INFLUENCED BY RADIUM. CREIGHTON. 37 



The Action of Radium on Hydrogen Peroxide. 



The action of radium on hydrogen peroxide was next inves- 

 tigated, as on account of its behaviour under the influence of 

 light/ it was believed that it would be affected by radium rays. 



The hydrogen peroxide solution used in these experiments 

 had a strength of 4.832 grams per litre. 



Since hydrogen peroxide, when it decomposes, breaks up 

 into water and oxygen, its decomposition can be estimated by 

 measuring the oxygen produced, or the amount of hydrogen 

 peroxide left in the solution by titrating with potassium per- 

 manganate. As this latter method necessitated changing the 

 amount of substance in the system, the former was chosen, and 

 the oxygen was measured by the change of pressure it produced. 



A large reagent bottle, with a side tubulature near the bot- 

 tom, was half-filled with hydrogen peroxide. Into the side neck 

 was fitted a long graduated tube with a bend at right angles, 

 which was to act as a pressure gauge. The brass tube contain- 

 ing the radium was passed through a tightly-fitting' rubber cork, 

 which was fixed firmly into the neck of the reagent bottle and 

 so adjusted, that the radium was about three or four millimetres 

 away from the surface of the liquid. In this way, any increase 

 in the volume of the gas over the peroxide would produce a 

 change in its pressure, and this change could be read by means 

 of the pressure gauge. Figure 2 shows the apparatus. 



These experiments were carried out in a photographic dark- 

 room, so that there was no chance of the reaction being 

 influenced by light. 



D'Arcy, Phil. Mag., 1902 [VI]. 3, 42. 



