THERMOGRAVITATIONAL MEASUREMENT OF THE SORET COEFFICIENT OF LIQUID-MIXTURES

We have designed and constructed a thermogravitational column for dete rmining the Sorer coefficient of liquid mixtures. The excellent agreem ent of the results obtained for toluene and n-hexane mixtures with rec ent accurate measurements performed by optical methods shows the valid ity of the thermogravitational method when a column with the correct g eometry is used. We have applied this technique to determine the Soret coefficient of the binary systems benzene-n-heptane and carbon tetrac hloride with cyclohexane, methanol and ethanol. Comparison with the li terature data allows us to determine the reliability of the existing m easurements of thermal diffusion for these mixtures.