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A hydrostatic balance densitometer with a magnetic suspension coupling has been used to measure the density of liquid toluene in the range from (293 to 373) K and pressures up to 30 MPa. New results of measurements of the density of toluene in the compressed liquid region are presented and compared with literature data. The uncertainty of the present density data is estimated to be within ± 0.01 % across the full temperature and pressure range.

This paper describes the use of a novel method for measuring gas solubilities in polymers. It involves the use of a magnetic suspension device, an instrument with good mass sensitivity and short equilibration times that is able to operate in relatively hostile conditions, At similar temperatures and pressures, isobutane was significantly more soluble in polyethylene than carbon dioxide. The solubilities of both gases increased as the pressure was raised and decreased with increasing temperatures. The effect of temperature on gas solubility was smaller with carbon dioxide than with isobutane. Both isobutane and carbon dioxide were substantially more soluble in polyethylene than nitrogen.

The thermal conductivities of argon, nitrogen and hydrogen have been measured using an apparatus of the transient hot-wire type at three temperatures between 300 and 400 K and at a number of pressures up to 17 MPa for argon and 25 MPa for nitrogen and hydrogen. The results give accurate values for the low-pressure limit of the thermal conductivity and these are compared with theoretical estimates. For argon they are close to the values predicted by rigorous kinetic theory and for hydrogen close to the values predicted by the modified Eucken equation. For nitrogen the new experimental values are below those predicted by the Mason-Monchick equation and well below those predicted by the equation of Viehland, Mason and Sandler, which takes spin polarisation into account. The experimental results also show that the variation of thermal conductivity with density of a particular gas shows very little change with temperature over the range studied.

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