THE HOT-AIR STERILISER 



31 



sterilised ; when the cotton-wool becomes slightly browned, 

 it may be taken as a sign that the sterilisation of the 

 objects is complete. The platinum inoculating wires, for- 

 ceps, etc., are best sterilised by passing through the flame 

 of the Bunsen burner. 



The Steam Steriliser. — This is a cylindrical vessel of 

 copper about 1 metre high by about 30 centimetres wide, 

 jacketed with felt or other non-conducting material, and 



Fig. 2. — Hot-air Steriliser. 



provided with a lid. The lid is also covered with felt, and is 

 perforated to receive a thermometer. Inside the vessel is a 

 diaphragm or grating about two-thirds down which divides 

 the interior into two portions : the upper, or ' steam- 

 chamber,' and the lower, or * water-chamber.' This part 

 is fitted with a water-gauge to indicate the water-level. 

 The apparatus stands upon three legs, and is heated by 

 two ordinary Bunsen burners, or, better, by a large 

 Fletcher burner. 



