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‎Die magnetische Ablenkbarkeit der Kathodestrahlen und ihre Abhängigkeit vom Entladungspotential.‎

‎Leipzig, Johann Ambrosius Barth, 1897. No wrappers. In: ""Annalen der Physik und Chemie, Neue Folge"", Bd. 61, No 7. Titlepager to vol. 61. Pp. 417-640 a. 1 folded plate. (Entire issue offered). Kaufmann's paper: pp. 544-552, textillustrations. A stamp to upper corner of titlepage. Clean and fine.‎

‎First printing of this landmark paper in particle physics, in which Kaufmann found that the cathode are negatively charged particles, that certain properties of the cathode rays are independent of the nature of the gas that they traverse, and determining the ratio e/m. (charge/mass)""To define the 'birth of an era' is perhaps best left for parlor games. Let me write of the BIRTH OF PARTICLE PHYSICS nevertheless, define it to take place in April 1897, and appoint Kaufmann and Thomson as keepers of the gate. Their respective experimental arrangements...are of comparable quality, their experimental results equally good.""(Pais ""Inward Bound"", p. 84.).""In 1897 three physicists, Weichert, Kaufmann, and Thomson, in independent experiments, found that cathode rays are indeed negatively charged particles having the peculiar property that the ratio of the mass and the charge of these particles is in the order of 1000 times smaller than for the lightest ion, the ion of the hydrogen. The term 'electron', which had previously been used to denote the 'elementary charge' , was soon adopted as the name of the new particle. The electron was the first of the later so-called 'elementary particles' to be discovered."" (Siegmund Brandt ""The Harvest of a Century"" No. 4 (p.16 ff.).‎