Determination of the Relative Permittivity and Density within the Gas Phase and Liquid Volume Fraction Formed within the Two-Phase Region for (0.4026 CH4 + 0.5974 C3H8) with a Radio Frequency Re-entrant Cavity Kandil, M.E.; Marsh, K.N.; Goodwin, A.R.H.; Journal of Chemical & Engineering Data 2007, 52, 1660-1671