Methods of Sterilization 157 



The study of sterilization, disinfection, and antisepsis 

 may be divided as follows : 



I. The sterilization and protection of instruments and 

 glassware. 



II. The sterilization and protection of culture media. 



III. The disinfection of the instruments, ligatures, etc., 

 and the hands of the surgeon, and the use of antiseptics. 



IV. The disinfection of sick-chambers and their con- 

 tents, as well as the dejecta and discharges of patients 

 suffering from contagious and infectious diseases. 



I. The Sterilization and Protection of Instruments 

 and Glassware. Sterilization may be accomplished by 

 either moist or dry heat. For the perfect sterilization of 

 objects capable of withstanding it dry heat is always to be 

 preferred, because of its more certain action. If we knew 

 just what organisms we had to deal with, we might be able 

 in many cases to save time and gas ; but though some non- 

 spore-producing forms are killed at a temperature of 60 C., 

 spore-bearers may withstand 100 C. for an hour; it is 

 therefore best to employ a temperature high enough to kill 

 all with certainty. The sterilizing apparatus, or " hot-air 

 sterilizer," shown in figure 22, is made with three walls. 

 The gas jets are inclosed within the space between the 

 outer and middle walls, C, and can be seen at F. The heat 

 ascends, warming the air between the two inner walls, 

 which ascends between the walls, K, then descends over 

 the contents, /, and escapes through perforations in the 

 bottom, B, to supply the draught at F, and eventually 

 escape again at 5. R is the gas regulator, T the ther- 

 mometer. 



Platinum wires used for inoculation are sterilized by being 

 held in the direct flame until they become incandescent. 

 In sterilizing the wires attention must be bestowed upon 

 the glass handle, which should be flamed for at least half 

 its length for a few moments when used for the first time 

 each day. Carelessness in this respect may result in the 

 contamination of the cultures. 



Knives, scissors, and forceps may be exposed for a very 

 brief time to the direct flame, but as this affects the temper 

 of the steel when continued too long, they are better boiled, 

 steamed, or carbolized. 



All articles of glassware are to be sterilized by an exposure 

 of one-half to one hour to a sufficiently high temperature 



