Viscosity of methane to 6 GPa and 673 K.

A rolling-sphere technique has been used to measure shear viscosities of (supercritical) fluid methane in a diamond-anvil cell between temperatures of 294 and 673 K, up to a pressure of 6 GPa. A correlation between a reduced viscosity and reduced residual entropy is shown to give a good account of much of the extant data, both from this study and the literature.