Thermal diffusion and the approach to the steady state in gases: II

The theory of the rate of approach to the steady state in themal diffusion is tested experimentally on the systems He-Ar, He-CO2, H2-CO2, and D2-CO2 over a temperature range of about -78°c to 325°c. The course of the diffusion has been followed by means of the radioactive tracers 37Ar and 14CO2. The theory appears to be verified, and the results are used to calculate ordinary diffusion coefficients, which are in reasonable accord with previous measurements by other techniques. The thermal diffusion factors, which are obtained from the same measurements, also appear to have reasonable accuracy. The experimental method therefore appears to have promise as a sensitive method for the determination of forces between unlike molecules.