This Soda Siphon was popular in the 1920s and 1930s - it was filled with water and aerated by placing a CO2 gas bulb into a special tool which was screwed into the neck of the siphon. When the lever was depressed the gas pressure forced aerated water out of the spout. It looked rather grand amongst the bottles of alcohol in a drinks cabinet.
The modern equivalent would be the Soda Stream machine - it also aerates a bottle of water using a CO2 gas cylinder.
Kindly sourced by Tinakori Antiques.