Two empty nitrous oxide cylinders with union, English, 1915-1940

Nitrous oxide or laughing gas was used as an anaesthetic for dentistry from the 1840s. George Barth of Barth and Co – who produced these cylinders – was one of the first people to liquefy the gas in 1868.

Each of these cylinders contains 25 gallons (114 litres) of liquid nitrous oxide. The average patient required approximately six gallons (27 litres.) Dentists preferred having two cylinders to hand in case one stopped working or ran out during an operation.