STERILIZATION 



ordinary culture media are uninjured by the exposure neces- 

 sary for sterilization. When sugar media are heated in the 

 autoclave, they are frequently darkened because of a change 

 produced in the sugar by the 

 high heat. This change is 

 known as caramelization. A 

 committee of the American 

 Public Health Association 

 has, however, recently agreed 

 that the autoclave may be 

 used for the sterilization of 

 these media, providing the 

 temperature does not get 

 above 120 C., steam pressure 

 fifteen pounds, and the ex- 

 posure is not longer than 

 fifteen minutes. 



An exceedingly convenient 

 form of autoclave is that 

 manufactured by Bramhall 

 and Dean, and shown in 

 Figure 35. 



The intermittent method 



of sterilization has been used 



FIG. 35. Autoclave for use with steam 

 under pressure. 



for sterilizing blood and other protein material by using a 

 temperature below the coagulation point of the material to be 

 sterilized, e.g. 55 to 60 C. It is necessary, however, to make 



