Barium: Barium Oxide Heated with Aluminium at 1200 °C in Vacuum (Guntz, Thorpe 1912)

Aluminium pulls the oxygen from barium oxide at 1200 °C. In a vacuum the freed barium boils off and condenses as metal in the cool end of the tube. Result: silver-white barium, up to 98.8 % pure. It burns easily in air; Thorpe keeps barium in dry carbon dioxide. Source: Thorpe, Dictionary of Applied Chemistry vol. 1 (1912), p. 418, after Guntz. Not given: the tube, amounts and time. Picture drawn by Youblob.