302 MORRIS LOEB 



As equivalent quantities of A and B were used, 



tj 

 at 



Integrating, -- = C^+constant. 

 A x 



Calculating this constant from the initial conditions d= 



#=0, constant =, and consequently 

 A. 



x 



At A-x 



A is the amount of permanganate required at the first titra- 

 tion, and A -x represents the amount of each subsequent one, 

 after the lapse of t minutes. We possess all the data for calcu- 

 lating C. This coefficient has been shown by Hood to depend 

 upon the temperature, to be augmented by the presence of 

 free [151] acid, and diminished by the presence of neutral 

 salts not participating in the reaction. It is consequently 

 decreasing continually during the reaction, most noticeably, 

 however, toward the end. Furthermore, if magnetism is of 

 influence, the values of C must show it. In order to eliminate 

 the other influences, I have sought to take the samples from 

 corresponding solutions at the same intervals of time, and 

 have varied the conditions somewhat by changing the tem- 

 peratures as well as the amounts of sulphuric acid present in 

 different series. 1 It will be seen that, while there is consider- 

 able variation between individual determinations, these vari- 

 ations are no greater between analogous samples of two cor- 

 responding series than between two succeeding samples of 

 the same series. Further, the means of the whole series agree 

 well with each other. The tables which I subjoin are selected, 

 solely with reference to their general reliability, from a larger 



1 In this connection it may be interesting to note that this reaction is, according to 

 my experiments, barely perceptible at 0C., a result which agrees closely with the 

 limit set by Dr. Hood by extrapolation with his temperature-coefficient. 



