On the viscosities of the gases of the argon group

Abstract

In a previous paper (p. 265, supra ) I have described a method which is especially suitable for comparing the viscosities of small quantities of different gases. I have now made use of it for determining the viscosities of specimens of helium, neon, argon, krypton, and xenon, which were very kindly placed at my disposal by Sir William Ramsay. The results here recorded are for atmospheric temperatures only, but the measurement of the temperature variations will at once be proceeded with. For this purpose, however, the apparatus will have to be somewhat modified; and in view of the important bearing of viscosity upon the kinetic theory of gases and molecular properties, it has been thought unwise to delay publication. Theory of the Method . A diagram of the principal part of the apparatus is given in fig. 1. It consists of two tubes connected together at both ends, and two taps for admitting and extracting the gas enclosed. The tube M is a fine capillary tube about 50 cm. long, and the tube N is much wider in internal cross-section, but is nevertheless sufficiently narrow for the pellet of mercury P to remain intact in it. When the tubes are held vertically, the mercury pellet travels slowly downwards, driving before it the gas enclosed through the capillary tube. The apparatus may be filled with various gases whose viscosities—subject to a small correction to be mentioned later—are simply proportional to the times occupied by the mercury pellet in describing the distance between the marks y and z . That is to say, if t 1 and t 2 are the times of fall for two different gases, ŋ 1 / ŋ 2 = t 1 / t 2 . (1)