Codd style bottles are readily identified by their marble stopper.
The Codd bottle was filled upside down so that as soon the filling stopped,
the stopper was forced down to seal the bottle against the rubber ring.
Pressure inside the bottle would keep
the marble pressed against the top of the bottle.
To open the bottle, the marble was pressed down where it would fall
into the neck chamber below.
If the bottle is held the right way, the marble stays inside the chamber when
the bottle is tilted up for drinking.
Many of these bottles were destroyed when children would routinely break open
the bottle to get the marble inside.