Radium seventh of a gram of radium. One kilogram of the Earth's crust contains about 900 picograms of radium, and one liter of sea water contains about 89 femtograms of radium. Radium was discovered by Marie Sklodowska-Curie and her husband Pierre Curie on 21 December 1898, in a uraninite (pitchblende) sample. While studying the mineral earlier, the Curies removed uranium from it and found that the remaining material was still radioactive. They separated out an element similar to bismuth from pitchblende in July 1898, that turned out to be polonium. They then separated out a radioactive mixture consisting mostly of two
Discover the Networks Discover the Networks Discover the Networks (originally Discover the Network) (DtN) is a website run by the David Horowitz Freedom Center that focuses on the individuals, groups, and history of groups alleged to be politically left wing. DtN was launched in 2004 and has a staff of about a dozen contributors. Its current Editor-in-Chief is David Horowitz; John Perazzo is the project's managing editor, and Richard Poe is its investigative editor. Discover the Networks is associated with FrontPageMag.com. According to the project's mission statement, DtN's goal is to provide a comprehensive "guide to the political left" covering "the individuals and