An improved closure for a bottle containing a gas-emitting solution. The closure is screwed onto the bottle and includes a disk member having a centrally disposed opening. The opening is sealed with a rupturable seal member. Two concentric, cylindrical members are disposed about the opening. A ballon-like member is fixedly secured to the open end of the cylindrical member next adjacent the opening so that when the gas emitting from the solution ruptures the seal member, the balloon is inflated to indicate excessive pressure.