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 chloride Radium chloride Radium chloride (RaCl) is a chemical compound of radium and chlorine, and the first radium compound isolated in a pure state. Marie Curie and André-Louis Debierne used it in their original separation of radium from barium. The first preparation of radium metal was by the electrolysis of a solution of this salt using a mercury cathode. Radium chloride crystallises from solution as the dihydrate. It may be dehydrated by heating to 100 °C in air for one hour followed by hours at 520 °C under argon. If the presence of other anions is suspected, the dehydration may be