A manual of bacteriology, clinical and applied / by R. Tanner Hewlett.

  • Richard Tanner Hewlett
Date:
1911
Catalogue details

Licence: In copyright

Credit: A manual of bacteriology, clinical and applied / by R. Tanner Hewlett. Source: Wellcome Collection.

Provider: This material has been provided by Royal College of Physicians, London. The original may be consulted at Royal College of Physicians, London.

    751/790 page 683
    Rideal-Walker Method 100 parts of phenol in 110, but is not absolutely constant in composition. ■ (3) All measures, pipettes, and test-tubes used for mating dilutions should be sterile. (4) The dilutions of the disinfectant and carbolic should be made with sterile distilled water. (5) The broth used for oulturing and subculturing should have the following composition : Lemco 20 grm. Peptone 20 grm. Salt 10 grm. Water 1000 c.c. The medium should be standardised to a reaction of -f 10 (Eyre's scale). (6) The loop used for subculturing should have an internal diameter of 3 mm., and be made with platinum wire of 27-28 B.W.G. (7) Growths in the subcultures should be obtained in those taken at not less than two and preferably at three of the time intervals (2i, 5, and 7\ minutes) from both the disinfectant and the carbolic solutions which correspond. (8) The temperature at which the determination is made should be noted, and the strength of carbolic varied accord- ingly (1-100 for 56°-62° F., 1-110 for 62°-67° F., and 1-120 for 67°-73° F. for B. typhosus), or the determination may be made at a standard temperature (e. (j. 20 C.) by warming (or cooling) the disinfectant and carbolic tubes in a water-bath. (9) When the organism does not form a uniform culture in broth, a suspension of an agar or other culture must be made in water and filtered. Sub-culturing in some cases (e. y. with B. pestis and B. anthracis) must be made on agar or other suitable culture medium. The method is an admirable one for determining the relative efficiencies of disinfectants on naked organisms in the absence of organic matter. But in practice disinfection is almost always carried out in the presence of organic matter, and various suggestions have been made with a view of
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