EDITORIAL OBSERVATIONS. 
291 
For instance, it has been asserted that the bright red band 
of the potassium spectrum coincided exactly with the con¬ 
spicuous dark band known as A in the solar spectrum; 
but M. Morren finds them to deviate by fully a third of a 
degree. It is also found that the spectra of certain metals 
become progressively enriched with coloured bands as the 
temperature of their vapour is raised. The spectrum of 
iron, as given by a powerful battery of 65 Biinsen^s elements, 
contained so many lines that they were counted with diffi¬ 
culty ; whereas the iron spectrum, as shown in the flame of 
a feebler battery, contains comparatively few lines. The 
yellow band of the sodium spectrum is found to be developed 
in the -spectra of mercury, and of several other metals, at a 
very high temperature. The coincidence of the solar band 
D with the yellow band of the sodium spectrum cannot 
therefore now be regarded as proof of the presence of 
sodium in the sun^s atmosphere. The temperature of the 
sun is vastly higher than any temperature yet obtained by 
artificial means on the earth ; and who can tell from the 
lines of metallic spectra as exhibited by artificial heat, what 
modifications they may undergo in the intense incandescence 
of the solar atmosphere ? Dr. Frankland, in a recent ex¬ 
periment upon the lithium spectrum, was astonished by the 
appearance of a splendid blue band, such as was supposed to 
be peculiar to strontium. This startling blue line was found 
to have been developed by the high temperature of the flame 
used. With an ordinary Biinsen^s burner, no such lines 
appeared, but only a familiar lithium spectrum. Dr. Frank- 
land seems to have been led to this solution of the mystery 
by the knowledge that lithium burns in the air with a 
crimson light; but that, when plunged into oxygen, where 
the combustion is far more intense, its flame is bluish white. 
These discoveries, although tending to impugn early specu¬ 
lations, will probably help us at last to some definite and 
reliable conclusions in the department of solar and stellar 
chemistry. 
