en you have done
so long enough the battery is charged again and ready to discharge.

I am not going to tell you very much about the storage battery but you
ought to know a little about it if you are to own and run one with your
radio set. When it is all charged and ready to work, the negative plate
is a lot of soft spongy lead held in place by a frame of harder lead.
The positive plate is a lead frame with small squares which are filled
with lead peroxide, as it is called. This is a substance with molecules
formed of one lead atom and two oxygen atoms. Why the chemists call it
lead peroxide instead of just lead oxide I'll tell you some other time,
but not in these letters.

Between the two plates is a wood separator to keep pieces of lead from
falling down between and touching both plates. You know what would
happen if a piece of metal touched both plates. There would be a short
circuit, that is, a sort of a short cut across lots by which some of the
electrons from the negative plate could get to the positive plate
without going along the wires which we want them to travel. That's why
there are separators.

The two plates are in a jar of sulphuric acid solution. The sulphuric
acid has molecules which split up in solution, as you remember, into
hydrogen ions and the ions which we called "sulphate." In my gravity
battery the sulphate ions used to coax the zinc ions away into the
solution. In the storage battery on the other hand the sulphate ions can
get to most of the lead atoms because the lead is so spongy. When they
do, they form lead sulphate right where the lead atoms are. They don't
really need whole lead atoms, because they have two more electrons than
they deserve, so there are two extra electrons for every molecule of
lead sulphate which is formed. That's why the spongy lead plate is
negative.

The lead sulphate won't dissolve, so it stays there on the plate as a
whitish coating. Now see what that means. What are the hydrogen ions
going to do? As long as there was sulphuric acid in the water there was
plenty of sulphate ions for them to associate with as often as they met;
and they would meet pretty often. But if the sulphate ions get tied up
with the lead of the plate there will be too many hydrogen ions left in
the solution. Now what are the hydrogen ions to do? They are going to
get as far away from each other as they can, for they are nothing but
protons; and protons don't like to associate. They only s