22 



BACTERIOLOGY FOR NURSES 



milk is usually employed, the culture tubes being 

 exposed to 100° C. (212° F.) for fifteen minutes on 

 three successive days and in 

 the intervals kept at ordinary 

 room temperature; in this 

 way spores which develop 

 after the first steriUzation 

 may be destroyed after the 

 second or third. 



Filtration of fluids through 

 filter paper or absorbent cotton 

 is employed as an important 

 adjunct of sterilization. 



Instruments, such as for- 

 ceps, scissors, knives, metal syringes, and hypoder- 

 mic needles, are usually sterilized by boiling in a 

 2 per cent soda solution for ten minutes, before and 

 after using, the addition of ^0ii2t.,^;gveiitiiig_jTjst. 

 Platinum wires 

 used for trans- 

 ferring bacteria 

 are sterilized 

 by passing 

 slowly through a gas flame until red hot and allowing 

 them to cool before using. These wires must be 

 sterilized both before and after using, never being laid 



Fio. 8. — Arnold steam 

 sterilizer. 



Fig. 9. — Platinum wires. 



