366 PHYSIOLOGY OF BACTERIA 



C 

 Only a n = 1, we have Q17 = ^r as Cooper and Haines assumed; but 



(^ 1 



for n larger or smaller, this ratio varies. 



Applying to the experimental data by Cooper and Haines the 

 values w = 4 for phenol and n = 0.5 for H2O2, (Table 110) and 

 assuming arbitrarily n = 0.5 for toluquinone, the following tem- 

 perature coefficients are obtained: 



for phenol, Qio = 4.2 instead of 1.43 by Cooper and Haines 

 for H.2O2, 1.16 instead of 1.30 



for toluquinone, 2.58 instead of 6.6 



For the first two compounds, similar values had been claimed which 

 are probably not similar, and the high coefficients for substances 

 like toluquinone might be explained by a small value of n. The 

 claims of Cooper and Haines are improbable, and cannot be con- 

 sidered proved until all w-values have been ascertained. 



(g) OTHER THEORIES OF CHEMICAL DISINFECTION 



In 1919, Traube made a very general statement that 

 all toxic action is brought about by surface reactions. 

 He also extended this theory to disinfection: ^'If we 

 disregard the oxidizing disinfectants like ozone, peroxide, 

 and hypochloric acid, it may well be claimed that the 

 action of the other disinfectants is based exclusively 

 on physical processes. Salts of heavy metals, like 

 mercury or copper, cause death by irreversible pre- 

 cipitates, while most of the acids, bases, and organic 

 disinfectants, largely by means of their very strong 

 swelling and solving properties, produce such changes 

 in the bacterial cells that they must perish." 



The two papers are limited to the discussion of a 

 few series of disinfectants where a proportionality 

 between surface tension depression and disinfecting 

 power exists, but even in these selected examples, 

 exceptions occur. While it cannot be denied that 

 depression of surface tension might be a cause of 



