204 Microbes and You 



tion on a small scale, and the effectiveness of this compound is 

 measured in terms of "available chlorine." Since the principal 

 action depends upon oxygen, available chlorine is probably not the 

 best wav of expressing this oxidation reaction, according to some 

 sanitarians. When you purchase Chlorox, B-K, HTH-15, and 

 Diversol, you are buying hypochlorite compounds. 



During World War I a popular substance for treating wounds 

 was Dakin's solution ( 0.5% available chlorine ) , which was prepared 

 from sodium carbonate, chlorinated lime, and boric acid. It was 

 designed to control infections without harming the underlying 

 healthy tissue, which is essential for optimum healing of the 

 wound. When the sulfa drugs were added to our list of available 

 compounds just before World War II, Dakin's solution was rele- 

 gated to history. 



2. Bromine. Not enough work has been done with bromine to 

 make very specific statements about its possibilities as a disin- 

 fectant, but it has been shown to exhibit some disinfecting action. 

 This substance needs further investigation. 



3. Fluorine is the most active, chemically, of the four halogens, 

 and this high activity practically eliminates it as a disinfectant. 

 However, another application of this chemical in recent years has 

 been the fluoridation of public water supplies as a means of re- 

 ducing tooth decay. This topic will be discussed at more length 

 under the heading of dentifrices later in this chapter. 



4. Iodine. Compounds of iodine, as well as iodine alone, have 

 been used extensively through the years as disinfectants. Of all 

 the iodine compounds employed, however, standard tincture of 

 iodine is one of the most commonly used in the treatment of 

 wounds and for preparing the skin prior to surgery. A concen- 

 tration of 0.2 parts of iodine per million is quite effective in the 

 treatment of small quantities of water for drinking purposes, pro- 

 vided at least a thirty minute contact time is allowed for disin- 

 fection to occur. Iodoform (CHI3) has antiseptic properties, and 

 its slow decomposition in the presence of organic matter, with 

 the resultant liberation of free iodine, probably accounts for its 

 effectiveness. 



