THE 
LONDON, EDINBURQH, and DUBLIN 
PHILOSOPHICAL MAGAZINE 
AND 
JOURNAL OF SCIENCE. 
[FIFTH SERIES.] 
DECEMBER 1883. 
LVIII. On Sun-spots and Terrestrial Elements in the Sun. 
By Gr. D. Liveing, M.A., F.R.S., Professor of Chemistry, 
and James Dewar, M.A., F.R.S., Jacksonian Professor, in 
the University of Cambridge*. 
[Plate VI.] 
THE publication of spectroscopic observations upon sun- 
spots made at Greenwich places within our reach a 
gradually increasing body of facts bearing on solar chemistry; 
and though we have not made a special study of sun-spots, yet 
the points of contact between the appearances presented in 
sun-spots and those observed by us in the spectra of terrestrial 
substances are so many, that we think some discussion of them 
will be of interest. 
The spectroscopic appearances of sun-spots in general point, 
as all, we believe, are agreed, to the conclusion that in a spot 
we are looking through an unusual depth of the solar atmo- 
sphere charged with metallic and other vapours: that for some 
reason there is at a spot a depression in the general contour 
of the photospheric clouds, so that the light which reaches us 
from the spot has come to us from a greater depth in the sun 
and been filtered through a greater thickness of absorbent 
gaseous matter. The depression in the photospheric cloud 
may be the result of some of the violent atmospheric motions 
which are frequent in the sun, moving the clouds about and 
causing a downrush at the spot ; or it may be the result of an 
ascending current of vapour at a temperature higher than the 
* Communicated by the Authors. 
Phil. Mag. S. 5. Vol. 16. No. 102. Dec. 1883. 2 F 
