Radium emanator. This equipment was used in the household to produce water tainted with radioactive radon gas produced from a piece of radium ore inside the emanator. In the early 20th century it was thought that radon water was the ultimate health cure. This notion stemmed from the discovery that many of the natural hot springs that were used as health spas were radioactive. Entrepreneurs noticed this and started bottling and selling the spring water as radon water. They later designed ways, such as this equipment, for drinkers to produce their own radon water in the home.