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 Card card was used. A 1989 study found that Discover had strong consumer adoption in the U.S.; the number of households with Discover cards increased by 2.1 million, or 14 percent, in 1989. Discover was also noteworthy for being the only credit card accepted by the U.S. Customs Service to pay customs duty, effective Feb. 19, 1987. Since it did not charge a percentage fee to retailers, unlike Visa, MasterCard, and American Express, Discover was also the only credit card accepted at Sam's Club; the retailer has since started to accept MasterCard and American Express (see below). The plan to create