Measurements of the Electrical Conductivities of Air over Hot Water

Abstract

Measurements of the conduction current between two electrodes in air over recently boiled water have been interpreted by Carlon as indicating that the humidified air became highly conductive and that large numbers of ions were produced in the air after it was saturated with water vapor. These interpretations have been questioned because it is possible that the insulators used in the high-humidity experiments allowed leakage currents to flow and these were treated as though they were conduction currents through the air. We repeated these measurements with the use of a conventional, Gerdien cylinder conductivity-measuring apparatus that had insulators heated to temperatures above the dew point of the water vapor in the air being measured so that the insulators maintained high resistances. The results from the heated Gerdien cylinder experiments contradict the suggestions of high conductivities in humid air, for the measured conductivities of air were repeatedly observed to decrease by about 50% when recently boiled, hot water was brought in contact with the air.