Bacteriology for nurses / [Isabel McIsaac].

  • McIsaac, Isabel
Date:
1914
Catalogue details

Licence: In copyright

Credit: Bacteriology for nurses / [Isabel McIsaac]. Source: Wellcome Collection.

    39/208 (page 21)
    0 0 0 o o o 0 0 % 0^ plished by means of an autoclave, which is a strong iron cylinder standing upright, closed at the bottom and furnished with a tight- i fitting lid, and provided with a ther- mometer, a steam valve, a safety valve, and a gauge whereby the tem- perature and pressure may be regu- lated, heat being furnished by Bunsen gas burners or by indirect steam from a central boiler. For culture media in tubes an exposure of five minutes at 120° C. (248° F.) is sufficient to destroy all bacteria, but for media in bulk an exposure of fifteen minutes fig.6. is necessary. Certain culture media are injured by exposure to great heat under pressure, and this fact, together with the extraordi- nary resistance of the spores of certain species of bacteria, led to the employment of frac- tional or discontinuous sterili- zation. The ordinary Arnold steam sterilizer used in the Fig.7.-Bunsenburner, kitchen for the sterifizatioR of ■ Autoclave. a. Safety-valve. b. Blow-off pipe. c. Gauge.