The Providence news. (Providence [R.I.]) 1891-1906, 1896-02-20

Lime. ..'.. ...... '.'...'.'''.'..... W 1ooo
Sulphur trioxide. ...."............ 03129
include the above analysis, as there
are some people who seem to dislike the
idea of using basic sulphate of alumina
in connection with the publication OF
water. Basic sulphate of alumina is the
mmercial product which Is sold in the
market, and the first OF the bove analyses
shows that In reelity, the actual quantity
of alumina contained in the basic sulphate
of alumina, analysed Is less than Is per
cent. The quantity Of basic sulphate of
alumina used per gallon of water filtered,
during the experiments that were con-
ducted under my direction, was, as have
before mentioned, 6-10 of a grain. The
actual quantity Of alumina in the 6-10 of
grain, however, was but o. 0947 of a
grain, and the diameter of solid ball of
alumina weighing 0.0947 of grain is
only about ffty-seven thousandths of an
inch.
ses that the sample of PawtuXet river
water contained about SO per cent. as
much alumina per gallon as the sample Of
basic sulphate of alumina, and that the
sample OF Pawtuxet river water contained
per gallon, about 20 per cent. more
sulphur trioxide than the sample OF basic
sulphate OF alumina.
during the experiment, conducted un-
der my directions, great care was taken
to ascertain IL any of the alumina, that
was put into the water before il was fit
cred, could be found in the water after IL
had been filtered, and IL was demonstrat-
ed that there did not any of the alumina
in its original state pass through the fill
ter.
A very strong point in favor OF me-
chanical filtration was brought out dur
ing the experiments above mentioned,
namely: that of being able to thor
oughly cleanss the interior OF the filter
and the filter bed. Thus, for example, II
il should be found that the litter beds OF
a mechanical filter plant, after a run OF
six or eight months, more or less, should
contain large quantities OF bacteria,
which were supposed TO be propagating
i'm the same, there would be very little
need OF. theorizing in regard 10 them, as
tho filters could be thoroughly cleansed
| in very short time at a very slight ex-
pcnse, with soda ash and..steam.
Experiments that | have made i'm this
direction have shown that mechanical fl
ter beds Of crushed quartz, which, before
cleansing, were more OF less covered with
bacteria producing matter, and of n dark
brown color, could be bleached by the
process OF cleansing that | have Just
mentioned, TO a degree OF whiteness
which was only little less than what il
| was before Ii was put into the filter.
As mechanical fltration can be success
! fully accomplished at an average rate Of
filtration of 12s, ,O000Oo gallons per acre
rer "a hours, a mechanical filter plant
could be located upon very much small
| ler area OF land than would be required
by a natural hitter plant, through which
| the average rate OF tiltration was TO be
about 20O0,000 gallons per acre per "a
| hours.
| There need not be any apprehension in
regard TO the working OF a properly con-
structed mechanical filter plant IN winter,
as steam pipes would be arranged TO keep
the temperature of the buildings In which
the filters would be located above the
freezing point.
In closing would say, that experience
has taught me that careful preliminary
| Investigation in regard to engineering
problems OF moment are very rarely re-
| GREETED. Very truly yours,
EDMUND Is. WESTON, Z. Il,