<s>
upright	O
=	O
1.2	O
|thumb|Schematic	O
diagram	O
of	O
a	O
copper	O
–	O
zinc	B-Application
voltaic	B-Architecture
pile	I-Architecture
.	O
</s>
<s>
The	O
copper	O
and	O
zinc	B-Application
discs	O
were	O
separated	O
by	O
cardboard	O
or	O
felt	O
spacers	O
soaked	O
in	O
salt	O
water	O
(	O
the	O
electrolyte	O
)	O
.	O
</s>
<s>
Volta	O
's	O
original	O
piles	O
contained	O
an	O
additional	O
zinc	B-Application
disk	O
at	O
the	O
bottom	O
,	O
and	O
an	O
additional	O
copper	O
disk	O
at	O
the	O
top	O
.	O
</s>
<s>
The	O
voltaic	B-Architecture
pile	I-Architecture
was	O
the	O
first	O
electrical	O
battery	O
that	O
could	O
continuously	O
provide	O
an	O
electric	O
current	O
to	O
a	O
circuit	O
.	O
</s>
<s>
The	O
voltaic	B-Architecture
pile	I-Architecture
then	O
enabled	O
a	O
rapid	O
series	O
of	O
other	O
discoveries	O
including	O
the	O
electrical	O
decomposition	O
(	O
electrolysis	O
)	O
of	O
water	O
into	O
oxygen	O
and	O
hydrogen	O
by	O
William	O
Nicholson	O
and	O
Anthony	O
Carlisle	O
(	O
1800	O
)	O
and	O
the	O
discovery	O
or	O
isolation	O
of	O
the	O
chemical	O
elements	O
sodium	O
(	O
1807	O
)	O
,	O
potassium	O
(	O
1807	O
)	O
,	O
calcium	O
(	O
1808	O
)	O
,	O
boron	O
(	O
1808	O
)	O
,	O
barium	O
(	O
1808	O
)	O
,	O
strontium	O
(	O
1808	O
)	O
,	O
and	O
magnesium	O
(	O
1808	O
)	O
by	O
Humphry	O
Davy	O
.	O
</s>
<s>
the	O
Daniell	B-Algorithm
cell	I-Algorithm
and	O
Grove	B-Algorithm
cell	I-Algorithm
)	O
until	O
the	O
advent	O
of	O
the	O
dynamo	B-Language
(	O
the	O
electrical	O
generator	O
)	O
in	O
the	O
1870s	O
.	O
</s>
<s>
In	O
1800	O
,	O
Volta	O
stacked	O
several	O
pairs	O
of	O
alternating	O
copper	O
(	O
or	O
silver	O
)	O
and	O
zinc	B-Application
discs	O
(	O
electrodes	O
)	O
separated	O
by	O
cloth	O
or	O
cardboard	O
soaked	O
in	O
brine	O
to	O
increase	O
the	O
total	O
electromotive	O
force	O
.	O
</s>
<s>
When	O
the	O
top	O
and	O
bottom	O
contacts	O
were	O
connected	O
by	O
a	O
wire	O
,	O
an	O
electric	O
current	O
flowed	O
through	O
the	O
voltaic	B-Architecture
pile	I-Architecture
and	O
the	O
connecting	O
wire	O
.	O
</s>
<s>
The	O
voltaic	B-Architecture
pile	I-Architecture
,	O
together	O
with	O
many	O
scientific	O
instruments	O
that	O
belonged	O
to	O
Alessandro	O
Volta	O
,	O
are	O
preserved	O
in	O
the	O
University	O
History	O
Museum	O
of	O
the	O
University	O
of	O
Pavia	O
,	O
where	O
Volta	O
taught	O
from	O
1778	O
to	O
1819	O
.	O
</s>
<s>
thumb|upright	O
=	O
1.2	O
|Drawing	O
of	O
the	O
voltaic	B-Architecture
pile	I-Architecture
in	O
different	O
configurations	O
,	O
from	O
the	O
letter	O
sent	O
from	O
Alessandro	O
Volta	O
to	O
Joseph	O
Banks	O
.	O
</s>
<s>
On	O
learning	O
of	O
the	O
voltaic	B-Architecture
pile	I-Architecture
,	O
William	O
Nicholson	O
and	O
Anthony	O
Carlisle	O
used	O
it	O
to	O
discover	O
the	O
electrolysis	O
of	O
water	O
.	O
</s>
<s>
He	O
also	O
used	O
the	O
voltaic	B-Architecture
pile	I-Architecture
to	O
decompose	O
chemicals	O
and	O
to	O
produce	O
new	O
chemicals	O
.	O
</s>
<s>
William	O
Hyde	O
Wollaston	O
showed	O
that	O
electricity	O
from	O
voltaic	B-Architecture
piles	I-Architecture
had	O
identical	O
effects	O
to	O
those	O
of	O
electricity	O
produced	O
by	O
friction	O
.	O
</s>
<s>
In	O
1802	O
Vasily	O
Petrov	O
used	O
voltaic	B-Architecture
piles	I-Architecture
in	O
the	O
discovery	O
and	O
research	O
of	O
electric	O
arc	O
effects	O
.	O
</s>
<s>
Humphry	O
Davy	O
and	O
Andrew	O
Crosse	O
were	O
among	O
the	O
first	O
to	O
develop	O
large	O
voltaic	B-Architecture
piles	I-Architecture
.	O
</s>
<s>
Because	O
Volta	O
believed	O
that	O
the	O
electromotive	O
force	O
occurred	O
at	O
the	O
contact	O
between	O
the	O
two	O
metals	O
,	O
Volta	B-Architecture
's	I-Architecture
piles	I-Architecture
had	O
a	O
different	O
design	O
than	O
the	O
modern	O
design	O
illustrated	O
on	O
this	O
page	O
.	O
</s>
<s>
His	O
piles	O
had	O
one	O
extra	O
disc	O
of	O
copper	O
at	O
the	O
top	O
,	O
in	O
contact	O
with	O
the	O
zinc	B-Application
,	O
and	O
one	O
extra	O
disc	O
of	O
zinc	B-Application
at	O
the	O
bottom	O
,	O
in	O
contact	O
with	O
the	O
copper	O
.	O
</s>
<s>
Expanding	O
on	O
Volta	O
's	O
work	O
and	O
the	O
electro-magnetism	O
work	O
of	O
his	O
mentor	O
Humphry	O
Davy	O
,	O
Michael	O
Faraday	O
utilized	O
both	O
magnets	O
and	O
the	O
voltaic	B-Architecture
pile	I-Architecture
in	O
his	O
experiments	O
with	O
electricity	O
.	O
</s>
<s>
The	O
modern	O
,	O
atomistic	O
understanding	O
of	O
a	O
cell	O
with	O
zinc	B-Application
and	O
copper	O
electrodes	O
separated	O
by	O
an	O
electrolyte	O
is	O
the	O
following	O
.	O
</s>
<s>
When	O
the	O
cell	O
is	O
providing	O
an	O
electrical	O
current	O
through	O
an	O
external	O
circuit	O
,	O
the	O
metallic	O
zinc	B-Application
at	O
the	O
surface	O
of	O
the	O
zinc	B-Application
anode	O
is	O
oxidized	O
and	O
dissolves	O
into	O
the	O
electrolyte	O
as	O
electrically	O
charged	O
ions	O
(	O
Zn2+	O
)	O
,	O
leaving	O
2	O
negatively	O
charged	O
electrons	O
(	O
)	O
behind	O
in	O
the	O
metal	O
:	O
</s>
<s>
This	O
reaction	O
is	O
called	O
oxidation	B-Operating_System
.	O
</s>
<s>
While	O
zinc	B-Application
is	O
entering	O
the	O
electrolyte	O
,	O
two	O
positively	O
charged	O
hydrogen	O
ions	O
(	O
H+	O
)	O
from	O
the	O
electrolyte	O
accept	O
two	O
electrons	O
at	O
the	O
copper	O
cathode	O
surface	O
,	O
become	O
reduced	O
and	O
form	O
an	O
uncharged	O
hydrogen	O
molecule	O
(	O
H2	O
)	O
:	O
</s>
<s>
This	O
reaction	O
is	O
called	O
reduction	B-Operating_System
.	O
</s>
<s>
The	O
electrons	O
used	O
from	O
the	O
copper	O
to	O
form	O
the	O
molecules	O
of	O
hydrogen	O
are	O
made	O
up	O
by	O
an	O
external	O
wire	O
or	O
circuit	O
that	O
connects	O
it	O
to	O
the	O
zinc	B-Application
.	O
</s>
<s>
The	O
hydrogen	O
molecules	O
formed	O
on	O
the	O
surface	O
of	O
the	O
copper	O
by	O
the	O
reduction	B-Operating_System
reaction	O
ultimately	O
bubble	O
away	O
as	O
hydrogen	O
gas	O
.	O
</s>
<s>
Copper	O
does	O
act	O
as	O
a	O
catalyst	O
for	O
the	O
hydrogen-evolution	O
reaction	O
,	O
which	O
otherwise	O
could	O
occur	O
equally	O
well	O
directly	O
at	O
the	O
zinc	B-Application
electrode	O
without	O
current	O
flow	O
through	O
the	O
external	O
circuit	O
.	O
</s>
<s>
When	O
no	O
current	O
is	O
drawn	O
from	O
the	O
pile	O
,	O
each	O
cell	O
,	O
consisting	O
of	O
zinc/electrolyte/copper	O
,	O
generates	O
0.76	O
V	O
with	O
a	O
brine	O
electrolyte	O
.	O
</s>
<s>
A	O
number	O
of	O
high-voltage	O
dry	O
piles	O
were	O
invented	O
between	O
the	O
early	O
19th	O
century	O
and	O
the	O
1830s	O
in	O
an	O
attempt	O
to	O
determine	O
the	O
source	O
of	O
electricity	O
of	O
the	O
wet	O
voltaic	B-Architecture
pile	I-Architecture
,	O
and	O
specifically	O
to	O
support	O
Volta	O
's	O
hypothesis	O
of	O
contact	O
tension	O
.	O
</s>
<s>
One	O
form	O
of	O
dry	O
pile	O
is	O
the	O
Zamboni	B-Algorithm
pile	I-Algorithm
.	O
</s>
<s>
The	O
dry	O
pile	O
could	O
be	O
referred	O
to	O
as	O
the	O
ancestor	O
of	O
the	O
modern	O
dry	B-Algorithm
cell	I-Algorithm
.	O
</s>
