The native Virginian. [volume] (Orange Court House, Va.) 1867-187?, 1869-08-20
:. FRIDAY MORNING AUGUST 20. 1869.

not change their position, but they In
| stantly turn dark. The explanation is
that the candle flame absorbed the same
rays :hat 1t gave out-that is, it sop
ped the bright sodium rays of che elec
trie light, and, letting all the others
pass. the contrast becomes so great in
the spectrum that the lines If absorp-
ton appear as dark lines. Now in the
sun it is supposed that there are two
sources OF light, al external photos
phere, and an inner nucleus OF intenser
brightness, So that the intenser light
from the inner source undergoes alb
sorption as it passes through the outer
sphere, and hence the solar liues ap-
pear dark. A beautiful verihcation of
this principle is I'll, nished by discov-
cry OF Iockyer and Jansen that from
the. very outer edge Of the sun. and con-
sequently where we do not get the rays
from the nucleus. the solar spectrum
gives bright Lines; this outer Sphere is
therefore termed lhe chromosphere.
The constitution of the sun is now
held to be proved by spectrum analysis
that is. we know TO Il moral certainty
that certain elements existing on the
earth exist also here. The spectrum of
iron vapor. for example, gives us sixty
for seventy bright lines! If ltow we
place this beside the solar spectrum.
che bright lines are found exactly to
correspond to u system nf dark lines in
number, breadth, position. and inter-
spaces-a coincidence. that. Sixteen
OF tile elements we know upon earth
are thus found to exist in the sun. The
spectra of the stars have been studied
with glea: a$siduity and success by
aiher Sechi of Rome, Mr.. higgins OF
London, al d Mr.. Rutherford 0t this
city. About eighty lines in the spec
trum of the star Aldebaran have been
mapped, and it has been shown to con-
tain sodium. magnesium. hydrogen,
bisniuth, tellnriuni, aatimony, an d ner-
curry. while Sirius gives indications of
the presence of sodium, magnesium, |
IRON. aud hydrogen.
But the uses ot spectrum analysis are |
not confined to original chemical re-
search: it has practical applications
which should not pass unnoticeJ. In |
lie BesSener process of converting cast
ron into steel it is of great value. Cast
ron differs from steel in containing
more carbon. and is made into steel by
burning out the carbon by means OF Il
blast OF atmospheric air sent through
lie wEite-h0t. molten mass. Five tons
't cast-iron, by his process; are con-
'erted in twenty minutes into cast
teel. The success oil the operation de-
,ends ulon the blast being stopped ut
he right moment, fol- If discontinued
90 soon the mass becomes too viscid to
,e poured out, or il continued too long
t crnmbles under the hammer. By aid
u the spectroscope the appearance and
disappearance nj the lines in the flame
-fiord an exact index to the progress OF
he combustion. This instrument il
.lso proving a valuable ally to Justice
II ltspfitience in criminal cases. 1t de-
ects with inerring certainty even the
part of grain OF the
ed coloriug matter of a blood sta in.
LII Is difficult to convey clear ideas of
he subject treated by Prof. Roscoe
Without the aid al diagrams: he has ac-
oi dinghy illustrated his work piofusc-
Y and beautifully. 1t is in the form OF
,ctufes. clear and popular in state
ient. and in fhe absence of Il course of
Xpei mental demon stritions it is the
ext best thing. The publishers have
ertormed their part with skill and pro-
uced work which it is not too mitch
, say is worthy Of its theme. 49,.