A text-book of general bacteriology / by Edwin O. Jordan.

  • Jordan, Edwin O. (Edwin Oakes), 1866-1936.
Date:
1908
Catalogue details

Licence: Public Domain Mark

Credit: A text-book of general bacteriology / by Edwin O. Jordan. Source: Wellcome Collection.

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    thoroughly cleansed by boiling in soapsuds, or by soaking for an hour or more in the chromic-acid cleaning mixture. Potassium dichromate. 60 parts Water.300 “ Concentrated sulfuric acid.460 “ The sulfuric acid is added slowly with constant stirring. After thoroughly rinsing and drying, test-tubes and flasks are plugged with a good quality of ordinary non-absorbent cotton and placed without crowding in a hot-air sterilizer. The best hot-air sterilizers, like the Lautenschlager pattern (Fig. 2), Fig. 2.—Lautenschlager hot-air sterilizer. are fitted with thermometers and give a uniform temperature throughout. Experiments have shown that maintenance of a temperature of 170° C. for forty-five minutes to one hour is sufficient to destroy all bacteria, even those in the resistant spore-stage. Many ovens and hot-air sterilizers need to be carefully watched, because the temperature varies considerably in different parts. In the absence of exact temperature-control a very slight browning of the cotton is sometimes taken as evidence that the necessary temper¬ ature has been reached. Too great charring must be avoided. Instruments may be sterilized directly in the flame or wrapped in manila paper and heated in the hot-air sterilizer at 170° C. for