A raisin dropped in fresh champagne will keep bouncing up and down from the bottom to the top of the glass. When you add raisins to a glass of champagne, they’ll sink to the bottom at first. However, after some time, the raisins will move up and down in the glass dancing. This motion is due to dissolved carbon dioxide in the liquid. The CO2 bubbles cling to the surface of the raisins. Thus, the raisin method is used to “revive” flat champagne, as well.