RESIDUAL CHARGE OE THE LEYDEN JAR, 
603 
(&) Let the charging last during a shorter time r', then discharge and insulate from 
time to time as in (y) : — 
(V 
( s ) Charge during time r’, and reverse the charge for time r" before discharging : 
d £=XW(t)-2t(T''+t)+W+T l '+t)l ( 8 ) 
III. Glass No. 1. — This glass is a compound of silica, soda, and lime. In a damp 
atmosphere it “ sweats,” the surface showing a crystalline deposit easily wiped off. For 
a soda glass it is very white. Density 2’46. 
When the flask was mounted, connected with the electrometer, the image from 
which was deflected 70 divisions by one Daniell’s element, and insulated, it was found 
to steadily develop a negative charge, amounting to 11 scale-divisions in 10 seconds, 
and increasing to a maximum of 25 divisions. The cause of this the author cannot 
explain. Two other flasks of the same glass behaved in a similar manner — in one case, 
with the thin flask of § I., the charge rising to 40 divisions, with the thick flask to only 
15 divisions. No sensible effect of the same kind was noticed with any other glass. 
The effect does not appear to be due to the connecting wires (for these were repeatedly 
removed and replaced by fresh ones), nor to difference between the acid within and that 
outside the flask, as this also was changed. 
Experiment a. — The flask was charged to 500 divisions for half an hour, insulated, 
and the potential observed after 5, 10, 15, 20 seconds. The mean of several experiments 
gave for these times 372, 275, 216, 170: hence the loss in 5 seconds is about 25 per 
cent. ; and from this we may readily deduce since the percentage of loss is not mate- 
rially different in the second interval of 5 seconds, B=3’4, the minute being unit of 
time. 
Experiment (3.— An attempt was made to estimate ^(O). The charging lasted one 
second. In two seconds from insulation the charge fell from 500 to about 330, which 
gives \J/(0) certainly greater than 10 - 2. This can, of course, only be regarded as the 
roughest approximation. 
Experiment y. — The flask was charged positively for about 19 hours with 48 elements, 
the electromotive force of which is represented by about 3360 scale-divisions. It was 
then discharged, and at intervals insulated for 10 seconds, and the residual charge deve- 
loped in that time observed. Column I. gives the time in minutes from first discharge 
to the middle of each 10-second period ; II. the charge developed in ten seconds ; 
III. the estimated value of \{/(£) — B, obtained by correcting for the negative charge 
which it was found this flask took in 10 seconds, and dividing by 3360. 
These results are certainly much below the true values, for the image moved over the 
scale much more rapidly in the first than in the second five seconds ; but their ratios 
are probably fair approximations. 
