60 Mr. J. Norman Lockyer. On the Appearance of the 



Lines other than Hydrogen and Cleveite Gases which make their 

 appearance only at Temperatures higher than a Cygni, or become 

 intensified at higher Temperatures. 



"Wave-length. 



a Cygni. 



Eigel. 



Bellatrix. 



£ Orionis. 



3919 '2 



— 



— 



3 



— 



3994 -7 



— 



2 



5 



3 



4010 "6 



— 



— 



3 



— 



4069 '7 



— 



— 



3 



3 



4071 *7 



— 



— 



3 



— 



4075 "7 



— 



— 



3 



3 



4088 '7 



— 



— 



— 



8 



4094 '7 



— 



— 



! , 



3 



4104 *8 



— 



— 



3 



— 



4114 *8 



— 



— 



— 



7 



4172 -6 







2 





4253 *6 



. — 





3 





4267 * 6 





3 



/ 



2 



4314 -6 









2 



4345 '6 







3 





4415-2 







3 



2 



4541 -8 









2 



4566 -8 







3 





4574-8 







3 





4613 -8 







3 





4643 -8 







3 





4650 -9 







3 



10 



intensification of lines in the hottest stars in passing from a Cygni is 

 a trustworthy criterion for gaseous lines. 



If there are other gases which, like hydrogen, give indications of 

 their presence at the temperature of cc Cygni, or lower, the lines in the 

 spectrum do not, like those of hydrogen, become more intense with 

 increased stellar temperature. In such cases it does not seem 

 likely that anything short of the actual discovery of terrestrial 

 sources of the gases can help us to differentiate the lines belonging to 

 them in stellar spectra from those due to metallic substances. 



Attempts to trace Terrestrial Sources of the New Gases. — In a series 

 of papers communicated to the Royal Society I have given an account 

 of the attempts which I have made to find new gases by experi- 

 ments upon minerals similar to those adopted for the extraction of 

 helium and the associated gases from cleveite. In the last paper of 

 that series I summarised the results which had been obtained, indi- 

 cating that lines occurring in the spectra of gases from minerals for 

 which no known origin could be assigned were represented in the 

 spectra of some of the hotter stars.* 



From this I extract the following list of the lines thus found to- 



* ' Eoj. Soc. Proc.,' vol. 60, p. 333. 



