gh the filtering material to
the outside, the solids being retained inside, and are got rid of by
partially revolving the upper half to relieve it from the knuckle
joint, and, after being raised, the lower half is turned over by
machinery, and the solid matter is simply allowed to fall out into
wagons or trucks run underneath for that purpose. Such, in brief, is
the manner of using this filter press for chemical works' purposes.
The cost of each filter press, including royalties, is from L250 to
L300, the size being 8 ft. by 4 ft. diameter. Having a filtering area
of 100 square feet, it would require 32 of these applied to softening
water to effectually deal with 2,000,000 gallons per 24 hours; this,
at the lowest estimate for filters alone, would be L8,000, and, using
the same figures, L5,000 for lime mixing tanks, etc., as referred to
in the "Slack and Brownlow" purifier, would bring the total cost up to
L13,000, and the working expense would not be less than that required
to work the Porter-Clark process, and would probably be very much
greater. This filter press is not in use anywhere for dealing with
large quantities of water in connection with a town water supply.

A process which has been working for a long time at Southampton is the
Atkins system, which also includes the use of filter presses. The
pumping station and softening works are situated at Otterbourne, eight
miles from Southampton, and were built together as one scheme. The
mixing room has two slaking lime tanks, with agitators driven by steam
power. The mixture is then run as cream of lime into a tank 20 ft.
square and is then pumped into the lower ends of two lime water
producing cylinders. The agitation is here obtained by pressure from a
small cistern placed above them with a 12 ft. head, the pipe from
which is attached to the lower ends of the cylinders. This has been
found by experiment to be the most satisfactory means of obtaining the
proper degree of agitation necessary; the clear lime water is then
drawn off at the top of the cylinders, and flows by gravity into a
mixer, where it comes in contact with the hard water. Both flow
together into a distributing trough, from which it overflows into a
small softening reservoir, having a capacity of one hour's supply, a
weir being placed along the lower end, over which the water flows to
13 filter presses. The clear water from the filters is then conveyed
to a small well, from which the permanent engin