Lecoq de Boisbaudran experimented with the precipitation of rare earth compounds from water solution using potassium sulfate to induce precipitation. He then measured the spectra of solutions in which the liquid served as a positive pole. Lecoq de Boisbaudran noted a  spectral band in the yellow-green portion of the spectrum, indicative of a new element. In 1886 he succeeded in isolating a purified sample of the source of the new spectral band.  He named the element dysprosium, meaning "difficult to obtain" in the Greek language.