Year: 1873

You observe here are the several parts TO which nave
made reference Everything is here, the httle lne on
be examined melted When this placed IN the Name
it colors the fame peculiar color tne et ,r p@c cf
metal termed the slit and that light Is rendered parallel
by the lens in this end. AT the same time candle is
placed near the little telescope here and the nght re-


fleets the image of scale nom the surface OF the Pfs
into the telescope SO the eye sees tne scae py
of the reflected light and the spectrum Dy trans
mitted light so we have the position measured exactly
IN bands of light in the spectrum of the metal.


"a continuous spectrum here shown on the screen
and afterward discontinuOus one.l


We have here simply the light which comes from an


gnited carbon point. You observe this light with the
exception OF slight race nee oI t SUor r o'
YOU will observe that the light nearest IN ne 10 tne
original is the red, that being the least Deh te
light fnrthest from that is biue aud between that we
have light Of all degrees OF refrangibity Ihls spec
trm is called continuous spectrum ana Is produced
from light OF solid piece OF carbon heated by the
passage of an electric spark. - =. l.. A.,


If We take gaseous substance and treat IL IN the
same way we Will that the spectrum Will not De
continuous as before, but be interrupted ana WIZ oe
YOn notice referring brilliant bands of light ON the
screen that the spectrum very strongly banded which
stance experimented upon. The interrupted spectrum
gives evidence that the kind OF matter heaed 10 tue
temperature al which 1t evolves hight, as gas zap
AUTOGRAPHS OF SIMPLE SUBSTANCES.


The trst application which this ndivdua lizng OF
substances conduces chemical analysis. Chemists tell



the earth out OF which all compound substances-the
very large number we know-are made up. Now as in
bank the officers must be acquainted accurately with
ns y Se e eVSFg % GnS the SaE doe
ness and must, AT n glance fe.esmaSt W, w.
must be- acqnainted with the signnanua Of every
of these chemical substances with which he does pus-
ness Sixty-three bodies, It's true, IN place OF many
hundreds perhaps OF Individuals but eaeh one OF the
chemical substances has an aqograph 9i s own a. ql'


nct and sharp as II possible Tor human Que 10 b
We have simply then, To ask the question: what ls the
characteristic Of the autograph which metal writes OF
writes or Of lines which given in the spectruuof
individual metals, in order 10 ascertain what the SUD


II is observed that each different clement gives its
peculiar spectrums when converted INTO ap0r ana
ncandescen gas. and nothing more is needed but TO be
acquainted with the spectrum III order ~ detect e ee
in order 10 get the spectrum OF metal two tnsgs are TO
be done first the metal must be converted into vapOr,
for solid gives merely white light and II must be after
ward raised 10 temperature AT which IL gives Its own
peculiar light. The autograph only written when the
metal Is in state of ncandescent vapOr. Now, IL IS not
easy boil silver copper OF IRON but TO get them
into vapor do II Is not for after they
which they give light but unless do 1t we
get the spectrum aud We may 40 IL by means OF the
substances into vapOr thus producing their spectrum
Place bit sodium in the gasburneF, and II gives an
intense yellow light II We; we e1Tmlne Inn II through the


Now, 1 say, whatever temperature you expose these
one yellow line from sodium and two from htbium and
we get the lines although we place these sub
We boil sodium IN the low temperature or the
gssSurRei ohsr nnq lines s present Ioc feeble TO b
seen, which invisible but if we intensity that light
by putting the substance IN the OxyhydrOge flame or
in the intense heat of the electric arc, lines make
their appearance. The simple element sodium, which
s1yes us one single line in tins little instrument
when placed in connection with the electric arc,
gives nine lines. 80 hthluu, the spectrum
spge orange line in the spectrum when subjected to
action OF the electric arc, gives In addition mag
ncent blue hne. This first noticed when the first
O,s made that simple
the first who did II the distinguished scientist,
whose words sn echo through this hall, Prof Tynda.
lApplauseJ


CHEMICAL ANALYSIS vARIoUsLY ILLUSTRATED.


Another point 20 be noticed. II we place salt in the
fame of this burner examine its rays, observe
the same spectrum If used sodium salt Is made
up of chlorine sodium. The temperature of the flame


will not raise II to the point at which It gives light but
this temperature separates the soda and chlOrum Take
compound Of calcium, ana al ths INSTRUMENT you
you obtain a different spectrum. How do
obtain twol IL is according 10 the temperature Prof
Roscoe investigated this and found that oxide OF cal.
cium which we lime gives spectrum by itself,
and this spectrum observe here, the spectrum of
salt OF calcium, the spectrum OF oxide OF calcium; but
the temperature OF this fame is sufficient decom-
pose peculiar spectra that compound substances
give The spectral lines OF calcium itself and the spec
Of oxide Of calcium OF lime are different when OBJ
tanned by the electric arc.


Any present who has examined the spectrum OF
stTontium metal analogous TO calcium, will not fail
recognize its bright lines The lower is the spectrum
strontium obtained by the bame OF the burner; the
upper the spectrum Of the same substance obtained
by the electric arc.


lin iustrationlof the mode in whchkhemca analyses
may made the Professor then threw succession of
exceedingly beautiful specra OF metals upon the screen,
lithiums which gives crimson and orange lines
addition faint green and the bright blue line first seen
by PrOf Tyndal at the Lecureroom of the Royal Insti
tute; then the bright green band, character
istic Of magnesium the orange, green, and purple
of mercury, and the bright green bar obtained from
vapor Of silver Placed at the Slip the light gave the
green bar but passed through the prism, 1t resolved
itself colors which could only be distinguished
thus Cooper gave another green light zinc cne bright
red and three bright lines the last exceedingly dis
tnct The figure shows the apparatus by which