BECQUEREL, the name of a French family, several members of which have been distinguished in chemical and physical research.
Antoine Cesar Becquerel (1788-1878), was born at Chatillon sur Loing on the 8th of March 1788.
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 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 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.
Antoine Henri Becquerel (1852-1908), son of the lastnamed, who succeeded to his chair at the Musee 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 posts et chaussees, of which in 1894 he became chef.
Becquerel, by D.
Becquerel and by M.
Becquerel, however, investigated the character of the dispersion by using prism-shaped flames strongly coloured with sodium.
5, which was the effect noticed by Becquerel with the sodium flame.
After the discovery of the radioactive properties of uranium by Henri Becquerel in 1896, it was noticed that some minerals of uranium, such as pitchblende, were more active than the element itself, and this circumstance suggested that such minerals contained small quantities of some unknown substance or substances possessing radioactive properties in a very high degree.
Been made use of by Becquerel in his investigations of infra-red radiations.
Like the X rays, the Becquerel rays are invisible; they both traverse thin sheets of glass or metal, and cannot be refracted; moreover, they both ionize gases, i.e.
The Becquerel rays have a marked chemical action on certain substances.
C. Becquerel (1788-1878), G.
Becquerel in 1896 that minerals containing uranium, and particularly the mineral known as pitchblende, had the power of affecting sensitive photographic plates enclosed in a black paper envelope when the mineral was placed on the outside, as 1 See J.
(Avenarius, 1863.) (General type.) (Becquerel, 1863.) (Tait, 1870.) (Barus, 1889.) (Holborn and Wien, 1892.) (Paschen, 3893.) (Steele, 1894.) (Holman, 3896.) (Stanfield, 1898.) (Holborn and Day, 1899.) See sec. 15.) For moderate ranges of temperature the binomial formula of M.
Becquerel that the intensity of the effect depended on the thermoelectric power of the junction and was independent of its form or dimensions.
The infra-red requires special appliances; it has been examined visually by the help of phosphorescent plates (Becquerel), and with special photographic plates (Abney); but the most efficient way is to use the bolometer or radiomicrometer; by this means some 500 or 600 lines have been mapped.
Silver melts at about rooo C.; recent determinations give 960.7° (Heycock and Neville) and 962° (Becquerel); at higher temperatures it volatilizes with the formation of a pale blue vapour (Stas).
C. Becquerel, that plants possess no proper temperature, but are wholly dependent on that of the surrounding medium.