200 THE CHEMISTRY OF THE SUN. [CHAP. 



probable that this higher temperature had done for the matter 

 on which they had experimented exactly what all lower tem- 

 peratures had been found to do? that is to say, broken the 

 matter up. In other words, when we subjected, say iron, to 

 one of these transcendental temperatures, we were possibly 

 110 longer dealing with the spectrum of iron itself, but with 

 the spectrum of the constituents of iron revealed^ to us by 

 a temperature at which no chemical experiments had been 

 made before. 



Indeed, if we appealed to facts, there were facts which 

 appeared to strengthen this view. The spectroscopic behaviour 

 of bodies known to be compound was known to us, and at 

 once suggested an explanation of many of the phenomena 

 which had been observed. Hence, then, there did seem to 

 be a way out of the difficulties which it w r as worth while to 

 consider. 



In a paper communicated to the Eoyal Society in 1873, deal- 

 ing, among other things, with the discovery of some new rnetals 

 in the solar atmosphere, I wrote as follows : 1 



I. The absorption of some elementary and compound gases is 

 limited to the most refrangible part of the spectrum when the gases 

 are rare, and creeps gradually into the visible violet part and finally 

 to the red end of the spectrum as the pressure is increased. 



II. Both the general and selective absorption of the photospheric 

 light are greater (and therefore the temperature of the photosphere 

 of the sun is higher) than has been supposed. 



III. The lines of compounds of a metal and iodine, bromine, &c. 

 are observed generally in the red end of the spectrum, and this 

 holds good for absorption in the case of aqueous vapour. 



Such spectra, like those of the metalloids are separated spectro- 

 scopically from those of the metallic elements by their columnar or 

 banded structure. 



..' TV. There are, in all probability, no compounds ordinarily 

 present in the sun's reversing layer. 



- 1 Bakerian Lecture, 1873 ; Phil. Trans, vol. clxiv. part 2, p. 491. 



