Pour out a glass of champagne, or bottled ale, and wait till the
effervescence has ceased; you may then renew it by throwing into the
liquor a bit of paper, a crumb of bread, or even by violently shaking
the glass. The bubbles of carbonic acid chiefly rise from where the
liquor is in contact with the glass, and is in greatest abundance at
those parts where there are asperities. The bubbles setting out from
the surface of the glass are at first very small; but they enlarge
in passing through the liquor. It seems as if they proceeded more
abundantly from the bottom of the glass than from its sides; but this
is an ocular deception.