94 
MR. GROVE ON THE GAS VOLTAIC BATTERY. 
with a voltameter (fig-. 7)> the tubes of which are of the same size as those of the 
battery. 
In the form last described (figs. 4 and 6), the tubes were all as nearly of the same 
size as could be procured; they contained each about 1^ cubic inch; in the first 
form (figs. 1 and 3), the portion o, r of the narrow tube contained cubic inch, and 
the portion h, r' of the wide tube contained 2^ cubic inches. A portion of the appa- 
ratus with which I wrought was constructed by my order for the London Institution, 
and another portion belonged to Mr. Gassiot, and was by him very kindly placed at 
my disposal for the purpose of these experiments ; had it not been for this valuable 
addition, I should have been obliged to make all my experiments on a much smaller 
scale ; they would have taken more time and been by no means so satisfactory. 
As I have already stated, a third form has occurred to me while writing this paper, 
which I think in many respects more advantageous than either of the two preceding, 
and which, as it may be some time before I can experiment with it myself, I will here 
describe for the benefit of those who are differently situated. One cell of it is shown 
in fig. 8 : a, a, is a Woulfe’s bottle with three necks ; in the centre neck is fitted a 
glass stopper, b ; in the other two the tubes o, li fit accurately by means of glass 
collars (c c. fig. 9.) welded to them and ground on the outside ; the platinum is her- 
metically sealed into the tops of the tubes, which may be charged in a similar manner 
to fig. 1. By immersing this apparatus in the water-trough, each tube with the gas 
it contains may be detached and examined separately, but its principal advantage is, 
that by slightly greasing the stopper and collars it may be made perfectly air-tight, 
which, for reasons that will be apparent in the course of this paper, is a most material 
point. This apparatus, moreover, being entirely composed of glass and platinum, 
concentrated acid, alkaline or other corrosive solutions, may be used as the electrolyte, 
without damaging the apparatus or introducing foreign matter. 
In the experiments I am about to describe, the results were generally tested by 
chemical action, as manifested by the electrolysis, either of iodide of potassium or of 
water. I had at my disposal a highly sensitive astatic galvanometer, but I found 
such slight local actions disturb it, that a range of test experiments was in each case 
necessary to eliminate the true battery action from the accidental currents ; and with 
all the pains that could be bestowed upon it, the results were less definite and trust- 
worthy than those obtained with the iodide. 
I may here state also, that, although with the battery described in my original 
paper when charged with oxygen, hydrogen and dilute sulphuric acid, I could not 
succeed in perceptibly decomposing water with less than twenty-six cells, yet the new 
arrangements, from their superiority in size and construction, were capable, when 
charged with the same gases and electrolyte, of decomposing water with four cells ; 
and a single cell would decompose iodide of potassium. 
Experiment 1. — Ten cells charged to a given mark on the tube with dilute sulphuric 
acid, sp. gr. T2, oxygen and hydrogen, were arranged in circuit with an interposed 
