Ever since carbonated drinks were invented, people have had to accept whatever level of fizziness was supplied by the factory. Today’s invention attempts to allow consumers to control this according to their personal taste.
Each bottle would be full to the top -with no air gap. The contents of each bottle would be injected with the same quantity of carbon dioxide. A consumer could reduce the amount of fizz in the bottle, from the maximum, factory-gate level, by unscrewing the cap a small amount -as indicated by the relative movement of marks on the cap edge and the bottle neck.
This would be arranged to occur without breaking the seal, so that a fraction of the gas would come out of solution, in response to the low pressure region and in proportion to the amount of initial unscrewing. A region of carbon dioxide would quickly form above the liquid surface and in equilibrium with it.
Opening the bottle would then allow the excess gas to escape at once and enable drinking the custom-fizzy liquid in the usual way.