52 STERILIZATION AND DISINFECTION. 



temperature of about 75 C. for two hours. This does not 

 alter the composition of the milk, and it will keep on ice for 

 several days. 



Disinfection of Instruments and Materials Used in the 

 Operating-room. 



The same care that is used in the laboratory must be 

 observed in the operating-room. Everything should be abso- 

 lutely sterile. Any instrument, towel, sponge, or ligature 



FIG. 17. 



Portable steam sterilizer for instruments. 



that falls to the floor or comes in contact with any unsteril- 

 ized object should be removed at once and resterilized before 

 it is used again. 



Instruments may be sterilized by dry heat; but it is prefer- 

 able to subject them to steam or to boil them in a 1 per cent, 

 solution of sodium bicarbonate, which prevents rusting and 

 does not dull the edge of sharp instruments. They can either 

 be placed directly in the water or be wrapped in towels or 

 pieces of gauze. As soon as they are removed from the ster- 

 ilizer (Fig. 17) they are immersed in sterilized or distilled 

 water or in a 5 per cent, carbolic acid solution. Mercuric 

 chloride is unsuited for the disinfection of instruments because 

 it dulls the edges of cutting instruments, and also deposits 

 mercury on their surfaces. 



