Warren sheaf., 1881-07-13

lead, and the presence Of the oxidized lead
for some unknown reason aids the oxida-
tion OF the copper mixed in the gold and
carries it down with it in a similarly mys-
terious way into the pores Of the cupel
! There is left q little button Of gold and sill
yer lying in the bottom of the cupel This
is hammered to knock off the scales Of OK
ide that cling to it, and then rolled into a
ribbon nearly half an inch wide. This rib
ban is coiled up and put into little plati-
mum cup, the size of a thimble, and set in
to boiling nitric acid. The bottom Of the
platinum cup is perforated SO that the boil
the silver. 1t will not attack either the
gold in the ribbon or the platinum of the
cup. The coil is boiled ten minutes, and
then lifted out and boiled ten minutes more
in fresh acid. By this time the silver is all
eaten out of the ribbon and the gold left
porous, which makes it so brittle that if it
is pinched the little coil will crackle into
pieces in the fingers. It is accordingly sub
iected to just enough heat to cause the par
ticles to adhere. This little coil is now pure
gold. 1t is unpublished ard of a dull creamy
color. Nota particle of the gold has been
lost, but all OF the alloys have been re-
moved. It is again carefully weighed.
Suppose that whereas it originally weighed
1000 according to the system of weighing
explained above, it now weighs only S73.
This shows that the metal brought in to be
assayed contains S73 parts in 200 Of gold,
or, in other words, 81 $40 per cent Of it
is ure.
All gold is melted before it is assayed,
and having been assayed it must be melted
again in order to be refined. An addi-
tional quantity of silver is added to it for
tho san TQac of
in the process of assaying.
1t is. then melted and granulated by flirting
the motion gold from a ladle upon the sur
face of the water. The idea is to make the
gold fail in a sheet on the surface so that
it will break up into little faky masses.
This granulated gold is then dried. and for
convenience of handling is pressed into
! cheese shaped masses. These are cut up
and the pieces are put into boiling oil of
vitriol. The acid eats out the silver and
copper, which turns it blue. This blue
liquid is drawn off with siphen. The
boiling is repeated several times, varying
in number according to the purity requir-
ed, after which the gold is melted and run
into brick. shaped masses to be carried to
the treasure room.
The blue liquid which contains the cop
per and silver is run into tank and weak
ened With the addition OF water. Ihe effect
of this simple process is to cause the acid
to let go of the silver while it yet clings to
the copper.
"If you have a cat, said refner, of a
large size and good courage she will clear
the house of rats and mice; but if you get
a smaller cat, or one that is not quite so
courageous, she will let the rats rur and
conine herself to the mice. The mice in
this case are represented by the copper,
which the acid eats up with greater ease
| than it does the silver"
The blue liquid is now allowed to stand
in a lead lined tank, in which are suspend
ed also many long strips of lead. On the
lead beautiful blue crystals are formed with
points as large as needles, ana whose
scratch is poisonous. These crystals are
blue vitriol, or sulphate of copper, and are
sold as much for the making of Paris green
and other chemical products.