Lanthanum: Anhydrous Chloride Reduced with Calcium in a Tantalum Bomb under Argon, then Vacuum Cast (Daane, Ames 1950)

Oxide refractories put oxygen into rare-earth metals. Daane reduced dry lanthanum chloride with calcium inside a closed tantalum crucible under argon, so nothing but tantalum touched the melt, then boiled out the spare calcium in vacuum and cast the metal. Result: lanthanum metal, about 100 % yield (20 g from 33 g of chloride), with 150 ppm calcium. Source: A. H. Daane, The Vapor Pressures of Lanthanum and Praseodymium (Iowa State College / Ames Laboratory, 1950), pp. 26-44. Hydrogen chloride and strong hydrochloric acid are corrosive; work at 1400 °C in vacuum. Picture drawn by Youblob.