its place in the Classification of Elementary Substances. 7 



gases producing these lines. Lockyer has indicated in 

 several papers* that the new gas obtained from uraninite 

 by his distillation method is a mixture, and that some of 

 the spectral lines common to the chromospheric and terres- 

 trial gas may belong to two or more elementary substances. 

 Professors Runge and Paschen have made further progress 

 in this direction by showing that the gas from cleveite, after 

 being diffused through asbestos, gives two different spectra, 

 and is, consequently, a mixture. t One of these gases, from 

 its more rapid diffusion, is considered to be less dense than 

 the other. From a comparison of these spectra, the 

 German physicists further conclude that the denser of the 

 two gases, producing D 3 is helium proper, but the lighter 

 constituent has not yet received a name. 



It may be of interest for me to note here that, when a 

 strong induction-current is transmitted for a few minutes 

 through a newly-filled vacuum-tube of reputed helium, the 

 red line 7066 disappears entirely from the spectrum, and 

 all subsequent differences in the intensity of the discharge 

 fail to reproduce it. 



In my classification of elementary substances in multiple 

 proportions of their atomic weights, each series or family 

 is considered to be condensations of the typical elements, 

 H, H2, H3, H4, H5, H6, H7.J That some, if not all, of 

 these elements exist in a gaseous condition, and are of 

 small specific gravity, appears to me to be highly probable. 

 M. Langlet, of the University of Upsala, has found the 

 density of the cleveite gas to be 2*02 (H = i);§ while the 

 more recent determination of Ramsay has raised the density 

 of reputed helium to 2*13. Should, however, the conclu- 



* Pyoc. Roy. Soc, April 25, May 9, June 13, 1895. 



t Paper read before the British Association at Ipswich ; Nature, 

 September 26, 1895. 



I Memoirs Manch. Lit. and Phil. Soc, 1878, 1887, 1895. Chem. News,. 

 Vol. XXXVIII., pp. 66, 96, 107. 



§ Comptes Rendus, June 4, 1895. Chem. Soc. Journal, June 20, 1895. 



