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'
12-
AQUJIOUS
B:IVBUQJI&
.~
,
sold at
high
prices~
and
it
posaesses
tbe
greM.
recommendation of
being
readily
cleaned.
V
ariovs ehem.ical substances are
occasionally
added
to
water for
the
purpose
of
freeing
it
from
eome
of
it.a
impurities. Alum
is
often
used
to
purify thick mu<ldy water ;
if
employed at
all,
not more than
ten grains should
be
ad<led
to
every gallon ; one ingredient of the alum (the
Alumina), unites
with
the mechanical impurities
and falls with them to the bottom, whilst
an–
other portion
remains dissolved, and
considera–
bl
y
increases the hardness of the water ; the plan
is much inferior
to filtration.
A small
portion
of alkaline carbonates, such as carbonate of
soda
or
potash,
decomposes
the
earthy
salts,
and
pre–
cipita.t.es
them
in
an
insoluble form : they
form
a.
useful addition
to
very hard water when em–
ployed for internal
use, butah ould
not
be
iJi
·sufficient q_uantity
to
impart the · slightest soapy
taste.
Boiling
&as
a considerable
purifying
ef–
fect on water,
it
destroys
the
life
of
my
minute
a.nima.ls
or vegetables existing
in
it,
and
throws
downs. very considerable part
(but
not
the
whole)
of
the earthy matters in the form
of
fur or
rock. Persons
BO
unfortunately sitn&ted as
°°'
to be
enabled
to
obtain
any
other
water but such
as is much contamina.ted
with
decaying
matt.er,
and other impurities;
a.re
advised first
to
boil
a.nd
then to filter it
in
the manner recommended.
[N.B. Cochituate, Croton, and Schuylkill pure
waters require only the common filter sold a\
T;>lumbers' and hardware shops ; but the filter here
described
ia
needed for river and rain water.]