CERTAIN IMPROVEMENTS IN GILDING AND SILVERING CERTAIN METALS, "AND ALSO FOR IMPROVEMENTS IN CERTAIN VESSELS OR APPARATUS USED IN SUCH PROCESSES, AND FOR OTHER PURPOSES
Year: 1837

page_text: ELKINGTON'S SPECIFICATION.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, HENRY
ELKINGTON, of Birmingham, in the County of Warwick, Gentleman, send
greeting.
WHEREAS Her present most Excellent Majesty Queen Victoria, by Her
Letters Patent under the Great Seal of Great Britain, bearing date at West-
minster, the Fourth day of December, in the first year of Her reign, did, for
Herself, Her heirs and successors, give and grant unto the said Henry Elking-
ton, Her especial license, full power, sole privilege and authority, that I, the
said Henry Elkington, my exors, admors, and assigns, or such others, as I, the
said Henry Elkington, my exors, admors, or assigns, should at any time agree
with, and no others, from time to time and at all times during the term of
years therein expressed, should and lawfully might make, use, exercise, and
vend, within England, Wales, and the Town of Berwick-upon-Tweed, my Inven-
tion of "CERTAIN IMPROVEMENTS IN GILDING AND SILVERING CERTAIN METALS,
"AND ALSO FOR IMPROVEMENTS IN CERTAIN VESSELS OR APPARATUS USED IN SUCH
PROCESSES, AND FOR OTHER PURPOSES;" in which said Letters Patent is contained
proviso, that I, the said Henry Elkington, shall cause a particular description.
of the nature of my said Invention, and in what manner the saine is to be
performed to be inrolled in Her said Majesty's High Court of Chancery
within six calendar months next and immediately after the date of the said in
part recited Letters Patent, as in and by the same, reference being thereunto.
had, will more fully and at large appear.
NOW KNOW YE, that in compliance with the said proviso, I, the said
Henry Elkington, do declare that the nature of my said Invention, and the

page_text: manner in which the same is to be perforined, are particularly described and
ascertained in and by the following statement thereof (that is to say) :-
My Invention relates to the gilding and silvering of such metals and alloys
and combinations of metals as may be required to be gilt or silvered, and
consists, first, in a method of gilding metals by certain solutions of gold
herein-after specified; secondly, in a method of silvering metals by means of
certain solutions of silver herein-after specified; and, thirdly, my improve-
ment in certain vessels or apparatus consists of a method of coating metallic
vessels used in the above-mentioned processes, or for other purposes, with an
enamel or a vitrious mixture capable of forming, when fuzed, a glaze or
enamel, the purpose intended being to protect such vessels from the action
of acids or other matters employed therein.
And in order that my Invention may be more fully understood, I shall
proceed to describe the different methods of operating, which according to my
present experience, I believe to be the best for the purposes.
For the purpose of gilding metals, I prepare a solution of gold as follows:-
Dissolve one ounce troy weight of fine gold in nitro-muriatic acid composed of
three fluid ounces of nitric acid (specific gravity 1-45), and three fluid ounces
of muriatic acid (specific gravity 1-15), and three ounces distilled water;
when dissolved, dilute with water to about two quarts, then precipitate the gold
by adding a solution of two ounces of silver in one fluid ounce of nitric acid
diluted with two ounces of water, and afterwards further diluted with two
quarts of water, wash the precipitate and redissolve the gold by adding ten
ounces avoirdupois of chloride of sodium (common salt), dilute the solution
with about three quarts of water, and filter. To the solution of gold prepared
as above I usually further add twenty ounces avoirdupois of chloride of sodium
and twenty ounces avoirdupois borax (borate of soda), or thereabouts, and boil
the whole for a quarter of an hour before use. If the gilding is wanted of a
paler color than is produced by the above mixture, it may be obtained by
adding a very small quantity of chloride of silver to the solution of gold.
I sometimes employ other salts of sodium or potassium, such as the sulphates,
nitrates, &c. with the borates of soda or potash in the manner above described,
but what I prefer is the mixture of the borax and chloride of sodium, and I
sometimes employ a solution of gold, prepared by dissolving one ounce
troy weight of fine gold in aqua regia, composed of two fluid ounces
nitric acid (specific gravity 14-5) diluted with three ounces of water, and
three ounces avoirdupois of chloride of sodium. To this solution of gold I
usually add twenty ounces avoirdupois of borax and thirty-two ounces of
chloride of sodium, with water sufficient to dissolve the salts. Note.-The

page_text: solution of gold should be boiled first with the borax for fifteen minutes, after-
wards add the chloride of sodium, and boil for half an hour. I then proceed
with the gilding in the following manner:-The articles to be gilded having
been first perfectly cleaned from scale or grease, they are to be suspended
on wires conveniently for a workman to dip them in the liquid which is kept
boiling.
The time required for gilding any particular article will depend on circum-
stances; partly on the quantity of the gold remaining in the liquid, and partly.
on the size and weight of the article, but a little practice will readily produce
sufficient judgment to the workman. Supposing the articles desired to be gilded.
to be brass or copper buttons, or small articles for gilt toys or ornaments of dress,.
such as earrings or bracelets, a considerable number of them may be strung
on a hoop, or bended piece of copper or brass wire, and dipped into the vessel-
containing the boiling liquid above described, and moved therein, and the re-
quisite gilding will be generally obtained in from a few seconds to a minute..
This is when the liquid is in the condition above described, and depending
on the quality of the gilding desired; but if the liquid has been used some
time, the quantity of gold will be lessened, which will vary the time of operating.
required to produce a given effect or color, and by observing the appearance of
the articles from time to time, the operator will know when the desired object
is obtained, though it is desirable as much as possible to avoid taking the
articles in and out of the liquid. When the operation is completed, the work-
man perfectly washes the articles so gilded with clean water; they may then be
submitted to the usual process of coloring. If the articles be cast figures of
animals, or otherwise of considerable weight compared with the articles above
mentioned, the time required to perform the process will be greater. In case
it is desirable to produce what is called a dead appearance, it may be performed.
by several processes. The one I usually employ is to dead the articles in the.
process of cleaning; as practised by brassfounders and in other trades, and it
is produced by an acid prepared for that purpose sold by the makers under the,
term deading acquafortis, which is well understood. It may also be produced.
by a weak solution of nitrate of mercury applied to the articles previous to the
gilding process, as is practised in the process of gilding with mercury previous
to spreading the amalgam, but generally a much weaker solution; or the
articles having been gilded, may be dipped in a solution of nitrate of mercury::
and submitted to heat to expel the same, as is practised in the usual process
of gilding. It is desirable to remark, that much of the beauty of the result-
depends on the well cleaning of the articles, and it is better to clean them by the
ordinary processes and at once pass them into the liquid to be gilded. I-have.

page_text: always employed the usual means for cleaning the articles from scales and other
impurities, which are commonly resorted to in working of the metals for other
purposes, where the surfaces are required to be free from scales or other
impurities, and I would remark that great care should be observed in pur-
chasing the article above described of the best description.
The proportions of ingredients above given, as also the methods of preparing
the several solutions, may be varied more particularly, according to the metals
to be gilded. I do not, therefore, confine myself to the exact methods set
down or proportions herein specified, although I believe them to be the best
for the purpose; and I have to observe here that the directions herein given are
more particularly adapted to the gilding of copper and its alloys, but as there are
other metals required to be gilt, I will proceed to give the best information in
my power to effect this object. Thus, if I desire to gild silver, I usually
employ the solution of gold last stated, and also the same proportions of the
salts, and I allow the silver articles to remain therein until they assume a pale
gold colour, and which is generally the case in one or two minutes. I then
transfer them to a mixture prepared as follows, that is to say, I add to the
mixture of gold and salts last above named, for one ounce of gold ten ounces
each of nitrate of potash and alum, and boil them together half-an-hour before
using, the previously gilt silver work being put into this mixture (boiling);
they hereby receive a stronger coating of gold, and the color and effect is
improved.
Again, if I desire to gild iron or steel, I usually dissolve borax in the solution
of gold, as before described, for one ounce of gold in solution I use four ounces
of borax, and when the solution assumes a greenish color I add a quarter of
a pound of nitrate of potash or of chloride of sodium, or as much as I find
to answer the purpose, which will depend in some degree upon the nature of
the articles.
In the same manner zinc and other metals may be gilt by adapting the
solution of gold to the nature of the metal to be operated on with zinc; I have
succeeded best by employing the solution of gold prepared with borax only, and
I usually employ a more dilute solution of gold and a larger proportion of the
borax.
By attention to the above instructions, the operator will be able to vary the
mixture of salts to suit the different metals he may require to gild.
For the purpose of gilding metals with a solution of gold and ammonia, I
proceed as follows:-If I use the solution of gold first mentioned in this my
Specification, I usually add thereto for one ounce troy weight of fine gold in
solution twenty ounces avoirdupois of muriate of ammonia, and one penny-

page_text: weight of bichloride of mercury or corrosive sublimate (but do not confine
myself to these proportions), and I boil the mixture until the salt is dissolved
and during the process of gilding. If I use the solution of gold last mentioned
I add thereto for the one ounce of gold four pounds avoirdupois of muriate of
ammonia, and half a pound avoirdupois of carbonate of ammonia (or sufficient
to neutralise the acid contained in the solution of gold), and one pennyweight
and a half of bichloride of mercury (more or less) of each, as is found to
answer the purpose best.
On adding the carbonate of ammonia, as last described, to the solution of
gold, if there be an excess of the carbonate, the gold will be precipitated in the
state of a brownish yellow powder, and during the time that the solution con-
tains an excess of carbonate of ammonia, I have not found the gilding answer
so well. By the continued boiling of the mixture, or by the addition of a
sufficient quantity of nitric acid, the excess of the carbonate is removed, and
the precipitate redissolved; I then proceed with the gilding.
The metals to be gilded being dipped into the solution of gold above
described will be coated with gold almost instantaneously, but the color,
instead of being yellow, will be red, more or less deep, and and suitable for
that kind of gilding, called red gilding, but if the same be wanted of a yellow
gold color, the change will be produced by coloring the work so gilt in the
usual manner.
I would here observe, that though I have described certain quantities of
the different ingredients as being the best I am acquainted with for the pur-
pose, the same may be varied, as also the manner of preparing the solution of
gold, the proportions of the ingredients varying accordingly. If I find it con-
tains free acid, I add a small portion of the carbonate of ammonia, or if instead
of being a clear red, the articles dipped in blacken, and on coloring assume a
stained reddish brown appearance, I add a small portion of the bichloride of
mercury, or if too concentrated a little water, but if after the coloring the
color is too pale or looks whitish, it is in consequence of having too much of
the bicholoride of mercury. By observing the effects above mentioned, the
workman will readily adjust his mixture to suit the work he may have in
hand.
.
What I claim as my Invention is the application of a solution of gold com-
bined with any convenient salts, preferring those of potassium or sodium or
ammonia (excepting carbonate of potash or soda), giving the preference to
chlorides of potassium and sodium, with the borates, and with muriate of
ammonia, for the purpose of gilding metals as above described.

page_text: I will now proceed to describe my improvements in silvering metals. I
take any quantity of silver and dissolve it in nitric acid, as is well understood,
and after diluting the solution with about a gallon of water to every ounce of
silver dissolved, precipitate the silver in a state of chloride by the addition of
chloride of sodium, or other suitable means. If the work to be silvered is of
inferior quality, I provide any convenient quantity of concentrated muriatic
acid, and add thereto as much of the chloride of silver as will dissolve in the
acid, boiling the acid for a quarter of an hour. When cooled it is fit for use.
The articles to be silvered are to be well cleaned, and should be dipped in
aquafortis, and being well washed, passed immediately into the solution of
silver, stirring or moving the articles until sufficiently coated, which will gene-
rally be the case in from a few seconds to a minute. This solution of silver
may be used for a length of time, care being taken to keep an excess of silver
in the solution by adding from time to time portions of the chloride of silver
in proportion as the solution is used, always keeping more of the chloride in
the mixture than will dissolve cold. Note.-If it is found inconvenient to boil
the acid, it may be prepared cold by adding to the acid an excess of the
chloride of silver, and stirring them occasionally for twenty-four hours before
using. For the better class of goods, such as are usually silvered by the pro-
cess called "hot silvering," and also such as are manufactured from rolled
plated metal, I prepare a solution of silver by dissolving the chloride of silver
in a solution of any convenient salt, preferring chloride of sodium or potas-
sium, and muriate of ammonia. I usually employ muriate of ammonia in the
manner following:-To one pound avordupois of muriate of ammonia add one
ounce troy of chloride of silver, two pennyweights of bichloride of mercury,
more or less, and water sufficient to dissolve the salts, boiling them together
half an hour, or until the chloride of silver is dissolved. This solution is kept
boiling while used, and the articles to be silvered being first cleaned, are put
into the mixture, and moved therein until sufficiently coated, according to the
degree required. The quantity of silver dissolved by this mixture is much
greater than that dissolved by the muriatic acid, and the coating of silver is
proportionably strong. Note.-The quantity of bichloride of mercury necessary
will depend upon the metal employed. The proportion above given is calculated
for copper; but for brass I use from four to five pennyweights; but in both
cases the operator should occasionally add more chloride of silver according as
the solution becomes weakened by using, and also of the bichloride of mercury.
In operating, if the coating of silver appears unsound and peels off the metal,
or is deposited in the state of loose powder, more bichloride of mercury must

page_text: be added, which the operator with a little practice will readily adjust. The
articles thus coated should be submitted to a temperature sufficient to expel
the mercury, and afterwards quenched in diluted muriatic acid.
Having now described my improvements in relation to the silvering metals,
I would have it understood that I do not claim as new the use of any of the
materials separately herein described for the purpose of silvering; and I am
aware that a process of silvering metals has been before practised by usin
salts and a chloride of silver in the state of paste, which is applied by being
rubbed or brushed over the surface of the metal to be silvered. I do not
therefore claim the same; but what I claim is the mode of silvering by the
application of a solution of chloride of silver instead of a paste, and dipping in
place of rubbing.
I will now proceed to describe my improvement in certain vessels or appa-
ratus, &c., and which consists in a method of glazing the inner parts of iron or
other metal vessels used in the processes above mentioned, and which I intend
to apply to other purposes, such as coating vessels for culinary purposes, and
for protecting such apparatus from the effects of acid or other destructive
agents employed therein, and which I perform in the manner following:-I
mix together two parts of carbonate of potash, or an equivalent quantity of
potash, soda, or carbonate of soda, two parts of fine clay (pipe clay or porce-
lain clay), and eight parts fine sifted sand, and reduce them with water to the
consistence of thick cream. The vessel is first coated with this mixture by
putting a portion in the vessel, and turning it about until it is equally covered,
the reside is then poured off, a sufficient quantity adhering to the iron. The
vessels thus coated are then set aside that the coating may dry slowly, and when
quite dry are submitted to a red heat, by which the mixture, which I call the
inner coating, is partially vitrified and adheres more firmly to the iron or other
metal. Note.-It will not be considered necessary to adhere precisely to the pro-
portions of the ingredients above mentioned, indeed the ingredients themselves
may be in some degree varied without departing from the nature of my Inven-
tion, the object being to obtain a semivitrified coating, which will adhere to the
iron and form a slow conductor of heat between the iron and the outer glaze.
Upon this inner coating I apply the outer glaze, which may be either a mixture
capable of forming a glaze when fused in the manner of glazing pottery wares,
or, which I prefer, powdered glass or enamel mixed with a small portion of clay
to give the proper consistence and render it adhesive. This is applied in the same
manner as the former coating, and fused thereon, by which means a compact
surface is obtained impervious to moisture, and which by means of their inner

page_text: coating is rendered capable of expanding and contracting with the iron or
other metal without injuring its texture, or in some instances, I prefer to
blow a thin coating of glass upon the inner coating.
In witness whereof, I, the said Henry Elkington, have hereunto set my
hand and seal, this Fourth day of June, in the year of our Lord One
thousand eight hundred and thirty-eight.
AND BE IT REMEMBERED, that on the Second day of June, in the
year of our Lord 1838, the aforesaid Henry Elkington came before our said
Lady the Queen in Her Chancery, and acknowledged the Specification afore-
said, and all and every thing therein contained and specified, in form above
written. And also the Specification aforesaid was stamped according to the
tenor of the Statute made for that purpose.
Inrolled the Fourth day of June, in the year of our Lord One thousand
eight hundred and thirty-eight.