490 



Mr Hughes, On the Mobilities of the Ions 

 Table IV. lonisation hy X-rays, 



The results given in these tables are plotted in fig. 4. The 



third column in Table IV is copied from Table III for comparison 

 with the second column and the outstanding differences are given 

 in the last column. From these results, it may be concluded that 

 the mobilities of the positive ions produced by ultra-violet light 

 and by X-rays are identical. 



