Bertrand Price Undercutting: A Brief Classroom Demonstration
A carbonation cap is provided for use with a conventional screw top bottle having an externally threaded neck. The carbonation cap is correspondingly internally threaded and includes one or more resilient seals which collectively function as check valves, pressure relief valves, and flow seals to enable the fermentation and carbonation of beer without transferring the beer from the bottle in which it was brewed. The resilient seals also enable the carbonation of soft drinks, or beer, from an external source of pressurized carbon dioxide. All of the foregoing is accomplished without at any time exposing the beverage or its components to the deletorious effects of the oxygen in the atmosphere.