34 Experiments with the Elementary Voltaic Battery. 
that a close attention to these circumstances becomes necessary in 
all experiments with the elementary voltaic battery. Entertaining 
this opinion, our attention was particularly directed to the phenom- 
ena displayed by different modifications of this arrangement, as de- 
tailed in Vol. xxvii. No. 1. of your valuable Journal; by the Messrs. 
W.and H. Rogers. Strongly impressed by the novelty of some of 
their observations, we determined to engage in a series of analogous 
experiments, modifying and extending them as the circumstanses 
seemed to suggest. 
The galvanometer which we used throughout all our experiments, 
as a measure of electrical effect, was similar in every respect, to that 
described by the Messrs. Rogers, and the solution in which the 
plates were immersed consisted of sixty parts of water, and one of 
sulphuric acid, by weight. 
1. The first observations which we made, had reference to the 
relative importance of the two metals zinc and copper, in the galva- 
nic element; and these closely corresponded with those made by 
the above named gentlemen. 
In order to guard against any sources of error which might arise 
from the immersion of additional fresh surfaces at different depths, 
and also the moistened surfaces when successively withdrawn, we 
preferred using separate pieces of the requisite size, so as to admit 
of entire immersion, and the results were the following. The first 
column indicates the successive intervals of time, elapsing from the 
first moment of immersion of the plates, to that at which the angu- 
lar deflection is observed. 
Copper 4 sq. in. surface. Copper 2 sq. in. surface. 
Zane HQ ee Lime yA ics fe 
YY 50° Ae ei AP: VY 338° bY) 25P 
af AS eee 9° 638 9 OF repeated 9” 9h 
By Adah ae! pabsinudl a 24. 10., ned 
Bo il J 5’ repose. 4, 95 av aq | > Tepose- 4, 9g 
2. It will here be seen that a much greater effect is produced by 
a large copper than a large zinc ; but in order to compare these re- 
sults with those obtained by Messrs. Rogers, with the use of slips 
immersed to different distances, we repeated their experiments, but 
in such a manner as to avoid the error arising from the constantly 
progressive decline, which followed successive immersions. 
From what follows, it will be noticed that a real, though slight, 
augmentation of effect is produced by a considerable increase of 
zinc surface, the copper remaining constant, 
