Diffusion in polyethylene glycols has little relation to their molecular weight or viscosity. Diffusion in methyl-silicone elastomer SE-30 was anomalous, so that comparison with the light methyl-silicone oil SF-96-200 is unreliable. Diffusion of n-alkanes appeared much faster in the elastomer with an indication that this would be untrue of more strongly retained alkanes, but the oil gave neater more symmetrical peaks. This behavior is unexplained. Energy of diffusion is lower in the methyl-silicones, making them more suitable for programmed temperature chromatography. Equations are given relating diffusivities of n-alkanes in methyl-silicones and of n-alkanols in polyethylene glycols to carbon number and temperature.