Temperature upon Photo-electric Effects in Higli Vacuum. 191 



atomic disintegration because o£ resonance, than with that 

 of absorption by free corpuscles of the energy of the incident 

 light. 



In view. then, of the strength of the arguments in favour 

 of Lenard's point of view, and in view of the fact that all of 

 the recorded measurements upon the effect of temperature 

 upon photo-electric phenomena, save only those cf Elster and 

 Geitei. are incapable of a positive interpretation because of 

 the failure of the experimenters to eliminate -econdary effects 

 due to the medium, while even Elster and GeitePs experi- 

 ments were made only upon one metal, and one which has 

 a melting-point only slightly above the temperature at which 

 the experiments were performed, it was decided to reinvesti- 

 gate de novo the effect of temperature upon photo-electric phe- 

 nomena, making all observations in a very high vacuum, and 

 extending the experiments to a considerable number of metals. 



3. Hie Vacuum. — On account of the contaminating in- 

 fluence on the mercury of the usual rubber tube which 

 connects the two reservoirs of a mercury pump, and also on 

 account of the fact that air slowly leaks into the vacuum 



Ficr. 1. 



fertt 



through this tube, this form of tube was discarded altogether 

 after considerable fruitless experimenting with it, and the 

 vacuum was produced with the pump which is shown in 

 fig. 1. This pump possesses no essentially new elements, 



