Diffusion coefficients of cesium and potassium vapors in helium and argon

Experimental apparatus for determining diffusion coefficients of alkali metal vapors in inert gases by Stephan's method is described; data obtained for mixtures of $\mathrm{Cs}$–$\mathrm{He}$, $\mathrm{Cs}$–$\mathrm{Ar}$, $\mathrm{K}$–$\mathrm{He}$, and $\mathrm{K}$–$\mathrm{Ar}$ are reported.