Henri Becquerel first try

Becquerel, at first, tried to induce fluorescence in some compounds by exposing them to sunlight. His results were misleading and inconsistent. Uranium was one of these compounds . He grew frustrated when Februaury came around, and there was hardly sunlight, and put the compounds in a drawer with the film he was using to measure the fluorescence. He developed, by chance, the film trays four days later. An outline of the uranium was shown. In the weeks that followed, Henri found, by performing vigorous experiments, that the fluorescence was a property of the Uranium itself rather than a product of the sun's influence.