The evening times., 1896-02-22
President of lehigh University
Says Filtration Is Necessary.
FACTS TO PROVE HIS WORDS
Dangers OF Drinking the Liquid In It's
Natural State-The Kind, Cost and
Use Of Filter Needed for Large
Cities-Scientific Argument and
Analysis.

oi LeHiEn University, at Franklin Institute,
Philadelphia, last night, and it will be
interesting TO the thousands in Washington
who want pure drinking water.
After describing briefly the methods OF
collecting. storing and distributing sur
face and ground water, DIR. Drown turned
to the sanitary aspect of the water ques-
ti0n, and said:
I'VE do know some things about water
and Its relation TO disease. which have been
proved and which are no longer a matter OF
speculation or theory. One fact beyond
question Is that IL is unhealthy to drink
water which has received human excre-
ment. Many may be the diseases caused
by drinking such water, bat we know GER
tainly of twO-chOlera and typhoid fever.
Cholera fortunately. comes to us rarely.
but typhoid feyerais epidemic in our cities
using sewage-pollutetl water. and its exist
ence under these conditions is a disgrace
to our civilization. The cities having the
highest typhoid death-rate In this country
are those whose public water supplies con-
sist OF river or lake water directly contain
mated with sewage.
From the Cniied States census of 1890
we find that Allegheny heads the list with
nearly l 8 deaths per 10 900 living. Pittsburg
has nearly 13. Philadelphia and Chicago be-
tween 7andB- II I'VE compare with these fig
ures those of cities where the water shed of
the supply Is well protected from pollution
we find a marked difference. Boston. for
instance. has a typhoid death rate Thy the
same census) OF less than 4. New York and
brooklyn little over 2, and New Orleans,
which depends mainly ON rain water FOR
drinking, less than 2.
Compare again with these figures the
death rate of some European ci,ies-Glas-
gov. with the pure water OF Loeb Katrine.
has only 2 per 10000; Dresden and Vienna,
using ground water. less than l. or still
greater Significance, however, is u compari-
son with cities dependent for their water
supply on polluted streams, which are
filtered through sand before the water
is delivered 10 the consumer. Berlin. using
the filtered walsr OF the Hayel and Spree,
has a death .rate OF O.9; Breslau, filtered
filtered Oder water. IL. and London,
using mainly ;he filtered water OF the
Thames and Lra, only II.
WHAT rFILTRATION WILL DO.
This certainly seems conclusive as TO
actual disease-causing properties of sewage
lreHu'h ""tfis anu siiso tts ppssipuily vi
purifying sich water and making ii fit for
use by Mutation.
'.And YET, IN spite OF this proof of the eff
cheney of saaIsfiltrath,n In removing the
germs of tEpheid, cities like Philadelphia.
Chicago, AR~hy .Pittsbury. Allegheny and
many other ,sc-ntinue To drink sewage in
their water, and thus wiIifully sacrifice
scores Of lises every year.
"Thc7sai.f tIltEittea-ef water is not new
thing t,at is on trial. II has been used in
England andSJ SJGerfnany for fifty years and
more. The ,prdccss has been scientifically
studied, andihcre isa large Eteraturc on the
subject from engineering, chemical, biologi-
cal ard hygienic stardpoints.
Not only are polluted supplies regularly
filtered, but good surtlcc waters from COM
paratively minfa,,itcd watersheds are also
filtered, to take away minute organisms,
that tie water may bc delivered 10 the con-
sumner in n clear and attractive form.
intle over n year ago | visited the immense
new reservoir formed by danIming the
Vyrnwy Valley. in Wales. to form an addi-
tionai supply for Liverpool. This water is
collected from watershed in the Welsh
Mountains, almus: entirely free of pollu-
ton. Yet this water is regularly filtered
through saGdfbefore it is delivered to the cit
iZcns of Liverpool.
The Lawrence filter is two and a half
acres in extent, with a depth OF fine sard
OF from three to five feet. 1t took seven or
eight months to build. and cost about $685.
600, and the cost OF operating was in 1894
about $4,000. Its rate OF filtration is from
2.OO0.0O0 to 100000 gallons per acre
daily.
I'm general it may bc said that we should
calculate an acre of ritter surface for each
2.o0O.U00 gallons of water filtered daily.
This will allow of a rate OF 2,5OO.OU0 as
the actual rate. while pa rt of the filter
ing surface. which gradually becomes clog
ged. is being scraped. But this is 4 mimi
mum rate. 1t is no. inip robabie, from Law
renee experiments. that rate OF 900 900
or 4,G0O.uo0 gallons per acre could be
safely maintained. The rate OF filtration
after scrapiDg is generally lowered during
the first twent y-four hours, wben the maxi
mum rate can be resumed.
WORKING OF THE FILTER
The elementary idea of filter is a
porous medium in which the pores are
smaller than the substance to be removed.
Such filters We have in some natural sand
stones and in ung lazed porcelain But
filters of this character would he too slow
in their action for city's supply, al
though they do very well for household
use.
Now, the object of filtering u water
which tias been polluted by sewage is 10
remove the bacteria or germs of disease,
and these are infinitely small compared
with the spaces In an ordinary sand filter.
How is II, then, that filter can remove
them: When q filter has been In use for
some time we find it is more efficient
in removing bacteria than when the sand is
new and clean.
when The water which goes on to the
filter contains, say many thousand bacte-
ria TO the cubic centifneter, the effluent
water often CONTAINS none. So the fact
s that they. are removed. Now il we ex-
anime the sand we find that in the first
quarter OF an inch the bacteria are pres
INT by the million, and that the number
rapidly decreases as we GO downwards,
and that at the depth of u fooot there are
very few. :,
"Thc work Of the filter is mainly done
N the upper, three or four inches. Here the
bacteria are intercepted. partly by the
Inc layer Of vegetable matter with which
hc surface Of the filter becomes coated, and |
,y the Shiny surfaces OF the sand grains. |
)f course, In time, many of the bacteria |
lie in an unfavorable environment but |
he fact that VIC are most interested in |
germs it must necessarily in time foul the |
water which passes through 1t.
"Now It is a well known fact that an old |
liter is more, ,efficaeious than a new one. |
Ind it has also been repeatedly shown that |
urfacc water containing air in solution |
,oea NOT l,acOmp contnrnjpafe<1 in nassipv