STERILIZATION BY HEAT. 



75 



that is all the heat to which the articles have been sub- 

 jected during their stay in the chamber. In this light, 

 while steam under pressure may answer very well for 

 routine sterilization, still it presents insurmountable 

 obstacles to its use in more delicate experiments where 

 time-exposure to definite temperature is of importance. 

 Nevertheless, for general laboratory purposes, sterili- 

 zation by steam under pressure has so much to recom- 

 mend it in the way of economy of time and certainty 

 of accomplishment that it has practically superseded 

 the older methods of sterilization by streaming or live 



FIG. 8. 



Steam sterilizer, pattern of Koch. 



steam ; and in most laboratories the original styles of 

 steam sterilizers are rapidly giving way to some one or 

 another of the modern forms of autoclave. 



