The Sedalia weekly bazoo. [volume] (Sedalia, Mo.) 187?-1904, 1891-08-11
FACTS ABOUT GOLD.
A Single Ounce May Be Spread Over Oss
Hundred square Feet.

Single Ounce May Be Spread Over Oas
Hundred Square Feet.
Pure gold is so soft that 1t would soon
be worn away by use and 1t is always
alleged with a varying proportion OF
copper or silver. usually about one
tenth. Pure gold is said TO be "a carats
Thus. lS-carat gold contains Is parts OF
the pure mctai in "a. or, is three-quar.
tiers pure. Many cheap alloys of base
metals can be made which very strongly
resemble gold in color and luster; but
IN the absence OF a complete chemical
test the high specific gravity of gold
C93) Is the best test of its purity.
though this has been ingeniously imi-
lated by covering the heavy but cheaper
metal, platinum, with layer of gold.
Iron pyrites and other yellowish miner
ais are constantly being mistaken for
gold. by inexperienced persons, much
to their disappointment. but a very sim
pie test will show whether a doubtful
specimen is really the true metal. Gold
Is very secf;I-that is, il can be cut and
shaved with a knife, like 4 piece of
wood or horn; while pyrites and other
worthless m nerals will crumble under
the knife-blade like \ lump of sugar.
IL any reader of this article ever finds a
yellowish mineral which can be cut
without crumbling. it is worth a more
thorough test; otherwise he may as we'll
save himself unnecessary trouble and
disappointment Very few chemicals
have any effect on gold. Selenic acid
hnt IA, nka
ever seen this very rare substance. A
mixture Of nitric and hydrochloric acids
(aqua regia) will also dissolve 1t, form
Ing chloride Of gold; and SO will solu-
ton OF chlorine gas In water. In both
these liquids peculiarly active form
OF chlorine, known as nascenf chlorine, Is
present which probably unites directly
with the metal Gold, like all the noble
metals Is unchanged by heating in the
air Its oxides can be obtained by
chemical reactions but they are very
unstable, and easily reduced back to |
the metal The chloride above referred
to Is the only salt Of any practical i'm |
portance. and Is used to produce the
beautiful Purple Of Cassius a compound
Of tin and gold of uncertain compost.
ton. but yielding q magnificent ruby
color when melted into glass A hun.
1redth Of grain Of gold will deeply
color cubic inch Of glass The most |
use of the chloride is, how
ever. in photography, where it is used
to tone" or color prints on silvered pa
per. This darxening of the prints is
iue to the decomposition OF the salt
md the deposition in the picture Of
inely-divided metallic gold. which not
'nly gives it the desired color. but rem
lers the image very permanent By
'eating out between pieces of MEM
'rane, gold may be formed into leaves
# such thinness that 2s2 900 Of them
will only make pile one inch in
eight A single ounce OF gold may |.
nus be spread over one hundred
quare feet In the manufacture of
old thread for embroidery. a cylinder
silver is covered with gold and after
ards drawn out into wire. In this way
* ounces of gold have been made to
ield over two hundred miles of gilt
ire. Even at this extreme tenuity the
oat.ng is perfect and does not rust or
Science News