710 Mr. A. Fleck on the 



atmospheric pressure. To this end the plate covering the 

 end of the tube T 2 nearest to the sender S was removed, 

 and the radium in an open glass dish, a crystallizing dish, 

 was alternately put in and taken out of the tube, and the 

 deflexions observed in both cases. No difference in the 

 deflexion for the two cases was found except that which was 

 due to the presence of the glass dish itself. It was found 

 that the dish itself obstructed the waves to a certain extent. 



Summary. 



The results show that for electric waves about 10 cm. long 

 passing through air at pressures ranging from 76 cm. to 

 *001 cm. of mercury, and through water- vapour at pressures 

 ranging from 1'50 cm. to *015 cm,, the absorption of the 

 energy of the waves by the air, if it exists, must be less than 

 one-tonth of one per cent, per centimetre. 



This was also found to be true when the air was ionized 

 by radium chloride placed in open vessels within the tube. 

 This would indicate that the ionization of the air by radium 

 produces, if any, only a very small effect upon its absorbing- 

 power for electric waves about 10 centimetres long. 



In conclusion, I wish to acknowledge the great aid 

 received in this research from a grant from the Bache Fund 

 of the National Academy of Sciences for the purchase oE 

 apparatus. 



University of Cincinnati, 

 May 1912. 



LXXIII. The Existence of Uranium Y. 

 Bu Alexander Fleck, B.Sc* 



fTlHE only direct disintegration product of uranium that 

 JL is actually known is uranium X, but Antonoff'f described 

 some experiments which, he thinks, show the existence of 

 a new substance. As it is present in exceptionally small 

 quantities he concludes that it is a branch product whose 

 parent is uranium. The work, of which a short description 

 is given below, was undertaken to attempt to confirm the 

 existence of this new body. 



Uranyl nitrate, which was known to have contained 

 thorium but which was thought to have been purified by 

 treating twice with excess of ammonium carbonate, was 

 employed to repeat AntonofFs experiments as nearly as 



* Communicated bv F. Soddv, F.K.S. 



t Antonoff, Phil. !\Iag\ [6] xxii.p, 431 (1911). 



