Theory Decrease Velocity Moving Electrified by Bohr Niels, First Edition (2 results)

(22 x 14,5 cm). VIII, 824 S. Mit Abbildungen und 18 teils gefalteten Tafeln. Halbleinwandband der Zeit. Erste Ausgabe. - Bohr beschreibt hier die Kathodenstrahlexperimente von Franck und Hertz mit Hilfe seiner Theorie, besonders den Übergang vom Normalzustand des Atoms in einen anderen stationären Zustand. "Die berühmten Stoßexperimente von Franck und Hertz wurden von Bohr sofort als Bestätigung der Existenz diskreter Energieniveaus aufgefaßt" (Röseberg, Bohr). - Stempel auf Titel. Einband gering berieben, sonst sauber und gut erhalten. - DSB 2, 239; Röseberg, Bohr Nr. 16 und 17. - Der Band enthält weiter Arbeiten von J. J. Thomson, Rayleigh, Bragg, Rutherford, Soddy etc.

London, Taylor & Francis, 1913. 8vo. Original printed wrappers" chipped, backstrip lacks. The whole issue. 200 pp., 2 plates. First edition of Bohr's first work on nuclear physics, published just before his 'On the Constitution of Atoms and Molecules'. During his visit to Manchester Bohr had the chance to get a first hand account of Rutherford's investigations on the penetration of alpha-particles through matter. In order to explain the large-angle scattering of alpha rays, which Rutherford had observed, he proposed his "nuclear" model of the atom in contrast to J.J. Thomson's "plum pudding" model in 1910. Bohr eagerly took up the new model and soon recognized its far-reaching implications. In particular, he pointed out that the nuclear model of the atom implied a sharp separation between the chemical properties, ascribed to the peripherical electrons, and the radioactive properties, which affected the nucleas itself. In this paper the theory of the decrease of velocity of moving electrified particles in passing through matter is given in a form, such that the rate of the decrease in the velocity depends on the frequency of vibration of the electrons in the atoms of the absorbing material. In the conclusion Bohr could state 'that a hydrogen atom contains only 1 electron outside the positively charged nucleas, and that a helium atom only contains 2 electrons outside the nucleas'.Rosenfeld, Bohr Bibliography No. 5. Rosenfeld, Dictionary of Scientific Biography II, pp. 240-41.