Mr. Grove on the Subject of Mr. Daniell’s ast Communication.33 
the change by following up the| remained steady for six 
principle of diminishing con- | hours.” 
trary electromotive powers 
and resistances to a current 
originating with the zinc.” 
The “ very obviously ” requires nocomment; Mr. Daniell 
will, I have no doubt, have the goodness to point out to me 
where he has published anything about the principle of con- 
trary electromotive powers and resistance previously to the 
publication of my battery; I cannot find it, and yet I suppose 
this is the principle which he deduced and I further applied. 
Although I have stated the actual deduction which led to my 
battery, I have no rigbt to disclaim any assistance which I 
might have received from experiments published previously to 
mine; I object to no one for referring my experiments to any 
previous ones; I only protest, and intended my last letter on 
this subject as a temperate protest, against being represented 
as myself assenting to certain undefined principles. One more 
parallel passage. 
Professor Daniell, Phil. Mag., 
Dec. 1842, p. 421. 
“What this [the gold leaf 
experiment] has to do with the 
nitric acid battery, in which 
the two acids in contact are 
the nitric and sulphuric, I 
really cannot perceive. The 
origin of the force in this case 
has always appeared to me to 
be the action of the zinc upon 
the dilute sulphuric acid, but 
Professor Grove may possibly 
consider it to be still the con- 
tact of the two acids. He has, 
however, stated that he was 
so led to the construction of 
his battery, &c.” 
Mr. Grove, Phil. Mag., May 
1839, p. 388, referred to in 
my letter of November last. 
‘It now occurred to me, 
that as gold, platina, and two 
acids [the nitric and hydro- 
chloric| gave so powerful an 
electric current, @ fortiorz, the 
same arrangement, with the 
substitution of zine for gold, 
must form a combination more 
energetic than any yet known.” 
[And so it did.} 
I find nothing here about the origin of the force in this case 
being the contact of the two acids; Professor Daniell will, 
perhaps, be good enough also to direct my attention to where 
ave so expressed myself. 
I find, moreover, that three elements out of four differed 
from those of Mr. Daniell, and that the fourth, viz. zinc, is 
that which has been used for voltaic batteries since the time 
of Volta. I subsequently recommended sulphuric acid as a 
cheap substitute for hydrochloric: I will not enter into detail 
Phil. Mag. S. 3. Vol. 22, No, 142. Jan. 1843, D 
