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Hot-air steriliser

Object information


The absolute necessity for sterilising medical and surgical instruments in the laboratory to prevent the spread of infectious made the hot-air sterilisers, or hot-air ovens, important tools. A wide range of sterilisers were available during the early twentieth century as awareness of the importance of sterilisation increased.

All bacteria and spores are destroyed on glass and metallic items when heated in hot-air over a 30 minute period at 150°C (302°F), or faster at a higher temperature. Hot-air sterilisers are simply double-walled metal boxes, mounted on stands and heated from below by the flame from a Bunsen burner. The base of the oven contained firebrick plates that were replaced when broken or worn out. A thermometer was placed through the hole in the top of the box to indicate the internal temperature.

This hot-air steriliser is small, portable and versatile, and would have been used for sterilising instruments in surgery and chemical analysis, including scalpels and test tubes, at the Australian Institute of Tropical Medicine.

The Baird and Tatlock company was established in Glasgow in 1881 by Hugh Harper Baird (d. 1911) and John Tatlock (c.1842-1909). The company opened a London branch in 1889. The Baird and Tatlock partnership dissolved in 1896, with Baird operating in London, and Tatlock in Glasgow, beginning a series of disputes between the companies about naming rights to the Baird and Tatlock brand as each opened numerous branches and formed other partnerships.

To sterilise glass test tubes in the hot air steriliser, the tubes were placed on a metal rack inside the oven, the door closed and the ventilating slide on the door open. The gas Bunsen burner was lit below, and the oven heated over that flame. When the internal temperature reached 100°C (212°F), the ventilating slide was closed. At 175°C (347°F), the gas was extinguished and the oven allowed to cool with the door remaining closed. To avoid cracking the tubes, the door was open only after the oven temperature had dropped to 60°C (140°F). To keep metal items, such as knives, scissors, and forceps from being damaged, they were packed in a metal box and then placed inside the hot-air steriliser and heated to 130°C (266°F) for 30 minutes.

A small piece of paper inside this hot-air steriliser identifies it as 'Balwin's Pie Oven', probably a small joke amongst staff at the Institute. Alec Baldwin began work at the institute in 1924, appointed as acting director for a period, and investigating numerous diseases including hookworm, filariasis and Poliomyelitis (polio or infantile paralysis).

Physical description

A Baird and Tatlock Wax embedding oven. The oven is a cubic copper box with a hinged front door and a bent handle. The door has a circular ventilation aperture with a perforated open/close disk, a latch handle with a wooden knob and a plaque with the inscription 'BAIRD AND TATLOCK / GLASGOW & / EDINBURGH'. Inside is a perforated shelf supported by brackets.Two copper tubes are mounted in the top; the left hand tube is sealed with cork while the right hand tube is open. The base is buckled and corroded and has a ragged hole in the centre. There is much surface blackening and flaking to the lower parts of the oven. Inside is a piece of paper with the inscription 'COMMONWEALTH INSTITUTE OF HEALTH / With Complements...' on the front and 'Alex Baldwin's / Pie Oven' handwritten on the back.

Object information

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