Becquerel
In 1896, Becquerel's earlier work was surpassed by his discovery of the occurrence of natural radioactivity. Becquerel decided to investigate whether there was any connection between X-rays and naturally occurring phosphorescence, after his discussion with Henri Poincaré on the radiation which had been recently discovered by Röntgen (X-rays) and which was accompanied by a type of phosphorescence in the vacuum tube. He had inherited from his father a supply of uranium salts, which exhibits phosphorescence upon exposure to light. When the salts were placed near to a ph…