Los Angeles herald., 1907-05-26

- tlliZing the latter metal and the
same process was employed IN Sill
vering. In 1903, Bruguateli succeeded in
gliding the baser metals by means of galvanlc
current but the first to make the process
success was the chemist De La Rive, and IL
has since been greatly improved by later in
ventors.
The process depends upon the peculiar power
which the voltaic current possesses, OF sep
arating certain compound bodies into their
constituent parts.
For instance, if current from a voltaic
battery is passed by means of platinum cleo
trodes through water to which suphuric acid
has been added, this chemical separation,
which is called electroysis, will take place,
the water being resolved into its constituent
gases, oxygen and hydrogen.
Now, if some sulphate OF copper is thrown
into the liquid, electroloysis will still go on,
with double result-the water will be sep
arated into its elements, anad the hydrogen,
by its stronger affinity, will form new COM
pound with the sulphur in the suphate, set
ting the copper free; and the liberated cop.
per-, being electro-positve In character, VIII
be deposited on the platinum electrode. which
is negative.
On this general principle the process Of
electro-plating, or electrotyping, depends, and
it's art consists in applying the metals thus
released from their solutions to artistic and
useful purposes. The solutions generally en-
ployed as electrolytes, from which to separate
BOiu anu SILVER Tt5peCJlNey, are buoSG VI
| the argento-cyanide and the auro-cyanide Of
| potassium.
These componds are what are known to
chemists as double salts; that is, while eva:
nide of potassium is simply compound Of
potassium and cyanogen, argento-cyanide of
potassium is cyanide of silver combined with
cyanide of potassium. When a solution Of
this double salt is subjected to the action Of
electricity silver appears at one e. eeetrGde
of potassium, from which the other salt
had been thus separated, reappears in the
solution
1T is the negative electrode which takes the
silver, and if, therefore. the positive electrode
is made Of silver the liberated cyanogen COM
bines with it., forming cyanide Of silver,
which, by uniting with the liberated cyanide
of potassium, keeps the strength of the solu.
tion to the proper degree: The apparatus used
in which is smaller vessel of biscuit ware
or other porus material.
In the smaller vessel is placed the sulphuric
acid. with a plate. of amalgamated zinc, The
in it, is suspended the object to be .silvered
or glded, which is connected by wire with
the zinc in the cell to convey the galvanic
current; The strength of this current must
electricity developed will be more than suffi.
eient to release the metal, and hydogen will
be evolved, which will interfere with the
plating process To carry on electro-plating
! on large scale, ODlOng VatS are used, winch
may hold two hundred gallons of solution.
Silver plates connected with a powerful
voltaic battery are placed at intervals in the
vats; they form the positive electrodes, and
correspond in extent of surface with the ar
ticles to be coated, and face them on both
sides.
These articles-knives, forks, spoons, cruet-
frames, teapots urns, etc.-act as the negative
electrodes, and are suspended by copper wires
from brass rods laid lengthwise over the vats
and connected with the battery.
The articles are prepared for plating by
beng first boiled in strong lye, to free them
from all grease; they are then quickly dipped
in muriatic acid to remove any oxide that
may have formed on the surface, and after this
are well washed in water to remove every
trace of the acid.
They are then dipped into solution of
mercury, and then washed in water again.
The effect of the latter operation is to make
the film of silver adhere more readily. The
articles are then weighed and suspended in
the solution, and are left there until suff-
cient amount of silver has been deposited up
on them.
This amount is tested by weight If the
additional weight is not gained within the ex-
pected time, the article is put in the solution
again.
When finally taken out, the articles are
brushed with brushes of fine wire and cleans
ed with fine sand they are then polished on
revolving brushes with rottenstone, then with
chamois leather and rouge and lastly with
the naked hand.
| The process of electro-gilding is essentially
the same as that given above for silvering,