Results on the temperature dependence of orientational order at constant molar volume in the nematic liquid crystal $p$-azoxyanisole are reported for the first time. These results clearly indicate the failure of theories of the nematic phase which do not include both energetic and steric intermolecular interactions.

• Received 2 May 1972

DOI:https://doi.org/10.1103/PhysRevLett.29.85