text: Paul-Émile Lecoq de Boisbaudran, also called François Lecoq de Boisbaudran (18 April 1838 – 28 May 1912), was a French chemist known for his discoveries of the chemical elements gallium, samarium and dysprosium. He developed methods for separation and purification of the rare earth elements and was one of the pioneers of the science of spectroscopy.