Do not
add water to the acid.
The cell is charged by placing the zinc in the paper tube and both
placed into the tin can. Connect the two wires and pour the dilute
acid into the porous cell around the zinc, and then immediately
turn the blue vitriol solution into the can outside the paper cup.
A current generates at once and metallic copper begins to deposit
on the inside of the can. It is best to let the action continue
for a half hour or so before putting the cell into use.
[Illustration: Daniell Cell]
Several hours working will be required before the film of copper
becomes sufficiently thick to protect the tin from corrosion when
the cell stands idle. For this reason it will be necessary to pour
out the blue vitriol solution into another receptacle immediately
after through using, as otherwise the tin would be soon eaten full
of holes. The porous cup should always be emptied after using to
prevent the diffusion of the blue vitriol solution into the cup,
and the paper tube must be well rinsed before putting away to dry.
This makes one of the most satisfactory battery cells on account
of the constancy of its current, running for hours at a time
without materially losing strength, and the low cost of
maintenance makes it especially adapted for amateurs' use.
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