LABORATORY STERILIZATION 245 



of solution will kill all pathogenic bacteria in a very short time; a 

 solution of 1 to 500 strength will even kill anthrax spores within a 

 few hours. 



The advantage of bichloride of mercury as a germicide resides in 

 its great bactericidal powers. Its disadvantages are: its marked 

 affinity for protein which, in the case of wounds, may lead to local 

 necrosis of tissue, or in greater concentrations, by absorption, to 

 toxic action on the kidneys, intestinal tract, and even the central 

 nervous system. It is unreliable for the disinfection of sputum, feces, 

 urine, purulent discharges, and other excreta, and it should never be 

 employed in the sterilization of instruments or eating utensils. Linen 

 soiled with blood or stained in any way should not be immersed in 

 bichloride, for it acts as a mordant and "sets" the stain. 



2. Silver Salts. Silver nitrate is a much less efficient germicide 

 than mercuric chloride, but it is quite extensively used upon mucous 

 membranes. The soluble organic compounds of silver, as Protargol, 

 are less irritating than the inorganic salts and apparently nearly as 

 efficient. 



Oxidizing Solutions. 1. Potassium Permanganate, KMnO 4 . Potas- 

 sium permanganate is a strong disinfecting agent, but it is almost 

 instantly reduced and rendered inert by organic substances. This 

 greatly impairs its practical value. Nevertheless, it is used in surgical 

 asepsis and also in wells and cisterns which are to be freed from 

 pathogenic bacteria. A strong solution is thrown into the well or 

 cistern, enough to impart a very pronounced pink color to the water, 

 and left for several hours. The water is fit for use when the last traces 

 of color are removed by dilution or emptying and washing out the 

 reservoir. This process is spoken of as "pinking" a well. 



2. Hydrogen Peroxide, H 2 O 2 Hydrogen peroxide is a valuable 

 germicide, applicable to the cleansing of mucous surfaces and wounds. 

 It is readily reduced to H 2 O and nascent oxygen in contact with 

 organic substances, and its efficiency is attributable to the latter 

 element. It is essential that the peroxide actually reach the organism 

 to be destroyed in order to be effective. Usually hydrogen peroxide 

 is quite acid in reaction and irritating for this reason. 



3. Chlorinated Lime or "Bleach." Chlorinated lime is an excellent 

 deodorant and germicide when it is fresh, but it soon loses chlorine 

 when exposed to the air. Nascent chlorine is liberated from aqueous 

 solutions, and reacts with water to form nascent oxygen and hydro- 

 chloric acid, according to the equation 2C1 + H 2 O = 2HC1 + O. 



