180 



THE CHEMISTHY OF THE SUN. 



[CHAP. 



The accompanying diagram (Fig 71) of the fluted spectrum of 

 iodine will show the difference between these fluted spectra and 

 the line spectra on which we have been exclusively occupied up 

 to the present. 



We observe that the chief novelty is an absolute rhythm in 

 the spectrum ; instead of lines irregularly distributed over the 



on: 



FIG. 71. Fluted spectrum of iodine. (Thalen.) 



spectrum, we have groups which are beautifully regular in their 

 structure. The next diagram (Fig 72) shows us the radiation 

 spectrum of a particular molecular grouping of carbon vapour ; 

 that also is beautifully rhythmic, the rhythm of each of the 

 elementary flutings strongly resembling that of iodine. 



FIG 72. Carbon flutings. 



These observations were among the first to suggest the idea 

 that the same chemical element could have two completely dis- 

 tinct spectra. They were eminently suggestive, for if two, why 

 not many ? 



In the reference to the " long and short " method of observation 

 it was stated that it enabled us to note what happens when a 



