CHAPTER V 



DESTRUCTION OF BACTERIA BY CHEMICALS 

 AND THEIR PRACTICAL USE 



IT has been shown how bacteria can be killed by heat, 

 and now the chemical methods of destroying infective 

 material will be discussed, and how this may be done 

 practically. Chemicals either in solution or as gas 

 are supposed to kill bacteria by one of several methods. 

 The whole bacterial body may be destroyed or the 

 protoplasm may be entered by a diffusion of the 

 substance through the cell wall with consequent 

 coagulation or solution. It is said also that the rapid 

 withdrawal of water by some salts may be fatal to the 

 microorganism. 



There is some confusion as to the terms used for 

 chemical bacteria-killing, and for this reason it 

 may be well to start out with Park's classification, 

 (l) Attenuation is when the pathogenic or vital func- 

 tions of the bacteria are temporarily diminished. (2) 

 Antiseptic action is when the bacteria are not able to 

 multiply, but are not destroyed; they will reproduce 

 when suitable conditions for life are restored. (3) In- 

 complete sterilization or disinfection is when the vege- 

 tative forms but not the spores are destroyed. (4) 

 Sterilization or disinfection is when both vegetative 

 and spore forms are destroyed; this implies also the 



