t. This requirement was complied with.

Cylinders of antimony were substituted for those of bismuth. This
metal is a better conductor of electricity, but less strongly
diamagnetic than bismuth. If therefore the action referred to be due
to induced currents we ought to have it greater in the case of
antimony than with bismuth; but if it springs from a true diamagnetic
polarity, the action of the bismuth ought to exceed that of the
antimony. Experiment proves this to be the case. Hence the
deflection produced by these metals is due to their diamagnetic, and
not to their conductive capacity. Copper cylinders were next
examined: here we have a metal which conducts electricity fifty times
better than bismuth, but its diamagnetic power is nearly null; if the
effects be due to induced currents we ought to have them here in an
enormously exaggerated degree, but no sensible deflection was produced
by the two cylinders of copper.

It has also been proposed by the opponents of diamagnetic polarity to
coat fragments of bismuth with some insulating substance, so as to
render the formation of induced currents impossible, and to test the
question with cylinders of these fragments. This requirement was also
fulfilled. It is only necessary to reduce the bismuth to powder and
expose it for a short time to the air to cause the particles to become
so far oxidised as to render them perfectly insulating. The
insulating power of the powder was exhibited experimentally;
nevertheless, this powder, enclosed in glass tubes, exhibited an
action scarcely less powerful than that of the massive bismuth
cylinders.

But the most rigid proof, a proof admitted to be conclusive by those
who have denied the antithesis of magnetism and diamagnetism, remains
to be stated. Prisms of the same heavy glass as that with which the
diamagnetic force was discovered, were substituted for the metallic
cylinders, and their action upon the magnet was proved to be precisely
the same in kind as that of the cylinders of bismuth. The enquiry was
also extended to other insulators: to phosphorus, sulphur, nitre,
calcareous spar, statuary marble, with the same invariable result:
each of these substances was proved to be polar, the disposition of
the force being the same as that of bismuth and the reverse of that of
iron. When a bar of iron is set erect, its lower end is known to be a
north pole, and its upper end a south pole, in virtue of the earth's
induction