Hydrogen and Nitrogen produced, by ex. Rays. 459' 



ammonia test. Negative results were obtained with sulphur, 

 iodine, and phosphorus when tested for nitrides. The 

 absorption cannot be due to occlusion, otherwise the gas 

 would have been re-liberated on heating. The effect must 

 be due, in some cases at any rate, to chemical action. 



4. Experiments with Hydrogen. 



The gas was prepared by the electrolysis of barium hydrate. 

 After passing over sodium-potassium alloy to remove any 

 oxygen, and then over phosphorus pentoxide, it was stored 

 in a reservoir. Experiments were conducted in the same 

 manner as those with nitrogen, but it was found that the gas 

 was absorbed only by sulphur, phosphorus, ami iodine. The 

 results obtained are shown in Table II. The bulb was main- 

 tained at -40° C. 



Table II. 





Volume of hydroge 



n (at 760 mm. 

 in 30 mins. 



pr 



essure) absorbed 



Element, 



Pressure 

 5 mm. Hg. 



Pressure 

 101 mm. Hg. 





Pressure 

 299 mm. Hg. 



Sulphur 



0-09 c.c. 



o-io 



0-08 



0-13 c.c. 



0-16 



012 





0-46 c.c. 



Phosphorus 



Iodine 



049 

 0-43 







The rate of absorption decreased with time, and on heating 

 the bulb to 100° C. most of the hydrogen which had been 

 absorbed was re-liberated. This behaviour is different to that 

 in the case of nitrogen. This indicates that with hydrogen 

 the effect is either due to occlusion, or if it is due to chemical 

 action, the resulting compounds must be unstable. 



To show that the disappearance of the gas was due to 

 chemical action, the apparatus shown in fig. 2 was utilized. 

 Two strips of platinum foil, about 8 cm. long and fitting 

 close to the interior of the glass tube, were introduced at B. 

 The strips were connected to the terminals of a 600- volt 

 water battery. Any ions present in the gas were removed 

 as chey passed through B. Sodium-potassium alloy was 

 prepared in D, and, after the whole apparatus had been 

 exhausted, the alloy was run into C. As a result, the alloy 

 in C had a bright, clean surface. Hydrogen was then drawn 

 through the apparatus, and was subject to the action of the 

 a rays. When examined by a microscope, the surface at C 

 was seen to be covered with a white crystalline substance, 

 which afterwards changed into a blush-grey coloured film as 



