Émile Henriot (2 July 1885–1 February 1961) was a French chemist notable for being the first to show definitively that

potassium Potassium is a chemical element; it has Symbol (chemistry), symbol K (from Neo-Latin ) and atomic number19. It is a silvery white metal that is soft enough to easily cut with a knife. Potassium metal reacts rapidly with atmospheric oxygen to ...

and

rubidium Rubidium is a chemical element; it has Symbol (chemistry), symbol Rb and atomic number 37. It is a very soft, whitish-grey solid in the alkali metal group, similar to potassium and caesium. Rubidium is the first alkali metal in the group to have ...

are naturally radioactive. He investigated methods to generate extremely high angular velocities, and found that suitably placed air-jets can be used to spin tops at very high speeds—this technique was later used to construct ultracentrifuges. He was a pioneer in the study of the

electron microscope An electron microscope is a microscope that uses a beam of electrons as a source of illumination. It uses electron optics that are analogous to the glass lenses of an optical light microscope to control the electron beam, for instance focusing it ...

. He also studied

birefringence Birefringence, also called double refraction, is the optical property of a material having a refractive index that depends on the polarization and propagation direction of light. These optically anisotropic materials are described as birefrin ...

and molecular vibrations. He obtained his DSc in physics in 1912 the Sorbonne,

Paris Paris () is the Capital city, capital and List of communes in France with over 20,000 inhabitants, largest city of France. With an estimated population of 2,048,472 residents in January 2025 in an area of more than , Paris is the List of ci ...

, under

Marie Curie Maria Salomea Skłodowska-Curie (; ; 7 November 1867 – 4 July 1934), known simply as Marie Curie ( ; ), was a Polish and naturalised-French physicist and chemist who conducted pioneering research on radioactivity. She was List of female ...

. As a professor at the Free University of Brussels he attended the Solvay Conferences of 1924, 1927, 1930, 1933, 1948, 1951 and 1954. For many of the conferences he assisted with preparing the venue or other administrative tasks.

References

* * ''Biographie Nationale publiée par L’Académie Royale des Sciences, des Lettres et des Beaux-Arts de Belgique'', Établissements Émile Bruylant: 1866-1986, vol. 12 (suppl.), col 421-423. * ''Acad. Roy. Belg. Ann.'', 1964, 130, pp. 47–59. * ''Acad. Roy. Sci. Bull. Cl. Sci.'', 1961, 47, p. 680. * ''Le Radium'', 1908, 5, pp. 41–46 *
Radioactivity in the Natural Environment
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a

b
Lawrence Berkeley National Laboratory

''Natural Radioactivity and Radiation''
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National Library of Medicine

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1885 births 1961 deaths University of Paris alumni 20th-century French chemists French military personnel of World War I {{france-chemist-stub