76 CLINICAL BACTERIOLOGY. 



space. The former is intended to receive the substances to 

 be sterilized, while the latter is intended for the water. The 

 bottom of the cylinder is heated, the water is made to boil, 

 and the steam generated streams through the perforated 

 partition into the upper sterilizing chamber, which is closed 

 by means of a loosely applied cover. Exposure to live 

 steam for from half an hour to an hour, according to the 



Fig. 10. Koch's steam sterilizer. Fig. n. Koch's steam-chest. 



amount of fluid or the size of the articles to be sterilized, 

 suffices, as a rule, to free these from germs. 



It is useful, when an adequate water-supply is available, 

 to connect the Koch steam-cylinder with a constant water- 

 bath. For sterilization with steam under pressure at a tem- 

 perature of 1 10 C. (230 F.) (almost I i^ atmospheres) or 

 120 C. (248 F.) (two atmospheres of pressure), special 

 apparatus (digesters, autoclaves) are required, whose con- 



