R. Meldola—Bright Lines in the Solar Spectrum. 297 
metal breaks up, we should get a line spectrum from both ele- 
ments; but the metallic lines wou e€ more intense* than 
those of the non-metal, owing to the greater sensitiveness of the 
metallic molecule. e should thus have realized the condi- 
tions laid down in a former paragraph (7), where A would then 
represent the metallic, and B the non-metallic vapor. 
t now remains to show the applicability of the foregoing 
principles to the case under consideration. 
e oxygen and hydrogen of the sun’s atmosphere will, for 
the sake of simplicity, be exclusively considered. These gases 
been weakened by general absorption or by removal to a dis- 
tance. It has been shown in paragraph 8 that the total radia- 
tion of the photosphere has probably undergone a great amount 
of weakening from both these causes. Thus the spectrum of a 
ray which reaches the zone of combustion would exhibit (sup- 
posing the zone of combustion and all exterior to it to be 
stripped off) the lines of oxygen and hydrogen dark, but those 
of the former much fainter than those of the latter. The action 
of the incandescent gases of the zone of combustion upon such 
a spectrum would be to reverse the oxygen lines and to weaken 
those of hydrogen. 
The temperature of the region outside the zone of combustion 
must fall off, so that any oxygen which might there exist+ would 
be in the state of molecular aggregation corresponding to the 
compound spectrum, and would thus be without action on the 
bright-line spectrum of this gas, but would give rise to the dark 
lines of its compound spectrum. The hydrogen of the region now 
under consideration by further absorption intensifies the lines of 
this gas. Thus the solar spectrum as now known is shown to 
be in complete accordance with the hypothesis here advanced. 
* "In a tube containing both nitrogen and aqueous vapor, the lines of hydrogen 
II order) made their a ce at the same time as he spectrum of 
i also nd 
containing hydrogen and nitrogen, the lines of the latter gas under certain condi- 
re could to 
tions of pressu made to disappear entirely, while the hydrogen lines 
conditions remained visible (Proc. Roy. Soc., xvii, 454) 
1S aay be sup’ that the oxygen atmosphere tes with the zone of 
' in which case Dr. Schuster’s new oxygen m 
by the absorptive action of the gas in the upper regions of the chrom (see 
also note to paragraph 7). 
