IMPROVEMENTS IN FILTERS FOR PURIFYING WATER
Year: 1878

page_text: LETTERS PATENT to Albert James Bernays, Ph. Dr., F.C.S., Professor of
Chemistry at Saint Thomas' Hospital, Lambeth, for the Invention of
"IMPROVEMENTS IN FILTERS FOR PURIFYING WATER.”
Sealed the 31st Mow 1878 and dated the 13th March 1878.
PROVISIONAL SPECIFICATION left by the said Albert James Bernays at the
Office of the Commissioners of Patents on the 13th March 1878.
ALBERT JAMES BERNAYS, Ph. Dr., F.C.S., Professor of Chemistry at Saint
Thomas' Hospital, Lambeth. "IMPROVEMENTS IN FILTERS FOR PURIFYING WATER."
My Invention consists in using for the purpose of purifying water a reduced
oxide of manganese, combined with charcoal, obtained by heating to a high tempe-
rature in covered vessels a mixture of commercial powdered black oxide of manga-
nese or pyrolusite with charcoal and oil, or lard or treacle. The charcoal is
preferably used in the granular form, and may be animal or vegetable, or of any of
the known varieties, as found most serviceable for the different waters under treat-
ment.
Or I employ a charcoal impregnated with the crude chloride of manganese
obtained in the manufacture of chlorine, and known as "chlorine residue," then
dried and heated to a high temperature in covered pots till the volatile matters are
expelled.
The chloride of manganese may be previously purified if necessary by precipi-
tating the impurities by chalk or lime water in due proportion. The charcoal, after
soaking in the manganese liquor, may be afterwards treated with milk of lime or
lime water to precipitate oxide of manganese within its pores, then dried and
ignited away from air as above.
The filtering bed should be prepared as follows:-Upon a diaphragm of stone-
ware or other suitable material pierced with a large number of small holes is placed
a layer of "glazed grit," or stoneware granulated and salt glazed; over this a
stratum of thoroughly washed sand of a medium degree of fineness, above this the
F¬

page_text: manganese charcoal prepared by any of the ways before mentioned, then a second
layer of sand, and finally more glazed grit, surmounted by another perforated
diaphragm of stoneware and a chamber for the water to be filtered.
The filtering media should be thoroughly washed through in situ with good
ordinary water till all turbidity or earthiness is removed.
The upper and lower diaphragms should be slightly concave on their upper
surfaces, and the chamber for filtered water should be so sloped towards the tap as
to allow all the water to be drawn off, with the object of preventing any stagnation
of the water in the filter.
The thickness of the layers and the rapidity of filtration will depend obviously on
the character of the water to be purified.
The layers of filtering media may also be arranged in separate vessels of suitable
construction within the same filter, so as to allow of the separate renewal of any one
of them when necessary without disturbing the others.
In the case of very turbid waters the upper diaphragm may be made with only
one aperture in the centre, closed by a plug of pumice stone or very porous earthen-
ware to stop the greater part of the solid impurities. This plug will fulfil the office
of the sponge in ordinary filters without introducing an organic material, and may
be replaced as often as it is found to be clogged with solid impurities.
The lower chamber for filtered water should have a narrow channel in the case of
the filter communicating with the atmosphere so as to keep the water as thoroughly
aerated as possible.
The entire method of filtration may be applied with the ordinary modifications to
cisterns and other forms of water supply.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Albert James Bernays in the Great Seal Patent Office on the 13th
September 1878.
ALBERT JAMES BERNAYS, Ph. Dr., F.C.S., Professor of Chemistry at Saint
Thomas' Hospital, Lambeth. “IMPROVEMENTS IN FILTERS FOR PURIFYING WATER."
My Invention consists in using for the purpose of purifying water charcoal com-
bined with a reduced oxide of manganese prepared as herein-after described.
The well known purifying action of charcoal (animal and vegetable) which in its
ordinary state is liable to certain difficulties and objections is in my Invention
supplemented and improved by heating it in covered crucibles with from five to
fifteen per cent. or more of powdered commercial black oxide of manganese (the
mineral pyrolusite) together with a very small quantity of some fixed oil, resin,
or fat.
Having ascertained that the simple admixture of the aforesaid manganese dioxide
with the charcoal without previous heating had no utility as a filtering medium,
and was even injurious by reason of the diminution of the porosity of the charcoal,
I devise the above method with the object of oxidizing the hydrogen and other
oxidizable impurities of the charcoal, and hence approximating it to pure carbon in
a state similar in efficacy to platinum black rather than in its ordinary less powerful
analogy to spongy platinum.
The heating is of course out of contact with air, and the temperature sufficiently
high to cause the reduction of the manganese dioxide at least to inanganous-man-
ganic oxide, which afterwards acts as a carrier of oxygen, and thereby much pro-
longs the purifying action of the medium.
Another method of obtaining charcoal in combination with manganous-manganic
oxide is to saturate charcoal with manganous chloride (or even manganese residues)
and afterwards subjecting it to a strong heat in closed crucibles.
The charcoal prepared in the above manner may be employed in the filtration of
water in layers with sand and other filtering material in the usual manner.
Having thus described the nature of my Invention, and the manner of performing
the same, I would have it understood that I claim the use in the construction of
filters for purifying water of charcoal combined with a reduced oxide of manganese,
prepared substantially as herein described.
In witness whereof, I, the said Albert James Bernays, have hereunto set my
hand and seal, this Eleventh day of September, in the year of our Lord
One thousand eight hundred and seventy-eight.
RT J. BERNAYS. (L.S.)
ALDERIJ.