DISINFECTANTS 



67 



where t is the killing time and K the deathrate constants 

 This constant was computed for each time interval and 

 its average for each concentration is given at the bottom 

 of Table 14. 



TABLE 14 



Action of various concentrations of mercuric chloride on spores 

 of B. anthracis. The figures represent the number of viable spores 

 after various times of exposure. K is the deathrate constant (From 

 Kronig and Paul, 1897.) 



The values of K increase with the concentration, but 

 not proportionally. In 1908, Watson, using the data by 

 Chick (1908), showed that the relation of the death rate 

 to the concentration is best expressed by an equation in 

 which the concentration c is raised to a power n. This 

 equation is 



initial number 



Ktc" = log 



survivors 



1. See p. 17. 



