186 



Sir Norman Lockyer. 



EXPLANATION OF PLATE. 



A and B. Spectrum of a hydrogen vacuum-tube from which the reference lines, 

 F, G-', h, and H x are obtained, with the potassium Kp line thrown in. The 

 solar lines, L, M, N, and P are obtained by measurement from a negative of 

 the solar spectrum. 



Fig. 1. Crude chlorophyll in alcohol. 

 „ 2. „ ,, ,, diluted. 



3. Xanthophyll from crude chlorophyll solutions in alcohol by the action of 

 animal charcoal. 



4. Xanthophyll from faded autumnal yellow leaves in alcohol. 

 ,, 5. Chrysophyll in alcohol. 



,, 6. Crude chlorophyll in alcohol. 



„ 7. „ „ ether. 



„ 8. ,, „ alcohol diluted. 



„ 9. „ » ether „ 



; , 10. Xanthophyll in alcohol. 



„ 11. „ ether. 



" On the Chemical Classification of the Stars." By Sir Norman 

 Lockyer, K.C.B., F.K.S. Eeceived April 27 —Bead May 4, 

 1899. 



[Plate 7.] 



In the attempts made to classify the stars by means of their spectra, 

 from Bntherford's time to quite recently, the various criteria selected 

 were necessarily for the most part of unknown origin ; with the excep- 

 tion of hydrogen, calcium, iron, and carbon, in the main chemical 

 origins could not be assigned with certainty to the spectral lines. 

 Hence the various groups defined by the behaviour of unknown lines 

 were referred to by numbers, and as the views of those employed in 

 the work of classifying differed widely as to the sequence of the 

 phenomena observed, the numerical sequences vary very considerably so 

 that any co-ordination becomes difficult and confusing. 



Recent work has thrown such a flood of light on the chemistry of * 

 the stars that most definite chemical groupings can now be established, 

 and the object of the present communication is to suggest a general 

 scheme of classification in which they are employed, in relation to the 

 line of cosmical evolution which I have developed in former papers 

 communicated to the Society. 



The fact that most of the important lines in the photographic region 

 of the stellar spectra have now been traced to their origins renders 

 this step desirable, although many of the chemical elements still remain 

 to be completely investigated from the stellar point of view. 



The scheme is based upon a minute inquiry into the varying inten- 

 sities, in the different stars, of the lines and flutings of the under- 

 mentioned substances : — 



