176 GENERAL THERAPEUTICS FOR VETERINARIANS 



metallic salts, particularly corrosive sublimate and silver nitrate, 

 act as antiseptics (formation of a precipitate of metallic albumi- 

 nate). Formaldehyde acts in the same manner. 



2. A specific toxic action, narcotic to a certain extent, is attrib- 

 uted to the benzol derivatives, especially the cresols (creolin, 

 lysol, tar, creosote) and carbolic acid. 



3. By oxidation, potassium permanganate (KMn04), potassium 

 chlorate (KCIO3), hydrogen peroxide (H2O2), and other drugs act 

 as disinfectants. 



4. Reduction (withdrawal of hydrogen). Chlorine and many 

 chlorine compounds operate by reduction. Corrosive sublimate, 

 zinc chloride and iron chloride, for example, act in part in this way. 

 The chlorine withdraws hydrogen from the bacteria, thus breaking 

 up and decomposing the albumin molecules, while the chlorine 

 and hydrogen combine to form hydrochloric acid; the chlorine 

 also decomposes the water, setting free nascent oxygen, which 

 oxidizes the bacteria. 



5. Through a change of the reaction, most antiseptics act as 

 disinfectants, especially the acids and acid chlorides (also the 

 acid-reacting corrosive sublimate). Bacteria grow upon a weakly 

 alkaline or neutral culture media and merely a change of reaction 

 is sufficient to retard their development. Growth is also effected 

 by a considerable increase of the alkalinity (alkalies). 



6. By dissolving the cell membrane, alkalies, organic acids 

 (vinegar) and soaps operate as disinfectants. 



7. Precipitation. Corrosive sublimate and the other metallic 

 salts (iron sulphate) precipitate the bacteria from the fluids in 

 which they are suspended. 



8. Absorption. Freshly heated charcoal absorbs gases and 

 acts as an antiseptic and deodorizer. 



9. Withdrawal of water. Concentrated salt solutions (e.g., 

 sodium chloride) and glycerin act in this way. Finally, a purely 

 mechanical fixation is produced by certain substances like oil 

 paints, tar and pastes. 



As will be seen from the foregoing, the method of action of 

 a disinfectant may often be multiple. Corrosive sublimate, for 



