IMPROVEMENTS IN THE PREPARATION OF HYDRATED OXIDE OF CHROMIUM
Year: 1858

page_text: LETTERS PATENT to William Armand Gilbec. of No. 4, South Street,
Finsbury. London, Patent Agent, for the Invention of "IMPROVEMENTS
IN THE PREPARATION OF HYDRATED OXIDE OF CHROMIUM. A communication.
Scaled the 1st November 1858, and dated the 28th July 1858.
PROVISIONAL SPECIFICATION left by the said William Armand Gilbee
at the Office of the Commissioners of Patents, with his Petition, on the
28th July 1858.
I, WILLIAM ARMAND GILBEE, of No. 4, South Street, Finsbury, London.
Patent Agent, do hereby declare the nature of the Invention of "IMPROVE.
MENTS IN THE PREPARATION OF HYDRATED OXIDE OF CHROMIUM," to be as
follows, that is to say:-
The Invention communicated to me consists in certain processes for pre-
paring hydrated oxide of chromium applicable to painting, colouring, or
printing textile and other materials. The new oxide differs by its fine green
colour from the ordinary hydrated oxide, which is of a bluish gray colour. It
may be mixed with any of the other colours or mordants. It is obtained by
the following processes:-
First, I raise to a dark red heat a mixture consisting of one part of
bichromate of potass and three parts boracic acid, and throw it into water,
and wash it with hot water so as completely to remove the borate of potass,
and by evaporating the wash waters and adding muriatic acid, the boracic
acid is reformed and can be utilized in great part.
Secondly, replace the bichromate of potass used in the first preparation
by chromate of soda prepared by double decomposition with nitrate of soda
and neutral chromate of potass, or with nitrate of soda and a mixture of

page_text: neutral chromates of soda and potass obtained by saturating the bichromate of
potass with carbonate of soda. The nitrate of potass may be recovered. In
the last process the wash waters contain borax, which may be used or con-
verted into boracic acid. The colour thus prepared is of a clearer tint than
that of the oxide obtained by the first process.
In this mode of preparing hydrated oxide of chromium, the boracic acid
may be replaced by other acids or salts having an acid reaction, such as silicic
acid, alumina, and acid phosphate of lime. Other chromates or chromic salts
may also be employed, such as chromate of lime and alum. Other hydrated
sesqui-oxides, such as the sesqui-oxide of iron, may be prepared by the action
of boracic acid upon suitable compositions.
SPECIFICATION
in pursuance of the conditions of the Letters Patent, filed.
by the said William Armand Gilbee in the Great Seal Patent Office on
the 21st January 1859.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, WILLIAM
ARMAND GILBEE. of No. 4, South Street, Finsbury, London, Patent Agent,
send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Twenty-eighth day of July, in the year of our Lord
One thousand eight hundred and fifty-eight, in the twenty-second year of Her
reign, did, for Herself, Her heirs and successors, give and grant unto me, the
said William Armand Gilbee, Her Special licence, that I, the said William
Armand Gilbee, my executors, administrators, and assigns, or such others as
I, the said William Armand Gilbee, 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 of "IMPROVE
MENTS IN THE PREPARATION OF HYDRATED OXIDE OF CHROMIUM," communicated to
me by a foreigner residing abroad, upon the condition (amongst others) that
I, the said William Armand Gilbee, 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 months next and
immediately after the date of the said Letters Patent.

page_text: NOW KNOW YE, that I, the said William Armand Gilbee do hereby
declare the nature of the said Invention, and in what manner the same is to
be performed. to be particularly described and ascertained in and by the
following statement, that is to say:-
The Invention communicated to me consists in processes for preparing
hydrated oxide of chromium on a large scale of a finer color than the chrome
greens hitherto obtained, and applicable by known means in painting and
printing every kind of tissue, and for colouring paper.
The hydrated oxide prepared by the processes herein-afier described is
decomposable only at a temperature approximating to red heat, and is a fast
color. It differs by the beauty of its green tint from the ordinary hydrated
oxide, which is of a bluish gray, and may be at once distinguished from the
anhydrous oxide of chromium (chrome green). first, by its color, and secondly.
by the action of heat upon it. The improved oxide when heated to about
eight hundred degrees Fahrenheit gives off water. and blackens in decom-
posing. The product obtained is not liable to be affected by the action of the
air or light, or by chemical agents. with the exception of concentrated boiling
acids. It may, therefore, be mixed with any color or mordant without
affecting the resulting products. This improved color can be manufactured by
two principal processes.
First process. I heat on the sole plate or bed of a reverberatory furnace
kept at a dull red heat, a mixture consisting of one part of bichromate of
potass, and three parts of refined boracic acid, the whole being moistened with
a quantity of water sufficient to form a thick paste. (Note.-A dull red heat
must not be exceeded, otherwise the substance would completely fuse instead
of remaining in the form of a porous mass, and the oxide formed would pass
into the anhydrous state. and, as is well known, the anhydrous oxide of
chromium is of a dull green colour.) I throw this mass while it is red hot
into cold water, and wash it with boiling water to completely remove from it
the borate of potass which has been formed. The improved hydrated oxide
remains behind, and may be at once collected and dried for use. By evapo-
rating the waters used in washing and adding muriatic acid, the boracic
acid will be recovered, and can be re-employed in great part. The chloride
of potassium resulting from the preceding operation forms an article of
commerce.
Second process. I replace in the first preparation the bichromate of
potass by an equal quantity of chromate of soda obtained by dissolving in
boiling water sixty-one parts of neutral chromate of potass, and fifty-three
parts of nitrate of soda, using the boracic acid as before described. The

page_text: - neutral chromate of potass in this latter case may be replaced by a mixture of
ninety-two parts of bichromate of potass, and eighty-nine parts of crystallized
carbonate of soda, the same quantity of nitrate of soda being employed. In
both cases the solution deposits in cooling a large quantity of nitre, which may
.be sold to the trade and defrays part of the expenses. The mother water
contains the chromate of soda, which may be purified by crystallization, or as
this salt crystallizes with difficulty, the liquor may be evaporated to dryness,
and provided all the nitre, is deposited, the chromate of soda will be sufficiently
pure to be employed as herein-before described. In the second process for the
preparation of chromate of soda, the proportions above stated produce twice
as much chromate of soda as those of the first process.
When the green is
manufactured with chromate of soda the wash waters contain borax, which
may be sold direct to the trade. or which may be converted into boracic acid
by means of muriatic acid. The color prepared with chromate of soda is a
green of a lighter tint than that produced with the bichromate of potass.
Still lighter tints of green may be obtained. if required. by adding to the
mixture of boracic acid and bichromate of potass some alumina, magnesia,
or artificial sulphate of baryta, before introducing it into the reverberatory
furnace. In manufacturing the green, I can replace the chromates of potass
or soda by the chromate of lime, prepared directly by calcining the mineral
chromium (chrome iron) with chalk by the action of an oxidizing flame.
And having now described the nature of the Invention communicated to
me, and the manner of carrying the same into effect, I wish it to be under-
stood that I do not confine myself to the precise proportions herein laid down,
provided the object of the Invention be attained. What I claim is the
processes for the manufacture on a large scale of hydrated oxide of chromium,
decomposable only at a temperature approximating to red heat, and of a fine
and fast color, and applicable to all the purposes for which mineral colors are
usually employed, as herein-before described. .
Jn witness whereof, I, the said William Armand Gilbec, have hereunto
set my hand and seal, this Twentieth day of January, One thousand
eight hundred and fifty-nine.
W. A. GILBEE. (L.S.)