VIII. 



RECENT OPINION. 77 



that the intense he;it of the sun carries the process of molecular 

 simplification much farther; and, if we compare the complicated 

 spectra of the vapours of metals produced by the highest tempera- 

 tures available here with the very simple spectra of the same metals 

 as they exist in the hottest part of the sun's atmosphere, it is diffi- 

 cult to resist the conclusion that the atom of the chemiit has itself 

 been changed. My own belief is that these ' atoms ' are changed, 

 and that iron, as it exists in the sun, is not the vapour of iron as we 

 know it upon earth."* 



.The Basic Lines. 



With regard to the basic line part of the inquiry, I think I shall 

 tiot be going too far in saying that it has been universally rejected, 

 .and chiefly on the ground that some lines which appeared coincident 

 at the dispersion I employed appeared double with higher disper- 

 sions. I have pointed out in the Chemistry of the Sun (p. 377) 

 that this is not a sufficient answer, but I have left aside this branch 

 of the inquiry for some years in the hope that some chemist would 

 take up the question of spectroscopic impurities out of which it grew. 

 But it is evident that this basic line point of view, even though it 

 be considered a less direct attack on the problem than others since 

 begun, assumes a much more important and definite position in the light 

 of the new work. I will not go into this question at length now, but 

 will content myself here by asking whether one actual demonstration 

 of dissociation will not take a form very like that which the chemist 

 has taken to be a proof of the existence of impurities. 



I shall return to this later on. 



Other Physical Researches now in progress. \ 



So much for opinion a year or two ago. In subsequent chapters I 

 shall refer to other attacks upon the problem of dissociation, which to 

 my mind and to many of the objectors sets the matter on a much 

 firmer basis by accumulating facts, not only with regard to the stars, 

 but in other fields of inquiry in which the idea of dissociation has to 

 be appealed to in order to explain the phenomena. 



* Proc. Roy. In<f., vol. xiii, p. 509, 1892. 



