emanation

(em-an-a’shun) [L. e out + mana’re to flow). 1. That which is given off; an effluvium. 2. A gaseous disintegration product given off from radio-active substances. radium-e., a condensable gas given off by radium and regarded as an element, having an atomic weight of 222.4. It forms the radio-active clement of radium and is used like the latter. Called also nifon.