. Pathogenic microörganisms; a practical manual for students, physicians, and health officers . f the incubator. It is essential, however, to use method b §0 THE CULTIVATION OF MICROORGANiSMS boiling temperature, when titrating meat juice which has not been heated above50° C. (or up to the boiling-point) for the purposeof dissolving added peptoneand salt. The boiling in the casserole is needed to approximate the laterconditions when the medium is boiled and sterilized. This method of titrationas given below is the standard method. It is often misapplied, however,when used for the titration of
. Pathogenic microörganisms; a practical manual for students, physicians, and health officers . f the incubator. It is essential, however, to use method b §0 THE CULTIVATION OF MICROORGANiSMS boiling temperature, when titrating meat juice which has not been heated above50° C. (or up to the boiling-point) for the purposeof dissolving added peptoneand salt. The boiling in the casserole is needed to approximate the laterconditions when the medium is boiled and sterilized. This method of titrationas given below is the standard method. It is often misapplied, however,when used for the titration of media already heated to the error in its results is due to the fact that the more phenolphthalein isheated, the less sensitive and accurate it is as an indicator. Technic.—Room temperature method: 5 of medium to be tested, 45 ofdistilled water^ and 1 of the phenolphthalein solution are mixed in a cas-serole. (When agar is titrated, the water should be warmed to about 30° adding the hot agar.) If no pink color is present, the medium is FiQ. 23.—Hot-air sterilizer. Lautenschlagetform. While the mixture sibeing stirred twentieth-normal solution of sodium hydrate(^0 NaOH) from a burette is run in until a delicate pink tinge is color should not disappear with stirring. (See page 91 for the calcula-tion for correction.) Boiling Temperature.—Standard method: 5 of medium to be tested and45 of distilled Water are mixed in the casserole and boiled for one minute,then 1 of the phenolphthalein solution is added. If no color is presentthe medium is acid and while hot the twentieth-normal solution of sodiumhydrate (^^ NaOH solution) is run in from a burette until a faint but distinctpink color appears. This color must remain on stirring, otherwise more alkali 1 Distilled water, freshly boiled and cooled, should be used for very accurate results,since the CO2 has been driven off by the boiling and is
Size: 1626px × 1537px
Photo credit: © Reading Room 2020 / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookauth, bookcentury1900, bookdecade1910, bookidcu31924000235212
