i873«] Colours and their Relations. 75 



of their regulating laws, have been indicated in a previous 

 essay, entitled " Molecules, Ultimates, Atoms, and Waves," 

 which appeared in the " Quarterly Journal of Science," 

 vol. i. N.s., p. 170, in April, 1871, and the two following 

 numbers. In that essay reasons were adduced for concluding 

 that the bright coloured lines observed in the spectra of glow- 

 ing gases are due not to the vibrations of the ultimates of the 

 gases themselves, but to those of more minute atoms con- 

 stituting those ultimates. More especially in the case of 

 hydrogen, it was shown to be probable that the ultimate of 

 that gas consists of four species of extremely minute atoms, 

 whose separate vibrations produce the four bright lines 

 which characterise the spectrum of that gas when made to 

 glow by passing through it an electrical discharge. 



These views, respecting the constitution of hydrogen and 

 the other chemical elements, have received a remarkable 

 confirmation in certain phenomena observed by the spectro- 

 scope in the solar chromosphere. When viewed with that 

 instrument, the chromosphere usually presents the four 

 lines characteristic of hydrogen, and two other lines — one 

 in the yellow, not coincident with the sodium lines, nor with 

 any other produced by any known terrestrial substance, and 

 denoted as D 3 — the other in the red, a little less refrangible 

 than C, and in like manner not referable to any known sub- 

 stance. Now, in two observations — one by Mr. Lockyer, 

 the other by Professor Young (the latter made on 19th April, 

 1870), the line F, supposed to be due to hydrogen, was 

 agitated in a remarkable manner, indicating that the sub- 

 stance in which this line has its origin was in a state of 

 violent commotion ; but on both occasions the red line C, 

 also supposed to be due to hydrogen, remained totally un- 

 affected. 



Of this remarkable phenomenon the most simple explana- 

 tion would be to suppose that, in the chromosphere, the 

 four atoms constituting the ultimate of hydrogen exist dis- 

 united, forming four distinct gases more subtle than hydro- 

 gen ; that of these gases, the one producing the line F was, 

 during the observations in question, ascending in a gyratory 

 column, while the one producing the line C was at rest. 



A similar conclusion may be drawn from other spectro- 

 scopic observations of the solar limb, in which certain of the 

 dark lines of the spectrum become converted into bright 

 lines. It is remarkable that only a certain number of the 

 lines due to particular metals have been thus affected — more 

 especially three of the lines referred to magnesium, and only 

 one or two of the numerous lines referred to iron. The lines 



