Manhattan Rare Book Company

FIRST EDITION, OFFPRINT, of Bohr's 1915 paper identifying conclusive experimental evidence for his model of the atom.

"The central assumption [in the Bohr model] that 'stationary electron orbits' exist in atoms (and molecules) received justification in the crucial experiments of James Frank (1882-1964) and Gustav Hertz (1878-1975) in Berlin" although at the time the authors misinterpreted their results. They noted that "electrons in mercury vapor undergo elastic collisions with the molecules until they obtain a critical velocity, [and this] velocity is equivalent to the one obtained by electrons that have gone through a potential of 4.9 volts…

"Though the authors claimed until 1916 that the 4.9 V represented the ionization potential of mercury, [in the paper being offered] Bohr argued rather: 'It seems that their experiments may possibly be consistent with the assumption that this voltage corresponds only to the transition from the normal state to some stationary state of the neutral atom' [On the Quantum Theory of Radiation and the Structure of the Atom, 410-11]. Hence he considered the Frank-Hertz experiment to give strong support to his atomic theory, and the experimentalists finally agreed with him. A decade later they received the Nobel Prize for physics 'for their discovery of the law governing the impact of an electron upon an atom' and in particular for their verification of Bohr's hypothesis of stationary states and the frequency condition" (Brown, Pais, et al. Twentieth Century Physics).

With ownership signature on front wrapper of Harold S. King. King was a chemist who studied and worked at Harvard and later taught at Dalhousie University, Nova Scotia. He was the son of E.S. King, a noted Harvard astronomer.

Offprint from: The Philosophical Magazine, vol xxx, September 1915, pp. 394-415. London: Taylor and Francis, 1915. Octavo, original wrappers; custom cloth box. Extremely fragile wrappers with wear to spine with wrappers barely holding; text fine.

Price: $2,300 .