. A laboratory guide in elementary bacteriology. Bacteriology. 8 General Fig. 1. Appara- tus for filling test- tubes. tube and stopcock (fig. 1), from which it can be run into sterile vessels. Test-tubes should contain 6-10 ec. of medium (about S cm. deep). Flasks are to be filled about three-fourths full. SpeciaIj Directions. Fill 15 test-tubes and preserve remainder of bouillon in larger flasks. EXERCISE VI. STERILIZATION OF CULTURE MEDIA. ExPLANATOEY. To accomplish this steam is used almost exclusively either as streaming steam or under pressure. The unconfined steam is appli
. A laboratory guide in elementary bacteriology. Bacteriology. 8 General Fig. 1. Appara- tus for filling test- tubes. tube and stopcock (fig. 1), from which it can be run into sterile vessels. Test-tubes should contain 6-10 ec. of medium (about S cm. deep). Flasks are to be filled about three-fourths full. SpeciaIj Directions. Fill 15 test-tubes and preserve remainder of bouillon in larger flasks. EXERCISE VI. STERILIZATION OF CULTURE MEDIA. ExPLANATOEY. To accomplish this steam is used almost exclusively either as streaming steam or under pressure. The unconfined steam is applied in an apparatus known as a steam sterilizer. Of the various patterns the Arnold is perhaps the most satisfactory. It is effective, economical in the use of gas, and does not allow the escape of large quantities of steam into the room, as a large part is condensed to be re- converted into steam. For student use the form shown in fig. 2 is very convenient. The method of using these different forms is identical. Always have plenty of water present before heating. The discontinuous method is most frequently employed. Exposure is made on three consecutive days for 20 minutes, be- ginning to count time when the material reaches the temperature of the steam, which will vary with different substances and the volume treated. Between successive steamings culture media should be kept under conditions favorable to bacterial development (room or incubator temperature). For the employment of steam under pressure the autoclave is essential. The lid should contain a thermom- eter as well as a steam gauge, safety and outlet valve. A thermo-regulator is also desirable. The following table gives the temperature corresponding to atmospheres of pressure: Atmospheres. Degrees C. 1 100 2 3 This table is only true when all of the air in the apparatus is replaced by steam, and hence the steam must be allowed to escape freely before the outlet valve is closed. A sin- g
Size: 1125px × 2221px
Photo credit: © The Book Worm / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1900, bookpublishermadis, bookyear1901
