Surface Leakage Resistance of Glasses

Abstract

Glass rods for lamp and tube of about 4mm in diameter were provided with two electrodes at the distance of 30-40mm, and the apparent resistance, which is equivalent to the combination of volume and surface resistance connected pararell, were measured by the method of filament electrometer or direct deflection.In the first series of the experiment the specimens were washed by loundry soap and city water. In the season of high humidity (summer) the apparent resistance has changed after the preparation of the specimens showing a clear corelation with relative humidity. After half a year, and in the season of low humidity (winter) some glasses showed comparatively high surface resistance, keeping the apparent resistance at a constant level, being very near to the volume resestance. In the glasses of higher volume resistance, however, the change of surface resistance due to the change of humidity was clearly observed. After a year a lot of specimens gave the apparent resistance of as high as 10-100 times under the same atmospheric conditions.In the second series of the experiments the apparent resistance of the fresh specimen was compared with those aged a year and those treated with dilute hydrofluoric acid. It was observed that the apparent resistances of above three kinds of the specimens showed the similar trend of the change with the atmospheric conditions, and the initially quite different of numerical values came up to one and the same value with the laps of time.In the last series of experiments the apparent resistance of the specimens washed with, acid, alkali and salts was measured in the cell, to which, after evacuation, water vapour was introduced up to a certain saturation pressure. It was confirmed that the characteristic properties of apparent resistance vs. vapour pressure varied remarkably with the method of surface treatment.