ABSTRACT
The X-rays had been discovered by Professor Rontgen of Wurzburg in the autumn of 1895, and early in 1896 Henri Becquerel, Professor of Physics in the Museum of Natural History in Paris, set to work to examine the radiations emitted by phosphorescent bodies of all kinds. In the expectation that the luminous rays might be accompanied by invisible but penetrating radiation, identical with or similar to the Rontgen rays. The radio-activity of a uranium compound is, however, tested more conveniently by the use of the electroscope, and it was by the systematic use of this instrument that Madame Curie, assisted by her husband, the late Professor Curie, was led to the discovery of radium. The discovery of helium in association with the minerals showing radio activity and from which radium was extracted, led Professors Rutherford and Soddy to suggest in 1902 that helium might be a product of the disintegration of the radio-elements.
