusions or to extend the investigations to minerals and to the great number of solids in which diffusion may be expected to occur. Progress has been made by means of chemical and electrical methods in the detection of diffusion in a number of metals in the solid state, some progress has been made in explaining the phenomena of diffusion on the basis of osmotic pressure and the kinetic theory, and recent measurements of the vapor pressures of solids have contributed indirectly to the progress of the science, but investigators have not undertaken the difficult and essential task of making definitive determinations of the coefficients of diffusivity at various pressures and temperatures.