Abstract
The vapor pressure of benzene and the heat of dilution of benzene‐biphenyl mixtures have been measured at 25°C. The results are shown to be in fair agreement with Guggenheim's formulae based on the lattice model, assuming that the biphenyl molecule occupies twice the volume of the benzene molecule, and that the coordation number of the lattice is between 6 and 12. No agreement can be obtained if the effect of the different sizes is neglected. The experimental results of other authors are critically examined and shown to conform to the above picture.