spended, it always set axially,
that is, from pole to pole.
Faraday called those bodies which were repelled by the poles of a
magnet, diamagnetic bodies; using this term in a sense different from
that in which he employed it in his memoir on the magnetization of
light. The term magnetic he reserved for bodies which exhibited the
ordinary attraction. He afterwards employed the term magnetic to cover
the whole phenomena of attraction and repulsion, and used the word
paramagnetic to designate such magnetic action as is exhibited by iron.
Isolated observations by Brugmanns, Becquerel, Le Baillif, Saigy, and
Seebeck had indicated the existence of a repulsive force exercised by
the magnet on two or three substances; but these observations, which
were unknown to Faraday, had been permitted to remain without extension
or examination. Having laid hold of the fact of repulsion, Faraday
immediately expanded and multiplied it. He subjected bodies of the most
varied qualities to the action of his magnet:--mineral salts, acids,
alkalis, ethers, alcohols, aqueous solutions, glass, phosphorus,
resins, oils, essences, vegetable and animal tissues, and found them
all amenable to magnetic influence. No known solid or liquid proved
insensible to the magnetic power when developed in sufficient strength.
All the tissues of the human body, the blood--though it contains
iron--included, were proved to be diamagnetic. So that if you could
suspend a man between the poles of a magnet, his extremities would
retreat from the poles until his length became equatorial.
Soon after he had commenced his researches on diamagnetism, Faraday
noticed a remarkable phenomenon which first crossed my own path in the
following way: In the year 1849, while working in the cabinet of my
friend, Professor Knoblauch, of Marburg, I suspended a small copper coin
between the poles of an electro-magnet. On exciting the magnet, the coin
moved towards the poles and then suddenly stopped, as if it had struck
against a cushion. On breaking the circuit, the coin was repelled, the
revulsion being so violent as to cause it to spin several times round
its axis of suspension. A Silber-groschen similarly suspended exhibited
the same deportment. For a moment I thought this a new discovery; but on
looking over the literature of the subject, it appeared that Faraday
had observed, multiplied, and explained the same effect during his
researches on diamagnetism. His explanation was b
|