Polonium the Curies while they were investigating the cause of pitchblende radioactivity. Pitchblende, after removal of the radioactive elements uranium and thorium, was more radioactive than the uranium and thorium combined. This spurred the Curies to search for additional radioactive elements. They first separated out polonium from pitchblende in July 1898, and five months later, also isolated radium. German scientist Willy Marckwald successfully isolated 3 milligrams of polonium in 1902, though at the time he believed it was a new element, which he dubbed "radio-tellurium", and it was not until 1905 that it was demonstrated to be the same as polonium.
Discover: The World of Science Discover: The World of Science Discover: The World of Science is an American television show that ran between 1983 and 1990. Actor Peter Graves is the on-camera host and narrator of "Discover: The World of Science", a monthly, one-hour magazine-style television series which provides a human perspective on new developments in robots, science, technology, medicine, the environment, behavior and natural history. The series was typically broadcast on Wednesday evenings at 8 PM on PBS. The series, with early episodes being underwritten by Atari and later episodes being underwritten by GTE, was produced by Chedd-Angier Productions in association with Discover Magazine.