Fluids of larger polyatomic molecules do not well fit the hard sphere model of dense fluids as their liquid range, reduced in terms of relative molecular volumes, usually extends well beyond the freezing density of the hard sphere fluid. Even where overlap occurs, the density dependence is observed to be not as simple as that of the model. It is for this reason that empirical functions for the density dependence of the transport properties have been developed. Application of such correlations has thrown some doubt on previous high-pressure measurements of the viscosity of liquid octane and toluene. New measurements have been made for octane between 283 K and 348 K and for toluene at 298 K and 323 K at pressures up to approximately 375 MPa with a falling-body viscometer. These are supplemented by pVT measurements for octane between 278 K and 298 K, which have been used to improve an earlier equation of state. The viscosity results are compared with earlier data using a general correlation method for molecular liquids.

The effect of pressure on the volume of liquid 1,2-dichloro-1,2,2-trifluoroethane (R123a) has been measured relative to the volume at 0.1 MPa with a bellows volumometer for pressures up to 380 MPa over the temperature range (278.15 to 298.14) K and up to about 275 MPa for (313.14 to 338.13) K. The experimental volume ratios have been represented by equations to enable interpolation and extrapolation of volumetric properties. Isothermal compressibilities, isobaric expansivities, internal pressures, and the change in isobaric heat capacity from its value at 0.1 MPa have been calculated. Although there are similarities between these properties and those of 2,2-dichloro-1,1,1-trifluoroethane (R123), there are differences, indicating the effects of the greater asymmetry of the molecular structure of R123a.