7797+] 
by raifing or depreffing the. irritable. 
Capacity of the animal organs, in a variety 
of ways. : 
What is the fenf ation which 1s pro- 
duced by Galvanic irritation? is a 
queftion, the ese of which M. 
Humboldt propofes to undertake, No 
one, he obferves. can {peak to this point 
with more precifion than himfelf,; hav- 
ing made a number of diferent experi- 
racats».on his perton, fome of which 
related to the focket ef a tooth which he 
had extraéted; fome to the wounds 
which he had caufedsto be made in his 
hand, &c.; and {ome to the eZeéts pro- 
duced by the four veficatory plafters. 
The following are his own obferva- 
tions on the fubject : : 
- Phe Galvanic irritation ts always. at- 
tended with pain, ‘and the more fo, 
the part irritated is the more hurt, an i‘ 
asthe irritation lafts a longer {pace of 
‘time. Che-firft impreifions are perceiv- 
ed but flrghtly.; afte peas follow five or 
fix much more acute; and which, at 
length, become aces fupportable, till 
the. whole irritated nerve is ‘rendered 
torpid) with imceflant irritation. The 
fenfation excited, bears. no refemblance 
to that which is generated by fhocks, 
or the eleétric bath; it js a pain of its 
own kind, neither pungent, nor ‘pinch- 
ing,*mor penetrating, nor. vet cealing, 
after the manner. of hoe! wiih, jee 
cited by the electric fluid. A violent 
ftroke- or pang may .be difinguithed ; 
alfo a regular preffure, accompanied by 
an ardent heat; and that heat incoin. 
p2rably more fierce when the wound is 
covered, with a-plate of) filver, and irri- 
tated -by a flick of ‘zinc, than when the 
zine plate is laid on the wound, and the 
filver tweezers are made ufe ee in order 
to eftablifh the communication. 
This communication, when ee in 
contact with the epidermis, produces no 
refult whatever; it appears, that the 
flefhy tkin~.infulares. like. the  giafs 
which may be laid between the wound 
_and the metals ::bur, if che fim’ be 
laid naked by two wounds at eight 
inches. diftance, and if. on one wound 
a-plate of zine be applied, and on the 
other a prepared frog’s leg, 
begin to contraét as fon! ie it commu- 
nicates with the zinc by the filver wire ; 
an evident indication that the Galvanic 
fluid is then pafling under-the epidermis. 
This fluid produers; 4 in fome inftances, 
avery perceptible acid favour or tafte ; 
the two wounds of M. Humboldt hav- 
ing been covered, the one with filver, 
MonTHLy Mac. No. XVII. 
Humboldi’s Experiments on. Galvan iff. 
~ ly, 
this laf will. 
349 
and the o her with zinc, an iron wire, 
many feét in length, attached to re 
Zloc, was applied between lis upper lip. 
and the fpongy fubitance of his teeth, and 
from thence upon the tongue of another 
perton; when the iron Wire was made to 
come nigh the filver, there was \a Hong 
‘contraction of the feapular mufele: and 
at.the fame inftant, the perfon whofe 
tongue was in the (chain, perceived a 
fentation of acidity. Lhere are even 
cafes in which the fluid aéts on the organ 
or taftc, without producing any fenfibdle 
effect on the organs of motion ; a in- 
ftance of this occurs, when the epidermis 
ferves asia conduc for of the zinc to the 
frog; there is then no contraction cb- 
ferved, but-an acid favour remains upon 
the tongue. 
Having ‘learned from M. Voura, 
that -pearl-athes liqaified (oleum taxtari 
Ka deliqiuum) might be ufed to augmant 
€ power of the conductor, If, ages 
BOLDT availed himfel? fuccefstully of 
this procefs to ext tend the capacity of the 
animal organs. Having moittened one 
of ‘his wounds with the faid liquer, he 
did not feel any great pain from it, al- 
though the Galvanic irritation was more 
violen it, and attended with more hear; 
fparks, however, appeared and veriine 
before his eves; his tongue, m-itencd 
with the ed diftinétly bercetved the. 
acid fenlation, althcugh “the chain was 
only eftablifhed between the zinc and the 
zinc; while the frog’s leg, moiftened 
with the alcaline diffolution, and laid on 
a plate of glafs, without touching: either 
metal or carbonic matter, fell ae itfele 
violent convulfions, the- twin 
nufcles and the legs. quivering in- 
cofanelys 5 by this meaus, irritabilit cy was 
re-eftablifved in the animal’parts, where 
lt had gon ae a by hot folu- 
tious of oxide of arfenic; and; final- 
¥y.the irritation (which only takes 
place, for the moft part, when the nerve 
and the imufcle are. armed with the 
fame metal, the different metals being 
between the two) becomes evident after 
this preparation—a circumitance which 
feems to indicate, that the alkali nor 
only irritates the nerve, but thatit adds 
to its irritability. 
The autaor afterwards applied this 
procefs toa number of amphibious ani- 
mals, which he thereby drew out of their. 
winter’s fleep, and in all of which he 
diftiaguifhed peculiar fymptoms of irri- 
tability. 
Thefe obfervations led him to diftin- 
guifh a two-fold ftate ef the animal 
Lz organ ; 
wt» 
1Ato 
