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2015UNIVERSITY OF ILLINOIS

Volume

Mrl0-20M'Of

lliiVEKtSfTY OF IlLIMISELECTRO-PLATING VAT, AND SMEE BATTERY.ELECTRO-PLATING

A PRACTICAL HANDBOOK



INCLUDING

THE PRACTICE OF ELECTRO-TYPING

BY J. W. URQUHART, C.E.



nT> r:tif!

^ HP

LONDON

CROSBY LOCKWOOD AND CO.

7, STATIONERS' HALL COURT, LUDGATE HILL
1882

[All rights reserved.]?3 7-

U. x £

LONDON:

PRINTED BY J. S. VIRTUB AND CO., LIMITED,
CITY ROAD.PREFACE.

When I commenced to write the following little
treatise my aim was the production of a hand-book
possessing some novel features. They are, briefly,
the greatest possible simplicity of language, and
the providing of working directions in all respects
applicable to the practice of the plating-shop and
the wants of amateurs. I have done my best to
combine these objects throughout the work. To
produce a scientific or theoretical treatise on the
art of electro-metallurgy was, of course, quite wide
of my aim. My desire rather was to put in small
compass, and plain wording, an exposition for
which I looked in vain when I commenced the
practice of electro-metallurgy without much know-
ledge of science.

I believe, strange as it may seem, that, without
much " rule-of-thumb," any ordinarily intelligent
man may become an expert in electro deposition
with a very little science indeed. This work has
been prepared for the benefit of that numerous
portion of the community who have not the advan-

4^7*7 .vi

PREFACE.

tages of a library of books, and who could with
difficulty understand them if they had. It is my
hope that the ordinary plater or amateur will find
nothing to puzzle him in its pages.

The work has been written, in a secondary sense,
to give publicity to the newest information concern-
ing the ever-progressive arts of electro-plating and
typing, and also to include particulars of Dynamo-
electric machine working. It is arranged in chapters,
a chapter being devoted to each important section
of the work. Much care has been taken to render
the book as useful as possible, by including all the
necessary information concerning materials, the
preparation of them, and their prices in commerce.
The subject of electrical generators or batteries
has received much careful attention, and will, I
trust, be found almost complete. I have also been
careful to omit questionable or doubtful methods of
working.

J. W. URQUHART.

London, 1879.CONT

CHAPTER I.

Introductory Remarks
Explanations of Terms

PAGB

I

CHAPTER II.

The Plating Room.—Practical Work
Preparation of the Articles * .
Chemicals and Materials

*5
39

CHAPTER III.

Batteries .

Workshop Batteries
Remarks upon Batteries
The Galvanometer .
Dynamo-Electric Machines

47
50
69
72
74

CHAPTER IV
Deposition of Copper . . . * . 82viii

CONTENTS.

CHAPTER V.

Depo&iifcm of Silver

X >

*	«r'

V-;	CHAPTER VL

Depositt$jrpf Nickel

CHAPTER VII.
Deposition of Gold . . .

CHAPTER VIII.

Deposililfi of Aluminium
Deposition of Brass . .
Deposition of Platinum .
Deposition of German Silver .
Deposition of Zinc .

Deposition of Tin
Coloured Coatings for Metals .ELECTRO-

CHAPTER I.

Introductory Remarks.

Electro-plating is the art of coating metals with
metals by mean& pf electricity. Although the term
is only generally applied to the coating of articles
with silver, it is nevertheless quite applicable to the
covering of metals with gold, nickel, copper, or
other metal.

Electrotyping is the second great division of
the art of electro-metallurgy. It means the pro-
duction of copper copies of articles by means of
electricity.

The whole art of electro-metallurgy is based upon
a simple fact—that a current of electricity tends to
decompose a metallic solution into water and metal,
depositing the metal upon any surface prepared to
receive it. Solutions of almost all the useful metals
may be thus decomposed, and the metallic portion
thrown upon a receiving surface. This is the
principle upon which both arts are based—they
i	b*

ELECTRO-PLATING.

owe their existence to the same fact. To plate is
to perfectly clean a metallic surface, and to deposit
the metal thereon, so that it may incorporate itself
with the original surface ; the result is that the
article looks like silver, copper, nickel, gold, or
whatever metal may be deposited upon it. To
electro type is to deposit the metal upon a surface
prepared so that good adhesion cannot take place.
, The result is, that if the depositing is allowed to
go on until a good thickness of metal i$ laid, the
deposit may be removed. It will now have a
separate existence of its own, and its face will faith-
fully represent the surface upon which it was laid.

Electro-plating is thus applicable to the coating
of all kinds of metallic articles, from a needle to a
statue, either to protect the real surface from decay,
or to beautify and ornament.

Electrotyping renders easy the reproduction and
multiplication of engraved steel plates, woodcuts,
set-up type, printing surfaces generally, objects of
art, hollow and solid vessels, coins, and various
other thii%s of more or less importance.

BotH arts are practised to a very considerable
extent in all civilised countries, especially in
England—their birthplace—France, and America.
There are large factories with every necessary ap-
pliance, and unwholesome dens where work is
done by makeshifts, for the prosecution of electro-
plating. The printer and engraver use electro-
- typing, and its applicability is extending daily.
Tops of objects—articles of utility and no use—areINTRODUCTORY REMARKS.	3

made which would not be saleable were it not for
electro-plating. A watch-case of copper is made
to look like gold—for several years—for three shil-
lings ; a chain for two; scarf-pins at as much a
dozen; hair-pins jber gross. Forks and knives,
spoons and liqueur-labels are silvered at threepence
to a shilling each; teapots, coffee-pots, and other
large things at five shillings each.

One woodcut may be copied by thousands in
copper. Engraved plates may be similarly repro-
duced, and the exceeding accuracy of the copy is
such that a practised eye cannot find a difference
between the copy and the original. All printing
faces so produced may be made to last for ever by
thinly coating again with very hard iron (" steel-
facing "), and dissolving this off, with further
plating, when it is worn. Works of the most
complicated design, undercut or plain, hollow or
solid,—statues, large or small,—are produced and
multiplied to any required extent.

By simply immersing articles in, solutions, they
are coated thinly with metals; large articles at
so much each, and small at so much per dozen or
pound.

The art of electro-deposition is still further divi-
sible into several sections. In electro-plating there
is first to be considered the

Solution : it must be composed of a salt or com-
pound of the required metal dissolved in water or
other liquid. It is contained in a vat or pot termed
the depositing vessel. Electricity must be made to4

ELECTRO-PLATING.

-pass througn this solution, from one plate to another.
The plate by which the current enters is called

The Anodey which is in most cases of the same
metal as the solution. This anode (ana, up, and
hodos, a way) not only serves to lead the current
into the solution, but it usually dissolves just as
fast as the solution is robbed of metal, so that an
electro-plating solution is constantly renewed, and
made to last for several years. The current passes
through the solution, decomposes it, and deposits

the metallic part upon the article being plated,
which is sometimes called

The Cathode—from cata> down, and hodos, a way.
The electricity passes out of the liquid by this plate
—teapot, bundle of pins, or whatever it may be-*-
back by stout wire to the

Battery, Fig. i, where the electrical energy required
is generated. A battery, or generating cell, is not, as
is popularly supposed, a complicated chemical com-
bination. A good electrical generator may be made
from a pair of plates, zinc and copper for example,
plunged in soured or acidulated water. A battery

(Depositing Cell.) Fig. i. (Battery Cell.)INTRODUCTORY REMARKS.	5

is a combination of two or more cells—the term
is not properly applicable to one cell only. A
wire stretches from each plate to each end of the
depositing vessel, and is then cleanly connected to
the anode and cathode, or article. This completes
the arrangement, which is applicable either to
plating or electrotyping if the solution is a copper
one. But before anything can be done, the articles
to be plated must be

Cleaned, which means absolute freeing from all
possible impurities by chemical means. This is
spoken of in the following pages under the head of
preparation, which means the cleaning of articles,
whether mechanical or chemical processes are used.
It also includes the preparation of articles to be
copied in copper, making moulds from the same,
and preparing or rendering conductive the surfaces
of such moulds. Under the head of electrotyping
will be found all the necessary particulars, mould-
ing and preparing, relating to it. Preparationy
again, is devoted chiefly to the plating section of
electro-deposition.v

It will prove a great saving of time to the amateur
or would-be plater to make a few experiments with
a solution composed of sulphate of copper dissolved
in warm water. The " battery " may be a copper
and zinc pair, in a teacup full of acidulated water.

A knowledge of the fact that such simple-cells
must have their plates separated for a little distance
by some non-conducting substance, such as wood,
paper, or glass, is also necessary. It will, perhaps,6

ELECTRO-PLATING.

be unnecessary to state that wood and such things
will not conduct electricity, and that all metallic
and most liquid substances conduct it very well.
Metals—silver, copper, and so on—are good con-
ductors ; water not so good, damp wood or wire-
covering poor, and dry wood and such non-metallic
substances are so poor in conductive power that
they are usually called insulators, or substances
through which electricity cannot pass.

A Daniell or Smee generating cell (see Bat-
teries), a pint of silver, gold, or copper solution,
with an anode plate of the required metal, will
enable the amateur to plate small articles, and also
to electrotype in the copper solution. The Daniell
or Smee generating cell will supply the electricity,
a solution the metal, and all that is wanting is a
surface to deposit it upon—permanently if for
plating, and for the time being if for typing. Small
articles, which it is required to coat only thinly,
may be readily plated by simple immersion, or in
contact with a, chip of zinc {see under different
heads). Solutions are described by means of which
simple immersion may be made to give a good
thick coating. Those who wish.to earn their bread
by silvering small articles cheaply, as thousands do
in Birmingham and London, will find those simple-
immersion mixtures very useful. The hot ones are
best suited for rapid and good working. It is of
more importance to very perfectly clean the articles
to be electro-plated, than those to be silvered,
coppered, or gilt, by simple immersion. The onlyEXPLANATIONS OF TERMS.	* J

■ *

guarantee, however, of good work is the most scru-
pulous cleanliness: even tfye finger must hot be
allowed to go near a surface cleaned. In typing,
on the other hand, the face of the article to be
copied need not, and indeed must not, be made
clean if it is intended to deposit upon it direct,
which is seldom done. It is usual in typing to take
an impression of the article in gutta-percha, or
some other substance, and to render the resulting
surface conducting by applying various substances,
more or less valuable in practice. Just as much
care is necessary to make a perfect conducting
surface upon a mould as to clean an article for
perfect plating.

Owing to the fact that this treatise is written for
those who know nothing of chemistry or electrical
science, it is arranged in a somewhat unusual way;
and explanations are given, and language used,
that may, to a great extent, be considered unneces-
sary by the initiated. Explanations of the terms
which could not well be avoided are given, and
their connection, with the work of every-day life
shown. The reader is assured that the practice of
electro-deposition may be carried on with only a
modicum of scientific knowledge.

Explanations of Terms.

To " dilute" means in almost every case to add
water to, or mix with water. Dilute acid means
usually acidulated water. Many mistake the term to
indicate acid to which a little water has been added.8	ELECTRO-PLATING.

To " dissolve" simply means to place the sub-
stance in some liquid by which it will be melted,
and disappear, and the liquid is then

A "Solution." Solutions are usually liquids,
such as water and acids, in which some solid sub-
stance or gas has been dissolved.

To " Digest93 is to dissolve, but it usually means
by heat—that is, the liquid must be heated, to
slowly dissolve the substance, and this is called
digestion.

To " Precipitate" is to throw down any metal or
substance in solution by the addition of another
substance—thus, to precipitate the silver of a solu-
tion as a chloride, add hydrochloric acid or common
salt. The precipitate means the substance thrown
down. Precipitates are usually heavy enough to
fall at once to the bottom; from them the solutions
are then

"DecantedTo decant may mean pouring off,
or it may mean drawing off with a syphon. It is
not unusual then to

Redissolve the precipitate—this, of course, means
dissolving again, but

Precipitate and Redissolve generally mean to
add such an agent as a solution of potassium
cyanide to a solution, and to continue adding it
until the precipitate which is formed begins to
disappear againy by means of the great strength of
the added agent.

Evaporate almost always means to boil the solution
until all the liquid portion disappears in steam, theEXPLANATIONS OF TERMS.	9

Residue or resulting substance being the metal
or substance previously in the solution. This is
driving off all

Excess of acid. Excess here means more than is
sufficient to form the salt or other substance at the
bottom.

Evaporate nearly to dryness means to get rid of
the liquid portion until the liquid left is very thick,
and ready to crystallize on cooling. When direc-
tions are given to	,

Wash the resulting salt, it means that the salt is
not soluble in water, otherwise it would dissolve in
the water. When it is directed to

Wash the precipitate, it means that water is to be
dashed in, the precipitate stirred in it, allowed to
settle, and freed from the water by pouring off or

Filtering, which means that the whole, water and
precipitate, is to be poured on a filter, usually of
calico loosely stretched on a hoop.

Saturated solution, or Saturation, means that con-
dition of a liquid when it cannot dissolve any more of
a substance.

Free acid, or Cyanide. This means that amount
of the cyanide added after the precipitate or sub-
stance is quite dissolved. It me^ns more than
enough to effect the immediate purpose. Free acid
or cyanide in a solution for plating means that
amount necessary to dissolve the anode, or, more
correctly, to form into a salt the metal dissolved
off the anode by the current. It also assists in
keeping the conductivity of the solution good. \10

ELECTRO-PLATING.

Salt means any compound of a metal, usually
that resulting from its dissolution in an acid and
subsequent crystallization. " Common salt" means
chloride of sodium, or common house-salt.

Parts usually means weights and measures; and
where " parts " is used in directing for the make-
up of solutions it means that grains, ounces, or
pounds may be used, or ounces, quarts, and
gallons, according to the volume of solution re-
quired.

Deposit, " depositing/' " coat," " layer," " cover-
ing," mean simply the metal thrown upon any
article or surface by the aid of electricity.

Plating is used here to indicate not only coating
with silver, but with all other metals.

Clean. This is a very important word to under-
stand. As is said in the section on preparation, it
means absolute freedom from all foreign substances,
even a layer of air. Chemically clean is perfectly
clean.

Film means the coating or deposit. In any other
sense its meaning will be obvious.

Amalgamate means to cover with a closely ad-
herent film of mercury.

Quick means to coat with mercury in a solution
of a mercury salt.

Contact: This means electrical contact, or the
completion of an electrical circuit. It means the
parts touched together to complete a circuit, or, in
other words, to complete a metallic path for the
passage of electricity.EXPLANATIONS OF TERMS.	I I

Connection. This means joining a wire or other
conductor to complete a circuit. It means also
that the parts of the metals touched together must
be clean, because electricity will not pass through
dirt. " Connect to " means to join to with wires to
form a proper conducting

Circuit. This means the path or conductor in
which electricity passes. A complete circuit of some
good conductors is necessary, because electricity
must find its way, so to speak, lack to the battery
or other generator after doing the work.

" Work." This usually means the articles to be
plated; again it means the duty performed by the
current of electricity.

"Pole " means one end of a battery. It is usual to
call the copper end the positive pole, while the zinc
is called the negative pole; but in this treatise the
words are not used. Instead, and to save the
possibility of error, I use such terms as " zinc pole,"
"copper pole," "zinc end" "copper conductor,"
" zinc conductor." I also call the copper wire (the
wire leading from the copper) the anode wire, and
the zinc wire the cathode wire or conductor. I also
call the latter conductor, the article wire, about
which there can be no mistake. In reading other
books, the plater will find the zinc plate called the
positive platej but the end of this plate, or its wire,
the negative pole or wire. He will also find the
copper plate called negative, and its end or wire
positive. Although those things puzzle a beginner,
and are seldom explained clearly, a little considera-12

ELECTRO-PLATING.

tion will show that they are perfectly logical. The
current of electricity is generated or set free at the
zinc plate, and instead of passing off by the zinc
conductor, it goes through the solution to the copper
plate, which receives it, and is therefore termed
negative, while the zinc which gave rise to it is
called positive. The current then passes off by the
copper conductor, which leads towards the zinc, and
is therefore termed the positive pole or wire, while
the zinc end, which receives the current from the
outside circuit, properly enough gets negative applied
to it.

" Cell" means a pair of plates in a solution or
liquid; a generator of electricity, such as a zinc and
silver plate in acidulated water. The plates should
be as near together as possible without touching.
Element is the same thing, or one cell of a

"Battery" which is a combination of cells, al-
though the term i$ sometimes, though incorrectly,
used for one cell only.

Join up, means to connect together, either in
series—zinc copper, zinc copper—or in " multiple
arc," which is joining all the zincs to one con-
ductor, and all the coppers, carbons, or silvers to
the other. It also means to connect work so as to
put it

In the circuit, which means to so join the wires
that the electricity must pass through the required
part.

To solder means to clean, wet with hydrochloric
acid saturated with zinc, place tinman's solderEXPLANATIONS OF TERMS.	13

upon, and heat until it runs ajid takes to the metal
to form a perfect metallic joint. Soldering is best
done with a soldering bolt of copper, heated, and its
end cleaned and " tinned " with solder.

Stripping means the process of taking valuable
or other metals off old or badly-plated'goods.

Current means the volume of electrical action, or
force passing, with no reference to its force.

Force of current is more fully explained in the
section on batteries; it means the strength to push
through resistance.

Resistance> of course,, means the imperfect con-
ductivity of the solutions, by reason of which they
resist the passage of all electricity of insufficient
force.

Insulator means that through which electricity
cannot pass, or a very imperfect conductor. Insu-
lated means covered with a very badly conducting
substance—thus an insulated conductor is a copper
wire covered with gutta-percha, cotton, silk, or
tarred hemp.

Conductor means a wire leading the current.
These wires should be of stout copper, and covered
with gutta-percha or other insulator.

Wires are conductors. They should always be
insulated.

To wire is to join the articles by wire so that the
current may pass through them.

Anode means any plate in a solution connected
to the copper or positive wire. Anodes in solutions
are meant both to conduct the current there, and14	' ELECTRO-PLATING.

to dissolve, so as to make up for the metal deposited
upon the

Cathode, which is the article connected to the
zinc wire on being plated.

Galvanometer, an instrument consisting of a coil
of wire with a freely suspended compass needle
therein, for measuring the force of electricity, or
indicating by the swing of the needle its direction
of motion. (See Galvanometer.)CHAPTER II.

the plating-room.

Practical Work.

The plating shop should be well lighted, and
cleanly whitewashed. It should be on the ground
floor, and steam power is a great aid to rapid
and good working. If there are dynamo-electric
machines instead of batteries, they should be raised
three feet from the ground to allow satisfactory
examination of their commutators. Vats should
be placed against the wall, if possible under a
window with a white screen, to be used for strong
sunlight when necessary. Scratch-brushing arrange-
ments, with the cleaning pots, should be at the
other end, and nearest to the door. Gilding being
a part of the business not so extensively applicable
as silvering, nickeling, and coppering, should, on
account of the valuable metal, be done in a more
private room, fitted with gas or other heating
arrangements. Whether for gilding or coppering,
the temperature of the shop should never fall below
45° Fahr. in winter, because almost all solutions
work badly at a low temperature; and if batteries
are kept out of the room, they must not be allowed16	ELECTRO-PLATING.

to freeze. Good ventilation is of the greatest
importance. There should, be a yard or roofless
place in which to do stinking chemical operations,
and a plentiful supply of tap and filtered rain
water.

Heat should be at hand, preferably by means of
steam pipes. Over this heat should be kept iron
boxes filled with boxwood or mahogany sawdust
for drying the articles. An iron boiler, for holding
the hot caustic potash cleaning mixture, should be
out of doors. No cleaning arrangements should
be carried on near to the dynamo-electric machine
or engine. Two tubs should contain dipping
water, and the cleaning and " pickling" and
u quicking " mixtures should be in glazed earthen-
ware pots. Chemicals should be kept upon shelves,
which should be fitted with a dark cupboard for those
things that will not bear exposure to the light.

And finally, but of the greatest importance, there
should be a supply of acetate of iron as an antidote
in case of poisoning by the cyanide liquids so
much used. (See Chemicals.)

Scratch-brushes.—The operation of scratch-brush-
ing is very often spoken of throughout this treatise.
Scratch-brushing means rubbing with fine wire
brushes and some liquid, to scrape or rub off the
impurities on goods before they can be properly
cleaned for plating. The term is also applied to a
similar action with hard hair-brushes, and indeed a
great deal may be done by hard hair and fine sand.
The simplest scratch-brush is simply a bundle ofSCRATCH-BRUSHES.

17

fine wires, usually brass, about an inch in diameter
and five long. It is bound tightly by much stouter
wire, which is wound off as the brush is worn
(Fig. 2).

Scratch-brushes for large and professional
work are always mounted on a lathe-frame,

or in such a way that steam power or the
foot may be used to give a rotatory motion
to them. The brushes are thin circular ones
of brass or iron wire (Fig. 3). For power,
the brush is simply mounted upon a spindle
running in two bearings, a pulley being pro-
vided to take the belt from the shaft over-
head. The lathe contrivance is always a
rough1 framework, with a wheel and treadle.
A hood of sheet metal is provided over the
brush, to prevent its throwing the dirt in Fig. 2.—

Simple

showers about the shop. It is usual to feed Scratch-

x	brush.

the brush with a continuous drip of stale
beer, supplied from a small barrel overhead. There
is also a trough under the brush, and
a drain-pipe to take off the used
drippings (Fig. 4).

Vats for Solutions—Depositing Ves-
sels.—The size of the vat will de-
pend upon the magnitude of opera-
tions. Large vats contain as much
as 300 gallons of the solution, others
150 and 200 gallons. Such vats may F; 3_Rotary
be from three to six feet long, from Scratch-brush.
one to two wide and deep. The actual size, as long

ci8

ELECTRO-PLATING.

as it will hold the articles to be worked upon, is of
little consequence. It is usual to have the long
vats filled with a series of anodes, connected to one
battery, between which the articles are immersed,
so that both sides of them may be equally plated
upon.

Wooden vats without lining used to be employed,
but experience has shown that they absorb much

Fig. 4.—Scratch-Brush Lathe.

of the liquid, and if it is valuable, as silver, the
fault is a great one. For all solutions they ought
to be coated within. Gutta-percha will not do for
cyanide liquids, as they destroy it. Vats made of
wood are best lined with good Portland cement.
But no vat is so good as one of rolled iron plate,
with a lining of thin wood to prevent contact with
the anodes. All the first plating factories have ironDEPOSITING VESSELS.

19

vats, and the best of them are enamelled within,
which makes the vessel perfect, if it is properly
done. Small tanks for gilding made in this way-
are very handy.

, For sulphate of copper solutions a wooden vat
does very well, and it is much better lined with
marine glue or asphaltum cement.

Cyanide liquids, except of course gold ones, which
require to be heated, may be kept in well-jointed
oak tanks, but the wood is gradually destroyed,
and the solutions soak through and run off on the
outside. A wooden tank lined with slate bedded
in cement gives every satisfaction.

For the standard nickel solution a tank of wood
lined with asphaltum cement gives every satisfaction.

Gilding solutions should be in iron enamelled
small tanks, fitted with feet, and with gas-burners,
lamp, or stove beneath ; and a thermometer ought
to be permanently fixed to the tank, below the
surface, so that the temperature may be ascer-
tained at any time, and regulated.

Contact arrangements are best made with stout
brass tubing. Every tank of large size, or which
is to have over one anode, should be well fitted, to
save trouble, with " continuous contact" arrange-
ments. Every tank should, for the same reason,
have a ledging extending outwards. Upon this
ledge the " continuous contacts" are laid. They
are simply two rectangles of brass tubing. One
rectangle goes all round the outside of the ledge,
on the upper surface, and to this the copper or%20

ELECTRO-PLATING.

anode wire is fixed by a binding screw. And from
side to side of the tank extend the anode rods, rest-
ing upon this rectangle of tubing.

Inside this goes another rectangle of smaller
tubing, to which the zinc or article wire is fastened,
and across this rest the three or four article bars
used. These bars should have wooden or gutta-
percha heads, so that accidental contact with the
anode rectangle may be avoided. It will be seen
that the arrangements are of a very simple de-
scription.

The brass rims and rods must be kept clean
throughout their lengths, and for this purpose
emery-cloth should be at hand and used every
morning. It is a great improvement to gild the
rods, which will render the cleaning unnecessary,
unless extreme carelessness is used. It is a good
plan to have a slit made in the wooden rim, be-
tween the rectangles of tubing, and the edges
sloped off to it, but no iron or other metallic con-
tacts may, of course, come between the rods or
tubes. This slit will carry off any liquid that may
be by accident spilt upon the ledging. Such parts
should be kept dry, because a layer of liquid con-
necting the tubes or rods will " short circuit" most
of the current, and send it back to the battery
without passing through the liquid. Arrangements
may of Course be, and are, adopted to prevent any-
thing of the kind, such as wooden corner supports
for the larger rectangle of tubing.

For smaller tanks or vessels, such as are usedPREPARATION OF THE ARTICLES.	21

for gilding, it will be unnecessary to provide con-
tinuous contacts, because one anode is usually
enough. A pair of rods with wooden ends, for
resting upon the tank to quite prevent contact,
will be enough. They should have binding screws
fitted to them, and from them should hang, by stout
hooks, the anode and batch of articles being gilded.

Operations on a still smaller scale need not in-
volve the providing of rods. The anode may be
simply hung from the copper wire, and the articles
from the zinc wire. This is applicable to small
working in porcelain vessels. A great deal of good
gilding is done in such things as large battery pots,
heated by being kept in boiling water in an iron
pan, glue-pot fashion, and no other arrangements
are employed.

In all cases where the anodes are over six inches
square, they should be provided with two silvered or
gilded hooks to hang evenly upon the cross-rod.

It is very convenient to have a let-out tap fitted
to tanks two inches above the bottom, for letting
off liquids; but some platers would prefer to employ
a syphon of lead tubing, and draw off from the top.

Preparation of the Articles.

v I cannot impress too strongly upon the beginner
the importance of properly preparing the articles
before plating them with any metal. We must
have chemically clean surfaces. Ordinary cleanliness
is of no use whatever.

To sum up the causes of failure in almost every22

ELECTRO-PLATING.

instance of bad work in one word, is no difficult
matter—that word is dirt. No matter how clean a
surface may look, it is in most cases dirty, and if it
is not dirty, there exists upon it a film of air, which
will effectually prevent good coating from being
done. It is to the plater absurd to suppose that,
because the amateur cleans his watch-chain with
whiting, it will take a coating that will stand heat-
ing or burnishing. Common cleanliness causes
the work to be a failure, because, if there is not
an invisible coating of oxide or dirt, there is one of
air, which must be removed effectually before any-
thing can be done. It is a very easy matter to
obtain a deposit over the surface, but quite a different
matter to lay one that will stand burnishing and
heating. It is, moreover, important in good work
to make the surface smooth.

The mode of operation in cleaning will depend
upon the nature of the article, and its condition.
To " rough clean " the surfaces when they are very
dirty, a hard hand-brush, with silver sand and water,
will prove useful. After this, as a rule, the, article
should be well scratch-brushed to clean and smooth
the surface, but small articles of silver may be
brushed with a tooth-brush and rouge, whiting,
rotten-stone, and other cleaning powders, until the
rough and dirty superficial coating is cleared off.
Articles that appear perfectly smooth and clean
will, in most cases, have a slightly greasy surface,
which must be cleaned off by rinsing in boiling
caustic potash solution.PREPARATION OF THE ARTICLES.	23

Rough, and coated with Oxide.—Scrub off with
hard brush, sand and water, emery-cloth, scraper,
fine file, or wire card, according to the size and
condition of the articles—this applies to old articles.
After finishing the surface with the scratch-brush
and stale ale, burnish if required, and treat as
hereafter directed.

Burnishing.—This is rubbing in straight lines
with a finely polished hard steel tool, long, and of
oval section. Burnishers of other materials, such
as dogs' teeth and agate, are also employed. Bur-
nishers are made for different purposes; for large
work, to be fixed in the vice, the burnisher is an
oval bar of hard and finely polished steel, about a
foot long, and having two handles. For work re-
volving in the lathe, the burnisher is a rounded
head upon a steel shank; the head being finely
polished is pressed upwards upon the work, and
moved from end to end of it. With brass this is
done dry, but with copper and iron a little soap
and water will be found useful to prevent the tool
from cutting up the work. For hand work nothing
is more suitable than the ordinary watchmakers' or
jewellers' long burnishers, costing a few pence.
All these tools must be kept brightly polished by
rubbing in straight lines upon the finest emery-
cloth. The operation of burnishing is not learnt
at once, it needs attention and practice. The
surface must be previously prepared, by scratch-
brushing, or fine draw-filing, or rubbing in straight
lines with emery-cloth, and then the burnishing24

ELECTRO -PLATING.

may be done* The work must be held firmly, and
soapy water used, if the tool begins to grate upon
the work. Burnishing is also done to the coatings
after they are laid, if a polished appearance is re-
quired. But it should be remembered that the
best electro-plate, whether nickeled or silvered, is
not burnished, except to ornament prominent parts.
The work is polished and buffed, that is, scratch-
brushed, and then dried and held against a re-
volving buff, or softly covered wheel, making use
of such powder as fine jewellers' rouge. A first-
rate buff may be made by placing a great number
of fustian discs, cut circularly and pressed against
a flange mounted upon a spindle—a wheel, in short,
of discs of cloth. Hand buffing may be done with
wood sticks covered tightly with two layers of
wash-leather or fustian, employing rouge to polish
with. Rough cutting materials must not be em-
ployed to clean electro-plated surfaces.

Manufactured Goods.—These are the articles as
they come from the maker's hands, clean appa-
rently, but covered with a greasy film. They must
be rinsed in the boiling caustic potash liquid, and
then treated like others by dipping in various
cleaning mixtures, of which particulars are here
given.

Scoured, and luffed articles of silver are to be
rinsed in diluted nitric acid, dipped for a moment
only in strong acid, swilled in water, and at once
put in the plating vessel. Great care must be taken
not to touch any cleaned surface with even one finger ;PREPARATION OF THE ARTICLES.	25

if this is done, the deposit will not adhere to the
spot.

Copper, German-silver, and brass, of which metals
the greater number of things are made, are to be
prepared for the bath, after scratch-brushing, by
immersing in a pickle made by mixing together,
half a gallon of each, water and sulphuric acid,
a quart of nitric acid of ordinary quality, and two
ounces of hydrochloric acid. It is wise to have
at hand two vessels of this cleaning mixture ; one
quite fresh for the final dip before swilling in water
and placing in the vat, and the other in which to
first dip and clean the articles. The articles should
be kept for a minute or so in the first liquid, and if
necessary rubbed with it by a pad of cotton on a
stick. The final dip is only momentary. A rinse
in water finishes the work, which must be instantly
placed in the depositing vessel. If articles are
allowed to dry, they must be again dipped, or if the
fingers touch them the same treatment will be
necessary. All articles must have the suspension
wires fixed to them before dipping.

Steel and mw articles, after scouring, are to be
cleaned in a mixture of a pint of sulphuric acid, an
ounce of each nitric and hydrochloric acids, in a
gallon of water. The articles are to be left in the
solution for some time, and if exclusively for steel,
the mixture should be weaker.

Tin, lead, pewter, and Britannia metal are to be
cleaned by rinsing in the caustic potash solution,
swilling in clean water, and at once put to plate.2 6

ELECTRO-PLATING.

To make up the caustic potash solution, place in
an iron boiler four pounds of caustic lime, add
water with stirring until a creamy mixture is pro-
duced. Then stir in a solution composed of eight
pounds of pearlash in hot water. Boil the mixture.
If an exceedingly strong caustic alkali is required
for extra dirty work, dissolve stick caustic potash
in hot water. Care must, however, be taken to
keep the naked skin from this material, because it
produces exceedingly bad sores, which are difficult
to heal. It will, in fact, dissolve the skin quite
readily. (See Chemicals.)

Britannia metal, zinc, tin, and pewter should not
be dipped in acid mixture, because they dissolve
therein very fast. As soon as the "dipping" is
done, it is best to have at hand either a stream of
water, or watet in two pots, so that the articles may
get a washing and a final dip before placing in the
depositing vessel. A great many of the articles
have, however, to be dipped in a " quicking " solu-
tion to get a coating of mercury, to secure adhe-
sion. (See Quicking,)

Cast iron, with the original " skin," is usually
exceedingly hard, owing to a glaze of iron silicate.
It is often treated with hydrofluoric acid—usually
called " fluoric acid." This will dissolve the silica,
but the greatest possible care is necessary in hand-
ling it, as it will not only destroy the human skin
and make bad sores, but it will dissolve glass ves-
sels, and must therefore be kept in a gutta-
percha or lead bottle, closed with a stopper ofPREPARATION OF THE ARTICLES.	2 J

gutta-percha. Its fumes should be avoided as
much as possible. It is usually employed for
glass ornamenting, and lettering upon "flashed"
glass.

In all the operations it is best to have at hand a
strong cleaning solution, a medium one, and a
" spent/' or weak one, and then two pans of water
for final dipping. The solutions are called " dip-
ping liquid " for the strong, and " spent liquid" for
the weak. Nitric acid, used chiefly for silver, is
called aquafortis when in the strong state, and when
^weakened by repeated dipping, " strong pickle ; "
the second quality or strength of this being called
" weak pickle." Pickle is also frequently applied to
sulphuric acid water, into which things are thrown
after heating. Small bulks of the liquids never work
well. They should be contained in large earthen-
ware pots, well glazed ; the caustic potash liquid in
an iron vessel over a fire. Caustic potash is employed
to clean off greasy surfaces, and the acid mixtures
are usually made up to dissolve films of oxides, and
to clean up or expose the real surface. It may be
often unnecessary to scour or scratch-brush the
work. The acid mixtures may do the cleaning
throughout. Copper and German-silver are very
often heated to dull redness, and then thrown into
sulphuric acid pickle, which will cause the scale to
fall cleanly off, when a final dip and wash will
render the work ready for plating upon. Articles
that are soldered with tin solder must not be so
treated, because it would cause them to fall to28

ELECTRO-PLATING.

pieces. Silver may also be heated, and thrown
into hot dilute sulphuric acid. Zinc may frequently
be dipped in strong pickle—dilute sulphuric acid.

"Dipping acid/' or nitric acid mixed with sul-
phuric, is sold at a cheap rate.

For coppering the cleaning itself will be sufficient
to insure an adherent coating, but for silvering and
gilding it is wise to employ the method of coating
with mercury.

Quicking Articles.—The mercury solutions are
easily made up and kept in order. For copper,
brass, and German-silver make a solution as fol-

»

lows :—Prepare about a pound of nitric acid diluted
with three times its volume of water. Pour this
upon an ounce of mercury, a little at a time, with
stirring, until all the metal is dissolved. The action
will be somewhat slow, but no more acid than is
necessary is to be added. Dilute the whole with a
gallon of water. Zinc articles are best coated in a
solution made up in this way Dissolve an ounce
of nitrate of mercury in two gallons of water mixed
with four ounces of sulphuric acid. To make aquick-
ing solution of cyanide of mercury in potassium
cyanide:—Dis,solve the mercury in dilute nitric acid;
make up a solution of cyanide of potassium one
ounce to the pint, and add it to the mercury solu-
tion, with stirring, until the metal is precipitated as
cyanide. Allow to settle, and pour off the liquid
portion; wash with clean water, pour off, and add to
the precipitate with stirring enough cyanide solu-
tion to dissolve it. Dilute the whole to the ex-PREPARATION OF THE ARTICLES.	29

tent of one ounce of mercury to a gallon and a
half.

It is important that these solutions contain only-
enough mercury to give to the article the thinnest
possible coating; a thick coating will cause the
metal to strip after the plating is done, which is an
exceedingly vexatious result. Too little, so long as
the surface is perfectly covered, cannot possibly be
put on, but too much is easily laid. A good test of
a quicking liquid is to immerse in it a piece of
clean copper plate. If the plate becomes white
very soon, with a thin, closely adherent coating,
the liquid is right. If the coating is black, or bad
in colour, the liquid is not properly made, or is
exhausted. It is important that all the articles
look uniformly white on removal from the quicking
vessel. If they are patched, the surface is either
greasy, or the solution badly made. A good coat-
ing will insure that a perfectly reliable molecular
contact will take place between the plating and
the article, which will stand burnishing or other
usage.

Preparing Iron for Silvering and Gilding.—It
would appear quite impossible to lay either gold
or silver in good molecular contact with an iron
surface, no matter how perfect the cleaning may
be. A good deal of plating with silver has, how-
ever, been done upon iron direct, but the work is a
botch at the best, because the metal will strip off
very easily, and will not stand burnishing. On
cutting under such a film, the metal may be scaled30

ELECTRO-PLATING.

off with the knifey disclosing an iron surface far
from good in colour. However it happens, the
surface is of a bluish oxidized tint, although on
placing in the bath it was perfectly clean. This
tint seems to take some time to develop, because
it is seldom found directly after plating. The only
remedy as yet practically applied is to deposit a
thin coat of copper upon the iron previously to
gilding or silvering. Iron " takes" copper per-
fectly in a cyanide of copper solution. (See Copper.)
The copper should not have any appreciable thick-
ness, but must perfectly cover the iron.

Stopping off.—This is the prevention of a deposit
from spreading all over an article when only half
of it is to be plated. Melted solid paraffin is very
useful in cold liquids, acid or alkaline, because it
is not affected. Sealing-wax varnish may be used
in liquids not too hot. Copal varnish is, however,
more suitable for hot liquids. The best copal
varnish, with an admixture of fine jewellers' rouge,
will prove useful in extra hot liquids. (See Gold.)
Various cheap substances may be used for large
surfaces, but they must be fairly thick, and should
be capable of being easily dissolved or melted off
after the work is done. Engravers' wax may be
used, also tallow, bees'-wax, shellac varnish, and
such substances' easily got rid of. Pitch or tar is
not fit for the purpose. Surfaces not to be deposited
upon should, if possible, be kept turned away from
the anode, or exposed to its influence as little as
possible, because deposits actually do take placePREPARATION OF THE ARTICLES.	31

upon thin varnishes if the current is strong. This
is a waste of metal.

Dipping, for "Bright" and"Dead" Gilding.—This
appearance is chiefly applicable to copper, brass,
and German-silver. Dip in weak nitric acid until
the surface shows a black scaly appearance, then
immerse in " strong pickle "—very weak nitric
acid. Then plunge into strong nitric acid and
quickly wash, and put in the plating vessel. It is
more convenient, when there are many things to
do, to provide for " bright dipping " a mixture of
exhausted nitric acid, half a pound; water, one
pint; hydrochloric acid, three pounds. It is suited
to the general run of metals, copper, brass, and
German-silver. They are to be soaked for a few
minutes in it, after which they should lo.ok bright
on cleaning off the black slime covering them.
Such articles may be again prepared for the bath
by rapid and effectual washing.

" Dead" dipping is usually done in a mixture of
one pound of sulphuric acid, and two pounds of
ordinary commercial ("yellow ") nitric acid, with the
addition of two ounces of common salt. Soak the
articles in the mixture until "dead," remove and
pass through the pickles, then through two waters
to the plating vessel.

In all the processes of dipping to impart chemical
cleanliness of surface, small articles, or such as are
fitted for it, should be strung upon a wire in
bunches, or in stone vessels (Fig. 5), so that they
may be shaken about in the vessels. The same32

ELECTRO-PLATING.

wire should hold them in the gilding or silvering
vessel, and such wires should be already gilt or
silvered to prevent loss of contact. Batches of
spoons and forks should be done at once, strung
upon a suitable wire by hooks made to slip over
their stems.

" Wiring" the Articles.—Small articles for gild-
ing are to be strung upon a tliin gilt wire if they
admit of this being done, and if not, they should be
placed in a stoneware basket, and
shaken about constantly while in
the gilding liquid. The contact is
got by wiring only one of the
articles to the article-rod of the
vessel, but almost all kinds of
small goods may be wired in
batches : if this is done they must
be arranged loosely, and constantly
shaken while being gilt, otherwise
they may only be partially gilt,
and the colour may be bad. (See
Gold.) Larger articles should be
hung by stouter wires separately, and in order that
such wires do not receive a deposit also, they are
bent into suitable hooks at their lower ends, and
covered with a tube of good india-rubber. Varnish
will not do for the reason stated before—that metal
will be thrown upon thin coatings, attracted by the
metallic conductor within. These tubes should fit
the wires tightly, and bundles of such wires should
be at hand, with ends turned into all kinds of hooks

Fig. 5.—Dipping Ladle
and Basket, of Stone-
ware.PREPARATION OF THE ARTICLES.	33

and loops, to suit the standard work doing. All such
hooks ought to be gilt top and bottom, to insure
good contact with the article-rod and articles.

For silver-plating, the same hooks covered upon
their stems, should be at hand, especially those with
right-angle loops at their lower end to take in spoons
and forks. Those loops should again be made in
different sizes, to suit from salt-spoons to tea-spoons
through dessert size to dinner spoons and forks,
the stems of which may be reckoned alike. Small
articles must not be immersed in close
bunches as in gilding, because the opera-
tion of silvering is much slower, and it is
difficult to give motion to them so often.

They should be strung upon a wire—a
thin one, apart, and if possible between
two anodes. Various arrangements are
in use called " slings,"'' loops," " sockets,"
and "swivels," and no difficulty is usually
experienced in the operation of wiring
in silvering solutions (Fig. 6). For nickel- Kg. 6—sung-

. . .	Loop.

mg the wiring is the same as for silvering.

Wiring for copper deposition is in great part
described in the section upon electrotyping. For
ordinary plating with copper, the "slings" and
"loops" need not be coated with gutta-percha,
because the metal is not so valuable, but the
slings may become too stout in time with deposited
copper.

Motion in Solutions.—In gilding, silvering, and
nickeling solutions, having the articles in motion

D34

ELECTRO-PLATING.

is a very great advantage. A very slight motion
will suffice, and it is best to have it up and down,
or parallel to the anode face, across the vat. In
establishments with steam power the vats are
usually fitted with a frame, carrying the rods from
which to suspend articles. This frame is upon four
wheels, moving for a short space upon rails fixed
upon the vat edges, and motion is given from an
eccentric upon the shaft. But a simpler plan is to
make use of a roasting-jack, which may be employed
if the articles are between two anodes, or even
opposite to one another. A frame, hung upon cords
and moved by mechanical means, is also in use, as
are heavy pendulums and other obviously appli-
cable pieces of apparatus. Motion at intervals may
be given by the hand.

Position in the Solutions.—Vertically tinder the
anode surface is the scientifically correct position
for articles being plated. This would hold good
could we procure and work anodes and solutions
perfectly pure, but the common impurities of all the
metals and solutions, accidental or intrinsic, prevent
any such position from being applicable in practice.
If we arrange a flat surface to be deposited upon
horizontally below the surface of the liquid, and
also arrange the anode horizontally over it, a few
inches off, the deposition will go on very steadily,
but on examination the deposit will be found rough,
dirty, and mixed with large spots of impurities
fallen from the anode. All metals are alike, except,
perhaps, pure gold ; and in gold-plating the work isPOSITION OF THE ARTICLES.	35

done so fast that the positions indicated would not
do in practice, while the work must be examined
now and again.

A good plan, however, is to plunge the articles
deeper in the solution than the anodes, and the
plates may be inclined ; but, speaking plainly, and
as a worker looks at the question, it is a case where
" the game is not worth the candle." Even although
the scientifically correct method could be employed,
which is doubtful, supposing the non-existence of
impurities, only a very little less battery power
would be needed, and although the deposit would
be, perhaps, mathematically correct in thickness all
over the surface, very little would be gained, and it
is fairly clear that any advantage would be more
than outweighed by the loss of time in securing it.

Suppose, for example, that there is only one
anode, and that both sides of the article—a salver
—are to be equally plated, it is clear that the plate
must be turned occasionally in the course of silver-
ing, otherwise the deposit must be uneven—more
upon one side than upon the other. The metal
ahvays goes fastest upon that point or side next or
nearest to the anode. Therefore, knowing this, an
intelligent plater will so arrange his anode surface
that the work may be done equally upon all parts
of the article. Anodes may sometimes have to be
bent—convex to suit a concave article, and con-
cave to suit a convex one. This is especially so in
electrotyping, where all shapes of anodes must be
used upon uneven surfaces to secure uniformity of36	ELECTRO-PLATING.

deposition. Large anodes, bulks of liquid, and cur-
rents deposit more evenly than small ones, where
more care is necessary to produce good work.

Faults and Failures.—The operator should always
learn first to deposit copper properly, because the
metal is easily worked, and because it is cheap
enough, and affords a guide to the best methods in
dealing with silver, nickel, and gold. Dirt is, after
all, the chief cause of failure. It is a compara-
tively easy matter to deposit a metal simply, but
to lay it in molecular contact is quite another.

There is such a thing as lad quality of deposit,
and the directions that are here given aim at
placing in the operator's hands such rules as may
prevent the deposition of brittle or porous metals.
With regard to brittleness it may be remarked that,
as a general rule, the result of battery power inade-
quate to the work doing is a brittle deposit, accom-
panied, in the case of silver and nickel, by a
peculiar brightness of surface, and in gold work by
a very pale yellow. Too much current, on the other
hand, will usually produce a porous deposit, and if
the current is very much too great, the metal may
be thrown down in grains.

Scratch-brushing is to be resorted to in the best
nickeling, silvering, and gilding after the first coat
is laid. This * tests its adherent qualities, and re-
veals defects otherwise scarcely discoverable. It
is only true economy of time and material to at
once proceed to strip and re-prepare an article
upon which the first coating is bad. It is seldomFAULTS AND FAILURES.

37

that good nickeling or silvering can be done with-
out at least one scratch-brushing and rewashing
after the first film is on, and before the main deposit
is laid. The same process is resorted to if the
work in electro-gilding is to be well done. Care is
necessary that the metal may go upon all parts of
the surface with the same thickness. Any irre-
gularity of this kind cannot be detected by weigh-
ing, but it may be quite prevented by care in
arranging the anode surface to the work being done.

Although the text-books speak of the exact
equivalent of metal being practicable in electro-
deposition, it is nevertheless almost an impossi-
bility in batteries to dissolve a pound of zinc and
get a pound of copper in the vessel. Trials for
absolute work in this way will fail, because the zinc
is never pure, and the arrangements are imperfect.
To work scientifically in the art is scarcely in the
power of every plater, although a knowledge of
the subject of electrolysis would prevent a great
many failures.

Preparing " Old Work"—Old work is plate
which is very much worn, exposing the real surface
largely. To make a satisfactory finish on such
work without completely removing the old plating
is impossible. A great deal of such old plate is
scoured clear with the scratch-brush and rotten-
stone, the " scratchings " being kept for subsequent
reduction and recovery of the metal; but as a rule
it is both quicker and cleaner to remove old metal
by acids and other means. Scratch-brushing is38	ELECTRO-PLATING.

only applicable to smooth surfaces, cut work being
defaced by having its edges removed.

To remove Silver from Copper, Brass, and German-
Silver,—Prepare a sufficient volume of strong sul-
phuric acid to cover the article, stir in a little
nitrate of soda (half an ounce to the quart of acid),
and heat. Immerse the article, and if the action
becomes weak before the silver is removed, apply
more heat and saltpetre. Copper works best in
this mixture, and it ought not to be exposed to the
acid longer than is necessary.

To remove Gold from Silver it is usual to heat to
redness, and to then throw into dilute sulphuric acid,
when the gold will peel or fall off easily.

To remove Copper from Silver.—Immerse the
article in a hot solution of perchloride of iron, to
make which dissolve jewellers' rouge in warm
hydrochloric acid to saturation; or simply immerse
for a sufficient time in boiling dilute hydrochloric
acid. Perhaps the best way to remove copper
from silver and gold is to make the article the
anode in a sulphate of copper solution.

To remove Tin and Lead from silver or gold,
employ the hot solution of perchloride of iron, which
will also dissolve copper.

Recovery from such solutions is generally effected
by evaporating to dryness and fusing the deposit
with soda (for gold). It is best to dilute silver
solutions, and to precipitate the metal by stirring
in hydrochloric acid.

Some platers practise the replating of old workCHEMICALS AND MATERIALS.	39

without taking off all the old coating, but the work
is poorly done. It is often required to plate evenly
over soldered seams. To prepare such seams, tie a
pair of thin wires to a camel-hair pencil; let their
ends dip down and follow the hair at a short dis-
tance over the work; the brush should be dipped
in strong solution of copper sulphate. Copper will
be deposited upon the seam, or if the solder contains
much tin, it will plate by simple immersion.

Chemicals and Materials.

(.Alphabetically Arranged.)

Accidents.—Cyanide of potassium is a deadly
poison. If any of its solutions or any of the cyanide
plating liquids are swallowed, there is little hope
of recovery for the sufferer; death usually follows
immediately, especially if the mixture is a strong
one. For cyanide of potassium, or any of its
solutions or mixtures, give a dilute solution of
acetate of iron in large draughts, and allow the
coldest procurable water to pour upon the head
and spine. For any of the ordinary acids swallowed,
the sufferer should be given tepid water, to induce
vomiting, and for the same reason the throat should
be irritated inside with a feather. Milk, chalk
and water, and the whites of eggs are also useful in
such cases. If any of the powerful alkalies have
been swallowed, such as soda or potash, give
vinegar, the juice of lemons, or very dilute sulphuric
acid (1 to 100). The greatest care should be taken
in plating factories. It is noteworthy that very40

ELECTRO-PLATING.

few serious accidents are on record, although a
vast quantity of plate is turned out daily. The
naked hands should not by any pretence be put
into cyanide liquids, because the skin absorbs the
poison. If there is a break on the skin, this is
especially to be observed. A pair of long tongs
should be at hand for recovering articles that have
fallen to the bottom of the vat.

Carbonate of Sodium,—This substance is the com-
mon washing soda in every-day use. It should be
kept in a closed vessel, because on exposure to the
air the crystals lose their water and fall to a white
powder. Best quality is. 6d. per lb.

Carbonate of Potassium.—A very common sub-
stance, and often used. It is also called "pearl-
ash." To be kept in closed vessels, iod. per lb.

Caustic Lime.—This is the common "lime," or
" stone lime." It should be kept in closed vessels
in a dry place, as it is apt to absorb moisture and
swell. A good quality is of a clear white colour,
turning creamy on mixture with water. The hands
must not be put into the slacked lime.

Cyanide of Potassium.—A most important sub-
stance, and used in large quantities in making up
the chief solutions, and in numerous other opera-
tions. I shall, therefore, speak of it at some length.

The most important particular to become ac-
quainted with is that its quality varies to a wonder-
ful extent. The common varieties contain only a
small percentage of the actual cyanide, the rest
being salt of potash, quite foreign to pure cyanide{ CHEMICALS AND MATERIALS.	41

of potassium. The poorest quality is known in the
trade as " black" cyanide ; it is pure rubbish, and
should not be used in any process whatever. Then
comes the usual white cyanide. The quality of
this substance varies from fifteen to ninety-eight per
cent, of the pure cyanide. It is not uncommon for
chemists to call their cyanide "pure," when it
scarcely contains 50 per cent, of the article in ques-
tion. The price is no criterion of its quality, because
cyanide of 50 per cent, is sold at prices ranging
from 2s. to 8s. per lb., and sometimes the material
is procurable as good as 96 per cent, at 5s. per lb.
The salt crystallized costs much more; but crystal-
lized cyanide of potassium has no special advantage
over the usual cake or stick varieties.

On account of the variable quality, cyanide of
potassium should always be tested before purchasing
in quantity. To test a sample, the method recom-
mended by Glassford and Napier is very useful:—
Prepare two solutions, one of cyanide and the other
of nitrate of silver. Dissolve 1 oz. of cyanide so as
to measure in a graduated vessel 6 oz. Dissolve
175 grains of the pure silver nitrate in oz. of
water. Stir the cyanide solution slowly into the
silver one until a precipitate is thrown down and
then redissolved. The amount of the sample re-
quired to do this will at once show its quality, for
it takes just 130 grains of pure cyanide to produce
the effect. From the quantity used it is easy to
calculate the quality of the cyanide. There is no
better test than this when the water is distilled4 2

ELECTRO-PLATING.

and pure, and the nitrate of silver the pure crystal-
lized variety. Never purchase cyanide of potassium
of a lower quality than 50 per cent. Solutions
made from poorer salts are not to be recommended.
Throughout this little work the salt is often spoken
of, and the impracticability of giving exact figures as
to its quantity pointed out: most of the directions,
however, indicate the quality as nothing under 50 per
cent. If it is better less may be added; if poorer,
more—but so much the worse for the solution.

It is but fair to mention that I experience much
difficulty in obtaining in any quantity, at a reason-
able figure, a cyanide of 96 per cent, purity in Paris
or London, and that I have had no difficulty in
obtaining almost quite pure (98 per cent.) cyanide
from the firm of Mawson and Swan, manufacturing
chemists, Newcastle-on-Tyne, at 7s. per lb. To
produce such a quality requires the exercise of the
best skill, experience, and attention. The very
best cyanide procurable is icpure llack cyanide"
(not the rubbish spoken of before). It is not easily
obtained, and care must be taken to mention its
purity, with the particular that the black colour is
imparted by an admixture of carbon in the manu-
facture. Cyanide of potassium is also called prus-
siate of potash. It is easily made, and I therefore
give particulars for this purpose.

The common ingredients are ferro-cyanide of
potassium ("yellow prussiate of potash") and
carbonate of potash. Crush the ferro-cyanide, and
expose it to heat upon an iron plate until it is dried,CHEMICALS AND MATERIALS.	' 43

and a white powder is the result. Take also car-
bonate of potash and dry similarly. Weigh out
eight parts of the ferro-cyanide and three of the
carbonate, mix, and add one-and-a-half parts of
powdered charcoal. Bring a clean iron pot or
crucible to a red heat, and slowly put in the
materials until they are all fused perfectly to-
gether. Stir with a rod of iron, and keep the pot
covered as much as possible during the twenty
minutes required for fusing properly. As soon as
all gas appears to have been given off by the liquid
mass, take the pot off, allow to stand a minute, and
pour its contents slowly upon a plate of iron or a
slab of stone. Break up when cold, and bottle at
once.

Hydrochloric Acid.—This is the common " spirit
of salt" or " muriatic acid." It is easily obtained
nearly quite pure. It should be clear,„ unless the
colour arises from dissolved dust. Its price is
usually about 4d. per lb. The specific gravity of a
good kind will be 1 • 16. It may be had of extremest
purity at is. per lb.	*

Hydrocyanic Acid.—This is water in which is
dissolved a certain amount of hydrocyanic acid
gas. It is usually very weak. " Scheele's " is the
strongest, and contains as much as 6 per cent. Jt
must be kept in an opaque bottle. The gas is also
called " prussic acid/' and is well known in medicine
under that name. Care must be taken never to
inhale it, whether arising from the liquid, or from
vats of liquid being evaporated. It is usually44

ELECTRO-PLATING.

better to make use of good cyanide of potassium
in strong solution.

Mercury.—Much of the common mercury contains
lead. Obtain of good quality, and if it is sus-
pected, keep it in a bottle for an hour or two, with
occasional shaking and dilute nitric acid over
it. Bad mercury does a great deal of harm in
batteries. There* should be no drossy appearance
in a vessel containing mercury. It may be cleansed
of superficial impurities by passing through wash-
leather. Its price varies exceedingly. It is also
called " quicksilver."

Moulding Materials.—(See Deposition of Copper.)

Nitric Acid.—This is the "aquafortis" of com-
merce. It is somewhat difficult to obtain it quite
pure. For dissolving silver it should be colourless,
and have a specific gravity of 1*420. For Bun-
sen's cells it should be strong. Its price in small
quantities is about is. per pound; in Worcester
quarts, at 25 per cent. less.

Sulphuretted Hydrogen.—This gas is prepared by
placing some sulphide of iron (" sulphuret of iron ")
with diluted sulphuric acid in a flask. The gas
comes off, and should be washed by passing through
water. A small quantity of water should be used,
and if a solution of the gas is required it is obtained
by again passing into water.

Sulphuric Acid.—This is in constant requisition
by the electro-plater. It is also called u oil of
vitriol/' It is, when pure, much heavier than water,
having a specific gravity of 1*84, and an oily ap-CHEMICALS AND MATERIALS.	45

pearance. It should be clean, because, although
bad colour may simply be dissolved straw or other
matter of no consequence, the acid may be of poor
quality. To test for arsenic, pass through it a
stream of sulphuretted hydrogen, when a yellow pre-
cipitate will indicate the presence of arsenic.
" Dilute sulphuric acid" usually means acidulated
water only—that is, one part acid to twenty of
water. Stronger mixtures than this are particu-
larised as to quantity. Its price is about is. per
pound, pure, in small quantities, and in Worcester
quarts 25 per cent. less. The commercial acid, in
carboys, can be had at 2d. per pound, or 3d. in
smaller quantities.

Syphons.—These are usually made from a piece
of lead piping. They may also be of gutta-percha
or glass. Before use, they should be filled with
the liquid to be drawn off, the ends closed with the
fingers, and the shortest end plunged in the liquid.

Thermometers.—Those with japanned tin scale,
made for baths, are very useful. Their price is
about is. 6d. The "Milk scale" ones are better
when it is required to have the instrument per-
manently in the vat. Their price is about 3s. 6d.
Those graduated on the stem are higher in price
—5*

Twaddel's Hydrometers.—These are very useful;
their price is from is. 6d. to 2s. 6d. They should
be in a set of three, and suitable for testing the
specific gravity of light liquids, such as aqueous am-
monia, and heavy liquids, such as sulphuric acid.46

ELECTRO-PLATING.

Besides these there should be at hand a supply of
test papers—neutral tint litmus, or red and blue
litmus. Filtering papers : these are discs of paper,
put up in hundreds and of different sizes. They are
used in funnels by doubling them twice at right
angles, opening one of the folds and placing on the
funnel. This is usually too slow for the filtering of
large bulks of liquids. Larger ones may be made
of good dlose calico, fastened on a ring of wood or
iron. To filter alkalies or strong acids plugs of
asbestos are usually employed to stop the necks of
funnels. A Galvanometer is very useful ; get one
with two circuits.

Purchase of Articles and Chemicals.—Never pur-
chase such things as earthenware wash-pots of in-
strument dealers if they can be had from the makers.
(See the " London Directory/') Do not purchase
batteries if they can be made properly at home.
Always deal with some well-established house for
chemicals, and unless you know good and bad,
leave the qualities to your dealer—except in the
case of potassium cyanide. Buy valuable metals
from the refiners, and do not use gold coins. Pur-
chase, acids especially, in large quantities at a
time, and thus save money. It will be found best
to purchase the distilled water required, but it will
seldom be used if there is a supply of filtered rain-
water. Compare prices before paying away money,
and compare goods before buying in any quantity,
or to any considerable extent.CHAPTER III.

Batteries.

Electric Generators for Amateurs.—I devote a
portion of my space to descriptions of galvanic
generators specially suited to the wants of ama-
teur electrotypists and platers. It is not without a
certain conviction that such information is much
sought for, and put to use when obtained, that I
approach the matter at all. It will also be fairly
well known that I should be well acquainted with
the general amateur and his wants in this particu-
lar direction, when for three years I have answered
his almost numberless questions in the pages of
Design and Work.

For Nickel Plating employ the Bunsen cell, with
instructions given under Workshop Batteries.

For Silver Plating one Bunsen cell will usually
be enough, except where the need for a high tension
current is indicated. (See Deposition of Silver,)

For Gilding.—A cell composed of a plate of
carbon and another of zinc, clamped to a cross-
piece of wood and dipped in a solution of bichro-
mate of potash, acidulated slightly with sulphuric
acid, will do very well for gilding. If the work48	ELECTRO-PLATING.

takes over a few minutes to do, the plates should
be moved up and down in the liquid to give it some
circulation. The same pair of plates will serve if
dipped in a solution of sal-ammoniac, or if the
articles are very small, in common salt solution.
No binding screws are necessary. The wires may
be soldered to the zinc and twisted in a hole
through the carbon plate. The whole may be
put together in a few minutes. Carbon (graphite)
is procurable free at the gas works. It is difficult
to cut, and it is generally cheaper to purchase it
ready qu,t. The zinc may be thin roofing metal, and
if used in acid solutions should be amalgamated
by rubbing with mercury after dipping in the solu-
tion. If attention is given to moving the pair in
the liquid occasionally, gilding may be done with
a plate of copper and one of amalgamated zinc
in a weak mixture of sulphuric acid and water

(Fig- i)-

I have gilded without the use of any special battery,
by employing the earth current generated by the
gas and water-pipes of a house. In damp places
this may often be done, simply calling the gas and
water-pipes the "poles" of the galvanic cell. It
will, of course, be necessary to find the direction in
which the current moves. It may very readily be
ascertained by plunging two plates of copper, con-
nected by wires with gas and water-pipes or fit-
tings, in a solution of copper sulphate; whichever
plate receives a deposit of copper—this will show
if the current is of use—is connected to the " zincAMATEURS' BATTERIES.	49

pole " of the cell, and the other connection may be
called the " copper pole."

Such weak generators may be used wherever
they are admissible, owing to the small current
required. The plates of a simple cell should have
a surface fully as large as that to be deposited
upon. Their shape is a matter of no conse-
quence. It is only necessary to mount them in
a bar of wood, by their upper ends, as near to each
other as practicable, without th^efea^g^jgsfj^eir
touching each other. The	b&Fcov^d

with cotton or gutta-percl
apart.

For Coppering and Ele\

nothing is better than ^vpair of Ddnielk^yj^of
simple construction.

and cheap outer pots. Within this pot goes one of
porous earthenware. (See Porous Cells.) The outer
pot contains a strong solution of the sulphate of
copper in water, and the porous pot very dilute
sulphuric acid (ten to one). In the outer pot goes
a roll of sheet copper, and in the porous cell a
slip or rod of amalgamated zinc. Solder the
wire to the zinc, or cast the zinc around it. Sol-
der also the copper wire, or at least twist it in
a clean hole through the sheet. This cell, so
charged, will work without alteration for nearly
a week. To join the cells, fix the zinc wire
of one to the copper of the other, and take
the remaining wires to the depositing vessel. If
one cell of double the size is wanted, join both

E5°

ELECTRO-PLATING.

coppers to one wire, and . both zincs to the
other.

When a powerful current of short duration is re-
quired, make a solution of bichromate of potash,
and strongly acidulate with sulphuric acid—three
ounces to the pint. In this plunge the zinc-carbon
cell. The current may be kept up for some time
by moving the plates up and down at intervals of
one minute each.

Workshop Batteries.

Doubtless the best galvanic generator for ordinary
use in the plating-room is a large Smee or Daniell.
The Smee is the most easily managed of any. (See
Frontispiece.)

Smee Cell. For Coppering, Silver ingy Electro-
typing, and all purposes requiring a good current of
large volume.—The containing trough should be of
oak, well jointed, and coated with lead or asphalt.
Its size will depend upon the work to be done.
For a vat to contain as much as 100 gallons of
solution to be worked with six anodes and deposit-
ing bars, the battery trough should be about three
feet long, by one foot deep, and the same wide.,
The solution is simply acidulated water, about one
to twenty, which may be renewed every week, or
oftener, if required. At such times it should be
drawn off with a piece of lead pipe, bent into the
form of a syphon. The electrical arrangement
consists of alternate plates of zinc and silver, orWORKSHOP BATTERIES.

51

zinc and carbon. Silver is the best, and may in
the end be as cheap as carbon. (See Carbon.) The
silver is platinised (see Platinum), and each plate
costs about 15s. They may be very th'in. Six
plates, that is, three zincs and three silvers, should
be used. To preserve the silver plates, their edges
and bottom should have a strip of lead doubled
over them and hammered flat; this lead should be

Eig. 7.—Daniell or Bunsen " Battery " Dissected.

well varnished. The zinc plates should be amalga-
mated. (See Amalgamation.) They may be mounted
in any convenient way: a series of cuts or slots
may be made in a wooden cover for the cell, and
the plates put down through them. The plate tops
should be fitted with projecting wood bars to pre-
vent their falling through. Very stout wire should
be used to connect the plates. All the silvers may
be connected together by soldered wires, but it is52	ELECTRO-PLATING.

much better to have upon each plate top a common
binding screw, so that the whole may be taken
apart when required: a wire may then connect the
binding posts. The zincs should be treated
similarly, when a wire from each combination will
form the two conductors—silver wire going to the
anode, and zinc conductor to the article being
plated. A stout cord should hook into the battery
cover, go over a pulley, and have a weight on its
other end, by which the plates may be conveniently
lifted out of the trough altogether when not in
action, and partly when a less current is required.
In this way the current may be regulated with the
greatest nicety (Fig. 9).

Copper and Zinc batteries have been used ex-
tensively, but they are wretched generators, and
wasteful in the extreme; this is the old Wollaston
form, and is now out of use. Platinised silver will
last for many years, and then may be sold for old
silver, so that the cost of a good Smee, although
more at first, comes to less than that of the
Wollaston in a short time.

Bunsen Cell.—This, next to the dynamo-electric
machine, is the best source of strong, steady
currents. It consists of an earthenware pot, hold-
ing about half a gallon (for large currents), inside
of which stands a pot, of the same height, and
narrow, of porous earthenware. These are the two
containing vessels: the outer one contains sulphuric
acid much diluted, and the inner one strong nitric
acid. The " metals " used are, for the outer pot, aWORKSHOP BATTERIES.	53

roll or cylinder of amalgamated zinc, and for the
inner one a block of gas-carbon. A wire from the
carbon and another from the zinc form the con-
ductors as usual. The battery is seldom used for
silver, gold, copper, or nickel deposition, and when
plating, such as brassing, is carried on which
necessitates the use of large or strong currents, the
dvnamo-electric machine ought to be used, as it is

Fig. 8.—Bunsen or Daniell Cell.	Fig. 9.—Smee Cell—Plates drawn up.

much less expensive, even with a special engine to
drive it. The action of Bunsen's cell goes on, when
strongly charged, with great vigour for four or five
hours, and weaker after. The nitric acid gives off
bad fumes, so that the cells should be placed out of
doors, or on a window-ledge. To join the wire to
carbon is no easy matter, as the carbon is porous,
and allows the acid to rise in it, to destroy any54

ELECTRO-PLATING.

connection made. A heading of lead may be
moulded upon it, and this may then be well soaked
in hot melted paraffin, the wire being soldered to
the lead. A brass clump, with contact parts plated
with platinum, makes a fairly good connection,
but the best possible heading is spoken of under
Carbons. These remarks apply to- all carbons,
although those used in Bunsen cells are more liable
than the others to bad contact. (See Figs. 7 and 8.)

Grove's Battery is sometimes employed in electro-
plating. Its construction is similar to the Bunsen,
the only difference being the substitution of pla-
tinum foil for carbon. The acids are the same, and
the time in action at full force about four hours.
To save expense the platinum foil is sometimes too
thin, and is very troublesome. The only real
advantage in the Grove cell is the flat shape of
porous cell often used. This renders the space
occupied very small; but the whole arrangement
cannot be recommended, and it is time that its use
was a thing of the past in practical electro-metal-
lurgy.

DanielVs Battery has been much used, but it
gives rather too much trouble for rough work, such
as brassing or even silvering. It is well fitted for
continuous gilding; for example, for the gilding of
wires, drawn regularly through the solution. It is
also very serviceable in shops where a great deal
of gilding is done, and for slow and fine electron-
typing. The containing-pots are the same as
those for Bunsen and Grove cells—an outer and aWORKSHOP BATTERIES.

55

porous cell. The liquids are solution of copper
sulphate in the outer cell, and acidulated water in
the porous pot. Copper goes into the outer pot, a
roll of" the sheet being used, and zinc, in the form
of a rod or cylinder, goes into the porous cell
(Fig. 8). It would appear to be necessary for me
to here warn the plater against a form of the cell
recommended in the text-books. It is simply the
old plan of making the copper cylinder into a com-
plete pot, and dispensing with the outer containing
cell. Such an arrangement is Very common, and
troublesome also, because the bottom joint usually
leaks after a little use ; and the first cost is greater
than that of the containing-pot. The construction
may be varied to almost any extent, as long as a
porous partition divides the two liquids. In action
the cell is very steady, furnishing a good current at
a constant strength for days together. If the acidu-
lated water is weak the cell may work regularly
for weeks together. Owing to this constancy, the
Daniell is well fitted for all purposes where a very
strong current is not needed. In practice the con-
taining cells should be earthenware jars holding
about a gallon ; the copper cylinders rolls of clean
sheet, with a binding screw soldered on to each;
the porous cells should be large, and the same
height as the outer pots ; the zincs should be thick
rods of the smoothly cast metal, and well amalga-
mated, and with a binding screw soldered to the
top. Four of such cells will be found strong enough
for almost all silvering operations employing56

ELECTRO-PLATING.

anodes twelve inches square. If the plater is ex-
perienced in his art, he will always use the Daniell
in gilding if there is much of it to produce.

Fuller's Battery.—This excellent generator of
electricity, lately introduced, is well fitted also for
gilding, and it gives even less trouble than the
Daniell, while its strength is greater. It is not,
however, suited to the plating of large surfaces.
The containing-pots are the same as before. The
zinc is in the form of a rod, flattened out at the
lower end, and coated with sealing-wax varnish
except at this end. A layer of mercury covers the
lower end at the porous cell bottom, and the cell is
then filled up with water only. The outer cell con-
tains only a carbon plate, with a solution of potash
bichromate strongly mixed with sulphuric acid—
one to eight. The circuit should be closed after
setting up for about six hours, when the action
will be much stronger than at first.

Amalgamation of Zinc Plates.—This simply means
the coating of zinc with mercury, to protect the
naked surface from what is called " local action."
This wasteful action is simply the result of hard or
soft, good or bad, spots in the zinc, and the waste
is caused by little local currents being set up
between them. A surface of mercury connects all
those objectionable spots together, and prevents
local currents from forming.

It is only necessary to dip the zinc in its solution
until its surface is clean, and then to rub the mer-
cury on from a soup-plate, with a pad of cottonWORKSHOP BATTERIES.	57

wool or rag. Rub until a perfect surface is obtained,
dip the plate in water, and set up to drain. There
is much more trouble with cast than with rolled
zinc, therefore care should be taken to cast rods in
a smooth casing, such as a roll of oiled copper
sheet, or an oiled taper brass tube. Sand should
never be used to produce good zinc. The neces-
sity for re-amalgamating is indicated when the sur-
face shows black patches which will not rub off.

Zinc for batteries should be of good quality.
Much of that sold is very impure. Rolled sheet
should always be used, because the surface is good,
and a tough zinc gives more force than cast plates ;
besides, it is almost impossible to properly amal-
gamate the latter. Its thickness should be nearly
I of an inch, and its price should not exceed four-
pence per pound. To bend into cylinders, it is
only necessary to warm or heat the sheet, when it
is easily curved. To easily cut, scratch deeply
with a steel point, run mercury therein, repeat on
the opposite side, and bend. Belgian zinc is
generally supposed to be the best for batteries. If
the new sheet is greasy, dip in caustic potash solu-
tion before proceeding to amalgamate.

Carbons for Batteries.—This substance is the
graphite of the gas retorts. It is not coke. It is
easily procurable in lump at any price, but costs
much more when cut into plates, as its working,
when the material is good, is exceedingly difficult.
It is generally cut with a thin strip of iron and
watered silver sand. Blocks for the Bunsen cost5§

ELECTRO-PLATING.

less because they are more easily produced. Blocks
may be had at tenpence per foot long, but plates
cost much more, dependent upon their breadth.
Rods for Bunsen cells should be a few inches
longer than the pots, to protect the top contact
from the acid. A good carbon is of a clear grey
appearance, has a finely granulated surface, and is
very hard. They will last any length of time.

Connection with the top for the wire is a more
difficult thing to obtain than would be imagined,
especially with Bunsen carbons. The best possible
plan is to electrotype a head of copper upon them
in a sulphate of copper bath. Proceed as follows:—
With a hot iron spread a quantity of solid paraffin
upon the rod from the point the liquid reaches to,
upwards to within half an inch of the top. See that
the paraffin penetrates the substance. Then cut
a few notches in the unparaffined head, drill a hole
right through, and fasten a wire to project a little
at each side. Tie a wire around the opposite end,
and immerse in the copper solution of the Daniell
cell, or treat the head in a proper vessel like any
ordinary work. When the copper is thick enough
to stand hard usage, remove the rod, and drill a
few holes right through the new head; soak in
water, and dry well in a hot place. Tin the copper
at the top, and if required solder on the wire or
binding screw, and then well soak the whole head
in melted paraffin. This will make an almost per-
fect and permanent connection, which the acid
cannot affect. Cells that are only to be used forWORKSHOP BATTERIES.

59

short periods need not be treated in this way,
because a fairly good connection may be made with
the ordinary brass clamp. But where Bunsen cells
are used for brassing, or such work, the carbons
should always be so headed. It is necessary to
keep Bunsen clamps very clean.

Binding Screws and Clamps.—These are turned
blocks of brass, with a hole run through to hold the
wire, and a screw to fasten it securely, and assist
in making a connection. Clamps are brass castings
fitted for clamping the heads of carbon rods, pairs
of Smee plates, zincs, and other purposes. They
are made in all shapes and §izes to suit the different
purposes. The price of binding screws ranges
from 3s. to 6s. per dozen. They also are to be
had in all required sizes, fitted with screws for
wood-work, or tails for soldering on to the plates.
The usual wood binding screw is a wretched affair,
the " screw " being merely metal-thread, and not
wood-worm thread. The French have introduced
a useful screw, having tails made from wood
screws. These should be asked for, as the others
are troublesome. They have also brought out
a good many new and useful patterns of large
screws and clamps. The contact holes of clamps
and screws must be kept clean. A rimer or a
small file will be found useful for this purpose.
Contact parts of clamps must also be kept bright,
as electricity will not pass through dirt. The
soldering on of screws may be done with a copper
bolt, resin, and soft solder; or spirit of salt,' saturated6o

ELECTRO-PLATING.

with zinc, may be used instead of resin, which is
very troublesome. Emery-cloth should always be
at hand and made use of every morning, not only
for battery screws which may be dirty at contact
parts, but for vat-rods, hooks, and the numerous
necessary connections about a large vat and
battery. Wherever soldering may be done, instead
of simply connecting, it is wisdom to employ it—
well-soldered connections never give any trouble.

Containing Cells for Batteries.—A battery " ele-
ment " or cell being composed of a pair or more of
zinc and copper, carbon or silver plates, immersed
in a liquid, a vessel of some kind is required to hold
both the " element" and the liquid—this is the
containing, or outer pot. Stoneware is the best
material in use. Pots of any required size are
obtainable. They should be in shape like common
jam-pots, and have no taper. Glass, ebonite, and
gutta-percha are entirely out of place in a plating
factory for containing-pots.

Porous Cells for Batteries.—These are procurable
in all required sizes. The price is something like
a penny per inch in height. Wedgwood & Co. make
the best pots. For the Bunsen cell the material
should be very porous, but not so much so as to
allow water to run off the sides when filled and
stood up for test. A dew should appear outside
in a few minutes if the pots are soft enough for the
Bunsen. Red material is better for soft pots than
white. For the Daniell cell the pots must be
harder, and of closer grain, and white earthenwareWORKSHOP BATTERIES.	6l

is the best suited. Porous cells after use should
never be set aside to dry, as they will crack. They
should be kept soaking in water until required.
The best cells are glazed at the top, but they may
be difficult of procural. Daniell cells are very apt
to deposit copper upon their porous partitions;
some of the nodules may be knocked off, and others
had better be covered with a chip of soft gutta-
percha. The tops of Daniell porous pots should be
soaked in melted sealing-wax, or in hot melted
paraffin, and it is wisdom to soak the bottom
also.

Unglazed pots are to be had either round or flat.
The round ones are, of course, the more useful.
Cells for Grove batteries are usually made narrow
and flat, to contain a little acid and a thin plate.
The form is a matter of little consequence. Sub-
stitutes for porous cells may be tubes , of brown
paper, stopped at the bottom, or wooden pots ; but
they are no economy, except as experimental ap-
paratus. Porous cells for all batteries except the
Daniell will last for many years if care is taken of
them. Porous earthenware partitions for trough
batteries are also procurable cheaply. They are
useful for making up Daniell cells in troughs
coated with marine glue.

Comparative Strengths of Batteries.—A great deal
of misconception exists amongst platers as tq the
value of the term electro-motive force. It is not my
duty to here explain its meaning, but a word or
two upon its significance in the workroom may be6 2

ELECTRO-PLATING.

acceptable. It means, then, power to overcome resist-
ance. Thus, we may have a current of vast volume,
but its force might be so low that a few inches of
liquid between the anode and article might by its
resistance entirely render the volume of no
practical use—that is, no metal would be deposited
unless we reduced the distance between, or rendered
the conduction of the solution better. Now a
current of very small volume, but of higher pushing
power or electro-motive force, might do a great deal
of work when one of low force would be useless.
It should be distinctly understood that the force,
pure and simple, is entirely independent of the size of
cell; a small cell has just as great power to carry
its modicum of current through a given resistance
as a cell infinitely larger. I wish it to be under-
stood that the word current is the expression used
to indicate the amount of electricity given off, with
no reference to its force or pushing power. Strong
current of course means a good volume of electricity
moving with much force—that is, electro-motive
force and volume combined.

Speaking as I do to the worker himself, who
cannot be expected to be a trained chemist or
electrician, and give, as he does, his services for a
small wage weekly, I am anxious to impress upon
his understanding the importance of these remarks
as bearing upon the practice laid down in this
work. He should understand that small volumes
of liquid may be worked with large currents if the
work is to be done quickly, but the currents mustWORKSHOP BATTERIES.

63

have force to overcome the resistance presented by
the small area of liquid. To understand that
liquids and solutions present an enormous resistance
to the passage of electricity when compared to
metals, will greatly aid the plater to an intelligent
conception of the laws of electricity and resistance,
as applicable to the purposes of electro-metallurgy.

Rules to work by are, of course, given here also,
but no specific directions can entirely grasp the
whole needs of a practical plater. The electro-
motive force, then, of the batteries spoken of is,
comparatively, as follows :—

Cell.	v	Comparative

force.

IOO

98

IOO

99

30

24

50

35

25

30

The statement of " force " must be accepted with
much caution. Thus :—It does not necessarily
follow that, although the force of a Daniell is
tabulated as half that of the Grove, it is equal to
half the work a Grove cell can do; two Daniells, or
even four, are not equal in working power to one
Grove cell, even although the surfaces are equal.
This discrepancy is due to the high conductivity of
the strong acids in the Grove, and to the low con-
ductivity, or enormous resistance, offered by the

Grove's, with purest nitric acid in porous pot
,, with nitric acid, specific gravity 1-33
Bunsen, with purest nitric acid .

with acid of specific gravity I *33
Smee, dilute sulphuric acid 1 to 12

„ 1 to 20 .

Daniell, with dilute acid 1 to 10
>» »> a 1 to 20
„ with half-saturated solution zinc sulphate
Fuller	,, ,, ,, ,,64	, ELECTRO-PLATING.

liquids of the Daniell. This resistance is called
the internal resistance of a cell, and it is only by
knowing the internal resistance that ihe resistance
it can overcome is known. A cell of high internal
resistance, such as the Daniell or the Fuller, is
always fitted for working small bulks of liquids, or
where the anodes and objects must be kept far
apart. They are only fitted for small, or slow
work, unless their plates are made very large,
which diminishes the internal resistance. It will
be seen that the Bunsen has the highest electro-
motive force, but it has higher internal resistance
than the Grove, and would not do the work so fast
as the latter, although it would do it, at a greater
distance from the anode, in less time than the Grove
current could. Hence it is that, because in gilding
the resistance is low, and owing to the small
current required and other conditions, the Daniell
and Fuller cells are suited to the purposes of the
electro-gilder. Further remarks follow, which may
be of use in the more clearly comprehending these
statements, but it must be upon clear general
directions only that the beginner can make a
commencement in the actual plating of metals by
electricity.

Management of Batteries.—To work the large and
generally applicable Smee cell, observe that the
zinc plates are properly amalgamated at the com-
mencement of operations. The usual amount of
sulphuric acid mixed with the water is one part to
fifty. If a weaker current will serve, employ halfMANAGEMENT OF BATTERIES.	65

that amount. If a stronger current is required,
make the mixture a little stronger. The3e large
cells only require " refreshing" about every five
days. The acid should be mixed with water, and
stirred in. As soon as the liquid begins to feel or
look oily, through a strong admixture of zinc sul-
phate, draw it off, and make up a fresh mixture.

The plates must be watched from time to time,
and if the amalgamation shows black patches, it
must be repeated. The stronger the mixture the
more need is there for frequent watching. As soon
as the bath is done working, always lift the plates
clear of the liquid to save the zinc. MftisLcom-
municating any mercury to thg^^^^Yat^^^t

apt

To work the Bunsen sudcessfuHy\at full power, dJf
constant watch should bet^ept upon the amalga-
mation. In working with fuft^rrqi^\^eTC|^charge
the battery until the work is rraSyTo be done.
Happily, so powerful a current is not required in
silvering, gilding, or nickeling, so that a Bunsen
cell with the strongest charge is not often needed.
The nitric acid should be used over and over again.
Work the acid until it turns red, then green, and
until it becomes colourless again,, by which time it
is useless. Bunsen cells with a good current can
be kept in action about ten hours. When the nitric
acid is by accident spilt upon the zincs, it sets up
local action and great waste. If the nitric acid is
weak, and the acid mixture in the outer cell about

F

spoils them for good work^?^mNmey. are apt to
break.	ff	J66

ELECTRO-PLATING.

one to fifty instead of one to ten, the action may
be prolonged for many days at a time. In this
condition the cell may be used for silvering, or other
work usually done by the large plating-room Smee.
The Bunsen has also been used for gilding, but it
is a wretched waste of zinc to work in this way.
In using the Bunsen with concentrated nitric acid,
fumes are given off, which are very strong as the
pots are being emptied: they must be avoided, as
they are exceedingly unwholesome, nor should they
be allowed to spread in a room wThere they can do
harm. It will be useful to have two sets of porous
cells for the Bunsen, so that one set can be soaking
out the nitric acid in water, wThile the fresh ones
are in use. All the brass parts, plates, and any
connections of the Bunsen battery should be washed
in water after pulling to pieces, and emery-cloth
must be made good use of for the contact points.

To work the Daniell Battery.—This cell gives
very little trouble when properly attended to. The
amount of management required will depend in
great degree upon the charge in the zinc compart-
ment. If the cell is worked by strongly acidulated
water, the attention required will be at a maximum,
and in this " short period " condition, the battery
cannot be expected to work without attention over
seven days. If, on the other hand, gilding only
has to be done, or a weak current only is required,
we charge the zinc pot with water only. The result
is that, after a few hours' work, zinc sulphate will
be formed, which will serve in the water to workMANAGEMENT OF BATTERIES.	67

the cell without any attention for months at a
time; in this state the attention required is at a
minimum. So little attention as this will not serve
the Smee battery, no matter how weak the acidu-
lated water may be made. Hence the advantages
of the Daniell in electro-gilding, or when a small
current is required.

No sooner is the circuit of the Daniell closed,
than the copper solution is decomposed into its
constituent parts—copper and sulphuric acid. The
metal is deposited upon the copper cylinder, and
the sulphuric acid finds itself drawn into the porous
cell, where it maintains the zinc solution in a con-
stant condition. The whole cell is, in fact, nothing
less than a depositing vessel, ^and it may be worthy
of remark that the Daniell cell afforded the first
opportunity for observing electro-deposition ; it was
the ab initio of electro-metallurgy and all it has
grown into. The copper is thus by deposition
kept perfectly clean, and from accumulating a film
of gas, which in many cells puts a stop to the
action, and the zinc cell is constantly supplied
with sulphuric acid. The chief trouble is the
liability of the copper to find its way into the
porous pot by that troublesome creeping action
called endosmos. If copper is allowed to get into
the porous pot, it will be deposited upon the zinc,
act with that metal as a small local cell, and waste
the zinc without adding to the outside circuit cur-
rent. The tops of porous pots should for this rea-
son be well steeped in hot melted paraffin, and as68

ELECTRO-PLATING.

the bottom is also very apt to accumulate nodules
of copper outside, it should be treated in the same
way. The copper solution should be strong, and
as soon as the liquid shows a pale colour, instead
of a deep blue, more copper sulphate should be
added. A great many methods exist by which the
copper solution is kept up, by crystals hung in it
and otherwise suspended. I simply consider this
an excuse for laziness, and it will result in the cell
being forgotten at times when it ought to have
attention. It works well enough for telegraph
batteries, but it is a much better plan for the plater
to throw in some crushed copper sulphate—a small
quantity—every few days, according to the work
doing. If the sulphate is crushed finely enough it
will melt before it reaches the bottom, and give no
trouble. As to the zinc cell, if it is worked by zinc
sulphate, as before suggested, no amalgamation of
the rod is required; but if the usual acidulated water
is employed, the amalgamation must be attended
to about every month or less. The solution, in the
first case, should be one half saturated with the
zinc salt, and when the mixture is seen to deposit
crystals about the zinc, half of it should be poured
out, and water added. A watch should be kept
upon the porous pot for nodules of copper. If they
can be knocked off, do so, and cover the spots, if
not quite free of copper, with soft gutta-percha or
marine glue, or even shellac varnish. Npdules will
grow with astonishing rapidity if they are not
covered or removed regularly. It is wise to haveREMARKS UPON BATTERIES.	69

two sets of porous pots for the Daniell—one set
being left soaking out its salt while the other is
working. Connections may be wires simply sol-
dered on, but it is much better to have binding
screws' upon the metals.

To work the Grove cell, the directions given for
the Bunsen will answer perfectly.

To work the Fuller cell, attend to the bichromate
salt solution. When it shows pale, add more salt,
and some sulphuric acid ; also give attention to the
zinc sulphate solution, and treat otherwise as a
Daniell—there will be no trouble with deposited
copper, and the salt does not creep much.

Remarks upon Batteries.

For all real large work in the direction of copper-
ing, electrotyping, silvering, and nickeling, it is
wisdom to use the large Smee only. This is a good
advice, the result of long experience. (See Dynamo-
Electric Machines.)

For gilding, or work requiring only a small
current, use may be made of the Daniell in prefer-
ence to the Smee or Fuller; but the Smee will do
the work well, and the Fuller will do for small
work.

For brassing, depositing iron, and all work re-
quiring a powerful current, make use of the Bunsen.
(See also Dynamo-Electric Machines.)

Except for coppering alone, it is wise to have
the Smee trough divided, by wood welj. pitched, in70	ELECTRO-PLATING.

the middle, so that two Smee cells may be at hand
when required. Have, say, two silvers and two
zincs in each cell, and when higher electro-motive
force is required, join the silvers of one cell to the
zincs of the next, and wires from the remaining
zincs and silvers will give the force of two cells and
the current of one only. In ordinary work, when
high force is not required, and great volume is of
more use, join all the zincs to one wire, and all the
silvers to the other. These junction wires should
be of copper, and stout, and should be insulated,
covered with gutta-percha or tarred hemp.

Cost of Batteries.—A large pair of Smee cells, with
plates a foot square, four plates in each compart-
ment, and well made, can be purchased, or made
to order, for less than	Or the same may be

made in the plating-room, using large jars instead
of a trough, not reckoning labour, for £$. Such
batteries last for many years, but of course care
must be taken to renew the zinc plates when worn.

The DanielL—A pair of these cells, holding
when empty about a gallon of liquid in the outer
pot, should not cost more than^i ios., and they
may be made for half that sum, not reckoning
labour. A pair will usually be enough.

The Bunsen.—Six of these should be at hand.
A battery of this number of half-gallon Bunsens
should not cost over £2 ios. It is not better to
make than to buy these, because ziuc and carbon
are so hard to work without the proper tools.

The Fuller.—This being at present (1879) quite aREMARKS UPON BATTERIES.	71

new cell, it will be better to make than to pay-
fancy prices for it. A pair, of half-gallon size, will
usually be enough. For very large cells, it will be
best to mount three blocks of carbon around a
circular cover of lead, instead of one plate only.

Regulating the Force and Current of Electricity.—
The limits within which good work may be pro-
duced in silvering, coppering, and gilding are for-
tunately pretty far apart, but a great many of the
solutions require careful regulation of the current
to get a good deposit. Throughout my remarks
upon solutions are scattered directions as to the
use of the power with which we are dealing, but
they simply point to the fact that higher force is
needed here, less force there, more volume, and
so on.

To gain electro-motive force, or a stronger current,
immerse the plates so that the surface of each plate
will correspond to that of the anode, and add more
cells, by joining their zincs to the already used
carbons or silvers as the case may be—this is
called adding in series, and each cell so added
augments the force or power to drive a deposit over
a surface, or to work through high resistance.

To gain greater, larger, or more voluminous cur-
rent, use more surface in the battery. That is, im-
merse the Smee plates farther, or if the battery is a
Daniell or Bunsen, join other cells, copper to
copper and zinc to zinc; or, which comes to the
same thing, join, all the coppers to one wire, and
all the zincs to the other. It is very seldom indeed72

ELECTRO-PLATING.

that the plater need be at fault. (See also Dynamo-
Electric Machines.)

If the force from one cell is too high> which is a
rare occurrence, interpose a few yards of fine
copper or iron wire in the circuit.

The ordinary terms "intensity " and " quantity "
of current have not been employed in this treatise,
simply because the term intensity is not rightly
applied, and leads to erroneous notions of electric
force, and both terms would be somewhat puzzling
to the every-day worker. I have discarded them,
and expressed myself in the words " force,"
"strength/' "current," "volume of current;" in
short, those expressions which, although not used
much in the text-books, convey the fact to an
average mind intelligibly.

The Galvanometer.

Some platers, especially those with little or no
scientific knowledge, who work by " rule of thumb,"
get through the best of work without any instru-
ment for detecting the presence of electricity, or
measuring its strength. It is not unusual in the
plating-room to test the strength of the current by
placing the wire ends on the tongue; others test
by the spark which will pass between the ends on
separating them, and by running one end upon a
file to which the other is tied. These latter methods
are of the most delusive kind possible, and will
only be a rough guide with one particular length ofTHE GALVANOMETER.

73

wire, for long wires give much longer and larger
sparks than short ones.

It is far better to possess even a five-shilling gal-
vanometer. The construction is easy enough, as a
galvanometer for detecting currents, and to a cer-
tain extent indicating their strength, is only a
suspended magnetized needle, having around it a<
few turns of insulated wire. The law is, of course,
that a freely suspended magnetic needle will tend
to place itself at right angles to a wire through
which a current is passing.

Galvanometers should have two circuits—-one of
fine wire and a good number of turns for weak
currents, and another of a few turns of stout wire,
or one turn only, for very strong currents. With
all such common galvanometers comparisons only
can be made, and not absolute measurements of
electricity. They are very useful for various pur-
poses in the plating-room, especially in testing the
strength of new cells; or, being placed in the
circuit, indicating whether or not the battery gains
or loses power during any plating or typing opera-
tion. The stout circuit is usually suitable as an
indicator of the state of the current before com-
mencing work every morning, or after cleaning out
and refreshing the battery. Tests taken during
the working and at other times will show when the
solution of zinc sulphate is getting so strong as to
weaken the current, and when it is time to renew
the acidulated water. Good galvanometers, with
two circuits and needle on agate centre over74

electro-plating.

graduated card, can be procured at prices varying
from i os. to £2. Sprague, electrician, Green
Lane, Birmingham, patented, in 1876, a measuring
galvanometer of very great value to the educated
electro-plater.

Dynamo-Electric Machines.

Within the last ten years the dynamo-electric
machine has to a very great extent superseded
the battery in factories, especially where strong
currents are required. Electricity is cheaper by
magneto-electric machine than by battery. It
will be unnecessary to tell the reader what a
dynamo-electric machine is. Every one knows the
medical " shocking" machine of Clark's design:
a dynamo-electric machine is upon the same
principle, but vastly improved. It is driven by
steam or other continuous power at high speeds,
and the currents generated by the revolution of
coils of wire having iron cores in front of electro-
magnets, are usually passed into the electro-
magnets to further strengthen them. The aug-
mentation of force reacts by magnetic strain upon
the revolving coils, and thus a current is raised
trom only a little magnetism by the parts reacting
upon each other as the coils revolve.

Suppose a simple Clark's " shocking" machine
to be fitted with a wire-coiled soft iron electro-
magnet, instead of a steel permanent one, and
suppose that the currents generated by revolvingDYNAMO-ELECTRIC MACHINES.

75

the usual pair of coils in front of its poles are sent
through its wires instead of direct to the hands, it
will be clear that if there is but a trace of magnet-
ism ("residuary magnetism") in the soft iron,
motion of the coils must augment it by sending
through weak currents. The electro-magnet repays
by exerting increased magnetic force upon the

Fig. 10.—Weston Dynamo-Electric Machine.

coils, which in turn give increased currents to the
magnet, and thus the action goes on until the
magnet is magnetized to saturation, when the cur-
rent will have attained its maximum strength.

The same thing takes place in almost all the
dynamo-electric machines lately brought into use—
electro-magnets react upon electro-magnets until
the resistance is very great, and needs consider-
able power to overcome it. The currents given off76

ELECTRO-PLATING.

will depend for their electro-motive force upon the
number of turns the insulated wire takes around
the electro-magnets, and for its working power, or
volume, upon the size of the wire used. Thus
machines can easily be produced which will supply-
electricity of any required volume or tension, and
some machines are supplied with two revolving
armatures or coils, interchangeable to obtain cur-
rent of high or low tension. The speed required
to produce maximum effects will depend upon the
softness or bulk of the armatures and magnets.

Names of Machines.—The machine first in use in
England for the purposes of copper deposition was,
I believe, the old form of Holmes, which is now
very much improved. Wild's machine was also
used, and after this the machine of Gramme be-
came known. Also Siemens', and several very
good American machines, the best of which are
the Weston and Wallace Farmer.

A technical description of the machines would
not only be out of place here, but would involve
the occupation of a great number of pages. The
plater need not concern himself as to the exact
construction, so long as he understands the work-
ing of the machine, and how to adjust its current
to the work doing. In vols. 5 and 6 of Design and
Work will be found my own technical and illus-
trated descriptions of the various machines in use,
and to these, and English Mechanic, I must refer the
reader for special information concerning them.

Dynamo-electric machines are especially suitableDYNAMO-ELECTRIC MACHINES.	77

for the deposition of nickel, silver, and copper, and
in continuous brassing they are almost indispen-
sable. Gramme, Weston, Siemens, and the other
firms produce several sizes suited to the different
purposes. Thus a small machine, requiring about
two horse-power to drive it, will usually be enough
for silver, nickel, and gold, and also for fairly large
operations in copper deposition. Dynamo-electric
machines are spoken of as being capable of deposit-
ing so much silver per hour per horse-power used;
this is a fairly reliable guide to platers, who know
quite well how expensive a battery to do like work
must be. A good dynamo-electric machine should
be capable of depositing something about 30 ounces of
silver per hour for each horse-power used. I must,
however, warn the plater not to accept at once the
figures of makers as to power necessary, for it is
conspicuous that machines usually require much
more power than that stated to be sufficient.

Gramme's large machine, for depositing large
bulks of copper, is run at about 300 revolutions, the
small ones at 600, and- others as high as 800 per
minute. The speed necessary is always high.

The machines should be mounted upon a stand,
fixed steadily, and in a dry place. It is necessary
to frequently adjust the commutator, which carries
the current from the revolving axis. When the
current is too strong, interpose a length of fine wire
(preferably iron) in the circuit.

The Weston Dynamo-Electric Machine.—Other
writers have spoken of the Holmes, Wil$, and78

Electro-plating.

Gramme machines, and in their works will be
found some particulars of their application to
electro-metallurgic purposes. I shall give such
particulars as I may deem useful concerning a
beautiful development of magneto-electric prin-
ciples—the new Weston machine. Of its working
I have had personal experience, and for the
purposes of electro-plating and typing, feel in-
clined to recommend its use in preference to the
types above mentioned (Fig. i o).

The engraving, Fig. n, represents this machine
with the driving band and copper conducting-straps,
a a, leading the current to the plating or typing vat.
The interior consists of six electro-magnets, fixed
rigidly to the iron drum, within which, and closely
approaching their poles, revolve other six magnets,
wojind with finer' wire, and fixed, of course, to the
revolving axis. The mechanical details are very
compactly arranged, and the electrical parts are
laid out with considerable skill. Upon the end of
the shaft is fixed the commutating arrangement,
f, consisting of brass contact-pieces, separated by
wood. 11 are a pair of bushes or pads made of
thin brass or copper slips, which take up the im-
pulses from the contact-pieces. Six alternate
currents are given off at each revolution, and
they are converted into three direct impulses by
the commutator. These impulses are, of course,
sent by a a to the deposition vat.

The driving-band, j, works an ingenious contri-
vance for preventing the magnetic polarity of theDYNAMO-ELECTRIC MACHINES.	79

machine from being reversed. It will be well to
explain what this means, as it is due to the plating-
vat, and not to any fault in the machine. When
electro-deposition is being effected, there is a
tendency to store up in the vat, at the plates, an
electric force opposed to the real current, and when
the machine is stopped this reverse current must at
once make its way through the circuit. The result

Fig. 11.—Weston Dynamo-Electric Machine.

is that it first destroys, and then reverses the
polarity of a common machine, like that of Gramme.
What takes place when the machine is next started
will be obvious enough—the currents will flow in
the reverse direction to that required, and metal
will be dissolved off the goods and go upon the
anode instead of the reverse. The arrangement B
is intended to prevent anything of this kind happen-8o

ELECTRO-PLATING.

ing, by cutting the circuit open as soon as the
machine is stopped.

Attention should be given to the commutator at
least daily. The pads of copper slips should be
easily adjusted, but they must not press very heavily
upon the commutator; if they do the ends will pro-
bably seize the commutator, and begin to cut it up.
This part should not be oiled, and the same may be
said of the commutator of every machine.

Care must be taken that the oil-cups do not get
empty, because the speed is very high.

The whole front end of the machine is movable
around the axis, and with it the commutator pads.
The object is to render the machine capable of
being controlled as to its volume or quantity of
current, by altering the period of closure of circuit
by the pads—thus the impulses may be made long
or short at will. Resistance-coils for moderating
the currents are supplied.

Gramme's, Weston's, and Siemens' machines are
made in three or four different sizes. Weston's
smallest machine may be driven by hand, but hand
machines are of little use except for short operations
and laboratory practice. A hand machine, giving
a current equal to that from five Bunsen cells, is
procurable of M. Breguet, Boulevard Mont Par-
nasse, Paris, but the price is very high. As to
prices the usual rate for a small Gramme, Weston,
or Siemens is about ^50, without counter-shaft.
Some machines require less power than others for
equal currents. Siemens' type is probably the bestDYNAMO-ELECTRIC MACHINES.

8l

converter yet devised. The second size Gramme
(Fig. 12) will deposit something like twenty ounces
of silver per hour for

tabulated at ten ounces

ral Platers Outfit Fig. 12.—Gramme's Electro-plating

Dealer, 41, Queen Vic-	Machine.

, toria Street, E.C.; Siemens Brothers, Electricians,
London, for Siemens.

Several of the chief printers now use the dynamo-
electric machines for their typing work instead of
batteries—W. & R. Chambers, of Edinburgh;
McCorquodale & Co., London—and their use in
the deposition of all the metals, especially nickel,
is extending rapidly. The engraving of Gramme's
machine represents the largest type, with vertical
magnets.

GCHAPTER IV.

Deposition of Copper.

Its Salts.—The most common salts of copper are
the sulphate, acetate, nitrate, cyanide, chloride,
protoxide, and suboxide.

Sulphate of Copper.—It is always better to pur-
chase this than to attempt its production at home
or in the plating factory. It may be obtained
nearly pure at about 6d. per pound. A good test of
its quality is in its appearance. The crystals
should be as large as hazel-nuts, and of a clear
deep blue colour. The poorer qualities always con-
tain an admixture of green substances. These are
iron, and samples showing it should be discarded.
This salt is also commonly called " blue vitriol,"
" blue-stone," and " Roman vitriol."

Acetate of Copper.—This is very generally called
" crystallized verdigris." The crystals are dark
green. It is distinguished from common verdigris
by its finer quality. Acetate of copper is more
cheaply obtained by purchase than by making at
home. It is somewhat expensive, as its price
varies from 4s. to 6s. per pound, but a smallSALTS OF COPPER.

83

quantity is usually sufficient for the purposes of the
electro-plater.

Nitrate of Copper.—It is usually made by dis-
solving clean copper sheet in nitric acid, afterwards
evaporating the solution nearly to dryness by boil-
ing and setting aside to crystallize. It may be
obtained commercially, pure, at about 2s. per
pound.

Cyanide of Copper.—This salt is much used. It
should be made at home. To make it, prepare a
solution of cyanide of potassium, four ounces;
water, one quart. Prepare also a solution of like
bulk, using, instead of cyanide, sulphate of cop-
per. Pour the cyanide solution into the copper
one, slowly and with stirring, just as long as a
precipitate is thrown down. Pour off the liquid
portion, and wash the powder, which is copper
cyanide, by filtering with more water. The powder
should be of a good green colour. Care is necessary
to avoid the fumes of cyanogen given off during the
precipitation, especially if the potassium cyanide is
of fine quality.

Chloride of Copper.—" Aqua-regia"—one measure
of nitric acid and two of hydrochloric acid—is em-
ployed to dissolve the copper, the solution being
afterwards evaporated nearly to dryness and set
aside to cool and crystallize. Commercial price,
5s. per pound.

Protoxide of Copper {Black).—The nitrate is
usually employed to form this. It may readily be
converted into the black oxide by heating to red-84

ELECTRO-PLATING.

ness in a covered crucible. The mass is set aside
to cool, when it is washed and dried. Commercial
price, 3s. per pound.

Suboxide of Copper (Red).—It is always better to
purchase than to make this salt, as it is seldom
used. Its price varies with that of copper, but it
may be taken at about 6d. per ounce.

Simple Immersion Coppering.—This process is
applicable to the coating of articles of iron or steel,
so as to give them the appearance of being made
of copper, or to protect them from rust. A solution
of copper sulphate is made (saturated), and to this
is added one-half its bulk of acidulated water. The
articles must be cleaned Well, and immersed for a
minute until a coating is obtained, when they are
taken out and well washed, and afterwards quickly
dried by plunging in boiling water and steaming
off, or placing in hot sawdust. If the articles do
not get well coated in this solution, dilute it still
further, and try again.	^

I have seen the coating of small iron articles
carried on by shaking them about in sawdust
well wetted with acidulated sulphate of copper
solution. Another process, suited to the coating ol
cast-iron articles, is carried on with a solution
composed of ten parts of nitric acid, ten of chloride
of copper, and eighty of hydrochloric acid. The
articles are immersed several times, and rubbed
with a woollen cloth between each immersion. In
the coating of iron wire, it is recommended
that drawing the wire be resorted to so as to con-DEPOSITION OF COPPER.

85

solidate the coating and give it better adhe-
sion.

The simple-immersion process employed for the
coating of such large objects as statues and lamp-
posts is carried on in a solution composed of water,
five gallons; fifteen pounds of sodio-potassic tar-
trate ; five of soda lime, and two of copper sulphate.
These substances are im,mersed in the water and
well stirred, and if there is any difficulty in dissolv-
ing them the water should be warmed or plenty of
time given. The articles should be immersed in
the liquid by means of zinc wires, or a piece of zinc
should be tied to and immersed with them. The
work is done slowly, and at least five hours are
required to effect a good coating of the metal. The
articles must be well washed in water after coating,
and dried.

Coppering by the Battery Process.—This is by far
the best method for copper-plating, as any required
thickness of copper can be laid upon the article
quickly. The connection between the real and
false surfaces is of a much more permanent and
satisfactory character.

A good coppering solution may be made by dis-
solving four pounds of crushed copper sulphate in
twenty pounds of water, adding, after the sulphate
has dissolved, one pound of sulphuric acid of good
quality. This solution should be filtered and kept
clean. It will not do for depositing upon zinc,
steel, or iron.

For deposition upon steel, iron, and zinc, a86

ELECTRO-PLATING.

cyanide of copper solution is required; throw
down the cyanide with a solution of potassium
cyanide, wash, collect, and dissolve in a solution
of cyanide of potassium. A simple way to make
the solution is to dissolve two pounds of cyanide
of potassium (50 per cent.) in a gallon of ^yater,
add cyanide of copper as much as the liquid will
dissolve, and then add free cyanide of potassium,
of which about four ounces will suffice. When in
use this solution should be heated, although it will
work cold, but in the latter case the deposits will
not be so smooth, or adhere so well, and more
battery current will be required.

The first solution will be found suitable for all
; purposes of copper deposition upon moulds for
electrotypingy or upon ordinary articles for plating
them with copper. Articles to be coppered are
cleaned in the usual way (see Preparation:), and
hung in the solution a few inches from the anode
by means of a copper or brass wire. If the deposi-
tion goes on too fast, the coating will be of a dark
colour, and the metal will not stand. This is
generally caused by too strong a current, and may
be remedied without altering the current by with-
drawing the object from the anode, so as to inter-
pose greater resistance to the current. If the work
is done too slowly, the deposit will be of an exceed-
ingly fine and crystalline nature, and very liable to
crack. This is caused by too weak a current, or by
tfie anode and article being too far apart. The
remedy in either case is obvious.WORKING COPPER SOLUTIONS.	87

Anodes for Copper-plating.—These are simply
sheets of clean copper. They are connected to the
copper pole of the battery, and are hung in the
solution so as to enable the plater to expose more
or less anode surface to the solution at will. If a
galvanic cell is joined to a pair of copper sheets,
one on each side of a vessel containing sulphate of
copper solution, one of the sheets will begin slowly
to dissolve, and the other to acquire a deposit of
copper upon its surface. This will go on until all the
copper of the anode will be thrown upon the re-
ceiving plate, while the solution remains sub-
stantially the same—that is, its original copper is
upon the plate, but a fresh supply has been ob-
tained from the anode. This is the fundamental
peculiarity of the plating process.

Working Copper Solutions.—The battery power
should be two cells for general work, and where
the resistance is very low, one cell may be em-
ployed, but greater satisfaction will be secured
with two. Their plates should have an area at least
equal to that of the anode or anodes employed.
They must be of the constant kind, and Daniell's
or Smee's will be found the most satisfactory cells
in work. It is a good plan, where Daniell cells
are employed, the plates of which acquire great
deposits of copper, to use such plates for anodes,
so that some immediate return for the expended
copper may be secured. As in all other plating
operations, a bar should be laid across the edges
of the vessel containing the solution; this bar88

ELECTRO-PLATING.

should be connected to the zinc pole of the battery,
and the articles to be deposited upon hung upon it
into the solution. It is usual and handy to provide
another bar, carrying the .copper anode connected
to the copper pole of the battery. This bar may
be in two halves, held together by strong india-
rubber bands, so that the anodes may be clipped
by it and pushed into, or withdrawn from, the solu-
tion at will without any other arrangement. In
this way one anode plate will usually be sufficient.
But many other arrangements may be adopted
suitable to special kinds of work, most of which
are touched upon in my remarks upon Vats (p. 17).

Copper is very easily deposited, and it is upon
this metal that I should recommend the would-be
plater to serve his apprenticeship. It is cheap,
and little loss can occur in its use. These remarks
apply only, however, to the copper sulphate solu-
tion, cyanide solutions being more difficult of
management. Care must be taken that the solution
does not become too dense. This defect will be
indicated by streaks upon the articles, and a
thicker deposit upon the lower than upon the upper
parts. Water should, in such cases, be added, and
the solution stirred. It is wise to stir up the liquid
every evening after stopping work. A little diluted
sulphuric acid should be stirred in every evening
if the anode does not look bright and clean. But
care is necessary that too much free acid is not
added, because in some cases the anode will be dis-
solved while the current is not passing; and whenDEPOSITION OF COPPER.

89

the current is passing, the anode will be caused to
dissolve faster than is required to supply the metal
being deposited upon the article. This would
cause the solution to become very dense, and to
deposit unevenly, and in streaks. Impure anodes
are exceedingly troublesome, as they become black
with a kind of dirt which is usually insoluble in
the solution. The remedy is to employ either the
copper cylinders of the Daniell battery, or to em-
ploy a more expensive kind of copper sheet. With
care, by brushing and other treatment, the anodes
may be kept clean, but this rubbish, which consists
really of a wonderful variety of common and rare
metals, chiefly tin, collects at the bottom of the
vessel, and must not be disturbed, as it settles upon
the'articles being plated, causing dirty work.

In working the solution of cyanide of copper in
cyanide of potassium, great care is necessary to
look after the amount of free cyanide. If there is
too much free cyanide, the anode will dissolve too
fast, and a great deal of dirt will fall to the bottom.
If there is too little, the anode fails to dissolve, and
the conductivity of the solution is impaired, so that
the current cannot do work, and is wasted upon
resistance. To obtain thick deposits from cyanide
solutions, greater care is necessary than in working
sulphate ones. There is a greater tendency to stop
depositing, owing to a dirty surface and other con-
ditions. The surface obtained from sulphate solu-
tions is exceedingly beautiful, but those deposited
by the cyanide liquids are usually very bad in9°

ELECTRO-PLATING.

colour, and need extra scratch-brushing to bring
them up. When very thick deposits are required
upon iron or zinc, it will be found almost necessary
to first secure a very thin coat in a cyanide solution,
remove and wash rapidly, dipping at once in the
sulphate solution, from which any required thick-
ness may be secured.

Distance between Anodes and Articles.—This varies
greatly with the size of the objects, their shape,
and the current passing. Small surfaces or electro-
types upon which a rapid good deposit is required,
may be kept as near as possible to the anode—that
is, about one or two inches from it—if the surface
is flat, but if there are protruding parts and inden-
tations, the distance must be greater on account of
the tendency of the deposit to go on fastest upon
the nearest points. Much more equal deposits are
to be obtained when the distance is six inches than
could be secured at three inches, unless the surface
is really flat and parallel to the anode plate. To
a great extent the rapidity of deposition is depend-
ent upon the nature of the surface, and upon the
distance apart, because both these conditions affect
the strength of the current passing. The nearer
the article is to the anode the faster will the work
go on. But attention must be paid to the condi-
tion of the metal. If the work is done too quickly,
or with too strong a current, the metal cannot be
depended upon, and if it is done too slowly, or
with too little current, the metal will be crystal-
line. From the cyanide solution the deposit ob-ELECTROTYPES.	91

tained with ordinary battery power is of a dull
colour; but when the current is added to, the coat-
ing is nearly bright.

Time necessary in depositing Copper.—In sulphate
solutions there should be no difficulty, with a suit-
able current and the object and anode properly
arranged, in laying a thickness of one-eighth of an
inch in two days, and when the work is forced, with
the utmost applicable current, a good electrotype
should be obtained in ten or twelve hours—and
this of good tough copper. Copper-plating should
be done to a good thickness in one hour or less.

Electrotypes of Copper.—In the foregoing remarks
are given the necessary directions for depositing
the copper upon goods direct, securing a plating of
copper. Electrotypes, on the other hand, axe copies
of objects in copper, and have, therefore, a separate
existence of their own. They are removable de-
posits. If an ordinary coin is deposited upon as
in simple plating, but with the precaution not to
chemically clean it so that the deposit may not
permanently adhere, the plating will go all over
it. If a thickness of writing-paper is allowed to go
on, it may be cut off, upon removal from the solu-
tion, with a knife. It will be observed that, as the
deposit is easily removable, it has upon its inner
face the finest possible lines and markings of the
original. It is, in fact, a complete facsimile, in
reverse, of the coin's surface. The copper deposited
upon the Daniell cell cylinders will be found upon
removal to have taken an exceedingly faithful92

ELECTRO-PLATING.

copy of the surface upon which it has been
thrown.

In this work no notice has been taken of the
historical facts relating to the discovery of this
curious property of electro-deposition. They are
to be found in pages devoted to complete theo-v
retical and historical dissertations upon this art,
and therefore do not concern us in a purely prac-
tical book like this. It was soon found that the
remarkable property spoken of could be turned to
good account for every-day purposes. Copies of
solid objects could be obtained; rare coins could
be copied without the possibility of error; objects
could, in fact, be multiplied to any extent without
injury to the original. Woodcuts may be repro-
duced with the greatest accuracy in any quantity.
Set-up type may be copied, and the copy printed
from. Birds, fishes, leaves, insects, busts, and all
imaginable kinds of solid objects are copied with the
greatest fidelity. The art is known as electrotyping.

To obtain a copy of one face of a coin or medal-
lion, it is only necessary to apply to its centre a
ball of softened gutta-percha; this is passed out-
wards, so as to exclude all air, until the surface is
covered, when the two are firmly pressed together
in a vice, or beneath a weight. As the gutta-
percha cools, a greater pressure should be applied,
and when the moulding material is quite firm, the
two may be separated. This faithful mould must
now have fixed in it the end of a heated wire, near
to the face edge : this will form the necessary con-ELECTROTYPES.

93

ductor. Blacklead is now brushed on until the
surface is uniformly coated, and appears brightly
polished, the wire and adjacent parts receiving a
good share of attention. This mould may now be
deposited upon in the usual wTay. The deposit will
begin to form upon the wire, and will gradually
creep all over the surface. The back being plain
gutta-percha, no deposit can form upon it. When
the deposition has attained a reasonable thickness,
or that of brown paper, it may be removed from
the mould, and its face will present a faithful copy
of the original coin. It will be found more difficult
to deposit upon gutta-percha articles coated with
blacklead than upon plain metal direct. In such
cases a greater tension of current will be necessary,
and as many as three cells will be found to supply
the required force.

These short directions cbntain the fundamental
principle adopted in the production of the greater
number of electrotypes. Different substances are
used upon which to take an impression of the
object. Wax is very frequently made use of, fusible
alloy, an elastic glue and treacle compound, and
plaster of Paris.

Gutta-percha for Moulding.—Perhaps this is the
most generally useful material. The greatest care
must be taken in copying woodcuts to make sure
that the substance is perfectly free from grit or
foreign .substances of a hard nature, as the pressure
is apt to destroy the cut. Gutta-percha cannot be
used to surround any object, because it shrinks on94

ELECTRO-PLATING.

cooling. It is well adapted for flat surfaces. The
softening should be done in boiling water, and the
gutta-percha worked into a ball, which is then
applied soft to the middle of the article and worked
carefully out to the edges ; this will expel all air.
The pressure should be light at first, but as the sub-
stance cools it must be increased, and as the gutta-
percha gets hard, great pressure ought to be applied
to make up for the peculiar shrinking qualities of
the material. A vice is very useful, and a screw-
press may be used, or a heavy weight will serve
the purpose. A compound of gutta-percha and
marine glue is in some respects superior to gutta-
percha. The gutta-percha is melted and the glue
stirred in. Marine glue is made from caoutchouc
and shellac, but it is best bought. When large
surfaces of woodcuts are to be done, sheets of
softened gutta-percha are generally used. A flat
plate is put on the top, and the whole is well com-
pressed. (See also p. 108.)

Fusible Metal " Clichee "—This is made by melt-
ing in a ladle five parts lead, then stir in three of
tin, follow with eight of bismuth. Well mix, and
granulate by pouring into water. This granulation
should be continued for several times until the
mixture is thoroughly made. This alloy will melt
at the heat of boiling water, and may be used to
copy wood articles without injury to them. The
coin or article to be copied is surrounded by an
edging of pasteboard, slightly oiled on the face, and
the fusible alloy poured in, pressure being resortedELECTROTYPES.

95

to as the alloy gets pasty. Care must be taken by
this method that the alloy is cleared of scum before
pouring. A better plan is to pour out the alloy
in a pill-box cover, or such-like receptacle, to clear
off the surface with a card, and when it gets pasty
suddenly press on the coin to be copied. A holder
should be attached by pitch to the coin.

Plaster of Paris.—This must be fresh, otherwise
it will fail to set. To insure the best work, it is
well to warm the plaster before commencing. A
flat dish of water should be prepared, and the
plaster sprinkled into it, then quickly pour off the
water, and work the plaster into a thin paste.
Pour it upon the oiled object, which should be
surrounded by a rim of pasteboard; air-bubbles
should be excluded. Allow it to set firmly, and
when removed bake it to expel all moisture. The
cast must be saturated with tallow or solid paraffin.
In doing this, prepare a shallow dish of the melted
substance, place the cast in it back downwards,
until the face shows that the soaking has reached
the face, when the cast should be removed. Too
much must not be allowed to soak in; if this does
happen, gently warm again until the excess is re-
moved. Allow to cool, and polish with blacklead
as usual.

Elastic Composition for Solid Objects.—This sub-
stance is made by soaking glue in water until soft,
melting in a glue-pot, and adding to it one-fourth
its weight of treacle. This composition will be
elastic when cool, and will be found suitable for96

ELECTRO-PLATING.

objects having much under-cutting. It may be
used also to completely surround the object, which
may be removed when the composition is set, by
cutting the latter, which will spring back to its
original position. It will be understood that this
substance is unfitted for use in liquids direct.
Prepare a vessel of sufficient capacity to hold the
article to be copied—say a bronze bust. Let the
latter be oiled to prevent adhesion ; if it is hollow
it should be filled with sand, and the opening closed
with pasted stout paper. Oil the containing vessel
within, and pour the hot mixture over the object
until it is covered; allow to cool overnight. Shake
out of the holder, and with a thin, sharp knife cut
open the mould from top to bottom. An assistant
can then withdraw the object while the operator
gently holds the cut sides apart. This elastic mould
is to be filled wTith a composition made up of bees'-
wax 5 lbs., deer fat 5 lbs.; melt slowly together,
add 8 oz. of a solution composed of bisulphide of
carbon 7 oz., phosphorus ^ oz. This is to be
poured in while as cool as. possible consistent with
its pouring well. When this duplicate of the
original bust is removed from the elastic composi-
tion, it may be stood in a taper vessel, and covered
with plaster of Paris; this is allowed to set, and
the wax model run out by heat. The interior of
the plaster cast is then washed out by

The Preparatory Solution.—Add to the above
phosphorus solution J oz. of wax, 1 oz. spirit of
turpentine, and a few grains of caoutchouc dis-ELECTROTYPES.	97

solved with an ounce of asphaltum in bisulphide of
carbon.

The Conducting Solution.—Dissolve i dwt. of
silver nitrate in a pint of water. To render more
sure, also wash out with a solution of 4 grains , gold
chloride in a pint of water.

In depositing upon such work, an anode should
be hung within the object, and a hole should be
made at the lower end to allow of the solution
escaping as it is poured in at the top. It is also
common to fix a series of guiding wires to serve as
anodes, but the best arrangement of these will be
suggested by the shape of the interior. In all
cases the guiding wires must be distributed about
the surface, and lead to the main wire from the
zinc plate.

The somewhat troublesome process avoids seams
in the electrotype, but solid objects may be
moulded from it in two portions by means of wax
or plaster of Paris. Bed the article to half its
depth in fine sand, and fix a few wires or wood
pegs around the object so as to project. Then
pour on the moulding substance, which may be
wax, allow to set, reverse the sand-box, and shake
out the sand ; trim the wax surface, leaving in the
pegs, and pour on the other side. When set,
separate the halves, polish up, after fixing wires,
and deposit; finally trim, and join the two halves
with solder.

Wax composition for such work may be made
thus:—Melt together three parts of yellow bees'-wax

H$6	ELECTRO-PLATING.

aad one part of stearine. Some electrotypers add a
little flake-white, but powdered blacklead is better,
as it assists in the conducting operation. A great
many small articles may be copied or moulded
from in this composition. When coins are copied
it is usual to do both faces, but not to join them to
form a real duplicate.

New Method for Producing Facsimiles of Coins
and Medals.—This method, the result of experi-
ments made by the author, aims at the production
of duplicate coins and medals in mixtures of tin
and lead, or, better still, fusible alloy, or alloys
containing bismuth. The coin is brushed over on
both sides with turpentine in which a little bees'-
wax has been dissolved. This is allowed to dry.
A piece of good writing-paper is steeped in melted
paraffin or in thin shellac varnish, and with a pair
of compasses a circle of the same size as the coin
is marked out. This disc is to be carefully and
cleanly cut out with a sharp penknife, and the
coin is to be fitted into the aperture thus made. If
care is taken, the paper divider may be got upon
its edge, and may be so fixed at the middle of this
as to divide the coin into two parts or discs. There
is no other preparation; the coin is simply sup-
ported in a square-bottomed stirrup of wTire and
deposited upon from an anode placed underneath.
When one side has received a deposit, the other is
to be turned, and this deposited upon. In this
way two heavy and strong deposits may be laid in
twenty-four hours or less. They will be separatedELECTROTYPES.

99

by the paper at the middle of the coin's periphery,
and if they do join a little underneath the paper,
they are easily separated with a sharp knife. By
heating the coatings rapidly, little difficulty will be
experienced in shaking the coin out, and in secur-
ing the two coatings in perfection. Their edges
are next filed round and even, and one of them is
placed in a pill-box cover just large enough to
hold it. A quantity of fusible alloy, well skimmed
and clean, is to be poured on the mould face,
skimmed quickly, and before it cools past a pasty
condition the other coating is quickly and firmly
pressed upon the alloy, so as to enclose a quantity
thick enough to fill the cavity. The excess will be
pressed out at the top, and may easily be separated
from the copy by cutting. This method gives a
very accurate copy with very little trouble. No
blackleading or other preparation is necessary in
the case of metallic coins or medals.

Coating, of Ferns, Grass, Flowers, and Insects.—
Dried grasses, ferns, lace, and such things may
be beautifully coated with copper. They are first
dipped for a few minutes in the preparatory solution
before spoken of, and then in the silver and gold
conducting solutions following it. The connection
with the conducting wire should be made before
dipping in the solutions. Silver and gold, as well
as copper, may be deposited upon these objects.

Electrotypes from engraved Steel Plates.—This
work requires considerable care, and the success-
ful results are of great value. The steel plate hasIOO

ELECTRO-PLATING.

its lines perfectly freed from ink. This is most
quickly done by boiling in solution of caustic
potash. Rinse out in boiling water, allow to cool,
and spread over the surface turpentine in which a
little bees'-wax has been dissolved; clear off, and
allow to dry free from all dust. Place upon a flat
surface (preferably stone or iron), and surround
with an edging of strip iron half an inch high.
The moulding composition is made of gutta-percha
2 parts, white wax i part, and lard i part; it will
require some time to properly mix, and for this
purpose a gentle and constant heat should be kept
up, with much stirring. Pour upon the plate,
allowing it to set for twelve hours. The mould
may be removed with care by cutting away any
overhanging parts. A little springing upwards
will release the surfaces. Great care is necessary
not to injure the mould. It is rendered conductive
by pouring over its surface a mixture of i ounce
phosphorus and i ounce of benzine in 2 quarts
of methylated spirit. The solution should be fil-
tered in case of sediment, and care is necessary to
observe that the plate is covered in every line by
gentle agitation ; pour off, and apply a solution of
nitrate of silver \ ounce, and glacial acetic acid
1 drachm, in a pint of pure alcohol. Gently agitate
over the surface of the mould until the silver is
seen to deposit all over; then pour off and wash
in distilled water. Four connecting rims (or a
greater number according to the size of plate)
should have been previously fixed in the edges of" STEEL " FACING OF PLATES.

IOI

the gutta-percha. Their ends should finish in
round rings or loops. All these loops are to be
connected by hooks to the main conducting wife.
As many as three cells should be employed to force
the deposit. A substantial layer of copper will be
deposited in a week, all over the plate, if the solu-
tion is properly supplied and worked with suffi-
cient battery power. A flat anode plate should
be employed for such surfaces, and its distance
from the mould may be from 2 to 6 inches. Care
is necessary to use only a filtered depositing solu-
tion, as any specks of dirt getting upon the mould
will destroy its use in printing. The necessary
separation may be easily made by warming the
copper plate. Any of the gutta-percha that may
remain (if too much heat has been applied), may
be removed with bisulphide of carbon. A little
rubbing with a soft brush or a piece of cotton wool
with the same liquid will separate any of the con-
ducting silver that may remain upon the electro-
type.

" Steel"-facing Electrotypes.—This is a valuable
process, by which an exceedingly hard film of
electro-deposited iron is thrown upon the face of
an electrotype. The advantage is that the plate
will last much longer, by reason of its extreme
hardness of surface. It has also the advantage of
printing from better than copper itself, and will
easily take vermilion, while copper prints it only
indifferently. This process, properly conducted,
renders the wearing out of a plate a difficult102

ELECTRO-PLATING.

matter, while the iron may be dissolved off and
redeposited without in any way wearing the lines.
The deposit must be very thin, otherwise it will
spoil the fine lines, but there is little fear of
overdoing the " steel face " if the work is watched.
Before proceeding to deposit the iron, it is neces-
sary to perfectly clean out the lines of the plate,
and then to chemically clean the surface before
placing in the bath. Caustic potash will be found
useful for this, and only a' very rapid dip of the
plate must be allowed to be given in the cleaning
mixture for copper; then well wash with water
only. (Sw Preparation.) «

Steel-facing Engraved Plates,—The deposition of
iron being employed but rarely for any other pur-
pose than this, and because the facing of electro-
types is a matter of much practical import, I shall
confine my remarks upon the deposition of iron to
the instructions here given.

The double chloride of iron and ammonia has
been found to be the salt best fitted for the deposi-
tion of iron from a solution electrically. The author
adds, however, to this process particulars of a
solution resulting from some researches of his, and
from a modification of the process of Prof. Bottger.
To make the usual solution, dissolve clean iron
wire, in coils, in hydrochloric acid until the acid
is satisfied; use a gentle heat at the close of
operations, because the acid will be weak. For
every 58 grains of iron dissolved, add 53 grains of
ammonium chloride to the solution. I have found"steel" facing of plates.	103

that the addition of a proportion of glycerine to the
solution diminishes its tendency to spoil. (Sprague.)

Another way is to dissolve 25 pounds of car-
bonate of ammonium in 17 gallons of water. The
iron is to be dissolved into the solution by im-
mersing in it a clean anode of charcoal iron,
connected to the copper pole of a battery of three or
four Bunsen cells. To the zinc pole attach another
iron plate, and test for deposit by occasionally
substituting a copper plate for the cathode.

To work the solution, let the anode be of char-
coal iron, the current about three Bunsen cells.
A deposit is not secured at once. It is necessary
to immerse the engraved plate for a few minutes,
take out, and brush well with fine whiting and
water. Immerse again, scrub at the end of five
minutes, and in four or five immersions a sufficient
deposit will be secured. Keep the solution up by
the addition of about half a pound of carbonate of
ammonium every few days. The best results seem
to be secured when the battery power is about
three cells, and the surface of plates in the cells
much larger than the anode or engraved plate.
I have worked a solution (referred to above) which'
keeps better than the foregoing. Dissolve 5 pounds
of ferro-cyanide of potassium, and 10 of the double
tartrate of soda and potash in 20 gallons of water.
Add now ij pounds of persulphate of iron, dis-
solved in a little water. Prussian blue is precipi-
tated copiously. Now gently add, drop by drop, with
stirring, a saturated solution of caustic scda until104

ELECTRO-PLATING.

the precipitate is redissolved and disappears. The
liquid is now clear, and of a yellow tint, and may-
be used immediately.

"Steel-faced" plates should be very carefully
washed in boiling water after removal from the
plating solution. Then wash in cold water with
brushing, dry off, rub with benzine, oil it, and rub
again. If not at once required, set aside with a
film of wax melted upon its surface.

Conducting Surfaces.—For general gutta-percha
moulds, the best and cheapest conducting surface
is the finest blacklead. That known as Nixey's is,
perhaps, the best of common kinds. Ordinary house
blacklead is almost useless, because it is so impure.
Perhaps the best possible composition is fine gas
carbon (battery carbon) pounded in a mortar to an
impalpable powder. If this can be obtained fine
enough, it answers better than most blackleads,
and is cheap enough. The instrument makers
generally keep a very fine quality of plumbago,
which is, of course, more expensive than the com-
mercial article. A good conducting surface being
of the greatest importance, care should be taken
to' well polish it at every point, and to give par-
ticular attention to the conducting wire, so that the
film of blacklead may commence upon the wire> and
extend unbrokenly over the mould. The brush used
should be of the softest kind. The blacklead
should not be wetted, but brushed on dry, and the
substance breathed upon while working up the
surface. Exposing the coating to the evaporationCONDUCTING SURFACES.

of spirit of wine will generally facilitate the
formation of a good surface. ' If there is under-
cutting, which cannot be well touched by the brush,
it will be be°>t to do the whole surface over with the
preparatory phosphorus solution and silver and
gold solutions (or silver alone, according to the
value of the mould) mentioned before. In work of
importance, and of a large size, the process of black-
leading is greatly improved by gilding the black-
lead. To gild, dissolve i part of gold chloride in
100 parts of sulphuric ether, and shake into the
bottle, mixing well, 50 parts of the best plumbago ;
expose the mixture to the sunlight, with frequent
stirring and shaking, until the ether has perfectly
evaporated. It is applied in the same manner as
blacklead. Plumbago may also be used with ad-
vantage in several moulding materials, to increase
their conductivity. It may also be mixed with the
finest white bronze powder. This has the property
(being tin, &c.) of coating itself by simple immersion
in the solution, and greatly aiding the formation of
a first deposit—it should be used chiefly upon large
moulds. Wires must be carefully fixed in mould-
ing materials ; in gutta-percha by warming and
pressing into the surface, and in plaster by arrang-
ing for fixing before the plaster is poured, or
while it is yet soft. Guiding wires should be led
from the main wire upon all surfaces larger than
two inches in diameter. They should lead into the
margin of the mould, and should beblackleaded over;
such wires should be finer than the main ones for con-io6

ELECTRO-PLATING.

venience of twisting, and the ends of some of them
should touch deeply cut parts of the mould, until a
deposit is there formed; always selecting such points
as are not likely to be defaced by the wire until a
coating is secured. In working with plates, such as
copper plates, to be faced, the wire is to be soldered
to the back.

A non-conducting surface is also required in
electrotyping, for " stopping" off the deposit where
it is not required. Copal varnish will be found to
answer all purposes in the sulphate solution, and
in the hot cyanide one the best quality of the same,
with the addition of rouge, allowing to dry well.
Solid paraffin is useful in cold solutions, and
shellac varnish may be employed. Accidental
finger-marks of blacklead should be varnished
over, as they are very troublesome if in contact
with the main coat or the wire.

Electrotyping Set-up Type'.—This process is some-
what similar to the reproduction of woodcuts.
The type is blackleaded, and the impression taken
as usual. Care should be taken that the mould and
anode are not nearer together than about 3 inches,
because the deposit finds difficulty in spreading to
a strong deposit in deep lines. American printers
employ this method of reproduction very ex-
tensively, and even in England stereotyping is
to a certain extent giving way to it. The repro-
duction lasts longer than one in " stereo" metal,
and the copper delivers the ink more readily.

Hints on depositing Copper.—The battery powerHINTS AND SUGGESTIONS.	107

required will depend in great degree upon the nature
of conducting surface. A plate of copper or other
metal to be deposited upon, can be coated in a few
minutes, and there is no trouble in making the
deposit spread. But blackleaded surfaces, espe-
cially of gutta-percha, plaster of Paris, and wax, are
sometimes troublesome, and are always somewhat
difficult to drive a deposit over. Tension in the
battery current is what is necessary in spreading
deposits upon refractory surfaces. This means the
joining up of a number of cells in series. The size
of thin plates is not of so much importance in
forcing the deposit. In laying copper upon metallic
objects three cells will be ample, but in dealing
with gutta-percha coated with blacklead, as many
as five or six may be found necessary if the con-
ducting-wire and branches from it are not very
carefully fixed, and the plumbago coating well
done. The anode in such cases should even have
a smaller surface than the article. As soon, how-
ever, as a complete coating, however thin, is obtained,
there is no use in wasting battery power, unless
the work is needed immediately ; but in laying the
main deposit, ordinary conditions should be adhered
to—the battery plates should be as large as the
anode, the anode as large as the article, and the
distance between the anode and article made as
small as possible. Rapid working is never at-
tained to in baths where the anode and mould are
far separated. The distances must, however, be
greater in the case of undercut moulds, or those108	ELECTRO-PLATING.

with pits, than in coppering flat plates or ordinary
woodcut work. Battery power should be regulated
to the work, but current may be regulated very
easily by the distance apart.

Rapid Practical Electrotyping.—I add to the fore-
going remarks some useful information which will
serve as a guide to, or explanation of, the way by
which the rapid and successful electrotypes from
set-up type and woodcuts are produced for such
high-class newspapers as the Illustrated London
News, Graphic, and other papers, where the illus-
trations are prepared, cut in wood, electrotyped, and
steel-faced, in the shortest possible time to meet the
exigencies of the public wants. In different shops,
different (slightly) processes are adopted, but the
result is not materially influenced.

To commence work, the type or the wood block
is thoroughly cleaned by means of turpentine and
a stiff brush. It is then dried, spontaneously if
there is time, or by means of boxwood or mahogany
sawdust if not. It is now dusted with the finest -
powdered and sifted plumbago. To prepare the
moulding material, which is simply bees'-wax and
finely sifted plumbago, melt good bees'-wax in a
thick copper pan, and stir in the plumbago very
slowly, to insure a very intimate mixture. The
best guide to the quantity will be the thickness of
the mass: it must not get quite pasty, and by
allowing a little more heat, it must be quite fluid.
Keep the mixture at a good temperature under
boiling, and stir well—this is to insure the gettingRAPID ELECTROTYPY.	' 109

rid of all moisture and air-bubbles. For pouring
the wax in, " chases " as they are called, or shallow
dishes of pewter or stereo metal are used. They
are of the required size to hold the work, and about
a fourth of an inch deep; they should have end
projections, with holes for hooks to hang in the vat.
The wax-moulding mixture, still very hot, is poured
into the chase, and allowed to spread of itself from
one corner. The chase is then placed on a level sur-
face, and allowed to become partly cool. As soon
as the wax is seen to have upon its surface a skin,
and begins to make cracks therein, gently skim the
surface. Allow the wax to become partly set, and
carefully lift on to it the prepared block or type.
Place in the press, and give a gentle squeeze. Lift
off again, and see if the block face has taken up any
wax; if not, dust very thinly again with plumbago,
and replace. Care must be taken, if no proper gauge-
marks are made beforehand, to so guide the sense
of touch that the block may " fall fair," or into its
proper position. Now apply a very heavy pressure
in the press ; the impression is now technically (in
some shops) called a " squeeze/' Remove and
examine the wax. It should be a beautifully perfect
copy in intaglio of the block or type. Dust the
" squeeze " with fine plumbago, and polish up with
a soft brush ; see that all loose or large particles
are blown off by the breath, and observe that a
good connection of plumbago is made to the
" chase " side.

The mould is now ready to be " hooked " and hungno

ELECTRO-PLATING.

in the solution to a rod connected to the zinc end
of the battery. The depositing trough employed
is of oak, well jointed, and lined with lead, or
asphalt, or marine glue. Its size is usually about
four feet long, with depth and breadth of two feet
and eighteen inches respectively. The usual copper
solution is made, per gallon, of one pound good
copper sulphate, and one pound of sulphuric acid—
dissolve the salt first; gelatine may be added to
make the mixture keep better.

The batteries employed are usually of the Smee
type—zinc and platinised silver plates. As many
as twelve zinc and silver plates are used—each a
foot square, placed close together, and the trough
filled with weak sulphuric acid—i acid to 100
of water. All the zinc plates go to one wire, and
all the silvers to the other. This battery usually
serves with one charge for about a week, and is
recharged by drawing off the old liquid with a
syphon. It acts simply as one cell of large surface,
as all the plates go into the common oak trough—
lined with lead or marine glue.

The anodes are of thick sheet copper, a little larger
than the chases to be coppered. The mould is hung
in the solution a few inches from the anode face.
In about ten minutes the deposit is observed to
slowly spread towards the centre. When this is
seen, a look-out should be made for pinholes, which
are caused by air-bubbles, and may be prevented
from forming by brushing off. If all is in good
order, the copper will be thick enough in fromRAPID ELECTROTYPY.

111

seven to ten hours. If time is short, keep the anode
nearest to the chase as soon as a complete deposit
is formed. This will press matters on quickly. The
deposit will be thick enough if a little stouter than
brown paper. As a matter of fact the deposits may
even be thrown on in much less than ten hours, if
two cells in series are used, and if the surface of
their plates is as great as that of the " squeeze,"
and even greater, it is surprising what may be
done in six hours. As soon as the complete coating
is laid, there should be no further trouble with the
deposition until it is thick enough. In warm
weather the work will be done in less time than in
cold.

When all is ready, remove the chase, wash with
water, cut away any copper round the edges which
may prevent the ready removal of the deposit, and
heat the chase over the gas, to loosen the wax,
when the electrotype may be lifted carefully off.
Place it face downwards on an iron tray with
handles, and brush over with soldering spirit
(hydrochloric acid saturated with zinc), and sprinkle
with cuttings of solder. Place the . tray in a flat
vessel of melted stereotype metal, until the solder
melts, when it may be spread with a soft rag and
spirit. This is called " tinning " the electro. Re-
move the tray, and arrange a kind of framework
or edging of iron bars around the copy to hold in
the stereotype metal wThich is to form a backing.
Pour on the clean metal to a depth dependent upon
the size of electrotype. For deposits a foot square112

ELECTRO-PLATING.

the backing should be half an inch or more thick,
and the smallest electrotype should have a fourth
of an inch of backing. Allow to set, and cut off
with the circular saw the edge-metal. Place in the
planing machine, and plane down to gauge.

An examination should now be made to find if
there are any depressions on the plate, or other
defects that might prevent the printing being good.
Depressions are brought up on the face by taps
from behind. The edges are filed bevel to " clear,"
and the plate is finally mounted on a block of
mahogany, or oak, if its size is considerable. This
block is, of course, gauged to the height of the
type. A little practice will enable an ordinary
intelligent man to turn out first-rate electrotypes by
this method.CHAPTER V.

Deposition of Silver.

Its Salts.—Of the many salts of silver, the nitrate,
oxide, chloride, and sulphide are the most common.

The nitrate is the most generally useful of these
salts, and it is important that the electro-plater
should be conversant with its manufacture from the
metal itself, as it is very usual to find it prepared
altogether in the factory, although it may be pur-
chased for very little more than the value of the
metal it contains.

The text-books often direct thus:—Dissolve grain
or sheet silver in nitric acid and evaporate; but
this is widely different from what is necessary to
be done in practice. The nitric acid must be pure,
and must have a specific gravity of at least 1*420,
otherwise it will not dissolve silver with sufficient
rapidity to insure success. It should be diluted with
one volume of filtered rain-water to four volumes of
the acid. This mixture must be warmed to about
ioo° F., and the silver, in sheet or grain, added to
it slowly and with care, not to cause violent boil-
ing, The operation should be conducted in a rather
tall vessel, so that the froth may not be lost. Care

Iii4

ELECTRO-PLATING.

should be taken to have the neighbourhood well
ventilated, or to conduct the operation in the open
air, and standing over the vessel should be care-
fully avoided by the operator, the fumes of nitric
acid being very injurious. The silver should be
cut into thin slips in case of sheet being used.
Should the mixture become unmanageable by boil-
ing over, cool it down by the addition of a little
cold water, and add the silver more slowly. As
soon as the acid is satisfied, and will dissolve no
more of the metal, evaporate it by placing the
vessel in boiling water, or applying heat to it
directly. Carry this on until the bulk is insig-
nificant, and set aside to cool and crystallize. It is
best to do this in the dark, or in an opaque vessel.
The resulting colourless crystals are nitrate of silver,
or u lunar caustic/' They should be free from the
odour of nitric acid, should contain as much as 63 \
per cent, of silver, and should be perfectly soluble
in distilled wTater. In purchasing nitrate of silver,
care should be taken to test its value before buying
largely. This is best done by fusing at red heat with
borax in a common crucible, washing and weighing
the metal, when the above value should be ex-
hibited; or it may, of course, be done by pre-
cipitating a solution of it by dilute hydrochloric
acid, washing and drying the precipitate. Nitrate
of silver should be kept in an opaque bottle, or in a
dark place, and care must be taken not to handle
it too freely with the naked hands. Its price varies
as that of silver, but it may generally be obtainedSALTS OF SILVER. '	115

at 4s. per oz. It is a by-product in various large
operations at chemical works.

Oxide of silver is generally prepared by adding
a solution of caustic soda to one of the silver nitrate,
until all the metal is precipitated as oxide. This
brown powder is washed and filtered. It is similarly
obtained by precipitation, with clear lime-water
and caustic potash. The wash-waters should be
preserved, as they contain a little of the oxide.
Care must be taken in the use of caustic potash, as
severe sores result from touching it with the naked
hands.

Chloride of silver may be readily obtained from a
solution of the nitrate by precipitating with com-
mon salt, or dilute hydrochloric acid. This should
be done with stirring, and the precipitate allowed
to settle slowly. It is silver chloride, a white,
flocculent powder, and must be kept in the dark.
The presence of impurities in the silver, especially
copper, is very quickly detected by a pink appear-
ance of the precipitate.

Cyanide of'silver may be readily prepared by
adding a solution of cyanide of potassium to one of
the silver nitrate. The solution of potassium cyanide
may be of strength about 2 oz. to the pint. It
should be added to the silver solution slowly, with
stirring, until no further precipitate is observed.
The resulting salt should be white, and is cyanide
of silver. It is quite insoluble in water, but will
freely dissolve in most of the cyanide solutions,
and in hyposulphite of soda solution, sal-ammoniac,ELECTRO-PLATING.

and ferro-cyanide of potassium. The same salt
may be obtained from the oxide or chloride of
silver, but the nitrate produces the purest cyanide.

Double Cyanide of Silver and Potassium.—This is
by far the most generally useful of the salts in
silver-plating solutions; and it is only necessary
to dissolve it in water to at any time obtain a
plating solution for the battery process.

Sixty-five parts of potassium cyanide in solution
will be required to convert into the double salt 134
parts of the silver salt. This is really the plating
solution, and only needs a slight excess of the potas-
sium cyanide to render it suited for work. But of
this solution further information is given in this
chapter.

Simple, or Immersion Silvering.—This art is daily
becoming of more importance, especially to ama-
teurs. The methods here given are selected from
those I have myself used, and may generally be
relied upon to produce good coatings if the direc-
tions , are rigidly adhered to. The solutions are
peculiarly applicable to such articles as brooches,
buttons, hooks and eyes, watch-chains, and articles
even as large as forks, tea-spoons, toast-racks, and
liquor labels.

Strict cleanliness must, of course, be observed
with the articles, otherwise the coatings cannot be
depended upon.

The simplest possible solution is that of the
chloride of silver in water, with the addition of
common salt. This is well suited to the silveringSIMPLE SOLUTIONS OF SILVER.	117

of dial-plates, and such goods as may be varnished.
Brass goods, when properly cleaned, take a good
coating, and may be exposed to considerable fric-
tion without injury. The mixture should not be
made thinner than cream, and should be applied
by rubbing upon the previously wetted article with
a piece of cork, or a rubber made of rag upon a
wooden handle. The rubbing must be continued
until the surface is uniformly silvered, when the
article should be washed, dried in sawdust, and if
possible varnished.

Another solution, yielding a better coating more
readily, is made up of chloride of silver, 1 part;
washing soda (common), 3 parts; common salt,
parts, mixed together with a little warm water
until as thin as cream. It will improve as it is
used, and may be replenished, as it gets exhausted,
with a little chloride of silver in solution.

Another solution is composed of silver chloride,
1 part; common salt, 8 parts; alum, 2 parts; cream
of tartar, 8 parts. These are mixed together with
warm water. When the surface of the article will
admit of it, rubbing should be resorted to, and in
the case of goods exhibiting much intricacy of
pattern the solution should be thinner, and the
motion more vigorous. In no case should the
fingers be used to apply such compounds. Soft
tooth-brushes are useful, as are also pads of cotton
or sponge.

A simple immersion solution, the particulars of
which are due to M. Roseleur, is well known to118

ELECTRO-PLATING.

produce the best possible simple immersion coat-
ings. Its preparation is, however, somewhat trouble-
some, although the labour is well repaid. Dissolve
4 parts of washing soda in 5 parts of water in a
deep vessel. Place in the bottom also a layer of
mercury about J inch deep, and into this let the
end of a glass tube dip, through which pass sul-
phuretted hydrogen gas (see Chemicals, until the
solution is found to redden blue litmus-paper,
when the passage of gas must be stopped. The
mercury is simply to prevent the tube end from
getting chocked up with crystals, and with care
might be dispensed with. Set the solution aside for
twenty-four hours, pour off the liquid portion, stir,
and test again with the litmus-paper. If decided
acidity is observed still, by the paper becoming
quite red, add more crystals until the paper is only
made violet. If no sign of acidity is observed, it is
too alkaline, and more gas must be passed through
it. All that now remains to be done is to add the
necessary silver, and this is best done by putting
in a solution (saturated) of silver nitrate, watching
the result. A precipitate will be formed, which
will almost at once dissolve again, and as long
as the solution redissolves the silver, it should
be added, until the redissolution becomes slug-
gish, when the mixture is ready for working.
This solution, if properly made, will be found to
produce a thick coating of silver, and will work
for many months. But its only slightly acid
condition must be preserved by the addition ofSIMPLE SOLUTIONS OF SILVER.	119

either gas or soda; with silver when this is re-
quired.

There is no necessity to rub this mixture upon
the articles. They must be left in it, moving about
occasionally, until the required coating is secured.
The coating is well suited to brass, copper, bronze,
and other goods of the cheap description.

A solution for simple immersion, to be used at a
boiling temperature, is, perhaps, better suited to
the general run of small goods than any of the
foregoing. It is composed of water, 1 gallon;
cyanide of potassium, 1 pound ; and 3 ounces of
nitrate of silver. It is usual to immerse the articles
in a basket, and to shake about until completely
silvered. Or any of the foregoing solutions may
be used with advantage at a boiling temperature.
An enamelled iron vessel should, if possible, be em-
ployed. Care should be taken that metals differing
so much in their nature as coppejr and zinc are not
immersed in such solutions, because a voltaic tend-
ency is at once set up, and zinc will probably be
deposited upon the other goods. It is found that a
solution in which much copper has been silvered,
and is green in consequence, works better than a
new one. It should be noted that the greater the
volume of solution, the better and quicker the re-
sults. For practical or professional purposes the
solution should never, if possible, contain less than
a gallon of water, and two gallons is a better work-
ing volume. The cost of this class of silvering is
very small, because the labour is small, and thei 2\J

ELECTRO-PLATING.

coatings cannot easily be made thicker than tissue-
paper, except in the solution of M. Roseleur,
w,hich, when properly made and attended to, may
yield plating of a very durable nature, and which
might bear favourable comparison with electro-
plating itself. A satisfactory explanation of the
increasing thickness of deposit in M. Roseleur's
solution was not at first easy to find. The plating
goes on without any apparent electrical action
until the desired thickness is laid, and the same
law wThich causes the metal to act thus also causes
the introduction of a little drawback in the work-
ing—for the silver is in part deposited upon the
sides of the vessel. Of course there is no waste
here, but attention must be paid to the amount of
silver so abstracted, so that the solution may not
be allowed to get poor in metal and unfit for work.

The obvious explanation is a chemical property
of the liquid foreign to common solutions. In
common simple solutions the action of plating is
undoubtedly electrical, by which a portion of the
immersed surface is dissolved, which, setting up
electrical disturbance, causes its equivalent of silver
to be deposited. This goes on until the article is
quite protected from further dissolution, when the
plating must and does stop, leaving only a thin
coat. But in the peculiar solution of which we
have spoken the action is chemical. Sulphur<?M
anhydride from the silver sulphite absorbs oxygen
to form sulphur^ anhydride, thus setting the silver
free; and this metal will deposit itself upon theSILVERING GLASS SPECULA.

121

nearest object, regardless of its nature, even upon
the porcelain vessel. It is probable that the sul-
phuric anhydride, as suggested by Mr. Gore, com-
bines with some of the soda of the undecomposed
portion of the sulphite, liberates sulphurous anhy-
dride, and forms sulphate and bisulphite of sodium.
(Comp. Silvering of Specula?)

Silvering Glass Specula.—Although the following
process is seldom touched upon in works of this
class, I have thought, judging from the number of
inquiries addressed to me about it, that it may
meet a general want of amateurs. It may be
needless to note that the process, albeit fitted for
other work, is mainly arranged for the specula of
reflecting telescopes and concave mirrors. It be-
longs to the subject of simple silvering, and I place
it for distinction at the end of the usual processes.

Four separate solutions are required:—

Solution a :—Dissolve 175 grains of pure silver
nitrate (crystallized) in 10 oz. of distilled water.

Solution b :—Dissolve 262 grains of pure nitrate
of ammonia in 10 oz. of distilled water.

Solution c .-—Dissolve 1 oz. of pure potash (pre-
pared by alcohol) in 10 oz. of distilled water.

Solution d :—Dissolve \ oz. of pure sugar-candy
in 5 oz. of distilled water, then add 52 grains of
tartaric acid, and boil in a glass flask for ten
minutes. Whien cold add 1' oz. of alcohol, and
then dilute with distilled water, so as to make up
the volume to 10 oz. for use in winter, and to 12 oz.
for use in summer.122	ELECTRO-PLATING.

These solutions must not be mixed together until
they are required for use, but as given they may be
kept separately, and in a dark place, indefinitely.

For use, pour into a graduated measure 4 oz. of
solution a> and then add to it 4 oz. of solution b—
call this mixture A.

Into a second measure—or see that the first is
clean—pour first 4 oz. of solution c, and then add
to it 4 oz. of solution d—call this mixture B.

When actually required, pour solution A into
the silvering vessel, and then stir in solution B
with a glass rod, so that the mixture may be good.
The effect will indicate whether or not the solu-
tions are properly made. The mixture should not
at first lose transparency, but should begin to
change colour in about thirty seconds, first to a
pinkish yellow, then brownish, and finally to a fine
black. Just prior to the solution turning pink, the
surface to be silvered is to be lowered into it.

This is Martin's process, and with care will be
found to afford more certain results than that of
Ackland, Draper, or the Sugar of Milk, particulars
of which it will be unnecessary to give here.

The vessel in which it is intended to silver the
speculum should be sufficiently deep to allow about
half an inch depth of liquid between the face of the
mirror and the bottom of the dish. In diameter
the vessel should be at least 1 inch larger than the
speculum—it is needless to say that this vessel
must be chemically clean. To prepare the work,
all extraneous dirt must be removed carefully,SILVERING GLASS SPECULA.	123

if possible by warm water. As the mirror is to be
supported face downwards in the silvering vessel, a
cross-piece of wood should be made to go across
the top of the latter. It is best to cement this to
the back of the speculum with pitch. Let the glass
be moistened with turpentine, and evaporate this
nearly off before applying the pitch, to insure the
adhesion of the latter. If the silvering vessel is too
deep, place a block of wood between the speculum
back and the wood strip, so that about half an inch of
space may be between the mirror and the flat bottom.
This will permit of the volume of liquid required to
be known, by filling with water and measuring.

To chemically clean the mirror directions are
here given, because they could not be conveniently*
classed with those relating to metals. A test-tube
is convenient as a holder for the rubbing-pad. Its
diameter should be about half an inch or over for
large specula. Fill it with cotton wool, allowing a
pad to project. Pour strong nitric acid upon the
mirror face, and rapidly rub it well over the surface
with the cotton wool. Now dilute the acid by the
addition of a little distilled water, and again rub
well all over the surface. Run water upon the
speculum for a few minutes until the acid is well
washed off, and finally well rinse with distilled
water. If the cleaning has been perfectly done, the
water will appear to cleave to the entire surface.
If purity of surface cannot be secured by the use of
nitric acid, dry up the surface with a perfectly clean
linen cloth, and apply a mixture of potash in water124

ELECTRO-PLATAN Gr.

(i oz. in 10) with an equal volume of alcohol.
Spread as before with a new pad, dilute the mix-
ture as before, and well rub. Finally rinse the
surface with a liberal quantity of distilled water,
and keep the speculum face downwards in distilled
water until the silvering bath is ready.

As soon as the solution is observed to begin
changing colour, let the speculum be immersed. It
is necessary to exercise care in doing this. It must be
slipped into the watery solution edge first. Care is
likewise necessary in removing any water that may
remain upon the speculum back, as it is liable by
falling down to give rise to streaks in the silvering.
Well note that no spots of dust get between the
speculum face and the solution, and that all air-
bubbles are broken. Keep the solution in gentle
motion for the first few minutes, until the film
begins to assume a definite thickness. The mirror
may also be gently rotated. It is of the utmost
importance that the surface should not be separated
from the liquid by any accident during the forma-
tion of the film, as the almost certain consequence
is a streak, or break of continuity in the silvering.
It will be unnecessary to continue the agitation
constantly after the film is laid. For purposes of
observation the silvering vessel should be of glass.
Allow the deposition to go on until all the silver
in solution has been deposited. This may be
ascertained by the solution being clean, and it will
be necessary to break through the silver film at the
edge to observe this. In warm weather the de-SILVERING GLASS SPECULA.	125

position is much more rapid than in cold. See
that the mirror is not allowed to remain longer in
the liquid than is absolutely necessary, as there is a
tendency to lay a whitish film upon the silver after
the solution is exhausted of its metal.

Well wash the surface after removal by allowing
distilled water to run over it. After washing, let
the surface dry, by resting the speculum with blot-
ting-paper beneath to absorb all water running off.
It is best to get this drying done quickly, by means
of a draught of air, but see that heating to attain
this object is carefully avoided. The drying may
be assisted by absorbing with blotting-paper the
water around the edges. In a damp atmosphere it
is advisable, as suggested by Messrs. Home and
Thornthwaite, to drive off remaining moisture by
exposing the mirror to a slight warmth at some
distance from a fire. This should be done just
before polishing.

Finishing the film requires some care, above all
to avoid grit getting into the polishing pads.
Make a pair of these by filling two pieces of extra
soft wash-leather about six inches square loosely
with cotton wool, and tying them into balls with
twine. Carefully dust the film with camel-hair
brush or cotton wool, and then rub over it with
one of the pads in short circular strokes four or
five times. This treatment will give strength to
the film. Spread and examine some rouge upon
clean paper, dust the other pad with it, and go over
the surface as before until the polishing is perfect.126

ELECTRO-PLATING.

This pad should be kept for future use in a bottle
or other place, free from dust.

All glass surfaces may be silvered in this way,
but the directions just given are peculiarly-appli-
cable to specula.

Silver-Plating by the Battery Process.—Numerous
patents were taken out many years ago for new
solutions for silver deposition. They are all more
or less valueless, as experience has shown, and time
has also conclusively proved to practical men, that
the double cyanide of silver and potassium, dis-
solved in water, afforded the best working solution.

Cyanide of silver dissolved in cyanide of potas-
sium is, howevef, a very wide definition of the
working solution. For the benefit of those who
require the plainest possible instructions in making
up silver solutions, my remarks are divested of all
chemical formulae, so that the merest amateur may
produce and work silvering baths almost as suc-
cessfully as the every-day plater.

It is common to suppose that the silver to be
used must necessarily be pure. This is not so, as
ordinary commercial silver, having copper in alloy,
works very well. I shall suppose that the nitrate is
made from the raw metal by the operator himself.
Particulars as to actual working quantities would be
out of place here, when one reader may require a
quart, and another a hundred gallons of solution.

The weight of silver in each gallon of really good
plating solution should be two and a half ounces.

This will serve as a guide to the weight of metalSILVER SOLUTIONS.

127

required for any given volume of solution. It will
be seen further on that this weight to a gallon may-
be deviated from considerably under certain con-
ditions, but there is no kind of plating that cannot
be successfully accomplished with this metal to the
gallon. I have placed well with one ounce to the
gallon, and also with five ounces, but in such cases
ordinary current and size of anode had to be de-
parted from ; and little satisfaction results from
working so widely of the composition which
lengthy experience has taught the plater to be
the best. For poor kinds of work, of the large
class, less metal may be used, and more for baths
required to be worked richly and quickly.

In dissolving the silver to form nitrate it ought to
be cut into very narrow slips. If sheet is em-
ployed, this may be conveniently done with a
pair of scissors; but if what is known as grain
silver is used, further division is unnecessary.

Take two parts of silver, add it gradually to a
warm mixture of four parts of strong nitric acid
and one part of water. Let this be done in a large
stoneware or glass vessel. The brown fumes of
nitrous anhydride are given ,off in great quantity,
and as they are very injurious, they should be
carried off by a vent, or the whole operation should
be conducted in the open air. It may be useful to
state that the weights of silver and nitric acid above
given are good for good silver and the best nitric
acid, but of a poorer quality of acid more must be
used to completely dissolve the silver, and the heat128

ELECTRO-PLATING.

must be greater. The action must be regulated by-
more or less silver, or a little water if it becomes
too violent so as to boil over. If too little acid is
employed, the fact will be indicated by its ceasing
to act upon the silver. When the metal is com-
pletely dissolved, evaporate the liquid portion
nearly to dryness by boiling, and set aside the
residue to cool and crystallize. Dissolve the result-
ing salt, nitrate of silver, in distilled or filtered rain-
water, allowing nearly a gallon to each ounce of
salt. Prepare also a solution, of equal bulk, or less,
of cyanide of potassium in distilled or filtered rain-
water. If the potassium salt is very good (over
60 per cent.: see Chemicals), half an ounce to the
pint will be strong enough, and if weaker one ounce.
Add this solution, with constant stirring, until a
precipitate of cyanide of silver ceases to fall as a
white powder. Waste must be avoided in doing
this, for if too much is added hastily, some of the
silver cyanide will redissolve, and will be difficult
to find again. To totally steer clear of the possi-
bility of waste, add the potassium cyanide solution
very slowly, and cease instantly the white precipi-
tate ceases to fall. If it is suspected that too much
of the cyanide solution had been stirred in, add a
little more silver nitrate, which will descend as a
white powder as before, as long as any excess of
potassium cyanide is present. Allow the liquid to
settle well down until quite clear. Pour off the
clear liquid, and dash in more distilled or filtered
rain-water, briskly stirring and allowing to settle,SOLUTIONS OF SILVER.

129

after which pour off again. Repeat this washing
a few times, with care not to lose silver in so
doing. Prepare next another solution of cyanide
of potassium (from three-fourths to one and a half
ounces to the pint), of bulk half a gallon to each
ounce of the silver cyanide, and add it to the latter
with constant stirring, allowing time for dissolution,
until all the salt is dissolved; then dilute the whole
to about half a gallon to the ounce of cyanide, with
distilled water, and add about one ounce to the
gallon of potassium cyanide to form free cyanide,
otherwise the solution would fail to dissolve its
anode with sufficient freedom. It is well after-
wards to filter the solution, through calico, into the
silvering vessel.

These are all the necessary directions for the
preparation of a solution by the chemical process
direct from the metal. It will be found best to
work from the metal in large operations, but for
small volumes it will prove more advantageous to
purchase the silver as nitrate, testing for quality, if
accuracy is desired, as before directed (see Nitrate
of Silver). All the wash-waters or residuary liquids
should be preserved when the operations are
large, because they generally contain some of the
silver in solution, and, if any insoluble substances
appear in making the solution, they should be pre-
served.

Several writers mention a method of preparing
the cyanide of silver from a solution of the nitrate
bypassing into it hydrocyanic acid gas. Although

K130	ELECTRO-PL ATINGr.

this may yield a silver cyanide of remarkable purity,
it is exceedingly dangerous, especially in the hands
of unskilled operators; the gas being diffusive, is
liable to be inhaled, with fatal results. Moreover,
the trouble is very much greater, and the same
result in purity may be attained to by using cyanide
of potassium of 85 per cent, purity and upwards
without danger. It may, however, be employed,
and perhaps with advantage, by very careful platers
who have by them a stock of otherwise useless
ferro-cyanide of potassium (" yellow prussiate of
potash" of the shops) and sulphuric acid. The
ferro-cyanide is* coarsely pounded, passed into a
glass flask, mixed with slightly dilute sulphuric
acid, and heated, the gas being led off by a tube
into the nitrate of silver solution, which must be
stirred until all the silver is down as cyanide. All
this should be done in the open air or where a good
draught can be secured, and the greatest possible
care should be taken not to inhale any of the gas.
This same process is very useful in recovering from
spent solutions some of their metals, but the mani-
pulation is slightly different.

Hyposulphite of silver in solution of hyposul-
phite of soda will deposit silver fairly well, but the
solution is only fitted for short experiments, as it
spoils by being exposed to light. Many writers
recommend it, but I cannot do so, as its silver,
although laid easily with the smallest battery power,
is so soon precipitated to the bottom of the vessel
on exposure to light. For short experiments orSOLUTIONS OF SILVER.	131

small pieces of work in the hands of amateurs, it
may be made up by dissolving the chloride of
silver in a solution of hyposulphite of sodium.

Ferro-cyanide of potassium is used to a limited
extent by some platers instead of the cyanide. Its
use cannot be recommended, as it loads the solution
with a foreign salt, and it would appear that the
silver deposited from such a solution is very liable
to strip. It is, therefore, false economy to employ
the yellow prussiate of potash.

It is not uncommon to find cyanide solutions
made up chemically, and differently from that de-
scribed. It is not uncommon, for example, to simply
make the solution by stirring the oxide or carbonate
of silver into a solution of potassium cyanide ; and
although this will enable the operator to dispense
with the use of cyanide of potassium in precipitat-
ing the silver from its solution, and to employ in
its stead caustic potash, carbonate of potash, and
even common salt, it has nothing "to recommend it,
and is, again, an example of false economy. It is
still necessary to use the same amount of potassium
cyanide as by the ordinary cyanide process. When
oxide of silver, for example, is placed in a solution
of cyanide of potassium, it needs one equivalent of
cyanide to convert it into cyanide of silver, and
another to dissolve this cyanide of silver as before.
And it is, moreover, working in the dark, although
the plan maybe useful to those who do not wish
much handling of potassium cyanide. But such
solutions never work satisfactorily for a great length13 2	ELECTRO-PLATING.

of time, and have many obstructions in the shape
of useless potassium salts, which may or may not
do harm according to the condition in which the
solution is to be worked. Such a salt as oxide of
silver going into a solution of potassium cyanide
must lose its oxygen, which simply goes to form
with the potash salt caustic potash, which is at
least of no use, while the potassium chloride result-
ing from so foolish a mixture as chloride of silver
with the cyanide solution, almost stops successful
working and dissolution of the anode. These bad
effects are not apparent at once, but increase as the
work goes on.

The standard cyanide solution may also be made
by the battery process; that is, instead of the silver
being prepared chemically first, it may be dissolved
into the solution by the current from a cell or two
of any type of battery. This process is exceedingly
handy to amateurs and others requiring only a
small volume of the solution, and is certainly
preferable in such cases to special chemical prepa-
ration ; also where all operative skill is wanting,
because no loss of metal can result, and there are
no wash-waters to preserve. It is only necessary
to prepare a solution of potassium cyanide, of
strength about four ounces (quality at least 50 per
cent.) to the gallon. Then suspend a large sheet of
silver to dissolve, and connect it to the copper or
carbon pole of the cells. Suspend likewise a bright
silver strip a few inches off, connect to the zinc pole,
and thus pass current until about 1 \ oz. of silver toSOLUTIONS OF SILVER.

133

the gallon has disappeared. If it is required to
have more metal than this, add more cyanide in
solution, or less if a poorer solution is required.
The best guide is to pass the current until the cathode
receives a good coating of silver in a few minutes.
This solution may be worked with the dissolving
sheet as an anode, in the same way as large volumes
are worked. Unless the actual percentage of
actual cyanide be known, it is difficult to state the
quantity of free cyanide necessary. A good test is
to work the solution with the anode for a little time,
and if the anode is not bright and clean, too little
free cyanide may be suspected, and more should be
added. As a matter of course a strong current
should be employed in making such solutions. It
is objected to this method that it sets free caustic
potash in the liquid. This is true, and it eventually,
by absorption of carbonic acid from the air, becomes
carbonate of potash. It does no harm as far as
experience has shown, but it does no good. It is
certainly more objectionable in large volumes of
liquid than in small ones. Notwithstanding this,
many electro-platers make up their solution by the
battery process. It proves to be exceedingly useful
to those who take the trouble to test the cyanide
employed. There is also an advantage in this way
of making up a solution, as very little trouble is
appreciated in giving to it just as much metal as
may be wanted. The equivalent of cyanide of
potassium is 65, so that 65 parts of the pure cyanide
ought to be in the solution with 134 parts (the134

ELECTRO-PLATING.

equivalent of cyanide of silver) of silver salt. Over
and above this there should be present about 50
parts more of potassium to form free cyanide, with-
out which it would be impossible to work.

It is not uncommon to employ two solutions in
silver-plating, especially in treating the cheapest
kind of goods. Where the standard work is really
composed of inferior articles, it is probably more
economical to first " whiten," as it is terrtied, and
then finish in another liquid. The process is well
suited for cheap and rapid working. To make a
" whitening " solution, dissolve about two pounds
of cyanide of potassium (over 50 per cent.) in one
gallon of rain-water; add afterwards half a pound
of carbonate of soda, with stirring; and add last,
four ounces of cyanide of silver. Whiten the
articles in this with a current of high tension—
five to eight Smee cells, six Bunsens, allowing
the anode to be quite near to the goods. As a
rule, when the current is strong, they will whiten
instantly, and are to be removed for finish-
ing in the other solution, which is made up by
dissolving four ounces of cyanide of potassium and
two of cyanide of silver in a gallon of distilled
or filtered rain-water. Employ a current of lower
tension to finish, and let the cell be large, so that
the work may not go on so rapidly, but let the
anode be near to the articles. The poorer kinds
of articles may thus be silvered without the neces-
sity to amalgamate or " quick" in a mercury
solution. (See Preparation.)QUALITY OF SILVER SOLUTIONS.	135

It will be unnecessary to extend this portion of
the work by quoting the solutions of the various
patentees. Theyare all, curiously enough, inferior
to the standard cyanide solution in working, and
the greater part of them were devised before platers
had become sufficiently acquainted with the good
properties of the double cyanide of potassium and
silver. I leave the particulars I have given of this
solution in the plater's hands with every confidence
in his working of it; the results are always good, and
the trouble small compared with other solutions.

Quality of the Solution.—As I have before stated,
different platers employ solutions differing widely
in the composition. This arises in great part from
their work being of different kinds, or from their
manipulatory skill being good or bad. Some
platers employ a solution as poor in silver as half
an ounce per gallon, while others use one as rich
as four or five ounces to a like volume of solution.
Different factories employ different modes of work-
ing, and such great discrepancies would lead even
amateurs to infer that the limits within which
successful work can be turned out are very far
apart. This is true to a certain extent, for by
altering the battery power and anode surface to the
liquid, it is possible to plate such a metal as copper
with either of the above strengths of solution. For
ordinary work, however, the proportion I have laid
down (two and a half ounces to the gallon) should
be adhered to as nearly as possible. The amount
will probably vary as the work is carried on, but136

ELECTRO-PLATING.

every care is necessary to employ such proportion
of free cyanide as will assist the anode plate to
throw off just as much silver as is laid upon the
articles. This is really the secret of good working
and keeping a solution, when once made, in good
order for years.

Free cyanide is a point to be looked to constantly.
The proportion of free cyanide in a good solution
should be as nearly as possible equal to half the
weight of the silver. If less than this is employed
the anode will not dissolve with sufficient rapidity
to supply the metal laid upon the goods. If more
is present, the anode will dissolve too quickly, and
there is a risk of the silver being dissolved off the
goods nearly as quickly as laid. (See Management
of Solutions,)

" Bright" Silver Plating,—This is a process em-
ployed in the plating factory by which a brilliant
appearance or finish is given to the goods after they
have been plated in the ordinary way. It saves a
great deal of trouble, because the surface is finished
as if it had been burnished. It is questionable
whether the solution is of use to the amateur, as
it does not appear to work well in very small
volumes.

To make this solution, place a quart of ordinary
plating solution in a special bottle, add' to it four
ounces of liquor ammonia, two of ether, and four
of bisulphide of carbon. Shake well, and stir in
an ounce or two of this mixture to every twenty
gallons of plating liquid it is required to " brighten,"BRIGHT SILVER PLATING.	137

about twice a day. This is done as the bath is work-
ing. All the bisulphide of carbon mixture must
not be added at once—this would spoil the whole
solution. As the plating goes on, a little should
be stirred in after the day's work, as mentioned.
It is of the greatest importance to use as little as
possible of this destructive bisulphide of carbon,
as it is very apt to ruin the solution altogether.
And no solution should be thus " brightened"
that it is required to plate ordinarily with again,
as it will be unfit for that purpose. If the
articles become spotted or streaked with a bad
brown colour, it indicates that too much brighten-
ing liquid has been used, and the best plan probably
in this case is to work upon a silver cathode until
the excess is worked off. Bisulphide of carbon by
itself will produce the effect, but the mixture given
will be found more satisfactory.

A stronger current than usual must be passed
in a brightening solution. The action is slower
than in ordinary solutions. As a rule the effect is
first apparent at the lower end of the article, and
sometimes as long as twenty minutes passes before
the whole surface is bright, but the time greatly
depends upon the battery power. If a valuable
article is being spoiled by becoming brown instead
of bright, remove it and dip for a few seconds in
nitric acid, and try again. But as a rule too much
bisulphide of carbon spoils the solution for several
days. It is, in fact, an exceedingly risky process in
the hands of the inexperienced, and this is the138	ELECTRO-PLATING.

chief reason why amateurs seldom succeed with it.
For small volumes, such as a gallon of solution, a
few drops of the brightening mixture will be
enough every evening, with stirring. It is always
necessary to remove all traces of the brightening
liquid after removal from the solution by rinsing
in boiling water. If this is not done the surface
will discolour. The skin thus given to plated
goods is very hard, because the rate of deposition
is slow. M. Planters method of brightening is to
add sulphide of silver to the solution instead of
bisulphide of carbon.

Management of Solutions.—The standard cyanide
splutions are liable to continual change. They are
apt to change in strength, through an insufficiency
of cyanide or unsuitable battery power, and the free
cyanide is liable to change in quantity from the
latter cause. Experience shows that a new solution
does not deposit silver so freely as one in constant
use. Indeed, difficulty is often experienced in
working a new solution, which objection vanishes
gradually as the work goes on. If care is taken
the solution will improve until it has been at work
daily for a year or two, when contamination with
base metals and other impurities generally spoil it.

The anode should be pure silver sheet, with an
area as great as that of the articles to be plated,
and connected to the copper pole of the battery. It
should show when working a grey surface, and
when the current is stopped a white surface. If the
anode is white while the work is going on, thereMANAGEMENT OF SILVER SOLUTIONS. 139

is too little free cyanide. Should the anode show
a brown or discoloured surface, there is too little
cyanide in the free state, and more should be stirred
in. If the anode is too large in proportion to the
articles being plated, too much silver will be dis-
solved into the solution, which evil will be aggra-
vated by too large a proportion of free cyanide; and
if, on the other hand, the anode is much smaller, too
little metal will be dissolved, and the solution
robbed of its stock. This will be aggravated by too
little cyanide. Impurities are usually dust, acci-
dental dirt, impurities from the anode, metals
corroded while being plated—this latter is usually
caused by too weak a current, and the work being
done too slowly.

These impurities rise in the solution as soon as
any disturbance is caused, settle upon the surfaces
being plated, and spoil the work. They produce
vertical streaks, ending in a round mark. Filtra-
tion should be resorted to when the solution gathers
impurities. To continuously produce good plating,
the solution should be well stirred up at the close
of the day's work, and motion should be given to
the articles while being deposited upon. Indeed,
the latter precaution is imperative in most solutions
for a reason which I shall explain. At the anode
surface there is being continually formed the double
cyanide of silver and potassium. This salt going into
solution, is heavier than the liquid, and descends;
while the cyanide of potassium set free at the
surface of the articles by the silver leaving it, is140	ELECTRO-PLATING.

light, and tends to ascend. The result is, that, if
mixing is neglected, the articles are apt to be well
plated only at their lower extremities, while the
anode will probably be cut nearly through at the
surface of the liquid, through the excess of free
cyanide near the surface. It will thus be obvious
that strong solutions require more frequent attention
than those poor in silver, because the heavy silver
salt has a constant tendency to descend. The
solution should have added to it water to make up
for loss by evaporation and other causes, and it is
best to add any necessary free cyanide with this
water. Never stir up the solution before commenc-
ing to work, because the impurities always present
rise and take a long time to settle. If the deposi-
tion goes on very slowly, it will generally be
caused by too small a proportion of silver. This
may be added in the form of cyanide, but it is much
better to give more anode surface, and dissolve the
required metal in by these means. Poverty of
metal is often indicated by the deposited silver
having a grey or dead appearance, and the work
going on sluggishly—that is, if the anode indicates
that there is a sufficiency of free cyanide. Free
cyanide is lost slowly by the carbonic acid of the
air acting upon it and converting it into carbonate
of potash.

If the articles being plated are bad in colour, of
a dirty grey or brown, it indicates, in all proba-
bility, that the current is too strong. This is best
remedied by simply placing the anode farther awayMANAGEMENT OF SILVER SOLUTIONS. 141

from the articles. It is also well to note that this
may be caused by an excessively weak current,
and a deficiency of free cyanide. This appearance,
however, is generally found upon such metals as
tin, lead, Britannia metal, and white alloys gene-
rally, and seldom upon copper or brass.

A test for the free cyanide will be useful. I select
one of many practised. Put in a tall glass vessel
twelve ounces of the solution to be tested; make a
solution of half an ounce of crystallized silver nitrate
in five ounces of water, and add it to the solution
in the glass with stirring. Add very slowly the
latter half. A precipitate will form ; if it dissolves
quickly, there is a deficiency of silver or too much
free cyanide. If it will not all dissolve after stir-
ring, there is too much silver or too little free
cyanide. As a matter of course there must be too
much cyanide when there is a deficiency of silver,
for it is in reference to the silver that the free
cyanide must be viewed.

Strong solutions are always more difficult to
manage in hot weather than weak ones, especially
if they contain much free cyanide. Such solutions,
and at such temperatures, must be kept in almost
constant motion, by the goods being moved to
and fro. This is generally done in factories by a
mechanical contrivance, variously made, by which
motion is given to the articles from the machinery.
Sometimes the frame which suspends the plating-
rods is mounted upon four small wheels, which
ride upon rails fastened to the top edge of the vat,142	ELECTRO-PLATING-.

and other more simple contrivances are in use, but
they are to a great extent unnecessary if attention
is paid to stirring up and well mixing the solution
every evening after the day's work is done. If this
is regularly done, and the solution is still found to
act more upon some parts of the articles than upon
others, the fault must be in the solution, which is
too strong. Solutions that are too dense may be
quickly brought down by the addition of water only.

Test for Density of Solution.—The operator should
be provided with a hydrometer, by which the specific
gravity of any solution may be quickly ascertained.
The specific gravity of the solution may vary. It
should not, however, get below 1*042, or above
1*114. It is convenient to take a reading of the
specific gravity when the solution is found to be
working well, and to keep it as near to this as
possible; or a little over, on account of the accu-
mulation of foreign matter. Such tests should
always be taken in the evening, after stirring up.

These directions all point to one conclusion,
which is that when we have obtained a good work-
ing solution, every endeavour should be made to
keep it so, and to carefully avoid anything which
might chance to alter its constitution; to avoid
the accidental contamination of it by foreign or
base metals, or by accident, or by efforts to improve
it, which are not indicated plainly in the preceding
remarks ; above all, avoid the use of bisulphide of
carbon if possible, and never attempt to " Irighten "
a solution intended thereafter for standard silvering.MANAGEMENT OF SILVER SOLUTIONS. 143

If the anode rapidly disappears, a test should be
taken of the amount of silver being laid. Thus,
by weighing the anode and the goods before
plating, and again after plating, it is easy to ascer-
tain whether or not too much or too little has been
dissolved off the anode. The diminution of weight
from the anode should correspond closely with the
increase of weight in the goods. If the anode has
lost much more metal than the goods have gained,
there is too large a percentage of free cyanide, and
if the reverse, there is a deficiency of free cyanide.
To a certain extent the solution will right itself, or
correct its own fault, in the first case, if some water
is added to keep the specific gravity down as the
metal is being dissolved. This, of course, results
in the solution being augmented in volume. Strong
solutions require more stirring and general care
than weak ones, and a strong solution will be
made weaker by exposing to it less anode surface.
Some platers* £.dd liquid ammonia to the solution
when the silver is of a bad colour, or too yellow,
but it should be sparingly employed, and never
used unless the solution is in good order otherwise.
Always correct ordinary faults before trying the
addition of foreign substances to the solution.

Time required in Electro-plating.—The time re-
quired to plate ordinary goods varies considerably
in different solutions and with great or small
battery power. It is also dependent upon the
thickness of deposit required. A coating as thick
as thin writing-paper (one ounce per square foot) is144

ELECTRO-PLATING.

considered excellent work, and this can generally
be laid in about ten hours, half this thickness in
half the time, and so on—this is with one large cell.

Battery Power required.—As a rule, one cell will
be sufficient in ordinary plating, and of whatever
form it is, its plates must have an area about equal
to that of the immersed anode. The area of zinc
in solution may be regulated to the work doing.
If the articles present much irregularity of surface,
especially indentations or deep under-cutting, the
distance between the anode and cathode must be
greater than usual, and in such cases it is generally
wise to employ two cells, so that the extra resist-
ance may be overcome. (See Batteries.)

Cost of Silver-plating.—This will depend in a
great degree upon the amount of work done—or
the scale of operations. Including silver and work-
ing expenses, silver can be laid upon all ordinary
goods at about 8s. per ounce—or foot of surface.
This is for really good work, and the figure will
vary considerably in different places. If the work-
ing expenses are low, they may be laid down as a
fourth of the cost of silver deposited. Inferior
goods can be silvered at an exceedingly cheap
rate. By the simple-immersion process, which is
peculiarly applicable to small articles, buttons,
nails, hooks and eyes, and suspension chains can
be silvered at about 3d. a pound. But the silver
is a mere covering. By the battery process such
goods as teapots, sugar-basins, and silvered flagons
can be properly plated, labour included, at aboutORNAMENTATION OF SILVER.	145

6s., while a dozen of dinner forks can be properly
plated for 4s.

But it is always a difficult matter to give exact
figures, as different platers require different profits.
These figures refer to the work as done by the
plater to the " trade"—the u trade" being the
manufacturer of the goods, who generally sends
them to the professional plater for treatment.
There is unfortunately no check upon the English
plater, nor do the public know what they get in
purchasing electro-plated goods. Such a state of
things is not allowed in France, where every article
is stamped to indicate the quality of the plating.
This is done by an officer appointed by the govern-
ment, the articles being weighed, before and after
plating, in his presence.

u Oxidized" Silver.—This effect is produced by
laying upon the silver a film of sulphide of silver,
or it may be done by a film of platinum, which is
not the cheapest but the best way. The appear-
ance may be as light as a steel grey, and from this,
through all the shades, down to nearly black.
Make a solution of perchloride of platinum, and
brush on while hot. It is also better to heat the
article. If the solution is weak, and the tempera-
ture low, a steel grey will be given, and according
to the strength of solution and its temperature
will the colour vary to nearly black. The deepest
effect is produced with a saturated solution at a
temperature of boiling water. It may be necessary
to remove a white appearance outside the coating

L146	ELECTRO-PLATING.

by dipping in weak liquid ammonia. The appear-
ance of frosted silver may be given to silver articles
by depositing upon them a mere blush of copper
from a sulphate of copper solution, and over this
an exceedingly thin layer of silver. The articles,
as they come from the solution in ordinary plating,
have a very pleasing dead white or " mat" appear-
ance, which may or may not be left upon them.

A Blue-black Effect.—This is produced by treat-
ing with a solution of potassium sulphide (liver ot
sulphur of the shops). The solution must be hot,
and should be freshly prepared.

A Pink Effect.—A solution (saturated and hot)
of chloride of copper will produce this. The article
should be afterwards well washed and dried in saw-
dust. (Fearn.)

" Stopping-off" Composition.—When it is required
to protect any portion of an article from the plating,
or upon which any of the above effects are pro-
duced, good quick-drying copal varnish may be
used in plating, and in hot solutions the same with
the addition of various substances, such as peroxide
of iron (jewellers' rouge) or peroxide of manganese.
The best varnish, however, for use in hot solutions
is composed of plumbers' resin, 10 parts; yellow
bees'-wax, 6 parts; fine sealing-wax, 4 parts; polish-
ing rouge, 3 parts. (Gore.)

" Finishing" Plated Goods.—If the colour is not
good, dip in a weak solution of cyanide of potas-
sium, rinse in boiling water, and dry in boxwood
sawdust. If the general dead-white or " mat" ap-ANALYSIS OF SILVER SOLUTIONS. 147

pearance is to be left upon the goods, dip at once
in boiling water, and dry in boxwood sawdust. If
the articles have been plated in the ordinary solu-
tion, and it is intended to have them bright,
polished, or burnished, dip in boiling water, dry
and scratch-brush them with the ordinary brush.
Hard hair-brushes may be used for this purpose in
the hand. Bath-brick may be used with water,
whiting, rotten-stone, and finishing with rouge.
The burnishing is done with steel or agate bur-
nishers, generally of an oval shape, and the strokes
must all be in one direction. Stale beer, or even
soap and water, may be used to make the burnisher
work well. It will spoil the work to cross the
strokes, and all ribs must be burnished down.
Finishing is, in fact, almost^^SaSalp^a^^and in
electro-plating works	nothing\felse.

(See Preparation^) //	"9^ 1-

Analysis of Solutions.—I add	ioregoin|f the

following particulars of newmetfei^Js bycwjdfch the
composition of a solution rp^y^b^.^kown. A
known measure of the	^largely diluted

with water and raised to boiling. Sulphuretted
hydrogen (see Chemicals) is then passed into it, or
sulphide of ammonium gradually added. The
silver goes down as a black sulphide, which filters
and washes well, and, according to the books, is
free from copper and zinc. This, however, is not
the case in every instance, as any zinc which may
be present is sure to be thrown down. On this
account I never weigh the precipitate, but treat it148

ELECTRO-PLATING.

further. The washed sulphide of silver is rinsed
off the filter into a flask or beaker, and treated with
excess of bromine water, which converts it rapidly
and completely into silver bromide. If any sulphur
appear to have separated, a drop of bromine should
be added to the residue, so as to insure complete
oxidation. Now add boiling water and wash the
silver bromide, dry, fuse, and weigh it. This will
indicate the percentage of silver, the most impor-
tant point. The cyanide may be tound as before
directed for free cyanide.

Recovery of Silver from Spoilt or Old Solutions.—
The wet way is generally to precipitate the silver
as chloride by the addition of hydrochloric acid,
washing and drying the precipitate, and fusing
with carbonate of potassium and saltpetre. Great
care is necessary in precipitating thus. Hydro-
cyanic acid gas is given off, which must be strictly
avoided, and for this reason the operation should
be performed out of doors. It is better to evaporate
the solution to dryness and to fuse the residue,
washing the fused mass free of the potassium
cyanide. The first operation must be conducted in
a very tall vessel, because very violent action re-
sults from the addition of hydrochloric acid. The
process recommended by Mr. Sprague is as fol-
lows —Place the solution in a large flask fitted
with a safety funnel and delivery tube, and connect
to this by an india-rubber pipe a wide glass tube,
which place in another vessel, so that its end dips
half an inch or so under a solution of nitrate ofRECOVERY FROM SILVER SOLUTIONS. 149

silver. Now add sulphuric acid gradually by the
safety funnel, allowing the effervescence to subside,
and shake the flask occasionally; continue adding
acid as long as it produces any fresh precipitate.
Then, by means of a sand-bath, heat the flask and
keep the solution boiling as long as a precipitate
continues to form in the other vessel. This pre-
cipitate is pure cyanide of silver, and only needs
dissolving in cyanide of potassium to form a fresh
solution. The precipitate in the flask is also
cyanide of silver, but not pure, though sufficiently
so for use in most cases; if it is preferred it can be
reduced by zinc and hydrochloric acid, or dried
and fused. This process saves the cyanide of
potassium otherwise required to precipitate the
silver. The author suggests, as advanced by Mr.
Sprague, that this process might also be useful in
preparing solutions from the beginning, as in-
cluded in the directions before given, by placing a
solution of cyanide of potassium in the flask, and
distilling over the hydrocyanic acid into a solution
of nitrate of silver.

It will be observed that, as cyanide of potassium
plays so important a part in practical silver-plating,
a great many of the directions I have given are
subject to modification as to the weight of this salt
used. Although the subject scarcely belongs to
this section of my little work, but to that devoted
to necessary remarks upon the required chemicals,
a caution not to accept the chemist's computation
of the percentage of actual cyanide in the salt is150

ELECTRO-PLATING.

quite necessary. This salt is commonly sold of as
poor a quality as 25 per cent., and unless precau-
tion is taken mere rubbish is easily mistaken for
good cyanide. It should never be under 45 or 50
per cent. (See Chemicals.)CHAPTER VI.

Deposition of Nickel.

Its Salts.—The generally used salts of nickel are
its sulphate, nitrate, chloride, oxide, and carbonate.
Commercial salts, the oxalate and sulphate.

Sulphate of Nickel.—This salt is most commonly
prepared by slowly heating oxide or nitrate of
nickel in plenty of diluted sulphuric acid until it is
dissolved, and then evaporating the acid by heat
nearly to dryness, and setting aside to cool and
crystallize. Sulphate of nickel is easily soluble • in
water. Its price varies with that of nickel, but it
may be stated at about 2 s. per oz. in small quan-
tities.

Nitrate of Nickel.—Dissolve metallic nickel or
its oxide in diluted jiitric acid, gently heating.
When completely dissolved, evaporate off the acid
and set aside to crystallize. It is a green salt.

Chloride of Nickel.— Make a solution of nickel
nitrate, add a large percentage of hydrochloric
acid, and evaporate, or simply dissolve the metallic
nickel in the acid and evaporate. Chloride of
nickel is also a green salt.152

ELECTRO-PLATING.

Oxide of Nickel.—This may be produced by
making a solution of the sulphate or nitrate, and
stirring in a strong solution of caustic potash or
soda. A precipitate will fall, which is the oxide, a
black substance. Or the same salt may be made
by heating to redness in a crucible the nitrate of
nickel.

Carbonate of Nickel.—Carbonate of soda is gene-
rally used to produce this; by adding its solution
to one of any salt of nickel a precipitate is thrown
down, which is carbonate of nickel, a greenish
powder.

Metallic Nickel is generally very impure. It
contains a large percentage of silicon and some
carbon, so that on dissolving it in acids a black
sediment is thrown down, from which the liquid
portion must be filtered if clean salts of nickel are
required. It also contains a little copper. Nickel
is readily obtainable commercially, but it is usually
in the form of grains, as reduced by the common
process. Its price in this state will be about ios.
per lb., and in smaller quantities it would probably
be 15s. Much difficulty is frequently experienced
by depositors of nickel in the small way on account
of the anode required. A nickel anode is abso-
lutely necessary in working the best solutions;
they will not work steadily with a platinum plate,
as is frequently supposed, even although the lost
metal should be replaced regularly. A contrivance
for utilising grain nickel as an anode, consisting of
a flat case of carbon plates pierced with holes, hasSOLUTIONS OF NICKEL.

153

been patented in New York, but a flat case of
platinum wire gauze in the front, and carbon or slate
at back and sides, will be found better, and more
easily used. Nickel in thick plate for anodes is
procurable on the large scale; it should be as pure
as possible.

Nickel is not very easily deposited, especially by
the simple-immersion process. M&ne employs the
method of depositing it upon iron, steel, copper,
brass, and lead by contact with another metal in
the solution. The metal employed is usually zinc,
of which a strip is tied loosely to the article on
immersion in the solution. Chloride of zinc, in
boiling neutral solution with fragments of nickel
present, is the mixture employed. If the solution
is allowed to become acid, the deposited metal will
have a bad and dull appearance, which is not
readily worked off by the scratch-brush.

Another solution for the deposition of nickel by
contact with zinc is made by making a saturated
solution of zinc chloride in a copper pan, adding to
this twice its bulk of water, boiling for a few
minutes, and redissolving any precipitate which
may form by stirring in a few drops of hydrochloric
acid. Some fragments of zinc are then thrown into
the pan, which cause zinc to be thrown upon the
vessel as an adhesive deposit. Sulphate or chloride
of nickel is then stirred in until the mixture is quite
green, when the solution is ready for use. It is
used boiling, and the coating will take about twenty
minutes. If a thick coating is required the articles154

ELECTRO-PLATING.

are taken out, scratch-brushed, cleaned (see Pre-
paration), and re-immersed for twenty minutes. All
the common metals are coated, but they must have
tied to them strips of zinc as before.

A great objection to the use of simple-immersion
solutions for nickeling lies in the fact that as soon
as the metal is withdrawn in part, a quantity of
acid is set free, which renders the working of the
solution nearly impossible, except with great skill.
Change is continually occurring in a solution being
robbed of its metal. For small operations it is even
better to work the last given solution with the
battery, employing a platinum anode, than to use
the zinc-contact method, because the work is done
more quickly, and the adhesion has every chance
to be better.

Solutions for Nickel Deposition by the Battery
Process.—It would appear from extensive experi-
ence that the most easily managed solutions are
those made up from a double salt of nickel and
some alkali. The double sulphate or chloride of
nickel and ammonium or potassium may be so
used with every prospect of good wTork. More than
one patent has been taken out for the commercial
working of these salts. The first appears to have
been that of Dr. Adams (1869), and very lately Mr.
Unwin, of Sheffield, has secured letters patent for
a solution of his, modified and improved from the
original mixture of Dr. Adams. The use of the
salts had been known to scientific men as early as
1855, when Mr. Gore, F.R.S., deposited the metalSOLUTIONS OF NICKEL.	155

from them, but the experiments were upon a small
scale, I understand, and only received their prac-
tically useful development at the hands of every-
day workers in the art. Particulars of the best prac-
tical methods follow.

Where cheapness is not a consideration, cyanide
of nickel dissolved in cyanide of potassium solution
affords the best liquid from which to deposit nickel,
but its working has not received much attention.
The most useful solution would appear to be that
of the double sulphate of nickel and ammonia,
dissolved in water to saturation, and then diluted
with water to reduce the density sufficiently for
working. The double salt is procurable commer-
cially at prices varying with the price of nickel
itself. Half a pound of the double salt to the
gallon will form a good solution, and f lb. will
be found even better, with less battery power.

Particulars for the manufacture of the double salt
will be found useful. Put in a deep earthenware
vessel three pints of strong nitric, acid, one part of
strong sulphuric acid, and four parts of water—
by measure. The mixture must be made slowly
and with care. To each gallon add two pounds of
grain nickel, and heat the vessel by placing in
another of boiling water; avoid the fumes, and
check any violent action by the addition of a little
cold water. When it is observed that all the nickel
is dissolved, add more until the acid is satisfied.
As soon as the solution gives over fuming, or is
found to be heavy and thick, add a fourth of its15 6	ELECTRO-PLATING.

bulk of hot water, then boil the whole, and filter
out clearly. This is a strong solution of the nickel
sulphate. Prepare next a saturated solution of
sulphate of ammonia, by dissolving in hot water—
nearly four pounds to the gallon. Allow it to cool.
To obtain the double sulphate, add the ammonia
solution to the nickel one, with constant stirring,
until the latter loses all its colour. By this time
the ammonia sulphate will have combined with the
nickel salt, and the result will be a copious precipi-
tate of the pure double salt required. Pour off
the liquid portion, and wash the salt by the
addition of more sulphate of ammonia solution
(cold).

To prepare the depositing solution, dissolve the
double salt in hot water, stirring while the water is
added until all the salt is dissolved. Then simply
dilute with water until the Twaddle hydrometer
marks nearly 70 density. Test the solution with
blue litmus-paper, and if the paper turns red, add
a little solution of ammonia sulphate, and then test
with red litmus-paper; if the colour turns to blue
add a very little sulphuric acid with much stirring.
It is somewhat important tfiat the solution should
be kept slightly alkaline, although it will work
fairly well a little either way, or quite neutral, a
condition almost impossible in practical working.
Some of these items form the subject of a patent
recently secured by Mr. Unwin, of Sheffield. The
solution is undoubtedly a good one for general
work. Some particulars of others follow, exhibit-SOLUTIONS OF NICKEL.

157

ing the fact that nickel may be deposited from a
variety of solutions.

Thus sulphate of nickel dissolved in water, with
its free acid neutralized by liquid ammonia, can be
deposited from successfully. This is Becquerel's
solution. If the liquid is worked by the zinc-con-
tact method the nickel will disappear slowly, and
to refresh the liquid it is best to stir in oxide of
nickel in sufficient quantity. If the solution is
worked by the battery current, while the anode is
properly dissolving there will be no need of fresh
metal, but the free acid must be neutralized by
adding ammonia, and it is better to have the bath
slightly alkaline than acid. Becquerel states
that the deposits from this solution are brilliantly
white.

Much has been said about the advisability of
excluding from nickel solutions the salts of potas-
sium and sodium. It is clear that such solutions
will not work well if soda is present, but the same
cannot be said of potash, as it is known that
Becquerel deposited good nickel from the double
sulphate of potassium and nickel. There can be
no doubt, also, that a very good solution might be
worked composed of cyanide of nickel in solution
of potassium cyanide. A very easily made solution,
and one from which good nickel may be obtained
by the battery process, is made by dissolving dry
crystals of protosulphate of nickel in liquid ammonia
of good quality. Place the crystals—say for three
quarts of solution—in the depositing vessel, andELECTRO-PLATING.

stir in the ammonia until the whole is dissolved.
Half a pound of nickel sulphate will be sufficient;
the liquid will be of a dark blue colour.

Another solution is made up by stirring half a
pint of liquid ammonia with a gallon of water,
then adding, with more stirring, £ lb. of nickel
sulphate, and finally adding three pints more
of liquid ammonia. This solution when used should
be heated, but not to a boiling temperature. It is
useful for the purposes of amateurs, as it works
well with a platinum anode; but nickel sulphate
must, of course, be added as the work goes on, and
if the liquid becomes acid it must be rendered
neutral or slightly alkaline by adding ammonia.

Roseleur mentions a solution which I am in-
clined to regard with distrust. It is made by
dissolving the nitrate of nickel in its own weight of
liquid ammonia, and then stirring into the liquid
as much as twenty times its volume of bisulphite of
soda in saturated solution (water). It is stated
that the deposit is of a dull grey colour. I have
not tried the mixture, but should imagine it to be
difficult to manage. Another solution of a better
kind is made by making a saturated solution of
chloride of nickel, and precipitating the metal by
stirring in, a strong solution of ferro-cyanide of
potassium (yellow prussiate of potash). Wash the
precipitate, and dissolve it by stirring into it a
solution of cyanide of potassium. It may be diluted,
but will work in the condition described. Several
solutions employing caustic potash have been tried.ANODES OF NICKEL.

159

Their distinguishing characteristic would appear to
be the ability to deposit the metal in a white and
brilliant coating, which is very liable to strip, and
apt to contain gas. Such a solution may be made
by dissolving a pound of nickel sulphate in two
gallons of water containing half a pound of tartaric
acid, and then stirring in an ounce of caustic potash.

Anodes and Anode Surfaces.—Nickel anodes are
usually made very thick, as cast from a large mass
of metal. Such plates are only suited to the
purposes of professional platers. The amateur
may work a small bulk of solution with a pla-
tinum anode, made of thin platinum foil; but in
this case the solution must be kept in metal by
adding the sulphate as it is withdrawn, and a con-
stant watch must be kept upon the state of the
solution. The plan may be good enough for
occasional plating with nickel, but is quite unsuited
for regular work. The anode surface in a nickel
bath must be larger than that of the article being
plated, and it is usual in plating factories to expose
as much as six to nine square inches per gallon.
To cast nickel into plates or ingots for making into
anodes, place the grain or cube nickel in a steel
melting-pot, add a little borax as flux, and fire
the mass as is usual with other metals. Nickel
being somewhat difficult to melt, a good plan is to
add to the mass in the pot a little grain tin, which
renders its liquefaction comparatively easy, and is
no disadvantage in the plating-vat. Anodes are
always better after working for some time. It isi6o

ELECTRO-PLATING.

difficult to obtain nickel anodes in a reasonable
state of purity. I observe that important improve-
ments are being made in the working of the metal,
which may result in the elimination of common
impurities. As now used it is very much like cast
iron, and therefore cannot be easily worked. It is
usually cast into plates nearly an inch thick, and
about twelve inches square. In the process of
casting, a pair of hooks should be fixed into one
edge for convenience of support in the liquid.
When the grain nickel, in a platinum or porcelain
basket with a platinum or carbon back, is used, a
great deal of impurity is separated in the action, so
that the lower layers are excluded from the action
altogether. Such makeshifts should be shaken up
often, and the dirt allowed to fall down. (See p. 81.)

Working the Solution.—It is important that the
articles should be well cleaned, and it is found that
nickel will deposit on well-cleaned iron and steel
as quickly as upon copper. Nickel depositing is
somewhat difficult to beginners, and the obstacles
met with are not in the choice of the solution, but
in the working of it. The solution must be kept
either neutral or slightly alkaline, otherwise it will
cause a great deal of trouble. The battery power
to employ will depend upon the scale of operations.
For large volumes of solution one cell is usually
enough, but for any volume under five gallons two
should be employed. The size of the cell should
be proportionate to the surface of the articles
exposed. For the purposes of the general amateur,NICKEL-PLATING.	l6l

with a gallon or so of solution, a pair of ordinary
quart Bunsen cells will be enough for the main
deposit, and three cells to lay the first coating.
The acids in those cells may be somewhat weak.
For larger operations two cells will be sufficient in
starting the coating, and one to finish. The factory
cell is usually composed of about eight zinc and
carbon plates, fixed to a frame after the Smee
model, and fitted so that the whole maybe dropped
into or raised from the exciting liquid to any
extent required by the work being done. The
exciting liquid is generally very dilute sulphuric
acid, and the zinc plates are, of course, amalga-
mated to prevent waste. Further particulars con-
cerning the factory arrangements as now used
follow, and of batteries more has been said under
that head.

Nickel is different from most of the metals in
electro-deposition. A great deal of power has to
be used—so much that gas must be given off
copiously in the process, particularly at the
beginning of operations. To prevent the absorp-
tion of gas by the deposit, the solution should be
strong, and as little gas as possible should be
evolved on account of this tendency. When the
work may be done very slowly, one cell only will
be sufficient, even in small operations. Nickel that
has been deposited slowly is more likely to be
tough and good, with a good surface, but too much
time must not be allowed at the commencement,
otherwise the coating may quite fail to come, or it

M162

ELECTRO-PLATING.

may be very apt to split from the surface; Thick
deposits are more difficult to lay than thin ones,
owing to their tendency to absorb gas. The articles
should be kept in motion to insure regularity of
deposit, and prevent the formation of blotches and
streaks on the surface. If the anode is so impure
as to show upon its surface a coating of blackish
matter which will not fall off as the greater part
of such impurities do, it must be brushed away in
the liquid, but not while the current is passing. It
is most convenient to stir up the solution and shake
or clean the anode every evening. A good deposit of
nickel is of a dull colour, and not of a white or
brilliant surface.

Deposits of nickel having a brilliant appearance
on leaving the solution will seldom stand. They
are very apt to strip. The proper colour is a dull
yellow, which must be worked up, after washing, by
a steel or iron scratch-brush or other usual means.
Brass scratch-brushes make nickel yellow. To
insure the deposition of a good coat of nickel, the
battery power must be uniform after the first coat-
ing is laid. The anode should be left in the
solution overnight; this will tend to keep the
bath in order. Regular and smooth deposits are
only obtained upon smooth and very clean surfaces.
There is no real difficulty in the regular and suc-
cessful deposition of nickel after the operator has
had a little practice.

When a nickel solution has been in use for some
time, it will stand in need of purification. ThisA NICKEL-PLATING ROOM.

may be done in two or three ways. I have found
the use of ammonia alum to be beneficial. Dissolve
an ounce of the alum (for each gallon of solution)
in a little hot water. Stir in this to the bath, until
a perfect admixture is obtained. Test the liquid with
red litmus-paper. If it turns the paper blue, make no
addition, but if it fails to do so, stir in a quantity of
ammonia until the desired effect is obtained, ex-
hibiting a slightly alkaline tendency. Allow any
precipitate to settle slowly, and strain or syphon
off the clear liquid, returning it to the vat when the
latter has been properly cleaned out.

A Modern Nickel-plating Room contains, as the
source of electricity, either a dynamo - electric
machine, driven by steam (see Dynamic Electricity),
or a pair of large stoneware jars as cells, con-
taining as much as ten gallons of liquid each, fitted
each with twelve zinc and carbon plates arranged
alternately in frames. The nickeling vat is a well-
bolted wooden tank, of such a size as will suit the
articles to be done, and containing, usually, sixty
gallons of the nickel solution. It is lined through-
out with best asphalt, and is nearly filled with
the solution. Around its outer edge is a raised
rail of brass, resting on which, and extending over
the solution, is a brass rod from which hang the
articles to be nickeled. Another brass rail is fixed
lower down on the inner edge, and from a rod
placed upon this is supported the nickel anode.
These two rails are joined by wire to the battery
the anode one to the carbon, and the article one to164

ELECTRO-PLATING.

the zinc. There are also a pair of vessels contain-
ing alkali cleaning solution, and acid vessel, soft
water, scratch-brush lathe, and a polishing or
buffing lathe.

With such arrangements the nickel may be de-
posited cheaply, and at a considerable profit. The
bath will give little trouble, and will work continu-
ously as long as proper attention is given to it.

Cost of Nickel Plating.—Although nickel is so
much less in price than silver, its cost as deposited
is not correspondingly less. It may with profit be
electrically deposited at ios. and over per pound.
It would appear that the Americans deposit
it more cheaply than can be competed with in
England. Table-spoons are electro-nickeled in
America at about is. a dozen, but the regular price
will probably be much higher.

Peculiarities of Nickel.—Electro-deposited nickel
is very hard, so that it is very lasting. It has a
blue tint, and takes a very brilliant polish, which,
unlike silver, it does not readily lose. It is not
affected to any great extent by the sulphuretted
hydrogen given off by burning coal gas, and is
therefore well suited for use as a covering to all
kinds of shop fittings, particularly bar pumps,
scales and weights, door plates, fire-irons, polished
fenders, carriage fittings, surgical instruments, and
innumerable other purposes. It must not, however,
be used as a lining for cooking vessels, because it
is very readily affected by acid substances. Care
must even be taken when nickeled spoons andRECOVERY OF NICKEL..	165

forks are in use—even ham fat will cause nickel to
dissolve on these, and the poisonous green salts to
appear after a few hours. Servants should be
instructed not to mistake this green substance, and
I question the wisdom of coating dessert-spoons with
it, considering the numerous acid fruit dishes now
used. I am not acquainted, however, with any cases
of actual poisoning by nickel salts through careless-
ness in the use of the metal for such purposes.

Recovery of Nickel from Old Solutions.—I am not
aware of any particulars similar to the following
having appeared in any previous work concerning
the recovery of nickel from an old solution. I give
a method which I have employed myself, and which
I have reason to believe might be improved upon.
I take advantage of the curious property of sulphate
of ammonia in precipitating the double sulphate of
nickel and ammonia from the solution. Make up
a saturated solution of ammonia sulphate in warm
water, and add to the old solution with constant
stirring. No effect will at first be observed, but in
a few minutes a deposit of the double sulphate will
begin to fall. The precipitated salt is beautifully
pure, and may be used direct in making a new
solution. The precipitation should be continued
until the liquid is colourless.CHAPTER VII.

Deposition of Gold.

Its Salts.—The useful salts of gold are its oxide,
iodide, bromide, sulphite, hyposulphite, single and
double cyanides, and terchloride, which is by far
the most generally useful for the preparation of the
others as applicable to the purposes of gold-plating.

Terchloride of Gold.—This salt is, like the nitrate
of silver, the most common, and that which results
from the ordinary dissolution of gold. The usual
acids will not dissolve gold. For this purpose
there is employed a mixture called aqua-regia—
one part of nitric acid, and three of hydrochloric
acid. To dissolve gold, for one ounce, place about
four ounces of the mixture in a suitable vessel;
place this in turn in hot water, so that the solution
within may be warmed. Use, if possible, fine gold,
as alloys are troublesome in the after-processes.
Cut the sheet into strips, and add gradually to the
mixture as it dissolves. When saturation is at-
tained to, evaporate the solution, stirring occa-
sionally until the bulk is small. Allow to cool
slowly. If too much heat is given to the mixture
while dissolution is going on, a yellow powder isSALTS OF GOLD.

apt to be formed, which must be dissolved by-
adding a drop or two extra of acid. If the gold is
pure, the resulting salt, gold chloride, will entirely
dissolve in water. If alloyed with silver a dense
chloride of that metal will form, which will probably
refuse to dissolve. This chloride is, of course,
white. If any of the yellow or brown powder
before spoken of appears now, it will not dissolve
in water, but must be separated and again dissolved
in aqua-regia, which solution must again be evapo-
rated. It will be the best, if the salt is required
for almost immediate use, to dissolve it in distilled
water, of which a small quantity only will be neces-
sary. One ounce of metallic gold will produce as
much as i oz. 164 grs. of the yellow chloride. It
will always be found less troublesome to dissolve
the fine gold.

Cyanide of Gold.-—To prepare the simple cyanide,
let the solution of chloride be diluted largely, and
the cyanide thrown down by a solution of cyanide
of potassium. The strength of this solution may
be about one ounce to the pint. It should be
added carefully, with plenty of stirring. The pre-
cipitate is a lemon-yellow powder, and is readily
soluble in cyanide of potassium. In large opera-
tions, before finishing the precipitating of cyanide,
it is best to add a little more cyanide of potassium
than at first appears to be necessary, to avoid the
risk of any of the chloride remaining in the solution.
This may redissolve a little of the cyanide, but it
may be recovered by decanting the liquid portioni68

ELECTRO-PLATING.

from the cyanide, and rendering it strongly acid
by the addition of sulphuric acid. A better way
than the above, when large quantities are to be
operated upon, is to neutralize the solution of gold
chloride by adding a little strong solution of caustic
potash or caustic soda, but this must not be used
too liberally.

Oxide of Gold.—This salt is obtained by treating
a solution of the chloride with calcined magnesia.
The precipitate is the oxide; it should be washed
with diluted nitric acid, and then with water only.
Plenty of the magnesia must be used, and if it is
desired, an excess of caustic potash or soda may be
employed in its stead, but the risk of loss is greater.
With the magnesia the heat must be regular and
not rise to boiling.

Sulphide of Gold.—This salt is generally prepared
by passing a stream of sulphuretted hydrogen gas
(see Chemicals) through a solution of the chloride
as long as any precipitate occurs. It is not often
used in electro-metallurgy. It is a dark brown
substance, in the form of powder.

Bromide of Gold.—This is seldom used. It is
usually prepared by heating the oxide in hydrobro-
mic acid, and afterwards evaporating very slowly.

Fulminate of Gold.-^K dangerous substancef It
should never be prepared until it is just wanted, as
it is violently explosive, and on this account must
not be dried, or touched while it is dry. By adding
liquid ammonia to the oxide of gold fulminate of
gold is formed. It is more conveniently preparedSIMPLE GILDING.

169

by using the chloride of gold in solution, and pre-
cipitating the fulminate from this by addition of an
ammonia salt in solution (or common liquid am-
monia). It may also be formed by adding to the
oxide solutions of ammonia, such as the chloride,
sulphate, or carbonate. This dangerous substance
is also called aurate of ammonia and ammoniuret
of gold. It is a brownish powder. After the ful-
minate is formed by ammonia, it must be washed
several times to rid it of the smell of ammonia.
The greatest care is necessary not to allow any
particles of it to dry upon the sides or edges of the
vessel. In filtering still greater care is necessary,
as particles of it are apt to dry upon the filters.
If any particles dry, they should be washed off—
not scraped—with a little cyanide of potassium
liquid.

Double Cyanide of Gold and Potassium.—This salt,
when required, may be prepared by dissolving the
simple cyanide of gold in a solution of cyanide of
potassium, and evaporating the solution almost to
dryness. The salt will crystallize out on cooling,
and only needs to be dissolved in water to form
the cyanide plating solution.

Gilding by Simple Immersion.—A solution suited
for cheap gilding, and applicable to large surfaces
generally, is made as followsDissolve 2\ lbs.
of caustic potash, 5 oz. of pearlash (carbonate
of potassium), 2 oz. of cyanide of potassium in 5
quarts of water, in which must previously have
been dissolved \ oz. of gold chloride. Before using,ELECTRO-PLATING.

this solution must be heated nearly to boiling, and
it is upon the temperature that the colour will
depend. It is suited for the gilding of clocks,
bronze figures, and gas-fittings. It may be neces-
sary to work up the surface obtained with a brush
and whiting, finishing with rouge and burnisher.

Another solution, the particulars of which are
due to M. Roseleur, is composed of pyrophos-
phate of soda 800 parts, in, 10,000 parts of water,
adding eight parts of strong hydrocyanic acid.
Convert ten parts by weight of gold into dry soluble
chloride, dissolve it in a reserved portion of the
water to which nothing has been added, and mix
both solutions together, cold. When cold the solu-
tion is yellowish, but becomes dark upon heating.
It is used hot. Poor cyanide, or hydrocyanic acid,
will make it appear red, and more must be added
until the colour disappears.

It is necessary to " quick" all the goods to be
gilded in this solution in nitrate of mercury solu-
tion in the usual way. (See Preparation.) Motion
must be given to the articles whilst being gilded.
It is recommended to gild first in a nearly ex-
hausted solution of the same kind, to lay a kind of
preparatory skin; then in a slightly richer solu-
tion, and to finish in a freshly prepared one to give
a good colour. A few seconds in each solution are
sufficient. If it is desired to lay " green" or
" white " gold, add to the last solution a solution of
nitrate of mercury, drop by drop, with stirring,
until the desired colour is apparent.SIMPLE GILDING.

171

It is not uncommon in factories to do a great
deal of the gilding by the simple-immersion process
alone. It is possible to do this by very often
" quicking" the surface in the mercury solution.
First the cleaned article is " quicked," then rapidly
gilded, quicked again and gilded, and so on for five
or six dips. The work may be got through more
rapidly than might be expected.

A very good solution for simple immersion is
made by dissolving one part of gold chloride in
water, and adding to it, gradually, thirty-one parts
of acid carbonate of potassium. Then mix the so-
lution with one composed of thirty parts of acid car-
bonate of potassium in two hundred parts of water.
The whole must be boiled for two hours. As soon as
the solution turns green, it is ready for use. It is
not necessary to " quick" the surfa^ces^f-a^jqles
to be gilded in this solution, bu^^^i; advisable tp
do so for the best work. To^&'<je|^aQrpJver oti
silver, they must be dipped^ith zint strii^oi^wire^
attached loosely to them, j? ,	^ ^ /

Silver articles are perfectly gilded b^€he^|oli6w-
ing solution, applied hot :-^Qisso^^laf^^o1ince of
each sal-ammoniac and corf^ive "sublimate in
three ounces of nitric acid, add some grain gold to
it, and boil down to half its bulk.

To gild in different colours, various methods are
in use. Thus we employ any of the solutions given,
and obtain a red gold when the temperature is
high. If a green gold is required the articles are
immersed at a lower temperature, and a solution17 2	ELECTRO-PLATING.

of silver nitrate added drop by drop, with stirring.
It is found that a very little silver in a gilding
liquid will turn the deposit green and white, while
a very little copper wall turn it red.

To gild "dead." This may be done in the simple
solutions, and is more applicable to copper and
brass than to most other metals. Make up a
mixture of sulphuric acid, 2 ounces; nitric acid,
2 ounces; common salt, \ ounce, and dip the
jewellery into it for a moment only, or until it
presents a dead appearance—then gild in the usual
way.

To "bright gild" a specific article. Let us sup-
pose that the article is a brass watch-chain. Com-
mence by pouring hot water into a vessel over
the chain, and into this scrape a quantity of bath-
brick and soap. Rub the chain. briskly in the
hands for a few minutes, to clean it. Next, sub-
stitute whiting for the bath-brick, and rub in the
hands with soap and water until all the links are
smooth. This done, wash well out in hot water
to remove the soap, and when clean, fasten a
slender wire to the article, and dip in the gilding
bath. The result is, perhaps, a fairly good colour
at first, which may remain until we think the chain
is well coated. But, as a general rule, the chain
is no sooner in the liquid than it begins to change
colour to'a dirty, and apparently unsatisfactory
yellow, wThich then deepens to brown, after which,
as a rule, no more gold will go on. This bad
colour must be worked off by rubbing in theELECTRO-GILDING.

173

hands with whiting and soapy water, when a
fine rich yellow appears; and as soon as this is
well exposed in all parts, wash off the soap. Dry
the chain in sawdust, and then bring up its surface
by rubbing briskly in the hands with dry sawdust
only. A shake will finish the process.

These simple directions will enable amateurs to
do such work for themselves, and any of the good
solutions may be employed. Articles of jewellery
which cannot be cleaned in this way should be
rubbed with a brush. For useful solutions, see
Making Solutions by the Battery Process.

Electro-Gilding.—The first necessary directions
in the art of electro-gilding are those referring to
the best solution. No solution has been found to
work so well as cyanide of gold dissolved in a
solution of potassium cyanide, or the double
cyanide of gold and potassium dissolved in water.
There are two ways by which the solution may be
piade—the chemical and the battery process. The
first is suited to the larger bulks of liquid, while
the other is well adapted to the purposes of
amateurs, or those requiring only a small quantity.

I give directions by which any quantity of the
solution may be prepared, from a pint to many
gallons.

One ounce of Gold per gallon should he present in a
good solution. This will serve as a guide for smaller
quantities, as the gallon is 160 ounces. But, as
with other metals> the proportion may vary con-
siderably. Weigh the gold, and convert it into174

ELECTRO-PLATING.

solid chloride, dissolve in water, and prepare a
solution of cyanide of potassium (i ounce to the
pint) of half the bulk. Add the cyanide to the
chloride solution with stirring. Do this slowly,
and give time to the precipitate to subside. Pre-
serve the liquid, which is to be poured off; wash
the precipitate several times with fresh water, pre-
serving these washes. Put all the washes into
one vessel, and add sulphuric acid to throw down
any stray gold. The precipitated cyanide of gold
is now to be stirred into a small bulk of a strong
solution of potassium cyanide. There should not
be enough of this to dissolve all the precipitate,
and more is added, with stirring, until the pre-
cipitate is all dissolved. It will be found even
more convenient to leave the precipitated cyanide
in its vessel after washing, and to add to it slowly,
with stirring, a solution of potassium cyanide
until it is all dissolved. But in either case the
free cyanide must be added after this is done.
The amount of free cyanide should be about one-
fourth of the whole used, and after this is added,
the solution should be diluted with distilled water
so as to give about one ounce of gold to the gallon.
If the quality of the cyanide is over 50 per cent,
the proportion given will be sufficient; but if the
quality is poor, a greater quantity will be required.

The proportions of gold and potassium cyanide
to the gallon of solution vary according to the
class, quality, or kind of work to be done in it.
A fourth of an ounce of gold will be found toSOLUTIONS OF GOLD.

}7 5

work; half an ounce will afford a better deposit in
less time ; and one ounce is sufficient for all ordinary
work. The current needed for the richer solutions
is small. Rich solutions admit of the complete
art/of electro-gilding being practised, and the
various shades of colour to be given to the articles;
while the weak solutions are only fitted for prac-
tically one colour of gilding. It is useless giving
proportions for cyanide, or the quantity of it neces-
sary to redissolve the gold salt.

It is not uncommon for lazy people to simply
add the gold chloride, without conversion into the
cyanide, to the potassium1 cyanide liquid. If the
latter is strong enough, the chloride will be con-
verted into cyanide, but the practice is decidedly
bad. If the gold chloride is used, a chloride of
potassium is formed in the liquid, and the presence
of this salt often prevents successful working, al-
though everything else may be perfect. The oxide
is not quite so objectionable, and the same may
be said of the gold fulminate. But working in
this way is expensive, and the use of the fulminate
positively dangerous.

Another solution, the advantage of which is that
it may be used cold, is also in use. Place \ oz.
of the oxide of gold in 3 quarts of water; add
1 oz. of the ferro-cyanide of potassium, and J oz.
of caustic potash. Stir, and boil the solution
twenty minutes. When cool filter off, to get rid
of the iron precipitate from the ferro-cyanide. The
solution should have a fine yellow colour. Greater176

ELECTRO-PLATING.

power of current will be required if it is used cold,
and the colour will not be so dark.

Another solution is made by dissolving 1 oz. of
chloride of gold and 10 oz. of ferro-cyanide of
potassium (yellow prussiate of potash) in 1 gallon
of water (filtered rain or distilled). -Filter the solu-
tion to rid it of the precipitated iron, and add to it
a gallon of a saturated solution of prussiate of
potash, then dilute the whole with 1 gallon of
water. If this large proportion of water is not
added, the colour of the deposit will be bad. It
will stand even more water than this, and then
give a beautiful deposit. All precautions should
be taken to get rid of the iron in the solution. It
will gild cold, but a richer colour is yielded when
the temperature is raised. If the gilding appears
to be covered with a skin of a bad colour, rub it
with a smooth brush and some acidulated water.
Brass and copper are beautifully gilded in this liquid.

Another one, based on the use of ferro-cyanide
of potassium, is made by dissolving 1 oz. of dry
chloride of gold and 10 oz. of ferro-cyanide of
potassium in a gallon of water. The iron from the
potash salt will be precipitated, and filter the solu-
tion from it. Boil the solution for an hour or two
in a porcelain or glass vessel until a precipitate
appears at the bottom. Filter again, and dilute
with 2 gals, of water. The solution, before being
diluted, should be of a fine yellow colour.

A solution in which carbonate of potash is used
is made up thus :—Dissolve 1 oz. of gold chlorideDEPOSITION OF GOLD.

177

in i\ gals, of distilled water. Then stir in, slowly,
a saturated solution of carbonate of potash ("pearl-
ash ") in distilled water until the mixture begins
to be cloudy.

Making Solutions by the Battery Process.—This
way is by far the most convenient when small
volumes of the electro-gilding liquid only are re-
quired. It is peculiarly applicable to the wants of
amateurs. Almost any of the simple-immersion
solutions may be made in this way with little
trouble. A current from two Smee or Daniell
cells is usually sufficient to dissolve in the gold.
A great advantage in this process is the certainty
that there is no loss of gold, which by carelessness
may result from many of the processes in the
chemical section.

To make a quart of gilding solution by this
means, dissolve 4 oz. of cyanide of potassium (50 per
cent.) in a quart of water kept hot by a lamp or gas,
or by being placed within another vessel of boiling
water. Connect a piece of sheet gold to the copper
of the battery, and to the zinc connect either a
platinum or gold plate. Immerse both in the
solution, and pass the current for an hour or two.
Test occasionally, to find if sufficient gold has been
dissolved in. This is done by disconnecting the
plate connected to the zinc, and substituting one of
clean German-silver for a minute. As soon as a
suitable deposit appears upon the German-silver
the solution is ready. It may be used instantly,
with the same battery power and anode, by simply

N17 8	ELECTRO-PLATING.

connecting the articles to the zinc wire. If the
colour is too dark, and the treatment with whiting
will not improve it, simply lower the temperature
until the desired shade is secured. If it is wished
to have the colour red, add a very little chloride of
copper to the solution, and if green or white gold is
wanted, add a little of the solution of silver nitrate.
In such work it is not of much consequence how
much gold may be dissolved in the solution if the
deposits obtained are good. A large percentage
of gold will work faster than a weak solution, and
the work will probabl/ be done too fast for con-
venience. In large operations, however, it is well
to weigh the anode before and after the opera-
tion, so that the gold may not be allowed to exceed
i oz. per gallon—unless for especially rapid work.
In simple-immersion solutions a low percentage of
gold will give a thicker deposit than a solution
rich in metal. But in all simple-immersion solu-
tions the deposit is of the most superficial cha-
racter.

In the^ preparation of such solutions as the above,
the anode should be suspended by gold wires
covered with strong varnish, or, which is better, a
support of platinum wire, which will not be dis-
solved by the liquid. If the anode is large enough
to allow its end to lie above the surface, such sup-
ports will be unnecessary, but care must be taken
to shift the anode occasionally up and down, because
it is liable to be corroded and cut through at the
surface of the liquid. In such solutions the processCOLD-GILDING SOLUTIONS.	179

of gilding is rapid and simple. Care must be taken
to keep the solution at about the same specific
gravity—that is, to prevent its becoming too dense,
by adding water every evening, to make up for that
evaporated off in the process. With simple-im-
mersion solutions care must be taken to both add
water and gold—chloride in solution will generally
be found to fulfil both conditions.

Cold-Gilding Solutions .—Most of the foregoing
solutions are used hot, and are suited to the better
class of work. But a great deal of gilding is done
on a large scale in cold solutions. It is usual, how-
ever, to deposit a mere film of copper upon the
goods just before gilding, both to insure good con-
tact, and to improve or darken the colour of the
gold deposit. The articles usually treated are
large, such as clock cases, " fine " goods in fenders
and fire-irons, bronzes, and large chandeliers.
Having fixed upon the volume of liquid likely to
be required, it is well to make up nearly twice as
much, because such solutions work much better in
large volumes than in small quantities.

Dissolve 2 lbs. cyanide of potassium (50 per cent.)
in 4 gals, of water. Dissolve 5 oz. of solid gol.d
chloride in 1 gal. of water. Mix the solutions, and
filter if any sediment is seen. Boil the liquid for
fifteen minutes before using. When it gets ex-
hausted, add solid chloride of gold and a little
cyanide of potassium in water. But the directions
applicable to other solutions may be made use of
in working this. It will, however, be unnecessary180	ELECTRO-PLATING.

to allow a daily addition of water, the evaporation
being so insignificant.

Another cold-gilding solution is made thus :—
Dissolve 2 lbs. of cyanide of potassium (50 per
cent.) in 5 gals, of water. Convert 4 oz. of gold
into the solid chloride, dissolve it in water,
and stir in 2 quarts of liquid ammonia. The
usual precipitate of fulminate of gold will be
thrown down. Wash the fulminate by filtration,
using every precaution not to use any hard sub-
stance or article to remove it from filters or vessels.
Wash the fulminate into the vessel in which it is
intended the solution is to be, and add the potassium
cyanide solution. The fulminate of gold will dis-
solve quickly, and when completely invisible stir
the liquid, and boil for nearly an hour to get rid of
the excess of ammonia. To refresh this solution in
gold, the chloride must be converted into the ful-
minate. Dissolve this with a solution of potassium
cyanide, and add the liquid occasionally, little by
little, as it is required—too much care cannot be
exercised in the use of this highly explosive sub-
stance. So long as it is kept wet, and quite free
from violent friction, it is safe enough.

The colour of the deposit from both these solu-
tions will serve as a guide to the quantity of gold
necessary. If the colour is too pale, a little more
gold will probably darken it. But a stronger
current will often do the same, so that adding to
the current should be tried before adding gold. If
there is too much gold, and the current strong, theCOLOUR OF THE GOLD.	l8l

deposit will be too dark; it may be red, or even
brown. Too much cyanide of potassium will cause
the work to go on very slowly, and the colour will
be very poor, because an excess of cyanide will
dissolve off the gold as fast as it goes on. If the
bottom of the article receives a good deposit, and
the top a poor one, it indicates that there is a slight
excess of cyanide, but that the fault may be reme-
died by stirring, and keeping the articles in motion.
A stronger current will generally counteract the
effects of too much cyanide, but the addition of
gold may be necessary—chloride to the first and
fulminate to the latter solution.

" Colour " in Electro-Gilding.—It is of the greatest
importance to possess a knowledge of the art of
regulating the current and general working of hot
electro-gilding liquids, so as to make the process
useful in producing not only deposits of gold, but
those of any desired colour.

As a general rule, it will be found best to obtain
any excessive colour by additions to the bath, and
not by attempting to work it up to this by the
current or temperature. Thus, to obtain red or
green gold of decided colour, it will be necessary
to make additions in the shape of acetate of copper
and nitrate of silver. Now, if it is not required to
perpetually gild in this colour, or at least until all
the added metal is worked off, the bath will be
spoilt. It is always wiser, when excessive colour
is required, to either make up a separate solution
for that particular colour, or to make the main182

ELECTRO-PLATING.

bath up if the work is always to be carried
on.

To make up a bath for red gilding, grind a little
of the acetate of copper (crystallized) to powder,
dissolve in water, and add to the bath, with stirring,
every evening as much as may be required. In a
new bath, where there will be no troublesome sedi-
ment to disturb, the addition may be made at any
time, and the quantity augmented if the colour is
not sufficiently deep. It must not be forgotten,
however, that gold so coloured is not so fine as a
yellow gold. Attention should be given to some of
the directions which follow, so that the battery
power and temperature may be regulated to assist
in the production of deep colour, it being important
that too many of the foreign substances are avoided
in a good bath.

To obtain green and white gildings the addition is
a solution of the crystallized nitrate of silver. This
is added in the same way as the copper. A very
little (a few drops) will generally produce green
gliding, and a little more white.

To deposit a gold of pink appearance is a more
troublesome matter. The surface is first coated
yellow, then thinly red, and over this is produced
an exceedingly thin coat of silver in a silvering
solution. Such surfaces are very lasting, and
ought to be burnished.

A good cyanide-gilding solution should be of
sufficient strength to allow of its producing from a
pale and poor-looking deposit to a deep andCOLOUR OF THE GOLD.

nearly red rich gold. For such purposes the solu-
tion may even contain as much as i \ oz. of gold
per gallon, but over this it is not advisable to go,
for the reason that the paler tints are not readily
obtainable. The poorer solutions will produce fairly
pleasing tints when the current is strong and the
temperature high, but the darker shades are very
apt to have a dingy appearance, instead of that
mellow and clear surface which is the chief aim of
the practised gilder.

A dead gilding will be produced by the addition
of a little of the fulminate of gold in solution to
the bath immediately before gilding, or dip the
articles (brass and copper) before gilding in a
mixture of sulphuric and nitric acids.

Speaking of the solution recommended by me,
as holding i oz. of gold per gallon, it will pro-
duce its darkest effect when the temperature is at
boiling point, the battery power two cells of the
Smee or Daniell type, and the anode only a few
inches from the articles. Almost any desired shade
may be obtained by lowering the temperature, the
battery power, and keeping the anode and articles
further apart. The colour will, as a general rule,
be too dark on removal from the solution, but the
process of scratch-brushing will clear off the super-
ficial covering and expose a pleasing effect. It is
necessary to producer darker gilding than is finally
required. If there is a difficulty in obtaining a gold
of yellow tint, the addition of some caustic soda in
solution will produce it, but of this salt very littleELECTRO-PLATING.

must be used, and then only when absolutely-
required. A great deal may be done by allowing
more or less anode to dip into the solution. If a
solution is poor in metal, and it is required to
bring it up to i oz. per gallon, let the anode
be much larger than the articles, and the deposition,
with adding of gold, will go on at once. If the solu-
tion is too rich to produce, with any working of
current, anode, or temperature, the gold required,
its fault may easily be corrected by allowing less
anode surface than the articles expose until the
desired effect is produced. These changes will be
found to work best when the free cyanide is above
one-fourth of the whole in solution. If there is a
greater percentage of free cyanide, less anode sur-
face will be found to work the solution, and if a less
quantity is present, a larger anode will be neces-
sary, and it must be nearer to the articles, or a
strong current must be used.

If the colour of articles after being gilt is acci-
dentally bad, it may generally be improved by
treating with alum, one part; sulphate of zinc, one
part; common salt, one part; and saltpetre, two
parts. This is to be made into a paste with water,
smeared over the articles, and the latter then
heated upon an iron plate and thrown into water.
The surface is then to be scratch-brushed or other-
wise cleaned to bring up the surface. This cannot
be done with articles which are soft-soldered to-
gether. Jewellers generally remedy a bad colour
by applying a paste of borax and water, heatingANODES OF GOLD.	185

very highly, and plunging suddenly in water
strongly acidulated with sulphuric acid. But it
will generally be found better, if it can be afforded,
to regild the articles under different conditions of
bath and current.

Bearing upon the colour of gilding is a practice
which is carried on in plating factories by which
copper and silver are dissolved into the solution
from anodes of these metals. But it must be dis-
tinctly understood that solutions so treated are
always kept for such special purposes as render
the introduction of foreign metals necessary.
Common plating solutions would be spoilt by the
treatment. It is not uncommon, for instance, to
work a gilding solution with a copper anode until
a rather red deposit is obtained, when it is replaced
by a gold one of small surface. The temperature
in such cases ought to be high, and the battery
power as much as two cells, as before directed.
When a green gold is required as a standard
colour, work with an anode alloyed with silver.
The green in all gold colour is produced by silver,
and the red of English gold coins by an admixture
of copper.

Anodes.—It is of the highest importance in all
common gilding in cyanide solutions to employ a
gold anode only. The object is, of course, to dis-
solve gold into the solution as fast as it is with-
drawn. Anodes should be sheets of gold for
common work, and they should present as near as
possible a surface as great as that being gilt. IfELECTRO-PLATING.

less surface must be exposed, it may to a certain
extent be compensated for by stronger current, or
by having the anode and articles nearer together.
For special work, such as the gilding of wires,
which are required to be drawn through the liquid
regularly, gold strip or wire may be employed as
anode surface. The anodes should be of pure gold,
especially in the best class of work. A solution is
often spoilt by working it with impure anodes. If
the anodes are not sufficiently large to have part
of their surface above the liquid, they must be hung
therein by platinum hooks, or gold wires protected
by gutta-percha tubing, or coated with some heat-
resisting varnish—otherwise they will be dissolved
off and severed at the surface of the liquid,
where the free cyanide is present in greatest
quantity.

Distance to be Maintained.—It is impossible to
give useful figures, so much do the necessary sepa-
rations vary with the current and solution. The
distance is readily ascertained. When the solution
is good, temperature high, and current strong, 9
inches may not be too much; if the deposit looks
pale at that, decrease the distance.#

Time Necessary in Electro-Gilding.—Two or three
minutes will usually fee sufficient to deposit a very
good coating. This also will depend upon the
various conditions. The work is usually done too
fast. It should be, remembered, moreover, that a
very little gold will properly protect a large sur-
face, and that the better covering properties ofGILDING INFERIOR WORK.	187

•

gold will render unnecessary the laying of such
thicknesses as are produced in silver-plating.

Inferior Work, such as the plating of zinc or tin,
should always be kept out of the standard bath
until these metals have received a deposit of
copper in a cyanide of copper solution. (See De-
position of Copper.)

Steel and Iron may be gilt in a solution slightly
weaker than the standard one. Very little free
cyanide of potassium should be present. A weak
current will be sufficient.

German-silver should be gilt in a solution having
very little free cyanide. "Quicking" should be
employed wherever possible before gilding all
articles except silver and well-cleaned copper; it
insures a good connection between the gilding
and the real surface. (See Preparation.) Vessels
which require only the inside to be gilt, such as
cream-jugs, are filled with the gilding solution,
with an anode of gold hung in the middle, the
other wire from the battery being connected to the
vessel itself. When the liquid cannot be held so
high in the vessel as to gild its upper edges and
the lip, a pad of cotton, thoroughly wetted with the
solution and dipping in it, should be led up to the
point. If this fails, the anode should be placed
upon the pad and the current passed as usual. It
is, perhaps, a better way to protect the adjacent
parts with a varnish, and to gild in the usual way
in the bath.

Free Cyanide in the Solution.—This varies from188	ELECTRO-PLATING.

causes before mentioned. If the colour of the
deposit is " foxy," too much free cyanide may be
suspected. If, however, the colour is pale and
weak, and the usual battery power used, too little
free cyanide may be suspected. If the anode is
dirty, and shows little sign of having been dis-
solved from, too little cyanide is present. If the
anode is very pale, and gas appears to rise from it,
too much free cyanide is probably present. The
remedy for too little is to supply more, and for too
much the solution may be worked with too large
an anode, which will give metal to take the excess
up, or a little chloride of gold and water maybe
added to the liquid. (See Cyanide, under Chemicals.)

Battery Power required.—As a general rule, em-
ploy one cell of the Smee or Daniell type, and let
its plates be as large as the anodes used in the
plating solution. In special cases, which have
been indicated before, two cells may be necessary.

Care of Electro-Gilding Solutions.—It is very
important that when the plater obtains a good
solution he should exert himself to keep it so.
Contamination direct with such metals as Bri-
tannia metal, tin, lead, or zinc, should particularly
be avoided.

The Recolouring of Gilt Work.—I am induced to
insert here some particulars relating to the re-
covery of colour in gilded watch-chains, ear-rings,
and other jewellery of small bulk. Two or three
methods are given in some other books which in-
volve the violent heating of the article, and myRECOLOURING.	189

own direct experience has been that such treat-
ment is ruin to a thin coating* although it works
on good gold-plating. I treated some gilt chains
by the composition and method given by myself
(p. 184) with regard to improving a bad colour, and
found the thinner ones spoilt, rendering necessary
the overdoing of the gilding.

What is given here may be used for bad colour
when it is too pale, but it is more generally appli-
cable to ordinary gold chains—not gilded work,
although it may be used for both. The first thing
to be done is dipping in dilute nitric acid, then in
strong nitric acid for an instant only, then in water
just before treating as hereafter directed. To pro-
duce a

Red Gold, mix together equal parts of copper
sulphate, sal-ammoniac, borax, and common alum.
Powder "together, and moisten with water. This
and all the other compositions here given are to be
placed in a plumbago crucible when required for
use. A little water is to be added, and the com-
position must be made to boil by gentle heat. Tie
a horsehair to the work to suspend it with, and dip
into the mixture immediately after cleaning, leav-
ing it in for several minutes. Take out, and rinse
in a pan of boiling water. At this stage the work
should look black, or nearly so; dip in the crucible
again until the work is of the desired colour—ex-
cept for scratch-brushing. Finish by rubbing in
the hands with whiting—if a chain—or by scratch-
brushing.190	ELECTRO-PLATING.

For Yellow Goldy use a well-pounded mixture of
saltpetre, 6 parts; copperas, 2 ; white vitriol, 1 ;
alum, 1.

For Green Gold, a well-mixed composition of
saltpetre, 5 parts ; sal-ammoniac, 5 ; Roman aloes,
6; verdigris, 5.

In no case is it safe to subject any valuable
article to experiments to improve its colour if they
involve strong heating or plunging in strong acids.
Care should always be taken by the experimenter
to note whether the article is soft or hard-soldered.
Soft-soldered articles should not, for safety, be
heated above the point of boiling water, and greater
care generally should be taken with them.

It is not usual to keep gold-plating solutions in
the kind of vats used for silver. It is usual to gild
in an iron-enamelled tank or pot, and small opera-
tions may with every satisfaction be carried on in
any convenient glass or porcelain jar or basin of
sufficient depth. It is usual in small operations to
place the vessel, glue-pot fashion, in another con-
taining water as hot as may be required. Larger
vessels of iron are heated direct by gas, lamp, or
stove. A constant motion should be given to the
articles while gilding. Small articles should be
hung together upon a wire, or placed in a platinum
basket and kept shaking about in the solution.
If the anodes are not pure, but contain silver, they
will slowly but surely spoil the solution, which at
length will fail to give any but poor and pale, or
green, deposits. For this reason the anodes shouldRECOVERY OF GOLD.	191

be quite pure, to keep the solution in good order.
Water should be added every evening to make up
for that lost by evaporation, and with this water
should be given a little of the potassium cyanide,
to make up for that converted into carbonate of
potassium by exposure to the air. Liquids con-
taining free cyanide are constantly absorbing car-
bonic acid from the air to make the useless car-
bonate of potash. Dust should be kept out of the
solutions, and every evening, or when the work is
done, the whole should be well stirred—the stronger
the solution the greater the necessity for this pre-
caution.

Recovery of Gold from Spoilt Solutions, Residues,
or Washes.—When, by accident or constant working
for a long time, a gilding solution becomes deterio-
rated in working value, it may become necessary
to recover the gold from it and make a fresh
solution.

The operation for cyanide solutions must be per-
formed for safety in the open air, or where there is
a good draught. The best way is to precipitate as
much as possible ofthegold by adding hydrochloric
acid, with stirring, then heating nearly to boiling.
Allow to cool, pour the liquid portion off, and dry
the precipitate, fusing it afterwards with its weight
of litharge to get rid of contaminating base metals.
The remainder of the solution will probably contain
some gold, which may be thrown down by a few
scraps of zinc.—The dry way is to evaporate off all
the solution by boiling, and drying the residue,192	ELECTRO-PLATING.

fusing as before to obtain the gold. After the
fusing, in both cases, it is best to get rid of the
lead and other rubbish by placing the fused mass
in nitric acid. The greatest care is necessary in
all such cases—fusing and precipitating-^to avoid
the cyanogen gas given off. The button of gold
obtained by fusing may be rolled or hammered out
to thin sheet to form the new gold.chloride.

Waters that have been used in the various opera-
tions of making a solution by the chemical process
should be preserved, and if there is any gold in
them it may be recovered by hanging in them
scraps of zinc, adding a very little sulphuric acid.
In a day or two every vestige of gold will be
thrown down.

Analysis of Gold-plating Solutions.—To ascertain
the quality at any time of a gilding solution, many
methods are adopted by the consulting chemists to
whom such work is usually intrusted. There is no
necessity that the work should go beyond the
plating-room, or from the hands of the plater. I
here give a method which is recommended to
platers in general, the results being certain.

A quantity of the solution is measured and
placed in a porcelain crucible, and slowly evapo-
rated. When the remainder assumes a thick appear-
ance, add a few grammes of litharge, and evaporate
to dryness. Cover the crucible, and raise it to a
red heat for about five minutes. Allow to cool,
and place the fused mass in warm nitric acid to
dissolve out the lead.DEPOSITION OF GOLD,

193

. Cost of Gold Plating.—Gold may be deposited in
the large way, including all working expenses,
interest upon capital and losses, at about 5s.
an ounce. This will vary very considerably in
different shops. Gold needs less battery power
and time than silver, but an ounce of it covers a
much larger surface. Gold-plating, metal in-
cluded, will be at least six times as expensive as
silver-plating, even although the deposit should be
as thin as that usually given by simple-immersion
solutions. Such articles as watch cases may be
properly gold-plated at a cost of about 5s.

OCHAPTER VIII.

Deposition of Aluminium.

Its Manufacture from Bauxite.—Aluminium
would form a plating of the greatest value in arts
and manufactures were it practicable to deposit it
like silver or nickel. For many years electro-
platers have expected that something would be
done with it by those who devote their time to
original investigation—true scientific men. In-
formation is, therefore, eagerly sought for. I
attach to my remarks upon what has been done
by others some results obtained by myself in this
direction—not that I wish them to be accepted as
solving the problem, but as a slight advance upon
what had previously been done.

At Salindres, near Alais, is situated a small
factory for the production of aluminium. Bauxite
is heated with soda in an ordinary reverberatory
furnace. The result is aluminate of soda, which is
formed into balls, with an admixture of salt and
coal, and heated to a white heat in vertical retorts
into which chlorine gas is introduced. A double
chloride of soda and alumina distils over, whichDEPOSITION OF ALUMINIUM.	195

is fused with the addition of 35 per cent, of sodium,
and 40 per cent, of cryalite as a flux. The metal
which gathers at the bottom of the crucible is
poured into moulds, and is ready for the market.
Its production would appear to cost 80 f. per kig,
(2*6803 lbs. troy), while it is said that the metal is pro-
curable at 100 f. per kig. However this may be, it is
certain that the metal costs a great deal more in Eng-
land, where as much as 10s. per ounce is frequently
asked for the sheet and wire. The chloride is pro-
curable at 9d. per ounce, and cheaper for large quan-
tities. Should a large demand arise, the price of
aluminium would undoubtedly be very much lower.

A great many of the researches of Bunsen, Sainte-
Claire Deville, Duvivier, and others, are in print,
but they have little practical value, except as
indications that aluminium is exceedingly diffi-
cult to deposit as a reguline film.

The patents of Thomas and Tilley were for pro-
cesses of no value as far as the deposition of
aluminium was concerned, although it was claimed
that the metal might be deposited from a solution
composed of freshly precipitated alumina dissolved
in boiling water containing cyanide of potassium ;
and also from a solution of calcined alum in
solution of potassium cyanide. The result is not a
deposit of aluminium, but the liberation of hydrogen.

It is also stated that aluminium is deposited
from " certain preparations " at a temperature of
500° Fahr., but no particulars are to be had, which
renders such statements worse than useless. (See196

ELECTRO-PLATING.

Chemical News, vol. xxiv. p. 194.) Sprague elec-
trolyzed the solutions spoken of as patented by
Thomas and Tilley, and his observation is that
" they do decompose, only, unfortunately, they do
not deposit aluminium, but simply give off hydro-
gen"—this is with six Bunsen cells. He further
states his inability to deposit the metal from any of
the solutions.

Mr. A. Bertrand gives some particulars of a
process by which aluminium may be deposited,
from the solution of a double chloride of aluminium
and ammonium. It is stated that a clear white
deposit is given to a plate of copper, and that it is
capable of receiving a very high polish. I have
tried the same solution, with more or less salt, and
battery power from one Daniell to ten Bunsens,
and the best X can obtain is a highly granular and
useless deposit, the half of which is not aluminium
—gas is given off in abundance, and the process is
very wasteful. The deposit is improved by concen-
trating the solution, and keeping it at a boiling tem-
perature during the operation. The process would
appear to be worth experimenting further upon.

I obtained white deposits of aluminium from its
sulphate in saturated solution, concentrated and
acidulated with a little sulphuric acid. The tem-
perature may be 150° Fahr., or over. The battery
power was from two to six Bunsens. It should be
remarked that, through some unaccountable defect,
the deposit is by no means a certain result of elec-
trolyzing the solution- It would appear that muchDEPOSITION OF BRASS.

197

power is needed to decompose this solution quickly-
enough to deposit aluminium. Other salts may be
used as well as the sulphate. In all cases the
anode should be aluminium, and the battery not
less than four Bunsen cells. In some cases a dirty
deposit takes place, with no appearance of alu-
minium in any other condition, and in others there
appeared under the slimy deposit a thin white
coating of the metal, which had good adhesion.

It has been suggested that aluminium might be
easily deposited with other metals, such as silver
and nickel.

Deposition of Brass.

This process is called brassing. It means the
coating of metals with an alloy of copper and zinc.

Solutions for Brassing.—Various solutions are in
use and have been patented. They all need a
current of great strength to decompose them com-
pletely. A good solution, used by De Salzede, is
made as follows :—Take 25 gals, of water; dissolve
a pound of cyanide of potassium (50 per cent.) in a
gallon of it; then add 50 lbs. of potassium car-
bonate, 4 lbs. of sulphate of zinc, and 2 of chloride
of copper, to the larger bulk of liquid. Now heat
the solution, but not to boiling, until the salts are
dissolved, and then stir, adding 25 lbs. of nitrate of
ammonium. Allow the liquid to settle for twenty-
four hours, and then stir in the cyanide of potassium
solution. Allow again to settle, and then draw off
the clear portion, which is ready for use. A largeELECTRO-PLATING.

anode of brass must be used, and a powerful cur-
rent is necessary. Two anodes may likewise be
used, one of zinc, and another of copper.

Another solution is made by dissolving 2\ lbs.
of American potash in 6 gals, of hot water, and
filtering the solution. Also dissplve ozs. of
acetate of copper in half a pint of strong liquid
ammonia, and stir it into the first liquid. Then
add 5 oz. of sulphate of zinc, stirring until dissolved,
and finally add 2 oz. of potassium cyanide. Filter
the solution, and when working raise its tempera-
ture to ioo° Fahr. The anode must be of brass,
and the current strong.

Another:—Dissolve 10 lbs. of acetate of potas-
sium, the same of acetate of copper, 1 of acetate
of zinc, in 5 gals, of hot water. Prepare a strong
solution of cyanide of potassium, stir it into the
liquid as long as it precipitates and redissolves the
mixture. When all the precipitate has dissolved,
add about < one-tenth more of cyanide solution to
form free cyanide. The anode must be brass. Mr.
Wood gives the composition of a good solution
Dissolve 1 lb. of potassium cyanide, 2 oz. of
cyanide of copper, and 1 of cyanide of zinc, in
1 gallon of distilled water, and add 2 oz. of sal-
ammoniac. The working temperature is 150° Fahr.,
the anode brass and the battery power about six
Grove's or Bunsen cells. Mr. Watt's formula is as
follows :—Acetate of copper five parts, cyanide of
potassium eight, sulphate of zinc ten, liquid am-
monia forty, and caustic potash seventy-two parts.DEPOSITION OF BRASS.

199

Reduce the copper salt to powder, and dissolve it
in eighty parts of water, then add twenty of the
liquid ammonia. Dissolve the zinc salt in 160
parts of water, at 180° Fahr., and add the remaining
twenty of ammonia to it, and stir the mixture
strongly. Dissolve the potash in 160 parts of
water, and the cyanide in 160 of hot water. Add
the solution of copper to that of zinc, then add the
caustic potash, and then the cyanide. Dilute the
mixture to 8 gals, by adding water, and thoroughly
stir the solution. Use a strong battery, add a little
ammonia occasionally, and when it works slowly
add cyanide of potassium in solution.

A good solution may be made by dissolving, in
1,000 parts of water, twenty-five of copper sulphate,
or twelve and a half of copper acetate, and fifteen of
fused chloride of zinc. Precipitate the mixture by
a solution of 100 parts of carbonate of sodium, and
stir the solution. Pour off, and wash the precipi-
tate several times, allowing it to settle each time.
Add to the precipitate a solution of fifty parts ot
bisulphite of sodium, and 100 of carbonate of
sodium dissolved in 1,000 of water, and whilst stir-
ring with a wooden rod, add a strong solution of
potassium cyanide until the precipitate is just all
dissolved, then add three parts more as free
cyanide. This is worked by a brass anode, and a
current from about six Bunsen cells.

Working Brassing Solutions.—It will be unneces-
sary to give further examples. Good brass may
be deposited from most of the mixtures. Those200

ELECTRO-PLATING.

with the largest percentage of zinc yield, with a
full current, the poorest brass, and of a pale colour.
The same solutions may, however, be made to give
a deeper-coloured metal by using less battery
power. It is an easy matter to regulate to a nicety
the proportions of zinc and copper in a solution.
If the mixture contains too much zinc, use a copper
anode only until the brass begins to look too red,
when the usual brass anode may be replaced. If
too much copper, and working wTith a full current,
employ an anode of zinc only until the deposit
begins to look poor and pale. If the current is too
strong, the solution will yield too large a propor-
tion of zinc, and the work will look whitish. But
this will depend greatly upon the proportions of
zinc and copper in solution. If the deposit is too
pale, and the solution with battery power about
right, give motion to the articles, which will cause
the colour to deepen considerably.

It would appear that those solutions containing
ammonia are really the least troublesome, because
they dissolve the zinc from the anode with greater
freedom than the others. In these solutions the
want of ammonia is indicated by there being a
white surface of zinc upon the anode. The plate
should look like brass while working, or a little
paler. Too much ammonia will make it red or
dirty. Anodes should be yellow brass of good
quality, or gun metal will work with slightly less
battery power. The surface must be greater than
that being coated. By employing a current of goodBATTERIES FOR BRASSING.	201

strength, no difficulty need be experienced in work-
ing these brassing mixtures. They may be kept in
order by dissolving more or less of the metal into
them by anodes. When this is done along with the
other work greater battery power is needed.

Batteries for Brassing.—The currents necessary
for working a large bath are so great, that it is
doubtful economy to employ the galvanic generator
at all. When as many as ten gallon Bunsens are
needed in series for the larger operations, and
coating of very large work, the expense of nitric
acid and zinc, along with the cost of maintenance,
would appear to point to the wisdom of using only
dynamo-electric machines driven by steam. The
first cost would, of course, be much greater, but a
remarkable saving would at once be instituted.
For baths containing as much as 100 gallons of
solution, the battery will frequently need to be as
strong as eight or ten Bunsens or Groves. For
smaller vats from three to six cells will generally
be found enough, but there should be no difficulty
in fixing the necessary strength of current for a
given surface of anode. The battery plates need
not be quite as large as the anode. By a careful
system of varying the current, any quality of brass
may with the greatest facility be deposited upon
the common metals. The ordinary asphaltum vats
are in use. Those lined with best Portland cement
are probably better, and enamelled iron tanks the
best. Wooden tanks are, however, very useful.
They must be carefully jointed and bolted.202

ELECTRO-PLATING.

To Preserve the Colour of the Deposits, let the
articles be well washed in water, then in water to
which some caustic lime has been added, and finally-
dry in a stove or hot sawdust.

Deposition of Platinum.

Chloride of Platinum is the most common salt,
and from this most of the tried solutions have been
made. Its price in small quantities is about 24s.
per ounce. It is most economically made by dis-
solving platinum scraps in a mixture of one part
nitric acid and two and a half of hydrochloric acid.
The mixture must be kept hot, but must not be
made to boil. As soon as dissolution is complete,
evaporate the mixture slowly, and when nearly-
dry set aside to cool and crystallize. If the heat
has been too great, the salt will be of an olive
colour instead of a full rich yellow. It will be
nearly red if iridium is present. It is usual to
make all the other salts of platinum from this. It
should be crystallized if it is to be kept.

Sodio-Platinic Chloride is obtainable commer-
cially at about 24s. per ounce. It is usually pre-
pared by adding common salt to a solution of the
platinic chloride. It is a yellow salt.

Simple-Immersion Deposition of Platinum.—To
obtain a reguline white deposit of platinum is no
easy matter. The simple-immersion process may be
useful for platinising such things as Smee battery
plates, Bunsen carbons, and 50 on; but there isDEPOSITION OF PLATINUM.	203

very little certainty in obtaining good metal by the
simple-immersion process. The deposits required
upon Smee plates and carbons are highly granular,
and are very often black. A solution which may be
used for depositing platinum by simple immersion
on small articles is made thus :—Dissolve chloride
of platinum in water to saturation; add to this
carbonate of soda, powdered finely, until the mix-
ture effervesces and ceases to effervesce. Then stir
in a little glucose, and finally add as much common
salt as will produce a white precipitate. The
articles must be immersed in a basket of zinc wire,
or any vessel of zinc well perforated. A few
seconds are usually enough to produce a deposit.
If everything is not right the plating will be of a
bad colour, or black. Use hot.

To platinise Smee plates or carbons, prepare a
vessel of dilute sulphuric acid 20 per cent. Tie to
the plate a slip of zinc, and place the latter in a
porous pot filled with liquid within the outer vessel,
and let the plate occupy the latter. Drop in a little
strong solution of platinic chloride, and stir. # As
soon as a good coating is seen to form, strengthen
the solution by adding a little more platinic chloride.
On removal dip in water, and dry spontaneously.

Platinum Solution for Battery Process.—Prepare
a solution of the sodio-chloride of platinum, stir in
a little oxalic acid, and then enough caustic soda to
make the mixture alkaline. This is not the easiest
solution to work. Another, recommended by
Roseleur, is made by dissolving twelve parts of204	Electro-plating.

dry chloride in 500 parts of water, and filtering;
dissolve also 100 parts of crystalline phosphate of
ammonia in 500 parts of distilled water, and stir it
into the platinum solution. This addition will pro-
duce a large amount of precipitate. Add to the
mixture at once a previously prepared solution of
500 parts of phosphate of soda in 1,000 parts of
distilled water, well stir, and boil the solution until
there is no odour of ammonia, and its alkaline con-
stituent is neutralized, which will be indicated by
the liquid reddening blue litmus-paper. , It becomes
colourless, and is ready for use—hot. A current
from three or four Bunsens will be necessary to
work it. The anode should be platinum, but it
will not, as in most other solutions, dissolve to
make up for loss of metal, so that it is necessary to
occasionally refresh the mixture with some chloride
of platinum. As yet, no really successful solution
for the electro-deposition of platinum has been
devised—platinum appears to be too difficultly
soluble, and, unlike gold, will not dissolve in
cyanide of potassium.

Deposition of German Silver.

German-silver is usually an alloy of copper, zinc,
and nickel, which form a very good quality of the
metal.

Depositing Solution.—Dissolve good German-
silver in nitric acid. Prepare a solution of cyanide
of potassium, and stir into the German-silver mix-DEPOSITION OF GERMAN SILVER. 205

ture slowly, until the whale of the metal is pre-
cipitated. Then pour off the exhausted liquid,
wash the precipitate, and stir into it a strong solu-
tion of cyanide of potassium until it is quite dis-
solved ; then a very little more cyanide, and dilute
the mixture with twice its bulk of water.

Another solution may be used. Dissolve a pound
of each cyanide of potassium and carbonate of am-
monium in a gallon of water. Heat the mixture to
1600 Fahr., and dissolve German-silver into it by
means of an anode of German-silver and a receiv-
ing plate of brass or copper. Pass a powerful
current, such as that from six or eight Bunsens,
until a good deal of metal is dissolved in—a bright
cathode plate should be introduced occasionally as
a test, and when it receives a good deposit the
solution is ready to work with a strong current.
Its constitution may be varied by adding copper
or zinc from copper or zinc anodes. If the deposit
is too red, stir in some carbonate of ammonia; if too
white, the want of cyanide is indicated.

All solutions made from alloys of this kind require
strong currents to decompose them effectually.

Simple-Immersion Nickel Alloy.—I add here a
method of plating published in the scientific jour-
nals some time ago. Not having tried it myself,
I am unable to speak with confidence of the results,
but should imagine them to be agreeable to the
description.

The alloy is one resembling German-silver, and
it is said that the coating is more durable than one206

ELECTRO-PLATING.

of silver. First melt one part of copper and five of
pure tin—preferably Australian tin. The alloy is
granulated as usual, but not too finely, and then
mixed with water and cream of tartar—as free from
lime as possible—into a paste. To each 200 parts
of the granulated alloy is added 1 part of oxide of
nickel, and the articles to be plated are laid in it.
After boiling for a short time they become " beau-
tifully plated." Some fresh oxide of nickel must, of
course, be added from time to time.

It is said that the brass and copper articles require
little or no previous preparation. Articles of iron
will not coat in it; they must, therefore, be coatetf
in the usual way, with copper first—in the cyanide
of copper solution, or, cheaper, by the simple-im-
mersion processes before spoken of. (See Deposition
of Copper.) By adding some carbonate of nickel to
the nickel bath, or to a common tin bath, and boil-
ing, a coating richer in nickel is obtained, and
darker, varying in colour from that of platinum to
a blue black, according to the amount of nickel salt
added.

Deposition of Zinc.

It does not pay now to deposit zinc by electricity.
The so-called process of "galvanizing " has nothing
to do with electricity. It is simply a coating of zinc
obtained by immersing the previously cleaned iron
articles in a bath of melted zinc—rthis is better
than the galvanic process as a protection, but it is
more detrimental to the quality of the iron treated.DEPOSITION OF TIN.	20J

To Deposit Zinc.—Make up a solution by dis-
solving 2 oz. of zinc oxide in a gallon of water in
1 which have previously been dissolved 20 oz. of
alum. It is used warm or hot. One cell will be
sufficient to deposit from it. The anode is zinc, and
the whole matter is exceedingly simple. All metals
take the coating.

Deposition of Tin.

Tin may easily be deposited by the simple-im-
mersion process :—Dissolve 1 oz. of chloride of tin
and 2 lbs. of ammonium alum in 5 gals, of water.
Heat the solution to boiling, clean the articles, and
immerse, moving about until they are perfectly
coated with tin. As the solution becomes ex-
hausted, add a little chloride of tin.

Also:—Dissolve the double chloride of tin and
sodium in water to saturation, and then dilute the
solution with twice its bulk of water. Articles
to be tinned in this solution must be immersed
in a zinc basket, or have tied to them chips of
zinc.

Small articles are rapidly coated with tin by
placing them in a solution of cream of tartar at
boiling temperature, and throwing in a quantity of
grain tin. The cream of tartar mixture must be
strong. It is better to arrange the grain tin in
layers upon copper or brass gauze, to place the
articles upon such surfaces, and to boil the liquid
—it is suited for coating brass and copper articles.20 8

ELECTRO-PLATING.

To make the chloride of tin, which should be
freshly prepared, heat some strong hydrochloric
acid, and add to it plenty of grain tin. As soon as
the action entirely ceases, the liquid is a saturated
solution of tin chloride—it may be crystallized, but
it is more convenient to use it as it is. Tin chloride
is also called stannous chloride.

Coloured Coatings for Metals.

Solution.—In a quart of pure water dissolve one
ounce of hyposulphite of soda. Stir into this
another solution made by dissolving an ounce of
acetate of lead in a pint of water.

For use, heat the solution in a glass or earthen-
ware pan to about 1950 Fahr., and immerse the
metal required to be coloured. The coating is one
of lead sulphide, and its depth of colour will depend
upon the time the metal is immersed. In a few
minutes brass articles qf small size may be coated
with any colour, varying from golden yellow to the
tint of clean copper or red gold, to carmine, down
to dark red; from light aniline blue to bluish
white, then to reddish white or brown.

It is not a good plan to plunge the articles into
the solution without previous preparation; it is
by far best to chemically clean them as for plat-
ing (see Preparation), and, before dipping in the
colouring liquid, to keep for a few minutes in hot
water, unless, indeed, the coating is to be a very
slight one. Steel and iron articles may also beCOLOURED COATINGS FOR METALS. 20q

treated, and given a fine blue colour1 without the
aid of such great heat as is necessary in u bluing "
or oxidizing. Copper articles do not, of course,
show the lighter tints. If the cleaning is well done,
the adhesion will be perfect, so perfect indeed that
the burnisher maybe used with impunity; but it
is not wise to use the scratch-brush. Instead of
burnishing, however, the surface may be finished
by a soft and smooth buff, which will impart a
lasting polish.

The solution will not keep long in the heated
state, as it deposits its sulphide upon the vessel's
bottom if no metals are present. It is stated that
an exceedingly beautiful red and green colouring
can be given to brass articles by omitting the lead,
and putting in its stead an equal weight of sulphuric
acid. If the immersion continues, the red changes
to a fine brilliant green, and then to green and
brown, with a splendid iris glitter. The coating is
very durable, unlike the others, which are best
lacquered over with pale lacquer.

Clean brass or copper may be covered with a
firmly adherent pure black coating by placing very
near to the flames of burning straw—it will not rub
off, and may be polished with a soft cloth.

PINDEX.

y^CTD, hydrochloric, 43
hydrocyanic, 43
hydrofluoric, 26
nitric, 44
sulphuric, 44
Aluminium, deposition of, 194—
197

solution of, 196

battery power for depositing,
196

Amalgamation of zincs, 56
Analysis of solutions (gold), 192

(silver), 147
Anodes, 4

of copper, 87
of silver, 138
of nickel, 159
of gold, 185
of brass, 200
of German-silver, 205
Articles, preparation of, 21—39

gATTERY, copper-zinc, 52
Bunsen, 52
Daniell, 54—56
Faller, 56

workshop — Smee, Daniell,
Bunsen, 50—72

Battery, for amateurs, 47—50
carbons for, 58
clamp-screws, 59
cells, 60
zincs, 57

strengths, 6s—64
management of, 64—69
remarks upon working, 69—7
cost of different kinds of, 70
power for silver-plating, 144
power for copper deposition, 10
for nickel-plating, 160—163
for gold-plating, 188
for aluminium. 197
for brass, 201
Binding screws, 59
Brass, deposition of, 197—202
anodes, 200
solutions of, 197—202
vats for solutions of, 201
batteries for plating with, 201
Bright silver-plating, 136
Britannia metal, preparation of, 25
Bunsen battery, 52

management of, 65
carbons for, 57
cost of, 70
Burnishing, 22, 23212

INDEX.

£ARBONS for batteries, 58

Care of gold solutions, 188
Casting nickel anodes, 159
Cells for batteries, 60, 61
Cell, depositing, 17—21
Smee, 50
copper-zinc, 52
Bunsen, 52
Grove, 54 (

Daniell, 54—50
Fuller, 56
porous, 61
Chemicals and materials, 39—46
Clamps for batteries, 59
Coating of ferns, 99
grass, 99
flowers, 99
insects, 99
Colour of the gold, 181 •

Coloured coatings for metals, 208
Composition, stopping off, 146

elastic, for moulding, 95
Conducting solutions, 97

surfaces, 104
Copies of coins, 98
Copper, preparation of, 24
removal of, 38
zinc cell, 52
deposition of, 82—112
zinc necessary in depositing,
-91

hints on depositing, 106—108
Current, regulation of, 71
Cost of batteries, 70, 71
silver-plating, 144
nickel-plating, 164
gilding, 193
Cyanide of potassium, 40—43

free, in silver-plating, 136—
Hi

£)ANIELL battery, 54—56

working of, 66—69
Dead dipping, 31
Density of silver solution, 142

Depositing vessels and vats, 17—21
Deposition of silver, 113—150
stopping off, 30
vessels, 17—21
cells, 17—21
of copper, 82—112
simple immersion, 84
time necessary in, 91
* of iron, 101—104
of copper, hints in, 106—in#
of nickel, 151—165
of aluminium, 195
of platinum, 202—204
of German-silver, 204—206
of zinc, 206
of tin, 207
of gold, 166—193
Dictionary of terms, 7—14
Dipping for bright gilding, 31

for dead gilding, 31
Distance to be maintained in gold-

plating, 186
Dynamo-electric machines, 74—81
work of, 77
cost of, 81

JTLASTIC composition, 95

Electric, dynamo, machines,

74—81
work of, 77
cost of, 81
Electro-plating, applications of, 2

motive force, 61—64
Electrotypes, 91—101

from engraved plates, 99—101
from set-up type, 106—112
rapid, production of, 108 —
112

Engraved plates, electrotypes from,
99—101
steel-facing, 101—104

JT AC-SIMILES of coins, 98
Failures and faults, 36, 37INDEX.

213

Ferns, coating of, 99
Finishing plated goods, 146
Force, electro-motive, 61—64

regulation of, and current, 71,
72

Free cyanide in gold solutions, 187
silver solutions, test for, 139—
141

Fuller battery, 56
Fulminate of gold, 180
Fusible alloy, 94

GALVANOMETER, the, 72
German-silver, deposition of,

204—206
preparation of, 24
Gilding, cost of, 193

by simple dipping and battery,

166—193
by simple dipping, 169
by battery, 173
solutions for, 169—181
anodes for, 185
battery power for, 188
time necessary in, 186
steel and iron, 187
German-silver, 187
bright, dipping for, 31
dead, dipping for, 31
dead, 183

colours in electro, 181—185
Glass specula, silvering of, 121—126
Gold, to remove, 38
Gold-plating, 169—191

solution, analysis of, 192
solutions, 169—181
colour of the, 181—185
anodes, 185

solutions, free cyanide in, 187

care of, 188
recolouring of, 188
Goods, finishing plated, 146

preparation of manufactured*
24

Gramme machine, 77—81

Grove battery, 54
working of, 69

JOINTS and suggestions in copper

depositing, 106—108
Hydrochloric acid, 43
Hydrocyanic acid, 43
Hydrofluoric acid, 26
Hydrogen, sulphuretted, 44
Hydrometers, 45

JNFERIOR work, gilding of,
187

Insects, coating of, 99
Intensity, 72

Internal resistance of batteries, 64
Iron and steel, gilding of, 187
preparation of, 25, 29
cast, preparation of, 26
Iron, deposition of, 101—104

J^ATHE, scratch-brush, 28
Lead, preparation of, 25
removal of, 38
Liquids, dipping, 25—27

j^JACHINES, dynamo-electric, 74
—81

Management of silver solutions, 138
batteries, 64—69
copper solutions, 87
nickel solutions, 160
gold solutions, 187
iron solution, 101—104
brassing solution, 199
Manufactured goods, preparation of,
24

Materials and chemicals, particulars

of, 39—46
Mercury, 44

solutions for quicking, 27
Metallic nickel, 152
Metals, coloured coatings for, 208
Moulding composition, gutta-per-
cha, 93214

INDEX.

Moulding composition, elastic, 95
Motion in solutions, 33

JN^ICKEL, deposition of, 151—165
plating, 153—165
plating, simple, 153
salts of, 151
metallic, 152
grain, 152

plating by battery, 154—164
solutions, 154—159
anodes, 159
casting, 159
anodes, casting of, 159
solutions, management of, 160
plating-room, 163
plating, cost of, 164
peculiarities of electro-depo-

sited, 164
recovery of, from old solutions,

165

alloy, plating with, 205
Nitric acid, 44

Non-conducting surfaces, 106

QLD work, preparation of, 37

silver solutions, recovery
from, 148
nickel solutions, recovery from,

165

gold solutions, recovery from,
191

Ornamentation of silver, 145

metals, 208
Oxidized silver, 145

PECULIARITY of electro-de-
posited nickel, 164
Pink gold, 182
Plaster of Paris, 95
Plated goods, finishing of, 146
Plating, silver, simple, 116—120
silver, 126—138
silver, bright, 137
silver, time required in, 143

Plating, silver, battery power for,'144
silver, cost of, 144
nickel, 151—165
nickel, simple, 153
nickel, by battery, 154—159
nickel, room, 163
nickel, cost of, 164
gold, 166—193

distance to be maintained in, 186
gold, battery power for, 188
gold, cost of, 193
gold, solutions, analysis of, 192
with zinc, 207
German-silver, 204—206
nickel alloy, 205
tin, 207
room, the, 15
copper, 85—90
Platinising plates, 203
Platinum, solutions for depositing,
203

deposition of, 202—204
salts of, 202
Plumbago, 104
Porous cells, 61
Position in solutions, 34, 35
Potassium, cyanide of, 40—43

carbonate of, 40
Power, battery, for gilding, 188
depositing aluminium, 196
Preparation of manufactured goods,
24

copper, 24
German-silver, 24
brass, 24

steel and iron, 25—29
tin, 25
lead, 25
pewter/ 25
Britannia metal, 25
cast iron, 26
old work, 37
Preparatory solution, 96
Prussic acid (hydrocyanic acid), 43
Purchase of materials, 46INDEX.

215

QUALITY of silver solutions, 135

Quantity, definition of, 72
Quicking articles, 27

solutions, 27
Quicksilver (mercury), 44

J^APID electrotyping, 108—112
Recovery of nickel from old

solutions, 165
gold, 191
silver, 148—150
Recolouring of gjlt^id gold goods,
188

Regulation of force and current, 71,
72

Remarks upon batteries, 69—72
Removal of silver, 38
gold, 38
copper, 38
zinc, 38
lead, 38

gALTS of copper, 82—84
silver, 113—116
nickel, 151, 152
gold, 166—169
Scratch-brushes, i6> 17 '

Screws, battery, 59
Set-up type, electrotypes of, 106—
112

Silver, removal of, 38

deposition of, 113—150
salts of, 113—116
plating, simple, 116—120
glass specula, 121—126
solutions, making of, 126—137
solutions, management of, 138
plating, 126—138
solutions, analysis of, 147
plating, bright, 137
solutions, free cyanide in, 136
solutions, density of, 142
plating, time required in, 143
^ battery power for, 144
cost of, 144

Silver, ornamentation of, 145, 146
oxidized, 145

plated goods, finishing, 146
solutions, recovery from, 148—

150

Simple copper-plating, 84
nickel-plating, 153
gold-plating, 169
batteries, 47
Smee battery, 50

working of, 64
Steel-facing electrotypes, 101—104
Steel and iron, preparation of, 25—29
Suggestions and hints in depositing

copper, 106—108
Sulphuric acid, 44
Sulphuretted hydrogen, 44
Surfaces, conducting, 104—106

non-conducting, 106
Syphons, 45

'pELESCOPE specula, to silver,

121—126
Terms, explanation of, 7—14
Thermometers, 45
Time required in depositing copper,
9i

silver, 143
gold, 186
Tin, deposition of, 207
Treatment of spoilt solutions, 148,

165, 191
Type, set-up, to copy, 106—112
Typing, electro-, 91—101

yARNISH, stopping off, 146
"Viats and depositing vessels, 17
—21
for brassing, 201
Vessels, depositing, 17—21, 201

"^TAX moulds, 97

Weston dynamo-electric ma-
chine, 78—80
Wiring the articles, 32, 33216

INDEX.

Wood engravings copied, 108
Work of dynamo-electric machines,
77

Working of Bunsen cell, 65, 66
Daniell, 66—69
Fuller, 69
Grove, 69

Working of Smee cell, 64
Workshop batteries, 50—72

2INC, deposition of, 206
for batteries, 57
amalgamating, 56 / o

THE END.

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