The daily dispatch. [volume] (Richmond [Va.]) 1850-1884, 1873-03-01

aWhen the 1aurels bloom" sailor!
Say'st thou when the laures bloom
They are blooming now and ever,
Fadsless, on thy honored tomb!
Lexington, February, 1879. d.
Spectrum AnnIys,s-W What Ii HAS Done
for Physics, Chemistry, and Astro'i-
OiMy.
By spectrum is not understood in physics a
spectre or ghostly apparitioD, as the verbal
Interpretation Of the word might well lead
one to suppose. but that beautiful image
brilliant with all the colors of the rainbow,
which Is obtained when the light OF the sun
or any other brilliant object is allowed to
pass through triangular piece OF siaSs-a
prism.
The unassisted eye can perceive no differ
ence IN the light from the heavenly bodies
and that from various artificial sources, be-
yond variation in color and brilliancy; but
it is quite otherwise when the light is viewed
through a prism. There are then formed
very beautiful colored images or spectra, the
constitution and appearance of which de-
pend upon the nature Of the substance emit
ting the light. The different appearances
presented by these colorcd images are SO en-
tirely characteristic, that TO every substance,
when luminous in q gaseous form, there cor
responds peculiar spectrum, which belongs
only to that peculiar substance.
1t follows, therefore, that when the spec
tra of different substances have been deter
mined once for all. by previous researches,
and have been recorded in maps or impress
> ed upon the memory, it is easy in any fu-
ture investigation TO recognize at once from
the form of the spectrum, which body OF
unknown constitution presents, tho lndlvi-
dual substance of which it is composed.
This statement presents in general terms
the nature Of spectrum analysis. ltanalyZeS
bodies into their constituent parts, not az the
chemist, with alcmbics and retoris, with re-
agents and precipitates, but by means Of the
spectrs which these substances give when
IN state of intense luminosity.
Spectrum analysis in no way supplants
the methods of chemical analysis hitherto i'll
use; for its function IS neither to decompose
Tor to combine bodies, but rather TO recon-
nOitre an unknown territory, and 10 stand
sentinel and to sjgnalze to the phySlcist, the
chemist, and the astronomer, the presence of
any substance brought beneath its scrutiny.
With what acuteness, with what delicacy
does spectrum analysis accomplish this
task! When the balance, the microscope,
and every other means of research ut the
command Of the physicist and chemist utterly
fail, one look in the spectroscope Is sufficient
in most cases to reveal the presence of sub
stance. If pound Of common salt be divi-
ded into 100000 equal parts, the weight OF
one Of these portions Is called Il milligramme
The chemist is able, by the use Of the most
delicate scales and the application OF SPECIAL
skill, to determine the weight of such par.
ticle; but, in doing 70, he comes close upon
the limits of his power Of detecting by chem
lcal means the presence of sodium, the CHIEF
element In common salt. But II that small
mlligramme be subdiyided into three million
parts, we arrive at SO minute particle that
all power of discerning it fails, and yet even
this excessively small quantity is sufficient tc
be recognized with certainty in spectre
scope. We have but to strike together tho
pages of an old dusty book in order to per
ceive Immediately in the spectroscope placed
. Mt some distance, that the flash OF line 0
yellow light which we shall presently leart
is nm unfailing siga Of the presence OF sodium
It was to DO expected that so sensitive ;
means of investigation, from which no known
substance eau escape, would very soon LEAF
70 the tracking out and discovery OF new elc
ments which, till then, had remained uu
known, either because they arc scattered
very sparipgly in nature, or stand out with 81
substances, that the imperfect chemical me
thods hitherto in use have not been able Il
distinguish them.
This expectation was brilliantly realized
even by the first steps taken in this direction
The two Heidelberg professors Bunsen ant
kirchhotf, 10 whom we are indebted tor tht
discovery of spectral analysis and its appli'
cation to practical science, very soon dis.
covered with their new instrument two new
metals, csssium and rubidium, 10 which two
others, thallium and indium, have been since
added.
But all the brilliant and astounding results
which spectrum analysis has furnished In the
provinces of physics and chemistry have been
far surpassed by its performances in that OF
astronomy.
It's possible by means of prism to de.
compose into its component parts the light
of the sun, the planets, the fixed stars,
comets, nebula, and thus obtain their spcctr,i
in the same way as that Of earthly luminous
substances. by careful comparison of the
spectra of the stars with the weli-known
Spectra Of terrestrial substances 1t can be
determined, FROM their complete agreement
or disagreement, with q certainty almost
amounting to mathematical precision, whe.
ther these substances do or do not exist in
those remote heavenly bodies. The fore.
going statements present in general terms
the essence and scope of spectrum analysis
Its starting point is the spectrum of each
individual substance, and in order to obtain
this it is requisite that the substance should
not only be luminous, but should emit sui
ficient quantity of light. Dark bodies are
not available for spectrum analysis. If the,
are to be submitted to its scrutiny they mus
first be brought into state of vivid lumi
nosity.--From Spectrum Analysts Explained
by Schellen. :