during Absorption of Electrons by Different Metals. 407 



by the former experiments on platinum. We believe that 

 we have discovered the main cause of this inconsistency but, 

 so far, unfortunately, we have not succeeded in regulating it. 

 The cause seems to lie in an instability in the thermionic 

 emission of osmium itself, and we are investigating the 

 phenomenon in detail in the hope of being able to control it. 

 The experiments which follow were carried out, so far as we 

 are able to judge, in the same way and under the same con- 

 ditions as those previously made with platinum. In view of 

 the considerable range of the value of the effect for each one 

 metal, and also of the peculiar effects first observed when 

 experimenting with iron (see below), we shall only give the 

 final numbers obtained in each case and shall omit the details 

 of the measurements which led to them. 



In every case, the strips used were of the purest specimens 

 of the metal obtainable. The gold, silver, palladium, copper, 

 and nickel were obtained as pure from Messrs. Johnson, 

 Matthey & Co., London. This specimen of copper was 

 compared with one rolled from commercial magnet wire, and 

 did not exhibit any notable difference. The aluminium was 

 rolled from commercial aluminium wire and then cut by hand, 

 and the phosphor bronze was a strip such as is used for 

 galvanometer suspensions. 



As a rule, a considerable number of experiments were made 

 on each material. The final results of all those which 

 appeared to be satisfactorv are given in the following 

 table :— 



Metal. 



Corrected Values of <p. 



Volts. 



Mean. 

 Volts. 



Weighted j 

 mean. ■ | 



Volts. ; 



Gold 



Nickel 



654, 7-16, 6-83, 8-04, 7-36, 6-16. 



5-19, 5-38, 5-61. 



7-36, 7-16, 6-86, 6-86, 576, 701. 



5-82. 



6-04, 5-44. 



5-06, 5-83, 4-1G, 5*46, 5*26. 



7-6, 6-9, 5-3, 7-9, 8*6. 



4-95 4-18 4-32 4 # 85 5*54 5-44 



7 01 

 5-39 

 G-84 

 5-82 

 5 72 

 515 

 74 



■d-.QQ 



7 26 



53 



7-1 



56 



__ 



Copper 



Phosphor Bronze ... 

 Palladium 



Silver 



Aluminium 



Iron (low) 



Iron (high) 



6-27 (Vf>8 Pr4°) 7-5° «' ■"•> 











