Hydrogen and Nitrogen produced by a. Rays. 461 



quartz. There was, however, no sign of any activation in 

 either gas. This negative result is explained either by the 

 ultra-violet light not producing active gas, or by the quartz 

 not being sufficiently transparent to those rays which pro- 

 duce the active modification. 



The amount of gas absorbed was independent of the 

 thickness of the element deposited on the glass surface : this 

 indicates that the chemical action occurs at the surface. 



The rate of absorption was increased by using a larger 

 surface area of polonium, and was decreased when the 

 temperature of the gas was raised. The activation of the 

 gases thus appears to become greater as the temperature is- 

 lowered. 



6. Discussion of Results. 



Langmuir * found that hydrogen and nitrogen at low 

 pressures disappeared in the presence of an incandescent 

 tungsten filament, ^md he has utilized this fact in the elimi- 

 nation of the last traces of gas in valves, etc. The nitrogen 

 forms a nitride with the tungsten. He accounted for the 

 disappearance of the hydrogen by assuming that the mole- 

 cules of the gas on impact with the hot filament are disso- 

 ciated into atoms, and these atoms, at very low pressures, 

 have a clear run to the walls of the vessel, and condense on 

 them. This disappearance is marked at low temperatures* 

 On heating the tube, Langmuir found that part of the gas 

 was recovered. This re-liberated gas he supposes is due 

 to the re-combination of the atoms driven off from the walls 

 of the vessel by the heat. 



At the pressures used in the present work, it is unlikely 

 that the active gas consists of atoms. It is probably dis- 

 sociated at first into atoms by the action of the a rays, and 

 the atoms then unite with neutral molecules to form tri- 

 atomic molecules. The existence of these triatomic forms of 

 nitrogen and hydrogen has been shown by Wendt, in the 

 papers previously quoted, by passing electric discharges 

 through these gases at low pressures. 



The function of the ions produced by the a rays does not 

 appear to assist a chemical action between the gas and the 

 element which does not otherwise take place, for the com- 

 bination occurs after the ions have been removed. More 

 probably the activity of the gas is due to an atomizing effect 

 of the a rays on the gas, the active product being monatomic 



* Amer. Cbem. Soc. Journ. xxxv. (1913) ; & xxxvii. (1915). 



