AN IMPROVED METHOD OF, & APPARATUS FOR, EXTRACTING AMMONIA FROM FURNACE GASES to be as follows
Year: 1884

page_text: I, WILLIAM ROBERT LAKE, of the firm of Haseltine, Lake & Co, Patent Agents,
Southampton Buildings, in the County of Middlesex do hereby declare the nature
of said invention for "AN IMPROVED METHOD OF, & APPARATUS FOR, EXTRACTING
AMMONIA FROM FURNACE GASES to be as follows:-.
This invention relates to the manufacture of ammonia and to apparatus therefor.
Endeavours have been made to extract ammonia from the waste gases of furnaces
and the like, but it was generally found that the means employed obstructed the
draught in the flues. There was also no substance known which could be economi-
cally employed for absorbing the aminonia.
The object of this invention is to overcome these difficulties and it consists
essentially in the provision of suitable apparatus hereinafter described and in the
employment of chloride of calcium, which is of small commercial value, for absorbing
the ammonia.
According to the said invention I arrango at the extremity of the flue through
which the products of combustion from any furnace, oven or the like pass, a pipe
connected with which is a second transverse pipe from which extend a series of
smaller tubes. These small tubes pass through a receptacle supplied with cold
water through a cock situated at the lower part thereof. The heated water runs
out at the upper part of the said receptacle and at the opposite end to which it
entered. The small pipes convey the gases to a second metal receptacle which
serves as a sort of gasometer and from which an exhaust pump draws its supply.
A cock permits the condensed vapors to be extracted. A manometer on the said
second receptacle constantly indicates the pressure inside the same, which pressure
can be regulated by increasing or decreasing the speed of the exhaustivo pump.
Two pipes convey the gases to the cylinder of a blowing machine or fan and two
other pipes lead the gases forward as they are blown by the fan.
The said fan is rotated in the ordinary manner by a steam engine. The last
mentioned pipes convey the gases to a long transverse pipe upon which are fixed
a series of smaller pipes which enter a vessel containing a solution of chloride of
ro

page_text: calcium into which solution portions of the said pipes dip equal to half the height
of the liquid. In order to ensure the complete extraction of the ammonia from
the sesqui-carbonate, especially when the liquid is nearly saturated, it is necessary
to have at least another vessel containing a pure solution of chloride of calcium
into which the gases pass after leaving the first vessel.
When the solution in the first vessel is saturated it is drawn off by means of a
pipe provided with a cock and replaced by that of the second vessel, a fresh
solution being introduced in the latter vessel, the operation being repeated when
required.
The gases proceed from the second vessel into a third vessel lined with lead and
containing the sulphuric acid which is designed to decompose the hydro-cyanate of
ammonia contained in the gases and combine with the same.
In extensive operations which should proceed with great regularity, it will be
advantageous to have two complete sets of chloride of calcium vessels. Lastly
the gases deprived of all the ammonia which they contained proceed through
one or two large pipes into a flue or chimney.
This process of treating waste gases may be used in connection with "Knab's "
coke ovens in which only tars and aminoniacal waters which are deposited
instantaneously are collected as the gas on leaving these ovens still contains a
quantity of ammonia. No great outlay is necessary to obtain this double result
since the extractors are already at hand as well as the pipes and a large gasometer
serving as a reservoir.
It must be understood that this method is applicable to all coke ovens from the
gaseous products of which the ammonia is not extracted or only partially
extracted.
Tlie same applies to all-furnaces-heated-with-coal, wood or peat-in which the
ammonia of the products of combustion is also lost.
It will be seen that this invention is based upon a complete series of mechanical
and chemical operations which may individually have been applied; or are applied
partially, but under different conditions.
n
A1 1004
HASELTINE, LAKE & Co.,
For the Applicant.

page_text: COMPLETE SPECIFICATION.
I, WILLIAM ROBERT LAKE, of the firm of Haseltine, Lake, & Co, Patent
Agents, Southampton Buildings, in the County of Middlesex do hereby declare
the nature of my invention for "AN IMPROVED METHOD OF AND APPARATUS FOR
EXTRACTING AMMONIA FROM FURNACE GASES "
and in what manner the same is to
be performed, to be particularly described and ascertained in and by the following
statement:
This invention relates to the manufacture of ammonia, and to apparatus therefor.
Ammonia is of very great value, not only for agricultural purposes but also in
various industrial manufactures, amongst which may be mentioned as one of the
most important, the preparation of carbonate of soda by means of bi-carbonate of
ammonia. If ammoniacal salts could be obtained at a cheaper rate than heretofore,.
the sale thereof, for agricultural purposes, would probably be very large indeed..
Ammonia is scattered throughout nature, and experimenters have even been able
to detect it and quantitatively analyse it in the atmosphere, which on an average
may contain one millionth of its weight of ammonia in the form of Sesqui-carbonate
or of nitrate of ammonia. This quantity which appears, at first, very minute,,
becomes highly important when it is ascertained by calculation that each hectare of
land supports a weight of one hundred and three million kilogrammes of air. The
ammonia contained therein is constantly being carried to the surface of the earth
by rain, snow and such like, and is likewise being returned constantly to the
atmosphere in consequence of the chemical phenomena which take place upon the
surface of the earth. Ammonia is absorbed by plants but restored to the atmos-
phere by reason of the decomposition of vegetable and animal matters. One of the
sources which supplies the atmosphere with ammonia proceeds from the combustion
of wood, peat, coal and the like. It has been found from experiments that in
Germany, the combustion of coal alone supplies the atmosphere annually through
chimneys, with an amount of ammonia valued, according to the actual price of
ammoniacal salts, at two hundred and twenty five millions of francs.
About fifteen years ago attempts were made to obtain the ammonia thus lost but
such trials were abandoned on account of the impediments caused by the means
employed to the draught of the chimneys, and also because of the want of suitable
substances necessary for the absorption of the ammonia.
The chief reason of the failure however is that the question was merely considered
as the solution of a chemical problem, whereas on the contrary the mechanical part
of the said question was an important factor therein. On the other hand the
chemical question had not been sufficiently studied, and it is to a deep study of both
the mechanical and chemical parts of the question that the communicators of this
invention owe the solution of the problem.
In the products resulting from the combustion of coal, ammonia is found mostly
in the form of a sesqui-carbonate,

page_text: hydrocyanate as the ammonia in contact with coal heated to redness causes the
formation of this product.
(N H³) + 2 C = (N H³ + Cy H + 2 H)
The hydrocyanate of ammonia Cy H, N HS has for its well known elementary
composition CNH, NH³. Ammonia is also met with in the products resulting
from the combustion of sulphite of ammonia proceeding from the decomposition
of hydro-sulphate. But, as before stated, the greatest part of the ammonia is
generated in the form of sesqui carbonate which, however, does not prevent the
extraction of the other ammoniacal products when it is desired to achieve a
complete industrial success.
The mechanical question is, as above stated, an important factor in the solution
of the problem; without mechanical means no results are possible.
Men who have paid attention to the question relating to the loss of the ammonia
produced by the combustion of coal agree to consider it as one of great importance.
This loss has been-estimated at the considerable average amount of 10 kilogrammes
per ton of coal that is including all the ammoniacal combinations. By means of
this invention this loss is reduced to five kilos of N H³ per ton of coal.
In order to extract these five kilogrammes and cause them to be absorbed there
are two problems to solve, first the practical mode of effecting this extraction
without interfering with the draught necessary for the combustion, that is to say
the mechanical part of the process; and secondly the selection of economical and
industrial substances capable of absorbing the ammonia, that is to say the chemical
part of the process. Moreover, it is obvious that the locality and circumstances
must be such as to furnish the most economical results especially with reference to
the mechanical part of the process.
With reference to the mechanical part of the process the draught in chimneys
which causes the combustion in proper furnaces does not amount to a depression of
more than twenty centimetres of water, that is to say, that by causing an average
depression of twenty centimetres of water in a reservoir communicating with the
hearth of a furnace, the combustion of the coal will be increased, and it will be easy
to make use of all the caloric evolved therefrom. A celebrated experimenter has
shewn, not only theoretically but also practically, that a great economy would be
effected in many circumstances by establishing artificial draughts. However, the
benefit accruing from such arrangements is in a great measure counterbalanced by
reason of the employment of apparatus for making a partial vacuum, and is not
considerable enough, for such arrangements to be applied to the ordinary fire-boxes
of steam-generators. It will be otherwise, as hereafter explained, when it is also
intended to extract the ammonia from the products of combustion.
In order to ensure the absorption of the ammonia, it is necessary that besides the
draught corresponding to a dépression of twenty centimetres of water, it may be
possible to have a pressure of at least fifty centimetres of water in order to force all
the products of the combustion through the liquid chemical products employed for
the extraction therefrom of the ammonia. It may be remarked that the ammonia
is more easily absorbed under pressure than under a vacuum as practised in gas-
works.
As 20cont+ 50 cont = 70 centimetres of water correspond to a mechanical power
of 1/15 of an atmosphere, if for losses and other causes a power corresponding to
thirty centimetres of water is added a mechanical power of 1/10 of an atmosphere
is obtained. 1/10 of an atmosphere corresponds to a power of a thousand kilo-
grammes for each cubic metre of products of combustion which are used. The
production of carbonic acid not increasing the initial volume of air, 1 kilo of coal
burnt will produce 10 cubic metres x 1000 kilos = 10,000 kilogrammetres.
A ton of coal will therefore require practically an expenditure of 10.000.000
kilogrammetres since the theoretical number is increased by more than 40%.
10.000.000 kilogrammetres divided by one horse power 270,000 km per hour
horse power working for one hour. If this power had to be produced by the steam
= 37

page_text: or a special generator heated by coal, two kilos of coal would be consumed
power which for 37 horse power would be 74 kilos and this at 20 f∞∞ = 1 fr 48
per horse
for obtaining, as already stated 5 kilogrammes of ammonia N H³ the actual value
of which is 2 fr 50 a kilo, that is to say a product having a value of 12 fr 50 to
3 cover a mechanical cost of 1 fr 48. It is obvious that this leaves a considerable
margin to cover all other expenses and allow an excess for net profit.
This expense of fuel need not even be incurred, since it is profitable to make use
of artificial draughts to better utilize the coal which is being consumed.
Supposing even that the result was nil in this case, there would be no reason for
using artificial draughts for ordinary industrial purposes, but in all cases it will
economize in these operations the 74 kilos of coal above mentioned. This will be
proved hereafter.
It is very rare, after the possible utilization of all the caloric contained in the
products of combustion, with the aid of a flue for the draught, that the lost
products do not carry away through the said flue at least 80 calories per cubic
metro of the original air which is most favourable, as in a flue 12 cubic metres or
more of air per kilo of coal burnt are often employed, instead of 10 cubic metres
which is computed for artificial draught.
As 1000 kilos of coal require 10,000 cubic metres of air, there is a loss of
10000 × 80 === 800.000 calories which represent about 110 kilos of coal, whereas
it has been stated that only a maximum of 74 kilos was required to obtain the
mechanical power necessary for effecting the complete absorption of the ammonia.
If all the preceding figures are applied to an industrial operation consisting in
absorbing and utilizing the ammonia proceeding from the combustion of 100 tons
of coal, the following results are obtained with reference to the mechanical part of
the process, that is to say with a special generator beated with coal.
7.400 of coal at 20 fr 00°/。。 costs 148 fr 00 per day and produces 500 k of
ammonia at 2 fr 50 per = 1250 fr. 00 per day This leaves for general expenses
and the chemical part of the process 1102 fr 00.
By using the lost heat the 1250 fr. per day remain disposable for general
expenses and the chemical part of the process hereafter to be described.
3700
24
It may be stated that the former heating gains thereby and pays the general
expenses of maintenance for the work of the special apparatus for the operation of
the gases. Now as to the power required to operate upon the products of the
combustion of 100 tons of coal burnt per day. As abovo stated, the power
necessary to operate upon the combustion gases of 1000 kilos of coal amount to
37 horse power per hour; for 100 tons, I obtain 37 x 100 = 3700 horse power
per hour or
= 155 horse power for 24 hours. If the original heating was not
altered, the cost of the mechanical part of the process with regard to the absorption
of ammonia would only be the maintenance, the hand labour and the amortization
required for an engine of 155 horse power in order to obtain a production of
1250 fr per day of ammonia, from which production must be deducted the cost of
the chemical part of the process. Thus, as regards the mechanical part of the
process the operation of extracting the ammonia from the products of the com-
bustion of coal would not cost anything, or at the most a very trifling amount.
Practically, the above operation is, in comparison with metallurgical operations,
much less expensive, as in the latter a single furnace consuming 100 tons per day, .
for instance, requires 500,000 cubic metres of air at a pressure which may rise to
20 centimetres of mercury, at an average cost of 3700 kilogrammetres including
osses. Now, 500,000 cubic metres × 3,700 =
270,000 Km machine power of 300 horse power going for 24 hours for a single
1,850,000.000 Km divided by
urnace, that is to say nearly half as much power as is required to extract the
ammonia from 100 tons of coal
=
Besides the mechanical and chemical parts of the process it is obvious that
ocalities and circumstances must be such that the application of these two parts.

page_text: may furnish the best economical results especially with regard to the mechanical
part of the process.
There are however much simpler means for collecting even on a large scale,
the ammonia proceeding from the coal. There are still a great number of coke
producers who not using the "Knab ovens loose the ammoniacal waters and the
tar in order to obtain a denser coke, the tar and the gas serving directly by their
combustion to produce the heat necessary for the conversion of coal into coke.
It is obvious that the volatilized matter from the coal contains all the ammonia,
or all the elements of the ammonia, that such coal may produce; and moreover all
the water entering in the composition of this coal is in the form of steam having a
high temperature, which, as it is being formed, produces in presence of the nitrogen
and carbonic acid of the air, sesquicarbonate and other salts of ammonia. From
calculations made, the volatile matter disengaged from coal in the manufacture of
coke corresponds to about 300 kilos of coal which could be burnt with the least
possible quantity of air, that is to say 9 cubic metres at the most. Therefore, it
is 2700 cubic metres of gaseous products, supposed cold, per ton of coal converted
into coke, and not 10,000 cubic metres, which have to be operated upon for the
absorption of the same quantity of ammonia. The power required will be reduced
in the proportion of 10,000 to 2,700 or from 155 horse power in 24 hours to
42 horse power for the treatment of 100 tons of coal, in order to obtain constantly
500 kilos of ammonia N H³ worth at the present current prices 2.50 per kilo
that is altogether 1250 fr. The mechanical power, especially in this case where
there is more heat recuperated, costs only engineer's wages, lubricating oil, and
amortization ete for an engine of 42 horse power which is a matter of no
importance.
Applied for extensive operations, the first problem, that is the mechanical part of
the process is thus entirely, practically and economically solved.
In consequence of the complete solution of this part of the process, the chemical
part thereof becomes now the most important. In extensive operations, the use of
hydrochloric acid for the absorption of ammonia is almost impossible on account of
its volatility as before being completely absorbed it would be partly carried away
by the considerable volume of the products of combustion. On the other hand,
sulphuric acid would entail a considerable expense for the total absorption of the
ammonia, as it would require for the absorption of 1 kilogramme of N H³, about
5 kilos of sulphuric acid from the chambers at 52° Baumé, an acid the transport of
which in bottles or carboys is difficult and costly. This acid would cost at least at
the place of manufacture 70 centimes per kilogramme of ammonia absorbed which
for 500 kilos would entail an expense of at least 350 francs per day.
Solid and low price substances like sulphate of lime which decompose carbonate
of ammonia are not applicable on account of the difficulty experienced in bringing
these solid substances into intimate contact with the gases of combustion.
There is however, a chemical substance more suitable than any other for
the absorption of carbonates or sesquicarbonates of ammonia, the production of
which has of late years become enormous. It is a residuum, heretofore useless
cumbersome, and valueless which may, if produced in large quantities, become
highly injurious in future times. This most cumbersome residuum is chloride of
calcium, Ca Cl₂..
When a gas containing a carbonate or sesquicarbonate of ammonia is passed
through a solution of this chloride, carbonate of lime is immediately precipitated
and the ammonia is fixed in the form of hydrochlorate of ammonia. This is a well
known reaction which is represented by the equation
(N H³)² (H 0)º (C Or)³ × (Cl Ca)³ = (Cl H N H³)² + (C O O, C O³)³ + COг.
At the present time in the manufacture of carbonate of soda from bicarbonate of
ammonia enormous quantities of chloride of calcium, are left as a residuum which
has to be disposed of at any price even at the risk of causing the pollution of

page_text: rivers, wells and the like. The following will explain the enormity of such
production.
There are companies converting 100,000 kilos of salt (Cl. Na) per day into
carbonate of soda when 733 kilos of utilized salt leaves at the end of the operation,
a residuum supposed to be, when dry, 693 kilos of chloride of calcium that is to
say for the 100 tons of salt above mentioned 94,000 kilos of anhydrous chloride, or
three or four times this amount when in solution.
Now, in order to entirely extract the ammonia (N H³) from the sesquicarbonate.
present in the products of combustion it requires for 100 kilos of ammonia
366 kilos of chloride of calcium supposed anhydrous. The 94,000 kilos above men-
tioned would then already suffice for the production per day of 28,000 kilos of
ammonia, in combination as a hydrochlorate, worth at the present time, at 2,50
per kilo of pure ammonia, 70,000 francs. By lowering the price per kilo to 2 fr 00,
it would still be worth 56,000 fres per day, When these results are obtained, it
will assist greatly the purposes of agriculture for which ammonia (as well as
phosphoric acid) is an absolute necessity, this ammonia being generally imported at
great expense into Europe, in the shape of guano, already becoming exhausted,
nitrates, and such like. It seems obvious, moreover, that there is no reason why
in a short period of time the above stated production may not be realized, which
only represents a treatment of 56,000 tons of coals per day in the conditions of yield
indicated, and even if it was requisite to double this 56,000 tons it would still be
practical as hereinafter explained.
Returning to the above moderate figure, reckoning for instance upon the con-
sumption of 100 tons of coals per day producing 500 kilos of ammonia supposed
pure; 100 kilos of ammonia will consume 366 kilos of anhydrous chloride, and
500 kilos of ammonia will consume 1830 kilos of anhydrous chloride or a solution
of chloride of calcium corresponding to the anhydrous chloride. Supposing that
this solution weighs three times as much as the anhydrous chloride, that is in
round numbers 1830 x 3 = 5,500 kilos, the raw material, being valueless, the only
cost will be its transport in large iron barrels at an average distance of 100 kilo-
inetres, for instance. An expense for transport of material and return of empties
of 5 fr. 00 per ton which expense for 5.500 = 27 fr 50, is a trifling one, in
comparison with the actual result of 500 kilos of ammonia worth 1250 francs.
What calls for particular attention, and what renders this method extremely
remarkable, is that the cost price of ammonia, as small as it may be, is entirely
independant of the yield in ammonia of coal. Suppose, for instance not a yield of
10 kilos per ton as some chemists admit, not even a yield of 5 % as admitted by
the communicators of this invention, but a yield of 21%, k of ammonia per ton of
coal, in order to produce the 500 kilos of ammonia; the weight of the coal being
doubled, the lost heat will be also doubled and consequently the daily mechanical
expense will remain the same.
The only difference is that instead of an engine of 42 horse power one of 84 horse
power would be required to be maintained.
With regard to the cost of chemicals it will always be the same, as only
5500 kilos of liquid chloride of calcium are required, costing at the factory
27 fr 50, for the production of 500 kilos of ammonia which is worth at present
prices 1250 francs.
The result of the reaction of gases upon the liquid chloride of calcium is, as
before stated, a mixture of carbonate of lime and hydrochlorate of ammonia, which
altogether forms a manure preferable to the pure salts of ammonia or nitrates
employed at the present time, as the mixture of soluble phosphate of lime and
sulphate of lime in hypophosphates prepared for agricultural purposes is preferable
to the pure soluble phosphate of lime. The result obtained from the above mixture
will be immediate as by heating it in a retort or boiler above 100° it will be directly
reconverted into sesquicarbonate easily convertible into bi-carbonate by known
processes. This process is employed in the production of sesqui-carbonate.

page_text: other expenses being covered by the coke manufactured. The apparatus and tho
arrangement which enables all the important results above mentioned to be
obtained will now be described.
The general arrangement of the apparatus is sufficiently indicated in Figure 1 of
the accompanying drawing.
A represents the extremity of the flue through which the products of com-
bustion pass from any furnace. These products are still at a temperature high
enough to necessitate their being cooled. They then pass through the pipe B into
a transverse pipe C from which extend a series of smaller tubes D, D, D
immersed in a receptacle full of water, which is renewed when required. A
transverse section of this receptacle is shewn in Figure 3. This sheet iron
receptacle E is supplied with cold water through a cock situated at the lower part
thereof at c. The heated water runs out at the upper part of the said receptacle
at i at the opposite end to which it entered. The small pipes D, D, D. convey the
gases to a long sheet metal receptacle F which serves as a sort of gasometer and
from which the exhaust pump draws these gases. A cock a permits the condensed
vapors to be withdrawn. A manometer m constantly indicates the pressure inside
the receptacle F which pressure can be regulated by increasing or decreasing the
speed of the exhaust pump.
Two parallel pipes G convey the gases to each extremity of the large cylinder H
of a blowing machine or fan and two parallel pipes I I serve for the egress of the
gases blown by the fan.
The large blowing and exhausting cylinder H is rotated in the ordinary manner
by a steam engine The parallel pipes II convey the gases to a long transverse
pipe J upon which are fixed several smaller pipes K as shown in Figure 2, theso
pipes K enter the ammonia collector L containing a chloride of calcium solution into
which portions of the said pipes dip equal to half the height of the liquid. In order
to ensure the complete collection or extraction of the ammonia from the sesqui-
carbonate especially when the liquid is nearly saturated, it is necessary to have at
least another vessel N which receives in the first instance a pure solution of chloride
of calcium,
When the solution in the vessel L is saturated it is drawn off and replaced by
that in the vessel N by means of the pipe T; a fresh solution being introduced in
the latter vessel the operation being repeated when required.
The gases proceed from the vessel N through the parallel tubes O into a vessel P
of sheet iron lined with lead and containing the sulphuric acid which is designed to
decompose the bydro-cyanate of ammonia and to retain the latter.
In extensive operations which should proceed with great regularity, it will be
advantageous to have two complete sets of collectors The gases deprived of all the
ammonia which they contained proceed through one or two large pipes Q into a
flue or chimney.
This process of treating waste gases may be used in connection with Knab's
coke ovens in which only tars and ammoniacal waters which are deposited
instantaneously are collected. The gas still contains, as before stated, 7 gr 1/2 of
ammonia per cubic meter and there would be no great outlay to obtain this double
result since the extractors are already at hand as well as the pipes and a large
gasometer serving as a reservoir. It must be understood that this method is
applicable to all coke ovens from the gaseous products of which the ammonia is not
extracted or only partially extracted. The same applies to all furnaces heated with
coal, wood or peat in which the ammonia of the products of combustion is also lost.
It will be seen that this invention is based upon a complete series of mechanical
and chemical operations which may individually have been applied, or are applied,
but under different conditions. Thus for instance blowing machines are universally
employed for metallurgical purposes but not for the same purposes for which they
are used according to this invention. At the present time unsuccessful attempts
are being made to use industrially and economically, gases of combustion for
extracting in a practical manner the ammonia therefrom or the lost gases from

page_text: coke ovens other than that of the "Knab" class, or the ammonia left in the gases
proceeding from such ovens. Chloride of calcium has however never been seriously
utilized under the conditions of this process. The proof of this is that chloride of
calcium is accumulating in dangerous proportions and that manufacturers of
carbonate of soda by means of bicarbonate of ammonia have thought of finding
means to get rid of it without polluting rivers, wells and the land surrounding their
factories. By means of this invention fresh results and products are obtained
which may rise to enormous value, by means which have not in any case been
applied under the same circumstances and which consequently have not produced
these considerable results.
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
First. A method or process for the economical production of ammonia, based
essentially upon the combination of a complete series of mechanical or chemical
"operations above described in detail and which permit the practical utilization of
an agent, in the production of ammonia from the gases of combustion from all
kinds of ovens, furnaces, and the like, which is entirely alkaline especially in the
state of sesquicarbonate or hydrocyanate or even of hydrocyanic acid; and as agents
for absorbing the ammonia, first the chloride of calcium, now valueless, which
converts the carbonate and sesquicarbonate of ammonia into hydro-chlorate of
ammonia and next the sulphuric acid which decomposes the hydrocyanic acid and
combines with the ammonia set free.
Second. The special arrangements of the apparatus shewn in the accompanying
drawing permitting_the_operation_to_be_carried-out-in-a-simple-and-practical
manner and which comprises a gas pump operating by exhaustion to create the
necessary draught for the combustion in the furnaces, and by blowing to cause the
cooled gases to pass into several series of mixers containing solutions of chloride of
'calcium and sulphuric acid and arranged in the manner above described.
Third. The application of the above apparatus to all kinds of ovens used for
industrial purposes, furnaces of steam boilers glass-furnaces, coke ovens of all
descriptions or metallurgical furnaces.
Dated this 3rd day of January 1885