BECQUEREL, the name of a French family, several members of which have been distinguished in chemical and physical research.
Antoine César Becquerel (1788-1878), was born at Châtillon sur Loing on the 8th of March 1788. After passing through the Ecole Polytechnique he became ingénieur-officier in 1808, and saw active service with the imperial troops in Spain from 1810 to 1812, and again in France in 1814. He then resigned from the army and devoted the rest of his life to scientific investigation. His earliest work was mineralogical in character, but he soon turned his attention to the study of electricity and especially of electrochemistry. In 1837 he received the Copley medal from the Royal Society "for his various memoirs on electricity, and particularly for those on the production of metallic sulphurets and sulphur by the long-continued action of electricity of very low tension," which it was hoped would lead to increased knowledge of the "recomposition of crystallized bodies, and the processes which may have been employed by nature in the production of such bodies in the mineral kingdom." In biological chemistry he worked at the problems of animal heat and at the phenomena accompanying the growth of plants, and he also devoted much time to meteorological questions and observations. He was a prolific writer, his books including Traité d'électricité et du magnétisme (1834-1840), Traité de physique dans ses rapports avec la chimie (1842), Eléments de l'électro-chimie (1843), Traité complet du magnétisme (1845), Eléments de physique terrestre et de météorologie (1847), and Des climats et de l'influence qu'exercent les sols boisés et déboisés (1853). He died on the 18th of January 1878 in Paris, where from 1837 he had been professor of physics at the Musée d'Histoire Naturelle.
His son, Alexandre Edmond Becquerel (1820-1891), was born in Paris on the 24th of March 1820, and was in turn his pupil, assistant and successor at the Musée d'Histoire Naturelle; he was also appointed professor at the short-lived Agronomic Institute at Versailles in 1849, and in 1853 received the chair of physics at the Conservatoire des Arts et Métiers. Edmond Becquerel was associated with his father in much of his work, but he himself paid special attention to the study of light, investigating the photochemical effects and spectroscopic characters of solar radiation and the electric light, and the phenomena of phosphorescence, particularly as displayed by the sulphides and by compounds of uranium. It was in connexion with these latter inquiries that he devised his phosphoroscope, an apparatus which enabled the interval between exposure to the source of light and observation of the resulting effects to be varied at will and accurately measured. He published in 1867-1868 a treatise in two volumes on La Lumière, ses causes et ses effets. He also investigated the diamagnetic and paramagnetic properties of substances; and was keenly interested in the phenomena of electrochemical decomposition, accumulating much evidence in favour of Faraday's law and proposing a modified statement of it which was intended to cover certain apparent exceptions. He died in Paris on the 11th of May 1891.
Antoine Henri Becquerel (1852-1908), son of the last-named, who succeeded to his chair at the Musée d'Histoire Naturelle in 1892, was born in Paris on the 15th of December 1852, studied at the Ecole Polytechnique, where he was appointed a professor in 1895, and in 1875 entered the department des ponts et chaussées, of which in 1894 he became ingénieur en chef. He was distinguished as the discoverer of radioactivity, having found in 1896 that uranium at ordinary temperatures emits an invisible radiation which in many respects resembles Röntgen rays, and can affect a photographic plate after passing through thin plates of metal. For his researches in this department he was in 1903 awarded a Nobel prize jointly with Pierre Curie. He also engaged in work on magnetism, the polarization of light, phosphorescence and the absorption of light in crystals. He died at Croisic in Brittany on the 25th of August 1908.
Note - this article incorporates content from Encyclopaedia Britannica, Eleventh Edition, (1910-1911)