158 APPLIED BACTERIOLOGY FOR NURSES 



Under these conditions the steam generated not only 

 kills bacteria more readily than steam generated at 

 atmospheric pressure, but also has a much greater 

 power to penetrate to the interior of bulky objects, such 

 as mattresses, bundles of dressings, or clothing. Steam 

 under pressure is, therefore, a more valuable disinfect- 

 ant. A good example of high-pressure steam sterilizer 

 is shown in Fig. 50. 



Fig. 51. — Diagram showing construction of a pressure steam 

 sterilizer. 



Another excellent type of pressure steam sterilizer 

 consists of an outer and an inner jacket made of sheet 

 metal. The space between these two, A, is half-filled 

 with water, which is heated either from below by a 

 gas burner or by means of steam circulating in coils ((7) 

 within. As the w^ater grows hotter, the air in the dis- 

 infecting chamber, B, becomes rarefied, and may be 



