many ways without any special direction from me.

Well, the magnet attracts the nail, and the nail attracts a second
one. This proves that the nail in contact with the magnet has had the
magnetic quality developed in it by that contact. If it be withdrawn
from the magnet its power to attract its fellow nail ceases. Contact,
however, is not necessary. A sheet of glass or paper, or a space of
air, may exist between the magnet and the nail; the latter is still
magnetised, though not so forcibly as when in actual contact. The
nail thus presented to the magnet is itself a temporary magnet. That
end which is turned towards the magnetic pole has the opposite
magnetism of the pole which excites it; the end most remote from the
pole has the same magnetism as the pole itself, and between the two
poles the nail, like the magnet, possesses a magnetic equator.

Conversant as you now are with the theory of magnetic fluids, you have
already, I doubt not, anticipated me in imagining the exact condition
of an iron nail under the influence of the magnet. You picture the
iron as possessing the neutral fluid in abundance; you picture the
magnetic pole, when brought near, decomposing the fluid; repelling the
fluid of a like kind with itself, and attracting the unlike fluid;
thus exciting in the parts of the iron nearest to itself the opposite
polarity. But the iron is incapable of becoming a permanent magnet.
It only shows its virtue as long as the magnet acts upon it. What,
then, does the iron lack which the steel possesses? It lacks coercive
force. Its fluids are separated with ease; but, once the separating
cause is removed, they flow together again, and neutrality is
restored. Imagination must be quite nimble in picturing these
changes--able to see the fluids dividing and reuniting, according as
the magnet is brought near or withdrawn. Fixing a definite pole in
your mind, you must picture the precise arrangement of the two fluids
with reference to this pole, and be able to arouse similar pictures in
the minds of your pupils. You will cause them to place magnets and
iron in various positions, and describe the exact magnetic state of
the iron in each particular case. The mere facts of magnetism will
have their interest immensely augmented by an acquaintance with the
principles whereon the facts depend. Still, while you use this theory
of magnetic fluids to track out the phenomena and link them together,
you will not forg