284 Wellisch — Experiments on Active Deposit of Radium. 



Experimental Procedure. 



2. It is unnecessary to enter here into any detailed descrip- 

 tion of the apparatus and the experimental method, as these 

 were in all respects the same as previously described. The 

 essential features of the method were as follows : the emana- 

 tion mixed with any gas was introduced into a cylindrical 

 vessel with a central electrode and remained there under the 

 desired conditions of potential, pressure, etc., until radio-active 

 equilibrium was established. The emanation was then blown 

 out by means of a strong current of air and the amounts of 

 active deposit on the central electrode and on the case were 

 measured separately, the proper corrections being made for the 

 decay of the deposit after the emanation had been removed. 

 The ionization currents were measured by means of an electro- 

 meter which had a sensitiveness of 180 mm per volt. Arrange- 

 ments were made for the addition of suitable capacities when 

 the currents were large. 



Distribution of the Active Deposit in Ethyl Ether. 



3. In this series of experiments the vapor was obtained 

 by evaporation from the liquid ; it was dried by phosphorus 

 pentoxide and admitted into the testing vessel which had 

 previously been evacuated. The ether was then removed till 

 the pressure in the vessel was only a few mm., a fresh lot of 

 ether was introduced as before and this process of fractiona- 

 tion was repeated about five times. In the final stage the 

 ether was introduced through the radium solution and after 

 passage through the drying agent was admitted into the testing 

 vessel. 



The following table exhibits the results obtained for the dis- 

 tribution of the active deposit for various pressures of the ether 

 and for different potentials applied to the case of the testing 

 vessel. 





Table I. 





Pressure 

 mm. 



Potential 

 volts. 



Percentage 

 deposit on 

 central rod 



82 



+ 750 



9-1 



87 



— 750 



9 2 



82 



— 160 



9-6 



88 



— 20 



9'2 



89 



+ 20 



10-0 



89 



-160 



9-2 



93 



4- 4 



10-4 



80 



— 2 



10-4 



87 







10-3 



