66 ORIGIN AND NATURE OF LIFE 



of iron would appear to indicate a position 

 with many unstable intermediate disruption 

 products of iron, which passes on by the 

 break-up of these into the small number 

 of stable products (under the given energy- 

 environment) represented by the small num- 

 ber of enhanced lines of the vacuum spark 

 spectrum. 



The next step in the chain of evidence 

 of the evolution of the elements is that when 

 the spectroscope is turned toward the sun 

 there most clearly seen are the important 

 enhanced iron lines of the vacuum- spark 

 spectrum, and no trace of the multitudinous 

 lines of the iron air-arc spectrum is to be seen. 

 What conclusion can be drawn save that iron 

 exists not merely as vapour in the sun, but as 

 vapour elementally decomposed to the stage 

 at which it is found in a vacuum spark- 

 break spanned by an electrical tension of a 

 hundred thousand volts ? 



There exists at present no form of thermo- 

 metry which will enable us to determine 

 whether the temperature in the actual spark 

 region is an enormous one, or whether the 

 transformations there shown by the spectro- 

 scope are directly electrical ones. Certainly 

 the bulb as a whole does not require a high 

 temperature. This point is an important one 



