The Effect of Chemicals on Microorganisms 205 



Before the introduction of merthiolate and other organic mer- 

 curials, iodine as a tincture was without question one of the most 

 extensively used skin disinfectants. While iodine is still employed 

 by many hospitals, some of the newer compounds of mercury are 

 ascending the ladder of popularity. 



OXIDIZING AGENTS 



One of the better-known oxidizing agents used for disinfection 

 purposes is 3% hydrogen peroxide. The assuring sight of active 

 bubbling and frothing observed when this compound is put on a 

 cut is visual evidence to the layman that the process is effective. 

 Too much faith, however, has been placed in hydrogen peroxide, 

 particularly in deep, dirty wounds. Unless the compound is stored 

 in a cold place and is tightly stoppered, it may lose some of its 

 effectiveness. It does kill some bacteria, but its lack of penetrating 

 power limits its effectiveness to topical application on superficial 

 abrasions. 



ACIDS AND ALKALIES 



Many acids and alkalies are capable of destroying bacteria, but 

 their use is confined to locations other than in or on the body of 

 man and other animals because of their destructive action on 

 tissues. 



ALCOHOL 



Many persons, especiallv physicians and nurses, have much 

 greater faith in the germicidal power of alcohol than bacteriologi- 

 cal tests indicate is warranted. That magic bottle of 70% ethyl 

 alcohol is highly over-rated as a skin disinfectant prior to hypo- 

 dermic injections. Soap and water are probably just as effective, 

 or are better than alcohol, for mechanically removing skin organ- 

 isms. The time factor does not allow sufficient contact between 

 the alcohol and the bacteria to do much, if any, killing. The fact 

 that alcohol has a low surface tension improves the cleansing prop- 

 erties of the agent on skin that is normally oily, but soap and water 

 are still considered to be reliable substitutes for alcohol. 



The reason people do not contract more infections following 

 hypodermic injections after a "lick and a promise" with alcohol 



