![]() Success came in 1902, when they announced they had isolated 0.1g of pure radium chloride, RaCl 2, from almost 3 tons of pitchblende. Marie and her husband Pierre named this mystery substance radium in 1898. In the same paper she reported that pitchblende, an ore consisting mainly of UO 2, was three times as active as uranium oxide, U 2O 5.Ĭorrectly supposing that some other, as yet unknown, species was responsible for this enhanced activity, Marie Curie spent the next four years isolating it from pitchblende. Her first success, in 1898, was finding that thorium, like uranium, was radioactive. She used an electrometer (an improvement on the electroscope, though both depend on the ability of the radiation to ionise air) to detect and quantify the radioactivity. Marie Curie, working at the Sorbonne, Paris, decided that Becquerel's radioactivity might prove a fruitful field for investigation. Source: National Library of Medicine/Science Photo Library There were similarities with Roentgen's x-rays, which could also blacken photographic film, and both could discharge an electroscope, indicating they caused ionisation of the air. Nevertheless, it was the world's first report of radioactivity. ![]() The effect, of course, was due to the uranium itself, rather than any phosphorescence. One must conclude from these experiments that the phosphorescent substance in question emits rays which pass through the opaque paper and reduces silver salts. If one places between the phosphorescent substance and the paper a piece of money or a metal screen pierced with a cut-out design, one sees the image of these objects appear on the negative. When one then develops the photographic plate, one recognizes that the silhouette of the phosphorescent substance appears in black on the negative. On developing the film he was surprised to find the film had been 'fogged'. Becquerel had left some potassium uranyl sulfate in contact with photographic film that was sealed in black paper to protect it from light. Although this was unsuccessful, by November that year x-rays were being used to cure superficial cancers, such as skin cancers, which were more accessible to the radiation.Ī month or two after Roentgen's discovery, Henri Becquerel was working on the phosphorescence of uranium salts. In January 1896, Chicago physician Emile Grubbe, having noted the destructive effect of the rays on his own skin, applied them in the hope of "burning out" a patient's breast cancer. Repeated exposure damaged their tissues, sometimes causing cancer. This last finding was discovered by chance as the early researchers were unaware of the energy of x-rays.
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