424 Mr Fenton, On the decomposition of Hydrogen Dioxide 



The decomposition of Hydrogen Dioxide under the influence 

 of Radium Bromide. By H. J. H. Fenton, M.A., F.R.S., Christ's 

 College. 



[Bead 29 February 1904.] 



These experiments were originally undertaken with the object 

 of investigating the conditions which affect the stability of 

 solutions of hydrogen dioxide at the ordinary temperature in 

 absence of light. 



Pure hydrogen dioxide, prepared by distillation, is now obtain- 

 able from Merck of approximately ' 100 volume ' strength — 

 corresponding to about 30 per cent. H 2 2 , or nearly 10 times 

 ' molar' strength. This solution, which is sent out in bottles 

 coated internally with paraffin in order to avoid contact with 

 glass, keeps remarkably well in the dark ; a specimen which was 

 obtained about a year previously gave on analysis 28*9 per cent. 

 H 2 2 , or 8*5 times molar strength. But solutions prepared by 

 diluting this specimen with ordinary distilled water exhibited 

 very varying degrees of stability, and in some cases appeared 

 to be practically exhausted after keeping for a few weeks in 

 the dark. 



This instability cannot be attributed entirely to the direct 

 action of glass, since it appears also to a considerable degree in 

 paraffin-coated vessels, nor can it be ascribed to dilution which, 

 on theoretical grounds, would be expected to have an opposite 

 effect. Solutions prepared of very varying degrees of dilution 

 both with ordinary and ammonia-free distilled water, were con- 

 tained either in glass or paraffin-coated vessels and kept in the 

 dark under the same conditions. Analysis of corresponding 

 volumes of these solutions at definite periods shewed only very 

 slight differences compared with the total amount of change, 

 and the acceleration of the change must consequently be largely 

 due to the catalytic influence of some impurity, other than 

 ammonia, already present in the distilled water employed. 



During the progress of this enquiry Mr Hardy and Dr 

 Anderson most kindly supplied the loan of 50 milligrams of 

 radium bromide, and it was decided to extend the observations 

 in order to ascertain whether the rate of decomposition is ac- 

 celerated or otherwise influenced by the rays from this sub- 

 stance. 



Bredig and his colleagues in the course of an elaborate in- 

 vestigation have shewn that the rate of decomposition of hydrogen 

 dioxide under the catalytic influence of colloidal platinum and 



