116 REPORT—1890. 
Now, we have seen that with the galvanometer as I used if, if y is the 
throw produced by the passage of a quantity Q, then Q=y x 10-19, 
The battery consisted of 36 small storage cells, which, when fully 
charged, had an E.M.F. of about 75 volts, so that 
tp x NOP: 
Also, C,='021 microfarad 
a ere ce 
Hence, with these numbers, 
Oe. Rois Ea 
Gar RY Hal hea. 
or, writing it as a correction to ¢,, 
__Cy Ro 
10) 
1 Ry 
Y {7 + F2\19-18 
7,(1+22)20 
Examples of the method of applying this correction will be given 
shortly. 
It will be noticed that a leak in one of the condensers may be cor- 
rected for in the same way. For, suppose the mica condenser to leak, 
then a quantity Q’ of positive electricity passes through to the plate A,, 
while the battery current is on, and the condition that the galvano- 
meter should not be deflected is, 
Co Ro i—C, Ry 1=Q! 
the same equation as previously. 
There will, however, be this difference: on depressing the key kK after 
breaking the battery circuit, a positive charge will in both cases pass 
from a to B through the galvanometer; if this charge be due to absorp- 
tion, there will, when the key is again depressed after an interval, be a 
current through the galvanometer in the opposite direction; while if the 
first charge be due entirely to a leak, there will be no effect when the key 
is the second time depressed. In practice, the leak and the absorption 
may exist together either in the same or different condensers. In the 
second case the leak will tend to produce opposite effects to those caused 
by the absorption; the quantity Q’, however, increases nearly in the 
ratio of the time of charging, while Q increases for the first few seconds, 
but soon reaches a maximum and then remains constant. 
These considerations are illustrated by some experiments in which the 
condensers I. and II. were compared with various mica condensers. The 
battery key was in each case made for 30 seconds; it was then broken, 
and the galvanometer key was made for an instant. The resulting throw 
was the sum of those due to (1) the leak in the mica condenser, (y), say ; 
(2) the absorption in that condenser, (a), say; and (3) the leak in the 
air condenser, which produces an effect in the opposite directiom 
(—y'), say. 
After about 30 seconds more the key was again depressed; the 
resulting throw is due to the absorbed electricity which has again leaked 
out, and will give us —a. 
The following table gives the results; each observation entered is the 
mean of three or four. 
ae 
