152 
PROFESSOR DANIELL ON VOLTAIC COMBINATIONS. 
This is, moreover, not the only point for consideration ; for it is probable that the 
hydrogen accumulated upon the zinc of the reversed cells would exalt its electro- 
motive force, so that — E would be somewhat increased ; and upon making the cal- 
culation upon these amended data the formula becomes 
n E — n' E' — e . mE- ri E' — e 
(n + n') R + r + n' r 1 5 01 n R + n 1 R' + r 
taking in the first formula r' to represent the additional resistance introduced by 
each reversed cell, and in the second R' as the total resistance in each reversed cell, 
and E' the increased electromotive force in each of the same reversed cells. 
In the following calculation E = 1, R = 1, e = 2*85, r = 1*725, E' = 1*1, r' = 0*5. 
It is assumed that r' is a constant quantity, which may be pretty accurately true 
when the copper surface is so large in relation to the zinc as in the present case. 
20 direct, 
1 reversed, 
2 reversed, 
3 reversed, 
4 reversed, 
5 reversed, 
6 reversed, 
7 reversed, 
8 reversed, 
Calculation. 
Experiment. 
20 - 2*85 
17*05 
Cubic inches. 
1 Q* 1 O 
Cubic inches. 
17-5 
20 + 1*725 
21*725 
19 - 2*85 - 1*1 
15-05 
15*57 
15*5 
20 + 1*725 + 0*5 
22*225 
18 — 2*85 - 2*2 
12*95 
13*1 
12*75 
20 + 1*725 + 1*0 
22*275 
17 - 2-85 - 3*3 
10*85 
10*74 
10*5 
20 + 1-725 + 1*5 
23*225 
16 - 2-85 - 4-4 
8*75 
8*48 
8*5 
20 + 1*725 + 2*0 
23-275 
15 - 2-85 - 5*5 
6-65 
6*31 
5*5 
20 + 1*725 + 2*5 
24-225 
14 - 2*85 - 6*6 
4-55 
4-23 
3*5 
20 + 1*725 + 3*0 
24-725 
13 — 2*85 — 7*7 
2-45 
2*23 
1*625 
20 + 1*725 + 3*5 
25-225 
12 - 2*85 - 8*8 
0*35 
0*31 
1*16 
20 + 1*725 + 4*0 
25*725 
The agreement of the experiments with the calculations is not as close as before, 
especially in the lower part of the table, but may I think be deemed satisfactory, 
as a first approximation to the solution of a problem of a most complicated nature. 
The influence of the dimensions of the plates of a voltameter upon the amount of 
decomposition may also be submitted to calculation in the same way. This influence 
will, of course, be most perceptible when a small number of elements presenting a 
large surface is employed ; whereas, when a numerous series is made use of, the di- 
mensions of the electrodes are of little consequence. Some experiments which I 
have made with a large voltameter, kindly lent to me for the purpose by Mr. Gassiot, 
