Effervescence \Ef`fer*ves"cence\, Effervescency
\Ef`fer*ves"cen*cy\, n. [Cf. F. effervescence.]
A kind of natural ebullition; that commotion of a fluid which
takes place when some part of the mass flies off in a gaseous
form, producing innumerable small bubbles; as, the
effervescence of a carbonate with citric acid.
[1913 Webster]