IMPROVEMENTS IN THE MANUFACTURE OF CHROMATES AND BICHROMATES
Year: 1884

page_text: I WILLIAM JOHN ALEXANDER DONALD of Number Two Belgrave Terrace,
Hillhead, Glasgow Secretary and Commercial Manager of The Eglinton Chemical
Company Limited Glasgow in the County of Lanark Scotland do hereby declare
the nature of my invention for " IMPROVEMENTS IN THE MANUFACTURE OF
CHROMATES AND BICHROMATES" to be as follows:-
My invention has for its object to obtain chromate and bichromate of ammonia
I begin by making chromate of soda by preference in the manner described in my
application No 4811 bearing even date with the present. I then dissolve sulphate
of ammonia and treat the same with chloride of calcium or chloride of barium.
The result of this treatment is the formation of chloride of ammonia and sulphate
of calcium or sulphate of barium. I afterwards treat the chromate of soda with
the chloride of ammonia so obtained with the result that chromate of ammonia and
chloride of sodium are produced. The latter may be eliminated at this stage by
evaporating the liquors or at a later stage after bichromate of ammonia is formed:
To convert the chromate of ammonia into bichromate of ammonia I treat the
same with hydrochloric acid, sulphuric acid, oxalic acid, carbonic acid or other
suitable acid. The bichromate is separated from the liquors by evaporation at a
lower or higher temperature. The other salts of ammonia become available for the
formation of chromate of ammonia and the process is thus a continuous one.
Dated this 13th day of March 1884

page_text: I WILLIAM JOHN ALEXANDER DONALD of number two Belgrave Terrace,
Hillhead Glasgow Secretary and Commercial Manager of The Eglinton Chemical
Company Limited Glasgow in the County of Lanark Scotland do hereby declare
the nature of my invention for "IMPROVEMENTS IN THE MANUFACTURE OF
CHROMATES AND BICHROMATES" and in what manner the same is to be performed
to be particularly described and ascertained in and by the following statement:—
My Invention has for its object to obtain chromate and bichromate of ammonia,
I begin by making chromate of soda by preference in the manner described in my
application No 4811 bearing even date with the present. I then dissolve sulphate
of ammonia and treat the same with chloride of calcium or chloride of barium.
The result of this treatment is the formation of chloride of ammonia and sulphate
of calcium or sulphate of barium. I afterwards treat the chromate of soda with
the chloride of ammonia so obtained with the result that chromate of ammonia
and chloride of sodium. are produced. The latter may be eliminated at this stage
by evaporating the liquors or at a later stage after bichromate of ammonia is
formed.
To convert the chromate of ammonia into bichromate of ammonia I treat the
same with hydrochloric acid, sulphuric acid, oxalic acid, carbonic acid or other
suitable acid. The bichromate is separated from the liquors by evaporation at a
lower or higher temperature.
The other salts of ammonia become available for the formation of chromate of
ammonia and the process is thus a continuous one.
Having now particularly described and ascertained 'the nature of my said
Invention, and in what manner the same is to be performed, I declare that what
I claim is
1. The process herein described for the production of chromate of ammonia
consisting in the treatment of sulphate of ammonia with chloride of calcium or
chloride of barium and then employing the resulting chloride of ammonia to
decompose chromate of soda thereby obtaining a mixed solution of chromate of
ammonia and chloride of sodium from which when concentrated the latter is
deposited and easily removed.
2. The improvement herein described in the manufacture of chromates and
bichromates of ammonia consisting in treating chromate of ammonia with hydro-
chloric or other acid then separating the bichromate from the other ammonia salt
by evaporation and employing the latter in the conversion of chromate of soda into
chromate of ammonia substantially as described.
3. The processes for the, manufacture of chromate and bichromate of ammonia
substantially as described.
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