The Coefficients of Viscosity and of Slip of Air and of Carbon Dioxide by the Rotating Cylinder Method

Coefficients of viscosity of air and of C${\mathrm{O}}_2$, determined by the constant deflection method.—With the rotating cylinder apparatus designed by Millikan and used by Gilchrist, Harrington, Yen and Stacy in measurements of high precision, a new determination has been made of the coefficient of viscosity of dry air. The value obtained, ${\eta }_{23}=1822.1\mathrm{}\times {10}^{-7\mathrm{}}$, is only 1/40 per cent less than the standard value of Harrington. The coefficient of viscosity of C${\mathrm{O}}_2$ obtained by the same method comes out ${\eta }_{23}=1471.5\mathrm{}\times {10}^{-7\mathrm{}}$. The gas used was from c.p. NaHC${\mathrm{O}}_3$, and since, after purification by freezing, various samples gave concordant results, this value is thought to be correct to within 1/20 per cent. Comparison with the results of Breitenbach indicates that all his values, though relatively correct, are 1.5 per cent too high.