122 ANTISEPTICS AND DISINFECTANTS 



water destroys the typhoid bacilli. Even nascent copper kills the 

 typhoid bacilli, so that copper foil in drinking water has the power, 

 after a few hours contact, of destroying bacteria in the water. 



The silver salts are useful in medicine as disinfectants, especially 

 on mucous surfaces. The nitrate of silver is one of the most valu- 

 able of all the preparations; it is about a fourth as efficient as bi- 

 chloride of mercury and is not nearly so toxic. Some of the albu- 

 minates of silver are useful because of their non-irritating action. 



Acids, especially the mineral ones, are valuable disinfectants in 

 not too dilute solutions. They act chiefly as inhibitors of growth 

 rather than destroyers of bacterial cells. In the healthy stomach, 

 hydrochloric acid acts as a normal disinfectant, and in disease, 

 where it is absent, it must be added in order to prevent decomposi- 

 tion of food. Boric acid is useful in medicine on mucous 

 membranes. 



The halogens, iodine, bromine and chlorine, are active agents 

 for the destruction of bacteria. The cheapest of these is chlorine. 

 It acts best in contact with moisture, since it decomposes the mole- 

 cule of water combining with the hydrogen to form free HC1 and 

 setting free oxygen. 



Dry chlorine gas (45 percent) failed to kill dry anthrax spores in 

 one hour, but when moisture was introduced 4 percent chlorine 

 killed the spores. 



Chloride of lime, chlorinated lime, in i percent solution kills most 

 bacteria in 1-5 minutes. Iodine preparations like chlorine ones 

 are very powerful. They are of great use in medicine; ordinary 

 tincture of iodine painted over infected areas acts as a powerful 

 germicidal agent. It is too expensive to use in house disinfection 

 and it is exceedingly destructive to all metallic objects. A 5 percent 

 solution in 50 percent alcohol acts as a splendid disinfectant for 

 intrauterine injection in puerperal sepsis. It is now said that 10 

 percent iodine tincture in 70 percent alcohol is the most efficacious, 

 practical, medical disinfectant. Many claim it to have the highest 

 penetrating powers. 



