y+ the same nuinber of plates, whatever was their size ; 
=" but he perceived Fourcroy’s observation to be correct, 
that it was eens to vot latge plates to burn the 
metals. He formed a pile of large plates of zinc and 
copper, and succeeded in fusing iron wires of consider- 
able thickness ; he at last even fused a wire of platina. 
He found that a battery, consisting of 137} square 
feet of coated glass, was cha by a galvanic appa- 
ratus to an intensity equal to itself, in 1-20th of a ses 
cond ; a cireumstance which proves the amazing velo« 
city of the fluid. He conceived that the energy of the 
ile was much ry aE when it was kept in an insu~ 
state, and likewise when a solution of the muri- 
ate of ammonia was oséd between the copper and 
zine plates. See Ann. de Chim. xl. 289. 
fonof °. We havealready noticed the discovery of Mr Cruick- 
le de- Shanks, that the pile acted mote powerfully in oxygen 
ates the gas than-in the air of the atmosphere; and an observa- 
tion the converse of this, was made by Biot and Cuvier, 
whith confirmed the relation between the action of 
the apparatus and the chemical state of the fluid in 
which it is immersed. When the pile was inclosed in 
a limited quantity of air, they found that, after some 
time, the air was sensibly deoxidated. See Ann. de 
Chim. xxxix. 242, ‘ 
eof o- ' The discoveries that were made with the galvanic pile, 
> ahaa A ae by the English chemists, completely esta- 
shed some of the most important points which had 
previously been subjects of doubt or controversy. Ani~ 
mal electricity, as produced in the original experiments 
of Galvani, and wards in those of Valli, Fowler, 
Volta, and others, was now admitted to depend upon 
nothing adherent in, or attached to, the animal body, 
_* _ but upon an agent, called into action by external causes, 
F and manifesting itself in consequence of the delicate 
sensibility of the nervous and muscular'systems. This 
agent was now generally recognized as being identical 
with electricity, conducted by the same substances, 
possessing the same ies, and, in short, subject 
to the same physical laws. It was conjectured, that 
the apparent difference between electricity, as excited 
ne and by the pile; depended upon the 
different states of intensity in which they exist; the 
electricity of the machine being in a much higher state 
— pw by the pile, although this latter is ae, 
isengaged in greater quantity. This may be regard- 
ed as the state of the lence a 1801 + eer ale then 
until the grand discovery of Sir H. Davy, which we 
have marked out as the third era, the attention of the 
the don € i " ists, woe devoted themselves to 
t artment of natural philosophy, was j di- 
rected to improving or modifying the Pe. on 
partly to hypothetical discussions, respecting the na~ 
ture of the action, and its connexion with chemical af: 
finity. This latter topic, in conformity with the plan 
which we laid down, will be treated more at length in 
the Second Part of the Article. A number of new facts 
were, however, from time to time, discovered, which 
we shall proceed to detail; and in order to preserve 
the historical order, we shall also briefly touch upon 
bec 9 theory that are to be considered more fully 
A memoir appeared about this time from M. Biot, 
which contains some important observations on the rela= 
tive effects of the different kinds of apparatus, especially 
with regard to the size of the plates that enter into 
their composition. Electricity is known to be dischar- 
by points,. ard to be retained extensive sur- 
faces; and frem this circumstance he conceives; that the 
3 ob- 
ithe size 
GALVANISM. 
85 
smallei the plates are, the more rapid will be the cir- History. 
culation of the fluid; large plates furnish a greater ““y—-” 
quantity of the fluid, but it is less rapid in its motion; 
smaller plates, on the contrary, furnish less fluid, but 
it passes with more rapidity through the different parts 
of the apparatus. Hence what was spoken of by Ni- 
cholgon and others, as constituting the intensity of the 
fluid, is resolved by Biot into the velocity of its mo- pifteres: 
tion. The different operations of the pile are different- velocity of 
ly affected by these two properties. The taste, the the electri- 
ash, and the shock, exist nearly in the same degree, “'Y 
and all depend principally upon the velocity; while the 
combustion of the metals is more influenced by the 
at of the electricity. The electrical attractions 
also depend upon the quantity of fluid, arid are there~ 
fore more perceptible when large plates are usetl. It is 
observed that a pile composed of small plates affords 
very pungent shocks, but is more quickly exhausted. 
It was before stated; that Biot had perceived the pile 
to deoxidate a portion of air in which it was confined ; 
and he now informs us, that the effect was produced 
more rapidly when the ends of the pile were made to 
communicate by intervening wires. The general con- 
clusions with which he sums up this interesting paper, 
are, that the galvanic fluid resembles the electric in the 
tepulsive property of its particles, and that the diffe- 
rent phenomena —— _— variations in the quanti« 
ty and velocity of the fluid. See Jourr. dé Phys. 
i, 264, 
- An elaborate set of experiments was published about Lehot’s ob- 
this period by Lehot, on the direction of the galvanic servations 
current. This subject had also occupied the attention ° the di- 
of Biot, and it was generally admitted that its course Fetion of " 
was from the zinc plate, across the fluid, to the silver See 
or copper plate. See Journ. de Phys. li, 135. 
A circtmstance of ‘some importance in our view 
the action of the pile, was pointed out by Erman 
Berlin ; he remarks, that the detion takes place, hot > ies of 
between the metals, but between the metal and the the exire. 
fluid ; therefore, in designating the end of the’ pile, we mities. 
should say that the zinc end is the negative, and the 
copper the positive. Nicholson and Cruickshanks sup- 
posed the apparatus to be constructed copper, zine; 
fluid; but we should say, zinc, fluid, copper, as in this 
arrangement we have the complete circle. (Journ. Phys: 
liii, 121.) A similar remark was made by Dr Priest- 
ley, who was at this time performing experiments on 
alvanism in America: He says, that no alteration is 
produced in the apparatus by whatever metal is placed 
at the ends beyond the reach of the fluid. Most of the 
phenomena of common electricity had been imitated by 
the electricity of the pile, except that of attraction ; 
and Gautherot now succeeded in contriving an appara= Gautherot 
tas for producing this effect. It consisted of two de~ on galvanic 
licate wires, which hung loose from the extremities of attraction. 
the pile; whew they were brought near together, @ 
le approximation was perceived, and they were 
found to adhere with a degree of force. See Ann. de 
Chim. xxxix. 203. A Pe mer A a 
Tt does not r that Volta himse icipated, in v 
any degree, in the various discoveries that swore: rasihe —-< 
by mieans of his apparatus, or that he employed any electrical 
means for improving or altering its original form. He hypothesis. 
seems’ to have interested himself solely im defending the 
hypothesis, which” he had propased to'account for its 
operation, and which mdeed may be considered as ha~ 
@ led to its construction. His opinion, that the pri- 
mary action was electrical, and that it depended upon 
a change in the distribution of the electric fluid, was 
of Erman’s 
of Temark 
on the 
Priestley’s, 
