ABSTRACT
This chapter describes an account of some experiments made to determine the maximum penetrating power of the X-rays excited by high voltages in a Coolidge tube, using lead as the absorbing material. In these experiments, the absorption of the X-radiation by lead has been examined over a very much wider range of intensity and of thickness of absorber than in the original experiments of Rutherford, Barnes, and Richardson. The well-insulated Coolidge tube was placed inside a large lead box, and the X-rays, issuing through a rectangular opening in the box, passed into the measuring vessel which was placed close to the opening. In order to avoid disturbances due to stray radiations, the windows of the electroscopes were of thick plate-glass and still further protected by lead extensions. The maximum voltage applied was about the limit of capacity of the induction-coil under the working conditions.
