The Norfolk Virginian. [volume] (Norfolk, Va.) 186?-189?, 1896-02-14
ErFEcT OF HEAT ON GEMs.

EFFECT OF HEAT ON GEMS.
AS TO the action of very high degrees
OF heat on precious stones. we have not
many data. The Emperor Francis l.. OF
Austria, and his brother. Charles. the
Archduke of Brussels, in l1bl, EXPERT
mented with various precious stones
exposing them to fires of various, inion
sites. They placed diamonds and ru-
bes TO the value of 5000 guldens In n
strong carthen vessel which they eS-
posed to intense fire. After twenty
four hours the rubies were entirely nm
injured, but the diamonds had com
pletely disappeared. The rubics were
then exposed for three entire days to
the strongest heat but without the
slightest change either in appearance
weight, density or color. In second
experiment twenty-four varieties of
precious sd9nes were all exposed to an
intense fire. They were carefully
weighed both before and after the
heating. and We're taken out every two
hours until the diamonds had entirely
disappeared. The emerald after two
hours was molten mass; some were
calcincd. and others were entirely nm
inin~rd
Very remarkable is the fact that
great heating alters the molecular
structure If all precious stones. The di
amend alone changes chemically.
air. The ruby, sapphire. emerald, aqua
marine. quartz and some other gems.
while the chemical composition is not
altered by extreme heating. are
changed physically. becoming no hard
Ell than glass, and their specific gravity
is lowered: hence the impossibility Of
fusing fragments or small gems into Il
lar.e one, as Is claimed for ARTIFICIAL
,ubieS.
After speaking OF color CHANGES pro-
duced In precious stones by heat and
light, we are led to n related, though
quite different phenomenon. which
should also be m-ted among the physi-
cal properties of gems, This is phos-
phorescence. the emission Of light I'm
the dark, which appears in some gems
after being heated, rubbed or exposed
TO strong light This singular phenome-
non was doubtless observed very early;
It gave rise to a host of marvellous
tales about luminous gems, with which
Eastern and other literature tradition
abound. The eminent chemist, Prof.
Draper. says: IA belief in the exist
ence Of the carbuncle, n stone supposed
TO nave the PR perty of shining in the
dark. appears to have been current
rom the very infancy of chemistry. II
gave rise to many legends among the
alchemists, and early travellers relate
marvellous stories respecting self-sMin-
s..
said that the King Of Pegu wore Il car
buncle so brilliant that IL any Of his
subjects locked upon him In the dark.
MS countenancc seemed radiant and
mat In certain part OF North America
there was mountain that illuminated
the country for many miles. and served
10 guide the Indians at night" This
luminous mountain referred to by DR.
Draper seems to have been somewhere
in Western Pennsylvania. The eminent
English philosopher, Robert BOYLE.
speaks of the story. and tells how an
early explorer undertook to visit it, and
seemed to see 1t from distance: hut
as he drew nearer the light diminished.
and he could not reach or identify the
spot
OBSERVATION-DISCLOSURES IN GEMS.
European expe-imenters have made
much investiga ton lately as to this
phosphoresccnce. and the manner of OK
citing it, The property Is not so rare
as often imagined; many bodies display
II. though In different ways. Some
times. as in prophorous itself. it Is re-
ally show combustion. and IS chemi-
cal rather than physical phenomenon;
but in many bodies 1t is strictly physi-
cal. neither accompanied nor caused by
any chemical change. Sometimes it
results from heating; sometimes from
friction, IS in diamonds: sometimes
from exposure to light. With diamonds
phosphorescence by friction is common
perhaps unirersal by light 1t Is caused
in some diamonds, but not in ALL
Although not stated in any work on
mineralogy since the time Of BOYLE
over two centuries ago, 1t seems that
all diamonds emit light in the dark, on
being rubbed or struck even quite gent
~. If rubbed, or brushed against
linen or wooden fabric, or the leather
cover of book, or drawn across
piece Of wood of any kind. flash of
light appears. I have tested a large
number of diamonds, of all sizes and
various colors. and from different l?cal-
tiles, with results uniform as to The
fact, though differing in degree. Those
diamonds that phosphoresce by the &C
ton OF light. are most markedly af
fectcd by friction. But the property
varies IN degree among diamonds. DR.
Draper found that those glowing male
Blue had the longest residual o,rTy ,n5