The idea is to pressurise the carbon dioxide so that it becomes a liquid. The fluid is then released into the dishwasher where it cleans the dishes all by itself.
Perhaps unsurprisingly, whenever one of these poor women was being tortured and pressurised to name other fellow witches, they would name dozens of people in an attempt to stop the pain.
Rather than simply situating a Moon base inside a lava tube—domes and shiny buildings and all—they suggested that a section of such a tube could be pressurised with breathable air.