3l ‘Porton pot’ used for continuous fermentation at the Microbiological Research Establishment, Porton Down dating from early to mid 1950s, comprising a clear glass vessel with spout towards the bottom, stoppered with a bung. Circular metal rings at the top and bottom are connected with thin metal columns secured on top with nuts. Rubber tubes are connected to the top of the vessel and inside is a stirring device comprising a single length of metal suspended in the centre of the flask bent in a tear-shaped loop at the bottom ‘Porton pot’ laboratory glassware 1950-1955