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Accurate binary diffusion coefficients measured over the temperature range 275-323 K, together with some excellent virial coefficients in the literature, have been used to derive (m,6,8) potential parameters for the systems He-CH4, He-CF4, He-O2, Ar-O2, CH4-C2H6, CH4-C3H8 and CH4-C4H10. These parameters predict quite well the viscosities reported for these systems by Kestin and coworkers. The results indicate that binary diffusion coefficients can be used to predict viscosities more accurately than binary viscosities can be used to predict diffusion coefficients.

A Loschmidt cell has been used to measure the pressure dependence at two temperatures of the binary diffusion coefficients of four systems containing helium. The results are used (a) to show that the Thorne–Enskog theory for moderately dense gases is not adequate to describe diffusion in these systems and (b) to indicate that a temperature dependence of the Thorne correction could not be detected.