Modifications of Hydrogen and Nitrogen by a Mays. 455 



which had then commenced also made the temperature con- 

 ditions in the tubes very unfavourable for systematic work. 

 Nevertheless, on two evenings when observations were made 

 after a smart shower following an April nor'wester, the 

 fringes were seen very steadily, and appeared to show a slight 

 but unmistakeable shift on reversing the direction of: the air- 

 current. On the second occasion an attempt was made to 

 estimate the magnitude of the shift by setting a cross wire 

 on the fringes and comparing the shift observed on reversing 

 the air-current with that produced by flexure of the micro- 

 scope tube by a known small load. The shift was estimated 

 to he about ^ part of a fringe, which was of the right 

 order of magnitude and in the direction indicated by theory. 

 Subsequent attempts to confirm these observations and 

 measurements under less favourable conditions proved un- 

 fruitful, as the fringes then showed a distinct rotation as a 

 whole when the air-current was reversed. The rotation 

 proved to be a verv troublesome and disturbing factor, and 

 before the cause of it could be ascertained and removed, the 

 work had to be suspended, owing to the departure of one of 

 us for Europe. While, therefore, the results so far obtained 

 cannot be regarded as entirely conclusive, they hold out a 

 distinct promise of success when the work is resumed under 

 more favourable conditions, particularly if a more powerful 

 blower with steady electric drive can be obtained and 

 installed. 



L. Active Modifications of Hydrogen and Nitrogen produced 

 by a Rays. By F. EL Newman, M.Sc, Ph.D., Head of 

 the Physics Department, University College, Exeter *. 



1. Introduction. 



IT has been shown recently t that nitrogen and hydrogen 

 are both absorbed in the electric discharge tube, in the 

 presence of various elements, when an electric discharge 

 passes through the gases. This effect is due, in part, to 

 chemical action, and is greatest when the element under 

 investigation is deposited on the cathode of the tube. The 

 chemieal action appears to be produced by the gases 

 assuming active modifications when an electric discharge is 



* Communicated by the Author. 



t Newman, Proc. Phys. Soc. xxxiii. part ii. (1921). 



