380 



Prof. C, Sheard on the 



and practical equality of positive and negative potential 

 currents continued for two hours or more. Plenty of salt 

 remained in A at the end of the experiment. The positive 

 and negative current- time relations for A were identical 

 in form with those given in curve 1, fig. 3. The values 

 given for tube A in Table IV. are in excellent agreement 

 with Schmidt's results. The ionization effects in the unsalted 

 tube, however, showed marked contrasts with those obtained 

 in the salted tube. The magnitude of both negative and 

 positive potential currents in B in comparison with those in 

 A (see Table IV.) is a most noticeable feature. Both 

 currents in A had about the same value at corresponding 

 times : in the unsalted tube the ratio of the initial negative 

 maximum to the initial positive maximum was 7 : 1. These 

 experiments fully confirm the statemeut that the ionization 

 is partly an ionization of the vapour. 



P = lcm. 



Table IV. 

 T = 358-363° C. 1 division = 10 " 10 ampere. 



Time. 

 (Min.) 



Tube A. 



Time. 



(Min.) 



Tube B. 





+ - 

 65 



101 

 133 



30-3 

 2-8 



57 

 1-26 



1-83 

 061 



0-83 

 043 



0-47 

 0-38 



039 



0-31 



0-37 



0-35 



0-35 



0-42 



0-41 



6 



+ 

 2347 



17745 

 3547 



16198 

 1183 



12103 

 819 



9100 

 637 



7462 

 455 



5187 

 192 



2366 

 57 



910 

 27 



544 

 3T 



83 

 2-3 



48 

 0-78 



7-4 

 07 



1-4 



7 



10 



11 



12 



13 



14 



16 



17 



19 



20 



22 



23 



25 



28 



26 



29 



32 



31 



37. 



35... 



43 



38 



53 



48 



57 



50 



71 



60 



62 



67 



69 



86 



77 



100 



90 



98 



102 



104 



121 



155 



157 



123 



166 



169 





1 



Several attempts were made to carry out similar experi- 

 ments with this form of apparatus at temperatures above the 

 melting-point of cadmium iodide. Enormous irregularities 



