French chemist and physicist. Investigated the behavior of gases and improved techniques of analyzing organic compounds.
He discovered independently that a gas at constant pressure expands, for each degree of temperature, by a constant fraction of its volume.
Gay-Lussac's name is mostly associated with another law of gases, the law of combining volumes, which Gay-Lussac was the first to formulate. This law states that when gases combine chemically with one another at constant pressure and temperature, they do so in simple proportions by volume and that the volume of the gaseous product formed bears a simple ratio to that of its constituents.
In 'De Magnete' he was the first to describe the earth's magnetic field and to postulate the relationship between electricity and magnetism. He introduced the term 'electricity' into scientific discourse. The 'gilbert', a unit equal to one centimeter-gram-second of magnetomotive force, is named for him.
In a famous experiment he placed two copper bowls of 14 inches diameter together to form a hollow sphere. After he removed the air from the sphere, horses were unable to pull the bowls apart, even tough they were held together only by air around them.
In 1663 Guericke invented the first electric generator, which produced electricity by applying friction against a revolving ball pof sulphur.
Hahn worked at first in London where he discovered a new radioactive substance, named radiothorium. He also worked under Ernest Rutherford at Montreal.
On his return to Europe Hahn moved to Berlin, where a thirty years' collaboration with Dr. Lise Meitner began. Following the discovery of artificial radioactivity by M and Mme. Joliot-Curie and the use of neutrons by Fermi for atomic nuclear processes, he bombarded uranium with neutrons. He suggested that bombarded 'uranium' was in fact barium, which led to Lise Meitner's conclusion that the nucleus had been split.
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