Radium of radium Curie used the residues after extraction of uranium from pitchblende. The uranium had been extracted by dissolution in sulfuric acid leaving radium sulfate, which is similar to barium sulfate but even less soluble in the residues. The residues also contained rather substantial amounts of barium sulfate which thus acted as a carrier for the radium sulfate. The first steps of the radium extraction process involved boiling with sodium hydroxide followed by hydrochloric acid treatment to remove as much as possible of other compounds. The remaining residue was then treated with sodium carbonate to convert the barium sulfate into
Radium to be primordial radionuclides and only exist in nature from these decay chains. Together with the artificial Ra (15 d), these are the five most stable isotopes of radium. All other known radium isotopes have half-lives under two hours, and the majority have half-lives under a minute. At least 12 nuclear isomers have been reported; the most stable of them is radium-205m, with a half-life of between 130 and 230 milliseconds, which is still shorter than twenty-four ground-state radium isotopes. In the early history of the study of radioactivity, the different natural isotopes of radium were given different names. In