The thermal diffusion factor and temperature

Abstract
The thermal diffusion factor has been measured for several gas mixtures in a range of temperature which included that at which the reversal of sign, predicted theoretically when a Lennard-Jones type of interaction is assumed, might be observed. A reversal was found with hydrogen-deuterium, nitrogen-argon, oxygen-argon and nitrogen-carbon dioxide mixtures; with neon-argon, argon-krypton and krypton-xenon mixtures no reversal was observed, the thermal diffusion factor having a small positive value at the lowest temperatures at which measurements could be made. A comparison of the experimental values of the thermal diffusion factor with values calculated for the Lennard-Jones (13, 7) model shows that this model is not quantitatively satisfactory.