Marie Curie doubt, the Curies sought to isolate polonium and radium in pure form. Pitchblende is a complex mineral; the chemical separation of its constituents was an arduous task. The discovery of polonium had been relatively easy; chemically it resembles the element bismuth, and polonium was the only bismuth-like substance in the ore. Radium, however, was more elusive; it is closely related chemically to barium, and pitchblende contains both elements. By 1898 the Curies had obtained traces of radium, but appreciable quantities, uncontaminated with barium, were still beyond reach. The Curies undertook the arduous task of separating out radium salt by differential
Polonium materials from leaking out. Gloves made of natural rubber do not provide sufficient protection against the radiation from polonium; surgical gloves are necessary. Neoprene gloves shield radiation from polonium better than natural rubber. Polonium was administered to humans for experimental purposes from 1943 to 1947; it was injected into four hospitalised patients, and orally given to a fifth. Studies such as this were funded by the Manhattan Project and the AEC and conducted at the University of Rochester. The objective was to obtain data on human excretion of polonium to correlate with more extensive data from rats. Patients selected as