Distillation

Chromatography: And Analogous Differential Migration Methods

“…Thermal diffusion transverse to gravity is especially effective for the fractionation of isotopic gases (12,36,37,81,86,87,147,148), and it has been utilized for the fractionation of liquids such as tall oil (79). This combination of forces resembles that in the distillation column (87), also adapted to the separation of isotopes (4), but here the separation of the vapors of the components is enhanced by the intervening zones of the condensed refluxing phase (4,12,87,137). An analogous effect is obtained in the thermal diffusion column by the addition of "Hilfsgase," gases that form zones between those to be separated (37,147,148).…”