IMPROVEMENTS IN PREPARING AND COMBINING METALLIC SUBSTANCES FOR THE PRODUCTION OF COLORS, AND IN MANUFACTURING THE SAME
Year: 1856

page_text: LETTERS PATENT to Charles Sylvester Rostaing, of Dresden, in the
Kingdom of Saxony, for the Invention of "IMPROVEMENTS IN PREPARING
AND COMBINING METALLIC SUBSTANCES FOR THE PRODUCTION OF COLORS, AND IN
MANUFACTURING THE SAME."
Sealed the 24th February 1857, and dated the 26th December 1856.
COMPLETE SPECIFICATION filed by the said Charles Sylvester Rostaing
at the Office of the Commissioners of Patents, with his Petition and
Declaration, on the 26th December 1856, pursuant to the 9th section
of the Patent Law Amendment Act, 1852.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, CHARLES
SYLVESTER ROSTAING, of Dresden, in the Kingdom of Saxony, send greeting.
WHEREAS I am in possession of an Invention for "IMPROVEMENTS IN
PREPARING AND COMBINING METALLIC SUBSTANCES FOR THE PRODUCTION OF COLORS,
AND IN MANUFACTURING THE SAME," and have petitioned Her Majesty to grant
unto me, my executors, administrators, and assigns, Her Royal Letters
Patent for the same, and have made solemn declaration that I verily believe
myself to be the true and first Inventor thereof:
NOW KNOW YE, that I, the said Charles Sylvester Rostaing, do hereby
declare that the following Complete Specification, under my hand and seal,
fully describes and ascertains the nature of my said Invention, and the manner
in which the same is to be performed, reference being had to the accompany-
ing Drawings.
My Invention consists in the production of unalterable and non-poisonous

page_text: colors, applicable to painting in oils, water colors, fresco painting, a l'aquarelle,
wax, chloride of zinc, size, or glue, caseate of lime, silicate of soda and of
potassa (soluble glass); which colors are also applicable to printing by
rollers of carpets and colored papers.
These colors have over all others the following advantages: they possess
no poisonous or other properties dangerous to health, as do the greens, yellows,
and most of tl.e oranges and browns in use at present, which are composed in
part of arsenic, copper, arsenite of copper, oxide of lead, chromate of lead,
chromate of copper, and the like, either in their manufacture or use, being
entirely composed of mineral substances almost inert. Their manufacture or
composition is neither difficult or complicated, and, as regards all colors,
exceedingly economical. The divers shades of color are easily obtained by
arranging (by increase or diminution) the proportion of coloring oxides. These
pigments are perfectly unalterable; they may be brought to a red heat, and
after cooling will regain their primitive colors. They are not affected or
changed by the action of hydrogen, sulphuretted or carbonated gas, or other
gases or emanations peculiar to all populous cities. They mostly possess all the
properties and advantages of ordinaryoxide of zinc, and the generalityofthem
coat better and dry faster than zinc white. These colors may be used mixed in
oil or water for fresco,aquarelle, or wax painting, or with chloride of zinc, size,
or glue, caseate of lime, silicate of soda and of potassa (soluble glass); as also
in cylinder printing upon cloth, cotton, or other textile fabrics, such as paper
rolls or carpets, the impression upon woollen cloths or carpets, the manu-
facture of printed and colored papers, and, in short, to every description of
painting or coloring. They may be used in combination with carbonate of
lime, sulphate of barytes, argile. or dead or inert plaster, without any particular
loss of their properties. These colors dry very rapidly, become very hard,
and when used with white or other drying oil appear like enamel. They
harden very quickly when kneaded or mixed with drying oils in the pro-
duction of mastich, colored stuccos, cements, or other plaster.
To dispense with the use of oils in painting with these colors they are
prepared in the following manner:-They are diluted or thinned by a solution
more or less concentrated of a salts of zinc, (the chloride is the best), and the
concentration ofthesolution will depend entirely uponthelength of timeallowed
for drying the colors. Thus, if they are diluted with a solution of the strength
of fifty-five degrees, "Baumé's areometer," they dry immediately; but when it
is desired to paint with these colors, the solution of chloride of zinc must not
be of greater strength than thirty degrees "Baumé," and to prevent their
hardening too quickly three per cent. of borax or of salammoniac are added.

page_text: It is only when making colored marbles and stuccos that a solution of fifty-
five degrees "Baumé" should be used. The proportions in the composition
of colored marbles and stuccos for mosaic and other purposes, is about two
parts of coloring matter or paint to one part of chloride of fifty-five degrees
"Baumé," which are well mixed together and then run into moulds of
any desirable form or shape. To render these marbles and stuccos harder
and more brilliant they are soaked with drying oils.
The chloride of zinc employed for the above-mentioned purpose is prepared
by dissolving thoroughly burnt blende in the hydrochloric acid of commerce
(muriatic acid)until entire saturation,diluting it with rain water to a strength
of fifty-five degrees "Baumé," and for painting as low as thirty degrees
"Beaumé." Other metallic chlorides may be substituted in lieu of the
chloride of zinc, such as the chlorides of manganese, iron, cobalt, nickel,
and other, and even by the hydrochloric acid of commerce.
To paint without oil, these colors may also be mixed with glue water, to
which is added a small quantity of chloride of sodium (common salt), in the
proportion of one part of chloride of sodium to one hundred parts of dry color;
and the object to be colored receives as many coats as desirable, and when
perfectly dry should be varnished several times with one or other of the follow-
ing preparations, (that is to say): firstly, six parts of stearic acid, four parts
of wax, four parts of colophony, and one part of tannin; secondly, ten parts of
stearic acid and five parts of colophony; these are dissolved in one hundred
parts of warm alcohol, or in rectified oil of turpentine; or a varnish composed
of stearic acid and alcohol may be used, which when dry must be well rubbed
with a hair brush to give it the brightness of a varnish. The painted surface
may also be damped with a solution of chloride of zinc, of thirty degrees
"Baumé," and afterwards varnished. Colors prepared in this manner give
the appearance of polished marble, and will remain intact for an indefinite
period.
In caseate of lime painting the colors ground with water or oil are mixed
with the caseine and lime solution, and the paint is put on as in oil painting.
The preparation of the caseate of lime that I employ for this purpose is
as follows, (that is to say, one part of caseine or white cheese is boiled during a
quarter of an hour with four parts of spring water in a cast-iron or copper pot,
the contents of the pot are then thrown into a fine sieve and allowed to drain,
washed with cold water; what is left in the sieve is then pressed into a linen
bag to extract a part of the water; this caseine is then weighed, and one
quarter of its weight of good quick lime (extinguished by the addition of eight
times its weight of water, making a milk of lime,) is added thereto, and this

page_text: thick liquid is then bottled, corked, and left to itself. After some time it gives
an ammoniacal odour and liquifies itself, taking the consistency of oil; when
it has arrived at this state it is mixed with the colors, either dry or ground
with oil or water, and may be used as other paints. This description of
painting has the advantage of being inodorous, and of drying in the space
of an hour or two; a light coating of drying oil may then be put on as a varnish,
but this is not always necessary. To paint with these colors, employing
soluble glass, the same process is followed as with ordinary colors.
Textile fabrics are printed in the following manner:-The colors are mixed
with a solution of chloride of zinc, of from twenty-five to thirty degrees
"Baumé," adding thereto one and a half per cent. in weight of salammoniac
or of borax, that the paste may remain a long while in a liquid state; the
desired pattern or design is then printed on the cloth or paper and allowed to
dry. Colors thus employed resist the action of water, and are insoluble;
but if they are much rubbed together when wet the color comes off by degrees.
The printing may also be done in the following manner:-The colors are
ground with a sufficiency of oil, (linseed or any other drying oil may be used,)
and enough white Marseilles soap dissolved in warm water is added to cause
the color ground in oil to mix freely with the water; to this is added
one-twentieth of the weight of the ground color of hydrate of alumina,
obtained by the precipitation of the alum of commerce by ammonia or alcalis,
and washing the residuum with water before using it. Colors printed when
thus prepared do not harden, always remaining supple and pliable. This
preparation is also very useful in decorative painting, and for wall or
colored papers.
To prepare pigments for coloring paper it is only necessary to grind them
in an ordinary color mill, with the necessary quantity of yellow wax and white
soap, in the usual manner. The general use of these colors will have the
effect of completely banishing those composed in part of arsenic, copper,
or other poisonous substances, and the painters' colic, dry gripes, and other
diseases which they produce, will become less frequent.
Preparation and Composition.-Oxide of zinc, obtained from no matter
with mineral, forms the foundation of my colors; and I have chosen blende
or native sulphuret of zinc from which to obtain this oxide more or less
pure, as it is more economical by reason of its secondary production (sulphuric
acid) than any other zinc ore. The operation of roasting blende in order
to obtain sulphate of zinc is well known in metallurgy, and gave me the
first idea of these colors, upon which I have based my process. The
process I employ in the preparation of these colors is based upon the pro-

page_text: perty possessed by blende or native sulphuret of zinc of changing into
oxide more or less pure, and in its amorpheous state losing its sulphur
when submitted to a proper roasting operated in contact with air in rever-
beratory furnaces. The oxide of zinc which remains is ordinarily diversely
colored by the oxides which were combined with the blende before the
roasting process in the state of sulphurets. The different varieties of blende
themselves give colors when properly roasted without the addition of coloring
oxides. Thus, the white and yellow varieties of sulphuret give a coloralmost
as white as ordinary oxide of zinc, the yellow and grey yellow variety give
very clear yellows, the greenish yellow produces a color nearly approximating
a very clear greenish grey, the red variety gives ordinarily a very clear yellow,
and the black and brown varieties produce deep or lighter shades of brown.
To prepare these colors from blende alone it is first culled or picked, that is
to say, the different shades are separated, and having been washed (supposing
them to be soiled by earth or other impurity) they are reduced to a powder,
fine as flour, by a mill or otherwise. This powder is placed in a suitable re-
ceptacle, and sprinkled with one hundredth part of its weight of azotic acid
or sulphuric acid diluted by from twice to four times its weight of water, the
whole being carefully and exactly mixed; or the sulphate of zinc of commerce
may be advantageously substituted for the acids, added in the proportion of
four pounds to every one hundred pounds weight of brute blende, and then
ground to powder in a mill. These mixtures or compositions are then placed
in the reverberatory furnace (previously heated) and spread upon its bottom
in a layer of about two inches thick. The acids or sulphate of zinc are added
for the purpose of oxidizing a portion of the sulphur contained in the blende,
and to accelerate the roasting process. If it be desired still further to vary
the shades, sulphate of alumina is added instead of the acids or sulphate of
zinc,in proportions varied according to the shade of color desired. The heat
of the furnace is increased, and as soon as the matter or preparation has
become red hot it is brazed or stirred over every twenty minutes with iron
pokers or bars in order to renew its surface. When all the ore has attained
a white heat, and the whole of the sulphurous acid is disengaged, it is kept in
that state for half an hour, in order to develop the color in its greatest
intensity, it is then withdrawn by the openings H, H, (see Drawing), from
whence it falls by the conduits I, I, into the lower reservoir or receiver U,
where it cools. When it is sufficiently cold it is ground in a color mill (with
excentric millstones with riverwater until reduced into an impalpable powder.
This color upon leaving the mill is dried and packed in the same manner as
zinc white. The different blendes treated in this manner produce extremely

page_text: cheap colors, very useful in house and decorative painting. The first charge
of color being withdrawn from the furnace, it is replaced by a second, which
may weigh about sixteen hundredweight, and the roasting is recommended
The following changes are consequent upon the roasting of the blende:-The
acid or sulphate that is added acidifies a portion of the sulphur, the sulphuret
becomes red hot from its contact with an excess of overheated or burnt air
which escapes by the muffles 01, O', (Figure 1 of the Drawing), and com-
bining with the sulphur produces sulphurous acid, which, with the excess of
atmospheric air, disengages itself by the chimney F¹, and on its passage passes
over the pumice stones spread at the bottom or back of the chimney, and
which are at a dull red heat, and from thence into the condensing chamber G
to deposit the particles that it may have carried with it or volatilized. The
gases on leaving the condensing chamber are conducted into one or other of
the leaden or brick chambers, coated interiorly with the sandstone of which
stone ware is manufactured, in order to obtain an acid freed from lead to be
transmuted into sulphuric acid by the usual and well-known means. The
pieces and balls of pumicestone in the back and part B of the chimney are for
the purpose of effecting the combination of part of the atmospheric air by
contact with the sulphurous acid, and forming from the vapour thereof sul-
phuric acid, thus effecting a great economy of the azotic acid employed in
the fabrication of sulphuric acid. Another portion of the oxygen of the hot
air escaping by the muffles 01, 0, combines with the residue of zinc in pro-
portion as the sulphur acidifies itself, producing amorpheous oxide of zinc
colored by the diflerent metallic oxides that were contained in the blende
in the state of sulphurets. To make all sorts of color imitating the native
ochres, chrome, Naples, and other yellows, greens of every shade, greys and
browns, violet brown, reddish brown, and others, the oxide of zinc from the
blende is colored with metallic oxides, such as oxide of iron, peroxide of
manganese, or the oxides of cobalt, nickel, copper, chromium, or iranium,
and the shade of color varied by the addition of oxide of aluminium or
alumina. I employ the oxides simply in the state of salts, such as nitrates,
sulphates, and chlorures, and in the state of sulphurs. The oxides that may
be used pure are those of nickel, cobalt, copper, and manganese, pure native
sulphuret or bisulphuret of iron, sulphuret of cobalt, or sulphuret of nickel;
the other sulphurets give bad results, as they are melted by heat, and cause
the mass to conglomerate, which should be above all things avoided. Sul-
phuret of copper may however be used, care being taken to regulate the heat
during a certain time to prevent the fritting of the mass; the heat may
afterwards be increased as with the other colors.

page_text: To make colors imitating the native ochres, and to produce a variety of
colors as yet non-existant. The oxide of zinc from the blende is colored as
follows:-Crystallized sulphate of iron is mixed with the pieces of blende in
proportions varying from four or five pounds to forty-five pounds per hundred
and twenty-five pounds weight of brute blende, according to the shade of color
desired; they are then ground together in a mill, and being introduced into
the reverberatory furnace, herein-after described, they are roasted, in order to
decompose the mixture and effect the combination of the oxides. It is more
advantageous and economical to substitute in lieu of the crystallized sulphate of
iron pure native bisulphuret of iron, but much less must be added. For example,
instead of four or five pounds, half the quantity only of bisulphuret is to be
used; and, further, it is necessary to sprinkle the mixture with a one-
hundredth part of azotic acid(nitric acid),sulphuric or hydrochloric(muriatic
acid), diluted by twice their weight of water; or for these acids may be sub-
stituted about five pounds of the sulphate of zinc of commerce. When it
may be desired further to vary the shades, the acids and sulphate of zinc are
replaced by eight or ten pounds of crystallized sulphate of alumina, and the
proportion of this sulphate may be increased to about one hundred and seventy
pounds for every two hundred and seventy-four pounds of blen le, which will
give ten per cent. of alumina or oxide of aluminium. When large quantities
of sulphate of alumina are used it should first be partly dishydrated. When
the color has be sufficiently baked it is withdrawn by the openings of the
furnace, and when cool is waterground in an excentric mill. By the addition
of other oxides to the iron the shades are varied at pleasure. Manganese
gives yellows and brownish yellows of every shade, in obtaining which I use
the manganese in the state of salts, sulphate, or chlorure of sulphuret, or
crystallized peroxide. The salts or sulphuret is mixed with the blende, and
the operation proceeds as for the pigments colored by iron; the proportions
vary from seven drachms, which gives a very clear yellow, to twenty-six
pounds of peroxide for every two hundred and seventy-four pounds of blende,
which gives the deepest brown yellow. When crystallized peroxide of man.
ganese is used, it is thoroughly mixed with the blende, and sprinkled with
chlorhydric or sulphuric acid diluted by about twice their weight of water.
The proportion of acid added should be two parts of concentrated acid diluted
by twice its weight of water to one of crystallized peroxide. Cobalt gives
pure greens of every shade; the nitrate, chlorure or sulphate, sulphuret or
oxide, are used. One only of the salts, the sulphurets or the oxides, is mixed
with the blende, in proportions varied according to the shade required, from
eight ounces to six or eight pounds of oxide to every two hundred and

page_text: seventy-four pounds of blende, the same process ensuing as with the colors
produced by iron. The shades of green are varied and more brilliancy
given by adding to the blend before roasting from ten to about one
hundred and sixty pounds of crystallized sulphate of alumina, obtaining a
blue green, or a much less quantity of dishydrated sulphate of alumina(which
contains the same quantity of oxide of aluminium or alumina), and they are
burnt together until the whole of the sulphuric acid is disengaged, and it is
retained at a white heat for an additional half hour, that the color may develop
it its greatest intensity. In preparing the oxide or the sulphate of cobalt
used in producing these greens I adopt the following economical process :-
The cobalt ore (previously burnt and reduced into a fine powder as it may be
bought from almost every mine) is mixed with fifteen per cent. of its own
weight of dishydrated soda (ordinary soda without crystal water) and one per
cent. of its weight of nitrate of soda(azotate of soda). These mixtures are then
placed in the reverberatory furnace and made red hot in contact with the air;
the red mass is withdrawn from the furnace and diluted with water,dissolving
the arsenite of soda, which may be gathered by evaporating the solution. (The
residuum, composed principally of oxide of cobalt free of arsenic, is dissolved
in diluted sulfuric acid by means of steam heat.) This operation may take
place in enamelled cast iron or leaden boilers heated by steam. When the
acid has nothing more to dissolve, the solution is allowed to settle and clarify,
and is then decanted into another boiler and crushed, white marble or chalk is
added; it is then boiled for several minutes in order to precipitate the iron.
This solution when clarified is emptied into flat leaden vessels and evaporated
to obtain the crystallized sulphate, which is added to and thoroughly mixed
with the blende. Should the ore contain traces of nickle, copper, bismuth,
antimony, or other,a current of sulphuretted hydrogen must be passed through
the solution to precipitate them. The same process is followed in obtaining
sulphate of nickel, nickel ore being substituted for cobalt or speiss. From the
manufacture of azure blue, nickle gives yellow greens of every shade. Nickel
and cobalt united give an olive green, and an imitation of green earth, by the
same process as in obtaining the greens colored by cobalt. Copper gives a
grey and greenish grey; it is used as a sulphate, nitrate, or sulphuret, and
mixed with the blende, following the same process as with the colors colored
by iron. The proportions should not exceed ten to thirteen pounds of sulphate,
nitrate, or an equivalent proportion of sulphuret of copper, to each two hundred
and seventy-four pounds of blende, or, which comes to the same, two hundred
and nineteen pounds of oxide of zinc. Chromium gives a flesh color, as also
a grey verging thereon; it is used as an hydrated oxide dissolved in diluted

page_text: sulphuric acid, or as chrome alum, or the cromates of potassa, or soda, and
added to the blende in proportions varying with the shade of color required.
Thirteen pounds of oxide to two hundred and seventy-four pounds of yellow
blende gives a flesh color, less gives the grey verging thereon, the same
process being followed as for the colors colored by iron, with the exception
that if chromates of potassa have been used the colors must be water-washed
by decantation to dissolve the potassa or soda and afterwards dried. Uranite
or uranium gives a clear grey verging on green; it is employed as a nitrate
(azotate) mixed with yellow blende, and operated upon as the colors colored
by iron; uranium being very expensive may be replaced by copper, but I
wish to include it in this my Specification. To prepare the nitrate of uranium,
dissolve by heat in nitric acid the mineral known as pechblende, and decant
when the action of the acid has ceased, dilute with water, and pass through it
a current of sulphuretted hydrogen to precipitate extraneous metals, and by
Browns of divers shades are obtained
dry evaporation obtain the nitrate.
by admixture to the oxide of manganese of hydrated oxide of chromium
dissolved in diluted sulphuric acid, or of chrome alum, or the cromates of
potassa, or soda added to the blende, in proportions varying with the shade
desired. Violet browns of different shades are obtained by the admixture of
iron with oxide of chromium. Velvety green is obtained by the admixture
of a small quantity of oxide of chromium with the oxide of cobalt; very deep
and velvety olive green by admixture of the oxides of cobalt, chromium,
and manganese.
A black brown is obtained by mixing the oxides of iron,
chromium, manganese, and cobalt. Olive green, bordering upon black, is
obtained by admixture of the oxides of manganese, cabalt, nickel, and other.
[Frecautions to be observed, in order always to obtain the same shade of
color. The same sort of combustible should always be used, be it coal, coke,
or charcoal, in order to obtain invariably the same temperature; it is also
necessary to use the same sort of blende. To obtain pure greens and yellows
yellow blende must be used, or any other quality of blende which after
complete burning or combustion gives a powder white, yellowish, clear yellow,
rose yellow, or very clear ochre red; for deeper colors, on the contrary, blendes
more or less pure may be used as being more economical, inasmuch as they
require less coloring oxide. For example, for deep mahogany brown black
blende should be used; for a lighter, brown blende; and to vary the shades,
yellow and black or brown blendes may be mixed, and small quantities of
coloring oxides may be added. To obtain deeper and more vivid shades,
more especially in greens, without any further addition of coloring oxides,
oxide of calcium (good quicklime) such as may be obtained by the calcination

page_text: of white marble or chalk, is mixed with the colors, in the proportion of ten
parts to one hundred of color, and the tint is varied by increasing or
diminishing the proportion of lime. The operation is conducted as follows:-
The blende or oxide of zinc, together with the coloring oxides, having been
roasted in the same manner as the colors colored by iron, manganese, cobalt
nickel, and other, until no further sulphurous acid is disengaged, the color
is then withdrawn from the furnace, and when sufficiently cooled is
thoroughly mixed with the lime (care having been taken to slacken the lime
with water a few minutes previously), the mixture is then sprinkled with
the one-hundredth part of its weight of chlorhydric or nitic acid diluted by
two or three times its weight of water (care being had to mix the whole
thoroughly); the compound is then placed in the furnace and re-roasted
at a white heat for half an hour, to effect the combination of the oxides; it
is then withdrawn and pulverized. And I would here observe, that fabrics
of cotton or wool, or other textile or woven fabrics, may be printed, using
the colors herein-before mentioned combined with albumen, in the same
way as is practised with such fabrics when lazulite is used.
Description of the overheated reverberatory air furnace which I use in
themanufacture of the colors herein-before described.-The furnaces hitherto
employed in roasting, burning, or baking blende have been very imperfect,
inasmuch as particles of matter remained in the corners and inequalities of
the furnace, and not being acted upon by the heat and air, escaped oxida-
tion, and further requiring a large quantity of fuel, the major part of which
was clear loss, inasmuch as it is only the layer of gas charged with atmo-
spheric air in contact with the blende which is utilised, the rest of the heat
being lost. Again, the cinders and other carbonaceous particles mixing
with the blende deteriorate the remaining product. The gas from the fuel,
the excess of atmospheric air and carbonaceous particles mixing with the
sulphurous acid derived from the oxidation of the sulphur contained in the
blende, deteriorates this product to such a point as to render it almost
inapplicable to the manufacture of sulphuric acid. To obviate these difficulties,
and to exempt my colors from all faults, giving them a bright and pure
shade, I have constructed my improved furnace, the Drawings of which
are hereunto annexed, and which I will now proceed to describe.
Figure 1 represents a horizontal section of the furnace, shewing the sole or
bottom A, which is round, and which should be interiorly about fifteen to six-
teen feet in diameter. On each side of the furnace will be seen an opening or
conduit I, traversing the two soles or bottoms, and ending in the lower reservoir
or receiver U, Figure 4; these are oblong square openings, and are closed

page_text: (during the burning or roasting) by cast-iron plates. The sole or bottom
must be entirely of refractory brick work,about twentyinches square,composed
of two rows together, about three inches in thickness; the remainder of the
circle of the furnace should be made of half-circular refractory bricks, and the
other parts of ordinary fire brick. The bricks composing the bottom and
circle of the furnace should be made of very pure and refractory clay, scoured
by clay burnt at a very high temperature, and by feldspath, in powder fine as
flour. Burnt clay, mixed with pure clay, in powder, about as thick as grains
of millet, should be used, in order to obtain a very compact paste or plaster
resisting the action of heat, and giving forth no impurities to the colors, such
as grains of sand or burnt clay. All interstices in the brick should be care-
fully stopped with refractory earth. Two doors R,,R, one on each side of the
furnace, close the openings through which the work is carried on. 0,0, two
openings, by which escapes the hot air destined to roast the blende spread
upon the sole A. The two muffles O¹, O', occupying part of the grate or
fire place, and terminating at the openings O, O, should be made of very
compact or close refractoryearth, and square,(about fourteen inches interiorly
from side to side, and the partitions about two inches in thickness. The
extreme length of these muffles should be about five feet; they are to be
filled with massive or solid cylinders of burnt clay, two of which are shewn
at Figure 6. The upper part of the grate A, B, should be about thirty-six
inches broad by about five feet long. C, the door by which fuel is supplied;
D, D, compartments through which passes the flame from the fuel, having
circulated round the muffles in order to enter the beneath sole A, heating
the bricks from beneath; (best seen at Figure 5). B, square compartment
of about twenty-two inches from side to side (in thin fire brick), filled with
balls of pumicestone of about three inches in diameter.
At Figure 2 it will be seen that the base of the furnace is square, and
the sole round, and of the same size as sole A, Figure 1; on each side
of the sole are openings I, I, terminating at the lower receiver U. The
object of this sole is to permit the passage of sufficient heat (that is to say
flame from the combustible) to the principal sole A, Figure 1, and serving
at the same time to uphold it by means of fire bricks placed beneath each
brick thereof. a, a, a, represent iron bars resting in the brickwork, and
giving greater solidity to the furnace; F, passage by which the flame of the
combustible leaves the grate of the furnace, following the direction of
the arrows; M, bars forming the grate. On each side of the grate are
three muffles 0, 0, 0, (filled with fire-clay cylinders) of the same dimensions
as those shewn at Figure 1. F¹, conduit or chimney by which the flame

page_text: enters the upper chimney or shaft. The flame, before escaping by the
chimney, passes around the square compartment B, bringing it to a red heat,
together with the pumice stones therein contained.
Figure 3 shews a vertical section, taken through the line X, X, Figure 1;
C shewing the passage or opening for the admission of fuel; A, B, the
grate; M, grating bars; X, ashpit; A, the upper sole on which the blende
is roasted; A, lower sole, through which passes the flame from the fuel;
U, the lower reservoir or receiver into which the colors fall; B, square
compartment in thin refractory brickwork filled with pumicestones, through
which the sulphurous acid, disengaged from the blende passes into the con-
densing chamber G, and from thence to the other chambers; F, chimney
by which the smoke is carried off; K, a pipe of wrought iron, lead, or
better of copper interiorly platinized, through which the sulphurous acid
enters the chambers; L, L, two cast-iron hoppers (containing the charge to
be roasted), which should be furnished with a valve or stopper hermetically
closing the opening, and which when turned permits the charge to fall upon
the sole. The condensing chamber is about five feet broad by about four
feet six inches deep, and should be furnished with a door that it may be
cleaned when necessary.
Figure 4 is a section of the furnace, taken through the line H, H;
Figure 1 shewing the passage of the atmospheric air, the arrows marking
the course it takes in acquiring the necessary temperature before arriving
at the sole, where the blende is resting at a great heat; G, the con-
densing chamber. Figure 5, section taken through the line B, B, Figure 1.
A, B, the fire-place or grate; o¹, o¹, o¹, o', muffles containing the cylinders;
the air enters by the lower openings near the grating, traverses the three
first muffles to arrive in the compartments c, c, and from thence into the
upper muffles o, o¹. M, grating bars; D, D, shews the space traversed by
the flame in passing to the upper sole. Figure 6, represents two of the
cylinders which are placed in the muffles. The entire exterior of the furnace
should be surrounded by strong iron bars to give it greater solidity.
Having now described the nature of my Invention, and the manner in which
I carry it into effect, I desire it to be distinctly understood that while I have
given the measurements, weights, and proportions of parts in the description
of my furnace, and in the combinations for making colors according to my
Invention as nearly as I can, yet I do not confine myself to the absolute
exactitude of such measures, weights, or proportions, as deviations may be
made therefrom, to suit particular circumstances or cases without in anywise
departing from the principle of my Invention, as herein-before set forth and

page_text: fully divulged; and I do not claim the exclusive use of any of the minerals
or other articles or substances herein-named, taken and considered seper-
ately, and not in combination or treated according to my directions, for the
purposes of my Invention, which I declare to be, and I claim, the exclusive
use of colors manufactured from oxide of zinc obtained from blende or
other mineral, by treating such blende or other mineral in the manner and
by the apparatus herein-before set forth and fully described.
In witness whereof, I, the said Charles Sylvester Rostaing, have here-
unto affixed my hand and seal, this 18th day of December, in the
year of our Lord One thousand eight hundred and fifty-six.
Witness,
FREDERIC BELEY,
Professeur,
à Dresde,
CHARLES SYLVESTER ROSTAING. (L.S.)
Moritz Strasse, No. 17.