Current. 
304 Mr McClelland, On the Action of Incandescent Metals 
6. The numbers given below refer to experiments when the 
c is yq mm. 
Wire negative 
volts 
Current in arbitrary 
units 
40 
57 
80 
68 
160 
80 
240 
86 
320 
94 
400 
100 
Wire positive 
volts 
Current in arbitrary 
units 
40 
7 
80 
13 
160 
20 
240 
32 
320 
54 
400 
100 
As mentioned previously the current is always very much 
greater when the wire is charged negatively ; the above numbers 
are not to scale in the two cases. The curves referring to these 
numbers are given in Fig. 6. The current when the wire is 
0 40 80 120 160 200 240 380 320 360 400 
Volts. 
Fig. 6. 
charged negatively does not increase rapidly with the higher 
potential, which means that at this pressure the velocity of the 
negative ions even with small voltage is such that ionisation is 
