460 Dr. F. H. Newman on Active Modifications of 



more hydrogen was drawn through. The experiment was 

 repeated without the polonium present, and in this case the 

 surface of the alloy remained quite clear. The film produced 

 is due to chemical action of the active hydrogen on the alloy. 

 The white crystalline compound appears to be a mixture of 

 the hydrides of sodium and potassium, while the bluish-grey 

 coloured product afterwards formed is probably a solution 

 of these hydrides in the alloy. 



Fig. 2. 



x 

 HYDROGEN 



PUMP 



For the investigation of sulphur, a film of this element 

 was deposited over the interior surface of C by distillation in 

 vacuum. D contained some filter-paper soaked in lead- 

 acetate solution, together with a little of the solution. After 

 hydrogen, subject to the action of the a rays, had been drawn 

 over the sulphur for about 30 minutes, the filter-paper in D 

 became blackened. This indicated the presence of hydrogen 

 sulphide in the stream of gas, and it had been produced by 

 the action of the active hydrogen on the sulphur. A similar 

 result has been found by Wendt and Landauer *. This 

 chemical action is not due directly to the ions present in the 

 gas, for they are all removed by the electrostatic field before 

 coming into contact with the sulphur. 



5. Other Experiments. 



Some radium emanation of strength 57 mg., enclosed in a 

 glass tube, was substituted for the polonium. The thickness 

 of the glass — about 0'5 mm. — absorbed the a rays but trans- 

 mitted the other rays. After several hours of test there 

 was practically no absorption of hydrogen or nitrogen by 

 any element : this indicates that the a rays are the effective 

 ones in the chemical actions observed above. 



Ultra-violet light was employed instead of the radio- 

 active compound. A quartz-mercury lamp was used as the 

 source of illumination, and the experimental bulb A was of 



* Amer, Chem. Soc. Journ. xlii, (1920). 



