Rontgen rays and the radiation from radio-active substances. 361 



Experiment 6. 



Time in sec. 

 required by 

 radium-rays 



Time in sec. 



required by 



uranium-rays 



Time in sec. 



required by 

 radium- and 

 uranium-rays 



CO 



CD !>-. 



3 o3 

 TS *? 



CD Fj 



60 « 

 o3 .3 



03 o3 

 a> i-< 



^ o 



Leakage due 



to 

 uranium-rays 



3 



Leakage due 

 to radium- and 

 uranium-rays 





123-6 



137-5 



64-2 



0-00809 



0-00727 



0-0153 



0-0156 



1-02 



122-7 



138-8 



63-0 



815 



721 



154 



159 



1-03 



121-4 



138-4 



63-6 



824 



723 



155 



157 



101 



124-3 



134-2 



65-5 



805 



745 



155 



153 



0-99 



124-8 



132-6 



63-4 



801 



754 



156 



158 



101 



123-2 



143-2 



65-8 



812 



698 



151 



152 



101 



122-4 



138-7 



65-5 



817 



721 



154 



153 



0-99 



124-5 



139-5 



66-4 



803 



717 



152 



151 



0-99 



122-0 



139-5 



63-0 



820 



717 



154 



159 



103 



129-8 



132-7 



68-0 



770 



754 



152 



147 



Meanl 

 value} 



0-97 



1O0 



From this table we see that the ionization due to radium and 

 uranium oxide acting simultaneously is equal to the sum of the 

 ionizations due to them acting separately. 



§ 5. Thirdly, I tried the combination of X-rays and uranium- 

 rays. Since the experiment could not be conveniently carried out 

 by the old arrangement, a new ionization vessel was constructed. 



The vessel is a very short cylinder 14 cm. in diameter and 

 6 cm. in height. 



Its top has a hole at the centre through which a brass rod 

 passes into the vessel in the same manner as in the previous 

 cases. The lower end of the rod carries a wire net in the form of 

 a circle 10 cm. in diameter in a horizontal position. 



The distance of the net from the base of the vessel is about 

 1 cm. The base itself is not soldered to the vessel, but only 

 pressed against it by means of two brass springs, so that it can be 

 taken away at will. The central part of the base is marked for 

 the reception of a circular metallic disc 10 cm. in diameter, which 

 is covered with uranium oxide leaving a blank margin. 



In consequence the ionization current due to the uranium 

 oxide mainly takes place between the oxide and the wire net. 



When only X-rays were acting, I put instead of this disc 

 another disc of exactly the same form and size, but without 

 uranium oxide. The side wall of the vessel has an aluminium 



