IMPROVEMENTS IN THE TREATMENT OF METALLIC SURFACES FOR THE PURPOSE OF PRESERVING THE SAME FROM OXIDATION, AND OF IMPARTING TO THEM LUSTRE, IRIDESCENSE, AND OTHER ORNAMENTAL AND USEFUL PROPERTIES, PARTS OF WHICH IMPROVEMENTS ARE ALSO APPLICABLE TO THE TREATMENT OF OTHER SURFACES
Year: 1880

page_text: ETTERS PATENT to John Henry Johnson, of 47, Lincoln's Inn Fields, in the
County of Middlesex, Gentleman, for an Invention of "IMPROVEMENTS IN
THE TREATMENT OF METALLIC SURFACES FOR THE PURPOSE OF PRESERVING
THE SAME FROM OXIDATION, AND OF IMPARTING TO THEM LUSTRE,
IRIDESCENSE, AND OTHER ORNAMENTAL AND USEFUL PROPERTIES, PARTS OF
WHICH IMPROVEMENTS ARE ALSO APPLICABLE TO THE TREATMENT OF OTHER
SURFACES." A communication from abroad by William Ward, temporarily
residing at Brussells, in the Kingdom of Belgium.
PROVISIONAL SPECIFICATION left by the said John Henry Johnson at the
Office of the Commissioners of Patents on the 12th August 1880.
JOHN HENRY JOHNSON, of 47, Lincoln's Inn Fields, in the County of Middlesex,
Gentleman. "IMPROVEMENTS IN THE TREATMENT OF METALLIC SURFACES FOR
THE PURPOSE OF PRESERVING THE SAME FROM OXIDATION, AND OF IMPARTING
TO THEM LUSTRE, IRIDESCENCE, AND OTHER ORNAMENTAL AND USEFUL
PROPERTIES, PARTS OF WHICH IMPROVEMENTS ARE ALSO APPLICABLE TO THE
TREATMENT OF OTHER SURFACES." A communication from abroad by William
Ward, temporarily residing at Brussells, in the Kingdom of Belgium.
This Invention relates chiefly to the treatment of metallic surfaces, and it has
for its objects preserving such surfaces from oxidation, and also imparting to them
properties by platinizing, gilding, bronzing, and similar processes, so as to obtain
iridescence, lustre, and other ornamental and useful effects, but the Invention
is also applicable to the ornamentation or treatment of other than metallic
surfaces.
In carrying out this Invention I proceed in the following manner :-
When it is required to protect the articles or objects to be operated upon from
oxidation I apply to them alkaline silicates or metallic silicates, or mixtures of the
same, before they are subjected to the processes hereinafter described. The alkaline
silicates may consist of silica and carbonate of potash, in conjunction or not with
soda, the whole being mixed together and melted, and then ground up with spirits
of turpentine or petroleum, or other oils. The metallic silicates may consist of

page_text: silica and red lead mixed and fused, the product being ground up fine with oil or
essence, or silicates of iron, copper, tin, manganese, baryta, bismuth, antimony.
nickel, uranium chromium, cobalt, and of other metals may be used.
The products are applied as a coating to the surfaces of the articles or objects
to be preserved from oxidation, and such articles or objects are then subjected to
an elevated temperature in a muffle or oven.
In order to impart lustre to metallic surfaces treated in the manner hereinbefore
described I platinize the same (whether in a crude condition or polished or
enamelled) by the direct application of platinum, which is reduced by essential or
other oils, is purified free from its acids by ammonia, and held in solution in
rectified ether, alcohol, or spirits.
In carrying this part of my Invention into effect I pulverize very pure crystal-
lized chloride of platinum and heat the same so as to dispel all moisture. I next
mix the powder thus formed with pure essence of lavender, and gas is evolved. I
then (after reducing the product to a fine state of division) add gradually a sufficient
quantity of liquid ammonia, thoroughly stirring the mixture, and when the reaction
which takes place has subsided I remove all trace of ammonia by washing with
water. The platinum, combined with the essence of lavender, is thus completely
deprived of acid, and may be redissolved by rectified ether, alcohol, or other
spirits. The mixture may be applied to the surfaces of the articles or objects to
be platinized by the aid of a brush or by dipping, after which such articles or
objects are introduced into a muffle or oven, the heat of which is gradually raised
to a sufficiently elevated temperature, and they are taken out as soon as the muffle
or oven is cool.
When it is required to obtain iridescence as well as lustre in platinized articles
or objects I employ, in addition to platinum, sulphurous or metallic vapours or acid
vapours in the following manner-I grind with fatty essence of lavender a
quantity of chloride of platinum and German litharge, and coat the articles or
objects therewith, and when dry I place the articles or objects so coated in a
muffle or oven raised to an elevated temperature. As soon as the articles or
objects are found to have assumed a brilliant tint of silver or polished steel I
introduce some pure sulphur into the furnace, and after a short interval I introduce
a mixture of sulphur and an oxide of a metal (according to the tint required to be
imparted to the platinized surface), say, for example, oxide of copper. The sulphur
and copper become volatilized, and the fumes proceeding therefrom are allowed
to enter the muffle or oven containing the articles or objects under treatment so as
to act upon the platinum and litharge coating, whereby multicoloured effects of
iridescence are produced upon the articles or objects, which may then be removed
from the muffle or oven. In lieu of employing sulphur and a metallic oxide the
fumes of nitric acid or muriatic acid, or of the two combined, may be used.
The furnace is separated from the muffle or oven by means of removable
registers for the facility of regulating the admission of the fumes employed, and
when nitric acid or muriatic acid is used the articles or objects are preferably
placed upon shelves in a passage, through which a current of air flows, the acids
being caused to give off vapour by the application of heat, which vapour is con-
ducted by the air current and brought into contact with the said articles or objects.
It is obvious that the derivatives of platinum, as, for example, palladium, may be
used in lieu of platinum itself.
In order to obtain a gilded effect gold may be employed in conjunction with
platinum in the following manner :-
"
The articles or objects are first coated with a platiniferous composition, by
preference that known as lustre de platine brillant," and then baked in a muffle
After having been withdrawn the articles or objects are coated with a
gold liquid, by preference that known as "or brilliant sans brunissage,” and are
again baked.
or oven.
By these means brilliant gilding is obtained without burnishing or polishing in
a most economical manner, platinum (or one of its derivatives, as, for example,

page_text: palladium or irridium, being used as a primal coating, and being followed by a
coating of gold held in suspension or in solution. The gold may be held in solution
or in suspension in essences or essential or other oils, sulphurous or nonsulphurous.
It may also be applied by means of volatile oils, ether, and the like. Nickel may
in some cases be substituted for platinum. If desired platinum may be dispensed
with, gold being used alone, the object of using platinum being to economize the
gold.
My Invention is also applicable to platinizing and gilding vitrified or vitrifiable
products generally, such, for example, as porcelain, terra cotta, carthenware, pottery,
stone ware, crystal, glass, looking glasses, and the like.
When it is required to produce imitations of bronze upon metallic articles or
objects before the latter are gilded or platinized, I employ metallic powders, metallic
leaves, or oxides, which I apply to the surfaces of such articles or objects, or I may
apply to the said surfaces vitreous substances. For example, I apply to the surface
of the metals to be treated a coating of vitrifiable colours, such as are employed for
the decoration of porcelain, pottery, or glass, and then sprinkle on a coating of
metallic powder, which is caused to adhere by the application of heat. All shades
of colour, from green bronze to gold bronze, and also the imitation of old silver, may
thus be obtained.
The bronzed articles or objects may, if required, be subjected to gilding, silvering,
platinizing, nickeling, or similar processes by means of a battery or by simple
immersion.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said John Henry Johnson in the Great Seal Patent Office on the 9th
February 1881.
JOHN HENRY JOHNSON, of 47, Lincoln's Inn Fields, in the County of Middlesex,
Gentleman. "IMPROVEMENTS IN THE TREATMENT OF METALLIC SURFACES FOR
THE PURPOSE OF PRESERVING THE SAME FROM OXIDATION, AND OF IMPARTING
TO THEM LUSTRE, IRIDESCENCE, AND OTHER ORNAMENTAL AND USEFUL
PROPERTIES, PARTS OF WHICH IMPROVEMENTS ARE ALSO APPLICABLE TO THE
TREATMENT OF OTHER SURFACES." A communication from abroad by William
Ward, temporarily residing at Brussels, in the Kingdom of Belgium.
The said Invention relates chiefly to the treatment of metallic surfaces, and it
has for its objects preserving such surfaces from oxidation, and also imparting to
them properties by platinizing, gilding, bronzing, and similar processes, so as to
obtain iridescence, lustre, and other ornamental and useful effects, but the
Invention is also applicable to the ornamentation or treatment of other than
metallic surfaces.
According to the said Invention the before mentioned objects are effected in the
following manner:-
1. When it is required to protect metallic articles or objects from oxidation
I apply to them alkaline silicates or metallic silicates, or mixtures of the same.
The alkaline silicates may consist of silica and carbonate of potash in conjunction
or not with soda, the whole being mixed together and melted, and then ground
up with spirits of turpentine, or petroleum, or other oils. The metallic silicates
may consist of silica and red lead mixed and fused, the product being ground up
fine with oil, or essence, or silicates of iron, copper, tin, manganese, baryta,
bismuth, antimony, nickel, uranium, chronium, cobalt, and other metals may
be used.
The products are applied as a coating to the surfaces of the articles or objects to
be preserved from oxidation, and such articles or objects are then subjected to
an elevated temperature in a muffle or oven.
2. In order to impart lustre to metallic surfaces I platinize the same by the direct
application of platinum, which is reduced by essential or other oils, is purified, freed
from its acids by ammonia, and held in solution or suspension in rectified ether,
alcohol, or spirits. For this purpose I pulverize very pure crystallized chloride of
platinum and heat the same so as to dispel all moisture; I next mix the powder thus
formed with pure essence of lavender, and gas is evolved. I then (after reducing
the product to a fine state of division) add gradually a sufficient quantity of liquid
ammonia, thoroughly stirring the mixture, and when the reaction which takes place
has subsided I remove all trace of ammonia by washing with water. The platinum
combined with the essence of lavender is thus completely deprived of acid, and may
be redissolved by rectified ether, alcohol, or other spirits. The mixture may be
applied to the surfaces of the articles or objects to be platinized by the aid of a
brush, or by dipping, after which such articles or objects are introduced into a
muffle or oven, the heat of which is gradually raised to a sufficiently elevated
temperature, and they are taken out as soon as the muffle or oven is cool.
3. When it is required to obtain iridescence as well as lustre in the platinized
enamelled articles or objects, I employ in addition to platinum sulphurous or
metallic vapours or acid vapours in the following manner :-I grind with fatty
essence of lavender a quantity of chloride of platinum and German litharge, and
coat the enamelled articles or objects therewith, and when dry I place the articles
or objects so coated in a muffle or oven raised to an elevated temperature. As soon
as the articles or objects are found to have assumed a brilliant tint of silver or

page_text: polished steel I introduce some pure sulphur into the furnace, and after a short
interval I introduce a mixture of sulphur and an oxide of metal (according to the
tint required to be imparted to the platinized surface), say, for example, oxide of
copper. The sulphur and copper become volatilized, and the fumes proceeding
therefrom are allowed to enter the muffle or oven containing the articles or objects
under treatment so as to act upon the platinum and litharge coating, whereby
multicolored effects of iridescence are produced upon the articles or objects, which
In lieu of employing sulphur
may then be removed from the muffle or oven.
and a metallic oxide, the fumes of nitric acid or muriatic acid, or of the two
combined, may be used.
The furnace is separated from the muffle or oven by means of removable
registers for the facility of regulating the admission of the fumes employed, and
when nitric acid or muriatic acid is used the articles or objects are preferably placed
upon shelves in a passage through which a current of air flows, the acids being
caused to give off vapour by the application of heat, which is conducted
vapour
by the air current and brought into contact with the said articles or objects. It is
obvious that the derivatives of platinum, as, for example, palladium or one of its
derivatives, may be used in lieu of platinum itself.
4. In order to obtain a gilded effect gold may be employed in conjunction with
platinum in the following manner :—
The articles or objects are first coated with a platiniferous composition consisting
of chloride of platinum prepared in the manner herein described under the second
head of the present Invention.
The articles or objects are then baked in a muffle or oven, and after having been
withdrawn, are coated with a solution of gold, and are again baked.
By these means brilliant gilding is obtained without burnishing or polishing in a
most economical manner, platinum (or one of its derivatives, as, for example,
palladium or iridium) being used as a primal coating, and being followed by a
coating of gold held in suspension or in solution. The gold may be held in
solution or in suspension in essences or essential or other oils, sulphurous or non-
sulphurous. It may also be applied by means of volatile oils, ether, and the like.
My Invention is also applicable to platinizing and gilding vitrified or vitrifiable
products generally, such, for example, as porcelain, terra cotta, carthenware, pottery,
stoneware, crystal, glass, looking glasses, and the like.
5. When it is required to produce imitations of bronze upon metallic articles or
objects, I employ metallic powders or metallic leaves and oxides, which I apply to
the surfaces of such articles or objects, or I may apply to the said surfaces vitreous
substances capable of being acted upon by acids, gas, water, or air. For example,
I apply to the surface of the metals to be treated a coating of vitrifiable colors,
such as are employed for the decoration of porcelain, pottery, or glass, and then
sprinkle on a coating of metallic powder, which is caused to adhere by the appli-
cation of heat. All shades of color, from green bronze to gold bronze, and also the
imitation of old silver, may thus be obtained.
The bronzed articles or objects may, if required, be subjected to gilding, silvering,
platinizing, nickeling, or similar processes, by means of the battery or by simple
immersion.
In order that the said Invention may be perfectly understood, I shall now proceed
more particularly to describe the same, and in so doing shall give examples of the
methods of applying it to particular cases, from which examples those skilled in the
arts will be readily enabled to adapt it to any other cases which may occur in
practice.
1. In carrying out the process, which consists in applying alkaline and metallic
silicates in order to preserve inetals from oxidation, I proceed in the following
manner:
a. Alkaline Silicates.-
One part by weight of silica and three parts by weight of carbonate of potash
aut he weight of soda

page_text: the composition becomes yet inore fusible and penetrates more deeply into the
metal. After mixing the composition it is melted in a fire clay crucible by a strong
heat, and then poured out and ground up with spirits of turpentine or petroleum,
or other oils, the commonest qualities sufficing.
b. Metallic Silicates.-
One part by weight of silica and six parts by weight of red lead are mixed and
raised to a sufficiently elevated temperature to effect their fusion, after which the
product is poured out and ground up fine with any oil or essence thin or fatty;
spirits of turpentine and petroleum are used with advantage, being the cheapest.
In order to facilitate the working essence of Venice turpentine or fat oil of turps
may be added.
Mixtures of alkaline silicates with metallic silicates produce very satisfactory
results; moreover, the quantity of flux may be varied according to the temperature
which can be borne by the articles or objects to which the compositions are
applied.
The silicates of iron, copper, tin, manganese, barytes, bismuth, antimony, nickel,
uranium, chronium, cobalt, and the like may be used, but they change the colors
of the metals to which they are applied, although the results as regards inoxidation
are the same, especially if care be taken to thoroughly heat the articles by a strong
fire.
The silicate compounds having been reduced to a fine state of division and
thinned down to a convenient consistency, a very thin coat of the composition is
laid on the metal articles or objects which it is desired to render incapable of
becoming oxidized; the articles or objects are then introduced into a muffle or oven,
such, for example, as an enameller's or porcelain gilder's muffle, and the heat is
raised to, say, from 800 to 900 degrees Fahrenheit, or what is technically known as
cherry red; "the muffle is then allowed to cool, and the articles will be found
inoxidisable on their withdrawal.
"
2. The process hereinbefore referred to for imparting lustre to metallic surfaces is
applicable to wrought and cast iron, copper, and other metals, in a polished
state, capable of bearing a heat of 480 degrees, Fahrenheit, and to wrought and
cast iron, copper, and other metals coated with enamel or in their rough state.
In carrying out this process I pulverize 100 grammes (about 1543 grains troy)
of very pure crystallized chloride of platinum, which I introduce into a porcelain
capsule, and I place the latter on a sand bath sufficiently heated to dispel all
moisture from the chloride of platinum. I pour this powder when very dry upon
a glass slab; then I mix the powdered chloride of platinum with the least possible
quantity of the purest essence of lavender, gas is evolved. I grind the whole very
fine. I place the product in a porcelain capsule, and then I gradually pour
500 grammes (about 16 ounces apothecaries' weight) of liquid ammonia upon it.
A violent reaction takes place, I stir strongly for about thirty minutes, and
when the reaction has subsided and the product has become cool, I allow it to
stand for, say, about three hours, then pour upon the whole a quantity of very
warm distilled water. I pour off the water, which carries away the ammonia; I
repeat this operation until I have ascertained that no traces of the ammonia are 4
left. The platinum in this state is completely deprived of acid and will not oxidate
the metals on which it is applied. I dry up the few drops of water that may remain
and introduce the product into a glass stoppered bottle, and add 500 grammes (about
16 ounces apothecaries' weight) of rectified ether; the ether re-dissolves the platinum,
combined with the essence of lavender, and produces a liquid of a soft and agreeable 5
color; the application of this liquid to polished metals is very simple. I dip a brush
in the liquid and paint over the articles which I wish to platinize; then I place
them in a muffle, similar to that used by painters on porcelain, care being taken
more particularly to avoid exposure to dust. I close up the muffle, and I heat it
with a very slow fire to a temperature of 480 degrees Fahrenheit, which 5
temperature must not be exceeded. I allow the muffle to cool slowly, and then
draw out the articles, which will present the appearance of polished silver if

page_text: the coating has been laid on to a sufficient thickness. If the coating has been laid
on thinly, the tint is not so white and more nearly resembles polished steel. I may
recommence the operation and superpose coatings as many times as wished. Iron
or steel thus treated can be gilt or silvered by the galvanic or any other known
process.
In applying the system to wrought and cast iron and other metals when enamelled
it is necessary to add fluxes, which vary according to the enamel upon which the
platinum is intended to be applied.
Articles coated with the platiniferous preparation according to the said Invention
are very brilliant and of a more silvery white tone than has heretofore been
attained, whilst the effects produced are of a more permanent character than is the
case when platiniferous preparations containing acid are used.
3. In carrying out the process for obtaining iridescence on enamelled metallic
articles or objects, I proceed in the following manner :-
I take 50 grammes (about 1 ounce 12 pennyweights, troy), of chloride of platinum
or chloride of palladium, or of one of their derivatives, which I grind up with
7 grammes (about 4 pennyweights, troy) of German litharge on a glass slab
with a glass muller. I use in this grinding operation_300 grammes (about eleven
ounces, avoirdupois) of fatty essence of lavender. I then spread with a brush,
similar to the brushes used by house painters, a very thin coating over the articles
or objects which are to be treated, then I allow them to dry. I then place the
articles or objects so treated in an enameller's or other muffle, in which I have
taken care to arrange holes communicating with the furnace and closed by registers
opening at will. I watch the progress of transformation of the articles, and when
see them assume the brilliant tint of silver or polished steel, I open the registers
and I throw into the furnace some pure sulphur; then after a few minutes I also
throw into the furnace a mixture of sulphur and oxide of copper in about equal
proportions. The sulphur and the copper becoming volatilized, a portion of their
fumes passes through the registers and attacks the platinum which is in the act of
fixing itself upon the articles treated, and also combines with the litharge, and so
produces multi-colored effects of iridescence on the articles being taken out of the
oven. The addition of the copper to the sulphur produces a shot-shade of red and
purple, which it would be impossible to imitate by any known process.
quantity of sulphur employed will vary according to the fusibility of the enamel
used and the size of the muffle; about 1 lb. will generally be found sufficient for a
muffle of a capacity of, say, from 1 to 2 cubic yards. It will be evident that the
effects before mentioned are produced most economically and with great facility.
By employing other metals in place of copper, other tints can be obtained but at an
increased cost.
The
Enamels with a base of cobalt or of iron are those which give the most varied
and choicest shades. If the furnace be heated with coal it is always necessary to
take care not to open the registers until after the smoke has completely passed
away; firing with coke is always preferable.
I obtain almost analogous effects by exposing the platinized and baked articles
having the lustre of polished steel or polished silver to the fumes of nitric or
muriatic acid, or of the two combined. In order to obtain this result shelves are
fitted in a passage through which a current of air is caused to flow. At the end at
which the current enters there is arranged a brazier carrying a sandbath, on which
is placed a capsule containing either muriatic acid, nitric acid, or an equal mixture
0 of both. The brazier is slightly heated to drive off the vapour of the acids which
is carried into the passage, and into contact with the articles or objects which have
been placed upon the shelves. A few minutes generally suffices for the articles or
objects to become iridescent, but it is sometimes necessary to turn them, so that
they may receive the same quantity of vapour by means of the current of air on
5 both sides. The working is accelerated by throwing a few grains of tin into the
capsule from time to time.

page_text: 4. In carrying out the process of gilding upon enamelled articles or objects I
subject the latter to the operations next hereinafter described.
1st Operation. I take an article or object of enamelled iron (wrought, cast, or
sheet), copper, and the like, or of porcelain, earthenware, pottery, crystal, glass, or
any other ceramic material having a vitrified composition on its surface, then with
a brush I spread over the article or object on the places that are to be gilt a very
thin coating of platiniferous composition, consisting of chloride of platinum
prepared in the manner herein described under the 2nd head of the present
Invention.
I allow the articles or objects so treated to thoroughly dry (sheltering them from
dust), and I then bake them in a porcelain painter's muffle, which is heated
according to the fusibility of the enamels covering the articles operated upon.
I allow the muffle to become cool, draw its contents, and the articles which I have
coated with the platiniferous composition appear very brilliant. It is necessary to
wipe or dust them in order to proceed with the second operation, which produces
the gilding.
2nd Operation.-I dip a brush into a gold liquid or solution of gold and spread
an exceedingly thin coating of the same upon the places or parts already covered
with the platiniferous composition; I allow it to dry, and then return the articles
to the muffle, and bake them a second time. The substances entering into the
composition of the auriferous liquid are burnt up, and leave the gold in a metallic
state, of a fine yellow color, and very bright. The gold thus freed from these
foreign bodies fixes itself, and adheres to the platinum, and the two metals united
together form a very solid and very adherent coating, and also a very cheap one,
since the preliminary coating of platinum economizes the gold, which is only
required to be applied to the extent of a very thin coating. Sometimes it is
necessary to add fluxes either to the gold or to the platinum, the necessity for their
use being determined according to the fusibility of the enamels, or according to
the composition of the glasses or crystals, and their greater or less liability to lose
their shape in baking.
I may substitute for platinum one of its derivatives, such as palladium, iridium,
and the like, but platinum is preferable.
By means of this process I obtain brilliant gilding without burnishing by the
use of a preliminary coating of a cheaper material than gold followed by a coating
of gold held in suspension or in solution in fatty or essential bodies, sulphurous or
nonsulphurous, or heated by volatile oils or ether. The articles or objects to
which the process is applicable comprise iron wrought, cast, or sheet, and copper
coated with enamels varying in composition and color, as well as all other metals
capable of receiving a coating of vitrifiable composition; also terra cotta, earthen-
ware, stoneware, potteries, glass, crystal, looking glasses, mirrors, and the like.
5. In order to obtain imitations of bronze upon metallic articles or objects I
proceed in the following manner :—
For the production of green oxidized bronze I take green oxide of chromium,
such as is usually sold, prepared for painting on pottery or porcelain; I grind it
exceedingly fine with a glass slab and muller. This grinding is effected with spirits
of turpentine. When finished I add a twentieth part of its weight of white
turpentine varnish; I mix thoroughly then with the aid of a brush; I spread a
very thin coat over the articles or objects to be treated. It is then necessary to
allow the article or object to dry until it is slightly sticky on being touched, and
on its arriving at this condition I sprinkle it over with finely powdered copper.
I allow it to dry thoroughly, then I brush off the copper that has settled anywhere
too thickly; I then heat the article or object in an enameller's or other oven until
the vitrifiable color has become adherent to the metal, and in the course of
this operation the copper also sticks to the vitreous coating and becomes adherent
thereto.

page_text: In case one coating of copper should not suffice it will be necessary to repeat
the operation, making use of the same varnish thinned instead of colour.
When cooled the article should appear of a fine copper color, or sometimes black.
In this last case it is only necessary to dip it into acidulated water to restore the
metallic appearance; a potash bath often suffices.
If it be desired to produce the appearance of old bronze it is simply necessary
when once the article or object has passed through the bath to grease the projecting
parts, taking care not to touch the hollows, and to expose the article or object to
the action of the vapour of nitric acid, or to dip the article or object in a bath very
slightly acidulated with nitric acid, and then to allow the article or object to dry;
the hollows which have not been protected turn green, and the greased parts
remain of a metallic copper colour.
I can also obtain results producing almost the same effect by taking instead of
green oxide of chromium, rouge de capucine, employed in the same manner as
the green oxide, the coated article or object however being in this case passed into
the oven before the application of the metallic powder. After its removal from the
oven the article or object is allowed to cool, and I then spread thereon with a
brush a thin coat of varnish thinned down with a large quantity of spirits of
turpentine; then with a cloth I wipe the projecting parts, leaving the hollows
untouched. I allow the article to dry until the varnish is only slightly sticky, then
I sprinkle a coating of green oxide of copper or green oxide of chromium (the two
produce almost similar effects); then the hollow parts which have retained the
varnish absorb the green powders, and the projecting parts remain free from it,
through no longer having any varnish to hold it.
"
I slightly brush the article or object so as to remove any excess of oxide, then I
introduce the article or object again into the oven, but at a slightly lower
temperature; the oxides adhere, and on leaving the oven the articles or objects have
the desired appearance. I can obtain by these means all shades of color, that is to
say, that for each shade it is necessary to change the color; thus for yellow bronzes
I make the ground in "jaune d'argent ; for grecu bronzes, with green oxide of
chromium; for red bronzes with "rouge de capucine;" for Florentine bronzes, with
purples and carmines. I can thus by mixtures of color obtain all shades. For the
imitation of old silver I take a white or grey color according to the degree
of imitation of oxidation I wish to arrive at. The articles or objects treated with
metallic powders may be gilded, silvered, nickeled, platinised, or otherwise plated
by the battery or by simple dipping. Any known bath may be employed.
I may also employ metallic leaves, but I only use this system in cases in which
metallic powders cannot be applied.
I obtain imitations of oxidized metals less rich than by using the powders by
employing enamels, either colorless or tinted, with oxides, such as are used in glass
painting; these enamels or colors are readily fusible, therefore they should be
heated at a lower temperature, they all having for their base boric acid, lead, and a
very small quantity of silica. These enamels are readily acted upon by acids; I
employ them in the same manner as the powders. On leaving the oven and cooling
I plunge the articles or objects into a slightly acidulated bath; in some cases pure
water or water with some sea salt in it suffices. I allow them to remain in the
bath a few hours, then I remove them and allow them to dry, after which they are
covered with a dull dusty coating of the color of the enamel employed; I then rub
the projecting parts with a little grease, taking care not to touch the hollows. The
oxidation caused by the attack of the acidulated water is thus removed from the
projecting parts, whilst the hollows remain coated with it, the prominent parts
thereby becoming lustrous, and the hollows have a dull appearance, so that the
desired effect is produced.
If green enamel is employed the hollows are green, imitating oxidised copper,
whilst the projecting parts have the tint of bronze, rendered bright through having
been rubbed, and similarly with all the other shades.
The system of imitating bronzes lastly hereinbefore described is only employed

page_text: for the sake of economy in operating upon articles or objects of an inferior
character.
Having now described and particularly ascertained the nature of the said
Invention, and the manner in which the same is or may be used or carried into
effect, I would observe in conclusion, that what I consider to be novel and original,
and therefore claim as the Invention secured to me by the hereinbefore in part
recited Letters Patent is,-
First. The employment of alkaline silicates and metallic silicates, used either
alone or in conjunction, for the purpose of preserving metals from oxidation,
substantially as herein before described.
Secondly. The system or mode of imparting lustre to articles or objects of metals,
either polished or in a rough state or enamelled, by the application to such articles
or objects of platinum reduced by essential or other oils, purified, freed from its acids
by ammonia, and held in solution or suspension in rectified ether, alcohol, or spirits,
the solution being applied direct to the surface of such articles or objects,
substantially as herein before described.
Thirdly. Obtaining multi-colored iridescence upon the surface of metals covered
with a coating of enamel by the employment of platinum or palladium, or one of
their derivatives, in conjunction with sulphurous and metallic vapours or acid
vapours, substantially as herein before described.
Fourthly. The employment of platinum, or the derivatives of platinum, and
gold superposed one over the other for the purpose of gilding articles, or objects,
substantially as herein before described.
Fifthly. The production of imitations of bronze upon metallic articles or objects
by the employment of metallic powders, or metallic leaves and oxides, or of
vitreous matters, applied either without color or with the addition of coloring
oxides, all substantially as hereinbefore described.
In witness whereof, I, the said John Henry Johnson, have to this my
Specification set my hand and seal, this Eighth day of February, One
thousand eight hundred and eighty one.