Paris, Gauthier-Villars, 1896. 4to. No wrappers. In: ""Comptes Rendus Hebdomadaires des Séances de L'Academie des Sciences"", Tome 123,, No 21. Pp. (771-) 854. (Entire issue offered). Fabry and Perot's paper: pp. 802-805.
First printing of one of Becquerel's importent papers relating to his discovery of radioactivity this same year. Here he confirms that uranium salts emits some forms of radiation and these rays he names ""rayons uraniques"" (URANIUM RAYS)