Resonance Potentials for Electrons in Metallic Vapours. 47 



The above values are plotted in fig. 4, V versus 1]X. A 

 straight line passing through the origin is obtained, confirm- 

 ing the quantum relation. The mean value of h obtained 

 either from the curve or the above table is /t=6*55 . 10~ 27 

 erg sec. In obtaining this mean value and in drawing the 



Fig-. 4 



10 



7 - 



•3 5 









i ' ' 



! i ! 



w\ 



1/ i 









i i i 



A i 



A i 









! i I / 



/Cd 



! 









i Y Ha 



! ! /i 















i / 

 i / 





J 



I 











/Ma 







1 



1 









Z ZU 



H 9 







1 

 ! 







^ 





1 



1 



! 



! 





Mq/ 



Aid 







1 





i 



i 





K/ 





\ 



! 









/Tl 





___ 



| 





| 



JO*/ 'A A 



Determination of h by ionization and resonance potentials. 



straight line of fig. 4 each determination was given equal 

 weight. The final value of h = 6'55 . 10 -27 is in excellent 

 agreement with the value of 6*547 . 10 -27 which Millikan * 

 suggests as the most probable value. 



* Phil. Mag. xxxiv. pp. 1-30 (1917). 



