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 dials could pick up readings from pants returned from a dry cleaner and from clothes stored away in a cedar chest." Although old radium dials may no longer produce light, this is frequently due to the breakdown of the crystal structure of zinc sulfide rather than the radioactive decay of the radium, which has a half-life of about 1600 years, so even very old radium dials remain radioactive. Radium paint can be ingested by inhaling flaking paint particles. The alpha particles emitted by the radium, which is taken up in bone, will kill off surrounding bone tissue, resulting in a condition