68 



MANUAL OF BACTERIOLOGY. 



water and the bottles are placed in it; it has been found to 

 keep up a temperature of about 75 C. 



The Autoclave. The autoclave is an instrument de- 

 signed for sterilization by steam under pressure. It was 

 invented in France but is now used extensively in all parts 

 of the world. Steam generated at the ordinary atmospheric 

 pressure is much less destructive to bacteria, and especially 



Vic.. 15. 



Autoclave. 



to their spores, than steam in the autoclave at a pressure of 

 an additional one-half to one atmosphere; the steam then 

 reaches a temperature of about 110 to I2OC. Under 

 these conditions culture-media may be sufficiently sterilized 

 in the autoclave in fifteen minutes, and at a single steriliza- 

 tion. The autoclave consists of a metal cylinder with a 



