174 



CHEMICAL INFLUENCES. 



while a few will remain resistant for a considerable length of time. This 

 is the case with all disinfectants. The disinfecting process resembles in 

 many ways a slow chemical process, as the inversion of cane sugar. In 

 the beginning, the reaction is very rapid, because plenty of the cane 

 sugar is present; after a certain time, the action is much slower, because 



4-000 



3500 

 3000 



000 



1 500 



IOOO 



5oo 



to 



20 



30 



FIG. 56. Curve of disinfection. Spores of Bact. anthracis in mercuric chloride solu- 

 tion. (After Chick.) 



most of the sugar is decomposed; finally it seems to nearly cease. It is 

 the same with disinfection ; at first many bacteria are present, but they are 

 killed rapidly and only a few are left. These few die much more slowly 

 than the first ones, not because they were more resistant, but simply as a 

 consequence of the chemical law that the less there is of the react- 

 ing substances the slower is the rate of reaction. The curves in 



