Experimental Evidence Concerning the Law of Rectilinear Diameter

The critical density ρc of Xe has been determined by two independent methods. The first value, 1.1128 ±{} 0.0003 g/cm³, is based on coexistence-curve data and extrapolation to the critical temperature using the "law of rectilinear diameter." The second method, based on critical-isotherm data and an analysis of gravitational effects, reveals no deviation of the diameter from linearity within the limits of error. If ρc differs from the extrapolated value, the difference is less than 0.5%.