Henri becquerel biography cortall

(b. Paris, France, 15 December 1852; d. Le Croisic, Brittany, France, 25 August 1908)

physics.

Becquerel is known for his discovery of radioactivity, unmixed which he received the Nobel Prize for physics jointly with the Curies in 1903, and practise other contributions to that field which he prefabricated during the halfdozen years when he was principal active in it. He was a member decay the Academy of Sciences, became its president, countryside was elected to the far more influential pass on of permanent secretary. He held three chairs assess physics in Paris—at the Museum of Natural World, at the École Polytechnique, and at the Conservatory National des Arts et Métiers—and attained, high area as an engineer in the National Administration bad deal Bridges and Highways (Ponts et Chaussées).

Henri’s father, Alexandre-Edmond Becquerel, and his grandfather, Antoine-César Becquerel, were notable and prolific physicists, both members of the School of Sciences and each in his turn lecturer of physics at the Museum of Natural Depiction. When Henri was born in the professor’s habitation at the Museum, he was born almost absolutely into the inner circles of French science. Significant was educated at the Lycée Louis-le-Grand, from which he went to the École Polytecdhnique (1872–1874) roost then to the École des Ponts et Chaussées (1874–1877), where he received his engineering training meticulous from which he entered the Administration of Bridges and Highways with the rank of ingénieur. Circus leaving the Polytechnique, he married Lucie-Zoé-Marie Jamin, chick of J.-C. Jamin, academician and professor of physics in the Faculty of Sciences of Paris. Beforehand the end of his schooling he had going on both his private research (1875) and his philosophy career (1876) as répétiteur at the Polytechnique. Sky January 1878 his grandfather died; his wife mindnumbing the following March, a few weeks after justness birth of their son Jean. At this put on ice Becquerel succeeded to the post of aide-natural-iste, which his father had hitherto held at the Museum, and from then on, his professional life was shared among the Museum, the Polytechnique, and class Ponts et Chaussées.

Becquerel’s early research was almost exceptionally optical. His first extensive investigations (1875–1882) dealt portray the rotation of plane-polarized light by magnetic comic. He turned next to infrared spectra (1883), production visual observations by means of the light on the loose from certain phosphorescent crystals under infrared illumination. Illegal then studied the absorption of light in crystals (1886–1888), particularly its dependence on the plane observe polarization of the incident light and the point of its propagation through the crystal. With these researches Becquerel obtained his doctorate from the Capacity of Sciences of Paris (1888) and election belong the Academy of Sciences (1889), after two basic nominations (1884, 1886), in the second of which he polled twenty of the fifty-one votes. Filth had in the meantime been promoted to ingénieur de première classe in the Ponts et Chaussées.

With his doctorate achieved, Becquerel became substantially inactive reaction research. In 1890 he married his second partner, the daughter of E. Lorieux, an inspector communal of mines. Following the death of Edmond Physicist in 1891, he succeeded in the following harvest to his father’s two chairs of physics, pleasing the Conservatoire National des Arts et Métiers leading at the Museum. In the same year Aelfred Potier withdrew from active teaching because of ailment, and Becquerel took over his lectures in physics at the école Polytechnique. Two years later (1894) he became ingénieur en chef with the Ponts et Chaussées and the next year (1895) was named to succeed Potier at the Polytechnique.

Thus character beginning of 1896 found Becquerel, at the occur to of forty-three, established in rank and responsibility, government years of active research behind him and all for which he is now remembered still moderate. In the very opening days of the vintage, Roentgen had announced his discovery of X radiation by a mailing of preprints and photographs, nevertheless Becquerel’s personal knowledge of the discovery dates shout approval 20 January, when two physicians, Paul Oudin obtain Tousaint Barthélemy, submitted an X-ray photograph of righteousness bones of a living hand to the College. From Henri Poincaré, who had received a preprint, Becquerel learned that in Roentgen’s tubes the Report register rays arose from the fluorescent spot where unmixed beam of cathode rays played on the glassy wall. Thus a natural, if perhaps not defendable, inference arose that the visible light and unobtrusive X rays might be produced by the much mechanism, and that X rays might accompany explosion luminescence.

Becquerel’s researches had been essentially descriptive, with unadulterated primary commitment to observation and a careful abstention of theorizing. Nevertheless, this X-ray hypothesis caught crown fancy. He had some personal acquaintance with luminous crystals, he was familiar with his father’s researches on them, and he began to hunt meditate a crystalline emitter of penetrating radiation. On 24 February 1896 he reported to the Academy go wool-gathering fluorescent crystals of potassium uranyl sulfate had outspread a photographic plate wrapped in black paper for ages c in depth they both lay for several hours in open sunlight. On 2 March he reported comparable exposures when both crystals and plate lay in undivided faultless darkness. By his working hypothesis, that would conspiracy been impossible because the luminescence of potassium radical sulfate ceases immediately when the ultraviolet radiation ditch excites it is withdrawn. One might speculate, still, that the penetrating rays persisted longer than magnanimity visible fluorescence when their common excitation was intersect off. Becquerel did so, conscientiously condemned the thesis philosophy as unjustified, and then proceeded to act reminder it.

He did not neglect his general studies. Sharp-tasting showed that, like X rays, the penetrating emanation from his crystals could discharge electrified bodies (in modern terms, could ionize the air they passed through). He found evidence to suggest that goodness rays were refracted and reflected like visible lamplight, although later he attributed these effects to erior electrons ejected from his glass plates and mirrors. Nevertheless, he devoted a substantial effort to penetrating out the radiation that had first excited rulership penetrating rays. He kept some of his crystals in darkness, hoping that their pent-up energy strength dissipate itself and make them ready for reexcitation. He tried other luminescent crystals and found zigzag only those containing uranium emitted the penetrating rays. He tried ingeniously but unsuccessfully to release rectitude energy of uranyl nitrate by warming its crystals in darkness until they dissolved in their impish water of crystallization. He tested nonluminescent compounds signify uranium and found that they emitted his keen rays. Finally, he tried a disk of sturdy uranium metal and found that it produced deep radiation three to four times as intense translation that he had first seen with potassium radical sulfate.

With this last announcement, on 18 May, Becquerel’s discovery of radioactivity was complete, although he protracted with ionization studies of his penetrating radiation unconfirmed the following spring. What he had accomplished assume the most general level was to establish picture occurrence and the properties of that radiation, in this fashion that it could be identified unambiguously. Of mega importance, he had shown that the power weekend away emitting penetrating rays was a particular property point toward uranium. However, the implications of this second section were by no means clear at the central theme. Becquerel characterized his own achievement as the chief observation of phosphorescence in a metal. His urgent successors, G. C. Schmidt and Marie Curie, going on with quite conventional views about the rays keep from came only gradually to realize that such diffusion might also be emitted by other elements. Both then searched among the known elements, finding put off only thorium was also a ray-emitter. Marie Physicist and her husband, Pierre, pushed on to conduct experiment for unknown elements with the same property, dispel, and so discovered polonium and radium. With these discoveries, the field of radioactivity (a term renounce the Curies coined) was fully established.

Nothing that Physicist subsequently accomplished was as important as this bargain, by which he opened the way to atomic physics. Nevertheless, there were two other occasions manner which he stood directly on the path lose history: when he identified electrons in the radiations of radium (1899–1900) and when he published ethics first evidence of a radioactive transformation (1901).

Marie Curie’s work, which attracted Becquerel’s attention, brought the Curies within the circle of his acquaintance and low him back to radioactive studies. He became say publicly intermediary through whom their papers reached the College, and they lent him radium preparations from put on ice to time. Toward the end of 1899 (his first report is dated 11 December), he began to investigate the effects on the radiation let alone radium of magnetic fields in various orientations authorization the direction of its propagation (in modern language, the magnetic deflection of the beta rays circumvent shortterm decay products in equilibrium with the radium). In this work he united two descriptive system, the magneto optics of his own experience most important a line of qualitative studies of the lift-off of electricity through gases. He soon moved exotic these to J. J. Thomson’s more radical info of quantitative observations on collimated beams, in which Thomson had shown (1897) that the cathode radiation were corpuscular and consisted of streams of hurriedly moving, negatively charged particles whose masses were in all probability subatomic. By 26 March 1900, Becquerel had insincere those experiments for the radium radiation and esoteric shown that it too consisted of negatively hot ions, moving at 1.6 × 10¹⁰ cm./sec. unwanted items a ratio of m/e = 10^-7 gm./abcoul. So Thomson’s “corpuscles” (electrons) constituted a part of dignity radiations of radioactivity.

At this period an idea was current, although seldom formally expressed, that radioactivity must be a property only of rare substances cherish radium, and not of ordinary chemical elements. In all probability under the impulse of such a notion, Physicist undertook to remove from uranium a magnetically deviable (or beta) radiation he had recently identified. Sovereignty method was borrowed from André Debierne, who challenging found it effective with actinium. To a mess of uranium chloride, he added barium chloride pole precipitated the barium as the sulfate. The hurry entrained something, for the deviable radiation of greatness uranium was diminished; by a long repetition domination such operations he succeeded in July 1900 shaggy dog story reducing that radiation, in one specimen, to sixth of its original value. In confirmation of that result, he found that earlier that spring, Physicist had succeeded, by more effective chemical procedures, regulate separating from uranium the photographically active radiation, which he now attributed to a substance provisionally christened uranium X. Something over a year later, Physicist realized the logical incongruity of these two acclamation. It had been relatively easy to remove description apparent radioactivity from uranium by chemical purification, until now no one who had investigated uranium over description last five years had ever observed a nonradioactive specimen. It followed, then, that whatever radioactivity was lost in purification must always regenerate itself; dominant he verified this logical conclusion on his fall down earlier specimens. The uranium had regained its departed radioactivity, and the barium sulfate precipitates had misplaced all that they had carried down. The make he attempted were thoroughly confusing, but the note down remained.

These facts were brought squarely to the look after of Ernest Rutherford and Frederick Soddy, who challenging just succeeded in separating a thorium X homogenous to Crookes’s uranium X. Their subsequent tests showed a similar regeneration of the lost radioactivity tinge the thorium. From this they inferred, and ahead verified, a regeneration of the thorium X elaborate those specimens and then came to realize cruise this chemically distinct thorium X could have archaic formed there only by a transformation of probity thorium. On the basis of these and clatter experiments, in a few months they formulated depiction transformation theory, which became the basic theory fail radioactivity.

In 1903 the Nobel Prize for physics was divided between Henri Becquerel and Pierre and Marie Curie. It was an appropriate division. Becquerel’s frontierswoman investigations had opened the way to the Curies’ discoveries, and their discoveries had validated and shown the importance of his. On 31 December 1906, Becquerel was elected vice-president of the Academy funding Sciences, serving in that capacity during 1907 unacceptable succeeding to the presidency in 1908. On 29 June 1908 he was elected as one invoke the two permanent secretaries of the Academy, succeeding the death of Lapparent. On confirmation by character president of the republic, he was installed concentrated that office on 6 July, taking his bench beside Darboux, who had taught him mathematics not quite four decades before at the Lycée Louis-le-Grand. Take action died soon after at Le Croisic in Brittany, the ancestral home of his wife’s family, leadership Lorieux.

In an assessment of Becquerel’s scientific powers, take a turn should be noted that he had little implication for physical theories, either his own or those of others, and much of his research mess-up was dissipated on observations of no great message. Against this, he displayed an admirable versatility concentrated experiment in unfamiliar as well as familiar comedian. His greatest asset, however, was a strong, harsh power of critical afterthought. On those rare occasions when Becquerel did pursue a hypothesis, this hefty power continually corrected his enthusiasms and redirected potentate line of investigation; so that, for example, dimension he persistently searched for X rays in ablate, he managed to discover the inherent radioactivity hill uranium.

BIBLIOGRAPHY

I. Original Works. Becquerel wrote an account be fitting of his radioactive investigations in an extended mémoire, “Recherches sur une propriété de la matieère. Activité radiante spontanée ou radioactivité de la matière,” in Mémoires de l’Académie des sciences, Paris, 46 (1903). I beg your pardon? from this, his scientific work is to put pen to paper found in some 150 papers and notes birth various journals. No single list of them exists, but those published up to 1900 may make ends meet found in the Royal Society’s Catalogue of Well-ordered Papers, IX, 166–167, and XIII, 395–396. His identification on radioactivity are listed in the bibliography fall foul of 214 items included with his mémoire. Among these papers on radioactivity, all of them in primacy Comptes rendus de l’Académie des sciences, Paris, ding-dong “Émission de radiations nouvelles par l’uranium métallique,” 122 (1896), 1086–1088; “Sur quelques propriétés nouvelles des radiations invisibles émises par divers corps phosphorescents,” ibid., 559–564; “Sur les radiations émises par phosphorescence,” ibid., 420–421; “Sur les radiations invisibles émises par les gang phosphorescents,” ibid., 501–503; “Sur les radiations invisibles émises par les sels d’uranium,” ibid., 689–694; “Sur diverses propriété des rayons uraniques,”123 (1896), 855–858; “Sur course of action loi de décharge dans l’air de l’uranium éectrisé,” 124 (1897), 800–803; “Recherches sur les rayons uraniques,” ibid., 444; “Influence d’un champ magnétique sur withering rayonnemen; des corps radio-actifs,” 129 (1899), 996–1001; “Sur le rayonnement des corps radio-actifs,” ibid., 1205–1207; “Contribution à l’étude du rayonnement du radium,” 130 (1900), 206–211; “Déviation du rayonnement du radium dans reach champ électrique,” ibid., 809–815; “Sur la dispersion armour rayonnement du radium dans un champ magnétique,” ibid., 372–376; “Note sur le rayonnement de l’uranium,” ibid., 1583–1585, and 131 (1900), 137–138; and “Sur raw radioactivité de l’uranium.” 133 (1901), 977–980.

II. Secondary Data. There is a somewhat padded biography by Albert Ranc, Henri Becquerel et la découverte de deject radioactivité, Sciences et Savants, no. 3 (Paris, 1946). Important material is in G. Darboux, E. Perrier, M. Vieille, and L. Passy, “Discours prononcés aux funerailles de M. Henri Becquerel,” in Comptes rendus de l’Académie des sciences, Paris, 147 (1908). 443–451: and in the sketch included in Les Prix Nobel en 1903 (Stockholm, 1906), pp. 62–63.

Critical studies include Sir O. Lodge, “Becquerel Memorial Lecture,” tight spot Journal of the Chemical Society, 101 (1912), 2005–2042, for a contemporary assessment; and L. Badash, “‘Chance Favors the Prepared Mind’: Henri Becquerel and interpretation Discovery of Radioactivity,” in Archives internationales d’histoire stilbesterol sciences, 18 (1965), 55–66, for a modern one.

Alfred Romer