A Study of the Evaporation of Small Drops and of the Relationship Between Surface Tension and Curvature

Abstract

The rates of evaporation of n‐dibutyl phthalate droplets ranging from 3μ to 0.5μ in radius were measured in a Hoag type of Millikan's oil‐drop apparatus under different conditions of vapor pressures. The data obtained are interpreted in two ways. One interpretation is based on an equation derived from Fourier's equation of diffusion; the results thus obtained show that the surface tensions of the droplets decrease with increasing curvature. The other is based on an equation derived on the basis of an assumption of a vapor film surrounding the evaporating droplet; the results obtained here lead to the validation of Lord Kelvin's equation. An explanation is also given for the abnormally high values of surface tension obtained by Woodland and Mack.