Anomaly in the heat capacity of nitrobenzene and dodecane

The heat capacity C$_{p}$ of the liquid-liquid mixture nitrobenzene+dodecane has been precisely measured using our own computer-based data acquisition and control, adiabatic calorimeter. A step process of adding heat and then waiting several minutes for a stable temperature assures equilibrium values for the heat capacity from the known heat added and the resulting change in temperature. For a sample at the critical concentration, we observe behavior in the heat capacity consistent with the Ising Model and determine the amplitudes in the one- and two-phase regions to test universal predictions. We acknowledge support from NSF-REU grant DMR 0243811.