[Footnote: Paper lately read before the Society of Telegraph Engineers
and Electricians.]

By Professor D. E. HUGHES, F.R.S., Vice-President.

NEUTRALITY.


The apparatus needed for researches upon evident external polarity
requires no very great skill or thought, but simply an apparatus to
measure correctly the force of the evident repulsion or attraction; in
the case of neutrality, however, the external polarity disappears, and
we consequently require special apparatus, together with the utmost care
and reflection in its use.

From numerous researches previously made by means of the induction
balance, the results of which I have already published, I felt convinced
that in investigating the cause of magnetism and neutrality I should
have in it the aid of the most powerful instrument of research ever
brought to bear upon the molecular construction of iron, as indeed of
all metals. It neglects all forces which do not produce a change in the
molecular structure, and enables us to penetrate at once to the interior
of a magnet or piece of iron, observing only its peculiar structure
and the change which takes place during magnetization or apparent
neutrality.

The induction balance is affected by three distinct arrangements of
molecular structure in iron and steel, by means of which we have
apparent external neutrality.