Resistance anomaly in a weak acid near the critical point

Recently published data on the resistance anomaly in a critical isobutyric acid-water mixture near the phase-separation critical point are analyzed. It is shown that the data below a value of t≡(T-Tc)Tc5×10^-5 may be influenced by gravitational effects which were not accounted for in the original analysis. In the temperature range above this value of t, a fit of the form (Rc-R)Rc≈At^1-α+Bt (with α the specific-heat exponent) is shown to be satisfactory, and a semiquantitative theory which yields this result is presented.