IMPROVEMENTS IN AND CONNECTED WITH THE MANUFACTURE OF CHROMATES
Year: 1875

page_text: LETTERS PATENT to Joseph Townsend, of Glasgow, in the County
of Lanark, North Britain, Manufacturing Chemist, for the Inven-
tion of "IMPROVEMENTS IN AND CONNECTED WITH THE MANUFACTURE OF
CHROMATES."
Sealed the 16th May 1876, and dated the 2nd December 1875.
PROVISIONAL SPECIFICATION left by the said Joseph Townsend
at the Office of the Commissioners of Patents, with his Petition,
on the 2nd December 1875.
I, JOSEPH TOWNSEND, of Glasgow, in the County of Lanark,
North Britain, Manufacturing Chemist, do hereby declare the nature
of the said Invention for "IMPROVEMENTS IN AND CONNECTED WITH THE
MANUFACTURE OF CHROMATES," to be as follows, that is to say :-
This Invention has for its object to improve and render less costly the
processes employed in making chromates, and consists essentially in using
a mixture of lime and magnesia or of their carbonates in processes in
which hitherto lime has been used alone or along with other substances.

page_text: The presence of the magnesia prevents the fluxing of the mixture when
heated, and facilitates the subsequent lixiviation, whilst it admits of
comparatively small quantities of lime being used and of the cost for
materials and fuel being reduced.
In carrying out the Invention according to one process 100 parts à
by weight of any suitable compound containing about 50 parts of
sesquioxide of chromium are mixed with 113 parts sulphate of potash
or 94 parts sulphate of soda, and with 150 parts of a substance such as
dolomite, containing about 54 parts carbonate of magnesia and 87 parts
carbonate of lime.
By a second process 100 parts of the chromium compound are mixed
with 56 parts sulphate of potash or 47 parts sulphate of soda, and with
100 parts dolomite or compound of lime and magnesia.
1
By a third process 100 parts of the chromium compound are mixed
with 90 parts carbonate of potash or 65 parts carbonate of soda, and 1
with 150 parts dolomite or compound of-lime and magnesia.
By a fourth process 100 parts of the chromium compound are mixed
with 45 parts carbonate of potash or 32 parts carbonate of soda, and
with 100 parts dolomite or compound of lime and magnesia.
By a fifth process 100 parts of the chromium compound are mixed
with 66 parts nitrate or nitrite of potash, or 55, parts nitrate or nitrite
of soda, and with 100 parts dolomite or compound of lime and
magnesia.
By a sixth process 100 parts of the chromium compound are mixed
with 132 parts nitrate or nitrite of potash, or 111 parts nitrate or nitrite a
of soda, and with 150 parts of dolomite or compound of lime and
magnesia.
By a seventh process 100 parts of the chromium compound are mixed
with 66 parts nitrate or nitrite of potash, or 55½ parts of nitrate or
nitrite of soda, and 57 parts sulphate of potash or 46%, parts sulphate:
of soda, and with 150 parts dolomite or compound of lime and
magnesia.
By an eighth process 100 parts of the chromium compound are
mixed with 105½, parts nitrate or nitrite of lime, and with 113 parts
sulphate of potash or 94 parts sulphate of soda, and with 150 parts
dolomite or compound of lime and magnesia.

page_text: By a ninth process 100 parts of the chromium compound are mixed
with 53 parts nitrate or nitrite of lime, and with 56½ parts sulphate of
potash or 47 parts sulphate of soda, and with 100 parts dolomite or
compound of lime and magnesia.
In all the processes the proportions may be modified to some extent
without inconvenience. For the dolomite a similar compound may be
substituted by mixing magnesite (carbonate of magnesia) and carbonate
of lime. The dolomite or compound of lime and magnesia may be
freed or partially freed from carbonic acid before being mixed with the
other ingredients. When the chromium compound contains a different
proportion from that mentioned of sesquioxide of chromium the pro-
portions of the other ingredients should be modified accordingly.
The several ingredients are by preference ground together or mixed in
a ground state, or any soluble ingredient may be added in solution, and
the mixture is subjected in the usual way to the heat necessary for
effecting the oxidation. The chromates are afterwards separated by
lixiviation, and may be treated in any known way.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Joseph Townsend in the Great Seal Patent
Office on the 1st June 1876.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JOSEPH
TOWNSEND, of Glasgow, in the County of Lanark, North Britain,
Manufacturing Chemist, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Second day of December, in the
year of our Lord One thousand eight hundred and seventy-five, in
the thirty-ninth year of Her reign, did, for Herself, Her heirs and
successors, give and grant unto me, the said Joseph Townsend, Her
special licence, that I, the said Joseph Townsend, my executors,
administrators, and assigns, or such others as I, the said Joseph
Townsend, 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

page_text: make, use, exercise, and vend, within the United Kingdom of Great
Britain and Ireland, the Channel Islands, and Isle of Man, an In-
vention for "IMPROVEMENTS IN AND CONNECTED WITH THE MANUFACTURE OF
CHROMATES," upon the condition (amongst others) that I, the said
Joseph Townsend, 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.
NOW KNOW YE, that I, the said Joseph Townsend, do hereby
declare the nature of my said Invention, and in what manner the
same is to be performed, to be particularly described and ascertained
in and by the following statement in writing, that is to say:
My said Invention has for its object to improve and render less costly
the processes employed in making chromates, and consists essentially in
using a mixture of lime and magnesia, or of carbonates or other salts of
them in processes in which hitherto lime has been used alone or along
with other substances, or in other more or less analogous processes
which may be advantageously employed for the production of chromates.
The presence of the magnesia prevents the fluxing of the mixture when
heated and facilitates the subsequent lixiviation, whilst it admits of
comparatively small quantities of lime being used and of the cost for
materials and fuel being reduced.
My Invention may be practically carried out in a variety of ways,
but in order that the manner of performing it may be properly
understood I now proceed to state the substances or ingredients, and
the proportions thereof, which I prefer to use in a number of processes
for obtaining chromates to which my improvements are applicable.
In a first process 100 parts by weight of chrome ore or any suitable
compound containing about 50 parts of sesquioxide of chromium are
mixed with 113 parts sulphate of potash, or 94 parts sulphate of soda,
and with 150 parts of a substance such as dolomite, containing about
54 parts carbonate of magnesia and 87 parts carbonate of lime. In
this process chromate of potash or of soda and sulphate of lime are
formed..

page_text: In a second process 100 parts of the chromium compound are mixed
with 56 parts sulphate of potash or 47 parts sulphate of soda, and with
100 parts dolomite to form chromate of potash or soda, chromate of
lime, and sulphate of lime.
In a third process 100 parts of the chromium compound are mixed
with 90 parts carbonate of potash or 60 parts potash, or 65 parts
carbonate of soda or 40 parts soda, and with 150 parts dolomite, to
form chromate of potash or soda, the dolomite serving mainly to
prevent fusion.
In a fourth process 100 parts of the chromium compound are mixed
with 45 parts carbonate of potash or 30 parts potash, or 32 parts
carbonate of soda or 20 parts soda, and with 100 parts dolomite to form
chromate of potash or soda and chromate of lime.
In a fifth process 100 parts of the chromium compound are mixed
with 66 parts nitrate or nitrite of potash, or 55½ parts nitrate or nitrite
of soda, and with 100 parts dolomite to form chromate of potash or
soda and chromate of lime.
In a sixth process 100 parts of the chromium compound are mixed
with 132 parts nitrate or nitrite of potash, or 111 parts nitrate or nitrite
of soda, and with 150 parts dolomite to form chromate of potash or
soda.
In a seventh process 100 parts of the chromium compound are mixed
with 66 parts nitrate or nitrite of potash, or 55 parts nitrate or nitrite
of soda, and 57 parts sulphate of potash, or 46 parts sulphate of soda,
and with 150 parts dolomite to form chromate of potash or soda and
sulphate of lime.
In an eighth process 100 parts of the chromium compound are mixed
with 105 parts nitrate or nitrite of lime, and with 113 parts sulphate
of potash or 94 parts sulphate of soda and with 150 parts dolomite to
form chromate of potash or soda and sulphate of lime.
In a ninth process 100 parts of the chromium compound are mixed
with 58 parts nitrate or nitrite of lime, and with 56 parts sulphate of
potash or 47 parts sulphate of soda, and with 100 parts dolomite to
form chromate of potash or soda, chromate of lime, and sulphate of
lime.

page_text: In a tenth process 100 parts of the chromium compound are mixed
and fused with 113 parts sulphate of potash or 94 parts sulphate of
soda, or 89 parts sulphate of lime or 154 parts sulphate of barium, or
120 parts sulphate of strontium and 60 parts carbon, and afterwards
the fused mass is ground and mixed with 150 parts dolomite.
In an eleventh process 100 parts of the chromium compound aro
mixed and fused with 71 parts sulphide of potassium or 52 parts
sulphide of sodium, or 48 parts sulphide of calcium or 111 parts
sulphide of barium, or 73 parts sulphide of strontium, and afterwards
the fused mass is ground and mixed with 150 parts dolomite.
In a twelfth process 100 parts of the chromium compound are mixed
with 103 parts sulphite of potash or 84 parts sulphite of soda, and with
150 parts dolomite to form chromate of potash or soda.
In a thirteenth process 100 parts of the chromium compound are
mixed with 97 parts of chloride of potassium or 76 parts of chloride 1
of sodium, and with 100 parts of dolomite to form chromate of potash or
soda.
In all the processes the proportions of the ingredients may be modified
to some extent without inconvenience. For the dolomite a similar
compound may be substituted by mixing magnesite (carbonate of 2
magnesia) and carbonate of lime, or any other suitable compound of
magnesia and lime may be used in any of the processes. The dolomite
or compound of lime and magnesia may be freed or partially freed from
carbonic acid before being mixed with the other ingredients. When the
chromium ore or compound contains a different proportion from that 2
mentioned of sesquioxide of chromium, the proportions of the other
ingredients should be modified accordingly.
The several ingredients are by preference ground together or mixed in
a ground state, or any soluble ingredients may be added in solution.
The complete mixture comprising the dolomite or its equivalent is 3
subjected in the usual way to the heat necessary for effecting the
oxidation, and in the case of the thirteenth process steam and atmo-
spheric air aro passed in contact with the mixture whilst it is being
heated, the mixture being either spread on the hearth of the furnace or
heating chamber and repeatedly stirred, or being made up with clay or 3
other suitable adhesive substance into balls or bricks, which, when piled

page_text: together, leave interstices between them for the passage of the steam
and air. Any suitable oxidiser may be substituted for the air.
Having thus particularly described my said Invention, and the manner
of performing the same, I have to state that what I believe to be novel
and original, and claim as secured to me by the herein-before in part
recited Letters Patent is,-
1. The using of a mixture or compound of lime and magnesia in
processes for obtaining chromates, substantially as and for the purposes
herein-before described.
2. The making of chromates in the same manner, substantially as in
any of the processes herein-before described.
In witness whereof, I, the said Joseph Townsend, have here-
unto set my hand and seal, this Thirty-first day of May, in the
year of our Lord One thousand eight hundred and seventy-
six.