Abstract
MESSRS. ELSTER AND GEITEL have published an important paper in the Physikalische Zeitschrift (No. 9, pp. 522-530), “Ueber die radioaktive Emanation in der atmospharischen Luft.” They find that the abnormal conducting power of the stagnant air-of cellars and caves, and the amount of induced radio-activity which can be obtained from such air upon a negatively charged rod suspended in it vary greatly in different regions. In some places such air is no more active than ordinary atmospheric air. Air sucked through a pipe of which one end is buried in the ground is generally active, like the air of most cellars and caves; tests of the activity of samples of such ground-air from different localities showed great variations, some being no more active than ordinary air. The activity of ground-air falls off at a rate comparable with the rate of decay of the radium eman. If a portion of the soil of a region in which the ground-air is radio-active is isolated, it gives to a volume of air in contact with it abnormal conductivity which reaches its maximum in a few days. The soil retains this power for many months at least. The phenomena are all most readily explained by supposing that substances, which have the power of producing a radio-active emanation like that of radium, are distributed in varying amount among the materials composing the soils of different regions. In the latter part of the paper is an account of some interesting observations on the dependence of the radio-activity of atmospheric air upon meteorological conditions. The increase of the activity of the air which generally accompanies a fall of the barometer is attributed to the escape of ground-air into the atmosphere.
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The Ionisation of Atmospheric Air . Nature 69, 154–155 (1903). https://doi.org/10.1038/069154a0
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DOI: https://doi.org/10.1038/069154a0