This report presents more extensive experimental vapor‐liquid equilibria data for the helium methane system than are found in the literature. A static sampling technique was used to obtain vapor and liquid compositions for six temperatures between −180° and −85°C. and pressures up to 2,000 lb./sq.in.abs. Data at 2,000 lb./sq.in.abs. were extended to the critical temperature of the mixture. Average scatter of the data from the smoothed lines is approximately 1% of the helium concentration or 0.03 mole % helium, whichever is larger. Vapor compositions at −140°, −160°, and −180°C. were analyzed by a different technique and scattered on the average from the smoothed curve less than 4% of the methane concentration. Comparisons are drawn between the data of this study and the previously published work of Kharakhorin. The solubility of helium in liquid methane was found to be considerably less than the values indicated by Kharakhorin. Experimental data are presented in tabular form and in various phase composition diagrams. The behavior of the helium‐methane system is seen to be very similar to that of the helium‐nitrogen system, with helium being much less soluble in methane than in nitrogen. The data were satisfactorily represented by means of the Krichevsky‐Kazarnovsky equation. Extrapolations to higher pressures should be feasible.

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NOMENCLATURE P, = vapor pressure of pure component i at equilibrium temperax, = mole fraction of component i in the liquid phaae y8 = mole fraction of component i in the vapor phase 7 , = activity coefficient of component i x = total pressure, mm. of Hg Subscripts ture, mm. of Hg 1 = hexamethyldisiloxane 2 = n-propyl alcohol ACKNOWLEDGMENT The services of R. Engineering students, in the experimental phases of this investigation, are gratefully acknowledged.Figure 3. Density at 25" C. vs. weight fraction hexamethyldisiloxane for the system hexamethyldisiloxane-n-propyl alcohol Data were obtained for the solubility of helium at pressures up to 2000 p.s.i.a. in liquid argon at temperatures of -125O, -140°, -160°, and -180°C.; in liquid oxygen at -130°, -145', -160°, -180°, and -195.8"C.; and in liquid carbon monoxide at -145', -160', -180°, and -195.8" C. A static sampling technique was used and samples were analyzed by gas chromatography. The data are presented in temperature-composition and pressure-composition diagrams. A comparison is madebetween the data of this study and previously published data for the helium-argon and helium-oxygen systems.

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