The Providence news. (Providence [R.I.]) 1891-1906, 1896-02-18
the run .from a regular stop at the rate Of

the run. from a regular stop at the rate OF
a drop a second.
The effect OF the presence OF this layer
was TO reduce the head or pressure .2S OF
q foot for us, 900, 600 gallons per acre.
The depth Of the water above the bed at
the commencement OF the run was nine
inches; the average length OF the run was
about eighteen hours.
Under these conditions Il was de-
termined how long after the commence
ment 81 the run the fltcring ability was
at a maximum and also the capacity OF
the altering, media to remove organisms
and also the possibility OF removing
organisms foreign TO river water and sim
ulating ~pathogenic bacteria in their life
history. In this last experiment the
Cruikshank bacillus and bacillus prodi-
giosus were used, since from their pathe-
genie properties they could be readily
distinguished from the water bacteria.
During the application OF the cultures
of bacillus prodigiosus In large quanti-
ties suspended in the nutrient media, the
numbers OF the common water bacteria
materially increased In the efiuent, the
PARTICLES OF quartz becoming covered
with a shiny, brownish deposit. Unsnc-
cessful efforts were made to cleanse the
quartz of this growth by steaming N
boiling the quartz for an hour. Finally, on
the application of a solution of n pint
of caustic soda to "A parts of water and
steaming, the normal white color OF the
quartz returned. The efficiency OF the
filter was raised by this process Of cleans
ing from 92.s per cent. to 95.6 per cent.
AS TO THE DANGERS
attending the use of alum in the applied
water and which Is held up as a warning
by the opponents OF mechanical filtra-
tion, this much may be said in reference
TO this series OF experiments:
While IL was necessary to add hall a
grain OF sulphate of alumina per gallon of
water filtered In order to obtain the most
satisfactory results, yet upon comparison
by the most careful chemical tests of the
water applied to the filter and that of
the efiuent, there was found TO be less
alum in the filtered water than in the
river water itself.
Inquiry from numerous manufacturers
using alum as precipitant in various
quantities In excess Of the amount used
In the experiments, revealed in nc in
stance any incrustation or scaling in the
boilers where such filtered water mad been
used. Communications with the various
boiler insurance companies ELECTED no re-
port OF scaling where such water was
used. There Is no recorded instance
where alum-treated water as a drinking
water has produced any ill-effects upon the
consumers.
This work was lone by order of the City
Council of the city of Providence, n
under the direction of q commission con-
sisting of superintendent of health, the
city engineer and the commissioner of
public works. The immediate super
vision of the operation was under the
supervision of DIR. G. V. Chaplin, the SUI
perintendent of health and a mem Der Of
this association, while the application Of
the various tests was made under the d.
rection of Mr.. Edmund b. Weston, &. e.,
from whose compilations aud reports these
abstracts have been taken. Most of the
bacteriologic work was done by the writer.
inasmuch as the writer, as well as
every person connected with the expert
ments, commenced the investigation
with the hrm belief that successful me-
cbanical filtration was not possible from
a bacteriologic view, it must be stated
now, after examination OF these figures,
that mechanical filtration under these
conditions can be firmly endorsed.