Cleveite and other new Gas Lines in the Hottest Stars. 61 



have probable counterparts in the hotter stars, and show the inten- 

 sities in different stars. Lines which have since been found to 

 correspond with enhanced lines in the spectra of any of the sub- 

 stances so far examined are omitted. 



Stellar Lines probably coincident with Lines in the Spectra of Gases 

 from various Minerals. 



"Ware-length. 



a Cygni. 

 Max. = 10. 



Eigel. 

 Max. = 10. 



Bellatrix. 

 Max. = 10. 



5 Ononis. 

 Max. = 10. 



3929 -4 









1 



3961 6 



3 









4002 -9 



5 









4069 -7 







3 



~3 



4072 *2 



1 





3 





4114-6 









7 



4309 -4 



1 









4338 -0 



5 









The lines thus observed in the spectra of mineral gases may be 

 divided into two groups, the first comprising those which are 

 strongest in a. Cygni and thin out at higher temperatures, and the 

 second those which are either absent from a. Cygni or become 

 stronger as the temperature of oc Cygni is exceeded. The lines of 

 the first group behave like the enhanced lines of the metals, and, 

 unless the gases can be isolated, it is impossible to say whether the 

 corresponding stellar lines are produced by gases or the coincidences 

 are merely accidental. 



In the case ot the second group of lines, however, the probability 

 that the mineral gases which give them really represent new lines is 

 much greater, since, like the lines of helium, they are most intense 

 in the stars which we have every reason to believe to be the hottest. 



Attempts to Trace Series of Lines. — A minute examination of 

 Bellatrix has been made by Dr. W. J. S. Lockyer with a view of 

 inquiring whether some of the many still unknown lines might 

 possibly form series like those of helium and asterium. 



With this object the lines in the spectrum were carefully plotted, 

 special attention being given to the intensities of the individual lines. 

 An examination of the residual spectrum formed by omitting all 

 those lines the origins of which were known, showed that possibly 

 two further series were present, but a better photograph of the star 

 spectrum is required to settle the matter definitely. 



The residual lines in the spectrum of Bellatrix in the existing 

 photographs after hydrogen, helium, and asterium have been with- 



