The Sun.
London, England, 1861-11-01 00:00:00

SPECTRAL ANALYSIS.

e some time ago gave an account of Mr. Crookes's dis-
covery of a new element, closely resembling sulphur, by
means of the spectrum obtained by the transmission of the
light emitted by the flame of certain substances through a
prism, just as is done with the sun-light, which, as is gene-
rally known, is thus decomposed, giving rise to the colours
of the rainbow. The Illoniteur now publishes a highly
interesting article, from the pen of M. Dumas, on spectral
analysis, of which we give the substance :—The solar spec-
trum transmitted through the prism is wanting in certain
shades of the seven colours, and their places are occupied
in the spectrum by black bands or streaks, If we sub-
ject the light of the moon or planets to the same
analysis, we shall find these bands in exactly the same
places ; but if we analyse the light of the fixed stars by the
same method, we shall find that the black streaks are not
arranged in the same way; nay, every fixed star varies in
regard to their arrangement. Artificial light derived from
different sources also furnishes spectra, in which, however,
we remark coloured and brilliant lines which are not to be
found in the solar spectrum. It is upon this fundamental
circumstance that the whole theory of spectral analysis
rests. All the salts of a given metal, when brought into
contact with a flame, produce in its spectrum brilliant
colours of the same tint and position; the salts of different
metals yield other colours, differing from the former in
shade and position ; and infinitely small particles of a metal
will suffice to produce its specific colours. Here, then, we
have a method of analysis of extreme delicacy; by
merely observing the spectrum yielded by a given sub-
stance, we can at once ascertain its nature or its ingre-
dients with astonishing accuracy. Let but a thousand-
millionth of a gramme of kitchen-salt, for instance, be in-
troduced into a flame, and it will at once cause it to reveal
through the prism the characteristic lines and tints pertain-
ing to sodium. It is thus M.M. Bunsen and Kirchhoff, pro-
fessors at the University of Heidelberg, who have just been
decorated by the Emperor of the French, as our readers
know, have been enabled to ascertain that certain elements,
supposed to be very rare, such as lithium for instance,
,are
fr
extremely common, while at the same time they have
equent dis-
-
covered in certain sediments and rocks of very
currence new elements the existence of which had not even
oc
been suspected. These are rubidium and caesium, which
belong to the family of metals. But one of the most singu-
lar consequences deduced from spectral analysisis this
that we are enabled to ascertain the chemical composition
of the solar atmosphere. For, since the solar spectrum
is
uy that
de
oaf
ncdololiterasd, wwheicmh payeccuolnia:il aper-
tdaeivno
into
ofs
iclevretra,i certain s
copperhda e
these metals are wanting there; while e converse, the
existence
in the solar spectrum of certain streaks peculiar
to iron, chromium, and nickel, shows that these metals are
component parts of the solar sphere ; and, what is still
snore singular, silicium and aluminium, so abundant
our globe, are not to be found in the