His early work included studies of phosphorescence and luminescence and the conductivity of flames. Some selenite and satin spar specimens exhibit fluorescence or phosphorescence. He is also known for his work in luminescence and phosphorescence. Calcite is transparent to opaque and may occasionally show phosphorescence or fluorescence. From them a faint bioluminescence (often called phosphorescence) occurs. The process then corresponds to one of two phenomena- delayed fluorescence or phosphorescence. In other words, it gives off visible light through fluorescence, phosphorescence, or radioluminescence. In chemistry-related disciplines, one often distinguishes between fluorescence and phosphorescence. This law provides a basis for fluorescence and phosphorescence. Most applications of europium exploit the phosphorescence of europium compounds. He published many articles on spectroscopy, phosphorescence, diffraction, and ultraviolet light. A light-emitting capacitor is made from a dielectric that uses phosphorescence to produce light. Natural phosphorescence give its eel-like skin an eerie glow. Some examples of glow-in-the-dark materials do not glow by phosphorescence. Almost invariably, its phosphorescence is exploited, either in the +2 or +3 oxidation state.