82 Proceedings of the Royal Irish Academy. 



Mohilities in Hydrogen. 



Haines,' working with pure and freshly prepared hydrogen, found that 

 in addition to free electrons there were present a number of groups of 

 negative ions of mobilities higher than the normal. As the gas became 

 contaminated by remaining in the apparatus these ions gi-adually disappeared. 

 Eesults suggestive of abnormal mobilities for negative ions in hydrogen have 

 also been obtained by Latter and Tizard- and by Chattock and Tyndall.^ 

 On the other hand, Kia-Lok Yen* has endeavoured to repeat Haines' 

 experiments without success. 



In pure hydrogen Haines found that the positive ion had a mobility value 

 of 54:, and that this value was constant. He distinguishes three main classes 

 of negative ions : Class A, mobility 7"9, Class B, mobility 15'9, and Class C, 

 mobility 40'6. In addition he finds subordinate classes of mobilities 9'2 and 

 19-6. These results are very much on the lines of tliose obtained by the 

 author for air. Parity in the hydrogen seems to play the same part as 

 dryness in the air in bringing out the high mobilities. Certain differences 

 remain. At no time does Haines find the positive ion to be of a composite 

 character, nor does he find the negative ion composite under normal 

 conditions. It seemed important therefore to make a close examination of 

 the ions in hydrogen under normal conditions, and then under such conditions 

 of purity and dryness as could be readily attained. 



Hxperiments on Hydrogen not specially dried. 



The apparatus and method of working need only be treated of briefly 

 here. Ions were produced in the space above a sheet of brass gauze of fine 

 mesh. This gauze was supported on ebonite pillars exactly 4 cms. above an 

 insulated plate furnished with an earthed guard-ring. The plate was 

 connected to the Dolezalek electrometer used for the current readings. The 

 source of ionization was, as in the previous work, polonium. The ions were 

 exposed to an accelerating field, generally about 10 volts per cm., so that 

 those of the sign under examination were caused to diffuse through the 

 gauze. The alternating voltage applied to the gauze was read off directly on 

 an Ayrton and Mather electrostatic voltmeter. Two of the latter were used, 

 covering different ranges. The hydrogen was generated in a Kipp's apparatus 

 from HjSO^ and granulated zinc, passed through lead nitrate and silver 



1 Haines, Phil. Mag., Oct., 1915, and April, 1916. 

 - Lattey and Tizard, Proc. Royal Soc, 1912, p. 349. 

 3 Chattock and Tyndall, Phil. Mag., 1910. 

 * Kia-Lok Yen, Physical Review, xi, 1918. 



