BECQUEREL Henri (1852-1908) - Lot 128

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Lot n° 128
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BECQUEREL Henri (1852-1908) - Lot 128
BECQUEREL Henri (1852-1908) Autograph MANUSCRIT, [On electrons, 1907]; 14 pages and a quarter in-fol. (6 small cuts); in black cloth slipcase. Important study on electrons, radioactivity and molecular theories. This study was published in 1907 in the n° 65 of the Bulletin de la Société internationale des Électriciens. The manuscript, in black ink on the front of sheets of lined paper, shows erasures and corrections. It was accompanied in the margins by 6 diagrams or sketches that were cut out to be clichéd. It was used for printing in the journal. Becquerel begins by thanking his colleagues for having chosen him as President. Then he comes to the electrons. "The conception of electrons, after having been imposed by the observation of electric discharges in rarefied gases, has been wonderfully adapted to the interpretation of a great number of phenomena. I will quote in particular all the electro-optical phenomena, the manifestations of the radiation of the radioactive bodies, and the electric conductivity". He will then discuss "some of the principal experimental determinations that have made it possible to assign numerical values to the quantities that derive from this hypothesis". Cathode rays. Starting from the intuition of W. CROOKES, he describes the methods for deriving the values e/m, v and m/e (v) for cathode rays, Lenard rays, ultraviolet light and incandescent metals. The results are summarized in a table pasted at the bottom of p. 2 giving the numerical amounts, as well as the names of those responsible for their derivation (J.J. Thomson, Lenard, Kaufmann, Simon, Wiechert), the dates of derivation and the methods used. Channel rays. "In 1886 M. GOLDSTEIN recognized that in a rarefied gas tube, separated in two by a cathode pierced with holes, while on the anode side cathode rays are observed, on the other side through the small channels of the cathode, rays pass which are not very deflectable by an intense magnetic field, but which are deflected in the opposite direction to the cathode rays, and which can be considered as carrying positive electric charges. Becquerel applies himself to measure the charge e... Radiation of radioactive bodies. "The study of the spontaneous radiation of radioactive bodies has contributed greatly to our knowledge of the properties of electrons. Let us first recall that radioactive bodies emit energy in three forms: 1° a very small quantity of heat; 2° an emanation of a gaseous nature, the deposition of which causes temporary radioactivity on the bodies; 3° a radiation composed of three parts: a stream of positively charged atoms or α-rays identical to the channel rays, a stream of negatively charged electrons or βs rays identical to the cathode ray, and a very penetrating radiation or γ-rays assimilable to the X-rays. Becquerel discusses each of these rays in turn. He also discusses the identity of energy and mass in the context of determining the mass of the electron. The subsections on alpha and gamma rays are shorter, referring to the work of Rutherford, Bragg and Kleeman. Electro-optical phenomena. This section, the longest, contains a detailed discussion of the ZEEMAN effect and LORENTZ's theory: "M. Zeeman has discovered that the periods of the light motions emitted by an incandescent source are modified when this source is placed in a magnetic field. According to the theory of Mr. Lorentz, which inspired the experiment, the vibrations propagating in the direction of the field must be transformed into two circularly polarized vibrations in opposite directions, some a little slower, others a little faster than the corresponding primitive vibration, so that a line must be transformed into a doublet, when light is received in the direction of the magnetic field. [M. Lorentz admits that the luminous vibrations are the result of vibrations transmitted to the ether by electromagnetic phenomena that accompany the periodic movement of electrons. Becquerel also discusses the relationship between the Zeeman effect and the phenomenon of rotating magnetic polarization discovered by FARADAY, which allows the determination of e/m for a body at ordinary temperatures. He accompanies his remarks with calculations and a table. And he concludes: "We see that if the ratio e/m is of the same order of magnitude when it is deduced from the interpretation of very diverse phenomena, it is not possible to consider this ratio as constant. The invariability attributed to the elementary charge of electricity, implies variations in the real or apparent mass of electrons. For β-rays we can attribute these variations to the velocities of the electrons, but we have no similar information for the electrons of light sources or absorbing crystals. These would have
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