84 
History» were made to communicate by means of the fingers, or 
a moist substance, and it was found that the oxygen 
‘and hydrogen were evolved as usual. He next inquired 
whether it was necessary for the effect that the wires 
should-be in contact with the ends of the pile ; and in 
order to prove this point, slips of muscular fibre were 
in d between the wires and the ends of the pile. 
The result of this’ disposition was that the gases were 
disengaged, but in a reverse. order ; the hydrogen now 
ding from the wire connected with the ainc end 
of the pile, and the oxygen from the silver or copper 
wire. “ 
These experiments, which at the time when th 
were performed seemed most extraordinary, and a 
most inexplicable, were succeeded by others equally 
curious, in which Sir H. Davy produced the galvanic 
effect, by a new combination of substances. He found 
that charcoal was capable of conducting the influence 
and of decomposing water, the copper end giving out 
New com- 
binations, 
hydrogen, holding a little carbon in solution ; the zine’ 
end did not produce any considerable quantity of gas, 
the carbonic acid which was produced being absorbed 
by the water, in which the charcoal was immersed. He 
formed a pile of zinc and charcoal, which acted with 
considerable energy, and he afterwards. discovered that: 
a pile may be constructed of only one metal, with dif- 
ferent fluids applied to its two surfaces, one of them ca- 
pable of oxidating the metal, the other of preventing 
the effect of oxidation, the two fluids being separated 
from each other by water. The series which he em- 
ployed was metal, diluted nitric acid, water, sulphuret 
of potash, and then again metal. In a subsequent train 
Pile of one 
‘metal. 
Pile of of experiments, he proceeded still farther, and composed 
chareoal, 2 pile without any metal, but consisting solely of pieces 
without of charcoal, having their different surfaces exposed to 
metal. _the action of different fluids. 
Pile will Sir H. Davy also made some very inrportant obser- 
notact with vations on the nature of the fluid inter d- between 
pure water. the plates of the pile. If the water that is employed be 
perfectly pure, containing no acid, salt, or gas, the ap- 
paratus is incapable of acting. He found that its ener- 
gy was in ctor to the rapidity with which the 
oxidation of the metal advances, and consequently was 
most energetic when nitric acid was made use of. In 
pursuance of this opinion, he discovered, that the pile 
can act in vacuo, if an acid be interposed between the 
plates. See Nicholson’s Journal, 4to. iv. 275. 326. 337. 
344.3 and v. 78. 341. 
About this period, Dr Wollaston began to investigate 
the subject of galvanism, and read a paper to the Royal 
Society of London, which displays great marks of sa- 
gacity and penetration. He observes that the energy 
of the apparatus seems to be in proportion te the tens 
deney which one of the metals has to be acted upon by 
the interposed fluid, An experiment is related, not 
very unlike some of those which had been previously 
performed by Fabroni. If a plate of zinc and a plate 
of silver be’ immersed in diluted sulphurie acid, and 
kept asunder, the silver is not affected, but the zine 
begins to decompose the water, and to evolve: hydrogen. 
If the plates be now placed in contact, the silver dis+ 
charges hydrégen, and the zine continues. as before’ to 
be dissolved. From these, and other analogous facts, 
he concludes, that whenever a metal is dissolved by an 
acid, electricity is disengaged. He extends this prin- 
ciple to the action of the electrical machine, which he 
conceives has its power increased by applying an amal- 
gam to the cushion, into: the composition of which a 
metal enters which is readily oxideted, As a farther 
4 
‘Wollaston’s 
experi- 
ments, 
Electricity 
disengaged. 
by metals 
dissolved in 
acid, 
GALVANIS™ 
illustration of the same principle, he found, that the 
machine will not act when immersed in carbonic acid 
sae Nicholson had su, the opinion, that the  Electricit 
electricity of the pile di from that of the machine, of the pil 
in consequence of the latter being in a state of higher ™ 
intensity, but in less tity ; the former of course it 
being in greater quantity, but of low intensity. Dr intensity, 
Wollaston coincided in:this idea, and supposed that it 
might explain the difference between the operation of 
the two instruments. It had been long known that’ 
water might be yt iets the electric shock, but: 
the effect differs from that of the pile, the two gases 
being separated promiscuonsly from both ends of the. 
wire, not as when the pile is employed, the oxygen from 
one end, arid the hydrogen from the other. But Dr Decomp 
Wollaston succeeded in producing the galvanic. effect “*'* 2 
on water by common electricity, so as for ours the gases 
. This he ace ished by coating two silver 
wires, so that the ends of only were exposed. He: 
then connected these wires with the two conductors of 
the electrical machine, and. passed the spark, from one’ 
to the other, through a solution of a salt of copper; the’ 
negative wire was found to be covered with a metallie 
coating, as if it had been connected with the copper or 
silver end of the pile. See Piil, Trans. 1801, p. 427. 
Paige cm dogs gi nc this time, discovered that he ns. 
e pile possesses a powerful effect in burning me-' burn 
tallic leaves. He pote & aninstrement of lnageplaees of set r 
zine and copper, and fixed golddeaf to the zinc end ; ! 
then by ones it in contact with the silver end, the : 
leaf was rapidly consumed, the process being attended 
by a beautiful ion of coloured light. 
and copper leaves* were barned’ in 
Silver; tin, 
. Sead e oa ane 
each giving out a brilliant tinged a 
pare attra (Nicholson’s Journal, vol. nt 238) The °° 
repetition of these experiments on the combustion of Fourcto 
metals, led F rst to a curious discovery, that the discovers 
energy of the shock is not increased by the size of the (5.So0 
plates, but by the number of the repetitions ; while the plates. 
same extent of surface, arranged in the form of a few , 
large plates, readily consumed the metallic leaves, but 
had only a comparatively small effect’ on the sensations. 
(Ann. de mt xxxix. 108.) As the’ action of the 
ile was generally admitted to d upon electricity; 
valiotte attempts "were made, oy liveett aie tomciale 
lists, to charge the Leyden phial, and Mr Cruiekshanks Cruick- — 
at length accomplished it. It was now also a 
agreed, that the extremity of the pile which gave owt Pio) 
oxygen, was in the state of positive electricity, amd the phia, 
end which disengaged hydrogen im the negative state. 
It became a curious subject of investigation to ascers Van Ma 
tain what was the precise difference he rare the ya 7 7 
tric fluid, as generated by the pile, as diseng: «tbe 
by the common machine per Be Van Marum entered galvnil 
upon a series of experiments, i which the action of 
the pile was compared with that of the great Teylerian 
machine at Haarlem. He succeeded in charging, net 
only single jars, but whole batteries, by the pile; and 
they were always charged to the same‘ degree of intet- 
sity with that which the pile itself indicated to am elee- 
trometer placed upon it. He found that the zine end 
of the pile communicated positive electricity to the side 
of the jar or'battery with which it was in contact, and 
the copper end the reverse. No perceptible difference 
could be experienced. between shocks of the same in- 
tensity given’ by ajar or by the battery; Whether they 
were charged by the pile or by the maehine. Hefound 
that the intensity of the pile was always the same from 
