IMPROVEMENTS IN THE MANUFACTURE OF BICHROMATES A
Year: 1882

page_text: "
LETTERS PATENT to John Henry Johnson of 47 Lincolns Inn Fields in the
County of Middlesex Gentleman for an Invention of "IMPROVEMENTS IN
THE MANUFACTURE OF BICHROMATES A communication to him from
Otto Neuhaus, Adolf Neuhaus and Albert Neuhaus persons resident at
Elberfeld, in the Empire of Germany
PROVISIONAL SPECIFICATION left by the said John Henry Johnson at the
Office of the Commissioners of Patents on the 18th December 1882.
"
JOHN HENRY JOHNSON of 47 Lincolns Inn Fields in the County of Middlesex
Gentleman "IMPROVEMENTS IN THE MANUFACTURE OF BICHROMATES a com-
munication from Otto Neuhaus, Adolf Neuhaus and Albert Neuhaus persons
resident at Elberfeld, in the Empire of Germany,
The invention consists in the manufacture of bichromates of Potash, Soda,
Calcium, Barium and Magnesium, from their chromates, by adding, under pressure
(and heat if necessary) carbonic acid to them and. thus formning bichromates and
carbonates of Potash, soda, calcium, Barium and Magnesium.
In making Bichromate of Potash according to this Invention the neutral liquor
of Chromate of Potash, after the same has been sufficiently concentrated by
evaporation and has become cool, is pumped into a large boiler, which is sufficiently
strong to stand a pressure of five or more atmospheres, and which contains a
stirrer or agitator-Carbonic acid is passed into this boiler, containing the neutral
liquor, by preference at a pressure from three to five atmospheres and under
continual stirring-The neutral liquor is thus converted into the bichromate and
Hydropotassic Carbonate 2 (K, Cr O) + 2 (CO₂) + HO₂ =K, Cг, 07 + 2 (KH C.O₂)
The bichromate of potash formed is in small crystals, from which the Hydro-
potassic Carbonate, which is in solution, is separated by a Centrifugal machine-In
a similar manner in making Bichromate of Soda according to this Invention
Bichromate of Soda and Hydrosodic Carbonate are forined by the action of
Carbonic Acid on Neutral Chromate of Soda 2 (Na₂ Cr O.) + CỔ₂ + H₂O = Nag

page_text: Cr, 0, x 2 (Na,+ CO₂). In this case Hydrosodic Carbonate precipitates and
the liquor containing Bichromate of Soda is separated from it by a Centrifugal
machine.
The Bichromates of Calcium and Barium are formed by heating the neutral
liquors of Chromates of Calcium and Barium in a boiler as above and pressing
Carbonic Acid into it-In this manner Bichromates of Calcium or Barium remain
in solution, when the liquor is cooled, and Carbonates of Calcium or Barium are
precipitated 2 (Ca Cr O₁) + C.O₂ = Ca Cr, 0, + Ca C.Os
2 (Ba Cr O+ C.O₂-
=
Ba Cr. O, Ba C.O,
The Bichromate of Magnesia is obtained from Chromate of Calcium by adding
Carbonate (or Caustic) Magnesia, and adding to this mixture, after heating,
Carbonic Acid, Calcium Bichromate is formed and this is converted by the
Carbonate (or Caustic) Magnesia into Bichromate of Magnesia and Carbonate of
Calcium 2 (Ca Cr O₁) + Mg C.O, + CO₂ = Mg Crg 0, +2 (Ca C.O₂)
r
SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said John Henry Johnson in the Great Seal Patent Office on the
4th June 1883.
JOHN HENRY JOHNSON of 47 Lincoln's Inn Fields in the County of Middlesex
Gentleman "IMPROVEMENTS IN THE MANUFACTURE OF BICHROMATES" a com-.
munication to ine from Otto Neuhaus, Adolf Neuhaus, and Albert Neuhaus, persons
resident at Elberfeld in the Empire of Germany
This Invention consists in the manufacture of bichromates of Potash, Soda,
Calcium, Barium and Magnesium from their Chromates by adding under pressure
(and heat if necessary) Carbonic Acid to the said Chromates and thus forming
bichromates and Carbonates of Potash, Soda, Calcium, Barium and Magnesium.
In making Bichromate of Potash according to this Invention the neutral liquor
of Chromate of Potash after the same has been sufficiently concentrated by
evaporation and has become cool is pumped into a large boiler which is sufficiently
strong to stand a pressure of five or more atmospheres and which contains a stirrer
or agitator. Carbonic Acid is passed into this boiler containing the neutral liquor
by preference at a pressure of from three to five atmospheres and under continual
stirring. The neutral liquor is thus converted into the bichromate and hydropotassic
Carbonate 2 (K, Cr O₁) + 2 (CO) + H2O = K, Cr, O, + 2 (KH CO₂).'
The bichromate of Potash formed is in small Crystals from which the Hydro-
potassic Carbonate, which is in solution is separated by a Centrifugal Machine. In
a similar manner in making bichromate of Soda, according to this Invention
bichromate of Soda and Hydrosodic Carbonate are formed by the action of
Carbonic acid on Neutral Chromate of Soda. 2 (Na, CгO) + CO2 + H2O = Nag
Cr, O + 2 (Na + CO₂). In this case Hydrosodic Carbonate precipitates and

page_text: the liquor containing bichromate of Soda is separated from it by a centrifugal
machine.
The bichromates of Calcium and Barium are formed by heating the neutral
liquors of Chromates of Calcium and Barium in a Boiler as hereinbefore described
and passing Carbonic acid into it. In this manner bichromates of Calcium or
Barium remain in solution when the liquor is cooled and Carbonates of Calcium or
barium are precipitated.
2 (Ca Cr O₁) + CO₂
2 (Ba Cr O) CO₂
= Ca Cr, O, + Ca Cos
=
Ba Cr, 0, + Ba CO,
Bichromate of Magnesia is obtained from Chromate of Calcium by adding
Carbonate (or Caustic) Magnesium and adding to this mixture after heating
Carbonic Acid Calcium bichromate is formed and this is converted by the
Carbonate (or Caustic) Magnesia into bichromate of Magnesia and Carbonate of
Calcium.
2 (Ca Cr O₁) + Mg CO, + CO₂ = Mg Cr, O, + 2 (Ca CO₂).
Having now described and particularly ascertained the nature of the said
Invention and the manner in which the same is or may be used or carried into
effect I would observe in conclusion that what I consider to be novel and
original and therefore claim as the Invention secured to me by the hereinbefore in
part recited Letters Patent is :-
The manufacture of bichromates of Potash, Soda, Calcium, Barium, and Magnesia
from their Chromates by adding under pressure (and heat if necessary) Carbonic
Acid as herein before described.
In witness whereof I the said John Henry Johnson have to this my
Specification set my hand and seal this twenty ninth day of May One
thousand eight hundred and eighty three.
זגYANICA
HENRI
JOHNSON (L.S)