112 
MR. GROVE ON THE GAS VOLTAIC BATTERY. 
spheric air in solution, which had escaped to fill the vacuum. When the stopper was 
taken out the liquid rose suddenly in the hydrogen tube 2 2 cubic inches, giving the 
equivalent of the oxygen in the tube and in solution. It is very possible that this ex- 
periment repeated might sometimes exhibit an evolution of hydrogen in the oxygen 
tube arising from the escape of the nitrogen of the atmospheric air in solution, and 
acting as in experiment 29, but I have not seen this effect take place. It should be 
distinctly understood, that in all the experiments mentioned in this Postscript, except 
the first part of experiment 28, single cells only were used. 
Upon the theory of the experiments 29 and 30 I will venture no positive opinion. 
That gaseous hydrogen should abstract oxygen from hydrogen, without the latter 
forming any other combination, is a fact so novel, that any attempted explanation is 
likely to prove premature. If, contrary to the views of Dalton, we suppose that 
gases when mixed are held together by a feeble chemical affinity, then we may say 
that the affinity of the nitrogen or carbonic acid for hydrogen produces the effect ; 
the affinity of the oxygen of the water, being balanced between the hydrogen in the 
liquid and that in the tube, would enable the resultant feeble affinity of the nitrogen 
for hydrogen to prevail ; but on this supposition, why does not oxygen produce an 
analogous effect? Its tendency directly to combine with platinum may indeed be 
regarded as an opposing force, but this tendency is by many considered hypothetical. 
On the other hand, it may be called an effect of contact; but this, unconnected with 
a chemical theory, presents no other idea to the mind than the fact itself presents, it 
furnishes no link by which we may extend the phenomena. I therefore, until a better 
theory be found, should be inclined to adopt the former view, and to regard mixed 
gas as in a state of feeble chemical union, the more especially as throughout nature 
we find no absolute lines of demarcation, though for conventional reasons we are 
obliged to adopt them ; there must be many cases in which it is difficult, if not im- 
possible, to draw the line between mechanical mixture and chemical combination. 
In conclusion, I would say with regard to the whole of the experiments contained 
in this paper, that a longer time and more experience may give positive results in 
cases where I have only obtained negative ones ; it is far from impossible that since 
curious solid combinations are formed by slow electrical currents, as in the experi- 
ments of Crosse and Becquerel, so novel gaseous or liquid products may be ob- 
tained by the long-continued voltaic action of gases and liquids. This time alone 
can show. 
For previous experiments and theories on the combination of gases by platinum, I 
may refer to Dobereiner’s paper, Phil. Mag. Oct. 1823, in which I find he expresses 
an opinion that it is a voltaic effect ; to the papers of Dulong and Thenard, Annales 
de Chimie, tom. 23 and 24, and to Faraday’s Experimental Researches, Series 6. 
The various experiments on polarized electrodes of Ritter, Faraday, De la Rive, 
Becquerel, Matteucci, and Schcenbein, are also in point. 
