Marie Curie Read Online Free PDF

the relative power of the uranium.
    Now that she’d measured the amount of radiation given off by uranium, the next question was: did other elements besides uranium emit these strange rays? The only way to find out was to examine all the known elements. very persuasive when she needed something for her work, she begged and borrowed samples of elements from other scientists, including some of her old professors. She now went through Mendeleyev’s periodic table of elements, testing them one by one. The mystery rays weren’t just peculiar to uranium—she discovered that they came in a weaker form from thorium (a mineral element discovered in 1828) as well. Her findings were that only the elements uranium and thorium gave off this radiation.
    In April of 1898, Marie made a report to the all-important French Academy of Sciences. The eminent men at the meeting listened to a report on frog larvae. Then Marie’s report, called “Rays Emitted by Uranium and Thorium Compounds,” was read aloud by one of her professors. She couldn’t read it herself because she wasn’t a member—no women were allowed. Then came a report on hydraulics. . . .
    Marie returned to the lab and kept experimenting. Now that she had tested all the elements for Becquerel rays, she turned her attention to compound minerals, ones containing some uranium and thorium.
    She tested ores just as she had tested each element. Her interest was piqued in particular by a heavy black ore called pitchblende. Pitchblende contains a huge variety of minerals, including uranium and thorium. What she discovered was intriguing: pitchblende gave off four to five times more rays than could have been predicted by the amount of uranium and thorium in it.
    Why?
    Her leap in thinking was straightforward and brilliant at the same time.
    She came up with a hypothesis, a possible explanation that could be tested. A new element, considerably more active than uranium, must be present in the ore. She set out to look for an unknown substance of unusually high activity. “The element is there and I’ve got to find it,” she told Bronia. She was doing something completely new, looking for an unknown element with the only clue to its existence being its strange rays—rays that she called radioactive, meaning active in emitting rays.
    To Marie, time was of the essence. “I had a passionate desire to verify this hypothesis as rapidly as possible,” she wrote. She was aware of other scientists working in this area already, though perhaps not as precisely and systematically as she was. G. C. Schmidt in Germany, for example, was investigating the activity of thorium. There was a race on—all terribly polite, but still . . . Marie was determined to be first.
    At this point, Pierre showed what a generous spirit he had: he could see his wife was on the verge of discovering something major. As brilliant as he was, Marie’s work was leading in a more important direction. For a man raised in the nineteenth century, when the second-place status of women—both intellectually and physically—was a given, Pierre did something extraordinary. He stopped his work on crystals and joined her. Marie, who had something of a notebook obsession, had all along been keeping rigorous records of her work. Now her meticulous handwriting was interspersed with his childlike scrawl.
    Isolating this theoretical new element involved a process of elimination. All other elements in the pitchblende had to be separated out chemically. After weeks of attacking and reattacking their supply of pitchblende with all the chemicals available to them, the Curies produced something they suspected was their new element.
    How could they prove it? Possibly by looking at the light pattern produced by the substance. during Newton’s famous 1666 experiments, he first worked with sunlight and a prism, proving that light contains all the colors. By Marie’s time, a whole science—spectroscopy—had developed. In spectroscopy,