44 



APPLIED BACTERIOLOGY FOR NURSES 



(3) Moist Heat. — It has been found that the presence 

 of moisture markedly increases the destructive effect 

 of heat. The simplest method of combining these two 

 factors is to boil the articles to be sterilized in water. 

 Surgical instruments are usually sterilized in this way, 



Fig. 19. — Hot-air sterilizer (McFarland). 



and so are catheters, douche-nozzles, hypodermic nee- 

 dles, etc. 



(4) Live Steam. — Another method of using moist 

 heat is by means of live steam in a steam sterilizer. 

 The accompanying figure shows the construction of the 



