i879-] 
Proceedings of Societies . 
377 
“ Note on the unknown Chromospheric Substance of Young,” 
by G. D. Liveing, M.A., Professor of Chemistry, and J. Dewar, 
Jacksonian Professor, University of Cambridge. In the preli- 
minary catalogue of the bright lines in the specftrum of the 
chromosphere published by Young in 1861, he calls special at- 
tention to the lines numbered i and 82 in the catalogue, remarking 
that “ they are very persistently present, though faint, and can 
be distinctly seen in the spectroscope to belong to the chromo- 
sphere, as such, not being due, like most of the other lines, to 
the exceptional elevation of matter to heights where it does not 
properly belong. It would seem very probable that both these 
lines are due to the same substance which causes the D 3 line.” 
Again, in a letter to “ Nature,” June, 1872, Young says, “I con- 
fess I am sorry that the speCtrum of iron shows a bright line 
coincident with 1474 (K) ; for, all things considered, I cannot 
think that iron vapour has anything to do with this line in the 
speCtrum of the corona, and the coincidence has only served to 
mislead. But there are in the speCtrum many cases of lines 
belonging to the speCtra of different metals coinciding, if not 
absolutely, yet so closely that no existing spectroscope can sepa- 
rate them ; and I am disposed to believe that the close coin- 
cidence is not accidental, but probably points to some physical 
relationship, some similarity of molecular constitution perhaps, 
between the metals concerned. . . . So, in the case of the 
green coronal matter, is it not likely that though not iron it may 
turn out to bear some important relation to that metal ? ” In 
1876 he proves that the coronal line 1474 is not actually coin- 
cident with the line of iron. In the catalogue of bright lines 
observed by Young at Sherman, in the Rocky Mountains, it 
appears that the above-mentioned lines 1 and 82, along with D 3 , 
were as persistently present as hydrogen, the only other line 
approaching them in frequency of occurrence being the green 
coronal line 1474 of Kirchhoff, which was present on ninety 
occasions out of a hundred. It occurred to the authors that these 
four lines may belong to the same substance. An analogy in 
the ratio of the wave-lengths of certain groups of lines occurring 
in different metals has been already pointed out by Stoney, 
Mascart, Salet, Boisbaudran, and Cornu ; and the near coinci- 
dence observed by the authors in the ratios of certain lines of 
hydrogen, lithium, and magnesium, substances belonging to the 
same type, combined with a similar ratio in the wave-lengths of 
the nearly equally persistent lines of the chromosphere, greatly 
strengthens the probability of the assumption that these lines 
belong to one substance. The fadt that the two less refrangible 
rays have no representative in the Frauenhofer lines is by no 
means opposed to their belonging to one substance, since 
aluminium behaves in a similar way in the atmosphere of the 
sun ; and in the total eclipse of 1875 the hydrogen line li was 
not visible in the chromosphere, but was on the limit between 
