IMPROVEMENTS IN THE PURIFICATION OF WATER AND IN PROVISIONAL SPECIFICATION THE MEANS AND APPARATUS EMPLOYED FOR THAT PURPOSE
Year: 1873

page_text: LETTERS PATENT to Gustav Bischof, of the Andersonian University,
in the City of Glasgow, Professor of Technical Chemistry, for the
Invention of "IMPROVEMENTS IN THE PURIFICATION OF WATER AND IN
PROVISIONAL SPECIFICATION left by the said Gustav Bischof at the
Office of the Commissioners of Patents, with his Petition, on the
3rd January 1873.
I, GUSTAV BISCHOF, of the Andersonian University, in the City of
Glasgow, Professor of Technical Chemistry, do hereby declare the nature
of the said Invention for "IMPROVEMENTS IN THE PURIFICATION OF WATER
AND IN THE MEANS AND APPARATUS EMPLOYED FOR THAT PURPOSE," to be as
follows:-
When purifying water by means of spongy iron, according to the
Invention for which Letters Patent were granted to me on the 19th
September 1870, No. 2516, a certain small quantity of the iron is
dissolved, probably by the carbonic acid contained in the water, which

page_text: iron after being oxidized by atmospheric oxygen is spontaneously
deposited in the water as hydrated oxide.
For the purpose of applying this process of purifying water to filters
of small dimensions for domestic and other purposes, and also sometimes
for larger filters, it is however desirable that the deposition of the
dissolved iron should be regulated and accelerated, and according to my
present Invention I accomplish this in the following manner :-The
water which has been filtered through a layer of spongy iron, and which
contains some iron in solution, is made to pass through a layer of finely
pulverized marble or ordinary limestone, by which the iron is readily
precipitated and retained as hydrated oxide.
In adapting this combined process for use in filters of small dimensions,
I construct such filters in the following manner:-The spongy iron,
through which the water to be filtered or purified first passes, is contained
in a vessel with perforated bottom situated in the upper part of the filter
casing. The spongy iron should be coarsely pulverized to about the size
of lentils, but I prefer placing on the top of the layer of coarse spongy
iron a layer some two inches thick of finer spongy iron, which, besides
its chemical action, acts also as a mechanical strainer for retaining solid
suspended impurities in the water. The spongy iron, after having once
been moistened with water, must not be again exposed to the air as
otherwise it rapidly oxidizes and loses more or less of its purifying
power. To prevent this I surround the vessel containing the spongy
iron by another vessel with closed bottom and of slightly larger
dimensions, which is provided with an overflow pipe at the top, an inch
or two above the level of the spongy iron. Thus the water, after passing
through the vessel containing the spongy iron, ascends from the per-
forated bottom through the annular space between the inner and
outer vessel and escapes through the overflow pipe. Thus should the
water supply to the filter be stopped a sufficient quantity of water will
always be retained in the inner vessel to keep the spongy iron covered
thereby. The overflow pipe passes down the outer side of the outer
vessel and underneath the same to the centre of its bottom, whence the
water issues from the pipe on to a layer of marble or limestone placed
upon a perforated bottom situated below the above named vessels in the
filter casing; and after filtering. through the marble or limestone the
water..is collected in a chamber or reservoir below, whence it can be
drawn off by a tap as required.

page_text: Instead of surrounding the vessel containing the spongy iron with
another vessel as above described, the former may have a closed bottom
beneath its perforated bottom, and the space between the two is made to
communicate with a pipe, which passes up the outer side of the vessel
to slightly above the level of the spongy iron. Here the pipe com-
municates with another pipe, which passes from nearly the top of the
outside of the spongy iron vessel down to the centre of its closed bottom.
The latter pipe is open at the top and bottom, as if it were closed at the
top it would act as a syphon and drain off the water from the spongy
iron. A cock or screw tap is provided at the lower end of the latter
pipe, by means of which the flow of the water through the spongy iron
can be regulated, and whence the water issues on to the layer of marble
or limestone as above described.
Instead of enclosing the spongy iron and the marble or limestone in
one and the same casing they may be contained in separate casings; that
containing the spongy iron being placed at a higher level than but not
necessarily immediately above that containing the marble or limestone,
and the overflow pipe from the spongy iron vessel is extended so as to
communicate with the vessel containing the marble or limestone; or the
two vessels may be on the same level, and the water be drawn off from
and made to pass through the two vessels by means of a syphon attached
to the vessel containing the marble or limestone or otherwise.
The two vessels may either be immersed into a reservoir containing the
water to be purified, or otherwise supplied with water. Instead of the
limestone or marble, animal charcoal may be employed for retaining the
iron from the water.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Gustav Bischof in the Great Seal Patent Office
on the 26th June 1873.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, GUSTAV
BISCHOF, of the Andersonian University, in the City of Glasgow, Pro-
fessor of Technical Chemistry, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Third day of January, in the year

page_text: of our Lord One thousand eight hundred and seventy-three, in
the thirty-sixth year of Her reign, did, for Herself, Her heirs and
successors, give and grant unto me, the said Gustav Bischof, Her
special license that I, the said Gustav Bischof, my executors, adminis-
trators, and assigns, or such others as I, the said Gustav Bischof, 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 "Im-
PROVEMENTS IN THE PURIFICATION OF WATER AND IN THE MEANS AND APPARATUS
EMPLOYED FOR THAT PURPOSE," upon the condition (amongst others)
that I, the said Gustav Bischof, 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 Gustav Bischof, 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 :-
When purifying water by means of spongy iron, according to the
Invention for which Letters Patent were granted to me on the 19th
September 1870, No. 2516, a certain small quantity of the iron is
dissolved, probably by the carbonic acid contained in the water, which
iron, after being oxidized by atmospheric oxygen, is spontaneously
deposited in the water as hydrated oxide.
For the purpose of applying this process of purifying water to filters
of small dimensions for domestic and other purposes, and also sometimes
for large filters, it is however desirable that the deposition of the
dissolved iron should be regulated and accelerated, and according to my
present Invention I accomplish this in the following manner :-'
_The
water which has been filtered through a layer of spongy iron, and which a
contains some iron in solution, is made to pass through a layer of finely
pulverized marble or ordinary' limestone, by which the iron is readily
precipitated and retained as hydrated oxide.

page_text: regulated, and whence the water issues on to the layer of marble or
limestone as above described.
Instead of enclosing the spongy iron and the marble or limestone in
one and the same casing, they may be contained in separate casings; that
containing the spongy iron being placed at a higher level than but not
necessarily immediately above that containing the marble or limestone,
and the overflow pipe from the spongy iron vessel is extended so as to
communicate with the vessel containing the marble or limestone, or
the two vessels may be on the same level, and the water be drawn off
from and made to pass through the two vessels by means of a syphon
attached to the vessel containing the marble or limestone or otherwise.
The two vessels may either be immersed into a reservoir containing
the water to be purified, or otherwise supplied with water. Instead of
the limestone or marble, other calcareous bodies or animal charcoal may
be employed for retaining the iron from the water.
Having thus described the nature of my Invention, and in what
manner the same is to be performed, I claim,―
First. The use of limestone, marble, or animal charcoal for retaining
iron from water purified by being passed through spongy iron, sub-
stantially as herein described.
Second. The use of a filter whereby water is purified by being first
passed through spongy iron and then through limestone, marble, or
animal charcoal, the filter being so arranged that the spongy iron is
always covered with water, substantially as herein described.
In witness whereof, I, the said Gustav Bischof, have hereunto set
my hand and seal, this Twenty-fourth day of June, in the year
of our Lord One thousand eight hundred and seventy-three.