Atomic diffusion in metals was first discovered some sixty-five years ago, and since then a considerable wealth of data has ac cumulated on diffusion in various systems. However, work prior to about the year 1940 is now mainly of historical interest, since ex periments were often carried out under experimental conditions and with methods of analysis leading to uncertainties in inter preting the measured diffusion coefficients. Data on diffusion rates are of importance in processes which are controlled by rates of atomic migration such as growth of phases and homogenization of alloys. In...