“…Liquid-phase activity coefficients, obtained from vaporliquid equilibrium data, can give In by direct application of Equation 8-for example, the methane-oxygen vaporliquid data of Hodges and Burch (1967) yield In = 0.03, in agreement with our results obtained from solid-liquid data. If no liquid-phase information is available, we can turn to gas-phase data.…”