ern term physicist.

[3] To whom I am indebted for a copy of the original letter.

Chapter 2.

Early researches: magnetic rotations: liquefaction of gases:
heavy glass: Charles Anderson: contributions to physics.

Oersted, in 1820, discovered the action of a voltaic current on a
magnetic needle; and immediately afterwards the splendid intellect of
Ampere succeeded in showing that every magnetic phenomenon then known
might be reduced to the mutual action of electric currents. The subject
occupied all men's thoughts: and in this country Dr. Wollaston sought
to convert the deflection of the needle by the current into a permanent
rotation of the needle round the current. He also hoped to produce the
reciprocal effect of causing a current to rotate round a magnet. In
the early part of 1821, Wollaston attempted to realise this idea in
the presence of Sir Humphry Davy in the laboratory of the Royal
Institution.[1] This was well calculated to attract Faraday's attention
to the subject. He read much about it; and in the months of July,
August, and September he wrote a 'history of the progress of
electro-magnetism,' which he published in Thomson's 'Annals of
Philosophy.' Soon afterwards he took up the subject of 'Magnetic
Rotations,' and on the morning of Christmas-day, 1821, he called his
wife to witness, for the first time, the revolution of a magnetic needle
round an electric current. Incidental to the 'historic sketch,' he
repeated almost all the experiments there referred to; and these, added
to his own subsequent work, made him practical master of all that was
then known regarding the voltaic current. In 1821, he also touched
upon a subject which subsequently received his closer attention--the
vaporization of mercury at common temperatures; and immediately
afterwards conducted, in company with Mr. Stodart, experiments on the
alloys of steel. He was accustomed in after years to present to his
friends razors formed from one of the alloys then discovered.

During Faraday's hours of liberty from other duties, he took up subjects
of inquiry for himself; and in the spring of 1823, thus self-prompted,
he began the examination of a substance which had long been regarded as
the chemical element chlorine, in a solid form, but which Sir Humphry
Davy, in 1810, had proved to be a hydrate of chlorine, that is, a
compound of chlorine and water. Faraday first analysed this hydrate, and
wrote out an account of its