The Existence of Uranium Y. 215 



where the symbols refer to the values for unit length of the 

 line. If R = 0, this reduces to 



4 = lo 



(a/ 1 +S+ 1 > 



from which it is seen that any increase in the leakage $ 

 causes a decrease in the velocity. 



Now the results published by Prof. Barton and Mr. Kilby 

 show agreement with the ordinary theory of the leaky 

 condenser, and therefore indicate that the condenser with a 

 dielectric of ionized air at atmospheric pressure had that 

 type of conductivity or leakage which cannot cause an 

 increase in the velocity of propagation, but can only cause 

 a decrease of velocity and a certain amount of dissipative 

 absorption. 



The statement that " the work yields some experimental 

 support to the theory of Dr. Eccles " appears therefore to be 

 unjustified. 



It would appear necessary to repeat the experiments with 

 various vacua in the vessel containing the air condenser 

 before the results could have any bearing on the theory put 

 forward by Dr. Eccles. 



XXII. The Existence of Uranium Y. 

 By Frederick Soddy, M.A., F.R.S.* 



[Plate II.] 



GN. ANTONOFF (Phil. Mag. 1913 [6] xxvi. p. 1058) 

 • states that he has been able to repeat his experiments, 

 which led him two years ago to conclude that a new product, 

 uranium Y, of half-period 1*5 days, existed in the uranium 

 series, with some purified uranyl nitrate obtained from me, 

 and with which A. Fleck in this laboratory (Phil. Mag. 1913 

 [6] xxv. p. 710) was unable to obtain the same effects. I 

 have pleasure in being able to confirm AntonorPs main 

 result of an abnormal decay of the soft /3-rays of uranium X, 

 also with some of the same material. 1 approached the 

 subject from a point of view which it seemed might account 

 for the discrepancy between the two experimenters. It 

 appeared possible that Antonoff's uranium Y might be 

 isotopic t with uranium X, and that any chemical operation 



* Communicated by the Author. 



t The terms " isotopic elements " or " isotopes " are convenient to indi- 

 cate elements occupying - the same place in the periodic table and there- 

 fore chemically indistinguishable and non-separable. See ' Nature.' 

 December 4th, 1913, p. 400. 



