Oxygen: Manganese Dioxide Heated to Bright Redness in an Iron Bottle

Oxygen from pyrolusite, as Thorpe's Dictionary (1913) gives it: heated to a bright-red heat, manganese dioxide gives up a third of its oxygen. Glass will not stand the heat, so it is heated in an iron bottle in a furnace. Pure dioxide yields 12.3 parts of oxygen per 100; pyrolusite, about 70 % dioxide, gives less. The picture: our diagram.