(1) 'By a diamagnetic,' says Faraday, 'I mean a body through
which lines of magnetic force are passing, and which does
not by their action assume the usual magnetic state of iron
or loadstone.' Faraday subsequently used this term in a
different sense from that here given, as will immediately
appear.

(2) The power of double refraction conferred on the centre
of a glass rod, when it is caused to sound the fundamental
note due to its longitudinal vibration, and the absence of
the same power in the case of vibrating air (enclosed in a
glass organ-pipe), seems to be analogous to the presence and
absence of Faraday's effect in the same two substances.
Faraday never, to my knowledge, attempted to give, even in
conversation, a picture of the molecular condition of his
heavy glass when subjected to magnetic influence. In a
mathematical investigation of the subject, published in the
Proceedings of the Royal Society for 1856, Sir William
Thomson arrives at the conclusion that the 'diamagnetic' is
in a state of molecular rotation.