254 STERILIZATION, ANTISEPSIS AND DISINFECTION 



Clinical Thermometers, Dental Instruments. Clinical ther- 

 mometers and dental instruments are ethically on a par with the 

 common drinking cup and the common towel. Barbers' razors and 

 brushes also belong to this group. The cost of such instruments is 

 prohibitive for individual use, however, and their disinfection appears 

 to be the practical solution of the problem. In hospitals the ther- 

 mometers can be sterilized readily, first, by wiping them carefully 

 to remove adherent mucus, then immersing them in 5 per cent, for- 

 malin solution, 1 where they remain until wanted again. A thorough 

 rinsing in water will remove the formalin. The clinician who has an 

 extensive visiting practice cannot afford individual thermometers; 

 for practical purposes his thermometer can be kept free from bacteria 

 if it is washed each time in running water until free from mucus, and 

 kept in a metallic case containing 10 per cent, formalin solution pre- 

 pared daily. Running water will remove all traces of formalin before 

 use. At least two hours should be allowed before sterilization is 

 regarded as complete. Several thermometers may be required to 

 permit of this period of sterilization for each individual instrument. 



Dentists' instruments almost without exception can be safely 

 sterilized in a boiling 5 per cent, solution of washing soda (sodium 

 carbonate) within five minutes' exposure. If they are then wiped 

 dry there is little danger of rusting. The sterilization of dental mouth 

 mirrors is a problem which would appear to require special investiga- 

 tion. 



1 A covered container is required; the fumes of formaldehyde are very irritating to 

 the patient. 



