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3 70 FRAGMENTS OF SCIENCE.

short, you will, in all likelihood, have enriched your expe-
rience in many ways without any special direction from
me.

Well, the magnet attracts the nail, and that 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 If it be Withdrawn from the magnet, its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 magnetized, though not so forcibly as when
in actual contact. The nail then presented to the magnet
is itself a temporary magnet. That end which is turned
toward 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 be-
tween 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 the iron under the in-
fluence 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. Your imagination must be quite nimble in
picturing these changes. You must be able to see the
fluids dividing and reuniting according as the~ magnet is

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