Experimental results of the formation of methane hydrate in dependence of temperature and pressure in unsaturated solutions of NaCl in water will be presented in a temperature range from 261.85 to 285.98 K and pressure up to 11.0 MPa. Furthermore the four‐phase equilibrium NaCl·2H2Os CH4·nH2OsLG has been calculated from the experimental results. Also the heats of transformation of several other equilibria in the ternary system CH4H2ONaCl are obtained.

Gas hydrates of nitrogen and oxygen are described. P -t relations of the three-phase equilibria in the system nitrogen -water are given from -4 to 18°C at pressures up to 1000 atm.The dissociation pressure of oxygen hydrate is given at 0°C.In the late 19th century many solid gas hydrates were described, especially by Villard and De Forcrand 1. Usually these hydrates have low solubility in water. A great increase in pressure is required for these hydrates to persist at increasing temperature.Furthermore, the following relation generally holds : "The lower the boiling point of the hydrate-forming gas, the higher the equilibrium pressure".The most unstable hydrate known so far was reported by Villard in 1896 ; it was argon hydrate, having an equilibrium pressure at 0°C of about 100 atm.Hydrates of the gases He, Hz, Ne, N2, CO, 0 2 , and NO have not been described, although Villard indeed searched for these compounds 1.The availability of a high-pressure apparatus for pressures up to 1000 atm, recently developed in our laboratory 2, has induced a reinvestigation.We have been aided in this by the theoretical calculations of Platteeuw and van der Waals, who expected the equilibrium pressure of N2 and 0 2 hydrate at 0°C to be 90 and 63 atm. respectively 3.Our experiments have actually led to the discovery of the hydrates of NZ and 0 2 , a result which makes us hope that the hydrates of CO and NO will also be found to exist.The apparatus, described in detail in 2, consists of an autoclave of

In an optical high-pressure autoclave with sapphire windows and magnetic stirring, cloud point curves and critical curves in fluid systems of linear polyethylene + ethylene were measured in the temperature range 380-445 K and at pressures from 900 to 2000 bar for a number of polyethylene samples with known average molecular weights and known molecular weight distributions. It is found that an increase in molecular weight of the polyethylene causes a shift of the cloud point curve to higher pressures. The form of the cloud point curves and the position of the critical point are discussed in terms of model calculations by Sole.

p-t relations of different three phase equilibria in the systems nitrogen-water and oxygen-water are given from -6 to 18" for pressures up to 10o0 atm. From the data, the heats of formation of nitrogen-and oxygen-hydrate and the composition of these hydrates were calculated.

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