IMPROVEMENTS IN THE MANUFACTURE OF COLORS AND PAINTS
Year: 1853

page_text: LETTERS PATENT to William Clark, of 31, Chancery Lane, in the
"
"County of Middlesex, Patent Agent, for the Invention of
"IMPROVEMENTS IN THE MANUFACTURE OF COLORS AND PAINTS."—A
communication.
Sealed the 12th August 1853, and dated the 15th February 1853.
PROVISIONAL SPECIFICATION left by the said William Clark at
the Office of the Commissioners of Patents, with his Petition,
on the 15th February 1853.
I, WILLIAM CLARK, of 31, Chancery Lane, Patent Agent, do hereby
6 declare the nature of the said Invention for "IMPROVEMENTS, IN THE
MANUFACTURE OF COLOURS & PAINTS" (being a communication from a
foreigner residing abroad) to be as follows: -
The Invention communicated to me refers to the combination of
materials whereby I am enabled to produce paints and colours of a
Opermanent character being unaffected by the atmosphere or noxious
gases, by which ordinary paints & colours are attacked.
I employ oxide of zinc, for the most part, as a basis, which I com-
bine with other matters according to the colour to be produced; as

page_text: for instance, for the manufacture of chrome yellow, I use a solution
of bichromate of potash, sulphuric acid, and zinc white. The zine
combines with a certain quantity of the other matters, and forms a
precipitate, which properly treated is applicable as a paint.
To produce the same of a lighter tint, I use the supernatant liquid
from the above, and reduce it by evaporation. I then subject zinc
white to its action by immersion as before. Paler colours will result
by the further use of the same liquid as described.
To produce citron or lemon colour, I dissolve the zinc white in
nitric acid & sulphuric acid, and precipitate the result in a solution 1
of bichromate of potash.
I obtain orange colour, by uniting the sulphuret of antimony
with hydrochloric acid, which I then precipitate in a solution of sul-
phuret of iron and sulphuric acid.
To produce cadmium yellow, I dissolve cadmium in nitric acid, 1
and precipitate the result in a solution of sulphureted hydrogen.
To produce blues, I obtain an extract of cobalt by dissolving that
metal in nitric acid, the result of which I precipitate in a solution
of zinc white.
To produce greens, I take the oxide of cobalt, and attack it by 2
sulphuric acid. When reduced by this means, I then burn it in a
crucible, and afterwards dissolve the result in hot water. Zinc white
is then to be mixed with the solution till of a pasty consistence, and
the whole burnt in a retort.
These colours are applicable for the production of other colours, 2
by mixture as well understood, and also with the further addition of
zinc white and other mineral substances.
These colours are mixed with oils, & applied in the manner of
ordinary paints, and are also applicable for other coloring purposes.

page_text: SPECIFICATION in pursuance of the conditions of the Letters
Patent, filed by the said William Clark in the Great Seal
. Patent Office on the 15th August 1853.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I,
WILLIAM CLARK, of 53, Chancery Lane, in the County of Middlesex,
Patent Agent, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by
Her Letters l'atent, bearing date the Fifteenth day of February,
in the year of our Lord One thousand eight hundred and fifty-
three, in the sixteenth year of Her reign, did, for Herself, Her heirs
and successors, give and grant unto me, the said William Clark,
Her special licence that I, the said William Clark, my executors,
administrators, and assigns, or such others as I, the said William
Clark, my executors, administrators, and assigns, should at any
time agree with, and no others, from time to time and at all times
thereafter during the term therein expressed, should and lawfully
might make, use, exercise, and vend, within the United Kingdom of
Great Britain and Ireland, the Channel Islands, and Isle of Man, an
Invention for "IMPROVEMENTS IN THE MANUFACTURE OF COLORS AND
PAINTS,"
upon the condition (amongst others) that I, the said William
Clark, by an instrument in writing under my hand and seal,
should particularly describe and ascertain the nature of the said
Invention, and in what manner the same was to be performed, and
cause the same to be filed in the Great Seal Patent Office within six
calendar months next and immediately after the date of the said
Letters Patent.
NOW KNOW YE, that I, the said William Clark, do hereby
declare the nature of the Invention communicated to me, and in
what manner the same is to be performed, to be particularly de-
scribed and ascertained in and by the following statement thereof;
reference being had to the Sheet of Drawings hereunto annexed, and
to the letters and figures marked thereon (that is to say):
The Invention communicated to me consists of a new manufacture
of colors and paints, whereby I am enabled to produce colors and

page_text: paints in colors of a more permanent character than heretofore,
being comparatively unaffected by the atmosphere or gases by which
ordinary paints in colours and colours are attached..
The colours which I manufacture are applicable as paints when
mixed with oil and other necessary ingredients, and in others as
colouring matter for paints, also for dyeing, paper staining, and other
like purposes. In this manufacture of colours, oxide of zinc is for
the most part employed as a basis, which is combined and treated
with other materials according to the colour to be produced, as will
be understood by the following description of the several colours
manufactured.
Dark chrome. One hundred and twelve pounds of bichromate of
potass is placed in a copper over a suitable furnace, and, by the
application of heat, melted and brought to the boiling point.
Seventy pounds of the oxide of zinc is then mixed with thirty-five
gallons of water in a separate vessel, and when thoroughly mixed is
poured into the copper containing the bichromate of potass. The
whole is now boiled, the boiling being continued during one hour,
stirring and mixing the whole intimately together. I now separate
the heavier part or colouring matter from the solution, which is
effected by precipitation in a vessel to which I now remove the con⚫
tents of the copper. For this purpose, I use a deep wooden tub, in
which there are a number of spigot holes at different elevations.
The contents of the copper being placed in this tub, and allowed to
stand some time, the colouring matter precipitates from the solution.
The upper spigot hole is then opened, and the supernatant liquor
allowed to run off; subsequently a lower hole is opened, and a
further portion of the liquor allowed to run off, and so on until all
the supernatant liquor is drawn off, and a colouring matter of a
Clean water is
pasty consistency remains in the bottom of the tub.
then to be put in the tub, in order to wash the colouring matter,
stirring the whole intimately together in order to remove any trace
of the acid that may remain therein. The colouring matter is again
allowed to precipitate, and the supernatant liquor allowed to run off
as before.
This washing is repeated until the whole of the acid is

page_text: removed. The chrome or colouring matter thus obtained is now
to be dessicated, for which purpose it is removed from the tub, and
divided into small masses disposed on suitable shelves or trays per-
forated, or of open basket work, in a drying room heated to about
one hundred degrees Fahrenheit, where it is allowed to remain
until all the moisture is dispelled, when it is fit for use.
When chromes of lighter shade are required, it is necessary to
use a greater proportion of oxide of zinc. For the lightest shades of
colour I use about one hundred and thirty pounds of oxide of zinc.
to one hundred and twelve pounds of bichromate of potass, and for
medium shades a suitable quantity of those materials, proceeding in
a precisely similar manner as before. A quantity of water, in pro-
portion to the additional quantity of oxide of zinc, is to be used in
manufacturing the lighter shades of chrome.
For the manufacture of citron or lemon colour pigments, I use the
liquor derived from the manufacture of chrome and separated from
that pigment, when precipitated as before described. This, together
with the liquor resulting from washing it, are placed in a suitable
copper, and reduced by boiling till the specific gravity is twenty-five
degrees of the ordinary acid Hydrometer. For every eight gallons
of the liquor so reduced dissolve forty pounds of oxide of zinc in
twenty-four pounds of sulphuric acid. This mixture of oxide of
zinc and sulphuric acid is placed in the copper containing the liquor,
with which it is intimately mixed by stirring, and the whole boiled"
together for the space of one hour. The contents of the copper is
now removed, and placed in a tub havings pigot holes as before de-
scribed, and in which the pigment or colouring matter is allowed to
precipitate, and from which the supernatant liquor is drawn off as
before explained. The colouring matter is also washed by adding
clean water to it in the precipitating tub, and drawing it off, which
is repeated until all trace of the acid is removed. The colouring
matter so obtained is now placed in small masses on the shelves or
trays of the drying room, where the moisture is dispelled as explained
with reference to the chrome.
In the manufacture of cadmium yellow, I take half a pound of

page_text: cadmium, and cut it up in small pieces, and place it on a capsule
with a pint of water. The capsule is placed in a hot sand bath, and
kept at a temperature just below boiling point. In order to dis-
solve the metal, I mix nitric acid with the water, adding a few
drops at a time so as to maintain a uniform action on the metal,
which will be readily observed by the gases formed by its decompo-
sition. The quantity of acid required to dissolve the metal will be
about seven ounces. The liquor resulting, which contains the cad-
mium in solution, is now diluted and treated with sulphuretted
hydrogen gas. For this purpose I dilute the solution of cadmium,
which will measure about a pint, with two gallons of water, and
place it in a Woulffe's bottle, or, in order to economise the gas,
in
two such bottles, and cause the same gas to circulate through both
as represented at Fig. 1, in the Drawing annexed. The vessel A,
is that in which the gas is generated by the decomposition of the
sulphur of iron by sulphuric acid, which is added slowly from this
vessel. The gas is conducted by a pipe B, into the bottle C, in which
the liquid to be operated upon is placed & passed and down through
that liquid is suffered to escape therein at the bottom, the gas
disperses and quickly rises through the liquid, on which it acts
chemically and produces a change of colour. The passage of the
gas keeps up a constant ebulition or motion in the fluid, and
assists to hold the colouring matter in suspension. The gas is
conducted from the first vessel C, to a second D, containing the
same kind of solution, on which it takes a similar effect, and after
rising up through the contents of the second bottle D, it is
carried off by the pipe E, and conducted through lime water in
the vessel F, in order to prevent the noxious smell of the gas. The
solution when placed in the bottles is colourless, but by the action
of the gas on the matters held in solution, it changes to that of a
cadmium yellow, the action of the gas being continued until the
colour becomes of the proper hue. Having subjected the solution
to the action of the gas a sufficient length of time, it is allowed to
settle, when the precipitation of the colouring matter takes place.
The supernatant liquor is poured off, when the colouring matter

page_text: may now be removed, and is subsequently dried in small masses in
the trays or shelves of the drying room as before explained.
Should the liquor drawn off contain metal, I again subject it to the
action of the gas as before, in order to convert the colouring matter.
as desired, which is precipitated and treated as before.
For cadmium yellow of a lighter shade, a small quantity of oxide
of zinc is mixed with the dilute solution before treating it with the
gas. For this purpose the oxide of zinc is dissolved in sulphuric
acid, using for the foregoing proportions half a pound of oxide of
zinc to one ounce of sulphuric acid. This is intimately mixed
with the dilute solution before placing it in the bottles to be treated
with the gas. The colour may be produced in different hues by
varying the proportion of oxide of zinc mixed with the solution for
that purpose.
In the manufacture of red and orange colours, I place a quart of
muriatic acid in a Madras or suitable bottle, heat the same in a
sand bath, and dissolve in it one pound of sulphur of antimony.
The bottle or vessel containing the antimony and acid is kept in
the sand bath so long as any of the metal remains undissolved.
Should ebulition discontinue before the metal is entirely decomposed,
I add more acid in order to completely effect that object. This
process will occupy about two hours. I afterwards filter the result
in an ordinary chemical filter of paper. Half a pint of the solu-
tion is to be diluted by the addition of one gallon of water, when
it is to be placed in the Woolf's bottle represented in Fig. 1, of the
Drawings, and treated with sulphuretted hydrogen as before de-
scribed with reference to cadmium. The chemical action of the
gas upon the matters held in solution produces a change of colour
in the fluid, which assumes a reddish hue. Having been subjected
to the action of the gas a sufficient length of time to affect.
the desired change of colour, the colouring is suffered to deposit,
and the supernatant liquor is drawn off. The colouring matter
thus produced is now removed and subjected to the action of the
drying rooms to dispel the moisture and render it fit for storing.
The colour so produced will be a bright red, and by the mixture of

page_text: certain proportions of oxide of zinc therewith the various shades
of orange colors inay be produced. This will not require any
particular description. The larger proportions of oxide of zinc will
of course produce the lightest shades.
In order to produce blues, I take half a pound of the metal
cobalt, and place it in a capsule with a pint of water, and heat it in
a sand bath. In order to decompose the metal and form a solution,
I introduce nitric acid in small quantities while it is in the sand
bath. The acid attacks the metal, and continuing to add a few
drops of the acid at a time the metal will be entirely decomposed.
To the solution thus formed a quantity of oxide of zinc is to be
added, using two pounds of oxide of zinc to a pint of the solution.
This is mixed intimately together, and is of a pasty consistence.
The mixture is submitted to the action of a furnace in a crucible in
which it is subjected to high heat in order to calcine it. The
colouring matter thus produced will be in a state of powder, and
suitable for use.
.
To manufacture green colors, I place two and a half pounds of
sulphuric acid in a capsule, and stir in gently one pound of oxide
of cobalt. The capsule is now to be placed in a hot sand bath,
heating the contents gradually. The action of the heat is con-
tinued until the cobalt becomes of a red color. The contents of
the capsule must be continually stirred the whole time. It will
require about three hours' immersion in the sand bath for the
pur-
pose of converting the cobalt into the required state, which will
be indicated by the color it assumes being of a redish hue.
About a pint of the solution will remain in the capsule, which is`
now placed in a crucible, and subjected to the action of a furnace in
order to evaporate the acid, which will occupy about an hour. I
now take the cobalt from the crucible, and dissolve it in twenty
gallons of water in a suitable wooden vessel, and subsequently mix
with it thirty pounds of oxide of zinc, stirring the mass quickly,
when it will assume a pasty consistency. This mixture of oxide of
zinc and cobalt is then placed in a retort, and at first heated gra-
dually to dispel the moisture. Figure 2, is a front elevation of the

page_text: retort furnace; Figure 3, a transverse vertical section; and Figure 4,
a longitudinal vertical section of the same. A, is the fire place;
which is built of or lined with fire clay lumps. The fireplace is
covered with a slab B, of fire clay, on which the retort C, is placed
and rests. Openings D, D, are formed at the back part of the
fireplace up into the chamber containing the retort for the passage
of the heat and flame. The chamber of the retort is covered in by:
another fire lump E; and openings F, F, are formed at the front
end of the chamber into an upper chamber G, which leads to the
chimney. Plates or covers: H, H, are placed over the openings
D, D, to protect the retort from the direct play of the heat and
flame. The retort chamber is divided by a diaphragm L, which
separates the front end from the chamber containing the body of
the retort. This is enclosed by a suitable door I, which is left open
when the contents of the retort are first subject to the heat of the
fire. The opening K, in the retort is also left open. The mixture;
of cobalt and oxide of zinc, treated as before described, is intro-.
duced into the retort, and the action of the furnace commenced.
A slow heat is at first applied, which evaporates the moisture.
This is continued until all moisture disappears, when the door I, in
front of the retort, is closed, and the heat of the fire augmented,
the action of which is continued until the desired result is obtained.
The heat of the fire taking effect on the fire lump or slab B,
prevents any sudden or. injurious heat taking effect on the retort...
The heat and flame passing up through the openings D, D, and tra-
versing the full length of the retort, ascends to the upper chamber
G, which it also traverses, and passes thence to the chimney. The
retort is thus surrounded by and subject to the action of the heat
on all sides, by which it is brought to a white heat. The door I,
and the hole in the retort, is occasionally opened for the purpose of
testing the progress of the operation, which is known by the shades
of color it assumes under the continued action of the heat. The
proportions of materials before given will produce a green of a
certain hue, at which it arrives by the action of the heat in the
retort. The process is watched and tested by withdrawing a

page_text: portion of the contents of the retort from time to time, and when
it arrives at the proper shade of color the operation is suspended,
and the contents of the retort removed. In this example the result
will be of a dark color, which depends on the quantity of oxide of
zinc mixed with the solution of oxide of cobalt. For lighter
colours a greater proportion of oxide of zinc is employed, which
may be increased to about eighty pounds weight of that material
to the foregoing proportion of oxide of cobalt.
All these colors are adapted either for oil painting, for dying,
paper staining, or other purposes, in all of which they are used in
the ordinary manner of other colors. For oil painting care should
be taken that the oil is pure as possible, and that other matters
affected by the action of the atmosphere are not mixed therewith.
Such mineral substances as terra cassel, terra sienna, or umber may
be added without any ill effects; oxide of zinc may also be added
at any subsequent stage, to vary the shade, or as an admixture for
any other purpose.
In witness whereof, I, the said William Clark, have here-
unto set my hand and seal, the Fifteenth day of August, in
the year of our Lord One thousand eight hundred and fifty-
three.
WILLIAM CLARK. (L.S.)