Positive Emission Currents from Hot Platinum. 499 



'decay a few per cent. After the stage showing saturation 

 ."between 100 and 400 volts had appeared, this form of 



10 



Fig. 1. 

 20 



30 





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0-25 





















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A, 



400 



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< 



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80 



400 



160 240 320 



Potential (Volts) 

 current-E.M.F. curve apparently persisted indefinitely. The 

 only change observed subsequently, on heating at constant 

 temperature, consisted in a uniform decay of the total 

 •current at all voltages. 



2 L 2 



