546 M. Poggendorff on Galvanic Circuits composed of 
phuric acid^ without this addition of nitric acid^ afford in most 
cases the opposite result? Want of chemical action on the 
zinc it certainly is not ! And then, how, even according to the 
affinity-theory, is the action of the nitric acid to be explained ? 
A long discussion might here be opened; I will, however, 
merely touch upon one point. Faraday states that the addition 
of nitric acid to the sulphuric acid increases the intensity of the 
chemical action ; and, after communicating some facts from 
which he draws the conclusion that this acid does not increase 
the quantity of the electricity, he adds : This mode of increa- 
sing the intensity of the electric current, as it excludes the effect 
dependent upon many pairs of plates, or even the effect of 
making any one acid stronger or weaker, is at once referable to 
the conditions and force of the chemical affinities which are 
brought into action, and may, both in principle and practice, 
be considered as perfectly distinct from any other mode*.” 
Here we may with justice put the question. What measure 
then do we possess for the intensity of a chemical action? 
When the question is, as to the attack of an acid on a metal, 
we have, I believe, no other measure than the quantity of the 
metal which is dissolved from the unity of surface in the unity 
of time. But with this, certainly the most natural, view, there 
exists no reason why the nitric acid should enjoy any single 
advantage over the sulphuric acid, when these acids are taken of 
such a degree of concentration that they both dissolve just the 
same quantity of a like zinc surface in the same time. An ad- 
vantage, according to Faraday^s theory, is the less to be expected, 
as both acids are non-electrolytes, and their effect therefore 
could only be of like nature, and merely consist in increasing 
the affinity of the oxygen of the water for the zincf. But 
* Faraday’sExperimentalResearches, § 908. It maybe observed that 
what the P'aradayan theory terms the increase of the quantity of the electricity 
is the same as heightening the force of the current by diminishing the resist- 
ance ; for instance, enlarging the surfaces, increasing the concentration of the 
fluids, therefore precisely the same as diminishing the denominator of Ohm’s 
formula. By electrolytic intensity, or intensity of the electricity, this theory on 
the other hand understands, at least with the simple circuit, the electromo- 
tive force, or the numerator of this formula. But both expressions are some- 
times used in a different sense, of which I have already given an example in 
the Annalen, vol. xlvii. p. 128 and of which the explanation of the differ- 
ence between the current of the pile, and that of the simple circuit (Exp. 
Res. § 994), — an explanation so perfectly simple, according to Ohm’s theory, 
— gives a further proof. 
f However, with the nitric acid, whether employed alone, or mixed with 
sulphuric acid, the process is not so simple, even with the above-mentioned 
A Translation of the Memoir of Ohm has just appeared in Part VII. of 
the Scientific Memoirs. — Edit.] 
