CHAPTER XV 
BISINFECTION 
Disinfection. By disinfection is meant the destruction of disease- 
producing organisms. For this purpose, nature has provided very 
important agents, such as sunlight and drying, but these are not 
available or sufficient to destroy al! 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 practi- 
tioner 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 differ- 
ent species of organisms. The failure resulting from the many efforts 
to disinfect stables, pens, kennels and yards has caused much skepti- 
cism 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 relative to the species themselves, the material 
with which they are mixed and the chemicals used. 
Different species. The bacteria used by different investigators to 
test the efficiency of 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 anthrax. The difficulty 
in accepting the results of many of the older experiments is that 
organisms were used which are very unlike those for which these 
disinfectants are now wanted. The practical value of the more 
recent experiments is greater because they have dealt with species of 
bacteria with which most of the work of disinfection has to do. 
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