508 
ME. H. xV. WILSON ON THE ELECTRICAL CONDUCTIVITY 
where E is the P.D. between the electrodes expressed in terms of the E.M.F. -per 
cell used (I'80 volts). When E is less than about 5 the drop at the negative 
electrode is zero. 
The following table shows this :— 
E. 
0-873E - 4-4. 
Negative drop observed. 
GO 
48-0 
48-5 
40 
30-5 
30-0 
20 
13T 
16-0 
10 
4-3 
6-0 i 
5 
0-0 
0-0 
Diagram No. 8 shows two curves obtained with the electrodes 5 centims. apart, 
the lower electrode Ijeing still in the same position as before. 
Diagram No. 8. 
In this case the drop of potential at the lower negative electrode did not become 
appreciable until about GO cells were used. Moving up the upper electrode to the 
colder parts of the flame rapidly increased the P.D. at which the negative drop 
appeared. Thus at 8'8 centims. above the lower electrode there was no negative 
drop even when 400 cells were used. 
When the upper electrode was charged negatively the character of the potential 
curves was completely changed. In this case nearly all Tie fall of potential occurred 
near to the upper negative electrode. Diagram No. 9 shows two curves got with the 
electrodes 5 centims. apart. Diagrams 10 and 11 each show two curves, one with 
the upper electrode positively and the other with it negatively charged. 
