Thermal Diffusion in the Critical Region. II

The previous measurements on thermal diffusion in the critical region for the system ethane-xenon are extended and completed, with the use of a modified radioactive tracer technique. A rough calculation of cluster size in the critical region is made. A mechanism of molecular motion in the dense gas above the critical point, consistent with the data is present. It is shown that the transformation between dense gas and liquid occurs without discontinuity as far as thermal diffusion is concerned. The thermal diffusion columns operated in the region of turbulent heat transfer gave a separation as predicted by the modified theory of the column.