Antoine Cesar Becquerel

ANTOINE CESAR BECQUEREL (1788-1878) was born at Chatillon sur Loing on March 8, 1788. After passing through the h cole Polytechnique he became ingenieur-oficier in 1808, and saw active service with the imperial troops in Spain from 181 o to 1812, and again in France in 1814. He then resigned from the army. His earliest scientific work was in mineralogy, but he soon turned his attention to the study of electricity and especially of electro chemistry. 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 "recompo sition 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 studied meteorological questions and observations. His works include : Traite d'electricite et du ma gnetisme (1834-40), Traite de physique dans ses rapports avec la chimie (1842) , Elements de l'tilectro-chimie (1843), Traite cour plet du magnetisme (1845), Elements de physique terrestre et de meteorologie (1847), and Des climats et de l'influence qu'exercent les sols boises et deboises (1853). He died on Jan. 18, 1878, in Paris, where from 1837 he had been professor of physics at the Musee d'Histoire Naturelle.

His son,

ALEXANDRE EDMOND BECQUEREL (I 8 20-91), was born in Paris on March 24, 182o, and was in turn his pupil, assistant and successor at the Musee 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 Metiers. Edmond Becquerel paid special attention to the study of light, investigating the photo chemical 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. In connection with these latter inquiries 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 1867-68 a treatise in two volumes on La Lumiere, ses causes et ses e ff ets. He also investigated the diamagnetic and paramagnetic properties of substances and the phenomena of electrochemical decomposition ; and proposed a modified statement of Faraday's law which was intended to cover certain apparent exceptions. He died in Paris on May 11, 1891.

His son, ANTOINE HENRI BECQUEREL (1852-1908), who suc ceeded to his father's chair at the Musee d'Histoire Naturelle in 1892, was born in Paris on Dec. 15, 1852, studied at the 1?cole Polytechnique (where he was appointed a professor in 1895), and in 1875 entered the department des ponts et chaussees, of which in 1894 he became ingenieur en chef. He was the discoverer of radioactivity, having found in 1896 that uranium at ordinary temperatures emits an invisible radiation which in many respects resembles Rontgen rays, and can affect a photographic plate after passing through thin plates of metal. For these researches 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 Aug. 25, 1908.