A New or Improved Method of Manufacture of certain Compounds of Chromium used in Dyeing and Calico Printing.
Year: 1891

page_text: Date of Application, 24th Feb., 1891
Complete Specification Left, 23rd Nov., 1891-Accepted, 24th Dec., 1891
PROVISIONAL SPECIFICATION.
A New or Improved Method of Manufacture of certain Compounds
of Chromium used in Dyeing and Calico Printing.
We, WILLIAM WATSON of 60 George Street; Manchester, in the County of
Lancaster, Calico Printer, and ERNEST BENTZ of Owens College, Manchester; in
the County of Lancaster, Lecturer on Applied Chemistry, do hereby declare the
nature of this invention to be as follows:-
This invention relates to the method of manufacture of certain compounds of
chromium, which are employed for mordanting purposes in calico printing and to
some extent in dyeing.
By means of this invention we prepare the following chromium compounds:
Chromium acetate, chromium basic acetate, chromium nitrate, chromium basic
nitrate, and mixtures of chromium acetate or chromium basic acetates with one or
more of the following: chromium sulphate, chromium basic sulphate, chromium
chloride, chromium basic chloride, chromium nitrate, chromium basic nitrate,
chromium sulphite. We manufacture the aforesaid compounds or mixtures of
compounds by the reduction of chromic acid, liberated from preferably sodium
bichromate or a mixture of sodium bichromate and sodium chromate, with sulphurous
acid, in the presence of, or with the subsequent addition of, the sodium salt or salts
of the acid or acids corresponding to the compound or mixture of compounds of
chromium it is desired to produce. The mixtures are made of such a degree of
concentration, that is, with the addition of such an amount of water, that, on cooling,
after the reaction, as much as possible of the sodium sulphate, which is formed in
the reaction, may crystallise out in the hydrated state. We give below an example
of the method by which we manufacture, according to the present invention,
chromium acetate: 100 lb. of sodium bichromate are mixed with, or dissolved in,
550 lb. of 25 per cent. acetic acid, or a mixture of a proportionally less quantity of
stronger acid with water to make up this amount of dilute acid, then 357 lb. of
sodium bisulphite solution, containing 33 per cent. of sodium bisulphite, are added
gradually. The mixture becomes hot. When the amount of sodium bisulphite
mentioned has been added, the mixture is allowed to cool and stand for a few days
to allow the sodium sulphate to crystallise out, a further quantity of this salt being
caused to crystallise out after another day or two's subsequent rest by the addition
of 20 lb. of sodium carbonate to the solution of chromium salt or salts. The sodium
carbonate may be added to the sodium bichromate before or after the addition of
acetic acid, or to the sodium bisulphite or may be added whilst the reduced
chromium salt or salts are still hot from the reaction, instead of being added some
time after the termination of the reaction as herein described, and it may be
replaced by sodium hydrate, sodium bicarbonate, calcium oxide, calcium hydrate,
calcium carbonate or the similar compounds of magnesium, ammonia, or potassium,
in equivalent amount. The reduction may be, further, effected by sulphurous acid
which is passed in the gaseous state, that is, as sulphur dioxide, into the solution
of sodium bichromate in acetic acid, until the chromic acid is completely reduced
to a salt or salts of chromic hydrate, when sodium carbonate, sodium hydrate, or
sodium bicarbonate is added in sufficient amount to neutralise the sulphuric acid
which is formed. The necessary amount of sodium carbonate, sodium hydrate, or
sodium bicarbonate may be added to the mixture of sodium bichromate and acetic
acid prior to the treatment with sulphur dioxide, or may be added gradually whilst
the treatment is proceeding.
Instead of sodium bisulphite, a mixture of sodium sulphite or sodium thiosulphate

page_text: with a sufficient amount of sulphuric acid to form a mixture of sodium sulphate and
sodium bisulphite, may be used.
We manufacture, according to the present invention, basic chromium acetate, for
example, by reducing the amount of acetic acid required to produce the normal
salt as in the example given, to form five-sixths to one-half this amount, thus with
the quantities given in the example of the application of our method herein
described, the amount of acetic acid may, in the preparation of chromium basic
acetate be reduced to say 300 lb., 250 lb. of water being added to the sodium
bichromate, along with such amount of 25 per cent. acetic acid.
Solutions of sodium bisulphite of somewhat different strength than that we
mention in the example given herein, may be used, correspondingly larger or
smaller quantities being then required and the weight of the complete mixture of
sodium bichromate, acetic acid, sodium carbonate, and sodium bisulphite, being
kept constant by the use of acetic acid of higher percentage than 25, or by the
addition of water, according as bisulphite of soda of less or higher percentage
than 33 is used.
The amount of sodium bisulphite of 33 per cent. strength which we state herein
is required for the reduction of 100 lb. of sodium bichromate, is only approximate,
the addition of sodium bisulphite being, if necessary continued, until, in fact, all the
chromic acid is reduced to form a salt or mixture of salts of chromic oxide.
Dated this 23rd day of February 1891.
W. WATSON.
ERNEST BENTZ.
COMPLETE SPECIFICATION.
A New or Improved Method of Manufacture of certain Compounds
of Chromium used in Dyeing and Calico Printing.
We, WILLIAM WATSON, of 60, George Street, Manchester, in the County of
Lancaster, Calico Printer, and ERNEST BENTZ, of Owens College, Manchester, in
the County of Lancaster, Lecturer on Applied Chemistry, do hereby declare the
nature of this invention and in what manner. the same is to be performed, to be
particularly described and ascertained in and by the following statement :-
or
This invention relates to the manufacture of certain compounds of chromium
which are employed for mordanting purposes in calico-printing and to some extent
in dyeing. By means of this invention we prepare the following chromiun
compounds-Chromium acetate, chromium basic acetate, chromium sulphite, and
mixtures of these salts with one another and with chromium sulphate or with
chromium basic sulphate. We manufacture according to this invention the afore-
said compounds or mixtures of compounds by the reduction with sulphurous acid
of the chromic acid contained in sodium bichromate or in sodium chromate or in a
mixture of sodium bichromate and sodium chromate, in the presence or with the
subsequent addition of the acid or acids or of the sodium salt or salts of the acid
or acids whose chromium salt or salts it is desired to produce, a sufficient amount
of sodium carbonate, sodium bicarbonate, or sodium hydrate being, if necessary,
also added to combine with the sulphuric acid which is formed in such reaction.
The solution of sodium.bichromate or of sodium chromate or of the mixture
of sodium bichromate and sodium chromate, is made of such a degree of
concentration, that is, with the addition of such an amount of water, or of dilute
acid, that on cooling after the said reaction, as much as possible of the sodium
sulphate formed in the reaction, may crystallise out in the hydrated state. We give
below an example of the method by which we manufacture according to the present
invention, chromium acetate:-112 lb. of commercial sodium bichromate (containing
90 per cent. of pure sodium bichromate) are dissolved in 550 lb. of 25 per cent. acetic
acid, or in a mixture of a proportionately less quantity of stronger acid with water

page_text: to make that amount of dilute acid, then 400 lh. of a 30 per cent. solution of sodium
bisulphite are added gradually so as to avoid any considerable rise of temperature.
When the amount of sodium bisulphite mentioned has been added, the mixture is
allowed to cool and stand for several hours or days to allow the greater portion of
the sodium sulphate which is formed to crystallise out, a further quantity of sodium
sulphate being caused to crystallise out after further standing by the addition to
the mixture of a concentrated aqueous solution of 20 lb. of sodium carbonate, or
an equivalent amount of sodium hydrate, sodium bicarbonate, or sodium acetate.
We manufacture according to the present invention chromium basic acetate by
reducing in the above recipe for the manufacture of chromium acetate, the pro-
portion of 25 per cent. acetic acid given therein, to, for example, one-half of that
amount, that is, in the said recipe to, for example, 275 lb., 275 lb. of water being
also used along with such amount of 25 per cent. acetic acid. Solutions of sodium
bisulphite of somewhat different strength to that mentioned in the above recipes,
may be used instead of the 30 per en, solution of such salt mentioned therein,
proportionately larger or smaller amounts of such solutions than of the 30 per cent.
solution, being then required and the total weight of sodium bichromate, acetic
acid, sodium bisulphite, and sodium carbonate being kept constant by the use of
acetic acid of greater strength than 25 per cent. or by the addition of water,
according as sodium bisulphite solution of less or higher percentage than 30
is used.
We manufacture, according to the present invention, chromium sulphite, by
dissolving 112 lb. of sodium bichromate (containing 90 per cent. of pure sodium
bichromate) in 400 lb. of water, adding 39 lb. of sulphuric acid (containing
95 per cent. of H₂SO) and then gradually adding 800 lb. of a 30 per cent. solution
of sodium bisulphite (or a proportionately less amount of stronger solution of
sodium bisulphite or proportionately larger amount of more dilute solution of
sodium bisulphite), then cooling and allowing the mixture to stand for several hours
or days to enable the greater portion of the sodium sulphate which is formed, to
crystallise out.
The reduction of the chromic acid may also be effected by sulphurous acid which
is passed in the gaseous state, that is, as sulphur dioxide, into a solution of sodium
bichromate in water or dilute acetic acid, according as it is desired to manufacture
chromium sulphite or chromium acetate, until the chromic acid contained in the
sodium bichromate is completely reduced, and, when chromium sulphite is being
manufactured by such method, continuing the passage of the said gas until a
sufficient quantity of sulphurous acid is present in the solution to form chromium
sulphite, and then adding a sufficient amount of sodium hydrate or of sodium
carbonate or of sodium bicarbonate to neutralise or combine with the sulphuric
acid which is formed in the reaction, so producing sodium sulphate which crystallises
out from the solution of chromium sulphite or of chromium acetate on cooling and
standing. Sulphurous acid, passed into the solution of sodium bichromate as sulphur
dioxide, may also be similarly employed, according to this invention, along with
one or more of the following compounds, namely, acetic acid, sulphuric acid, sodium
carbonate, (or sodium hydrate or sodium bicarbonate), sodium sulphite, sodium
thiosulphate, or sodium acctate, to produce mixed solutions of chromium sulphite
and chromium sulphate (a mixed solution of two molecular proportions of chromium
sulphate and one molecular proportion of chromium sulphite is obtained according
to this invention by passing sulphur dioxide into a suitably diluted aqueous solution
of sodium bichromate until the chromic acid is reduced, and allowing the solution to
stand, after cooling, to crystallise out the greater portion of the sodium sulphate
which is formed), of chromium sulphite and chromium basic sulphate, of chromium
acetate and chromium sulphate, of chromium acetate and chromium basic sulphate,
of chromium sulphate, chromium acetate and chromium sulphite, and of chromium
basic sulphate, chromium acetate and chromium sulphite.
We manufacture, according to the present invention, a mixture of chromium
acetate and of chromium sulphate by replacing a portion of the amount of acetic

page_text: acid stated herein in the recipe for the manufacture, according to our method, of
chromium acetate, by an equivalent amount of sulphuric acid, a sufficient amount
of water being added to make the total amount of the materials employed the same
as that in the said recipe, the weights of sodium bichromate, sodium bisulphite and
sodium carbonate remaining the same as are given in the said recipe, or, instead of
this, we employ only half the quantity of sulphuric acid which would be required
in the place of that portion of the acetic acid which is replaced by such acid in the
manufacture of a mixed solution of chromium acetate and chromium sulphate, and
then omit the sodium carbonate (or sodium hydrate or sodium bicarbonate), the
materials employed in this latter case consisting of sodium bichromate, sodium
bisulphite, sulphuric acid, acetic acid, and water. We manufacture, according to
this invention, a mixed solution of chromium acetate and of chromium basic
sulphate, by reducing the amount of acetic acid or of sulphuric acid employed in
the manufacture by our method of a mixed solution of chromium sulphate and of
chromium acetate, or by omitting any addition of sulphuric acid and of sodium
carbonate (or sodium hydrate or sodium bicarbonate) to the mixture of materials
employed for the manufacture of such mixed solution of chromium sulphate and of
chromium acetate, the materials employed in such latter case for the manufacture
by our method of a mixed solution of chromium acetate and chromium basic
sulphate consisting of sodium bichromate, sodium bisulphite, acetic acid, and
water.
We manufacture, according to the present invention, a mixed solution of
chromium sulphite and of chromium sulphate, by taking, for example, 112 lb. of
sodium bichromate (90 per cent.) dissolving the same in 400 lb. of water, adding
60 lb. of sulphuric acid (95 per cent.) and then gradually 667 lb. of sodium
bisulphite solution (30 per cent.) and afterwards cooling and allowing to stand to
separate by crystallisation the greater portion of the sodium sulphate formed, from
the mixed solution of chromium sulphite and chromium sulphate.
Similarly, we manufacture according to this invention, a mixed solution of
chromium basic sulphate and of chromium sulphite by reducing the amount of
sulphuric acid employed in the manufacture of a mixed solution of chromium
sulphite and of chromium sulphate as in the example given, to, for example,
30 lb. of 95 per cent. sulphuric acid, the quantities of the other materials, namely,
of the sodium bisulphite, sodium bichromate, and water, mentioned in the said
recipe, remaining the same as given therein.
We manufacture according to the present invention a mixed solution of chromium
sulphite and of chromium acetate by dissolving 112 lb. of sodium bichromate
(containing 90 per cent. of pure sodium bichromate) in 100 lb. of water and 367 lb.
of 25 per cent. acetic acid, and then gradually adding 534 lb. of 30 per cent. sodium
bisulphite solution, and allowing to cool and stand to separate by crystallisation the
greater part of the sodium sulphate formed. Similarly, we manufacture according
to the present invention a mixed solution of chromium sulphite, chromium sulphate
and chromium acetate by replacing part of the acetic acid in the recipe given for
the manufacture according to our method of a mixed solution of chromium sulphite
and chromium acetate, by its equivalent of sulphuric acid along with so much
water in addition as will make the total weight of the materials used the same as is
in the said recipe, the amounts of the other materials, namely, of the sodium
bichromate and sodium bisulphite, remaining the same as are given in the said
recipe. Similarly, we manufacture, according to this invention, a mixed solution of
chromium basic sulphate, chromium sulphite, and chromium acetate, by reducing
the proportion of acetic acid employed in the process of manufacturing, according
to our method, a mixed solution of chromium sulphate, chromium sulphite and
chromium acetate, as described herein.
The solutions of chromium acetate, chromium basic acetate, and chromium
sulphite, and the mixed solutions of chromium sulphate and chromium acetate, of
chromium basic sulphate and chromium acetate, of chromium sulphate and chromium
sulphite, of chromium basic sulphate and chromium sulphite, of chromium sulphite

page_text: and chromium acetate, of chromium sulphate chromium sulphite and chromium
acetate, and of chromium basic sulphate chromium sulphite and chromium acetate,
obtained as described herein, may be artificially cooled (by refrigeration) to remove
more perfectly (by crystallisation) the sodium sulphate which such solutions still
contain after being allowed to stand to cause the removal by crystallisation from
them of the greater part of the sodium sulphate which they originally contained,
but, in general, such solutions, after standing, are ready for use in dyeing or calico-
printing without being subjected to such artificial cooling.
Instead of the sodium bichromate containing 90 per cent. of pure sodium bichromate
mentioned herein, commercial sodium bichromate of somewhat different content
in pure sodium bichromate may be used in our method of manufacturing the various
chromium salts or mixtures of chromium salts, herein described, the recipes given
herein, being in such case suitably modified as regards the quantity required of such
commercial sodium bichromate.
Having now particularly described and ascertained the nature of our said inven-
tion and in what manner the same is to be performed, we declare that what
we claim is :-
1. The method of manufacturing chromium acetate solution substantially as
herein described.
2. The method of manufacturing chromium basic acetate solution substantially
as herein described.
3. The method of manufacturing chromium sulphite solution substantially as
herein described.
4. The method of manufacturing a mixed solution of chromium sulphate and of
chromium acetate, substantially as herein described.
5. The method of manufacturing a mixed solution of chromium sulphate and of
chromium sulphite, substantially as herein described.
6. The method of manufacturing a mixed solution of chromium basic sulphate
and of chromium acetate, substantially as herein described.
7. The method of manufacturing a mixed solution of chromium basic sulphate
and of chromium sulphite substantially as herein described.
8. The method of manufacturing a mixed solution of chromium sulphate,
chromium sulphite and chromium acetate, substantially as herein described.
9. The method of manufacturing a mixed solution of chromium basic sulphate,
chromium sulphite and chromium acetate, substantially as herein described.
Dated this Twentieth day of November 1891.
WILLIAM WATSUN.
ERNEST BENTZ.