![]() ![]() After noticing that the rays emitted by Radium could kill human tissue, Marie Curie developed the element into a new treatment for cancer. While Polonium, with its short half-life of 138 days, had no immediate commercial application, the discovery of Radium unleashed a scientific and cultural craze. Beyond having a couple duels fought over her in the interim as we’ve previously discussed, Marie Curie would come to be awarded the Nobel Prize in chemistry in 1911 for this feat, becoming the first and only woman to win not one but two Nobel prizes and the only person to win in two different scientific disciplines. After more than a decade of work in a leaky shack on the grounds of a Paris university, in which the Curies painstakingly processed literal tonnes of pitchblende, the pair finally managed to isolate two new radioactive elements: Radium, from the Latin for “ray,” and Polonium, after Marie Curie’s homeland of Poland. Other, even more radioactive elements, they concluded, must be lurking within the ore. The Curies’ continued investigations into radioactivity lead them to discover that the total radioactivity emitted by pitchblende, a common ore of Uranium, couldn’t be accounted for by the Uranium content alone. For these discoveries, the Curies and Becquerel would share the 1903 Nobel Prize in physics. But it would not be until 1898 that Polish-French scientist Marie Curie and her husband Pierre gave a name to this phenomenon: radioactivity. Soon similar rays were discovered emanating from other elements such as Thorium. Becquerel could only conclude that these rays had nothing to do with sunlight and phosphorescence and were a property inherent to the salts themselves. Further experiments confirmed the phenomenon: no matter how long the salts were left in darkness, they continued to emit their mysterious rays at the same intensity. When he returned the next day and developed the plate, to his surprise the exposed outlines still appeared in the emulsion – even though the Uranium salts had been stored in complete darkness. On February 29, 1896, finding the sky too overcast for his experiments, Becquerel placed a plate and salt samples in his desk drawer and left them there overnight. ![]() As expected, when he developed the plate, invisible rays emitted by the salts were recorded as perfect outlines on the emulsion. To test his hypothesis, Becquerel wrapped photographic plates in opaque black paper, placed samples of Uranium salt on top of them, and left them in the sun for several hours. Röntgen called them “X-rays,” “X” standing for “unknown.” A year later, French chemist Henri Becquerel began experimenting with salts of the element Uranium, suspecting that their fluorescent and phosphorescent properties were in some way related to Röntgen’s mysterious X-rays. In 1895 German physicist Wilhelm Röntgen was experimenting with an electrified gas-filled apparatus known as a Crookes tube when he discovered that the tube emitted invisible rays which could make fluorescent materials glow, develop photographic emulsion, and penetrate all kinds of materials – including human flesh. Uranium glass, also known as vaseline glass or Depression glass, was extremely popular during the 1930s and glows bright “radioactive” green under ultraviolet light.īut while none of these natural Uranium compounds emit light spontaneously or continuously, it was their unique fluorescent and phosphorescent properties which lead inadvertently to the discovery of radioactivity. Indeed, until the start of the Manhattan Project in the early 1940s, the main use of Uranium in industry was as a pigment for colouring ceramics and glass. Many natural ores of Uranium like Autunite and Saleeite are fluorescent and phosphorescent, meaning that they will glow brightly under ultraviolet light and continue to glow in the dark for some time after first being charged in sunlight. So then, how did the image of glowing green sludge come to dominate our collective perception of radioactivity? It is an image which has appeared in countless movies and TV shows, yet, as we saw in our previous video How Does Nuclear Waste Disposal Work, real nuclear waste looks nothing as exciting as its fictional counterpart, consisting mainly of rather plain-looking rods of depleted Uranium pulled from nuclear reactor cores. If I were to ask you to picture “radioactive waste,” the image that would likely spring to mind is that of a rusty metal barrel leaking glowing, neon-green sludge. ![]()
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