120 Proceedings of Royal Society of Edinburgh, [jan. 16, 
t 1 2 4 8 12 
x{ohserved\ 83 53*5 38-6 27*3 22-3 
xicalculated), 81-9 55*1 37*9 26-5 22*9 
the coincidence again being close, though not so good as before. 
The value of the constant b shows that in at most twenty 
minutes (the unit in terms of which the constants are calculated 
being one minute), the quantity practically reaches its final 
value ; that is, the resistance has practically reached its final 
value. This is not in accordance with the idea on which the above 
investigation was based. But the close agreement of calculation 
and experiment renders it probable that the resistance may increase 
more rapidly when polarisation is going on, than when the plates 
are merely having oxygen slowly deposited on them. I have 
remarked in my paper on transition-resistance, that certain experi- 
ments I made seemed to indicate this. To obtain definite information 
on the point, I have used a dead beat galvanometer, so that the 
reading of the deflection could be taken at an interval of five seconds 
after starting the current. In all other points the arrangement of 
the apparatus was the same as in the previous experiments ; that 
is, the platinum electrodes 60 square centimetres in area, which 
di]3ped into a dilute solution of sulphuric acid, were connected 
with the terminals of the galvanometer. A single tray-Daniell cell 
was placed in circuit when required. When the cell was joined in, 
readings were taken at intervals of five seconds for a short time. 
Then the plates were polarised until the reverse electromotive force 
was as nearly as possible equal to that of a Daniell cell, after wliich 
the battery was thrown out of circuit, and the readings during 
discharge of the plates were taken as before. 
Experiment la. 
Time in seconds, 
5 10 
15 
20 25 
30 
Deflection during charge, 
8 5-7 
4-6 
4 3-5 
3*2 
Deflection during discharge, 
... 3-64 
2-94 
... 2-64 
2-34 
Experiment 2a. 
Time in seconds. 
5 
10 
15 
20 
Deflection during charge, 
9-03 
7*03 
6-03 
5-43 
Deflection during discharge. 
4-7 
3-8 
3-3 
3-2 
