352 THE CHEMISTRY OF THE SUN. [CHAP. 



That will give an idea of the way in which we really do find the 

 laboratory work and the observatory work each coming to the 

 rescue of the other, each helping us to understand some- 

 thing which, without the other record, would be excessively 

 difficult ; and how the results, strange and apparently anomalous 

 according to the old view, obtained with regard to the thick- 

 ness of the lines are exactly matched by equally anomalous 

 results when we consider the changes of refrangibility. 



Professor Young in referring to this part of the work writes 

 as follows : 1 



" In the motion-distortions of lines Lockyer finds strong con- 

 firmation of his ideas. It not unfrequently happens that in the 

 neighbourhood of a spot certain of the lines which we recognise as 

 belonging to the spectrum of iron give evidence of violent motion, 

 while close to them, other lines, equally characteristic of the 

 laboratory spectrum of iron, show no disturbance at all. If we 

 admit that what we call the spectrum of iron is really formed in 

 our experiments by the super-position of two or more spectra 

 belonging to its constituents, and that on the sun these constituents 

 are for the most part restricted to different regions of widely 

 varying pressure, temperature and elevation, it becomes easy to see 

 how one set of the lines may be affected without the other. The 

 same facts are of course also explicable on the supposition that 

 there are several allotropic forms of iron-vapour, mixed together in 

 terrestrial experiments but separated on the sun, and sorted out, so 

 to speak, by the conditions of temperature and pressure." 



With regard to the latter part of the paragraph, I may add 

 that if it had been a fact generally accepted by chemists, " that 

 there are several allotropic forms of iron -vapour, mixed together 

 in terrestrial experiments but separated on the sun," a great 

 part of this book need never have been written. 



Messrs. Liveing and Dewar are more bold, they deny that the 

 prominence member of the triplet is iron at all. 



1 The Sun, page 100. 



