IMPROVEMENTS IN THE MANUFACTURE OF A FILTERING MEDIUM EAD THE PURIFICATION OR WITD AND OTHED LIQUIDS
Year: 1877

page_text: LETTERS PATENT to Edward Johnson, of No. 3, Eliot Cottages, Blackheath, in
the County of Kent, Sanitary Engineer, and James Robey, of No. 2, South
Crescent, Greenwich, in the same County of Kent, Sugar Refiner, for the
Invention of "IMPROVEMENTS IN THE MANUFACTURE OF A FILTERING MEDIUM
EAD THE PURIFICATION OR WITD AND OTHED LIQUIDS"
PROVISIONAL SPECIFICATION left by the said Edward Johnson and James
Robey at the Office of the Commissioners of Patents on the 20th September
1877.
EDWARD JOHNSON, of No. 3, Eliot Cottages, Blackheath, in the County of Kent,
Sanitary Engineer, and JAMES ROBEY, of No. 2, South Crescent, Greenwich, in the
same County of Kent, Sugar Refiner. "IMPROVEMENTS IN THE MANUFACTURE OF A
FILTERING MEDIUM FOR THE PURIFICATION OF WATER AND OTHER LIQUIDS."
This Invention has for its object the production and manufacture of a filtering
medium, which is intended to supersede advantageously the use of the expensive
material called animal charcoal in the filtration of potable waters, and other liquids.
For this purpose we take baked clay ground to a granular form of various sizes,
according to the nature of the liquid to be filtered.
It is preferred that the baked clay should be in as porous a condition as can be
obtained.
For the purposes of economy of manufacture we prefer using waste baked clay,
such as the broken ware of the tobacco-pipe makers, the waste and breakage of the
porous battery cell makers, the broken ware called bisque, or biscuit, of the earthen-
ware and china manufacturers, or any kind of baked clay, that which is most
porous being preferred, as well as that which contains some iron.
In the absence of such waste material any suitable clay may be baked, and
employed for the purposes of this Invention.
Having thus obtained baked clay in a granular form we now proceed to the next

page_text: process, which we term the carbonising process, and which is accomplished by two
distinct methods, one, which we term the dry method, and the other the wet
method.
The dry process consists in mixing the above granular material with any kind of
vegetable matter, such as leaves, fragments of wood, dried grass, sawdust; the waste
vegetable material of the dyers' and tanners' processes, such as logwood, oak bark,
gall nuts, valonias, or tan, and also coal dust, or any kind of vegetable waste, and
then placing the mixture in retorts to be heated, preferably, to a red heat, until all
gaseous emanations cease.
It will now be found that the granular baked clay is thoroughly carbonised
throughout its substance, and forms a filtering medium superior to animal charcoal
for the removal of albumenoid ammonia. Amongst the clay thus carbonised
will be found a quantity of vegetable charcoal, which being of much lighter
specific gravity can be separated by a blowing machine, as chaff is separated from
wheat.
The separation can also be accomplished by means of water. This light vegetable
charcoal is a bye product of considerable value for many purposes.
Any of the usual carbonising apparatus may be used, such as the revolving
cylinders of the sugar refiners, the D retorts of the gas works, and the primitive
cast-iron pot kiln of the first animal charcoal manufacturers. The last named will
make the best and purest quality of filtering material for domestic purposes, but
the revolving cylinders, however, will accomplish the carbonization much more
economically, whilst the use of the gas works retort would enable the maker to
obtain a bye product of pyroligneous acid when sawdust is the vegetable matter
used.
The wet process consists in steeping the granular baked clay in any organic
solution, such as solution of treacle, solutions of grass, leaves, logwood, bark, tan,
coal tar, or any liquid containing organic matters in solution.
Instead of steeping the granular baked clay in any such solution, such solutions
may be passed through beds of it after the manner of filters.
After either of these methods has been used the granular baked clay thus treated is
set aside to dry previous to being placed in any of the before-mentioned retorts, and
brought to a full red heat, as in the dry process already described. This granular
baked clay will now be found to be thoroughly carbonized, as in the dry process just
described, but in this case there is no separation required, there being no foreign
particles intermixed.
The filtering medium produced in accordance with this Invention is placed in
any suitable receptacle, and employed for the operation of filtering, as well
understood

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Edward Johnson and James Robey in the Great Seal Patent Office
on the 20th March 1878.
EDWARD JOHNSON, of No. 3, Eliot Cottages, Blackheath, in the County of Kent,
Sanitary Engineer, and JAMES ROBEY, of No. 2, South Crescent, Greenwich, in the
same County of Kent, Sugar Refiner. "IMPROVEMENTS IN THE MANUFACTURE OF A
FILTERING MEDIUM FOR THE PURIFICATION OF WATER AND OTHER LIQUIDS."
Our said Invention has for its object the production and manufacture of a
filtering medium, which is intended to supersede advantageously the use of the
expensive material called animal charcoal in the filtration of potable waters and
other liquids. For this purpose we take baked or fired clay ground to a granular
form of various sizes, according to the nature of the liquid to be filtered.
It is preferred that the baked or fired clay should be in as porous condition as it
can be obtained.
For the purposes of economy of manufacture we prefer using waste baked or fired
clay, such as the broken ware of the tobacco-pipe makers, the waste and breakage of the
porous battery cell makers, the broken ware called bisque, or biscuit, of the earthen-
ware and china manufacturers, or any kind of baked or fired clays, that which is
most porous being preferred, as well as that which contains some proportion of
iron.
In the absence of such waste material any suitable clay may be baked or dried,
either by natural or artificial means, and employed for the purposes of our said
Invention.
In the two latter cases the clay is only required to be so far dried as to be capable
of being pulverised in the desired granular form.
Having thus obtained baked or fired or dried clay in a granular form we now proceed
to the next process, which we term the carbonising process, and which is accomplished
by two distinct methods; one which we term the "dry" method, and the other the
"wet" process.
The dry process consists in mixing the above granular material with any kind of
vegetable matter, such as leaves, fragments of wood, dried grass, sawdust, the wasto
vegetable material of the dyers' and tanners' processes, such as logwood, oak bark,
gall nuts, valonias, or tan, and also coal dust, or any kind of vegetable waste, and
then placing the mixture in retorts to be heated, preferably, to a red heat, until all
gaseous emanations cease.
In some cases we also carbonize the baked or fired, or naturally dried clay, after
granulation, by means of the vapours or gases of vegetable matters or coal, and for
this purpose the whole of the vegetable matters or the coal may be placed in a body
at the bottom of a crucible or retort, and the granular material in a body above the
vegetable matters or coal.
Upon the application of a red heat the granular material will be found to be
sufficiently carbonised for many purposes, although we prefer the intermingling
process herein-before described; or, the vegetable matters or coal may be placed
in a separate vessel or retort, and the granular baked, fired, or dried clay in another
similar vessel or retort, the two vessels or retorts being connected by means of a
suitable pipe.
Upon the requisite degree of heat being applied to the vessel or retort containing
the vegetable matters or coal, the vapours or gases evolved therefrom will pass
through the pipe into the vessel or retort containing the granular material to
which also heat should be applied, thus carbonising the latter sufficiently for many
purposes.
In order to produce this result the heat applied to the two vessels or retorts
should be a full red heat; as before mentioned, however, we prefer that in all cases
the vegetable matters or coal should be mingled with the granular material.
It will now be found that the granular baked or fired clay is thoroughly

page_text: carbonised throughout its substance, and forms a filtering medium superior to
animal charcoal for the removal of albuminoid ammonia. Amongst the clay thus
carbonised will be found a quantity of vegetable charcoal, which being of much
lighter specific gravity can be separated by a blowing machine, as chaff is separated
from wheat.
The separation can also be accomplished by means of water. This light vegetable
charcoal is a bye product of considerable value for many purposes.
Any of the usual carbonising apparatus may be used, such as the revolving
cylinders of the sugar refiners, the D retorts of the gas works, and the primitive
cast-iron pot kiln of the first animal charcoal manufacturers. The last named will
make the best and purest quality of filtering material for domestic purposes, but the
revolving cylinders will also accomplish the carbonization much more economically,
whilst the use of the gas works retort will enable the maker to obtain a bye
product of pyroligneous acid when sawdust is the vegetable matter used.
The "wet" method consists in steeping the granular baked or fired clay, such as
is herein-before mentioned, in any organic solution, such as a solution of treacle,
solutions of grass, leaves, logwood, bark, tan, coal tar, or any liquid containing
organic matters in solution. The last-described method is not, however, applicable
to merely dried clay.
Instead of steeping the granular baked or fired clay in any such solution, such
solutions may be passed through beds of such baked or fired clay after the manner
of filters.
After either of the above-described methods has been carried out the granular
baked or fired clay, which has been thus treated is set aside to dry, previous to
being placed in any of the before-mentioned retorts, and brought to a full red heat,
as in the dry process already described. This granular baked or fired clay will now
be found to be thoroughly carbonised, as in the dry process before described, but in
the case of the wet method no separation is required, there being no particles of
foreign substances intermixed.
The filtering medium produced in accordance with our said Invention is placed
in any suitable receptacle, and employed for the operation of filtering, as well
understood.
Having thus declared and ascertained the nature of our said Invention, and in
what manner the same is to be performed, we would observe in conclusion that
what we consider novel and original, and therefore claim as the Invention secured
to us by the said herein-before in part recited Letters Patent, are,-
-
First. The manufacture of a filtering medium by the process herein-before called
the "dry process," substantially as herein-before described and set forth.
And, Secondly. The manufacture of a filtering medium by the process herein-
before called the "wet process," substantially as herein-before described and set
forth.
In witness whereof, I, the said Edward Johnson, on behalf of myself and the
said James Robey, have hereunto set my hand and seal, this Twentieth day