Chemistry in London Faraday's earliest chemical work was as an assistant to
Humphry Davy. Faraday was involved in the study of
chlorine; he discovered two new compounds of chlorine and
carbon:
hexachloroethane which he made via the chlorination of
ethylene and
carbon tetrachloride from the decomposition of the former. He also conducted the first rough experiments on the diffusion of gases, a phenomenon that was first pointed out by
John Dalton. The physical importance of this phenomenon was more fully revealed by
Thomas Graham and
Joseph Loschmidt. Faraday succeeded in liquefying several gases, investigated the alloys of steel, and produced several new kinds of glass intended for optical purposes. A specimen of one of these heavy glasses subsequently became historically important; when the glass was placed in a magnetic field Faraday determined the rotation of the plane of polarisation of light. This specimen was also the first substance found to be repelled by the poles of a magnet. Faraday invented an early form of what was to become the
Bunsen burner, which is still in practical use in science laboratories around the world as a convenient source of heat. Faraday worked extensively in the field of chemistry, discovering chemical substances such as
benzene (which he called bicarburet of hydrogen) and liquefying gases such as chlorine. The liquefying of gases helped to establish that gases are the vapours of liquids possessing a very low boiling point and gave a more solid basis to the concept of molecular aggregation. In 1820 Faraday reported the first synthesis of compounds made from carbon and chlorine,
C2Cl6 and
CCl4, and published his results the following year. Faraday also determined the composition of the chlorine
clathrate hydrate, which had been discovered by Humphry Davy in 1810. Faraday is also responsible for discovering the
laws of electrolysis, and for popularising terminology such as
anode,
cathode,
electrode, and
ion, terms proposed in large part by
William Whewell. Faraday was the first to report what later came to be called metallic
nanoparticles. In 1857 he discovered that the optical properties of gold
colloids differed from those of the corresponding bulk metal. This was probably the first reported observation of the effects of
quantum size, and might be considered to be the birth of
nanoscience.
Electricity and magnetism Faraday is best known for his work on electricity and magnetism. His first recorded experiment was the construction of a
voltaic pile with seven
British halfpenny coins, stacked together with seven discs of sheet zinc, and six pieces of paper moistened with salt water. In 1821, soon after the Danish physicist and chemist
Hans Christian Ørsted discovered the phenomenon of
electromagnetism, Davy and
William Hyde Wollaston tried, but failed, to design an
electric motor. From his initial discovery in 1821, Faraday continued his laboratory work, exploring electromagnetic properties of materials and developing requisite experience. In 1824, Faraday briefly set up a circuit to study whether a magnetic field could regulate the flow of a current in an adjacent wire, but he found no such relationship. This experiment followed similar work conducted with light and magnets three years earlier that yielded identical results. During the next seven years, Faraday spent much of his time perfecting his recipe for optical quality (heavy) glass, borosilicate of lead, which he used in his future studies connecting light with magnetism. In his spare time, Faraday continued publishing his experimental work on optics and electromagnetism; he conducted correspondence with scientists whom he had met on his journeys across Europe with Davy, and who were also working on electromagnetism. Two years after the death of Davy, in 1831, he began his great series of experiments in which he discovered
electromagnetic induction, recording in his laboratory diary on 28 October 1831 that he was "making many experiments with the great magnet of the Royal Society". was the first
electric generator. The horseshoe-shaped magnet
(A) created a magnetic field through the disc
(D). When the disc was turned, this induced an electric current radially outward from the centre toward the rim. The current flowed out through the sliding spring contact
m, through the external circuit, and back into the centre of the disc through the axle. Faraday's breakthrough came when he wrapped two insulated coils of wire around an iron ring, and found that, upon passing a current through one coil, a momentary current was induced in the other coil. The iron ring-coil apparatus is still on display at the Royal Institution. In subsequent experiments, he found that if he moved a magnet through a loop of wire an electric current flowed in that wire. The current also flowed if the loop was moved over a stationary magnet. His demonstrations established that a changing magnetic field produces an electric field; this relation was modelled mathematically by
James Clerk Maxwell as
Faraday's law, which subsequently became one of the four
Maxwell equations, and which have in turn evolved into the generalization known today as
field theory. (left), founders of electrochemistry In 1832, he completed a series of experiments aimed at investigating the fundamental nature of electricity; Faraday used "
static",
batteries, and "
animal electricity" to produce the phenomena of electrostatic attraction,
electrolysis,
magnetism, etc. He concluded that, contrary to the scientific opinion of the time, the divisions between the various "kinds" of electricity were illusory. Faraday instead proposed that only a single "electricity" exists, and the changing values of quantity and intensity (current and voltage) would produce different groups of phenomena. This idea was rejected by his fellow scientists, and Faraday did not live to see the eventual acceptance of his proposition by the scientific community. It would be another half a century before electricity was used in technology, with the
West End's
Savoy Theatre, fitted with the
incandescent light bulb developed by Sir
Joseph Swan, the first public building in the world to be lit by electricity. As recorded by the
Royal Institution, "Faraday invented the generator in 1831 but it took nearly 50 years before all the technology, including Joseph Swan's incandescent filament light bulbs used here, came into common use".
Diamagnetism material In 1845, Faraday discovered that many materials exhibit a weak repulsion from a magnetic field: an effect he termed
diamagnetism. Faraday also discovered that the plane of
polarization of linearly polarised light can be rotated by the application of an external magnetic field aligned with the direction in which the light is moving. This is now termed the
Faraday effect. Later on in his life, in 1862, Faraday used a spectroscope to search for a different alteration of light, the change of spectral lines by an applied magnetic field. The equipment available to him was, however, insufficient for a definite determination of spectral change.
Pieter Zeeman later used an improved apparatus to study the same phenomenon, publishing his results in 1897 and receiving the 1902 Nobel Prize in Physics for his success. In both his 1897 paper and his Nobel acceptance speech, Zeeman made reference to Faraday's work.
Faraday cage In his work on static electricity,
Faraday's ice pail experiment demonstrated that the charge resided only on the exterior of a charged conductor, and exterior charge had no influence on anything enclosed within a conductor. This is because the exterior charges redistribute such that the interior fields emerging from them cancel one another. This shielding effect is used in what is now known as a
Faraday cage. In January 1836, Faraday had put a wooden frame, 12 ft square, on four glass supports and added paper walls and wire mesh. He then stepped inside and electrified it. When he stepped out of his electrified cage, Faraday had shown that electricity was a force, not an imponderable fluid as was believed at the time. ==Royal Institution and public service==