IMPROVEMENTS IN COVERING OR COATING CERTAIN METALS WITH PLATINA, AND ALSO IMPROVEMENTS IN GILDING CERTAIN METALS, AND IN APPARATUS USED IN SUCH PROCESSES
Year: 1837

page_text: TO ALL TO WHOM THESE PRESENTS SHALL COME, I, HENRY
ELKINGTON, of Birmingham, in the County of Warwick, Gentleman, send
greeting.
WHEREAS His late most Excellent Majesty King William the Fourth,
by His Letters Patent under the Great Seal of Great Britain, bearing date
at Westminster, the Seventeeth day of February, in the seventh year of His
reign, did for Himself, His heirs and successors, give and grant unto me,
the said Henry Elkington, His especial licence, 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 Invention of "IMPROVEMENTS IN COVERING OR
COATING CERTAIN METALS WITH PLATINA, AND ALSO IMPROVEMENTS IN GILDING
CERTAIN METALS, AND IN APPARATUS USED IN SUCH PROCESSES;" in which said
Letters Patent is contained a proviso that I, the said Henry Elkington,
shall cause a particular description of the nature of my said Invention, and in
what manner the same is to be performed, to be inrolled in His 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.

page_text: NOW KNOW YE, that in compliance with the said proviso, I, the said
Henry Elkington, do hereby declare the nature of my said Invention, and the
manner in which the sanie is to be performed, are fully described and ascer-
tained in and by the following description thereof (that is to say) :-
My improvements in coating or covering certain metals with platina or
platinum, consists in the use of carbonate of potash or soda (either separately
or mixed) in the manner herein-after described; and my improvements in
gilding certain metals, consists, first, in gilding certain metals, which are to
be first coated with platinum, by a solution of gold hereafter described; and,
secondly, in a method of gilding certain metals by means of a solution of
mercury and a solution of gold; and my improvement in the apparatus used for
such purposes consists of the application of an apparatus suitably constructed
for evaporating the waste waters, in order to concentrate the solutions of gold
contained therein.
I shall now describe my improved process of coating certain metals with
platina or platinum. I dissolve the platinum in nitro-muriatic acid, composed
of equal measure of nitric acid, pur, (specific gravity 1.45), and muriatic acid,
pur, (specific gravity 1.15), (the quantity of acids sufficient to dissolve one
ounce of platinum I have found to be about ten ounces by measure of each of
the acids), which I keep at a gentle heat until the plátinum is dissolved;: and
I prefer afterwards to evaporate the liquid until it is reduced to one half, or
thereabouts. To one ounce of platinum thus dissolved add three quarts of
pure water, and three pounds of bicarbonate of soda, and boil.them until the
soda is dissolved. Then add gradually one pound of bicarbonate of potash,, and
boil them together for about half an hour; a piece oficlean brass or copper put
into this mixture (which should be kept boiling when used) will suffer little or
no change. But if there be added to it a small portion, from one, to five penny-
weights of gold in solution (prepared as hereafter described), the metal, afterwards
placed in this boiling mixture will be coated with platinum apparently in a non-
metallic state, (but which coating will be increased:by remaining:à longer, time:
in the boiling mixture), producing various.colors resembling bronze, varying with
the proportion of gold added to the mixture, and with the length of time they
remain in it, and by adding a larger proportion of.gold the metals may be coated
with platinum in a metallic. state, and which will resist the, action of nitric
acid, but for this purpose I prefer to use the following: process. Dissolve one
ounce of fine gold in six ounces (by measure) of nitro-muriactic acid, composed
of three ounces nitric acid, pur, (specific gravity:ll 45), and three ounces muri-
atic acid, pur, (specific gravity 1.15), and continue to beat the same after the
gold is dissolved: until a yellow or reddish vapour ceases to arise, add. to this

page_text: three quarts of pure water and four pounds bicarbonate of potash, and boil them
together for about half an hour; then, having the articles to be coated with
platinum made perfectly clean and free from grease, add to the boiling solution
of potash and gold a small quantity of platinum (say about one pennyweight) in
solution, or as little as is found sufficient, put in the articles to be coated (first
stirring the mixture), and they will be found sufficiently coated in a few.
seconds, or varying from a few seconds to a minute, according to the quality,
and purpose of the articles. I usually prepare the solution of platinum used:
in this process, before it is added to the solution of gold and potash, by,
boiling the platinum with bicarbonate of soda, say to one ounce of platinum.
dissolve as above, add one pint of pure water and as much bicarbonate
of soda as will dissolve at boiling heat. In employing this process I
have found it adviseable to add the platinum at intervals, and in quantity
varying in proportion to the quantity of work to be done, always
using as little of the platinum as is found to be sufficient to produce the
desired effect: If in operating the articles assume a reddish appearance, it
arises from not having sufficient platinum in the mixture, in which case the
gold appears to alloy itself with the platinum. The operator should therefore
add more platinum when he finds this to be the case. And I would further,
observe, that these processes are subject to considerable variation, both in
proportions of the ingredients used as well as in the manner of operating, the
effect produced varying accordingly, and according to the time the articles
remain in the mixture. And it will be necessary for the operator first to
ascertain the mode of treatment necessary to produce any particular color or
effect he may desire, by dipping portions of the metal into the mixture, and
observing the effect produced, and afterwards proceed accordingly. These
observations relate to the coating metals with platinum (in a metallic state).
and also to the production of different colors herein described.
"
In describing my improvements in coating certain metals with platinum,
I have given such directions for dissolving the platinum and the gold as are
to the best of my knowledge the most suitable for the purposes, and, which I
have found to answer, but I would have it understood that I make no claim
to the method of dissolving the platinum or the gold, nor do I confine myself.
to the precise means of producing the solutions; but what I do claim as my
Invention of improvements in coating certain metals with platinum, is the use
of the carbonates of potash or soda, or a mixture of them together with a
solution of platinum and a solution of gold, as herein described. Note.-
When the solution of gold and platinum has been used as long as it is found
to work well, the remaining gold and platinum may be recovered from the

page_text: solution, and separated and refined for further use, by any of the known
methods in use for that purpose.
I shall now proceed to describe my improvements in gilding certain metals,
and I shall first describe my method of gilding copper or brass first coated with
platinum. The articles to be gilded are first coated with platinum in the
manner herein-before mentioned and described for coating certain metals with
platinum in its metallic state; and when thus coated, I transfer them to a-
solution of gold prepared as follows:-Dissolve one ounce of fine gold in
six ounces nitro-muriatic acid (composed of three ounces nitric acid, pur,
specific gravity 1.45, and three ounces muriatic acid, pur, specific gravity
1 15), and keep the same at a gentle heat until the gold is dissolved,
and afterwards evaporate the solution until it is reduced to about one
half. This solution may be used without dilution, or it may be diluted
with water more or less, as it is found to answer best. The articles to be
gilded are to be dipped into this solution and allowed to remain therein until
sufficiently gilt. The necessary time will depend, first, on the quality of the
articles; secondly, on the strength of the solution; and, thirdly, on the
thickness of the coating of platinum. I have generally found that in a strong
solution of gold (say the solution described above, diluted with its own bulk
of water), the articles were gilded sufficiently by merely dipping them into
the solution and stirring them from two to three seconds. But all this the
operator will obtain by a little practice, taking care that the articles are
sufficiently coated with platinum to prevent the acid or the chlorine in the
solution of gold from corroding the copper or brass beneath, otherwise the
gold will be seen to peel off on those parts. The articles thus gilded have
a yellowish brown appearance, and require to be colored by the usual process
after gilding. The color I prefer to use is prepared as follows:-Take six
pounds saltpetre, six pounds alum, three pounds green copperas, three pounds
white vitrol. Boil the mixture with sufficient water to dissolve the salts,
and let it boil ten minutes. The articles are to be dipped into this color and
afterwards heated over a clear fire until the salts become brown, they are
then immersed in cold water; they will be of a fine gold color. This process
is also applicable to the gilding of certain ornamental work in parts, the same
being coated with platinum. The gold may be applied to the parts required
to be gilded with a brush or hair pencil, or, which I prefer, by covering
the parts not to be gilded after it is coated with platinum with varnish
or lacquer, and when dry the articles may be dipped into the solution of
gold, as before directed. The lacquer or varnish may then be removed by
ineans of spirit of wine or turpentine, and the articles colored, as in the
1

page_text: former case. The articles thus treated may be burnished in part, or otherwise
as taste may direct, the platinum forming a groundwork or relief to the
gold, and giving a very beautiful and novel effect to the whole. Note.-In
place of using platinum, palladium may be employed for the first coating, but
I prefer platinum.
I would have it understood that I claim the mode herein described of
gilding certain metals by the application of a solution of gold to those metals,
they having been first coated with platinum or palladium, as above described.
I shall now describe a method of gilding certain metals by means of
solution of gold and a solution of mercury. Dissolve gold in nitro-muriatic
acid, as before directed, and evaporate the solution to about one fourth or
until it assumes a deep red color and crystallizes on becoming cold. The
solution may then be diluted with sufficient water to render it convenient to
measure off any quantity of the gold contained in the solution. Prepare also
a solution of mercury as follows:-Dissolve any quantity of mercury in nitric
acid, and to from two to four pennyweights of mercury in solution add a
gallon of water and three pounds of carbonate of potash, and boil them until
the potash is dissolved. The mercury will at first be precipated by the potash,
but when boiled together will afterwards will re-dissolve. Then having the
articles to be gilded made perfectly clean, take any convenient quantity of
them, and having measured off as much of the gold in solution as is considered
sufficient, put it into a clean earthen vessel capable of holding sufficient water
(I usually employ from two to six grains of gold to one pint of water); then
dip the articles into the boiling solution of mercury and potash, when they
will immediately. be coated with mercury (a very slight coating will suffice),
wash them in clean water and pass them into the solution of gold diluted,
as before described, keeping the liquid in motion and occasionally stirring
about the articles. The gold will be seen to alloy itself with the slight
coating of mercury, and the articles will become of a greenish bronze
appearance; when this appearance is the same over the whole surface of the
goods, they may be passed again into the solution of mercury and potash, and
the process repeated. as before, until they are sufficiently gilt. They must
then be put into the solution of mercury and potash (which may have
more mercury in this instance), and when uniformly white over the whole
surface, they must be heated over a clear fire until all the mercury
is expelled (a process called heightening, and well understood in the
In gilding by these means, the operator
ordinary method of gilding.
must guard against having the solution of gold too strong, and the coating of
mercury should be proportioned to te strength of the solution of gold, all

page_text: which he will best understand by a little practice, as the quantities employe
in both cases may be varied considerably with the same. result, .or nearly so
I would remark, that I prefer to gild by this process only such articles as ar
required of an inferior quality, and for such goods this process has many
advantages over the old method of gilding by amalgam of gold and mercury
the gold being more uniformly spread over the whole surface of the articles
and the operation is performed without injury to the workman employed.
Having now described my improvements in gilding certain metals, I would
have it understood that I make no claim to the method herein described of
preparing the solutions of gold or the solution of mercury, and they may be
varied. I am aware that other solutions of gold and mercury may be
prepared, differing in some degree from those I have described, but capable
of producing similar results.
What I claim as the second part of my Invention is, the using of a solution
of mercury and a solution of gold in place of the amalgam of gold and
mercury heretofore employed. Note.-The pound employed is the averdupois;
the ounce of gold or platina, the troy; the quart and pint, the imperial; and
the ounce of fluids, the apothecary's fluid ounce or the twentieth part of
the imperial pint in the above direction. And note, in speaking of certain
metals, I wish it to be understood that I mean copper, brass, or such other
alloys known by the name of gilding metals, and German silver.
My improvements in apparatus consists of a boiler and condenser for evapo-
rating in vacuo the waste waters with which the gilded articles are washed after
they are taken out of the solution of gold and potash, and thereby rendering the
gold and potash contained in such waters in a fit state for use, and my object for
evaporating such waters in vacuo is to prevent the precipitation of the gold, which
I have found to take place when gold is boiled at a high temperature with a
dilute solution of potash. In the annexed Figure, a is the boiler, having a fur-
nace b, with stopcock, for the purpose of supplying the boiler as the evaporation
proceeds, and a valve at c (for safety), which is kept closed by the external
pressure; d is a pipe leading to the condenser, having a small cover g
attached, which is fastened steam tight to the lid of the boiler by bars and
screws, as seen in the Drawing. The lid of the boiler is fixed by rivet
or screws, and the small cover is taken off for convenience of emptying the
boiler. e is the condenser, having a top and bottom space h, h, connected by a
tubes, through which the steam passes and is condensed, the tubes being
surrounded by a constant flow of cold water. i is a pipe leading from the
lower chamber to the air pump f, which is used to exhaust the vessels and to
pump out the condensed water occasionally. The condenser and air pump

page_text: ay be placed in a vessel of cold water, and a stream of cold water caused to
ow through the tubes constantly.
In witness whereof, I, the said Henry Elkington, have hereunto set my
hand and seal, this Seventeenth day of August, in the year of our
Lord One thousand eight hundred and thirty-seven.
AND
REMEMBERED, at on the Seventeen
August,
the year of our Lord 1837, the aforesaid Henry Elkington came before our
said Lady the Queen in Her Chancery, and acknowledged the Specification
O aforesaid, 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 Seventeenth day of August, in the year of our Lord One
thousand eight hundred and thirty-seven.