506 
MR. H. A. WILSON ON THE ELECTRICAL CONDUCTIVITY 
the upper electrode, partly because, owing to its wider mesh, it lost heat less readily 
by conduction to the brass disk supporting it. 
Diagram No. 6 shows the relation between the current and the distance between 
the electrodes when the lower electrode is positive and kept fixed for an E.M.F. of 
70 volts per centim. of distance between the electrodes. 
O 12 3^3 cms. 6 
The current was always greater when the hotter electrode was negative than when 
it was positive, except when the electrodes were very near together, so that a very 
great electromotive intensity coidd be applied. 
The following table gives some of the currents observed showing this :— 
E.M.F. 
Height of Lower 
Electrode above 
the Flame tube. 
Distance between 
the Electrodes. 
Current. 
(100 = 4-7 X 10”® amjtere.) 
(1) 
Lower + 
(3) 
Lower - 
volts. 
centims. 
centims. 
335 
5-6 
1-28 
75 
233 
100-5 
5-6 
1-28 
36-5 
198 
330 
5-6 
2-20 
30 
233 
370 
5-6 
6-2 
10 
18 
1-2b 
5-6 
0-3 
407 
235 
350 
3-65 
3-35 
16 
355 
175 
3-65 
3-35 
10-5 
315 
Tlie theoretical l)eariiig of the results descril)ed in 
discussed in Section 7. 
this section of the })aper is 
(3.) The Fall of Potential hetween the Electrodes. 
•% 
To examine the fall of })otential along the fiaine between the electrodes, a horizontal 
insulated platinum wire was put in the flame, and its potential measured either by 
means of a quadrant electrometer or l)v connectlno- It throuu’h a iralvanometer to a 
