162 TRANSACTIONS OF THE 
IS DISINFECTION A REACTION OF THE 
FIRST ORDER? 
(Preliminary Communication) 
BY L. F. SHACKELL. 
In an extended research upon the velocity with 
which bacteria are killed by various disinfectants, Miss 
Chick (1) concluded that the progress of disinfection is 
similar to that of a monomolecular reaction. Arrhenius 
(27) in reviewing the data obtained by Miss Chick and by 
others says: “.... on the whole these reactions show 
such a regular progress with time, that their monomolec- 
ular nature is obvious. This circumstance indicates that 
every bacterium or yeast cell or red blood-corpuscle acts 
as if it were a single molecule in regard to the substance 
reacting upon it. This seems from a biological point of 
view extremely difficult to understand.” Although 
Arrhenius takes into consideration the question of vari- 
ability of the organisms in their resistance to deleterious 
substances, he concludes that “the different lifetime of 
the different bacteria does not depend in a sensible degree 
on their different ability to withstand the destructive 
action of the poison. Instead of this a certain fraction of 
the bacilli still living dies in one second, independent of 
the time during which they have been in contact with 
the poison.” 
_ In a more recent investigation of this same question 
Lee and Gilbert (*) attempt to show that the law of mass 
action may be applied to the process of disinfection. In 
the majority of their experiments, however, the constants 
evaluated by Lee and Gilbert from the equation for a 
monomolecular reaction are not convincingly “‘constant’’. 
In fact, from the data in Table V of Lee and Gilbert’s 
