The invention relates to a method for removing gas, especially air, from flotation foam which is e.g. produced during deinking of a waste paper suspension. For degassing, e.g. a rotationally symmetrical chamber (5) is used inside which a rotor (3) is arranged and is adapted to set the inflowing flotation foam (1) rotating and to attach it to the inner wall (2) of the chamber (5) in the form of a rotating liquid ring (13). The degassed flotation foam (1') is removed through an outlet (8) in the inner wall (1), in the bottom (6) or in the upper wall (7) of the chamber (5). The removed gas can gather radially inside the liquid ring (13) and can be withdrawn.