MENDELÉEFF, D. (MENDELÉEV, MENDELEYEV, MENDELÉEFF). - THE DECISIVE CONFIRMATION OF MENDELEEV'S PERIODIC TABLE OFTHE ELEMENTS.

Remarque à propos de la découverte du gallium.

Paris, Gauthier-Villars, 1875. 4to. No wrappers. In: "Comptes Rendus Hebdomadaires des Séances de L'Academie des Sciences", Tome 81, No 21. Pp. (909-) 992. With titlepage to vol. 81. Mendelejeff's paper: pp. 969-972. Titlepage lightly browned and with a punched stamp in lower margin. Otherwise clean and fine.

First apperance of this importent paper which established that Gallium is identical with Eka-aluminum (the missing element between Aluminum and Indium) in Mendelejeff's periodic table. The properties of the new element corresponded well with those predicted. A bitter contorversy was raised between the discoverer of Gallium, Lecog de Boisbaudran and Mendelejeff.

"The discovery of the three elements predicted by Mendeleev was, however, of decisive importance in the acceptance of his law. In 1875 Lecoq de Boisbaudran, knowing nothing of Mendeleev’s work, discovered by spectroscopic methods a new metal, which he named gallium. Both in the nature of its discovery and in a number of its properties gallium coincided with Mendeleev’s prediction for eka-aluminum, but its specific weight at first seemed to be less than predicted. Hearing of the discovery, Mendeleev sent to France "Zametka po povodu otkrytia gallia" (the paper offered) ("Note on the Occasion of the Discovery of Gallium"), in which he insisted that gallium was in fact his eka-aluminum. Although Lecoq de Boisbaudran objected to this interpretation, he made a second determination of the specific weight of gallium and confirmed that such was indeed the case. From that moment the periodic law was no longer a mere hypothesis, and the scientific world was astounded to note that Mendeleev, the theorist, had seen the properties of a new element more clearly than the chemist who had empirically discovered it. From this time, too, Mendeleev’s work came to be more widely known;"(DSB).

Parkinson "Breakthroughs" 1875 C.

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