IMPROVEMENTS IN THE METHOD OF AND APPARATUS FOR PROVISIONAL SPECIFICATION
Year: 1874

page_text: LETTERS PATENT to Samuel Henry Johnson, of Lea Bank Works,
Stratford, in the County of Essex, Manufacturing Chemist, for the
Invention of "IMPROVEMENTS IN THE METHOD OF AND APPARATUS FOR
PROVISIONAL SPECIFICATION left by the said Samuel Henry Johnson
at the Office of the Commissioners of Patents, with his Petition, on
the 2nd January 1874.
I, SAMUEL HENRY JOHNSON, of Lea Bank Works, Stratford, in the
County of Essex, Manufacturing Chemist, do hereby declare the nature
of the said Invention for "IMPROVEMENTS IN THE METHOD OF AND APPARATUS
POR SEPARATING FREE SULPHUR FROM SUBSTANCES WITH WHICH IT IS MIXED," to
be as follows:-
My Invention consists of certain improvements in the method of and
in apparatus used for separating sulphur by means of the chemical
agents herein-after mentioned from mixtures containing it in the free
state, such as sulphur ore or the material known as spent oxide of iron,
A

page_text: and of the method of manipulating the agent employed in such a
manner as to enable the desired result to be efficiently obtained without
any undue loss of the chemical agents during the process.
It will be found in practice that my improvements so facilitate the
manipulation as to enable the process to be carried out to commercial
advantage, an object which has not hitherto been successfully
attained.
I effect the separation in the manner which I will now describe. The
chemical agent which I find may be most beneficially employed is
bisulphide of carbon, and I proceed as follows:-I. take a suitable
quantity of the material to be operated upon, and where necessary it is
by any convenient means dried and brought to such a state of division
as is requisite for the complete solution of the sulphur which is mixed
with the material. I put it into a receptacle which herein-after is called
the extractor, provided with a filter of linen on cocoa fibre matting or
other suitable porous material on a perforated diaphragm near the
bottom. I then hermetically close the extractor.
.
In some cases where the material operated on is liable to adhere I use
an agitator, which works in the extractor and stirs up the material in the
manner herein-after mentioned. Through a pipe in the bottom of the
receptacle I then introduce as much bi-sulphide of carbon as is necessary.
to dissolve all the sulphur, taking care that an air cock on the top of the
extractor is open so as to permit the air to be expelled from the recep-
tacle. I next heat the contents of the extractor by means of a steam
jacket or liquid bath up to the boiling point of bi-sulphide of carbon,
keeping it in ebullition until the vapours arising therefrom shall have
expelled the atmospheric air, an operation which should be made as
carefully and completely as possible. When the bi-sulphide vapours
begin to be evolved at the air cock I close it and continue the appli-
cation of heat until a pressure of a few pounds to the square inch is
indicated. I then draw off the solution of sulphur by means of a cock
placed at the bottom of the extractor into an open cistern, in which a
few inches depth of water is always kept covering the solution in order
to prevent evaporation. A pipe from the cock then delivers the sulphur
solution beneath the level of the water. This cistern supplies a still.
provided with a condenser and suitable receiver, which I call the pure
spirit receiver. I next introduce into the extractor sufficient bi-sulphide.

page_text: of carbon to wash out the remainder of the sulphur solution, and repeat
the operation if necessary. These avashings may be run into another
receiver, which I call a washing receiver. In this case I use the
washings for the first treatment of the next batch operated upon in the
extractor, so it is only necessary to evaporate the strong solution. The
sulphur solution obtained by the first treatment with bi-sulphide of
carbon is then evaporated in the still, being heated by means of steam
in a jacket on the bottom of the still, until all or nearly all the
bi-sulphide of carbon is removed. The still is provided with blades or
scrapers, which are kept revolving close to the bottom during the latter
part of the distillation, so as to facilitate the evolution of the bi-sulphide
of carbon by preventing the sulphur from forming a mass at the
bottom still. At the close of the process of distillation I inject steam
directly into the still so as to expel the atmosphere of bi-sulphide of
carbon vapour and replace it with one of steam. I then open the still
and remove the sulphur. The condensed bi-sulphide of carbon is
available without deterioration for fresh operations..
In order to recover the bi-sulphide of carbon which remains in the
residue of the material operated on which is left in the extractor, I
inject steam at the top of the vessel so as to permeate the material and
evaporate the bi-sulphide of carbon. The vapours from the extractor
pass into the condenser of the still by means of a pipe and cock con-
nected therewith from the bottom of the extractor.
When the whole of the bi-sulphide of carbon has been evaporized and
displaced by the steam the extractor is opened and the residuum free
from sulphur removed.
In order the more clearly to understand the nature of this Invention
it is here necessary to explain that when bi-sulphide of carbon vapour is
mixed with atmospheric air the tension of the former is so considerable
at ordinary temperatures that one volume of air will impart the.
characteristics of a permanent incondensible gas to two volumes of
bi-sulphide of carbon vapour, consequently if air were allowed to mix*
during the process with bi-sulphide of carbon vapour the bi-sulphide of
carbon so mixed would be irrecoverably lost, and would be carried away
from the apparatus, and from the great density of the bi-sulphide of.
carbon vapour the loss would be considerable. Under these circum-.
stances it is expedient to permit as little air as possible to become mixed
with the bi-sulphide of carbon vapour in the apparatus, and to eliminate

page_text: therefrom as much as possible all the air spaces. It is with this object
that I introduce the bi-sulphide of carbon at the bottom of the extractor
in the manner above described, so as to float the air out of it through
the air cock without admixture with the bi-sulphide of carbon vapour,
and also displace the remainder of the air in the extractor by the vapour
of bi-sulphide of carbon produced by the application of heat to the
extractor as herein-before mentioned. The high specific gravity of the
bi-sulphide of carbon vapour permits of the expulsion of the air in an
effectual and complete manner without admixture, except a very trifling
amount at the close of the operation, and with the same object. I also
permit the temperature of the bi-sulphide of carbon in the extractor to
be raised beyond the boiling point so as to drive out the solution of
sulphur without permitting air to enter the apparatus.
It is also
apparent that the subsequent washing above referred to may be effected
without the necessity of opening the air cock, for the bi-sulphide of
carbon vapour will condense on cooling, thus producing a partial vacuum
by means of which the quantity of bi-sulphide of carbon sufficient for
the purpose is introduced. With the same object any incondensible
vapours passing through the condenser are conducted by means of
a pipe into an ordinary gas holder, free communication with which
is permitted to obtain through the condenser during the distillation
of the sulphur solution, but it is closed at the termination before
opening the still to remove the sulphur.
At the commencement of each fresh operation of distillation of the
sulphur solution after the first operation has been completed and before
charging the still from the supply cistern the incondensible mixture of
bi-sulphide of carbon vapour and atmospheric air is permitted to flow
from the gas holder by means of a pipe passing nearly to the bottom of
the still in quantity sufficient to float out all the atmospheric air and
replace it with air saturated with bi-sulphide of carbon, the great density
of the mixture permitting this to be done with facility. When the dis-
tillation has commenced this saturated air finds its way back again into
the gas holder ready for another operation, or the air in the still may be
displaced by steam, which on condensing would permit the entry of the
bi-sulphide of carbon solution to be evaporated, and thus dispense with
the use of a gas holder for this purpose, but the employment of a gas
holder is better because it prevents the entry of air during the process of
distillation

page_text: In order to raise the bi-sulphide of carbon from the receivers to the
extractor I close the receivers hermetically and maintain them always
quite filled with water (which also eliminates the air spaces). Small
overflow cocks at their tops permit the water to flow out in proportion as
it is displaced by the bi-sulphide of carbon; pipes for the passage of the
bi-sulphide of carbon from the receivers to the extractors pass water-tight
through the tops of the receivers to nearly their bottoms; and the
external ends of the pipes are connected with the extractor.
The flow of the bi-sulphide of carbon through the pipes is controlled by
means of cocks. Water can be admitted at the top of the receivers by
means of cocks or valves attached to a water pipe, conveying the water
under sufficient pressure to force the bi-sulphide of carbon from the
bottom of the receivers up the pipes into the extractor, the water acting
as a liquid piston. I thus force the bi-sulphide of carbon to a higher
level without any mechanical appliances, such as pumps, &c., in direct
contact with the bi-sulphide of carbon, and so avoid loss by leakage and a
complicity of joints which is most desirable in working with bi-sulphide
of carbon. When spent oxide of iron is the substance under treatment,
I find it necessary to use an agitator in the receptacle, for although the
process of lixiviation in beds by percolation can be effected on the small
scale in the laboratory, yet on the large scale I find such an operation to
be impracticable owing to the material being liable to cohere or become
consolidated into a block impervious to the bi-sulphide of carbon, the
particles being cemented together by the sulphur.
I employ an agitator consisting of arms or blades turning on an axis
and made to work in the receptacle by any convenient means, I intro-
duce into the receptacle a quantity of bi-sulphide of carbon equal to
twice the weight of the oxide under treatment, taking care that such
introduction of the bi-sulphide of carbon does not occupy more than a
few minutes, which by the system of raising the bi-sulphide of carbon
herein described is readily effected, care baving been taken to have the
pipes from the receiver sufficiently large. Having displaced the air as
herein-before described and closed the air cock at the top of the
extractor, I then agitate the contents so as quickly to effect the com-
plete solution of the sulphur, which effected there is then no tendency
in the material to become consolidated.
Another modification is sometimes required to remove the solution of
sulphur from the residuum of the spent oxide, when the material

page_text: operated on consists to any considerable extent of fine particles, because
on then attempting to filter off the solution of sulphur the pores of the
filter soon become filled with the finer particles and the process becomes
ineffectual.
Numerous experiments have been tried with different textile fabrics
as a filtering medium, but without any advantage, as the pores in all
became speedily choked.
I will now explain a method of working and forming a filter which I
have found to answer the purpose in a very effectual manner. The
principles upon which it is founded are the following:
:-
Firstly. When bodies of different sizes but of the same or nearly the
same specific gravity are permitted to sink in a fluid of lesser gravity,
the larger masses sink faster than the smaller, because they present less
surface to the resistance of the fluid in proportion to their weight, and
therefore the bodies will arrange themselves in the order of their
respective sizes, the larger being at the bottom.
Secondly. It is well known that such an arrangement of solid matter
is the best for the formation of a filter bed. Now in order to form such
a filter bed in the extractor, I so agitate the contents thereof that the.
whole of the solid matter may be brought into a state of suspension in
the fluid. I then suddenly stop the agitation and permit the solid
matter to subside for about 30 minutes. Under these circumstances the
residuum in the extractor which usually consists of particles from the
size of a pea, or larger, to that of a fine impalpable powder arranges itself
in the best condition for filtration. On then opening the cock under the
filtering bottom, the solution of sulphur filters off without any difficulty,
and very quickly. The filter should also be similarly formed from the
residuum insoluble in the bi-sulphide of carbon before forcing out the
subsequent washings. By this treatment after the washings have been
removed the evaporation of the bi-sulphde of carbon from the residuum
by the direct, injection of steam at the top of the extractor is rendered
practicable, which has not been the case hitherto. The reason of this

page_text: And, Secondly. Because at the termination of the process of filtration
a considerable portion of the liquid (which would be retained' in the
interspaces between the particles of the residuum by capillary attraction
if the liquid had been allowed to run away by gravitation solely) is
forced out by the expansion of the bi-sulphide of carbon vapour. which
under tension had been the means of effecting the filtration, as already
described. With these modifications the separation of the sulphur from
spent oxide of iron is quickly and completely effected.
In case the spent oxide of iron should contain too little of the coarser
particles I find it advisable to mix it with spent oxide. containing,a
greater proportion, or with some inactive material of such a specific
gravity, size, and shape as will confer the necessity porosity, but generally
the material requires no such admixture.
These improvements applicable to the treatment of spent oxide are
also of value in treating substances such as some descriptions of sulphur
ore which on being crushed for the purpose of separating the sulphur by
the process produce much finely divided mineral matter, and should be
adopted when the process of filtration is difficult.
Although I have described my improvements with reference to the
use of bi-sulphide of carbon, which is the agent that I find may be most
beneficially used, other chemical agents may be employed. For instance,
I may use light hydrocarbons obtained by fractional distillation of coal
tar or petroleum (which should be capable of complete volatilization at a
temperature below 212 degrees Fahrenheit), but in this case it will be
necessary when the light hydrocarbons or other chemical agent lighter
than water are employed to modify the method and apparatus in a
manner that will be obvious to a person of experience and skill in
operations of the character above referred to. For instance, it will be
apparent that owing to the specific gravity of the hydrocarbons or other
like agent being less than that of water that they will float on the water,
and in consequence it will be necessary to alter the arrangement of the
pipes communicating with the receivers so that the water may be
introduced at the bottom for the purpose of forcing out the hydrocarbons
or other like agent at the top of the receivers.
The overflow cock at the level of the top of the receiver should be
connected by means of a pipe with the bottom thereof in such a manner
as to cause the water to be displaced by the superimposed pressure of

page_text: the column of hydrocarbons or other like agent, which column should
be sufficiently prolonged above the level of the top of the receivers to
afford sufficient pressure for the purpose. And further, it will be
apparent that the cistern which receives the sulphur solution from the
extractor to supply the still must be hermetically closed on the top and
maintained full of water in a similar manner to that which I have last
described with respect to the receivers. Or in lieu thereof may be
substituted any of the ordinary gas holders which are used for the
purpose of collecting gases over water as it can be collected and trans-
ferred in manner similar to any ordinary gas, provided the solution of
sulphur is of less specific gravity than water. It is obvious that the
agent employed should be one that is not soluble in water.
When I use light hydrocarbons as solvents for the sulphur the process
of distillation may be dispensed with, the sulphur being separated there-
from by crystallization from the solution on cooling. The hydrocarbons
adherent to the deposited sulphur should be separated by heat in closed
apparatus so arranged as to avoid the loss of the solvent and so as to
facilitate the manipulation of the same by methods which from the
description of the manipulation of the bi-sulphide of carbon herein-before
contained will be obvious to persons experienced in operations of this 2
nature.
Some such light hydrocarbons obtained by fractional distillation, as
herein-before described, possess the property of dissolving a considerable
proportion of sulphur at their boiling points and of retaining but little
sulphur in solution on cooling, and it is with such hydrocarbons that I 2
recommend the adoption of the system of refrigeration instead of
distillation herein-before last referred to.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Samuel Henry Johnson, in the Great Seal Patent
Office on the 2nd July 1874.

page_text: WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Second day of January, in the year of our
Lord One thousand eight hundred and seventy-four, in the thirty-
seventh year of Her reign, did, for Herself, Her heirs and successors,
give and grant unto me, the said Samuel Henry Johnson, Her special
license that I, the said Samuel Henry Johnson, my executors, adminis-
trators, and assigns, or such others as I, the said Samuel Henry
Johnson, my executors, administrators, and assigns, should at any time
agree with, and no others, from time to time and at all times there-
after 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 METHOD OF AND APPARATUS FOR SEPARATING FREE
SULPHUR FROM SUBSTANCES WITH WHICH IT IS MIXED," upon the condition
(amongst others) that I, the said Samuel Henry Johnson, 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 Samuel Henry Johnson, do
hereby declare the nature of the said Invention, and in what manner
the same is to be performed, to be particularly described and ascertained
in and by the following statement thereof, that is to say :—
My Invention consists of certain improvements in the method of and
in apparatus used for separating sulphur by means of the chemical
agents herein-after mentioned from mixtures containing it in the free
state, such as sulphur ore or the material known as spent oxide of
iron, and of the method of manipulating the agent employed in such a
manner as to enable the desired result to be efficiently obtained without
any undue loss of the chemical agents during the process.
It will be found in practice that my improvements so facilitate the
manipulation as to enable the process to be carried out to commercial
advantage, an object which has not hitherto been successfully
obtained.
I effect the separation in the manner which I will now describe :—The

page_text: chemical agent which I find may be most beneficially employed is bi-
sulphide of carbon, and I proceed as follows:-I take a suitable
quantity of the material to be operated upon by any convenient means;
and as this should be thoroughly dry it is where necessary dried, and is
brought to such a state of division as is requisite for the complete
solution of the sulphur, which is mixed with the material. I put it
into a receptacle, which herein-after is called the extractor, provided
with a filter of linen on cocoa fibre matting or other suitable porous
material, on a perforated diaphragm or grating near the bottom; I then
hermetically close the extractor.
In the extractor I use an agitator, which stirs up the material
in the manner herein-after mentioned. Through a pipe in the bottom
of the receptacle I then introduce as much bi-sulphide of carbon
as is necessary to dissolve all the sulphur, taking care that an air
cock on the top of the extractor is open, so as to permit the air to be
expelled from the receptacle. I next heat the contents of the extractor
by means of a steam jacket or liquid bath up to the boiling point of
bi-sulphide of carbon, keeping it in ebullition until the vapours arising
therefrom shall have expelled the atmospheric air, an operation which
should be made as carefully and completely as possible. When the bi-
sulphide vapours begin to be evolved at the air cock I close it, and con-
tinue the application of heat until a pressure of a few pounds to the
square inch is indicated. I then draw off the solution of sulphur by
means of a cock placed at the bottom of the extractor into an open
cistern, in which a few inches' depth of water is always kept covering
the solution, in order to prevent evaporation. A pipe from the cock
then delivers the sulphur solution beneath the level of the water. This
cistern supplies a still provided with a condenser and suitable receiver,
which I call the pure spirit receiver. I next introduce into the extractor
sufficient bi-sulphide of carbon to wash out the remainder of the sulphur
solution, and repeat the operation if necessary. These washings are run
into another receiver, which I call a washings receiver. In this case I
use the washings for the first treatment of the next batch operated upon
in the extractor, so that it is only necessary to evaporate the strong
solution. The sulphur solution obtained by the first treatment with bi-
sulphide of carbon is then evaporated in the still, being heated by means
of steam in a jacket on the bottom of the still until all or nearly all the
bi-sulphide of carbon is removed. The still is provided with blades or

page_text: scrapers, which are kept revolving close to the bottom during the latter
part of the distillation, so as to facilitate the evolution of the bi-sulphide
of carbon by preventing the sulphur from forming a mass at the bottom
of the still. At the close of the process of distillation I inject steam
directly into the still, so as to expel the bi-sulphide of carbon vapour,
and replace it with one of steam. I then open the still and remove the
sulphur. The condensed bi-sulphide of carbon is available without
deterioration for fresh operations.
In order to recover the bi-sulphide of carbon which remains in the
residue of the material operated on, which is left in the extractor I
inject steam at the top of the vessel so as to permeate the material, and
.displace and evaporate the bi-sulphide of carbon. The resulting vapours
pass from the extractor into the condenser of the still by means of a
pipe and cock connected therewith from the bottom of the extractor.
When the whole of the bi-sulphide of carbon has been vaporized, and
displaced by the steam, the extractor is opened and the residuum free
from sulphur removed.
In order the more clearly to understand the nature of this Invention
it is here necessary to explain that when bi-sulphide of carbon vapour is
mixed with atmospheric air the tension of the former is so considerable
at ordinary temperatures that one volume of air will impart the charac-
teristics of a permanent incondensible gas to two volumes of bi-sulphide
of carbon vapour, consequently if air were allowed to mix during the
process with bi-sulphide of carbon vapour the bi-sulphide of carbon so
mixed would be irrecoverably lost, and would be carried away from the
apparatus; and from the great density of the bi-sulphide of carbon
vapour the loss would be considerable. Under these circumstances it is
expedient to permit as little air as possible to become mixed with the
bi-sulphide of carbon vapour in the apparatus, and to eliminate there-
from as much as possible all the air spaces. It is with this object that
I introduce the bi-sulphide of carbon at the bottom of the extractor in
the manner above described, so as to float the air out of it through the
air cock without admixture with the bi-sulphide of carbon vapour, and
also displace the remainder of the air in the extractor by the vapour of
the bi-sulphide of carbon produced by the application of heat to the
extractor, as herein-before mentioned. The high specific gravity of the
bi-sulphide of carbon vapour permits of the expulsion of the air in an

page_text: effectual and complete manner without admixture, excepting a very
trifling amount at the close of the operation; and with the same object
I also permit the temperature of the bi-sulphide of carbon in the
extractor to be raised beyond the boiling point, so as to drive out the
solution of sulphur without permitting air to enter the apparatus. It is
also apparent that the subsequent washing above referred to may be
effected without the necessity of opening the air cock, for the bi-sulphide
of carbon vapour will condense on cooling, thus producing a partial
vacuum by means of which the quantity of bi-sulphide of carbon
sufficient for the purpose is introduced. With the same object any
incondensible vapours passing through the condenser are conducted by
means of a pipe into an ordinary gas holder, free communication with
which is permitted to obtain through the condenser during the distil-
lation of the sulphur solution, but it is closed at the termination before
opening the still to remove the sulphur.
At the commencement of each fresh operation of distillation of the
sulphur solution after the first operation has been completed, and before
charging the still from the supply cistern, the incondensible mixture of
bi-sulphide of carbon vapour and atmospheric air is permitted to flow
from the gas holder by means of a pipe passing nearly to the bottom of
the still in quantity sufficient to float out all the atmospheric air and
replace it with air saturated with bisulphide of carbon, the great density
of the mixture permitting this to be done with facility. When the
distillation has commenced this saturated air finds its way back again
into the gas holder ready for another operation; or the air in the still
may be displaced by steam, which on condensing would permit the entry
of the bi-sulphide of carbon solution to be evaporated, and thus dispense
with the use of a gas holder for this purpose, but the employment of a
gas holder is better because it prevents the entry of air during the
process of distillation.
In order to raise the bi-sulphide of carbon from the receivers to the
extractor I close the receivers hermetically and maintain them always
quite filled with water (which also eliminates the air spaces). Small
overflow cocks at their tops permit the water to flow out in proportion
as it is displaced by the bi-sulphide of carbon. Pipes for the passage of
the bi-sulphide of carbon from the receivers to the extractors pass water-
tight through through the tops of the receivers to nearly their bottoms,
and the external ends of the pipes are connected with the extractor.
j

page_text: The flow of the bi-sulphide of carbon through the pipes is controlled
by means of cocks. Water can be admitted at the top of the receivers
by means of cocks or valves attached to a water pipe conveying the
water under sufficient pressure to force the bi-sulphide of carbon from
the bottom of the receivers up the pipes into the extractor, the water
acting as a liquid piston. I thus force the bi-sulphide of carbon to a
higher level without any mechanical appliances, such as pumps, &c., in
direct contact with the bi-sulphide of carbon, and so avoid loss by
leakage and a complicity of joints (which is most desirable in working
with bisulphide of carbon). When spent oxide of iron is the substance
under treatment I find it necessary to use an agitator in the receptacle,
for although the process of lixiviation in beds by percolation can be
effected on the small scale in the laboratory, yet on the large scale I find
such an operation to be impracticable owing to the material being liable
to cohere or become consolidated into a block impervious to the bi-
sulphide of carbon, the particles being cemented together by the
sulphur.
I employ an agitator consisting of arms or blades turning on an axis,
and made to work in the receptacle by any convenient means. I intro-
duce into the receptacle a quantity of bi-sulphide of carbon equal to
twice the weight of the oxide under treatment, taking care that such
introduction of the bi-sulphide of carbon does not occupy more than a
few minutes, which by the system of raising the bi-sulphide of carbon
herein described is readily effected, care having been taken to have the
pipes from the receiver sufficiently large. Having displaced the air, as
herein-before described, and closed the air cock at the top of the
extractor, I then agitate the contents so as quickly to effect the
complete solution of the sulphur, which effected there is then no ten-
dency in the material to become consolidated.
Another modification is sometimes required to remove the solution of
sulphur from the residuum of the spent oxide when the material operated.
on consists to any considerable extent of fine particles, because on then
attempting to filter off the solution of sulphur the pores of the filter
soon become filled with the finer particles, and the process becomes
ineffectual. Numerous experiments have been tried with different
textile fabrics as a filtering medium, but without any advantage, as the
pores in all become speedily choked.

page_text: I will now explain a method of working and forming a filter which I
have found to answer the purpose in a very effectual manner.. The
principles upon which it is founded are the following:-
Firstly. When bodies of different sizes, but of the same or nearly the
same specific gravity are permitted to sink in a fluid of lesser gravity
the larger masses sink faster than the smaller because they present less
surface to the resistance of the fluid in proportion to their weight, and
therefore the bodies will arrange themselves in the order of their respec-
tive sizes, the larger being at the bottom.
Secondly. It is well known that such an arrangement of solid matter
is the best for the formation of a filter bed. Now in order to form such
a filter bed in the extractor I so agitate the contents thereof that the
whole of the solid matter may be brought into a state of suspension in
the fluid. I then suddenly stop the agitation and permit the solid
matter to subside for about 30 minutes. Under these circumstances the
residuum in the extractor (which usually consists of particles from the
size of a pea or larger to that of a fine impalpable powder) arranges
itself in the best condition for filtration. On then opening the cock
under the filtering bottom the solution of sulphur filters off without any
difficulty, and very quickly. The filter should also be similarly formed
from the residuum insoluble in the bi-sulphide of carbon before forcing
out the subsequent washings.. By this treatment, after the washings
have been removed, the evaporation of the bi-sulphide of carbon from
the residuum by the direct injection of steam at the top of the extractor
is rendered practicable, which has not been the case hitherto. The
reason of this is,―
Firstly. Because the material so deposited from a state of suspension
in the fluid is in the most porous possible arrangement, which therefore
admits of the free passage of the steam through the material.
And, Secondly. Because at the termination of the process of filtration
a considerable portion of the liquid (which would be retained in the
interspaces between the particles of the residuum by capillary attraction
if the liquid had been allowed to run away by gravitation solely) is
forced out by the expansion of the bi-sulphide of carbon vapour, which
under tension had been the means of effecting the filtration as already
described. With these modifications the separation of the sulphur from
spent oxide of iron is quickly and completely effected.

page_text: In case the spent oxide of iron should contain too little of the coarser
particles, I find it advisable to mix it with spent oxide containing a
greater proportion, or with some inactive material of such a specific
gravity, size, and shape as will confer the necessary porosity, but
generally the material requires no such admixture.
These improvements applicable to the treatment of spent oxide are
also of value in treating substances such as some descriptions of sulphur
ore, which on being crushed for the purpose of separating the sulphur
by the process produce much finely divided mineral matter, and should
be adopted when the process of filtration is difficult. -
Although I have described my improvements with reference to the
use of bi-sulphide of carbon, which is the agent that I find may be most.
beneficially used, other chemical agents may be employed. For instance,
I may use light hydrocarbons obtained by fractional distillation of coal
tar or petroleum (which should be capable of complete volatilization at a
temperature below 212 degrees Fahrenheit), but in this case it will be
necessary, when the light hydrocarbons or other chemical agents lighter
than water are employed, to modify the method and apparatus in a
manner that will be obvious to a person of experience and skill in
operations of the character above referred to. For instance, it will be
apparent that owing to the specific gravity of the hydrocarbons or other
like agent being less than that of water that they will float on the water,,
and in consequence it will be necessary to alter the arrangement of the,
pipes communicating with the receivers, so that the water may be
introduced at the bottom for the purpose of forcing out the hydrocarbons
or other like agent at the top of the receivers.
The overflow cock at the level of the top of the receiver should be
connected by means of a pipe with the bottom thereof, in such a manner.
as to cause the water to be displaced by the superimposed pressure of
the column of hydrocarbons or other like agent, which column should be
sufficiently prolonged above the level of the top of the receivers to afford'
sufficient pressure for the purpose. And further it will be apparent that
the cistern which receives the sulphur solution from the extractor to:
supply the still must be hermetically closed on the top and maintained.
full of water, in a similar manner to that which I have last described
with respect to the receivers. Or in lieu thereof may be substituted any
of the ordinary gas holders which are used for the purpose of collecting

page_text: gases over water, as it can be collected and transferred in manner similar
to any ordinary gas provided the solution of sulphur is of less specific
gravity than water. It is obvious that the agent employed should be one
that is not soluble in water.
When I use light hydrocarbons as solvents for the sulphur the process
of distillation may be dispensed with, the sulphur being separated there-
from by crystallization from the solution on cooling. The hydrocarbons
adherent to the deposited sulphur should be separated by heat in closed
apparatus so arranged as to avoid the loss of the solvent, and so as to
facilitate the manipulation of the same by methods which, from the
description of the manipulation of the bi-sulphide of carbon herein-before
contained, will be obvious to persons experienced in operations of this
nature..
Some such light hydrocarbons obtained by fractional distillation as
herein before described possess the property of dissolving a considerable
proportion of sulphur at their boiling points, and of retaining but little
sulphur in solution on cooling, and it is with such hydrocarbons that I
recommend the adoption of the system of refrigeration instead of dis-
tillation herein-before last referred to.
In order that my said Invention may be most fully understood and
readily carried into effect, I will proceed to describe the Drawings here-
unto annexed, which shew apparatus designed more particularly for the
treatment of spent oxide by means of bi-sulphide of carbon.
Figure 1 is an elevation partly in section of the apparatus, omitting
the condensers and gasometer, which parts are shewn separately in
elevation, partly in section, at Figure 2.
Figure 3 is a plan, also partly in section, of the apparatus, omitting
the stills, which are shewn separately in plan at Figure 4.
a, a, are a pair of extractors. They are cylinders of a convenient size,
say eight feet in diameter, so constructed as to be safe up to a moderate
pressure, say twenty pounds to the inch (although so high a pressure is
never required), and they should also be able to resist the atmospheric
pressure when there is a vacuum within. There is a man-hole at a¹ in
the top of of the cylinder, and another at a² in the bottom. These man-

page_text: The lower part of the side of the extractor is steam jacketted at a³,
and the jacket has a safety valve upon it at a*. a³ is a wooden grating
at the bottom of the extractor; it has an opening in it at a³× corre-
sponding with the bottom man-hole. Over the grating a³ a coarse linen
cloth a is laid; it has a gasket sewn around its edge, and this is slightly
caulked into the crevice between the edge of the grating and the side of
the extractor. The cloth does not cover the man-holc, and here it is also
made to fit close by means of a gasket. a' is a vertical axis within the
extractor, and passing out through a stuffing box at the top. This
stuffing box I pack with cotton, and I lubricate it with soft soap. Upon
the axis a' are curved arms a³, which when the axis revolves pass over
and close to the surface of the filter cloth, stirring up the material resting
upon it. a is a beveled wheel fixed on the top of the axis a', and a¹⁰ is
a pinion gearing with it, the axis of which pinion is driven by the steam
engine a". The exhaust steam of the engine is passed into the steam
jackets, and aids in heating the vessels.
a12 is a mercural pressure
gauge inserted into the top of the extractor, and capable of shewing the
pressure up to, say, thirty inches of mercury.
The spent oxide having been first thoroughly dried and powdered; for
any moisture interferes seriously with the action of the solvent, is placed.
in the extractor so as to rest upon the filter cloth. The man-hole is then
closed down air-tight, and bi-sulphide of carbon is drawn from a reservoir
herein-after described into the extractor through the pipe b. I prefer
to use 20 gallons of bi-sulphide for each hundredweight of the charge
of dry material, and the two together should about three-quarters fill the
extractor. The steam is then admitted into the jacket, and the engine
is set slowly to work, turning the agitator and mixing the charge, the
air pipe c being at this time left open, vapour is soon produced, and
being much denser than air, and the heat being carefully applied, it
mixes with it but slightly, and by far the greater part of the air is
displaced and escapes by the air pipe c before the bi-sulphide vapour
B

page_text: commences to come over. As soon as this vapour issues at the mouth
of the air pipe the pipe is closed by the cock upon it.
If it be thought worth while a small condensing worm may be fitted
at the end of the air pipe, to prevent for the most part the trifling loss of
bi-sulphide vapour which otherwise takes place. After the air cock has
been closed the heat is continued until a pressure of from 5 to 10 inches
of mercury is attained, and the speed of the agitator is increased until it
is sufficient to keep the whole or nearly the whole of the solid matter
suspended in the solvent. At this time, say, about one quarter of an
hour from the commencement of the operation of agitation the agitator
is stopped, and the pressure is not further increased. The solid material
then deposits and forms a graduated filter bed, coarse at the bottom, and
becoming finer and finer in successive layers upwards. This will bo
sufficiently accomplished in about thirty minutes, and then the cock d'
on the pipe d is opened, and the solution of sulphur is forced out by the
pressure of the vapour through the filter into the receiver e herein-after
described. This having been accomplished, a further quantity of bi-
sulphide of carbon equal to one-half of that first employed is admitted
into the extractor as the vapour therein condenses, and without opening
the air cock. The operation is now repeated, except that the washings
are not drawn into the sulphur solution receiver e, but the spirit is made
to return by the same pipe 6 by which it entered, and is passed into a
separate vessel herein-after described provided for the purpose. Steam
is next admitted at the top of the extractor by the pipe f, for the purpose
of vaporising the remaining solvent and forcing out the vapour by the
pipe g, which leads to a condenser herein-after described. This having
been done the extractor is opened, a truck h is run under the bottom
man-hole, and the agitator being set to work the spent material is
rapidly discharged and conveyed away. The filter cloth which is now
moist is removed; it is replaced with a dry one, and then all is ready for
working another charge.
The receiver for sulphur solution e is an iron tank open at the top; it
contains the solution and a few inches of water standing upon its surface
to prevent evaporation. The pipe d by which the solution is admitted
passes down a larger pipe e¹ nearly to the bottom of the tank. This is to
prevent any air bubbles entering with the liquid rising through the
water in the tank, as such air would carry up with it globules of solvent,
and so a sensible loss would result. The solution stands in the pipe e¹

page_text: with water over it. Any globules of bi-sulphide carried up by the air
through the water being confined within a narrow space coalesce and
then sink again; there is consequently but very slight loss by evaporation.
at the surface; e², e², are indicating floats, shewing the amount of
sulphur solution in the tank; e³ is the cock by which the sulphur
solution is drawn off into the stills to be distilled; i, i, are the stills;
they are closed cylinders similar to the extractors, with man-holes at
the bottom. They have double bottoms, and steam is admitted between
the two by the pipe k, which also serves to supply steam to the jackets
of the extractors, and to the steam engines which work the stirrers in
these vessels, and also in the stills.
The stirrer in each still consists of a vertical axes with arms 2, 2²,
upon it. One of the arms is inclined to plough up the sulphur and
prevent it forming a cake at the bottom of the still, and is so set as to
keep the bottom quite free from deposit. The other is curved so as to
act more efficiently to discharge the sulphur at the end of the operation,
when the man-hole at the bottom is open.
The axes of the stirrers in the stills are carried and driven in the same
way as those in the extractors, and is the steam engine by which they
are actuated; it exhausts into the spaces at the bottoms of the stills.
are safety valves on these steam spaces; are pipes by which the
condensed water is drawn off.
The distilling operation is conducted in the following manner :-
The still having been closed at the end of the last operation of dis-
tillation the air is expelled from it through the air pipe which is left
open at the end; this is done by admitting an incondensible mixture of
bi-sulphide vapour and air which is kept stored in a gas holder 1, and
the gaseous mixture is led into the still by the pipe 7, and it is caused
to flow gently by removing some of the counterpoise weights 1 of the
gas holder. As soon as the air is expelled the air cock is closed and the
counterpoised weights are restored, the still is then about one half filled
with sulphur solution by opening the cock e³; the heat is then applied
and the pipe leading from the still head to the condenser m is opened.
The evaporation is carried on with care to avoid priming into the con-
denser by the aid of the mercury gauge and observation through the
sight hole which is glazed with talc.
When the sulphur begins to be deposited the agitator is turned slowly
to keep the deposited sulphur in a granular state, and especially towards

page_text: the end of the operation it is kept constantly at work, and its speed is then
increased to prevent the formation of a non-conducting cake upon the
still bottom. When the process is complete and bi-sulphide vapour is no
longer generated steam is blown into the still by opening a cock on the
branch of the steam pipe so as effectually to separate the remaining
solvent from the sulphur, and to sweep forward the vapour in the still
into the condenser. The connection with the condenser is then closed
and the still is opened, a truck is run beneath it, and the agitator being
again set to work the sulphur is rapidly discharged into the truck.
The condenser m into which at the upper end the bi-sulphide vapour
passes is constructed like a tubular boiler; there is a vapour space at
each end, and these are connected by a number of small iron tubes
which are surrounded with cold water admitted by the water pipe n and
draw off into a drain by the pipe o.
The condensed bi-sulphide runs
out at the bottom of the condenser by the pipe m¹ which branches into ]
two pipes m² and m³. The pipe m² leads into the pure spirit receiver p
herein-after described, whilst the pipe m³ passes to the top of a second
condenser q consisting of a rectangular coil q² of iron pipes of large
diameter contained in a water cistern q³, and a stream of cold water is
admitted constantly at the bottom of this cistern by a pipe q³ and drawn a
off at the top by an overflow q* which leads into a drain.
The condensed bi-sulphide together with the incondensible mixture of
vapour and air is led away from the bottom of this condenser by the
pipe q' by a branch q°; from this pipe the gaseous mixture enters the gas
holder, whilst the liquid flows into the pure spirit receiver p. The a
pure spirit receiver p and the washings receiver are two similar
cylindrical vessels closed at the top and provided with man-holes. The
bi-sulphide is admitted to them and drawn off from them by the pipes p¹
and, which both connect with the rising pipe 6 leading to the
extractors.
The spirit is, when required, forced up into the extractors by admitting
water under pressure at the top of the receiver by one or other of the
pipes p³, 3, and when it is desired that spirit should descend from the
extractors into the washings receiver it is permitted to do so by opening
the cocks upon the spirit pipe 6 and also the cock ³, which allows water 3
to flow out from the top of the washings receiver into the drain. In a
similar way when the pure spirit receiver is receiving spirit from the

page_text: condenser water is allowed to escape at the top of the receiver by the
cock p³.
The gas holder is clearly shewn in the Drawings, and as it is of ordinary
construction no further description of it is required. The bi-sulphide
gas, as it may be called, enters by the pipe q* and is drawn off for use by
the pipe .
Although I prefer to employ bi-sulphide of carbon as the solvent,
nevertheless light hydrocarbon oil may be employed; these oils being
lighter than water some obvious modifications of the apparatus will be
required; and further, for treatment with hydrocarbons of light gravity,
as described, in such cases whereon cooling a considerable deposition of
sulphur would take place it is necessary to avoid the radiation of heat
from the eduction cock and pipe from the extractor by covering them
externally with a suitable non-conducting material, or by jacketting
them so as to afford the facility of keeping them warm where required
by means of steam or liquid bath; and in such cases it is further
necessary either to run the solution of sulphur from the extractor directly
into the still, or else to provide some means of maintaining the sulphur
solution in the supply cistern at a temperature above that at which the
sulphur would be deposited.
Having thus described the nature of my said Invention, and the
'manner of performing the same, I would here remark that I do not
claim the separation of sulphur by employing the bi-sulphide of carbon
as a solvent in a closed apparatus arranged for the purpose, and separating
the products by distillation which has frequently been proposed but not
hitherto successfully worked, but what I claim is,―
1st. The methods of eliminating the air so as to avoid the loss of
bi-sulphide of carbon or other solvent employed, as and for the purpose
herein described.
2nd. The treatment as herein described of the materials in the
extractor with bi-sulphide of carbon or other solvent at a temperature
above its boiling point so as to increase its solvent action in the process,
and to facilitate the removal of the sulphur solution without admitting
air to the apparatus.
3rd. The method of treating the materials in the extractor by bringing
the solid matter into a state of suspension in the liquid, firstly, to effect

page_text: complete solution of the sulphur; and, secondly, by suddenly stopping
the agitation which maintains the solid matter in suspension to effect
the formation of a suitable graduated filter bed, substantially as
described, the effect being to admit of rapid filtration and to leave the
material in a state pervious to steam, thereby enabling the bi-sulphide
of carbon or other solvent to be effectually removed from the residual
matter by the direct injection of steam.
4th. The method of treating the materials in the extractor by suc-
cessive washings of bi-sulphide of carbon or other solvent percolating
downwards, drawing off each such washing as completely as possible 1
from the residuum before admitting the supply of solvent for the
succeeding washing, collecting the first washing separately for distillation,
and utilizing the subsequent washings to effect the first washing of the
succeeding batch of material in the extractor, substantially as described.
5th. The arrangement of parts constituting that portion of the
apparatus which provides for the air which has been brought into
contact with the solvent and become saturated with its vapour, being
stored in a gas holder and afterwards returned to the apparatus for the
purpose of expelling the unsaturated air so as to prevent further waste of
solvent, substantially as described.
6th. The general arrangement of apparatus constructed and arranged
substantially as and for the purposes herein described and shewn in the
Drawings.
In witness whereof, I, the said Samuel Henry Johnson, have
hereunto set my hand and seal, this Twenty-fourth day of June, 1
in the year of our Lord One thousand eight hundred and seventy-