HOT AIR STERILIZERS 5 



Some form of apparatus in which sterilization can be effected by means 

 of hot air is to be found in all laboratories. 



To ensure efficient sterilization, the temperature must be maintained at approxi- 

 mately 180 C. for 30 minutes. Cotton-wool and paper are slightly scorched and 

 browned at this temperature. 



Hot air sterilizers. 



The various forms of hot air sterilizers differ from one another only in 

 details and in external appearance, the principles of construction and methods 

 of use being the same in all. 



1. Pasteur's sterilizer (fig. 2) is a double-walled cylinder of sheet iron 

 with a chimney outlet, and is fitted internally with a wire basket in which 

 the articles to be sterilized are packed. The top is closed by a lid, through 



FIG. 2. -Pasteur's hot air sterilizer. 



a hole in which a cork carrying a thermometer registering to 200 C. is 

 passed. The heat is derived from a large gas burner below, and when this 

 is lighted the heated air rising from the bottom of the stove circulates between 

 the inner and outer walls and escapes up the chimney. 



2. Chantemesse's and PoupinePs hot air sterilizers are rectangular and 

 cupboard-shaped. They are fitted internally with moveable shelves on which 

 the glass and other apparatus is arranged. 



[3. Hearson's hot air sterilizer (fig. 3) is similar in shape to Chantemesse's, 

 but is provided with an arrangement by which the gas is automatically 

 regulated when the temperature has reached the point for which the regu- 

 lator is set.] 



