BECQUEREL Henri (1852-1908) - Lot 127

Lot 127
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BECQUEREL Henri (1852-1908) - Lot 127
BECQUEREL Henri (1852-1908) MANUSCRIT autograph signed "Henri Becquerel", Spectres d'émission infra-rouges des vapeurs métalliques, [1884]; 4 pages and a quarter in-fol. in black cloth slipcase with title piece on the back. Working manuscript of his study of infrared radiation from metals. Draft and cleanup of the study published under this title in volume 99 of the Comptes-rendus de l'Académie des Sciences, 1884, pp. 374-376. Written in black ink on lined paper, they present numerous erasures and corrections. Becquerel states that he is continuing his "first research on the infrared emission spectra of metallic vapors unknown until then [...] by means of a special spectroscope [...] the principle of the method consists in projecting the spectra to be studied on a suitably chosen phosphorescent substance, previously made luminous, and in observing the temporary excitation which precedes the extinction under the influence of infrared radiation. The active lines and bands of the emission spectra then appear bright and can be examined with a microscope. While testing various phosphorescent substances, in particular certain preparations of calcium sulfide, I encountered some that were much more sensitive than others to infrared radiation. These substances allowed me to determine directly the wavelengths of the brightest lines of certain incandescent metallic vapors, Potassium, Sodium, Cadmium, by projecting the diffraction spectra provided by a very beautiful grating on metal by Mr. Rutherford [....] For other metals the spectra were obtained by means of a carbon sulfide prism. The positions of the lines were related to those of the Potassium and Sodium lines, and to the positions of the characteristic bands and lines of the infrared region of the solar spectrum, as well as to the absorption bands of Samarium; the wavelength of each line was then determined by interpolation with a fairly high degree of accuracy"... Etc. A table gives and comments the "Wavelengths in millionths of a millimeter" of potassium, sodium, strontium, calcium, magnesium, aluminum, zinc, cadmium, lead, bismuth, silver, tin... And Becquerel concludes: "Besides the interest that there may be in pointing out in the spectra of metallic vapors the existence of these radiations, whose wavelengths are considerable, this study, more than any other, is of a nature to give us the most precious information on the still unknown laws that govern the vibratory movements of incandescent vapors". A large pencil diagram of wavelengths of metallic vapors is attached. PROVENANCE The Harvey Plotnick Library of Quantum Physics (sale New York October 4, 2002, n° 6).
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