The Sedalia weekly bazoo. [volume] (Sedalia, Mo.) 187?-1904, 1891-06-16
FACTS ABOUT GOLD.
A Single Ounce May Ee Spread Over One
Hundred square Feet.

A Single Ounce May Be Spread Over One
Hundred square Feet.
Pure gold Is so soft that it would soon
be worn away by use and ii is always
alleged with q varying proportion OF
copper or silver, usually about one
tenth. Pure gold is said to be "a carata
Thus 1s-carat gold contains Is parts OF
the pure metal 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
{l93) Is the best test of its purity,
though this has been ingeniously imi-
tated by covering the heavy but cheaper
metal, platinum, with layer Of gold
Iron pyr;tes and other yellowish miner
ais are constantly be ng mistaken for
gold, by inexperienced persons, much
to their disappointment but very sim
pie test will show whether doubtful
specimen is real the true metal Gold
Is very socts,e-that is, it can be cut and
shaved with 4 knife, like piece of
wood or horn; while pyrites and other
the knife-blade like lump Of sugar.
If any reader OF this article ever finds
yellowish mineral which can be cut
without crumbling. it is worth more
thorough test; otherwise be may as well
save himself unnecessary trouble and
disappointment Very few chemicals
have any effect Oh gold. Selenic acid
will dissolve it, but few chemists have
ever seen this very rare substance. A
mixture Of nitric and byjroch!oric acids
(agud regia) VII also dissolve it. form
ing a chloride Of gold; and so will solu-
ton of chlorine gas in water. In both
these liquids a peculiarly active form
of chlorine, known as nGscent 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 Cass Us, a compound
of tin and gold of uncertain compost
ton. but yelling q magnificent ruby
color when melted into glass A hun
dredth of grain of gold will deeply
color cubic inch of GAS. The most
extensive use of the chloride is, how
ever, in photography. where it is used
to tone" or color prints on silvered pa
per. This darkening of the prints is
due to the decomposition Of the salt
and the deposition in the picture OF
hnely-divided metallic gold, which not
only gives it the desired color, but rem
ders the image very permanent By
beating out between p eces OF mem
brane. gold may be formed into leaves
of such thinness that $4,000 Of them
will only make pile one inch in
height A single ounce of gold may
thus be spread over one hundred
square feet In the manufacture of
gold thread for embroidery, a cylinder
Of silver is covered with gold and after
wards drawn out into wire. In this way
SIX ounces of gold have been made to
yield over two hundred miles of gilt
wire. Even at this extreme tenuity the
roat.ng is perfect and does not rust or
tarnish.-Popular Science News