The measurement of the viscosity of gases at high pressures. —The viscosity of nitrogen to 1000 atms

Abstract According to the classical kinetic theory the viscosity of a gas is independent of the density and increases with increasing temperature. The experimental verification of this at ordinary pressures provided “one of the most striking triumphs of the theory.” The viscosity of liquids, however, has been shown to be very sensitive to small changes in density and to decrease with increasing temperature. It is thus of interest to measure the viscosity of gases under increasing pressures in order to follow its change as the density becomes comparable with that of liquids. But little experimental work has as yet been done along these lines. Warburg and Von Babo and P. Phillips have determined the viscosity of carbon dioxide between 20° and 40°C. up to 120 atmospheres. Wildhagen made some measurements with air at room temperature up to 200 atmospheres, and Boyd has worked with nitrogen, hydrogen and their mixtures at 30°, 50° and 70°C., up to 200 atmospheres.