Evening capital. (Annapolis, Md.) 1884-1910, 1890-10-21

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rests the larger particles of suspended
matter on the surface. vile the smaller
ones are separated by the i rec Of adhe-
sion TO the sand and gravel On the dis
solved impurities filtration thu augh such
a medium has little action When first
used, certain quantity of air is present
within the pores and instertices Of the
sand and this has some slight effect, for
two or three days. in oxidizing a small
quantity of the dissolved organic mat
tiers 1t may be stat. as a rule that eve
~ filter win require close watching, Scon-
slant cleansing and frequent renewa. of
the filfering medium. DIR. Molten states
that spongy iron, which is metallic iron
reduced from common are without fusion
and is consequently in a porous and fine
ly divided condition. appears to be very
active agent in removing organic matter
from water and certainly reduces nitrates
and nitrites, conYerting part of their
nitrogen into ammonia. There are re-
ducing and oxidizing agencies constant
ly at work in the spongy iron filter and
the several oxides of iron are present in
their nascent state Altogether we may
consider spongy iron as the very best fil-
tering medium known. But while spon-
gy iron removes impurities of an organ
ic nature, it yields to water a certain
amount of iron which has to be got rid
of This was formally done by means
of layer of charcoal placed beneath the
spongy iron receptacle; but since the re-
port of the Rivers Pollution commission
of England pointed out that animal char
coal favored the growth of low organ
isms, it has been abandoned and Bischof
recommends what he calls prepared sand.
This is q mixture of very fine gravel
with native black oxide of manganese.
This answerf the purpose of removing
the excess of iron and has the further
supposed advantage of being of mineral
origin. The iiltering therefore, in this
case, is entirely carried out through ma
terials of inorganic origin.
In order to test the purifying power of
the spongy iron as filtering medium,
DR.. Molten instituted an interesting ser
les of experiments upon water which
contained so large an amount of organic
impurity as to condemn it absolutely for
dictetic purposes In concluding his
notes on spongy iron filters he says: We
may with safety state that this material
is capable of exercising a powerful eff
feet on dissolved organic matter in wa
Ter; that its action is extremely uniform
and satisfactory; that 1t is very durable
and that it is one of the best and safest
filtering media in the market. Without
| entering into a detailed consideration of
various household filters which have
been recommended and used, we may
notice a very simple apparatus recon-
mended by DR.. Parks; Get common
earthenware flower pot; cover the hole in
the bottom with bic of zinc gauze or
bit of clean washed flannel which should
be ckeRged from time to time; then get
seHe rather small gravel, wash it well
and put 1t into the pot to the heighth of
three inches; then get some white sand,
wa b it very clean and put that on the
gravel to the heigth of three inc he's; then
take two pounds of animal charcoal,
wash that also by putting it into an
earthen vessel and pouring boiling water
on it; then, when the charcoal has subsid
ed, pour of the water and pour some
more for three or four times. When the
animal charcoal has been thus washed,
put it on the sand and press itweu down.
Have four inches, in thickness of the
charcoal, if possible. The filter is now
ready Pour water into the pot and let
it run through the hole into large glass
bottle. After time the charcoal will
get clogged; take off little from the
top and boil st two or three times and
then spread it out and let 1t dry before
the fire. 1t will then be as good as ever
From time to time all the charcoal and
the sand also may want washing. By
filtering in this way and by boiling the
water, many dangers are averted That
filtration, properly performed, will cor
rect the bad odor and taste and purify
the water, / can vouch for, as | have tes-
ted it.