CHAPTEE XXVII 

 GERMICIDES — DISINFECTANTS 



Germicides or Disinfectants are agents which will kill or 

 destroy microorganisms and their spores. They may produce this 

 action by coagulating the albuminous constituents of the organisms 

 f metals and their salts), by oxidizing or deoxidizing the cells (potas- 

 sium permanganate and the sulphides), or by a specific action against 

 them. 



Antiseptics are agents which prevent or hinder the growth of 

 microorganisms, without necessarily killing them. There is little 

 difference between disinfectants and antiseptics. Most antiseptics 

 are disinfectants in strong solution or concentration and all disin- 

 fectEints are antiseptics in weak solutions. 



A few agents are usually classified as antiseptics because they 

 are ordinarily used in sufficient concentration to prohibit the growth 

 of organisms, but too weak to destroy them. The principle antisep- 

 tics are boric acid, methylene blue, pyoktanin, etc. 



Deodorizers are agents which destroy offensive odors and do not 

 necessarily possess antiseptic or disinfectant properties, although 

 most deodorizers are disinfectants. They produce their action 

 largely by oxidizing or deoxidizing fetid compounds by abstracting 

 hydrogen from them. The most important are chlorine, lime, for- 

 maldehyde, charcoal and potassium, permanganate. 



CLASSIFICATION OF GERMICIDES 



Disinfectants may be classified according to their physical or 

 chemical structure, or according to their therapeutic use. For con- 

 venience of study they will be discussed in detail under the former 

 head and a therapeutic grouping made later. 



The principal agents used as disinfectants are: 



1. Heat. 



2. Metals and their salts. 



3. Benzene derivatives. Phenol group. 



4. Aniline derivatives, Pyoktanin, etc.. 



5. Oxidizers and deoxidizers. 



6. Halogen group. 



Y. Miscellaneous. 



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