ABSTRACT
Rutherford shows that the radiations from the naturally radioactive bodies and also the excited radiations include some rays of an extremely penetrating character, which are able to pass through great thicknesses of matter. The excited activity obtained from the atmosphere is very similar in character to the excited radiations from thorium and radium, it was thought possible that some penetrating rays might be given off from the surface of the earth and walls and rooms on which excited activity from the air is distributed. The rate of discharge of a well insulated gold-leaf system served as a measure of the ionization. The effect of placing metal screens outside the testing vessel was observed. Screens of thickness of 2mm. The results show that about 30 per cent of the ionization inside a closed vessel is due to an external radiation of great penetrating power.
