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LXXII. On some Phcenomena of the Voltaic disruptive Dis- 
charge. By W. R. Grove, Esq.<i M.A., M.R.S. 
My dear Sir, 
I SHALL be much obliged by your insertion of the in- 
closed in the Philosophical Magazine at your earliest con- 
venience. Yours very sincerely. 
To Richard Phillips^ Bsq.^ F.R.S. W. R. Grove. 
In the number of the Bihliotheque Universelle de Geneve 
for March, is published an extract from a letter of mine to 
Professor Schcenbein, giving an account of some experiments 
on the voltaic disruptive discharge'^. In the kind and flat- 
tering remarks which follow, my friend Dr. Schcenbein de- 
duces a conclusion from those experiments which I had not 
ventured to make, but as many of the readers of the Philo- 
sophical Magazine may not have seen the article in question, 
I must beg leave to give a summary of its contents. 
In considering the experiment communicated to the Phi- 
losophical Magazine for 1839, by Mr. Gassiot^ in which he 
points out the remarkable difference between the heating effects 
at the anode and cathode during the disruptive discharge,, it 
occurred to me that it might be due to the interposed me- 
dium, and that were there any analogy between the state as- 
sumed by voltaic electrodes in elastic media, and that which 
they assume in electrolytes, it would follow that the chemical 
action at the positive electrode in atmospheric air would be 
more violent than that at the negative, and that if the che- 
mical action were more violent, the heat would necessarily be 
more intense. Several experiments confirmed this view: the 
battery with which they were made consisted of 36 elements, 
each consisting of a square inch of platina foil and of zinc ; 
it was charged with concentrated nitric and dilute sul- 
phuric acid as in my first experiments (Phil. Mag., May 
1839) and arranged in single series. 
I cannot avoid here a short digression as to the oeconomy 
of this combination : this little battery required a pound of 
nitric and an equal weight of sulphuric acidf to charge it ; 
and thus for the expense of about a shilling I could experi- 
ment for 8 or 9 hours without fresh charge ; the arc of light 
* After writing that letter I had determined to delay the publication of 
the experiments, in order to add to them some others, but these have been 
unavoidably postponed. 
f The dilute sulphuric acid should be of sp. gr. T2 and four or five times 
the volume of the nitric ; where there is not this disproportion between 
the cells it will be well previously to mix the nitric with one or two mea- 
sures of dilute sulphuric acid. By proper attention to these proportions 
1 obtain by electrolysis oxyhydrogen gas at 6d. per cubic foot including 
zinc consumed, &c. 
