IMPROVEMENTS IN MANUFACTURE OF SULPHURIC ACID, NITRIC ACID, OXALIC ACID, CHLORINE AND SULPHUR
Year: 1848

page_text: TO ALL TO WHOM THESE PRESENTS SHALL COME, we, ALEXANDER
M'DOUGAL, of Longsight, near Manchester, Chemist, and HENRY RAWSON, of
Manchester, Agent, send greeting.
WHEREAS Her present most Excellent Majesty Queen Victoria, by Her
Royal Letters Patent under the Great Seal of the United Kingdom of Great
Britain and Ireland, bearing date at Westminster, the Twenty-first day of
November, One thousand eight hundred and forty-eight, in the twelfth year of
Her reign, did, for Herself, Her heirs, and successors, give and grant unto us,
the said Alexander M'Dougal and Henry Rawson, our exors, admors, and
assigns, Her especial licence, full power, sole privilege and authority, that we,.
the said Alexander M'Dougal and Henry Rawson, our exors, admors, and
assigns, or such others as we, the said Alexander M'Dougal and Henry
Rawson, our exors, admors, or assigns, should at any time agree with, and no
others, from time to time and at all times during the term of years therein
expressed, should and lawfully might make, use, exercise, and vend, within
England, Wales, and the Town of Berwick-upon-Tweed, in the Islands of
Jersey, Guernsey, Alderney, Sark, and Man, and also in all Her said Majesty's
Colonies and Plantations abroad, our Invention of "IMPROVEMENTS IN
MANUFACTURE OF SULPHURIC ACID, NITRIC ACID, OXALIC ACID, CHLORINE AND
SULPHUR;" in which said Letters Patent is contained a proviso, that we, the
said Alexander M'Dougal and Henry Rawson, or one of us, should cause a
particular description of the nature of our said Invention, and in what manner
the same is to be performed, by an instrument in writing under our hands and

page_text: seals, or under the hand and seal of one of us, to be inrolled in Her Majesty's
High Court of Chancery within six calendar months next and immediately
after the date of the said in part recited Letters Patent, as in and by the
same, reference being thereunto had, will more fully and at large appear.
NOW KNOW YE, that in compliance with the said proviso, we, the said
Alexander M'Dougal and Henry Rawson, do hereby declare that the nature
of our said Invention, and the manner in which the same is to be performed,
are fully described and ascertained in and by the following statement thereof,
that is to say:-
In order that our said Invention may be the better understood we shall
first describe our improvements in the manufacture of oxalic and nitric acid.
One is the substitution of rice for sugar or starch in the manufacture of oxalic
acid; the other is our method of treating the nitrous gas or fumes which are
given off from the action of nitric acid upon the sugar, starch, rice, or other
organic substances used for the manufacture of oxalic acid. We convey these
fumes into a vessel containing water by a pipe dipping below the surface of the
water. We permit air to enter into this vessel and to mix with the gas which
bubbles through the water. This mixture of air and nitrous gas we draw by
a pneumatic apparatus through a series of vessels similar to the first, each con-
taining a tube dipping into the liquid, and another tube or pipe attached to its
top to connect it with the next vessel, thus making the nitrous gas to pass
alternately into air and water, by which means nitrous gas is converted into
nitric acid. The reaction which ensues may be best explained by the use of
chemical symbols. Thus, when 3 No. 4 is passed into water at a temperature
of 100° Fahrenheit or upwards, 2 No. 5 + No. 2 results, the 2 No. 5 (i.e., two
atoms of nitric acid) remain in solution, while the No. 2, which is incondensible
gas, bubbles through the liquid and mixes with the air in the vessel above the
liquid; it instantly takes two atoms of oxygen from the air, and becomes
No. 4, which passing again through the liquid becomes nitric acid and nitrous
gas as before, and thus nearly the whole of the nitrous fumes or gas is
reconverted into nitric acid. The nitric acid thus obtained may be used again
for the manufacture of oxalic acid, or for any other purpose to which nitric
acid is applied. When the temperature of the liquid into which the nitrous
gas is passed is much under 100° Fahrenheit a slightly different but equally
beneficial reaction ensues. There are several chemical processes in which
nitrous gas is given off; to each of these the above process is applicable.
We claim, under this part of our Invention, the use of rice in the manu-
facture of oxalic acid.
We claim also the manufacture of nitric acid by passing the lower oxides

page_text: of nitrogen alternately into water or an aqueous solution of acid and air con-
taining oxygen, whether these lower oxides may be obtained in the manufacture
of oxalic or in any other process.
Second, in our improved method of manufacturing sulphuric acid we use a
series of vessels similar to that described in the first part of this Invention,
only that the first vessel of the series is connected with a sulphur burner. The
mode of working is to fill the first vessel one-third full of nitric acid and all the
others one-third full of water to charge the burner with sulphur, and then to
put in motion the pneumatic apparatus with the last vessel of the series; air is
thus drawn over the ignited sulphur, so that sulphurous acid and air pass into
a solution of nitric acid in the first vessel, when a portion of the sulphurous
acid is converted into sulphuric acid at the expence of the nitric acid, when
the uncondensed sulphurous acid passes with the air and the nitrous gas
in the next vessel, and so, as in the first part of the Invention, they
pass alternately into water and air till the processes of oxidation and con-
densation are completed. When the working has been continued some
time we find that the nitric acid has entirely passed from the first vessel,
and we have in its place sulphuric acid nearly pure; the same would
take place with each of the other vessels of the series if the nitric acid
which has been condensed in the vessels lower in the series was not again
returned to the higher ones, so that when we find the first vessel is exhausted
of its nitric acid we remove the sulphuric which it contains, and supply it
again with nitric acid obtained from vessels lower in the series. We thus
produce sulphuric acid without the loss of any nitric acid, as the lower oxides
of nitrogen given off in the oxidation of sulphurous acid are again converted
into the higher oxides, and again used for the conversion of sulphurous into
sulphuric acid.
.
Under this part of our Invention we claim the manufacture of sulphuric
acid by the process above described.
The next part of our Invention relates to the manufacture of chlorine, in
which we treat any of the chromates or bichromates with hydrochloric acid,
either in its free or nascent state, chlorine is given off, and a chloride or sesque-
chloride of chromium and a chloride of the base of the chrome salt is formed.
We then treat these latter products with nitric acid and distil off the hydro-
chloric acid, when we obtain nitrates of chrome and of the base of the original
chrome salt. These nitrates we expose to heat, when the lower oxides of
nitrogen are given off, which we oxidize and condense, as described in the first
part of this Invention. By the action of heat upon these nitrates, we also
obtain, after the oxides of nitrogen have been driven off, the chromate or

page_text: bichromate first employed, which may be used for the production of chlorine
as before, of the chromates or bichromates, for the above process we prefer
the chromate of lime.
Our claim is for the use of the chromates or bichromates in the manufacture
of chlorine in connection with the use of nitric acid for the reconversion of
the lye products into the chromate or bichromate originally employed.
Our improvement in the manufacture of sulphur consists in passing sul-
phuretted hydrogen through a heated tube, by which the gas is decomposed,
sulphur being deposited and hydrogen going off.
Our claim is for the decomposition of sulphuretted hydrogen by heat
from whatever source obtained.
In witness whereof, I, the said Alexander M'Dougal, have hereunto set
my hand and seal, this Eighteenth day of May, in the year of our Lord
One thousand eight hundred and forty-nine.
Enrolled the Twenty-first day of May, in the year of our Lord One
thousand eight hundred and forty-nine.