Work at the Paris school
A portrait record dated 1898 in the Curie Museum identifies Bémont as a laboratory chief at the municipal school of industrial physics and chemistry in Paris. In Chapter V of Pierre Curie, Marie Curie recalled that he had given them temporary experimental help in 1898.
The paper announcing radium
The 1898 Comptes rendus paper On a new, strongly radioactive substance, contained in pitchblende bears the names of Pierre Curie, Marie Curie and Bémont. It described a highly radioactive, barium-like fraction and combined chemical separation with activity measurements and spectral evidence to propose a new element, radium. The authors explicitly noted that their material still contained much barium: the announcement was not a claim to have isolated pure radium metal.
References: [2]