The effect of water vapour on diffusion Coefficients and mobilities of ions in air

Abstract
Determinations of the coefficient of diffusion of positive and negative ions were first made by Townsend. Measurements have since been carried out by Franck and Westphal and Salles using Townsend’s method. The results for air are given in Table I. In spite of the elaborate apparatus used by the later observers their results are little if at all more accurate than those of Townsend.