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ory: How does galvanism differ from common electricity ? 
This question may refer both to the nature of the phe- 
nomena themselves, and to the means employed for 
on their production. We may define galvanism, either by 
enumerating the specific isties of those events 
which we class er under this title; or, we may 
show how they have all a reference to each other, from 
the similarity of the ee that are employed for 
their developement. The definition that we have'given 
at the commencement of the article, may be regarded 
4 as sufficiently correct and comprehensive, without ex- 
__.. ceeding the limits to which a definition ought to be re- 
stricted It appears to include every action of bodies 
upon each other, which is usually considered as belong- 
ing to this particular branch of natural philosophy ; 
while it excludes those that are, by common consent, 
referred to a different de nt. It is; however, in 
some cases, difficult to draw the exact line of distinction 
between electricity and galvanism, and indeed we may 
doubt, whether any precise distinction actually exists. 
For as it is conceived, that they both depend upon the 
same agent, having merely experienced some modifica- 
tion in its nature, or mode of action, we must conclude, 
that there may be some intermediate or indeterminate 
state, which might be referred to one or the other with 
almost equal propriety. 
To recur then to the former definition: “ Galvanism 
is a series of electrical phenomena, in which the electri- 
city is developed without the aid of friction, and where 
we ive a chemical action to take place between 
some of the bodies employed.” This definition may 
perhaps be thought to limit the science too much, and 
to remove from it many facts, which have always been 
regarded as galvanic. For example, a great number of 
the original experiments of Galvani himself, and his 
immediate contemporaries, where contractions were ex- 
cited in the muscles of animals, by the application of 
the two metals, many of those of Fowler, and the first 
set of Volta’s experiments, would, according to this de- 
_. finition, be reduced to the effects of common electricity. 
__. To this objection we may reply, that wherever mois- 
_.. ture comes in contact with the zinc, or more oxidable 
» ~~ metal, it is not improbable that some chemical action is 
produced, but that it is very slight, and has therefore 
not been noticed. If, however, upon a strict examina- 
tion, it is found not to be the case, and that there is ac- 
tually no change in the chemical condition of any part 
of the apparatus, it must be admitted, that, according to 
our present ideas, the phenomena are not to be referred 
proper to galvanism. The first unequivocal experiments where 
tex- the chemical effects were observed, and were connected 
"+ with the electrical condition of the substances, are those 
of Fabroni’s; and it was not until Volta’s discovery of 
. the pile, that we were put in possession of Smethod. by 
which we were enabled to examine, with any degree of 
accuracy, the relation between these two actions, Even 
if we find it n to conclude that Galvani, al- 
though he had the good fortune to have his name asso- 
ciated with a new eae of science, did not wit- 
wness any of the facts to which we now apply the term, 
the contradiction will be more apparent than real ; and 
we must not permit the mere circumstance of names to 
influence our opinion ing the essential nature of 
things. The present state of our knowledge seems, 
however, to warrant the conjecture, that the action of 
the two metals on the parts of animals, is strictly gal- 
__-¥anic, i, e, accompanied by a chemical action on the 
metals and the fluids, so as to reduce it within the li- 
mits of the proposed definition. 
‘= GALVANISM. 
95 
Waving, however, the farther discussion of this point, 
which indeed can only be decided by experiment, we ~ 
must recur to the question already stated, respecting = — 
the essential difference between galvanism and common ¢lectricit 
electricity ; and, conceiving it to be ascertained, that and galva- 
in the production of the former, a chemical action takes nism. 
place, which 'is not necessary in the latter, we must, 
next inquire, in what way this chemical change of the What is the 
substances iniparts to the electricity that particular state chemical 
or modification which we style galvanic. . With respect “8°? 
to the nature of this chemical: change, experimentalists 
are generally agreed: as to the metals, it consists in 
the oxidation of that metal which possesses the strongest 
attraction for oxygen; and with respect to the fluid in< 
terposed between the metals, it consists in its decom= | 
position, the oxygenous part being attracted te the most 
oxidable metal, and the alkaline to that which is the 
least oxidable. Although, as we have already had oc« 
casion to remark, there are various galvanic combina 
tions, into which only one. metal enters, or even some 
entirely without metals, bcs as the most powerful and 
complete circle is that which consists of two metals with 
a fluid interposed, we shall confine our illustrations to 
this form of the apparatus. 
We may consider it as proved by a number of ex- Galvanic 
periments, which have been stated in the first of electricity 
this article, that the electricity, as it is evolved by the of low in- 
different galvanic combinations, always exists in what, "°°"? 
has been styled a state of low intensity ; and that, to 
whatever extent we increase the apparatus, and how-~ 
ever powerfully it acts, still the Tatensity is but little 
augmented. Unfortunately it is still a doubtful -point 
of theory, upon what the intensity of electricity de- 
nds, or in what it, precisely consists. Some writers pomarks oa 
ie ascribed it to a greater or less concentration of the electrical 
fluid ; some to.a difference in the velocity of its motion, intensity. 
or in the strength of its affinity for the surrounding 
bodies; and others to its containing a greater or less. 
portion of caloric. For the present, we must rest sax 
tisfied with admitting the fact of the low intensity, as 
manifested by the phenomena, without being able to 
explain its cause; and we may next proceed to inquire, 
whether there be any circumstances in the different me- 
thods of exciting or producing electricity, by the ma- 
chine or the pile respectively, which should. cause the 
first to develope the fluid in a higher, and the latter in 
a lower state of intensity, 
And here, it must be confessed, we have little to plectricity 
direct our inquiries but conjecture and uncertain ana- as excited 
logy. Of these, however, as being our only guides, by the ma- 
we must make the best use that lies in our power. It “bine. 
is generally agreed, that all bodies possess a. certain 
uantity of electricity, which is said to be natural to 
em, and which, while it remains undisturbed, mani-« 
fests no indications of its existence. There are many 
processes which alter the state of this natural electri« 
city, by which it is extricated from one body, and may 
be transferred to others in the neighbourhood. But 
this additional portion, being more than their natural 
share, seems to be retained by them with difficulty, and 
is ready to fly off in all directions, in order to restore 
the equilibrium. This may be considered as descrip- 
tive of what occurs in the operation of the common elec- 
trical machine, where, by the friction of the rubber 
against the cylinder, a portion of the electric fluid is 
carried off from one or both of them, and is transfer- 
red to the conductor.. From the conductor it may be 
communicated to a variety of other bodies that are 
placed within the sphere of its influence ; but, in all 
