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VETERINARY BACTERIOLOGY 



rise as quickly as possible to 15 pounds to the square inch, or 

 one additional atmosphere. This gives a temperature of about 

 121. Material to be sterilized should be allowed to remain 

 fifteen minutes usually. If large bulks, such as flasks of media, 

 are to be sterilized, a longer period must be allowed in order that 



Fig. 50. Autoclave for sterilizing by steam under pressure. 



the media may be completely heated through. If very small 

 quantities of material are bein^ sterilized, a shorter period may 

 be used. When properly carried out, sterilization by this method 

 will certainly destroy all the bacteria present. Its principal 

 disadvantage is that certain organic substances may be decomposed 

 at this temperature. 



