IMPROVEMENTS IN THE PURIFICATION OF CERAMIC, VITRIFIABLE AND OTHER MATTERS, AS ALSO OF THE CRUCIBLES, FURNACES, OR VESSELS USED FOR CONTAINING THE SAME
Year: 1868

page_text: LETTERS PATENT to Alexander Melville Clark, of 53, Chancery Lane,
in the County of Middlesex, Patent Agent, for the Invention of
"IMPROVEMENTS IN THE PURIFICATION OF CERAMIC, VITRIFIABLE AND OTHER
MATTERS, AS ALSO OF THE CRUCIBLES, FURNACES, OR VESSELS USED FOR
CONTAINING THE SAME."-A communication from abroad by Louis
Clémandot and Emile Rousseau, both of 13, Boulevart St. Martin,
Paris..
Sealed the 8th December 1868, and dated the 17th June 1868.
PROVISIONAL SPECIFICATION left by the said Alexander Melville Clark
at the Office of the Commissioners of Patents, with his Petition, on
the 17th June 1868.
I, ALEXANDER MELVILLE CLARK, of 53, Chancery Lane, in the
County of Middlesex, Patent Agent, do hereby declare the nature of the
said Invention for "IMPROVEMENTS IN THE PURIFICATION OF CERAMIC,
VITRIFIABLE, AND OTHER MATTERS, AS ALSO OF THE CRUCIBLES, FURNACES. OR
VESSELS USED FOR CONTAINING THE SAME," to be as follows:-
This Invention relates to a mode of purifying primary matters

page_text: manufactures, grit produced by cutting glass and crystal, crucible
clays, natural phosphates of lime used as manure, sulphate of baryta,
metallic oxides, and other products used for industrial purposes con-
taining iron (generally in the form of oxide) which it is desired to
eliminate. In the case of glass and crystal, for example, the presence
of iron either in the silica used in the manufacture or even in the
material of which the crucible is composed produces a deep green
discoloration which prejudicially affects the whiteness and purity of the
products.
In certain applications like those of glass and crystal, the glass is
required to be perfectly colorless, and in order to obtain this result I
purify the raw materials by mixing therewith hydrochlorate of ammonia
either Irydrated or not, and bring the whole to a red heat. The pro-
portion of the hydrochlorate depends on the amount of iron found by
analysis to be contained in the matters. This salt transforms the iron into
perchloride of iron, which disengages by volatilization; the matter will.
then be perfectly bleached and exempt from the presence of iron. This
mode of purification is not only applicable to the materials, but also to
the crucibles, furnaces, recipients, or vessels of various kinds in which
the fusion, preparation, or baking of the matters is effected. In order to
purify a crucible, for example, when at a red heat, a certain quantity of
hydrochlorate of ammonia is injected which becomes decomposed and
volatilizes carrying with it all the iron from the sides of the furnace
which become as white as porcelain. In most cases the discoloration
of glass is due to the presence of iron in the crucibles or soles in which
the "frits" are prepared. It is unnecessary to add that the soles of the
furnaces may either be purified in the manner above described with
reference to the crucibles or may be made of materials purified in a
similar manner. The purification of the matters above specified by
mixing with hydrochlorate of ammonia either in solution or in a solid
form may also be effected by subjecting the matter to be purified to the
action of the vapour of hydrochlorate of ammonia, and when operating
on a large scale it may be of advantage to collect by condensation the
vapors of the hydrochlorate unconverted into perchloride. Further in
the manufacture of glass and crystal an obstacle is presented to the
employment of soda through the intensity of the color produced by the
iron and soda which is much greater than when employing iron and
potash; hence by the adoption of the mode of purification of this

page_text: Invention soda may be substituted for the potash, producing a white
colorless glass with a base of soda exactly similar to that produced with
a base of potash but at a greatly reduced cost.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Alexander Melville Clark, in the Great Seal Patent
Office on the 16th December 1868.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, ALEXANDER
MELVILLE CLARK, of 53, Chancery Lane, in the County of Middlesex,
Patent Agent, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Seventeenth day of June, in the year of
our Lord One thousand eight hundred and sixty-eight, in the thirty-
first year of Her reign, did, for Herself, Her heirs and successors, give
and grant unto me, the said Alxander Melville Clark, Her special
licence that 1, the said Alexander Melville Clark, my executors, adminis-
trators, and assigns, or such others as I, the said Alexander Melville
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
" Ix-
PROVEMENTS IN THE PURIFICATION OF CERAMIC, VITRIFIABLE, AND OTHER MATTERS,
AS ALSO OF THE CRUCIBLES, FURNACES, OR VESSELS USED FOR CONTAINING THE
SAME," a communication to me from abroad by Louis Clémandot and
Emile Rousseau, both of 13, Boulevart St. Martin, l'aris, upon the
condition (amongst others) that I, the said Alexander Melville Clark,
my executors or administrators, by an instrument in writing under
my, or their, or one of their hands and seals, 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
month next and immediately after the date of the said Letters
Patent:
NOW KNOW VE that T
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page_text: is to be performed, to be particularly described and ascertained in and
by the following statement (that is to say) :-
This Invention relates to a mode of purifying primary matters, such as
kaolin, ceramic clay, feldspath sand used in glass and crystal manu-
factories, grit produced by cutting glass and crystal, crucible clays,
natural phosphates of lime used as manure, sulphate of baryta, metallic
oxides and other products, used for industrial purposes containing iron
(generally in the form of oxide) which it is desired to eliminate. In the
case of glass and crystal, for example, the presence of iron either in
the silica used in the manufacture or even in the material of which
the crucible is composed produces a deep green discoloration which
prejudicially affects the whiteness and purity of the products.
In certain applications, like those of glass and crystal, the glass is
required to be perfectly colorless, and in order to obtain this result I
purify the raw materials by mixing therewith hydrochlorate of ammonia,
either hydrated or not, and bringing the whole to a red heat. The pro-
portion of the hydrochlorate depends on the amount of iron found by
analysis to be contained in the matters. This salt transforms the iron
into perchloride of iron, which disengages by volatilization; the material
will then be perfectly bleached and exempt from the presence of iron.
This mode of purification is not only applicable to the materials, but also
to the crucibles, furnaces, recipients, or vessels of various kinds in
which the fusion, preparation, or baking of the matters is effected. In
order to purify a crucible, for example, when it is at a red heat, a certain
quantity of hydrochlorate of ammonia is injected which becomes de-
composed and volatilizes, carrying with it all the iron from the sides of
the furnace which become as white as porcelain. In most cases the
discoloration of glass is due to the presence of iron in the crucibles or
soles in which the frits are prepared. It is unnecessary to add that the
soles of the furnaces may either be purified in the manner above
described with reference to the crucibles, or may be made of materials
purified in a similar manner. The purification of the matters before
specified by mixing with hydrochlorate of ammonia either in solution or
in a solid form may also be effected by subjecting the matters to be
purified to the action of the vapour of hydrochlorate of ammonia, and
when operating on a large scale it may be of advantage to collect by
condensation the vapors of the hydrochlorate unconverted into perchloride.
Further, in the manufacture of glass and crystal an obstacle is pre-

page_text: sented to the employment of soda through the intensity of the color
produced by the iron and soda which is much greater than that
obtained when employing iron and potash; hence by the adoption of
the mode of purification of this Invention soda may be substituted for
the potash without damaging the whiteness and producing a white
colorless glass with a base of soda exactly similar to that produced
with a base of potash but at a greatly reduced cost.
The Invention thus consists in a mode of bleaching glass, crystal, por-
celain, enamels, and other ceramic materials, and generally of all vitrifiable
or ceramic products. I have before mentioned that I obtain this result
by the aid of hydrochlorate of ammonia, which under the influence of
the heat neither decrepitates nor passes into a state of aqueous fusion, but
becomes converted into vapours, which after first causing the iron to pass
into a state of perchloride combine therewith in order to vaporize and
eliminate the iron. I have stated that the hydrochlorate of ammonia
is placed in the required quantity either in the paste or in the glaze
or material forming the crucibles or other vessels used for the fusion,
hardening, or other treatment, for the purpose of purifying the surfaces
of said vessels of the salts of iron contained, which tend to tinge the
products. An analogous result may also be obtained by the use of
any ammoniacal substance (such as ammoniacal salts, urine, or animal
matter); in this case the transformation into volatile perchloride does
not take place, such matter serving as a reducer to prevent more or
less (by means of the ammoniacal atmosphere formed) the super-
oxidation of the iron, which as is well known has a greater coloring
action in the form of peroxide than in that of protoxide. The presence
of the ammonia may also hasten certain stages of the manufacture.
Having described the nature of this Invention and the manner of
performing the same, I declare that what I claim as the Invention to
be protected by the herein-before in part recited Letters Patent is,
purifying matters used in the manufacture of glass, crystal, porcelain,
or china, and also enamels, kaolin, phosphates of lime, feldspath, and
generally all primary matters containing iron in the form of oxide or
other salts (coloring the same or liable to tinge the matters after their
transformation, which iron it is desired to eliminate) by the aid of
hydrochlorate of ammonia or a suitable ammoniacal salt, or it may be
ammonia, with which the iron combines in a volatile form, all in the
manner herein-before described.

page_text: It will be understood that this mode of purification is applicable
either separately or simultaneously both to the matters themselves, and
to their containing vessels, crucibles, or furnaces.
In witness whereof, I, the said Alexander Melville Clark, have
hereunto set my hand and seal, this Sixteenth day of December,
in the year of our Lord One thousand eight hundred and sixty-
eight.
Witness,
JAMES DAISH,
53, Chancery Lane,
London.
A. M. CLARK. (L.S.)