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SOME MEANS OF PURIFYING WATER.

There are several methods extant for the purpose of purifying and
softening water, and in the following brief account some of the chief
features of these methods are summarized. The Slack and Brownlow
apparatus we will deal with first. This purifier is one which is
intended to remove the matter in suspension in the water to be treated
by subsidence and not by filtration. The apparatus consists of a
vertical iron tank or cylinder, inside which are a series of plates
arranged in a spiral direction around a fixed center, and sloping at
an angle of 45 deg. on both sides outward. The water to be dealt with
flows through a large inlet tube fixed to the bottom of the cylinder,
rises to the top by passing spirally round the whole circumference,
and depositing on the plates or shelves all solids and impurities at
the outer edges of the plates. Mud cocks are placed to remove the
solids deposited during the flow of the water upward to the outlet
pipe, placed close to the top of the cylinder. One of these tanks, a
square one, is at work purifying the Medlock water at Manchester, and
on drawing samples of water from nearly every plate, that from the
lower mud cock showed considerable deposit, which decreased in bulk
until the top mud cock was reached, when the water was quite free from
deposit. It is stated that one man would be sufficient to attend to 20
of these purifiers.

To filter or purify 2,000,000 gallons per 24 hours would require 40
tanks, 10 ft. by 7 ft. diameter, each doing 2,000 gallons per hour,
and would cost, with their fittings, L6,400, including all patent
rights, but exclusive of lime mixing tanks, agitators, lime water and
softening tanks, engine and boiler, and suitable buildings, the cost
of which would not be far short of L5,000, or a total of L11,400 to
soften 2,000,000 gallons per 24 hours. The labor and other working
expenses in connection with this plant would not be less than that
necessary to work the Porter-Clark process, which is given as O.55d.
per 1,000 gallons.

The Brock and Minton filter press system is another method. This
patent press is made of steel, perforated with 1/2 inch holes. On the
inside of the shell there is first laid a layer of fine wire netting,
then a layer of cloth, and lastly another layer of wire netting of a
larger mesh than the other. The matter treated is pumped into the body
of the cylinder, the liquid passing throu