THE SPEED OF REDUCTIONS 317 



be obtained by mixing cerium sulphates and glucose in equi- 

 molecular amounts in dilute solution, maintaining at 25 C., 

 and titrating samples with very dilute hydrogen dioxide solu- 

 tion, which instantaneously completes the decolorization of 

 the eerie salt. The reaction with glucose is completed in about 

 two hours and can be readily followed in 15-minute intervals. 

 Of course, the stability of the hydrogen peroxide standard 

 was meanwhile controlled with permanganate solution. 



For some unexplained reason, the reaction as studied by 

 me does not follow a logarithmic law: the amount of cerium 

 reduced is simply proportionate to the elapsed time, so that 

 x/t is pretty nearly constant for every individual series. So 

 anomalous a [604] behavior naturally precludes any claim 

 on rigid deduction. But the experiments had comparative 

 values, when they were compared with others, in which equiv- 

 alent quantities of lanthanum sulphate and thorium sulphate 

 had been mixed with the solution of cerium salts. 



Values of x/Wt 



Pure eerie solution 694.8,693.1, 



With thorium 708,697 



With lanthanum 665.1,658.1 



Here again, the influence of the cognate metal seems un- 

 mistakable and distinctive. My only explanation lies in the 

 complexity of the base, although I admit that the evidence, 

 so far, is not conclusive. 



