A melting point and cooling curve study of the solid–liquid equilibria in the system anthracene–phenanthrene indicated the existence of a complete series of solid solutions. Investigation of the system anthracene–phenanthrene–Cellosolve at 40 °C revealed that the series is incomplete at this temperature. X-ray studies showed an upper consolute temperature at about 80 °C. The sublimation pressures and vapor pressures of the pure components were measured at temperatures not heretofore studied. Sublimation pressure data for solid solutions at 95 °C gave activity coefficients and indicated positive deviations from Raoult's law. Liquid–vapor isobars were obtained at pressures of 25, 50, and 100 mm, and vapor pressures of dilute liquid solutions of anthracene in phenanthrene found at temperatures near 100 °C. The data point to the existence of an azeotrope of short range. The univariant three-phase line was determined in respect to the pressure, temperature, and composition of the coexisting phases.All the above results were synthesized to give a fairly complete picture of the pressure–temperature–composition phase model, excluding critical phenomena.
