DISINFECTION STUDIES 215 



't = ^(«-^> (2) 



This expression on integration becomes 



fc = flog-^ (3) 



t a — X 



which is the familiar equation of the velocity of a monomolecu- 

 lar reaction and often spoken of as the logarithmic law. 



It is perhaps well to emphasize that this formula represents 

 the course of events taking place and makes no pretence of indi- 

 cating the mechanism involved. It indicates the effect of active 

 mass. Although the value of k will be greatly modified by 

 change in the nature and intensities of the forces concerned, the 

 essential form of the velocity curve will in no wise be altered 

 since it is fixed by itis inherent relation to the numbers of reacting 

 molecules and by this factor only. The factor k may include, 

 by its very definition, many influences. Therefore, to establish 

 experimentally the apphcability of the monomolecular law in 

 any given case, all the influences must be kept constant while 

 the effect of mass is being observed. For the present, our knowl- 

 edge of the mechanism of a monomolecular reaction is nil. We 

 may only guess that it involves complex electronic relations 

 (cf. Tohnan (1921) and Dushman (1921)). Note that k in the 

 final expression happens to be designated as the velocity con- 

 stant since time is inversely related to it. If log (a —x) be plotted 

 against time in the above equation, the resulting graph will be 

 a straight line. 



The above theoretical considerations have therefore led us to 

 the deduction of a logarithmic equation that should hold good 

 under the ideal conditions imposed. When we turn to actual 

 experimental observations on monomolecular chemical reactions 

 it is found that this logarithmic law holds good, according as we 

 are able to maintain the ideal conditions. There may occur 

 deflections from the true logarithmic rate at the beginning and 

 the end of the reaction so that instead of a straight line plot 

 of the results, we get a somewhat s-shaped curve. If conditions 



