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
United States Radium Corporation years, it opened facilities in Newark, Jersey City, and Orange. In August 1921, von Sochocky was forced from the presidency, and the company was renamed the United States Radium Corporation. In Orange, where radium was extracted from 1917 to 1926, the U.S. Radium facility processed half a ton of ore per day. The ore was obtained from "Undark mines" in Paradox Valley, Colorado and in Utah. A notable employee from 1921 to 1923 was Victor Francis Hess, who would later receive the Nobel Prize in Physics. The company's luminescent paint, marketed as Undark, was a mixture of radium and zinc