The dielectric permittivity of saturated liquid carbon dioxide and propane measured using cross capacitors

Relative dielectric permittivities εr of saturated liquid carbon dioxide (CO2) and propane (C3H8) were measured using well-characterized cross capacitors in the range 260 K \wp_{\rm sat} \equiv (ε_{\rm r} -1)/[(ε_{\rm r} +2) \rho_{\rm sat}] of CO2 was calculated using the equation of state of Span and Wagner to convert our values of the saturation vapor pressure psat to values of the saturated liquid density ρsat. In the range 260 K \wp_{\rm sat} = (7.659\pm 0.001) cm3• mol−1. The systematic difference between measurements made with two different capacitors was 0.001 cm3• mol−1; this difference is equivalent to a shift of 12 mK in the liquid temperature. The uncertainty of \wp_{\rm sat} from the equation of state of CO2 is approximately 0.002 cm3• mol−1. Our values of \wp_{\rm sat} for CO2 are consistent with the results of Moriyoshi et al. and of May et al.; however, our values are 0.5 % larger than the values determined by Haynes. For saturated liquid propane, our values of εr agree with the values of Haynes and Younglove within the combined uncertainty of 0.0003.