Evening star., 1876-12-09

From the Ne,c York Schooy Jots1Yldll
When the diamond is rubbed IL becomes
positively electrical, evenbefOTe being cut, in
which il differs from all other gems. When,
after exposure to direct sunlight. il is sud-
denly placed in darkness, il shows phosphor-
escence, and the evolution of light continues
for some time. II is not acted upon by any
acid or alkali. But IL may be consumed and
completely oxidized TO carbonic acid at a
nigh heat I'm the atmosphere. 1t is so difficult
10 burn that the ordinary blow-pipe flame
has no effect upon il. 1t may be heated to
whiteness IN closed crucible without change
but II begins to burn in muffie at the melt
ing point of silver. At n high heat with nit
rate of potash il is rapidly decOmpOsed.
Miners are generally not familiar with the
appearance of diamonds in the rough state,
ard would most likely mistake them, if
found. for chalcedony or some similar mine
raj. Ii i'm crystal form IL would be tOlthem
n crystal Only-interesting for the moment,
TO be soon thrown aside as useless: / have
heard OF case where a beautiful crystal;
supposed to be a diamond, being found in
some placer mine in California, was put to
the following test: II was placed on an anvil
and struck heavy blow with a sledge ham,
mer il being assumed that the diamond, be-
ing the hardest Of known substances, could
not be broken. This idea is more ancient
than is generally supposed. The statement
has been made by Pliny, but il is doubtful if
he ever made the experiment himself. In
speaking of a diamond, he says that il can
not be crushed, but would split hammers and
anvils in the attempt II is certain that this
is mistake The diamond can be split on
the edge of a knife and even a light blow
with hammer might destroy the most costly
gem.
The diamond is supposed to be of vegetable
origin. and il is believed, by those who have
studied it carefully, to be produced by slow
decomposition OF vegetable or bituminous
matters. zone large diamond having
black spot in il was cut i'm two and the defect
was found TO be vegetable mud enclosed in
the cryStal)
1t requires practice to judge of the diamond
in its rough state. A rough diamond of the
first water would be hardly recognized by the
uneducated eye as valuable gem. In des-
cribiDg the diamond many of its characteris-
tice are visible only i'm its cut state. Half
the stone is sometimes cut away before q
perfect gem can be produced. The diamond
washers OF Brazil rub the stones together and
produce peculiar grating sound, from which
they assume to judge of their value.
There is peculiar appearance about a
rough diamond which can hardly be deScrib-
ed. question if any written description
would convey 10 the reader n correct idea of
what they are exactly like. 1t is easy to say
that they possess a peculiar luStre' like spcr
maceti, but who would feel certain Of the
identity of a diamond from such discrip-
tiOn? once seen this peculiar lustre becomes
impressed on the mind. To educate the eye,
models of rough diamonds are made at
Amsterdam for the use of prospectOrs, and
they are found extremely useful.
Newton first suggested the probability, OF
10 this opinion by observing its power of re-
iracting light so strongly. 1t was in 1916 that
he advanced this theory: In 1854 the MEM
bers of the Academy of Florence succeeded
by means of powerful lenses in consuming
diamonds. LavOisier and others proved that
the diamond was not evapOrated, az supposed
by the Academicians, but was actually
burned. Lavoisier found by his experiment
that if air was excluded no decomposition
took place. He burned diamonds in close
vessels with powerful burning-glasses, and
found that carbOnic acid was produced. and
discovered and announced the striking siini-
larity between their nature and that OF char
coal.