122 DISINFECTION— STERILIZATION— DISINFECTANTS 



is a receptacle for a relatively small quantity of water and 

 means for conducting the steam generated by boiling this 

 water to the objects to be treated, which are usually placed 

 immediately above the water. Surgical instruments may 

 be most conveniently sterilized by boiling or by steaming in 

 especially constructed instrument sterilizers. If boiled the 

 addition of carbonate of soda, about 1 per cent, usually 

 prevents injury. 



Fig. 75. — A battery of two horizontal autoclaves in one of the author's 

 student laboratories. Steam is furnished direct from the University central 

 heating plant. 



Steam under pressure affords a much more rapid and 

 certain method of destroying organisms. Fifteen to twenty 

 pounds pressure corresponding to temperatures of 121° to 

 125° is commonly used. Variations depend on the bulk and 



