Experiments on the Electrical Phenomena produced in Gases by Röntgen Rays, by Ultra Violet Light, and by Uranium

Abstract

§ 1. To test whether or not the Röntgen rays have any electrifying effect on air, the following arrangement was made.A lead cylinder 76 cms. long, 23 cms. diameter, was constructed; and both ends were closed with paraffined cardboard, transparent to the Röntgen rays. Outside the end distant from the electrometer (see diagram 1) a Röntgen lamp was placed. In the other end two holes were made, one in the middle, through which passed a glass tube (referred to below as suction pipe) of sufficient length to allow the end in the lead cylinder to be put into any desired place in the cylinder. By means of this, air was drawn through an electric filter by an air pump. The other hole, at a little distance from the centre, contained a second glass tube by which air was drawn through india-rubber tubing from the open-air quadrangle outside the laboratory.In one series of experiments the end of the suction pipe was kept in the axial line of the lead cylinder at various points 10 cms. apart, beginning with a point close to the end distant from the Röntgen lamp.In every case the air drawn through the filter was found to be negatively electrified when no screen or an aluminium screen was interposed between the Röntgen lamp and the near end of the lead cylinder. The air was found not electrified at all, or very slightly negative, when a lead screen was interposed.