was magnetised, but which then
neutralised each other by their coalescence. And if you test your
magnet, after it has excited a hundred pieces of steel, you will find
that it has lost no force--no more, indeed, than I should lose, had my
words such a magnetic influence on your minds as to excite in them a
strong resolve to study natural philosophy. I should rather be the
gainer by my own utterance, and by the reaction of your fervour. The
magnet also is the gainer by the reaction of the body which it
magnetises.

Look now to your excited piece of steel; figure each molecule with its
opposed fluids spread over its opposite faces. How can this state of
things be permanent? The fluids, by hypothesis, attract each other;
what, then, keeps them apart? Why do they not instantly rush together
across the equator of the atom, and thus neutralise each other? To
meet this question philosophers have been obliged to infer the
existence of a special force, which holds the fluids asunder. They
call it _coercive force_; and it is found that those kinds of steel
which offer most resistance to being magnetised--which require the
greatest amount of 'coercion' to tear their fluids asunder--are the
very ones which offer the greatest resistance to the reunion of the
fluids, after they have been once separated. Such kinds of steel are
most suited to the formation of _permanent_ magnets. It is manifest,
indeed, that without coercive force a permanent magnet would not be at
all possible.

Probably long before this you will have dipped the end of your magnet
among iron filings, and observed how they cling to it; or into a
nail-box, and found how it drags the nails after it. I know very well
that if you are not the slaves of routine, you will have by this time
done many things that I have not told you to do, and thus multiplied
your experience beyond what I have indicated. You are almost sure to
have caused a bit of iron to hang from the end of your magnet, and you
have probably succeeded in causing a second bit to attach itself to
the first, a third to the second; until finally the force has become
too feeble to bear the weight of more. If you have operated with
nails, you may have observed that the points and edges hold together
with the greatest tenacity; and that a bit of iron clings more firmly
to the corner of your magnet than to one of its flat surfaces. In
short, you will in all likelihood have enriched your experience in