New-York tribune., 1873-01-01

zine ABOVE drawing gives the image as ~ appeared
the screen, and is reversed Thus although the
metal which was brought to vapor, laid in hollow In
tie lower piece of carbon it appeared the screen as
adhering the upper and river of flame seemed
TO pour from it upon the bright point beowl
THE BANDS UNALTERABLE CHARACTERISTICS.
We will now remove the thallium and put bit OF
silver in Its place. First observe the arc of slver Is
not to be distinguished from that of thalum 1t is not
only green like the silver vapor. but The shade Of
green Are they then alike PsmatIc analysis enables
us to answer the question 1t perfectly impossible to
confound the spectrum of ncandescent silver vapor
with that OF hallum. Here are two green bands in
stead of one Adding 10 the silver in camera bit
Of thallium obtain the light Of both metals and you
that the of the thaium lies midway between
the two green's OF the silver Hence this similarity of
color But you observe another interesting fact The
halum band is far brighter than the silver bands in
deed the latter have wonderfully degenerated the
bic Of thallium has been put In They not at all
bright as they were at first, and for a worth
knowing II is the resistance offered to the passage OF
the electric current from carbon to carbon that calls
forth the Of the current produce heat II the
resistance materially essened the heat would be
materially lessened aud lf all resistance abolished
thero would be beat at all Now thallIum Is a much
more fusible and vaporzable metal than the silver;
and vapor facilitates the passage Of the carrn
such degree to render it almost Incompetent to
vaporize silver But the thallium Is gradually
sumed; its vapor becomes less and less the resis
tance rises until finally you the two silver bands
brilliant they were at first The three bands Of the
two metals Of the same sensible brightness.
We have in these bands perfectly unaterable charac-
erstc Of these two metals You get other bands
than these two green from the silver other
than the single green band from the thaum other
than the three green bands that you have just from
the mixture OF both metals Every known metal has its
bands, and In no known case the bands Of diff
ma he uaada
test as to the presence Absence of any particular
metal. If we pass from the metals TO their alloys we
find noconfusion. Copper gives us green bayds, sno
gives US blue and red bands; brass alloy of copper
and zinc, gives the bands OF both metals, perfectly
unaered in position character. But not
fined to the metals the salts Of these metals yield tho
bands Of the metals. Chemical union Is ruptured
by sufficiently high heat, the vapor Of the metal
10 set free and yields its characteristic bands
This part OF the lecture might be said 10 be continu
ously illustrated. The various images displayed
upon the screen with great Except that there
was some impurity in the carbon used.
which gave In many Of the experiments
nothing. undertaken that not accomplished
entirely 70 tho sasfscoa Of the lecturer. A for the
audience. they would willingly have interrupted 10 sp
plaud but experiment trod rapidly the heels Of
another that they found opportunity except brief
outbursts Of stamping and clappine to express their
satisfsction.]
u- DIsCovERY OF THREE NEW METALS.
The chorides Of the metals are particularly suitable
for experiments Of thischaracter Common SALT for ex-
ample, 10 compound OF chlorine and sodium In tho
electric lsmpit yields the spectrum OF the metal sodium
The chlorides Of hthium and Of srontum yield In ike
manner the bands OF these metals. When therefore.
Bunsen and Kircbho after having established BY
haustve examination the spectra OF all known sub
sanoess discovered spectrum whose bands did not cor
rcspondto any known bands they Immediately inferred
the existence Of o metal They were operating -
the time upon residue obtained By evsporsting one Of
the mineral waters Of Germany. In thas water they
knew the new metal Was concealed but vast quantities
Of had TO be evsporsted before rcsdue could be OBJ
tanned suicient TO enable ordinary chemistry 70 sppe
with the metal But they hunted IL down. and 10 now
stands among chemical substances - he netsl robi-
dum. They subsequently, discovered . eseosd metal,
which they called cesium. Thus. having ufvs placed
spectrum analysis q safe foundaton. hsy demon-
strated it's capacy agent Of dscoyery Soon after
ward Mr.. Croohes pursuing this same sthod added 70
the st OF metAls the thsuo which yielded that bright
monochromatic green baud. - ~.
APPLICATION oy srEcTEun AxALYsB
This relates 70 ohenisa discovery upon earth vhcre
Che matsrials ara in oar own hands. But Krcbhos
shsvss ass vsessn analyds nlsAt b seslisa b ths