Physical constants of the system methane-hydrogen

Isotherms of methane have been determined for a series of temperatures between 0º and 200º C. by Keyes, Smith, and Joubert, and by Keyes and Burks, but, inasmuch as the highest pressure reached at 0º in these researches was 130 atmospheres, and the isotherm as extrapolated from their derived equation did not indicate the expected pvA minimum at about 150 atmospheres (vide 3), it was deemed advisable to extend the measurements at 0º to 220 atmospheres, and also to determine the isotherm at 20º C. Olszewski was the first to measure the vapour pressures of methane, down to a temperature of –203º C., but his results are chiefly of historical interest. Determinations of the vapour pressures of the liquid between –182º and –150º C. have been made by Stock, Henning, and Kuss, but, apart from a solitary measurement of the triple-point by Crommelin, no modern work seems to have been done on the vapour pressures of the solid. The range between –178º and the critical temperature has been covered by Keyes, Taylor, and Smith in a comprehensive paper upon the thermodynamic properties of methane.