﻿Thermionic Currents from Tungsten. 8 1 3 



or not. This was true even after the filament was finally 

 burnt out. All the observations are shown in fig. 4, for 

 comparison with those of Lamp 3. 



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Taken together these two experiments show that the initial 

 negative thermionic current is very much less than that 

 obtained on subsequent heating. The actual difference would 

 be more obvious if the currents, instead of their logarithms, 



