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

  • Edwin O. Jordan
Date:
1931
Catalogue details

Licence: In copyright

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

    27/830 page 25
    Potassium dichromate. 60 parts or Sodium dichromate. 52 “ Water. 300 “ Concentrated sulphuric acid. 460 “ The sulphuric acid is added slowly, with constant stirring. After being thoroughly rinsed and dried, test-tubes and flasks are plugged with a good quality of ordinary nonabsorbent cotton. The plug should completely fill the opening, but a tight plug is unnecessary and hinders easy manipulation. A simple method for test-tubes is to use enough cotton so that the empty tubes may be picked up by the plug. The plugged tubes and flasks are Fig. 2.—Lautenschlager hot-air sterilizer. placed without crowding in a hot-air sterilizer. The best hot-air sterilizers, like the Lautenschlager pattern (Fig. 2), are fitted with thermometers and give a uniform temperature throughout. When the test-tubes and flasks are to contain media which is later auto¬ claved in them, it is only necessary to heat long enough to set the plugs. This is accomplished in fifteen to twenty minutes’ exposure to a temperature of 170 to 190 C. For the destruction of all bacteria, even those in the resistant spore stage, forty-five minutes to one hour is sufficient. In many ovens and hot-air sterilizers
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