Radium Chloride: Pitchblende Residues Worked Up and the Chlorides Fractionally Crystallised from Hydrochloric Acid (Curie, Debierne, Haitinger and Ulrich, Thorpe 1912)

Radium hides in the residue left when uranium is leached out of pitchblende, together with barium. Boiling with soda and acids frees it as a radium-barium sulphate, and endless crystallisation of the chlorides from ever stronger hydrochloric acid slowly concentrates the less soluble radium chloride. Result: radium chloride (a ton of residues gives 10-20 kg of crude barium-radium sulphate to start the crystallisations). Source: Thorpe, Dictionary of Applied Chemistry vol. 4 (1912), RADIUM, pp. 544-545. Radium is intensely radioactive and a poison; hydrogen sulphide is a deadly gas. Picture drawn by Youblob.