Influence of surface-active substances on the evaporation of fine water drops

Abstract

1. A method was developed and the possibility of studying the rate of evaporation of small individual drops, which show a decrease in radius from 3–4 to 1μ during evaporation, was demonstrated. 2. Comparative experiments were conducted on the influence of certain relatively nonvolatile surface-active substances in various concentrations upon the rate of evaporation of water drops. 3. The presence of surface-active substances slows down the evaporation of water drops substantially more than that calculated according to the decrease in the vapor tension above the solutions according to Raoult's law for the same concentrations. 4. It was hypothesized that the deceleration of the evaporation of drops is a consequence of a change in the coefficient of evaporation on account of coating of the drop with a monolayer of the surface-active substance.