[From X-rays to radioactivity and radium. The discovery and works of Henri Becquerel (1851-1908)].

The discovery of radioactivity was the outcome of a methodical experimental study achieved by Becquerel. He continued his discovery with studies which give evidence of his scientific and experimentative mind. These studies explored the nature and properties of the emitted radiation and brought basic data to the disintegration theory. The twin discoveries of Röntgen and Becquerel opened new scientific areas, and their practical applications were unprecedented. They gave a new dimension to basic and applied research.