‎"BECQUEREL, HENRI.‎
‎Sur le rayonnement des corps radio-actifs. (Séance du Mardi 26 Décembre 1899).‎

‎(Paris, Gauthier-Villars), 1899. 4to. No wrappers. In: ""Comptes Rendus Hebdomadaires des Séances de L'Academie des Sciences"", Tome 129, No 26. Pp. (1201-) 1296. (Entire issue offered). Becquerel's paper: pp. 1205-1207. Clean and fine.‎

Reference : 49601

‎First printing of an early importent investigation on the newly (1896) discovered phenomenon of radioactivity.""Toward the end of 1899 (his first report is dated 11 December), he began to investigate the effects on the radiation from radium of magnetic fields in various orientations to the direction of its propagation (in modern terms, the magnetic deflection of the beta rays from shortterm decay products in equilibrium with the radium). In this work he united two descriptive traditions, the magneto optics of his own experience and a line of qualitative studies of the discharge of electricity through gases. He soon moved from these to J. J. Thomson’s more radical program of quantitative observations on collimated beams, in which Thomson had shown (1897) that the cathode rays were corpuscular and consisted of streams of swiftly moving, negatively charged particles whose masses were probably subatomic. By 26 March 1900, Becquerel had duplicated those experiments for the radium radiation and had shown that it too consisted of negatively charged ions, moving at 1.6 × 1010 cm./sec. with a ratio of m/e = 10-7 gm./abcoul. Thus Thomson’s ""corpuscles"" (electrons) constituted a part of the radiations of radioactivity."" (DSB).‎