A process that was once used for producing oxygen through the heating of barium oxide in air to form barium peroxide. This was then heated to temperatures in excess of 800°C to produce oxygen:
The reaction was discovered by the French chemists Joseph-Louis Gay-Lussac (1778–1850) and Louis-Jacques Thénard (1777–1857). The process was particularly inefficient, and a major improvement was developed by Arthur and Leon Brin who found a way of removing the carbon dioxide with sodium hydroxide. The oxygen produced was used for limelight before more cost-effective methods of producing oxygen were discovered.