Carbon and Oxygen in the Sun. 451 



sured with different lengths of arc. Table I. gives the 

 results for pure carbon ; Table II. for 28 per cent, of iron 

 and 72 per cent, of carbon. 



Length of Arc 

 in millims. 

 1 



Table I. 



Amperes. 

 27 



Volts, 

 25 



2 



23 



24 



3 



22-5 



20 



4 



20 



18 



5 



16-5 



15 



Length of Arc 

 in millims. 

 1 



Table II. 



Amperes. 



30-5 



Volts. 



30 



2 





30 



3 



27-5 



28 



4 



24 



25 



5 



22 



20 



6 



20 



20 



7 



18 



19 



8 



16 



18 



The length of the arc could be nearly doubled with the 

 same current and the same voltage by the admixture of 28 per 

 cent, of iron. The light was apparently greatly increased, 

 but the difference in colour between the pure carbon light 

 and the iron-carbon light made measurements unreliable. 



Moissan* has shown that the carbon in an electric oven 

 through which powerful electric currents have flowed is free 

 from foreign admixtures. Deslandres has confirmed this, 

 and finds only a trace of calcium present. The self purification 

 comes from a species of distillation of the volatile imparities. 

 The purest carbon is found at the negative pole. The 

 light of the electric furnace is due to the combustion of 

 carbon. Can we conclude that the sun is a vast electric 

 furnace ? 



If the voltaic arc is formed in rarefied air or under water, its 



* Comptes Bendus, cxx. pp. 1259-1260 (1895). 

 212 



