404 
ELECTRIC I T Y. 
piece of zinc, with which he is to touch the filver in¬ 
cluding the foot; let tlie perfon holding the zinc in one 
hand, catch.with the other the nerve of the fecond limb, 
■atid, he -.who touches the nerve of thefirft limb, is to hold 
in the other hand the foot of the fecond ; let the zinc 
tuny be applied to the (river, including the foot of the 
find, and contractions will be immediately excited in 
both limbs. 
Take a living flounder, lay it flat in a pewter plate, or 
upon a (beet of tin-foil, and put a piece of-filver, as a 
fit ill big,."'or a half-crown, upon the frill. Then, by means 
of a piece of metal, complete the communication between 
the pewter plate, or tin-foil, and the filver piece, on 
doing which the animal will give evident tokens of being 
a defied. 
Let a perfon lay a piece of zinc upon bis tongue, and a 
half-crown, or other filver, by the fide'of it; on forming 
a communication between thofe two metals, by bringing 
their two edges into contadl, h'e will perceive a peculiar 
fenfation, a kind of cool fub-acid taffe, not exactly like, 
and yet not much different from, that produced by artifi¬ 
cial electricity. 
In a medical view, electricity has been adminiflered for 
various difeafes. Cavallo has taken great pains in afeer- 
taining the cafes in which electricity has been fuccelf- 
f"i1 11 y applied. We are informed by that gentleman, that 
rheumatic dij'orders, even of long Handing, are relieved, and 
generally quite cured. Deafnefs, tlte tooth-ach, fwellings 
in general, inflammations of every fort, palfies, ulcers, 
cutaneous eruptions, the St. Vitus 5 dance, fcroplnilous 
tumours, cancers, abfeefres, nervous head-achs, the drop- 
fy, gout, agues, and obftructions, have been all confide- 
rably relieved, and in many inftances perfectly cured, by 
the application of the eleCtrical fliock, which is to be 
thrown on the difeafed part. This remedy, however, 
fliould be reforted to with great caution ; and never ap¬ 
plied but under the direction of a regular-bred phyfician. 
Animal eleCtricity naturally fuggefted animalmagnetifm. 
The firft notice of the aCtion of eleCtric influence upon 
the nervous fyftem, was brought forward at Paris, by 
Mefner and his pupil Deflon. The furprife and afionifti- 
ment withwhich, from its novelty, it was accompanied, 
evidently influenced the powers of the mind. It feemed 
to affeCt the whole animal economy, and, for a time, ex¬ 
cited the mod extraordinary emotions. Thefe paflions 
evidently relulted more from the influence of the imagi¬ 
nation, than from any of the pretended powers of animal 
electricity. Hence quacks and empirics took advantage 
of the public credulity, and covering their impofitions 
under the fafeinatihg veil of mydery, pretended that its 
occult virtue could change ayerfion into love, and love 
into avorfion ; that it could create pain, heal wounds, and 
cure difeafes, as if by enchantment. The whole of,this 
mydery, however, and its-confequent fraud, is now un¬ 
veiled by the experiments of Galvani and his followers, 
-who have clearly defined the operation of electricity upon 
the animal fyftem, and thus introduced a valuable acqui- 
fition to medical practice. 
XXVII. There is a confiderable analogy., and difference, 
between magnetifm and electricity.—The power of elec¬ 
tricity is of two forts, pofitive and-negative ; bodies pof- 
fefled of the fame fort of electricity, repel each other, 
and thofe pofTeffed of different forts attraCt each other. 
In magnetifm, every magnet has two poles ; poles of the 
fame name repel each other, and the contrary poles at¬ 
tract each other.—If a thin glafs plate coated with red 
fealing-wax, be fet on pofitive and negative globes, and 
we fprinkle (from a confiderable height) a fine powder of 
black fealing-vvax, and then agitate the plate gently with 
a glafs rod, the particles of wax powder will gradually 
arrange themfelves into curve lines, diverging from the 
point over one of the globes, and converging to the point 
over the other, precifely like the curves formed by iron- 
filings fprinkled on a paper held over a magnet. Each 
little rag of wax becomes eleCtrical by pofition, acquires 
two poles, and the pofitive pole of one attracts the nega¬ 
tive pole of another ; and they adhere in a certain deter¬ 
minate pofition, nearly a tangent to the curve, and indi¬ 
cates the law of magnetic action. When in this date, if 
a hot brick be held over the plate till the wax foften.a 
little, the particles of black wax will adhere to the red 
coating, and give a permanent fpecimen of the adfion. 
In electricity, when a body in its natural date is brought 
near to one electrified, it acquires a contrary electricity, 
and becomes attracted by it. In magnetifm, when a fer¬ 
ruginous fubdance is brought near to one pole of a-mag¬ 
net, it acquires a contrary polarity, and becomes attrac¬ 
ted by it. 
One fort of electricity cannot be produced by itfelf. 
In like manner, no body can have only one magnetic 
pole. The eleCtric virtue may be retained by eleCtrics, 
but it eafily pervades non-eleCtrics. The magnetic vir¬ 
tue is retained by ferruginous bodies, but it eafily per¬ 
vades other bodies. On the contrary, the magnetic power 
differs from the eleCtric, in that it does not afteCt the 
fenfes with light, fmell, tade, or noife, as the eleCtric 
does. Magnets attract only iron, whereas the eleCtric 
power attracts bodies of every fort.—The eleCtric virtue 
refides on the fur-face of electrified bodies, but the mag¬ 
netic is internal.—A magnet lofes nothing of its power 
by magnefying other bodies, but an electrified body lofes 
part of its electricity by electrifying other bodies. See 
the article Magnetism. 
LAWS of ANIMAL ELECTRICITY, or 
GALVANISM. 
The difeovery of the eleCtric influence on the animal 
fibre, and the cenfequent experiments publiflied by Gal¬ 
vani, foon drew the attention of philofophers in all parts, 
to the invelligation of fo curious and intereding a pheno¬ 
menon. It was long contended that this fecret operation 
of nature arofe from a principle altogether different and 
didinCt from that of electricity ; and, inafmuch as tills 
principle appeared to be brought into aCtion by the 
agency of metals, it was believed that till the phenomena, 
refulted from a particular fluid inherent in metallic bodies, 
wliich could only be communicated to animal fubftances 
by the force of touch. In the year 1800, however, thefe 
fallacious hypothefes were removed, by means of the in¬ 
genious apparatus, or pile, of M. Volta, profeffor of phi- 
lofophy in the univerfity of Pavia, with which he was 
enabled clearly to demondrate, that the galvanic influ¬ 
ence was neither more nor lefs than an excitation of the 
common eleCtric fluid. 
This apparatus conlids of a number of copper or filver 
pieces or plates, with an equal number of plates com- 
pofed of zinc, and a fintilar number of pieces of card, 
leather, pafteboard, or woollen cloth, which diould be 
foaked in water f.iturated with common fait, muriat of 
ammonia, or nitre. The filver or copper may be pieces 
of money, and the plates of zinc may be cad of the fame 
(ize. A pile is then formed, by placing a piece of filver 
on a correfponding one of zinc, and on them a piece of 
wet cloth, or card: which is to be repeated alternately, 
till the number required be piled up in regular fuccef- 
fion. But, as the pieces are apt to tumble down, unleis 
properly fecured, it will be-advifable to fupport them 
by means of three rods of glafs, or baked wood, fixed 
into a flat wooden pededal, and touching the pieces of 
metal at three equididant points. Upon thefe may he 
made to Aide a fmall circular piece of wood, perforated 
with three holes, to receive the glafs rods at top, which 
will ferve to keep the pile firm, and the different layers 
in clofe contaCt. The moiftened pieces of cloth fliould 
be fomewhat fmaller than thofe of the metal, and gently 
fqueezed before they are applied, to prevent the luper- 
fluous moiffure from infuiuatlng itfelf between the pieces 
of metal. Thus conftruCied the apparatus is called the 
Voltaic pile , and will afford a,perpetual current of the ani- 
mal-eleftric fluid, through a»y conductor that comrounu 
cates 
