10 



INORGANIC EVOLUTION. 



[CHAP. 



chemistry ; the spectrum varies according to the chemical substance 

 which produces it in a manner that will be gathered from an inspec- 

 tion of the photograph (Fig. 8) which shows the difference between the 

 spectrum of barium (A), and that of iron (B). 



Flutings. 



The earliest spectroscope observations revealed the fact that in some 

 spectra the lines, instead of being irregularly distributed along the 

 spectrum, were arranged in an easily seen rhythmic fashion. Such 

 allocations of lines are called flutings, as a succession of them gives 

 rise to an appearance strongly recalling the flutings of a Corinthian 

 column seen under a strong side light. 



FlG. 9. Fluting of carbon. 



Our improvised spectroscope helps us here too ; use the candle and 

 straight slit in front of it as before, but shorten the slit, and only 

 allow the blue light from the base of the candle flame to pass through 

 it to the prism. We see two or three sets of flutings. These are the 

 flutings of carbon; they are amongst the most beautiful examples 

 known and are thoroughly typical. 



FIG. 10. Flutins: O f magnesium. 



Series. 



One of the most important discoveries made in recent years, teaches 

 us that in the case of many chemical elements, the apparently irregular 

 distribution of the lines is really dominated by a most beautiful law, 

 and that the most exquisite orderly rhythm can be obtained by sorting 



