IMPROVEMENTS IN THE MANUFACTURE OF SULPHURIC ACID
Year: 1875

page_text: LETTERS PATENT to Charles Frederick Burnard, of the Plymouth
Chemical Works, Plymouth, in the County of Devon, Manu-
facturing Chemist, for the Invention of "IMPROVEMENTS IN THE
Sealed the 6th October 1875, and dated the 14th August 1875.
PROVISIONAL SPECIFICATION left by the said Charles Frederick
Burnard at the Office of the Commissioners of Patents, with his
Petition, on the 14th August 1875.
I, CHARLES FREDERICK BURNARD, of the Plymouth Chemical Works,
Plymouth, in the County of Devon, Manufacturing Chemist, do hereby
declare the nature of the said Invention for "IMPROVEMENTS IN THE
MANUFACTURE OF SULPHURIC ACID," to be as follows:-
In the manufacture of sulphuric acid as now generally followed the
nitrates employed for the supply of the nitric or nitrous acid vapours or
gases are decomposed by the aid of sulphuric acid in pots or ovens,
usually of cast iron, which are so placed as to be heated by the current
of gases proceeding from the burning brimstone or pyrites, and that

page_text: then the said acid vapours from the said pots or ovens mingle and
proceed together with the sulphurous acid from the burners and kilns,
either directly to the lead or other chambers, or, as is mostly the case, to
the denitrating or "Glover's" towers.
Now it is well known that this method of using the nitrates is inter-
mittent, inconvenient, and wasteful, and that morcover it falls very far
short of furnishing the full value of work which the quantity of nitrates
employed represents, by reason of the partial breaking up of the nitrous
acid vapours or gases into simpler and non-effective forms under the
influence of the high temperature necessarily existing in the flues and
other parts.
Now in this my Invention I do not decompose the nitrates in pots or
ovens, nor do I permit the nitrous acid vapours or gases to commingle
with the sulphurous acid gases of the burning brimstone or pyrites
before the entry of such gases into the chambers or denitrating towers,
but I introduce the requisite quantity of the nitrate (say nitrate of soda)
directly into the circulatory system of the process, that is to say, cither
into the acid on the floor of the chamber or chambers, or into its or
their atmosphere or atmospheres, or into the absorbent or nitrating
tower, or into the denitrating tower, or into any intermediate vessel or
vessels in connection therewith, and cither in a dry powdery state or in
the state in which it usually exists in commerce, or in a state of
solution, that is to say, if it be the practice at any given acid works to
pass all the acid made through the denitrating towers, then the nitrate
of soda or other nitrate may be applied to the acid on the floor of the
chambers, preferably on that of the first, by any suitable means, but I
prefer to do so with the nitrate in solution in water, and the "flow" or
"drip" so regulated that it shall be constant and not intermittent.
In
its application to the atmosphere of the chambers I dissolve the nitrato
in water and inject it by any of the well-known methods through the
agency of steam or otherwise. But if it be inconvenient to pass all the
acid made through the denitrating or "Glover's" towers, then the above
described methods must not be employed, and the nitrate must be intro-
duced into the system, cither into the absorbent towers or into the
denitrating tower, or into any other vessel or vessels, whether open or
closed, or part or parts of the apparata or system which may appear
most convenient thereto. In whichever way applied, the nitrate if not
perfectly decomposed before it reaches the denitrating towers, its decom-

page_text: position is there quickly and perfectly effected, and in either case it is
decomposed and yields its nitrogen, acids, and oxides under the most
favourable conditions.
I would here state that by the practice of this my Invention the
residuum of sulphate or bisulphate, say of soda, is for the time lost in the
process, but this is a very small matter, it being relatively of but little
commercial value; and as the principal consumption of sulphuric acid
is in the manufacture of sulphate of soda and of manures, so in the
manufacture of sulphate of soda it is all recovered, and in the manu-
facture of manures its manurial value is quite equal to the amount of
the apparent loss.
I would here remark that although I have in the above description
referred to nitrating and denitrating towers or "Glover's" towers, my
Invention is equally applicable to cases where substitutes or equivalents
are employed for such parts.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Charles Frederick Burnard in the Great Seal
Patent Office on the 14th February 1876.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, CHARLES
FREDERICK BURNARD, of the Plymouth Chemical Works, Plymouth, in
the County of Devon, Manufacturing Chemist, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Fourteenth day of August, 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 Charles Frederick Burnard, Her
special license that I, the said Charles Frederick Burnard, my executors,
administrators, and assigns, or such others as I, the said Charles
Frederick Burnard, 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 make, use, exercise, and vend, within the United Kingdom of
Great Britain and Ireland, the Channel Islands, and Isle of Man,
an Invention for "IMPROVEMENTS IN THE MANUFACTURE OF SULPHURIC ACID,"

page_text: upon the condition (amongst others) that I, the said Charles Frederick
Burnard, 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 Charles Frederick Burnard, do
hereby declare the nature of the said Invention, and in what manner
the same is to be performed, to be particularly described and ascer-
tained in and by the following statement thereof, that is to say:—
In the manufacture of sulphuric acid as now generally followed the
nitrates employed for the supply of the nitric or nitrous acid vapours
or gases are decomposed by the aid of sulphuric acid in pots or ovens,
usually of cast iron, which are so placed as to be heated by the current
of gases proceeding from the burning brimstone or pyrites, and that
then the said acid vapours from the said pots or ovens mingle and
proceed together with the sulphurous acid from the burners and kilns,
either directly to the lead or other chambers, or, as is mostly the case,
to the denitrating or
66 Glover's" towers.
Now it is well known that this method of using the nitrates, is
intermittent, inconvenient, and wasteful, and that moreover it falls
very far short of furnishing the full value of work which the quantity
of nitrates employed represents by reason of the partial breaking up
of the nitrous acid vapours or gases into simpler and non-effective
forms under the influence of the high temperature necessarily existing
in the flues and other parts.
Now in this my Invention I do not decompose the nitrates in pots or
ovens, nor do I permit the nitrous acid vapours or gases to commingle
with the sulphurous acid gases of the burning brimstone or pyrites
before the entry of such gases into the chambers or denitrating towers,
but I introduce the requisite quantity of the nitrate (say nitrate of
soda) directly into the circulatory system of the process, that is to say,
cither into the acid on the floor of the chamber or chambers, or into
its or their atmosphere or atmospheres, or into the absorbent or nitrating
tower, or into the denitrating tower, or into any intermediate vessel or
vessels in connection therewith, and either in a dry powdery state or in

page_text: the state in which it usually exists in commerce, or in a state of solution,
that is to say, if it be the practice at any given acid works to pass all
the acid made through the denitrating towers, then the nitrate of soda
or other nitrate may be applied to the acid on the floor of the chambers,
preferably on that of the first, by any suitable means, but I prefer to
do so with the nitrate in solution in water, and the "flow" or "drip" so
regulated that it shall be constant and not intermittent. In its appli-
cation to the atmosphere of the chambers I dissolve the nitrate in water
and inject it by any of the well-known methods through the agency of
steam or otherwise. But if it be inconvenient to pass all the acid made
through the denitrating or "Glover's" towers, then the above described
methods must not be employed, and in lieu thereof the nitrate must be
introduced into the system, either into the absorbent tower or into the
denitrating tower, or into any other vessel or vessels, whether open or
closed, or part or parts of the apparata or system which may appear
most convenient thereto. In whichever way applied, the nitrate if not
perfectly decomposed before it reaches the denitrating towers, its
decomposition is there quickly and perfectly effected, and in either
case it is decomposed and yields its nitrogen, acids, and oxides under the
most favorable conditions.
I would here state that by the practice of this my Invention the
residuum of sulphate or bisulphate, say of soda, is for the time lost in
the process, but this is a very small matter, it being relatively of but
little commercial value; and as the principal consumption of sulphuric
acid is in the manufacture of sulphate of soda and of manures, so in the
manufacture of sulphate of soda it is all recovered, and in the manu-
facture of manures its manurial value is quite equal to the amount of
the apparent loss.
I would here remark that although I have in the above description
referred to nitrating and denitrating towers, or
Glover's" towers, my
Invention is equally applicable to cases where substitutes or equivalents
are employed for such parts.
The introduction of the nitrate may be made in any way, as already
set forth. If introduced into the chamber bottom or bottoms, then if
the whole of the acid be pumped through the denitrating tower or
towers, it is a matter of indifference into which of the chamber bottoms
it is introduced, but I prefer it to be so introduced into the first of the

page_text: series, but if the whole of the acid made be not so pumped, then I
recommend the nitrate to be introduced into such chamber bottom or
bottoms as may in the order of the working be selected for furnishing
the acid for being so pumped, taking such precautions as may be
necessary for preventing the acid from such selected chamber bottom or
bottoms from flowing into any of the bottoms of the non-selected
chambers, but it is not necessary to exclude or provent the acid of the
non-selected chamber bottoms from flowing into the bottom or bottoms
of the selected chamber or chambers. Into such selected chamber
bottom or bottoms the nitrate may be made to flow in a state of solution
from a tank or tanks and in such regulated quantity as may in the
working be deemed necessary.
If it be elected to drive the solution of nitrate into the atmosphere of
the selected chamber or chambers, then it may be effected by means of a
Giffard's injector, or any modification thereof, or by steam pressure in
a small boiler, set either with an independent fire or so that it be heated
by the flue of the large steam boiler usually employed for furnishing
steam in the acid manufacture process. The solution of nitrate may be
forced into such small boiler by a Giffard's injector, and then the nitrate
solution in the said small boiler can be forced up through suitable
nozzles into the chamber atmosphere or atmospheres through a pipe
dipping some distance under the solution of nitrate, either by its own
steam pressure or by establishing and opening a connection between
the steam of the larger boiler and that of the smaller one. The nozzle or
nozzles for delivering the nitrate solution into the chamber atmosphere
may be so combined with the steam supply at such part in any well-
known way that the steam shall drive in the nitrate solution before it so
as to vapourize and completely disseminate it. So far as the supply of
the nitrate is concerned one such injector will usually be found sufficient,
and it may be fixed in any given position, but I recommend it to be
placed at the end of the first chamber near the entrance of the sul-
phurous acid gases.

page_text: Fourth. In the manufacture of sulphuric acid the introduction of
the nitrate into the atmosphere or atmospheres of the chamber or
chambers, in conjunction with steam or otherwise.
Fifth. In the manufacture of sulphuric acid the application of the
nitrate in solution or otherwise into any part which may direct or lead
it finally into the denitrating tower or towers, or any substitute
therefor.
In witness whereof, I, the said Charles Frederick Burnard, have
hereunto set my hand and seal, this Fifth day of February,
in the year of our Lord One thousand eight hundred and seventy-
six.