The Providence news. (Providence [R.I.]) 1891-1906, 1896-01-29

steel filter cylinders filed with sand and
treated with sulphate Of alumina which
is the same as alum without the ammonia.
The sulphate OF alumina added to the
carbonate OF lime which is in the water
makes a suiphate Of lime plus hydrate Of
alumina which does the business form
ing a thin crust at the top. the hydrate
extracting all c~oloring matter IAN advan-
tage over the natural plant) and arresting
the bacteria. To clean the filters they
are reversed like any water filters, or the
water forced through the opposite end.
The percentage of bacter a arrested Is but
slightly increased in the mechanical
system, tho results being 9S in the ma
tural and 90 per cent. in the other.
In Europe the natural plan is generally
adopted; in this country, particularly in
the southern cities, where the water is apt
to be turbid, the mechanical plant is en-
ployed with greater or less success. In
Atlanta, especially, there is a fine plant.
The natural plant is used in two cities in
America and the only place where 1t is
successful is In Lawrence, Mass. Speaking
of the need OF covering the plants, Dr.
Chaplin quotes a Mr.. Eazen, who is said
to know more about such matters than
ANYBODY else in this country, as saying
that filtration plants should le housed
when the average mean temperature
falls below the freezing point. Here in
January the average mean Is ~ degree.
In Berlin, where the natural filtration is
used, the mean Is 81 degrees and expert
ence showed that it is nc bic to cover
the filter BEDS, for they cannot be cleaned
when covered with foot of ice. The sand
pened in a suburb of Hamburg once and a
typhoid epidemic resulted. There had
been a cold spell, followed by a thaw,
and the work of cleaning beds was begun.
II cleared of cold again, the SAND froze as
well as the water which they flowed over
it. When it thawed IL thawed in
spots. and holes anG cracks were made
in the beds through which the bacteria
ran and the sickness resulted. The city
engineer thinks the filter beds could be
made large enough aud the tiltering
process SO slow as to obviate the
danger, warm spells coming fire.
quently enough to permit clean
ing. The doctor thinks there Is aways
a danger and a chance however. The
plan OF mechanical filtration which it was
intended to adopt in 1894 embodied a
pretty su bstantial plant Of 60 steel tanks,
each IL feet in diameter, housed in a
pretty nice building. DIR. Chaplin says
that the principal objection to the city
adopting the mechanical system is the
liability of lawsuits accruing. 1t seems
that when it was decided to let the Morri-
son-Jewell people contruct a plant the
New York Filter Company enjoined
them because they claimed certain patent
rights and as the contract was not signed
the matter was dropped. There are
several different concerns in the mechani-
cal filter business and they are expanding
about all their substance in lawsuits,
consequently the doctor thinks that
Providence will never take the chances,s so
the way is clear for natural filtration.
DIR. Chaplin would, II he could, go ahead
and build a mechanical plant, and a better
one could be built than Is now on the
market, and take the chances with the
lawsuits. The city is constituted different
State and city boards of health are in
favor of mechanical filtration. DIR. Chaplin
says that the only proper location for a
natural plant is on the fats opposite the
pumping station at Pettaconsett. In
this he agrees with City Engineer Shed d.
The resolution which was tabled in
August, 1894, follows:
Resolved, That tho commissioners of public
work DO and he is hereby directed TO build.
by contract or other wise, a suitable system
OF gravity tltors In connection with the con-
struction Of the Providence water works, cap.
able Of Offering 10, 600, 600 gallons per day, in
accordance with plans and specifications OF the
city engineer, and to expend therefor not to
exceed the sum OF s2iO. 600, and the city treas
urer, acting unuer tho advice and direction
OF the Joint standing committee on finance, is
hereby authorized to hire the SEINE; and reso-
luton numbered io2. approved March 8, 1893.
and 81. approved June 8, 1904, and 39s, approved
July 8, 1894, are hereby rescinded, excepting.
however, so much Of said resolution iO2 as MP.
propristed $50. 900, and was modified ana In
corporated In resolution No. AS, passed July
r., 1893.
The resolution rescinded provided for
mechanical filters.
The estimated cost Of cleaning the
natural filter beds Is put at $500 per acre,
and Mr.. Shedd figures 1t out that that is
less than one-third of the estimated cost
of chemicals alone for the mechanical
plant.
A DEni' MYSTERY