488 M. PoggendorfF on Galvanic Circuits composed of 
regard need be had to an isolated fact speaking apparently in 
favour of the chemical theory^ considering the numerous objec- 
tions which may be urged against it. 
In general they may have contented themselves with this 
otherwise perfectly correct position^ that one metal, as soon as 
it is in contact with two fluids, can no longer be regarded as a 
single metal ; so, for instance, that in Faraday^s experiment 
that end of the zinc-bar which touched the sulphuric acid 
would be positive towards that which was moistened by the 
solution of the iodide of potassium. This at least is the opi- 
nion which Pfaff advances in his Revision der Lehre vom 
Galvano-Voltaismus^, Pfaff is also, as far as I am aware, the 
only philosopher on the continent who has hitherto publicly 
discussed this experiment, without, however, performing more 
than a mere repetition of it experimentally. 
From the great importance which, be it with justice or not, 
is assigned by the majority of the philosophers of the present 
day to the decision of the question respecting the origin of 
voltaic electricity, a more accurate examination of the process 
in the Faradayan circuit appeared to me not to be without 
value, and I therefore undertook the experiments, the results of 
which will be enumerated in the following pages as briefly and 
clearly as possible. 
Galvanic circuits of two fluids and two metals not in contact 
may truly, as is readily conceived, be constructed without num- 
ber. The English philosopher has examined a few, and these 
few always composed only of zinc and platina with various 
fluids. With this slight number of cases he always obtained 
results favourable to his view. 
It appeared in the first instance to me to depend on this 
point : let it be seen whether among the great number of possi- 
ble cases there may not be some which could not be brought 
under this view. If this question were affirmed by experiment, 
another demand would arise ; namely, to subject Faraday’s ex- 
planation even for the apparently favourable cases to a more 
rigorous examination. 
Above all, I considered a greater change with the metals to 
be necessary, as, from long-known experience in other cases, it 
seemed to me highly improbable that the negative metal of the 
* P. 81. It stands there, it is true, quite reversed, that the platina was 
positive in the acid, and the zinc negative; hut the connexion shows that this 
is only founded in a permutation or typographical error. In this memoir that 
metal is always termed positive which acts towards a second as zinc to copper 
in the common circuit. 
