History. 
Valli’s let- 
ters, 1792. 
Fowler’s 
Essay on 
Animal E- 
lectricity, 
179s. 
Are galva- 
nism and 
electricity 
the same ? 
Effect on 
the volun- 
tary and in- 
voluntary 
anuscles, 
80 GALVANISM. 
Galvani had no sooner published an account of his 
discovery, than the philosophers, in different parts of 
Europe, entered with eagerness upon the examination 
of the new phenomena. The earliest writers on the 
subject were Valli, Fowler, and Volta. The principal 
object’of Valli’s letters, which appeared, in the Journal 
de Physique, was to examime how far the opinion.of 
Galvani was correct; respecting the dependence of the 
new influence upon the nervous fluid, and its identity 
with electricity. Although much of his reasoning must 
now be regarded as erroneous, yet still he displays con- 
siderable ingenuity and address in the contrivance.of 
his experiments, and in the inferences which he dedu- 
ced from them. 
In the following year; Dr Fowler published an Essay 
on Animal Electricity, in» which he displays, an. acute 
and. sagacious iind. and. may be considered, by his 
observations, to-have paved the way for many of the 
discoveries of his successors. At the time when he 
wrote, the question was warmly agitated, whether the 
phenomena of galvanism could be referred to the elec- 
tric fluid, or whether they do not depend upon some 
specific agent peculiar to the animal body.. He com- 
mences by the inquiry, ‘‘ Are the phenomena exhibited 
by the application of certain different metals to animals 
referable to electricity?’ Although he conducts. his 
train of reasoning with much. ability, yet he drew the 
conclusion which we are now enabled to say is not cor- 
rect. After examining minutely the circumstances 
which are necessary for the production. of the galvanic 
influence, he finds that it is requisite that there should 
be two different metals, which are to communicate with 
each other and with the, animal. He eonceives it ne- 
cessary that they should ‘be in contact, one with the 
nerves, and the other with the muscles, and. points out 
an error, into which Valli had fallen in his experiments, 
where he thought that the contact of the nerve only is 
sufficient to cause the contractions: he shews that, in 
this case, the moisture on the surface of the nerve acted 
as a conductor of the influence of one of the metals to 
the fibres of the muscle. 
Dr Fowler concludes that the galvanic influence is 
not referrible to electricity, because for the production 
of the former, the presence of two different metals ap- 
's to be necessary, while electricity, as proceeding 
from the electrical machine, is excited by the action of 
an electric upon a conductor; an inference which was 
correct, according to the state of the science at the time 
when he wrote. He also endeavours to show that elec- 
tricity and galvanism are not, in all cases, conducted by 
the same substances, and particularly adduces charcoal, 
which, although a conductor of electricity, is impervious 
to the galvanic influence. He afterwards made some 
curious observations upon the effect of galvanism. on 
animals not furnished with distinct limbs, suchas worms 
of various kinds. \ These animals could not be made to 
contract, yet by the nature of their motions. they seem- 
ed to be sensible to the impression of the two. metals, 
when they were placed, partly on one, and partly on 
the other. 
Dr Fowler afterwards enters upon an interesting in- 
quiry respecting the effect of galvanism on. the. diffe- 
rent parts of the body. ‘* What are the relations which 
subsist between the influence discovered by Galvani, 
and the muscles, the nervous, and the vascular systems 
of animals?” He found that the contractions were very 
readily excited in. all the muscles which are subservient 
to the will, but that they wete with great difficulty 
produced in the heart, and that they could not be ren- 
dered perceptible in the stomach and intestines. He 
observed that when a part is in a state of inflammation 
it acquires an additional sensibility to the galvanic sti- 
mulus, and he made the curious discovery of the flash 
of light, which is produced by placing the two metals 
in contact with the ball of the eye, and then causing 
them to communicate with each other; Sultzer, a Ger-: 
man metaphysical writer, had mentioned several 
before, the manchayensinney! on the organ of taste, by 
applying, two metals, one above and the other below 
e tongue, and then bringing them into contact; but 
the sensation was ascribed to a peculiar vibration ex-. 
tongue, were varied in, different wa‘ 
bison, an account of which is. published at the end of 
Dr Fowler’s Essay. Professor Robison mentions the 
sensation of taste which is excited, when the tongue is 
applied to the edges of a number of plates of zinc and, 
silver, yee alternately upon each other ; a construc- 
tion which may be regarded as an approximation to the 
apparatus afterwards Rassias! by Volta. 
In thesame year in which Fowler’s Essay was publish- 
ed, a very important communication appeared in the Phi- 
losophical Transactions of London, from the pen of Volta, 
in the form of letters to Cavallo. 
account of Galvani’s discovery, and adds many curious 
experiments and valuable remarks of his own. He at~ 
tempted, and with complete success, to overthrow Gal. 
vani’s opinion, that the animal body bears an analogy 
to the Leyden phial, the nerve and the muscle being 
in opposite states of electricity. He found that for the 
P uction.of the effect it was essential to have two dif- 
erent metals, and hence he/arrived at the important 
conclusion, which may be regarded as leading to.all his 
future discoveries, that the muscular contractions are 
produced by small. portions of electricity, that are li- 
berated by the action of the metals upon each other. 
Another point which Volta established was, that the 
nerve is the organ on which the’ galvanic influence im~ 
mediately acts; but he found that if a part of a muscle 
be laid upon two different metals, and these be made 
to communicate, a contraction is produced. This pro- 
bably depends upon the nervous matter that is disper- 
sed through the muscles, and also upon the moisture 
that is always present, and which serves to conduct the 
electricity to all parts of the body. Volta performed 
many experiments in order to discover, what circum- 
stances are favourable to the excitation of the contrac- 
tions, and upon the parts of the body which are the most 
easily called into action. His observations agree, in 
many respects, with Fowler’s, although it is certain 
that their experiments must have been made without 
concert or communication. He found that snails and 
worms could not be made to eontract, but that many 
of the insects, as butterflies and) beetles, were subject to 
the influence of the metals... It appeared from his nu- 
merous trials, that those animals alone were sensible to 
galvanism, who are furnished with distinct limbs, ha- 
ving flexor and extensor muscles. In the animals of 
this description, it appeared that. it was the voluntary 
muscles alone which are capable of being made to con- 
tract. Although the heart is a muscle which is easily 
thrown into powerful action; by chemical or mechanical 
stimuli, yet he could never produce-any effect upon it 
by the action of the two metals. Volta made some of 
the same observations upon the effect of the two metals 
on the organs of sense, as have been mentioned in our 
abstract of Fowler’s Essay. 
He gives a luminous . 
Effec 
the eye 
tongue 
Volta’ 
ters, 1 
