Abstract: A valve (18) is disclosed for venting a liquid dispensing container. The valve comprises a valve body upper end (76), an intermediate portion (78) adapted to mourn through a sidewall aperture, and a semi-spherical lower end portion (80). An air passageway (96) extends into the valve upper end (76), and through the portion (78) to the lower portion (80). A slit opening (94) extends through the lower portion (80) and communicates with the passageway (96). The slit widens to equalize pressure in the container, and annular shoulder surfaces (92) and internal surfaces (62) of the container sidewall are compressed together. When equalization in pressure has been achieved, the lower valve portion (80) decompresses and resumes its normal configuration whereby causing the slit (94) to close. Surfaces (92, 62) have a complimentary downward angle to facilitate the return of the lower portion (80) into its semi-spherical shape.