324 Mr. R. T. Beatty on the Production of Cathode 



changes when these particles are absorbed completely by air 

 and hydrogen respectively. 



For each radiation a complete curve was first obtained 

 with air : then the air was completely pumped out, the final 

 exhaustion being effected by means of a charcoal tube sur- 

 rounded by liquid air. Hydrogen was then admitted and 

 another curve obtained. The results for Fe 7 Zn, Sn are 

 shown in figs. 4 ; 5, 6 (PI. V.). 



Preparation of the Hydrogen. 



Special care was taken to obtain pure hydrogen, as a very 

 small percentage of impurity will increase the ionization in 

 it perceptibly. Pure zinc and sulphuric acid (Kahlbaum) 

 were used, the acid being diluted with ten times its volume 

 of distilled water, the mixture being then boiled to expel 

 dissolved air : a little copper sulphate was also added. The 

 reaction took place in a special form of kipp of small volume, 

 the greater part of which was kindly constructed for me by 

 Mr. A. LI. Hughes. The gas was passed through KHO, and 

 stored over pure H 2 S0 4 : it was then admitted to the ionization 

 vessel through phosphorus pentoxide and through a spiral 

 glass tube immersed in liquid air. 



Tables I. and II. show the results obtained with air and 

 hydrogen. 



Table I. — Air. 



Radiator. 



t. 



X. 



C. 



T. 



130 

 124 

 11-4 

 143 

 139 



Fe 



•00S04 



•0135 



•0164 



•0255 



•1762 



87 2 

 519 

 427 

 27-43 

 397 



•149 

 •239 

 •268 

 •522, 

 3v F 



Cu 



Zn 



As 



Sn 



Table II. — Hydrogen. 



Radiator. 



t. 



X. 



R. 



H. 



Fe 



•0410 

 •0733 

 •0909 

 1-37 



17-05 



955 



7-71 



•51 



5-12 

 5-44 

 5-54 

 7-79 



1-01 



100 



•98 



100 



Cu 



Zn 



Sn 





