ABSTRACT
This chapter examines the ionization and excited radioactivity that are produced in air by utilizing a sensitive quadrant electrometer. The simplest method of obtaining a large amount of excited radioactivity from the air is to expose a long insulated wire charged to a high negative potential in the open air. After exposure for several hours the wire is removed and wound on a frame, or in the form of a flat helix. The excited radiation from the air decays with the time in a manner similar to the excited radiation from thorium and radium, but at a different rate. A large number of experiments were made on the effect of atmospheric conditions on the amount of excited radioactivity from the air. Most of the experiments were made during the Canadian winter, when there was about two feet of snow over the ground. The prevailing wind was from the north, and had been carried over snow-covered lands.
