High Frequency Conductance of Pyrex Glass in the Presence of Vapors

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Abstract
The electrical conductance of ``Pyrex'' brand glass 774 was measured at frequencies between 40 kc and 1000 kc in the presence of ethyl alcohol vapor and water vapor. Data were taken at 50°, 65°, 79° and 107°C. The relations between conductance, degree of saturation, and frequency were found to be of the same form at all temperatures. There is a distinct discontinuity in the curves of conductance vs. frequency at about 500 kc. Vapor pressures of alcohol up to 85 percent of saturation cause no change in the conductance of the test piece. However, above this degree of saturation the conductance increases rapidly with pressure, becoming very high if condensation occurs. Conductance decreased with increasing current unless the test element was aged in the vapor several hours. Surface conductivities for both alcohol and water vapor are computed. Those for water vapor agree, well within the limits of error, with the results found by Yager and Morgan. An unexplained resonance effect occurred when high currents were used to measure the conductance while the test element was in the presence of small amounts of either alcohol or water vapor. The effect shows the double resonance peak and many of the other characteristics of close coupling between oscillating circuits. However, the effect is in some way due to the energy absorbed in the test element in the presence of a minute amount of water or alcohol since either an increase or decrease of pressure will cause the disappearance of the phenomenon. It was impossible to produce the effect by the substitution of any combination of capacity and artificial leak.

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