"Montclare"

For filling burets. Diameter: 35 mm; total length: 60 mm; outside diameter of stem: 6 mm.

A dramatic visualization of air pressure. This 1000 ml bottle has a balloon attached to its neck and an additional hole in its base fitted with a rubber stopper. You cannot inflate the balloon with the stopper in place, but remove the stopper and the balloon easily inflates. Replace the stopper, fill the bottle with water, remove stopper and Whoosh! – a geyser erupts!