Observation of the anomalous refractive index of a critical binary fluid. [Methanol-cyclohexane]

The first observation of the anomaly in the real part of the refractive index of a critical binary fluid (methanol--cyclohexane) is reported. A theoretical relation was obtained for the refractive index of a binary mixture in the vicinity of its critical point which agrees with the experimental results within the experimental error. More precise experiments are in progress. (auth)