Your salts were made by Hippolyte-Pierre Bompard, hollowware maker, working in Paris at 79 Quai de l’Horloge. His symbol was a plume with a star (un panache et une étoile). Bompard first registered his mark on 13 October 1834, erased 7 January 1851. As your object is stamped with the Minerva mark, it can be dated between 1838 and 1851.