ELEC T 
if, being well exhaufted, one end of it be connected with 
a large conductor.—The preceding experiments mutt be 
performed in a dark room. 
From tlie refemblance between thefe electrical ap¬ 
pearances, and tire atmofpherical phenocnena of the au~ 
rora borealis, meteors, Sec. it is inferred, that thefe phe¬ 
nomena are produced by the eleCtric fluid. The luccefs 
of the foregoing experiments depends, it is highly pro¬ 
bable, upon the air in the jar, tube, &c. being rarefied 
in a high degree; for Mr. W. Morgan, who was deeply 
fkilled in calculations and political arithmetic, has (hewn, 
that a pcrfeEl vacuum is abfolutely impermeable to the 
eleCtric fluid. See Phil. Tranf. vol. lxxv. 
XXVI. Some fifties have the property of giving fhocks 
analogous' to thofe of artificial electricity ; namely, the 
torpedo, the' gymnotvs cleElricus, the filurus eleElricus , and 
the tetrodon cleElricus .,—If the torpedo,- whilft (landing in 
water, or out of water, but not inhibited, be touched 
with one hand, it generally communicates a tremulous 
motion or flight fliock to the hand. If the torpedo be 
touched with both hands, at the fame time, one hand 
being applied to its under , and the other to its upper, fur- 
face, a (hock will be received exaCtly like that oc.cafioned 
by the Leyden phial. When the hands touch the fifh on 
the oppofite furfaces, and juft over the eleCtric organs, 
then the fliock is the (trongeft; but no fliock is felt, if 
both hands are pladed upon the eleCtric organs of the 
fame furface ; which (hews that the upper and lower fur- 
faces of the eleCtric organs are in oppofite Hates of elec¬ 
tricity, atifvvering to the plus and minus fides of a Leyden 
phial, or coated plate.—The fliock given by the torpedo 
when in air, is about four times as ftrong as when in wa¬ 
ter ; and when the animal is touched on both furfaces by 
the fame hand, the thumb being applied to one furface, 
and the middle finger to the oppofite, the (hock is felt 
much (tronger than when the circuit is formed by both 
hands. This power of the torpedo is conducted by the 
fame fubftances which conduCt electricity, and is inter¬ 
rupted by thofe fubftances which are non-conduCtors of 
electricity. A circuit may be made of feveral perfons 
joining hands, and the fliock will be felt by them all at 
the fame time; but the fliock will not pafs through the 
leaft interruption of continuity, not even the diftance of 
the two hundredth part of an inch.. No elective attrac¬ 
tion or repulfion could be ever obferved to be produced 
by the torpedo, nor, indeed, by any of the eleCtric fillies. 
The (bocks of the torpedo feem to depend on the will of 
the animal. 
The gymnotus eleCtricus, or eleCtrical eel, poflefles all 
the electric properties of the torpedo, but in a fuperior 
degree, When final 1 fifh are put into the water wherein 
the gymnotus is kept, they are generally ftunned o.r killed 
by the (hock; and then they are fwallowed, if the ani¬ 
mal be hungry. The ftrongeft fhock of the gymnotus 
will pafs > a very fliort interruption of continuity in the 
circuit. When the interruption isfoymed by the incifion 
made by a pen-knife on a flip of tin-foil that is pafted on 
glafs, and that flip is put into the circuit, the fliock, in 
palling through that interruption, will (iiew a fuull but 
vivid (park, plainly to be feen in a dark room. The 
gymnotus feems alfo to be polfeffed of a fort of new fenfe, 
by which he knows whether the bodies prefented to him 
.are conductors or not. Thi$ faCt was afoertaiued by a 
great number of experiments made by Mr. WaTfli. 
The (ilurus eleCtricus is known to have the power of 
giving a ftrong fliock ; but not fo powerful as that of the 
gymnotus. The fourth eleCtrical fifli waS'found on the 
coaft of Johanna, one of the Comoro iflands, in latitude 
12° 13' fouth, by lieut. William Paterfon, in 1786. It 
is the Tetrodon eleCtricus of the Linmean fyftem ; and an 
account of it was fir ft publifhed in the 76111 vol. of the 
Pllil. Tranf. For the very curious and interefting natu¬ 
ral hiftory of thefe eleCtrical fillies, and figures of them, 
fee the articles Gymnotus, Raja, Silurus, and Te¬ 
trodon. 
Vol. VI. No. 362, 
UCITY. 433 
When electricity is flrongly communicated to infulated 
animal bodies, the pulfe is quickened, and perfpiration 
increafed ; and, if they receive or part with their electri¬ 
city cn a fudden, a painful fenfation is felt at the place of 
communication. But what is more extraordinary is, that 
the influence of the brain and nerves upon the mufcles 
feems to be of ,an cleElivc nature. We are indebted for 
this difeovery to M. Galvani, a learned Italian, who 
denominated that part of the fcicnce, animal electri¬ 
city ; and,which, from his name, fubfequent writers 
have chofen to denominate Galvanism. We (ball give 
the principal of his observations, together with fome il- 
luflrative experiments. 
1. Tl;e nerve of. the limb of an animal being laid bare, 
and ftirrounded with a piece of tin-foil, if a communica¬ 
tion be formed between the nerve thus armed, and any of 
the neighbouring mufcles, by means of a piece of zinc, 
flrong contractions will be produced in the limb. 2. It 
a portion of the nerve which has been laid bare be armed 
as above, contractions will be produced as powerfully,by 
forming the communication between the armed and bare 
part of the nerve, as between the armed part and mufcle. 
3. A fimilar effett is produced by arming, a nerve, and 
limply touching the armed part of the nerve with the 
metallic conductor. 4. Contractions will take place if a 
mufcle be armed, and a communication be formed by 
means of the .conductor between it and a neighbouring 
nerve. The fame effeCt will be produced it tlie commu¬ 
nication be formed between the armed mufcle and ano¬ 
ther mufcle which is contiguous toit. 5. Contractions 
may be produced in the limb of an animal, by bringing 
•the pieces of metal into contaCt with each other at fome 
diflance from the limb, provided the latter make part ot a 
line of communication between the two metallic con¬ 
ductors. 6. Contractions can be produced in the ampu¬ 
tated leg of a frog, by putting it into water, and bringing 
the two metals into contact with each other at a (mail 
diftance from the limb. 7. The influence which has 
pafted through, and excited contractions in, one limb, 
may. be made to pafs through, and excite contractions in, 
another limb. S. The heart is the only involuntary 
mufcle in which contractions can be excited by thefe ex¬ 
periments. 9. Contractions are produced more (tr.ongly 
the farther the coating is placed from the origin ot the 
nerve. 10. Animals which were ajmoft dead have been 
found to be confiderably revived by. exciting this in¬ 
fluence. 11.. When thefe experiments are repeated upon 
an animal that has been killed by opium, or by the elec¬ 
tric fliock, very flight contractions are produced ; and no 
contractions whatever will- take place in an animal that 
has been killed by corrofive fublimate, or that has been 
ftarved to death. 1.2. Zinc appears to be the bed exciter 
when applied to gold, fllver, molybdena, fteel, or copper. 
The latter metals, however, excite but feeble contrac¬ 
tions. when applied to each other. Next to zinc, in con¬ 
tact with thefe metals, tin and lead, and (liver and lead, 
appear to be the molt- powerful exciters. Thefe facts 
are exemplified b\ the following experiments : 
Place the limb of an animal, a frog, for inftance, upon 
a table ; hold with one hand the principal nerv.e pre-vi- 
oufly laid bare, and in the other hold a piece of zinc; 
let a (mall plate of lead or filv.ei; be then laid upon the 
table, at fome diftance from the limb, and a communica¬ 
tion be formed, by means of water, between the lim,b and 
the part of the table where the m tal is lying. If now, 
the fllver be touched with the zinc, contractions will be 
produced in the limb the moment that the metals come 
into contaCt with each other. The. fame effect will be 
produced, if the two pieces of metal be previoufly, placed 
in contaCt, and the operator touch one of them with his 
finger. 
Let two amputated limbs of a frog be taken ; let one 
of them be laid upon a table, and its toot be folded in a 
piece of fllver ; let a perfon lift up the nerve ot this limb 
with a fllver probe, and another perfon.hold in his hand a 
3 S piece 
