415 
ELECTRICITY. 
the means of very fmall gold wires, fucceeds in decom- 
pofing water by the eledtrical machine, nearly in the 
fame manner as is effedted by galvanifm. Van Marum’s 
method is by an interrupted explofion ; while, in the cafe 
of Dr. Wollafton’s, the production is tranquil and pro- 
greflive/ 
The decompofition of water by the galvanic pile, is of 
great life in the elucidation of its decompofition by elec¬ 
tricity, which has excited fo much the attention of phi- 
lofophers. Tt has appeared difficult to comprehend how 
an electrical explofion (hould effeCt a decompofition of 
water; and, when it has been decompofed, (hould ccca- 
fion its re-compofition. By the galvanic operation, we 
find this to be occafioned by the palfage of a conllant 
current of a fmall intenfity of electricity, palling through 
an imperfeCtly conducting medium. The refiftance it 
meets with occafions the reparation of the conftituent 
parts of the water, the aCtual fubftance of which is per¬ 
vaded by this fubtile principle, which thus breaks the 
bond of union of its conftituent parts. When thefe gafes 
‘are inflamed by the eleCtric fpark, it is not the eleCtri- 
cky which. direCtly. occafions the explofion ; it being pro¬ 
duced by the caloric elicited from other fubftances, by 
the interrupted palfage of the eleCtric fluid. 
It is a curious and remarkable faCt, that inflammable 
fluids, fuch as oil, alcohol, &c. cannot be decompofed 
by the galvanic procefs, unlefs by the medium of the 
palfage of a fpark. Thus, in the preceding engraving, 
at fig. 32, let us fuppofe C D to reprefent a glafs vefifel 
half filled with alcohol; let A B be two pieces of well- 
prepared charcoal, one of them connected, by means of 
a wire, with the zinc end of a powerful battery, and the 
other piece joined in the fame way to the copper extre¬ 
mity. As often as the ends E F, which are immerfed in 
the alcohol, are brought into contaCt, a brilliant fpark is 
produced, and bubbles of air are given out. Upon con¬ 
tinuing the procefs, provided the battery be very power¬ 
ful, the fpirits will almoft boil. The air, which is ra. 
pidly difengaged, when collected in a receiver, proves to 
conlift of carbonic acid gas, and hydro-carbonat gas. As 
alcohol is compofed of oxygen, hydrogen, and carbon, at 
the inltant of decompofition new combinations take place. 
The nafcent hydrogen, uniting with the carbon, confti- 
tutes the hydro-carbonat; and the remaining portion of 
carbon, blended with the oxygen, forms the carbonic 
acid. Th.e fame refults follow the decompofition of oil. 
The decompofition of water by galvanifm is governed 
by the laws which apply to animal fubftances. The ra¬ 
pidity of the decompofition is in proportion to the num¬ 
ber of the plates, and not to the furface; till we reach 
the limits particularized,,in fpeaking of the influence of 
fmall plates. In the battery of (ix hundred fmall plates 
before defcribed, the decompofition is by no means equal 
to a battery of fixty plates each of which has a furface 
of four inches. 
We are fold that it was with the celebrated electrical 
apparatus at Haerlem, madeby Mr. Cuthbertfon, that the 
beautiful metallic oxyds were firft (truck upon paper, 
each of the metals having produced its peculiar charac- 
teriftic tint. The mode of performing thele curious ex¬ 
periments is reprefented in the Electricity Plate III. 
fig- 33- AB is a plate eleCtrical machine, on tire fame 
principle with that In the Teylerian mufeum at Haer¬ 
lem ; CD a battery ex poling a coated furface of about 
eighteen feet; and GH a fine metallic wire,Tecured by 
pins in fuch a way as to be railed from the paper about 
cne-eighth of an inch. The frame of wires is connected 
with the battery by means of the chain F. Upon dis¬ 
charging the battery by the rod E, the wire explodes, 
and isdiflipated in the air. Having been difperfed in 
every direction, a portion of it (trikes on the paper, on 
which it imprefles beautiful rays. Gold wire gives a 
purple tint, copper a bright green, tin a greenilh yellow, 
lead a pale green, &c. 
A powerful charge of electricity oxydates a confider- 
Vol. VI.. No. 363. 
able length of metallic wire; while galvanifm aCts on 
fucceflive portions of the metal, whenever it is excited 
by a conducting medium. EleCtricity produces all its 
effeCts by one hidden and violent difeharge; while gal¬ 
vanifm operates by its continual current. It is on this 
account, that the fenfations produced by their diverfe 
aCtions, are materially different. The eleCtric (hock, 
from a very fmall jar, operates on the body by a hidden 
and percullive eifeCt; while the one which follows the 
galvanic procefs feems to arife from a conftant current, 
attended by a jarring and tremulous fenfation. 
All finely-drawn metallic wires are rapidly burnt by 
means of a large galvanic battery, the powers of which 
are in general afcertainable by the extent of fine fteel 
wires, fuch as the pendulum fprings of watches, which 
the battery will inftantly render red-hot. This confti- 
tutes the mod correCt galvanometer ; while the other, on 
which we have already touched, ought to be termed a 
galvanifcope. A powerful battery .will induce'a red heat 
on feveral inches of the above fteel wire. 
To deflagrate finely laminated metals, good charcoal 
is the bed medium which can be employed. As the 
fubftance of the metallic leaves, when laminated, is much 
thinner than that of any wires which can be drawn, the 
deflagrations are more brilliant, and the light extremely 
vivid. Gold leaf, having the thicknefs of the 1.282,000th 
part of an inch only, is not merely deflagrated, but is 
likewife completely oxydated, and reduced to a purple 
powder. Silver leaf, which is thicker than gold leaf in 
the proportion of feven to four, is likewife converted 
into an oxyd, and exhibits a beautiful greenilh light. 
We tints fee that, by the powers of galvanic eledtricity, 
two metals which relift: the utmoft force of our furnaces, 
are rapidly oxydated. 
Copper leaf has a thicknefs nearly five times greater 
than that of gold leaf. In its deflagration, red ignited 
particles of copper are detached, on this account, that 
copper requiring a very high temperature before it titles, 
the ignition takes place firft. The copper, before it 
melts, is conftantly red-hot, which is not the cafe with 
tin, lead, &c. The Dutch (liver leaf, a compofition of 
tin and zinc, about ten tiyies as thick as g-old leaf, is de¬ 
flagrated with rapidity. Tin-foil, which is alio a com¬ 
petition of tin and zinc, is about three hundred times 
thicker than gold leaf. Narrow (lips of this fubftance 
are alfo eafily deflagrated. In fhort, all metals, if in a 
due ftate of tenuity, are capable of being deflagrated. 
In a medical view, galvanic ele&ricity certainly merits 
our attention beyond any mere philpfophical refearch ; 
itlafmuch as its peculiar excitation of the animal func¬ 
tions, offers, an inftantaneons and powerful ftimulus in 
many cafes, where other means cannot be fo readily ap¬ 
plied. In the prefent date of our knowledge of the 
principles of galvanifm, it has not been afeertained whe¬ 
ther any particular corporeal derangements are the caufes 
or effects of a change in the refpedtive capacities of the 
difeafed parts for electricity. The afeertainment of this 
point would be a conliderable defideratum in medicine. 
The attion of galvanifm on the mufcular and nervous 
fyftems, is found to.be more violent, in proportion to its 
imenfity, than that of common electricity. The charge 
of a galvanic battery, fo feeble as not to be able to dif- 
turb a gold-leaf eledtrofeope, when propelled, through 
the head, is faid to produce a ftronger fenfation than the 
one which is experienced from one hundred times the 
fame intenfity, produced by a Leyden phial. 
In an age like 4 he prefent, when a flow, and progref- 
five progrefs in the fciences is too apt to be confidered 
as a ftationary date; in an age, in (liort, when a defire 
feems manifefted to colled! the fruits before the flowers 
are formed, the experiments which have, from the mo¬ 
ment they were conceived and made, promifed a fpeedy 
and immediate application to th.e healing art, cannot 
have failed to attraft the particular attention of the pub¬ 
lic; by whom fuch an application was in a manner an- 
5 X ticipated. 
