ABSTRACT
In 1897, Schmidt found that the compounds of thorium had the same property as uranium. This chapter presents an extension of the investigation to the radiation emitted by thorium and its compounds, and a comparison of the two types of radiation. The intensities of the radiations were compared electrically by measuring the rate of discharge of electrification produced by the rays. A layer of the radio-active substance was uniformly spread on a small platinum plate which rested on the top of a larger brass one. The phenomena of electrical conduction produced by thorium radiation are strictly similar to those produced by Roentgen rays and uranium radiation, and obey the same laws. For high pressures of air, thorium oxide behaves differently from uranium, but the difference is probably closely connected with the action of currents of air on the intensity of the radiation.
