12 l respectively and a peripheral surface 12 s generally orthogonal to faces 12 u 12 l surface 12 s is circumscribed by a double o ring assembly 14 having upper and lower o rings 14 u 14 l respectively which are closely received within the open mouth 16 of a generally cylindrical container 18 filled to a preselected level with a quantity of wine 20 having an upper surface 20 s and are in slidable contact with the interior surface 18 s of the container container 18 has a bottom 18 b with an outlet 22 piston 12 has therethrough an air valve 24 having an upper end 24 u and a lower end 24 l which terminates proximate to face 12 l a rod 26 with a generally circular cross section of a preselected diameter and having upper and lower ends 26 u 26 l respectively is attached at end 26 l to face 12 u so that the centers of the rod end and face are generally congruent rod 26 is closely received by and passes through generally circular bore 28 h of a generally cylindrical weight 28 so that the weight rests on face 12 u preferably valve 24 is disposed sufficiently close to the periphery of piston 12 that there is sufficient clearance between the valve and weight to allow the weight to move down the rod onto the piston without interference after container 18 is filled with wine to a preselected level weight 28 exerts a gravitational force on piston 12 causing the piston to move downward until face 12 l contacts surface 20 s air compressed by the downward motion of the piston is expelled through valve 24 as the wine ages and ullage.