Category:Caesium

Cæ"si*um, n. Etym: [NL., from L. caesius bluish gray.] (Chem.)

Defn: A rare alkaline metal found in mineral water; -- so called from the two characteristic blue lines in its spectrum. It was the first element discovered by spectrum analysis, and is the most strongly basic and electro-positive substance known. Symbol Cs. Atomic weight 132.6.