Determination of Viscosities and of the Stokes-Millikan Law Constant by the Oil-Drop Method

Abstract

Viscosities of nine gases, determined by the oil-drop method.—Millikan determined the value of $e$, the elementary charge, from measurements of the rate of fall of charged droplets in air, assuming the coefficient of viscosity to be 1,823 × ${10}^{-7\mathrm{}}$. Now that $e$ is known, the method may also be used to determine coefficients of viscosity. Using carefully purified gases, tested spectroscopically and by density measurements, the results of long series of measurements in argon, helium, hydrogen, methane, ethane, isobutane, nitrous oxide, and carbon dioxide, when reduced to 23°, come out, respectively, 2,210, 1,981, 880, 1,079, 927, 755, 1,449, and 1,471, each times ${10}^{-7\mathrm{}}$. These agree with such other reliable determinations as are available for comparison, and are probably accurate to within 0.3 per cent. Isobutane is the first gas whose viscosity has been measured near its condensation point.