Cesium is named from the Latin caesius, sky blue and was discovered in 1860. Cesium, an alkali metal, occurs in lepidolite, pollucite (a hydrated silicate of aluminum and cesium) and in other sources. One of the world's richest sources of cesium is located at Bernic Lake, Manitoba. It can be isolated by electrolysis of the fused cyanide and by a number of other methods. Cesium is a silvery-white, soft and ductile metal that is the most electropositive and alkaline element. Cesium is only one of three metals that is liquid at room temperature. Because of its affinity for oxygen, the metal has been used as a "getter" in electron tubes. It is also used in photoelectric cells, as well as a catalyst in the hydrogenation of certian organic compounds. Cesium is used in atomic clocks which are accurate to 5 seconds in 300 years.