‎"LECOQ de BOISBAUDRAN, PAUL ÈMILE. - RARE EARTH DISCOVERY - HOLMIUM AND DYSPROSIUM.‎
‎L'holmine (ou terre X de M. Soret) contient au moins deux radicaux métalliques. (+) Sur le dysprosium. (2 Papers).‎

‎(Paris, Gauthier-Villars), 1886. 4to. No wrappers. In: ""Comptes Rendus hebdomadaires des Séances de L'Academie des Sciences"", Tome 102, No 18. Pp. (991-) 1041. (Entire issue offered). The papers: pp. 1003-1004 a. 1005-1006.‎

Reference : 48205

‎First apperance of the papers in which Lecoc de Boisbaudran described how he separated Holmium into two kinds of earths and naming them.""He accomplished this by fractional prepicitation, first with ammonium hydroxide and then with a saturated solution of potassium sulfate, and found that the constituents of pure holmium solutions precipitate in the folloeing order: terbium, dysprosium, holmium, and erbium. Lecog de Boisbaudran never had an abundant supply of raw materials for his remarkable researches on the rare earths, and he once confided to professor Urbain that most of his fractionations had been carried on on the marble slab of his fireplace.""(Weeks ""Discovery of the Eelements"").Parkinson ""Breakthroughs"", 1886 C.‎