NOTTER ON THE EXAMINATION OF POTABLE WATER.
April, 1883.]
ORIGINAL COMMUNICATIONS. NOTE ON THE EXAMINATION OF POTABLE
WATER, By
WITH EXPERIMENTS.
J.
they are only of recent date, and have not been subjected to the test of time, I venture to place on
To
ing
use
and
the
Unfortunately making a chemical and I am obliged,
means at
nitrate. an
my
almost
shown The
me
be
to
a
form
crystallised
should,
if
possible,
The action of silver nitrate
experiment glass. glass, take 160
which
by
we can
sample. rarely
I have
same
manner;
bined with
"
found this test fail, and if two
one or
others, it gives
a
com-
very fair
indication of the chemical characters of
a
water.
test, which
There is another
never qualitative be omitted. A little practice will always us to form a rough estimate of the
nitrites present. It is of the contamination which
true
caustic de-
c.c's of pure dis-
glass containing the of as a sort pilot," or otherwise the purity judge
has be
performed
ammonia
amount of nitrates and
used, but I have had tolerably fair results with the ordinary lunar caustic.
best
is
the
solution of silver nitrate.
of silver
saturated solution
exposure. The second distilled water will act
enable
qualitative test, and certainly simplest, long experience in water analyses
drops
nitric acid
of dilute
expose both to the direct rays of the sun and note the amount of blackening and the time of
is concerned. The best
a
examined,
to be
water
and treat in the
water
should
are
The
In another
nil, in instituting a comparison, to have recourse to the simplest qualitative tests as far as the chemical examination of the samples examination
few
a
ordinary
tilled
for
disposal
it is
the follow-
generally adopt
c.c's of the
100
5 c.c's of
of the
record.
this test, I
add to it
in
which
matter, upon
method.
Take
Lane
Notter, A rmy Medical Department. In a former paper I pointed out the absolute necessity there is for always supplimenting the chemical analyses of potable waters by a careful microscopic examination of the sediment, and never allowing our judgment to rest on the data supplied by chemical tests alone. I have lately undertaken a series of experiments with a result so favourable, that although
four
presence of organic capable of acting.
85
they
tell
only
is past, but they also give us a clue to the probable nature of the organic matter present. Nitrates indicate that process of natural
always
water
a
has
purification,
to assert
undergone
and
it
a
is not
with confidence that such
facility
with which it parts with its oxygen, the silver being reduced to its metallic state, and the oxygen combining with the
easy process will be uniform or lasting. The simplest qualitative test for nitrates is a solution of brucine added
elements of the
organic
and
pends
upon the
as a
matter.
This effect is very much promoted by expoto sunlight or diffused daylight. Pure
sure
silver nitrate is bat if organic
not
changed by
exposure to light, matter be present, a black deposit,
silver, is produced. almost meet with a sample
divided
containing finely Again, we never of water without
chlorides, and if these
are
pre-
sent, on the addition of the silver nitrate solution a silver chloride will be formed, brilliantly white
first, but soon becoming violet and eventually black, if exposed to daylight, the silver chloride, at
being reduced to a sub-chloride (Ag? Cl.\ blackening takes place much more rapidly
a
a
few
to a
drops
quantity of the sulphuric acid let
small
of pure
the side of the test tube. If nitrates a
beautiful
the
pink sulphuric
zone
will
acid.
down
are
present, the top of
on
appear With these
water,
qualitative
tests added to the information derived from
physical characters, opinion
of the
we can
water.
form
a
the
fairly good
Of course,
if other
disposal, we should not be in limiting our examination to a few justified qualitative tests only. means are
at
our
The next method of examination is I want
The
been
in the
cent
one
that
It has
particularly to draw attention to. suggested by Dr. Angus Smith in a repaper, and may be shortly described as a
THE INDIAN MEDICAL GAZETTE.
86
process for
developing
The results
so
far
the
are
living
such
as
germs in water. to justify the
belief that this method will form
good
test for
states that
heated in to
potable when 2^ per cent,
of
Smith
gelatine
well
forms
a
transparent
which is not movable like the water itself.
When soluble matter
develops
matter of the water and
the solid the
extremely-
little water is mixed with the water
a
be tested, the mixture
mass
an
Dr. A.
waters.
insoluble
or
bottom, sphere
the
organic
makes itself visible in
form,
it does not fall to
but each active
shows around
it the
observed.
from
point activity, and that sphere is gelatine preserves the whole
of its
The
A.
[April, 1883.
Bacteria active round the
present both in the free and none excursive. B.
No
C.
Bacteria
spheres formed,
the matrix
beginning are
had
to detach themselves from it.
present both in their primary
form and
also free.
bacterium termo is D.
There
are
easily recognised. or two spheres exhibit hardly any
few bacteria which
wood which had
cotton
immediately
before
subjected high temperature for somethen exposed with their flasks were The time.
been
to
contents to
a
sunlight.
elapsed these preparations 48 were each carefully examined by the microscope. The power employed was J^th inch. A. Bacteria in one or two of the spheres, but movement sluggish, and exhibiting extremely little activity. After
hours had
No evidence whatever of any forms. C. A large number of spheres forming ; bacteria very plentiful, active and free in a few B.
instances. D.
change as yet apparent. preparations were allowed to hours longer and again examined. 48
The main
No
same
re-
a
move-
ment.
On further examination after the the same results
favouring the growth organic life, is a great filtering medium."
closed with clean
with
one
the mouths of the flasks
were
They zooglsea shape of
or
The dumb-bell
days, nearly
and
forms.
very active, they appear as if broken down, and they are
keeps a record for a time both of the intensity of life in the liquid. quality Following out the plan recommended, I obtained four samples of water, one taken from from a one an ordinary charcoal filter (A), spongy iron filter {B), one from a surface well in the native bazaar (C), and one from a tolerably clean well in the cantonment (Dj. The qualitative tests of A, B, and D, were very good, as were the physical characters. C The was yellow in colour and slightly turbid. qualitative examination was unsatisfactory. 100 c.c's of each sample of water were put into a clean flask and 2^/2. c.c's of gelatine added, this having previously been dissolved and well heated; action and
no
spheres, and zooglsea form,
in the C. there
was a
were
lapse
of
io
obtained, only
large increase in the number
of bacteria, and had
spirillum was also found, torulai developed and mycelia of fungi were
abundant. This series of experiments bears out the views
expressed by the
River Pollution Commissioners
sixth report, that filtration through charcoal favours the development of lower organin their
At page 220 they state as follows found that myriads of minute we deed, were developed in animal charcoal and isms.
out with the water when these filters
for Thames water"?and
animal charcoal
"
"
:
In-
worms
passed
were
used
the property which a high degree of
possesses in
of the lower forms drawback to its
use
of
as a
The results obtained appear so far satisfactory a as to lend hope that further investigation will throw
more
light
on
this
complex subject. i6tk, 1883.
Meerut, N.-W. P., February
April, 1883.]
ORIGINAL COMMUNICATIONS. NOTE ON THE EXAMINATION OF POTABLE
WATER, By
WITH EXPERIMENTS.
J.
they are only of recent date, and have not been subjected to the test of time, I venture to place on
To
ing
use
and
the
Unfortunately making a chemical and I am obliged,
means at
nitrate. an
my
almost
shown The
me
be
to
a
form
crystallised
should,
if
possible,
The action of silver nitrate
experiment glass. glass, take 160
which
by
we can
sample. rarely
I have
same
manner;
bined with
"
found this test fail, and if two
one or
others, it gives
a
com-
very fair
indication of the chemical characters of
a
water.
test, which
There is another
never qualitative be omitted. A little practice will always us to form a rough estimate of the
nitrites present. It is of the contamination which
true
caustic de-
c.c's of pure dis-
glass containing the of as a sort pilot," or otherwise the purity judge
has be
performed
ammonia
amount of nitrates and
used, but I have had tolerably fair results with the ordinary lunar caustic.
best
is
the
solution of silver nitrate.
of silver
saturated solution
exposure. The second distilled water will act
enable
qualitative test, and certainly simplest, long experience in water analyses
drops
nitric acid
of dilute
expose both to the direct rays of the sun and note the amount of blackening and the time of
is concerned. The best
a
examined,
to be
water
and treat in the
water
should
are
The
In another
nil, in instituting a comparison, to have recourse to the simplest qualitative tests as far as the chemical examination of the samples examination
few
a
ordinary
tilled
for
disposal
it is
the follow-
generally adopt
c.c's of the
100
5 c.c's of
of the
record.
this test, I
add to it
in
which
matter, upon
method.
Take
Lane
Notter, A rmy Medical Department. In a former paper I pointed out the absolute necessity there is for always supplimenting the chemical analyses of potable waters by a careful microscopic examination of the sediment, and never allowing our judgment to rest on the data supplied by chemical tests alone. I have lately undertaken a series of experiments with a result so favourable, that although
four
presence of organic capable of acting.
85
they
tell
only
is past, but they also give us a clue to the probable nature of the organic matter present. Nitrates indicate that process of natural
always
water
a
has
purification,
to assert
undergone
and
it
a
is not
with confidence that such
facility
with which it parts with its oxygen, the silver being reduced to its metallic state, and the oxygen combining with the
easy process will be uniform or lasting. The simplest qualitative test for nitrates is a solution of brucine added
elements of the
organic
and
pends
upon the
as a
matter.
This effect is very much promoted by expoto sunlight or diffused daylight. Pure
sure
silver nitrate is bat if organic
not
changed by
exposure to light, matter be present, a black deposit,
silver, is produced. almost meet with a sample
divided
containing finely Again, we never of water without
chlorides, and if these
are
pre-
sent, on the addition of the silver nitrate solution a silver chloride will be formed, brilliantly white
first, but soon becoming violet and eventually black, if exposed to daylight, the silver chloride, at
being reduced to a sub-chloride (Ag? Cl.\ blackening takes place much more rapidly
a
a
few
to a
drops
quantity of the sulphuric acid let
small
of pure
the side of the test tube. If nitrates a
beautiful
the
pink sulphuric
zone
will
acid.
down
are
present, the top of
on
appear With these
water,
qualitative
tests added to the information derived from
physical characters, opinion
of the
we can
water.
form
a
the
fairly good
Of course,
if other
disposal, we should not be in limiting our examination to a few justified qualitative tests only. means are
at
our
The next method of examination is I want
The
been
in the
cent
one
that
It has
particularly to draw attention to. suggested by Dr. Angus Smith in a repaper, and may be shortly described as a
THE INDIAN MEDICAL GAZETTE.
86
process for
developing
The results
so
far
the
are
living
such
as
germs in water. to justify the
belief that this method will form
good
test for
states that
heated in to
potable when 2^ per cent,
of
Smith
gelatine
well
forms
a
transparent
which is not movable like the water itself.
When soluble matter
develops
matter of the water and
the solid the
extremely-
little water is mixed with the water
a
be tested, the mixture
mass
an
Dr. A.
waters.
insoluble
or
bottom, sphere
the
organic
makes itself visible in
form,
it does not fall to
but each active
shows around
it the
observed.
from
point activity, and that sphere is gelatine preserves the whole
of its
The
A.
[April, 1883.
Bacteria active round the
present both in the free and none excursive. B.
No
C.
Bacteria
spheres formed,
the matrix
beginning are
had
to detach themselves from it.
present both in their primary
form and
also free.
bacterium termo is D.
There
are
easily recognised. or two spheres exhibit hardly any
few bacteria which
wood which had
cotton
immediately
before
subjected high temperature for somethen exposed with their flasks were The time.
been
to
contents to
a
sunlight.
elapsed these preparations 48 were each carefully examined by the microscope. The power employed was J^th inch. A. Bacteria in one or two of the spheres, but movement sluggish, and exhibiting extremely little activity. After
hours had
No evidence whatever of any forms. C. A large number of spheres forming ; bacteria very plentiful, active and free in a few B.
instances. D.
change as yet apparent. preparations were allowed to hours longer and again examined. 48
The main
No
same
re-
a
move-
ment.
On further examination after the the same results
favouring the growth organic life, is a great filtering medium."
closed with clean
with
one
the mouths of the flasks
were
They zooglsea shape of
or
The dumb-bell
days, nearly
and
forms.
very active, they appear as if broken down, and they are
keeps a record for a time both of the intensity of life in the liquid. quality Following out the plan recommended, I obtained four samples of water, one taken from from a one an ordinary charcoal filter (A), spongy iron filter {B), one from a surface well in the native bazaar (C), and one from a tolerably clean well in the cantonment (Dj. The qualitative tests of A, B, and D, were very good, as were the physical characters. C The was yellow in colour and slightly turbid. qualitative examination was unsatisfactory. 100 c.c's of each sample of water were put into a clean flask and 2^/2. c.c's of gelatine added, this having previously been dissolved and well heated; action and
no
spheres, and zooglsea form,
in the C. there
was a
were
lapse
of
io
obtained, only
large increase in the number
of bacteria, and had
spirillum was also found, torulai developed and mycelia of fungi were
abundant. This series of experiments bears out the views
expressed by the
River Pollution Commissioners
sixth report, that filtration through charcoal favours the development of lower organin their
At page 220 they state as follows found that myriads of minute we deed, were developed in animal charcoal and isms.
out with the water when these filters
for Thames water"?and
animal charcoal
"
"
:
In-
worms
passed
were
used
the property which a high degree of
possesses in
of the lower forms drawback to its
use
of
as a
The results obtained appear so far satisfactory a as to lend hope that further investigation will throw
more
light
on
this
complex subject. i6tk, 1883.
Meerut, N.-W. P., February
