The Elk Mountain pilot., 1882-07-20
PRACTICAL INSTRUCTIONS FOR COLaR[NG
AND PlCKllNG GOLD lLlaTS
n Z. sculaaa ~ VIENNA.

AND PEkllNt tVLD M3M
| n T. scuLaasa. - VIENNA.
Gold alloys. particularly those thai
contain copper, acquire. through re.
peated heatings that take place during
their manufacture, an unseemly browa
or brownish black color, caused b
the oxide Of copper. To remove this
they ase beiled or picked in very 'di.
lutte sulphuric or hydrochloric acids.
according to the color they are to
have.
live have an alloy containing only
gold and copper, either sulphuric OF
hydrochloric acid is employed, tor
gold is not attacked by either Of them.
while the oxide of copper dissolves 50
easily that after the picking the arti.
cles have the color Of pure gold, for
the surface is covered with thin film
of gold.
If the alloy consists solely Of gold
and silver, the liquid employed is
nitric acid, and the articles are left in
it only very short time !; the acid
dissolves a very small quantity of sill.
yer, and hence the articles acquire the
color OF gold.
If the alloy contains both copper
and silver, besides the gold, the method
Of pickling can be varied to suit the
color that it is desired to give to it.
If, for instance. it is put in sulphuric
acid, the copper alone is dissolved,
and the color obtained is that of an
alloy of gold and silver, for the
surface consists of these two.
If nitric acid were used, both copper
and silver would be dissolved, and in
this case the color obtained would be
that of pure gold.
Tie articles are gently heated and
allowed to cool again before boiling.
The object OF the heating is to des-
troy any grease or dust that adheres
to it. If they are soldered with soft
solder. they cannot, of course, be
heated, and must be cleansed from
grease and dust by first putting them
in very strong lye, then washing
with water and putting them IN the
acid.
The acids are used dilute, usually in
the proportion Of one part of concen-
trated acid to forty parts Of water.
The articles are laid side by side in a
porcelain or earthenware dish and the
dilute acid poured over them. From
time to time one is taken out to see If
they are yellow enough yet. When
the proper color has been reached
they are washed in clean water and
dried.
While this picking is merely to
bring out the color Of the gold, the
coloring Of gold has tor its object the
'mparting to inferior goods the ap-
pearance Of very good gold. Differ
ent mixtures can be employed for COL
oring gold, two Of which are given
below as giving very good results.
Mix together two parts Of saltpeter,
one part of table salt, and six parts Of
alum. with SIX and a half parts Of va
ter, and warm the mixture in a por.
cela'n vessel. As soon as it begins to
rise add one partof hydrochloric acid,
and bring the contents Of the vessel
to a boil, stirringi it the meantime with
4 glass rod.
The articles to be colored, suspend
ed on hooks made of strong platinum
wire, orot glass, are 6vs dipped in
salphuric acid and then put in the
slowly cooking solution last described
and moved to and fro in it. In about
three minutes they are taken out and
dipped into large vessel Of water 80
IS to see what color they are. II the
desired shade Is not yet attained they
are Dipped in again as oftea as neses-
sary until they do have It. In the
subsequent dippings they are are only
left in the liquid ior one minnie.
Articles colored in this way have a
hight yellow color, bat matte appear
ance. They are repeatedly vasAed
in water 10 remove tie last tsace oi
the liquid. aEd then dried u soft asw-
n q