CHAPTER XIV 



DISINFECTION. 



§ 452. Disinfection. By disinfection is meant the de- 

 struction of infectious disease-producing organisms. For this 

 purpose, nature has provided very important agents, such as 

 sunlight and drying, but these are not available or sufScient to 

 destroy all infecting bacteria in all infected places within the 

 necessary time limits. To supplement these natural forces, a 

 large number of chemical substances possessed of germicidal 

 powers have been brought into service. If, however, the 

 results of the test experiments with these different substances 

 are reviewed, one is impressed with the discrepancies, if not 

 contradictory conclusions, recorded concerning their value. In 

 view of these facts the practitioner is often at a loss to know 

 just what chemicals to use, or how to apply them under different 

 conditions and for the destruction of different species of organ- 

 isms. The failure resulting from the many efforts to disinfect 

 stables, pens, kennels and yards has caused much skepticism 

 concerning the efficiency of many reported disinfectants. In 

 order to rightly understand the reason for the differences in 

 results of the test experiments or the lack of uniformity in the 

 application of the various disinfecting substances, it is well to 

 take into account certain fundamental facts. 



I . The bacteria used by different investigators to test the 

 efficiency ot certain substances have not been the same. The 

 vital resistance of the various species is very different. The 

 results obtained in testing disinfectants on the spirillum of 

 Asiatic cholera or the bacterium of bubonic plague give but 

 little information relative to the value of the same disinfectants 

 • when used for the destruction of the bacteria of glanders, 

 tuberculosis or hog cholera. Thus the difficulty in accepting 

 the results of many of the older experiments is that the 



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