An experimental investigation of thermal diffusion was carried out using a levitated iron sample and, a binary gas mixture of hydrogen and hydrogen sulphide . The iron was liquid and the moving gas stream was at room temperature. A range of drop temperatures, gas flow rates and compositions was studied.
The fluxes due to thermal diffusion were found to be significant in this particular system. Interpretation of the rate data for the sulphurisation and desulphurisation of the iron showed a pronounced effect of thermal diffusion upon rate and equilibrium measurements.
An overall rate expression which accounts for thermal diffusion and normal mass transfer in the gas phase has been developed. It is in agreement with experiment. Equillibrium data in the literature have been corrected for thermal diffusion error by means of this expression. These corrected equilibria are in agreement with measurements made by crucible techniques.