Bohuslav Brauner
Brauner was a student of Robert Bunsen at the University of Heidelberg and later of Henry Roscoe at the University of Manchester. Brauner became lecturer for chemistry at the University of Prague in 1883 and professor in 1890. He worked on the chemistry of the lanthanides, and in 1902 proposed that an element was missing between neodymium and samarium it was later found to be promethium. Brauners conflict with Carl Auer von Welsbach about the priority for the discovery that didymium is a mixture of two elements was harsh. However, in the end Brauner withdrew his claims for unknown reasons.
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Source: Wikipedia