IMPROVEMENTS IN MEANS AND APPARATUS FOR PURIFYING GAS, AND IN THE PREPARATION AND TREATMENT OF OXIDES OF IRON TO BE USED IN SUCH PURIFICATION OR FOR OTHER PURPOSES
Year: 1859

page_text: LETTERS PATENT to Frank Clarke Hills, of Deptford, in the County of
Kent, Manufacturing Chemist, for the Invention of "IMPROVEMENTS IN
MEANS AND APPARATUS FOR PURIFYING GAS, AND IN THE PREPARATION AND
TREATMENT OF OXIDES OF IRON TO BE USED IN SUCH PURIFICATION OR FOR
OTHER PURPOSES."
Sealed the 10th February 1860, and dated the 17th December 1859.
PROVISIONAL SPECIFICATION left by the said Frank Clarke Hills at
the Office of the Commissioners of Patents, with his Petition, on the
17th December 1859.
I, FRANK CLARKE HILLS, of Deptford, in the County of Kent, Manu-
facturing Chemist, do hereby declare the nature of the said Invention for
"IMPROVEMENTS IN MEANS AND APPARATUS FOR PURIFYING GAS, AND IN THE PRE-
PARATION AND TREATMENT OF OXIDES OF IRON TO BE USED IN SUCH PURIFICATION, OR
FOR OTHER PURPOSES," to be as follows:-
My improvements relate to purifying gas by oxide of iron, and my first
process is an improvement on a former process for which I obtained Letters
Patent, the said Patent having for title "Improvements in Manufacturing and
Purifying certain Gases, and in Preparing certain Substances for Purifying
the same," and bearing date the 24 day of January, 1852, No. 13,912
The said process was to mix with the gas to be purified a small per-centage

page_text: of atmospheric air. The air was mixed with the gas for the purpose of
renovating the oxide at the same time that the oxide purified the gas; but it
was found that the deposition of sulphur among its particles clogged the oxide,
and tended to render it impervious to the gas; and the object of the present
improvement is to prevent such clogging, and to make the oxide last as long
as possible in the purifier, without the necessity for its being removed. To
effect this object I employ a circular vessel which may be similar to a dry
lime purifier, with a grating or gratings to support the oxide mixed or unmixed
with other material in the usual way. A vertical shaft or spindle is placed in
the centre of the purifier furnished with arms or stirrers after the manner of
a pug mill, and which shaft is to be caused to rotate slowly, continuously, or
at intervals sufficient to keep the material stirred up while in the purifier so
as to present fresh surfaces to the gas and to the air admitted with it, and also
to keep it pervious and open, so that the gas may easily pass through it. If
about 4 or 5 per cent. of air is mixed with the gas, it ought to keep the
oxide material renovated as fast as it becomes deteriorated by purifying the
gas from sulphuretted hydrogen, and will thus last a very long time in the
purifier, and save the labor of frequently taking the said oxide material out,
and also save the space necessary for its frequent renovation when taken out
of the purifier for exposure to the air. Any deterioration in the illuminating
power of the gas caused by mixing the air with it may be made up by using a
sufficient quantity of Cannel coal or Bog Head coal; instead of admitting the
gas into the bottom of the purifier as usual, and passing it up through the
purifying material, I prefer admitting it above the purifying material, and
causing it to descend through it, for the material is not then so disposed to
clog on the gratings.
My second improvement relates to a method of renovating oxide of iron
when it is taken out of the gas purifiers after it has become inert. I employ
what I term an oxidizing vessel, a convenient form of which is a long tube or
cylinder of any required size proportioned to the quantity of material to be
treated, say 20 or 30 feet long by 2 or 3 feet diameter placed a little higher
at one end than at the other, and made to revolve slowly. The material to be
oxidized is to be admitted into the higher end of the tube by means of a
hopper in such quantities that the tube may be kept about half or two-thirds
full for its whole length; a current of atmospheric air is to be caused to pass
through the tube to oxidize the iron, and which air may afterwards be passed
through a condenser to collect any ammonia the material may contain, and
then over a fire to destroy any impurities that are drawn off from the
material. Steam also may be admitted into the oxidizing tube when the

page_text: material oxidises slowly to keep up a proper heat. By the rotation of the
tube the material will be constantly tumbling over from the upper part to the
lower part, and will thus become thoroughly exposed to the air, and be very
rapidly oxidized. The oxidizer should be placed at such an incline, and the
material admitted into it should be so regulated that it may become suffi-
ciently oxidized by the time it gets from one end of the tube to the other.
Instead of causing the tube to rotate, a shaft may be passed through the tube
with stirrers on it, and which being caused to rotate will stir up the material,
and expose it to the air. A continuous process of purification and renovation
may be also made without admitting air into the purifier with the gas by
having the top and bottom of the purifier made conical, and introducing the
gas through gratings round the bottom part of the sides of the purifier, and
with a system of valves and an exhauster a certain quantity of oxide material
may be admitted and drawn out of the purifier at intervals while the purifier
is at work. By means of elevators and hoppers the material may be conveyed
to the oxidizing vessel, and from thence it may be conveyed to the purifier
again. To prepare oxide of iron fit for purifying gas, I take cast-iron borings
or turnings and grind them as fine as possible either by means of edge runners or
otherwise. After being ground, the powder or finest portions are to be sifted
out. The fine iron powder thus obtained is to be uniformly wetted with very
weak sulphuric, muriatic, nitric, or acetic acid, preferably hot, or with hydro-
sulphuret of lime, or hydro-sulphuret of soda, or with a mixture in water of
sulphur and salammoniac. The iron is then to be made into heaps or to be
spread on the ground in quantities sufficiently thick to heat by its exposure to
the air for oxidation, but it must not be allowed to get too hot. It should be
occasionally stirred or turned over until it becomes cool, when it is to be again
damped as at first, and by exposure to the air it will again become heated.
This process of damping the iron powder, and exposing it to the air is to be
repeated until it becomes sufficiently oxidized. As soon as a considerable
quantity of oxide of iron is formed it may be washed off and used, and the
unoxidized iron may be re-ground, and the same process as just described be
repeated. Instead of oxidizing the iron and damping it as described, and.
spreading it on the ground to expose it to the air, it may be damped in any.
convenient way in the oxidizing tube before described, and which, by its
rotation, will better expose the particles of iron to the air to be oxidized.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said Frank Clarke Hills in the Great Seal Patent Office on the
16th June 1860.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, FRANK
CLARKE HILLS, of Deptford, in the County of Kent, Manufacturing Chemist,
send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Seventeenth day of December, in the year of our
Lord One thousand eight hundred and fifty-nine, in the twenty-third year of
Her reign, did, for Herself, Her heirs and successors, give and grant unto
me, the said Frank Clarke Hills, Her special licence that I, the said Frank
Clarke Hills, my executors, administrators, and assigns, or such others
as I, the said Frank Clarke Hills, 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 "IMPROVE-
MENTS IN MEANS AND APPARATUS FOR PURIFYING GAS, AND IN THE PREPARATION
AND TREATMENT OF OXIDES OF IRON TO BE USED IN SUCH PURIFICATION, OR FOR
OTHER PURPOSES," upon the condition (amongst others) that I, the said Frank
Clarke Hills, 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 Frank Clarke Hills, 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 improvements relate to purifying gas by oxide of iron, and my first
process is an
improvement on a former process, for which I obtained Letters
Patent, the said Patent having for title "Improvements in Manufacturing
and Purifying certain Gases, and in Preparing certain Substances for
Purifying the same" and bearing date the Twenty-fourth day of January, One
thousand eight hundred and fifty-two, No. 13,912.
The said process was to mix with the gas to be purified a small per-centage
of atmospheric air. The air was mixed with the gas for the purpose of reno-

page_text: vating the said oxide material, at the same time that the oxide purified the gas,
but it was found that the deposition of sulphur among its particles clogged the
oxide, and tended to render it impervious to the gas; and the object of the
present improvement is to prevent such clogging, and to make the oxide last
as long as possible in the purifier without the necessity for its being removed.
To effect this object, I prefer to cause the gas to pass downwards through the
oxide purifying material in the purifier, instead of upwards as is usually done,
and I take care that no tarry matter comes forward with the gas. By thus
directing the gas the upper portion of the purifying material takes the most
sulphur from the gas, and has the greatest tendency to become clogged, but
being at the upper part of the purifier, it is more easily stirred or broken up
than when the gas is admitted at the lower part. The purifying material I
prefer to be placed in circular purifiers, similar to those used for dry lime.
A vertical shaft or spindle is placed in the centre of each purifier, furnished
with one or more horizontal arms or stirrers extending nearly to the sides of
the purifier. When the purifier is above eight or ten feet in diameter, one or
two arms will be found sufficient, as in very large purifiers a greater number
would be difficult to move. If one arm only is used, it may be furnished with
teeth like a rake to break up the surface of the material, and the arm itself
may be above the surface of the material, so as to offer as little resistance as
possible. The arm or arms may be a few inches wide according to the size
of the purifier, and (if there are more than one) should be placed nearly one
above another, about six or eight inches apart, the top one being about its own
breadth in advance of the one below it, and that again the same distance in
advance of the next lower one, as shewn in Figure 4 of the Drawings. In
cases where the material becomes dense or heavy, the arms may be radiating
at such an angle that the outer end of each shall be six or eight incbes in
advance of the next lower one, as the said arms will then have less tendency
to push the material forward. In either of these arrangements I form the
arms thin at the front edge so that they may cut through the oxide material,
and thick at the back to give strength to them, and they are set sloping-so
that the top side of each may form an angle, by preference of about fifteen to
twenty degrees, so as to lift the material a little as they are carried round by
the spindle. The outer end of the top arm should be supported by a tie rod
from the upper part of the spindle to prevent its deflecting, and the outer ends
of the lower arms, when there are more than one, should be supported by thin
knife-shaped tie rods or bars from one blade to another, so as to prevent
deflection in any of them.

page_text: I will now describe more minutely the apparatus used in this part of my
Invention, reference being had to Figures 1, 2, 3, and 4, of the accompanying
Drawings.
Figure 1 is a side elevation of a purifier constructed according to my In-
vention; Figure 2 is a section of the same; and Figure 3 is a plan of the
same, shewing the cover removed. Part of the grating R is also shewn
removed, in order to shew more clearly the bevel wheels which actuate the
stirrers. The same letters indicate the same parts in Figures 1, 2, 3, and 4.
A, A, is a circular vessel containing the purifying material; the said vessel is
provided with a water joint B, and cover C; R is a grating which supports the
purifying material; D is the gas inlet main; d is an air pipe communicating
therewith; E is a passage through which the gas and air pass from the main
D to the purifier A; F is the gas outlet main or exit pipe; G is a vertical
shaft (shown by dotted lines in Figures 2 and 4). The shaft G rotates in
bearings g', g², carrying with it the arms or stirrers H, H2, H3. The said
arms are fastened to the shaft G by keys or wedges, or other suitable means,
and are strengthened and prevented from being deflected by the knife-shaped
rods or bars h1, h2, h3, and tie rod I; P, P, are rods which support the
bearing g'; K, K, are rings which serve to keep the arms H', H2, H3, at the
proper distance apart; L is a bevel toothed wheel keyed to the shaft G; M is
a pinion gearing into the wheel L. The pinion M is actuated by the shaft N,
and handle O. The shaft N works in the bearing n, and stuffing box o. The
apparatus is supported by piers Q, Q.
The operation of the apparatus is as follows:-The vessel A is filled or
nearly filled with the oxide material in the usual way. The top of the vessel
is then closed by the cover C. From one to five per cent. of atmospheric air
is to be thoroughly mixed with the gas to be purified. This may be effected
by drawing the air through a meter to regulate the quantity admitted by the
pipe d to the inlet main D, passing along which, it will become intimately
mixed with the gas. The gas and air pass from the inlet main D through the
passage E to the purifier A, and after passing through the oxide material leave
the purifier by the exit pipe F. During the process of purification, the shaft G
is caused to rotate slowly, either continuously or at intervals. By this rotation
of the shaft G and stirrers H1, H2, H3, the oxide material will be stirred and
broken up, fresh surfaces will be exposed, and the said material will be kept
more pervious and open, and will be less liable to be clogged by the deposition
of sulphur, so that the gas and air easily pass through it.
In cases where circular purifiers cannot be conveniently got, square or any

page_text: other shaped purifiers may be used, and instead of keeping the material stirred
and broken up by the spindle and arms before described, it may be kept
pervious and open by means of rakes or such like implements drawn over the
surface of the material in any convenient manner.
In cases where the mixed gas and air cannot be conveniently passed down-
wards through the material in the purifier, it may be passed upwards as usual,
but in this case the gratings which support the material should be covered
about three or four inches thick, with tan or coarse sawdust or such like
material, which not having any oxide of iron mixed with it will not become
clogged.
If about four or five per cent. of air is mixed with the gas, it ought in
most cases to keep the oxide material renovated as fast as it becomes deterio-
rated, by purifying the gas from sulphuretted hydrogen. The oxide material
will thus last a very long time in the purifier, and the labor of frequently taking
out the said oxide material, and also the space necessary for its frequent reno-
vation, when taken out of the purifier for exposure to the air will be saved.
Any deterioration in the illuminating power of the gas caused by mixing the
air with it, may be made up by using a sufficient quantity of Cannel coal or
Bog Head coal in the manufacture of the said gas.
of the same.
A is a long
to be treated,
My second improvement relates to a method of renovating oxide of iron
taken out of the gas purifiers after it has become inert. For this purpose I
employ what I term an oxidizing vessel, the form of which is represented in
Figures 5, 6, and 7 of the accompanying Drawings, Figure 5 being a side
elevation; Figure 6, a section of the same; and Figure 7, a plan
The same letters indicate the same parts in Figurs 5, 6, and 7.
tube or cylinder of a size proportioned to the quantity of material
say twenty or thirty feet long by two or three feet in diameter. The tube A
turns upon axes B', B², which pass through transverse bars C, C, and are
secured by nuts and screws b, b. The axes B³, B², rotate in bearings D¹, D³.
E is a band wheel fixed to the axis B₁; F is a hopper secured to the framing
G, G, of the apparatus by a flange H; I is a steam pipe. The framing G, G,
is supported at one end by trunnions g, g, resting in the plummer block J, and
at the other end by the screw jack K, by which the said end can be raised or
lowered, as required. Additional support is afforded to the tube A by friction
wheels L, L, which are fixed at suitable intervals upon the framing G, G, and
grooved bands M, M, which are secured to the exterior of the said tube; N is
the bed plate upon which the apparatus rests.
The action of the apparatus is as follows:-The material to be oxidized is
to be admitted into the tube A by the hopper F in such quantities that the

page_text: tube may be kept about half or two-thirds full for its whole length. A current
of atmospheric air is to be caused to pass through the tube to oxidize the iron,
which air may afterwards be passed through a condenser to condense any
ammonia which may have been carried off from the material, and thence over
a fire to destroy any impurities which may have been at the same time drawn
off from the said material. Steam may be admitted into the oxidizing tube
by the pipe I when the material oxidizes slowly to keep up a proper beat. The
tube A is caused to rotate slowly by the band wheel E. By this rotation of
the tube the material will be kept constantly tumbling over from the upper to
the lower part of the said tube, and will thus be thoroughly exposed to the air
and become rapidly oxidized. The oxidizing vessel should be placed at such
an incline and the material admitted should be so regulated that it may be
sufficiently oxidized during its passage through the tube.
I sometimes modify this part of my Invention in the following manner :-
Instead of causing the tube to rotate I pass a shaft through it having stirrers
thereon, which will lift up the material; the said shaft being caused to rotate
will continuously stir and lift up the material and expose it to the air. As the
general arrangement of this apparatus differs in no essential respect from that
last described, I do not think it necessary further to describe the same. To
prepare oxide of iron fit for purifying gas, I take cast-iron borings or turnings
and grind them as fine as possible either by means of edge runners or other-
wise; after being ground the powder or finest portions are to be sifted out, and
the fine iron powder thus obtained is to be uniformly wetted with a very weak
olution of sulphuric or muriatic or nitric or acetic acid, preferably hot. Only
just sufficient acid need be added to the water with which the iron is wetted to
make it slightly acidulous, say, from one to five per cent. Instead of wetting
the iron powder with either of the weak acid solutions before named, it may be
wetted with a solution of hydrosulphuret of lime, or of hydrosulphuret of soda,
or with a mixture in water of sulphur and a little salammoniac and as much of
either of the said solutions may be added as it will absorb. The mixture may
then be made into heaps or be spread on the ground in quantities sufficiently
thick to heat and oxidize by means of the air and water and other ingredients
mentioned, but it must not be allowed to get too hot; it should be occasionally
stirred or turned over until it becomes cool, when it is to be again damped as
at first and by exposure to the air it will again become heated. This process
of damping the iron powder with either of the ingredients above mentioned,
and exposing it to the air, is to be repeated until it becomes sufficiently oxi-
dized. As soon as a considerable quantity of oxide of iron is formed it
may
be
washed off for use, and the unoxidized iron may be re-ground, and the same

page_text: process, as just described, may be repeated. Instead of oxidizing the iron and
damping it as described, and spreading it on the ground to expose it to the air
it may be damped in any convenient way in the oxidizing tube before described.
Having thus described the nature of my said Invention and the means which
I adopt in carrying the same ito effect, I would have it understood that I do
not confine myself to the precise details referred to, as these may be varied
without departing from the peculiar character of my improvements; but what
I claim is,
Firstly, the adaptation or combination of means and apparatus for the
purification of gas by the aid of oxide of iron, substantially as explained.
Secondly, I claim the mode of renovating oxide of iron used in the puri-
fication of gas, or for other purposes, substantially as explained.
Thirdly, I claim the means of obtaining hydrated oxides of iron, substan-
tially as explained.
In witness whereof, I, the said Frank Clarke Hills, have hereunto set my
hand and seal, this Fourteenth day of June, in the year of our Lord
One thousand eight hundred and sixty.
Witness,
H. H. MURDOCH.
F. C. HILLS. (L.S.)