It was not then
any property possessed permanently by the bismuth, and which merely
required the development of magnetism to act upon it, that caused the
repulsion; for then the repulsion would have been simply proportional to
the strength of the influencing magnet, whereas experiment proved it to
augment as the square of the strength. The capacity to be repelled was
therefore not inherent in the bismuth, but induced. So far an identity
of action was established between magnetic and diamagnetic bodies.
After this the deportment of magnetic bodies, 'normal' and 'abnormal';
crystalline, amorphous, and compressed, was compared with that of
crystalline, amorphous, and compressed diamagnetic bodies; and by a
series of experiments, executed in the laboratory of this Institution,
the most complete antithesis was established between magnetism and
diamagnetism. This antithesis embraced the quality of polarity,--the
theory of reversed polarity, first propounded by Faraday, being proved
to be true. The discussion of the question was very brisk. On the
Continent Professor Wilhelm Weber was the ablest and most successful
supporter of the doctrine of diamagnetic polarity; and it was with an
apparatus, devised by him and constructed under his own superintendence,
by Leyser of Leipzig, that the last demands of the opponents of
diamagnetic polarity were satisfied. The establishment of this point was
absolutely necessary to the explanation of magne-crystallic action.

With that admirable instinct which always guided him, Faraday had seen
that it was possible, if not probable, that the diamagnetic force acts
with different degrees of intensity in different directions, through
the mass of a crystal. In his studies on electricity, he had sought an
experimental reply to the question whether crystalline bodies had not
different specific inductive capacities in different directions, but
he failed to establish any difference of the kind. His first attempt
to establish differences of diamagnetic action in different directions
through bismuth, was also a failure; but he must have felt this to be
a point of cardinal importance, for he returned to the subject in 1850,
and proved that bismuth was repelled with different degrees of force in
different directions. It seemed as if the crystal were compounded of
two diamagnetic bodies of different strengths, the substance being more
strongly repelled across the magne-crystallic axis than along it. The
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