An inert gaseous element of the argon group, occurring in air to the extent of about one volume in a million. It was discovered by Ramsay and Travers in 1898. Liquefying point, -- 152° C.; symbol, Kr; atomic weight, 83.0.
- A whitish, largely inert gaseous element used chiefly in gas discharge lamps and fluorescent lamps. Atomic number 36; atomic weight 83.80; melting point -156.6°C; boiling point -152.30°C; density 3.73 grams per liter (0°C). See Table at element.