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LVII. Conductance produced in Gases by Rontgen Rays, by 

 Ultra- Violet Light, and by Uranium, and some consequences 

 thereof. By J. Carkuthees Beattie, D.Sc, F.R.S.F., 

 1851 Exhibition Scholar, Research Fellow of the University 

 of Glasgow, and M. Smoluchowski de Smolan, Ph.D., 

 Research Fellow of the University of Glasgow *. 



§ 1. %17E propose in the following paper to give the results 

 TT of experiments carried out by us at Lord Kelvin's 

 suggestion, and with his help, in the Glasgow University 

 Physical Laboratory. We shall give first results which relate 

 to the conductance produced in gases by Rontgen rays, by 

 ultra-violet light, and by uranium. Secondly, results bearing 

 on the quasi-conductance produced in solid dielectrics by 

 Rontgen rays. Thirdly, we shall give an account of experi- 

 ments which we made to measure the difference of potential 

 between wires of the same metal connected metallically 

 with two plates of any two metals between which Rontgen 

 rays, ultra-violet light, or " uranium rays " pass. 



§ 2. On the Conductance produced in Air, at ordinary 

 pressure and at different voltages, by Rontgen rays, by 

 uranium, and by ultra-violet light. 



To measure the conductance produced in air by Rontgen 

 rays and by uranium, we used an arrangement consisting of 

 two quasi leyden-jars, A and B, with their inside coatings 

 connected together. The outside coating of A was connected 

 to the case of a quadrant electrometer, the outside coating of 

 B, which was insulated on a block of paraffin, to the insulated 

 terminal of the electrometer (see fig. 1). 



In all the experiments in which the two-leydens arrange- 

 ment was used the leyden B remained the same. It con- 

 sisted of a cylindrical lead can, 25 centim. long, 4 centim. 

 diameter. A metal bar about 1 centim. diameter, 25 centim. 

 long, was supported centrally on parafhn filling the whole 

 space between the metal bar and the containing lead. The 

 metal bar was connected by a wire to the internal coating 

 of A. To protect this wire from inductive effects it was sur- 

 rounded by a tube of lead connected to the case of the 

 electrometer. 



In the experiment with Rontgen rays the leyden A con- 



* Communicated by Lord Kelvin, having been read before the 

 Glasgow Philosophical Society, April 14th, 1897. The chief results 

 were described in several papers communicated to the Royal Society of 

 Edinburgh since the beginning of the present year. 



