ELECT 
are brought into contact, the (liver receives a coating of 
copper. " In the explanation of thefe experiments, it is 
neceffary to advert to a point edabliffied by means of the 
eleCtric pile. We know that when water is placed in a 
•circuit of conductors of electricity, between the two ex- 
• tremiiies.of a pile, if the power is fufficient to oxydate one 
of the wires of communication, the wire connected with 
the oppofite extremity aifords hydrogen gas. Since the 
extrication of hydrogen, in this jnftance, is feen to de¬ 
pend on eleCtricity, it is probable that, in other indances, 
electricity may be alfo requilite for its converlion into 
gas. It would appear, therefore, that in the folution of 
a metal, electricity is evolved during the aCtion of the 
acid upon it ; and that the formation of hydrogen gas, 
even in that cafe, depends on a tranfition of eleCtricity 
between the fluid and the metal. We fee, moreover, in 
the firft experiment, that the zinc, without contaCt of 
any other metal, has the power of decompofing water; 
and we can have no reafon to fuppofe that the contaCt of 
the filver produces any new power, but that it ferves 
merely as a conductor of eleCtricity, and thereby occafions 
the formation of hydrogen gas. In the third experiment 
alfo, the iron by itfelf has the power of precipitating 
copper, by means, I prefume, of eleCtricity evolved du¬ 
ring its dilution ; and here likewife the filver, by con¬ 
ducting that eleCtricity, acquires the power of precipi¬ 
tating the copper in its metallic date. The explanation 
here given receives additional confirmation from compa¬ 
rative-experiments which I have made with common elec¬ 
tricity ; for it will be feen that the fame transfer of che¬ 
mical power, and the fame apparent reverfion of the uTual 
order of chemical affinities in the precipitation of copper 
by filver, may be effected by a common eleCtrical machine. 
The machine with which thefe experiments were con¬ 
ducted, confifis of a cylinder feven inches in diameter, 
with a conductor on each fide fixteen inches long, and 
three inches and a half diameter, each furnidied with a 
Aiding electrometer, to regulate the drength of the fpark 
received from them. 
4. Having a wire of fine filver, 1-1 joth of an inch in 
diameter, I coated the middle of it, for two or three 
inches, with fealing-wax, and, by cutting through in the 
middle of the wax, expofed a feCtion of the wire. The 
two coated extremities of the wire, thus divided, were 
immerfed in a folution of fulphat of copper placed in an 
eleCtric circuit between the two conductors ; and fparks, 
taken at one-tenth of an inch didance, were pafled by 
means of them through the folution. After one hundred 
turns of the machine, the wire which communicated with 
(what is called) the negative conductor, had a precipitate 
formed on its furface, which, upon being burnilhed, was 
evidently copper ; but the oppofite wire had no fitch 
coating. Upon reverfing the direction of the current of 
eleCtricity, the order of the phenomena was of courfe re- 
verfed ; the copper being Ihortly re-diffolved by affid- 
ance of the oxydating power of pofitive e^Ctricity, and 
a fimilar precipitate formed on the oppofite wire. 
5. A fimilar experiment made with gold wires i-iooth 
of an inch diameter, in a folution of corrofivc lublimate, 
had the fame fuccefs. The chemical agency, therefore, 
of common eleCtricity is thus proved to be the fame with 
the power excited by chemical means; but, (ince a dif. 
ference has been obferved in the comparative facility 
with which the pile of Volta decompofes water, and pro¬ 
duces other effects of oxydation and de-oxydation of bo¬ 
dies expofed to its aCtion, I have been at fome pains to 
remove this difficulty, and can at lead produce a very 
clofe imitation of the galvanic phenomena by common 
eleCtricity. It has been thought neceffary to employ 
powerful machines and large Leyden jars for the decom- 
polition of water; but, when I confidered that the de- 
compofition mud depend on duly proportioning the 
drength of the charge of electricity to the quantity of 
water, and that the quantity expofed to its action at the 
furface of communication depends on the extent of that 
Vol. VL No. 362, 
R I C I T Y. 427 
furface, I hoped that, by reducing the furface of com¬ 
munication, the decompofition of water might be effected 
by fmaller machines, and with lefs powerful excitation, 
than have hitherto been ufed for that purpofe; and in 
this hope I have not been disappointed. 
6. Having procured a fmall wife of fine gold, and 
given it as fine a point as I could, i infected it into a ca¬ 
pillary glafs'tube ; and, after heating the tube fo as to 
make it adhere to the point, and cover it in every part, 
I gradually ground it down, till, with a pocket lens, I 
could difeern that the point of the gold was expofed. 
'The fuccefs of this method exceeding my expectations* 
I coated feveral wires in the fame manner, and found, 
that when fparks from the conductors before-mentioned 
were made to pafs through water, by means of a point 
fo guarded, a fpark palling to the didance of one-eighth 
of an inch would decompofe water, when the point ex¬ 
pofed did not exceed i-700th of an inch in diameter. 
With another point, which I edimated at i-i^ooth, a 
fucceffion of fparks, one-twentieth of an inch in length, 
afforded a current of fmall bubbles of air. I have (ince 
found that the fame apparatus will decompofe water with 
a wire one-fortieth of an inch diameter, coated in the 
manner before-deferibed, if the fpark from the prime 
conductor pafles to the diftance of four-tenths of an inch 
of air. » 
7. I'n order to try how far the drength of the eleCtric 
fpark might be reduced by a proportional diminution of 
the extremity of the wire, I puffed a folution of gold in 
aqua regia through a capillary tube, and, by heating the 
tube, expelled the acid. There remained a thin film of 
gold lining the inner furface of the tube, which, by 
melting the tube, was converted into a very fine thread 
of gold, through the fubdance of the glafs. When the 
extremity of this thread was made the medium of com- ‘ 
munication through water, I found that the mere cur¬ 
rent of eleCtricity would occafion a dream of very fmall 
bubbles to rile from the extremity of the gold, although 
the wire, by which it communicated with the pofitive or 
negative conductor,.was placed in abfolute contaCt with 
them. Hence it appears, that the decompofition of water 
may take place by common eleCtricity as well as by the 
eleCtric pile, although no difccrnible fparks are produced. 
The appearance of two currents of air may alfo be imi¬ 
tated by occalioning the eleCtricity to pafs by fine points 
of communication on both (ides of the water; but, in 
faCt, the refemblance is not complete ; for, in every way 
in which I have tried it, I obferved, that each wire gave 
both oxygen and hydrogen gas, indead of their being 
formed feparately, as by the eleCtric pile. • I am inclined 
to attribute the difference in this refpeCt to the greater 
intenlity with which it is neceffary to employ common 
ele'Ctricity : for, that pofitive and negative electricity, fo 
excited, have each the fame chemical power as they are 
obferved to have in the eleCtric pile, may be afeertained 
by other means. In the precipitation of copper by fil¬ 
ver, an indance of de-oxydation by negative eleCtricity 
has been mentioned : the oxydating power of pofitive 
eleCtricity may be alfo proved by its effect on vegetable 
blue colours. 
8. Having coloured a card with a drong infufion of 
litmus, I paffed a current of eleCtric fparks along it, by 
means of two fine gpld points, touching it at the didance 
of an inch from each other. The effeCt, as in other cafes, 
depending on the fmallnefs of the quantity of water, was 
" mod difcernible when the card was nearly dry. In this 
date, a very few turns of the machine were fufficient to 
occafion a rednefs at the pofitive wire, very manifed to 
the naked eye. The negative wire, being afterwards 
placed on the fame fpot, foon redored it to its original 
blue colour. By M. Volta’s apparatus, the fame effects 
are produced in much lefs time. Befide the (imilarity 
which has thus been traced between the effeCts of elec¬ 
tricity excited by the common machine and thofe ob¬ 
ferved from the electric pile, I think it appears alfo pro- 
5'T bable 
