Polonium in the Earth's crust are not harmful. Polonium has been found in tobacco smoke from tobacco leaves grown with phosphate fertilizers. Because it is present in small concentrations, isolation of polonium from natural sources is a tedious process. The largest batch of the element ever extracted, performed in the first half of the 20th century, contained only (9 mg) of polonium-210 and was obtained by processing 37 tonnes of residues from radium production. Polonium is now usually obtained by irradiating bismuth with high-energy neutrons or protons. In 1934, an experiment showed that when natural Bi is bombarded with neutrons, Bi
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.