58 THE CHEMISTRY OF THE SUN. [CHAP. 



It has been necessary in dealing with this, so to speak, crucial 

 epoch in the history of our subject to give as far as possible the 

 ipsissima verla of the workers whose genius we have to thank 

 for a series of researches which has not only enabled us to study 

 the chemistry of the sun, but has given us as its first tremendous 

 outcome the conclusion that the sun and earth have the same 

 chemical constituents. Where some, at all events, might have 

 anticipated a new world of matter, we find likeness to the old. 



With regard to this conclusion it is not too early to make 

 the following remarks on the views concerning the chemical 

 elements held when the spectroscope was introduced. 



That instrument placed us in presence of phenomena pro- 

 duced by higher temperatures than had ever been employed 

 before. The elements either did or did not bear that tempera- 

 ture without dissociation, and the spectra observed were, 

 therefore, either the spectra of the elements themselves, or of 

 their constituents. 



Similarly the sun must either give us the spectra of the 

 elements contained in it or the spectra of their constituents. 



The similarity, therefore, of solar and terrestrial spectra, even 

 if established, cannot be regarded as a final argument in favour 

 of the elementary nature of the bodies which Lavoisier had 

 considered elemental. This point, in fact, was never, so far as I 

 know, raised. 



On this subject I am permitted to print a memorandum 

 which has been given to me by my friend, Dr. Hodgkinson : 



The great point in Lavoisier's teaching, affecting the chemistry of 

 his and our own time, was the recognition of the compound nature 

 of some bodies, and the so-called simple nature of others ; and that 

 these compounds can be reduced to the simple state, or elemental 

 condition, of matter. 



The history of chemistry is one of a development of ideas and 

 theories, more so than in any other science ; a given theory or idea 



