抄録
The disturbance of the atmospheric potential gradient, caused by the eruption-smoke of the Volcano Aso, was observed in the neighbourhood of the crater. It was found that the disturbance was positive when the volcanic ashes were falling. The negative disturbance was often observed in short durations when the tip of the smoke reached the zenith of the observing spot. The electrification of ashes by the mutual collision was investigated in the laboratory and it was found that the larger particle got the positive electricity and smaller particle the negative.
