Evaporation of Mist Particles and its Bearing on Air Sterilization

Abstract

DURING the determination of particle size distribution in various germicidal aerosols, a qualitative correlation was noticed between the biological activity and the persistence of the droplets in the field of the ultra-microscope. The instrument was therefore adapted for the determination of evaporation rates; the disappearance of a selected particle was followed by successive measurements of its fall under gravity, its position being restored after each by a screw which displaced the cell contents upwards. Provisions were also made to follow the particle throughout its wanderings in the horizontal plane. It was then possible to watch a single particle for an indefinite period limited only by its complete disappearance or by physical fatigue in the observer.