success. The results, when compared with those obtained by
the " albumenoid ammonia " process, prove that there is no
relation between the amount of ammonia yielded by a water
when distilled with an alkaline solution of permanganate of
potash, and the amount of oxygen absorbed when the same
water is digested with an acid solution of the same salt.
This process tells us little or nothing of the nature of the
polluting material; it does not even distinguish between
organic matter of vegetable and animal origin, and it affords
us no evidence of the amount of such substances present.
The presence of certain bodies of mineral origin (sulphuretted
hydrogen, nitrites, the lower oxides of iron, etc.) also absorb
oxygen, and unless great care is taken to ascertain the absence
of these, or to ascertain the exact amount of oxygen consumed
by them if present, serious errors may be introduced. When
these corrections are made the oxygen process is still open to
all the objections which have been urged against the albu-
menoid ammonia process. It may condemn a perfectly harm-
less water as polluted, and pass as of good quality a water of
most dangerous character. The following table was devised
by Drs. Tidy and Frankland.
Amount of Oxygen absorbed by 1,000,000 parts of Water.
Upland Surface
Water.
Water other than
Upland Surface
Water.
Water of great organic purity
„ medium purity
„ doubtful purity
Impure water
Not more than 1/0
3-0
4-0
More than 4*0
Not more than *5
„ 1-5
„ 2-0
More than 2*0
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174 WATER SUPPLIES
When the quality of a water is considered - from the bio-
logical side instead of the chemical, the absurdity of dividing
waters into classes of pure, medium, doubtful purity, and
impure, is obvious. A water containing a poisonous quantity
of typhoid bacilli might upon analysis be brought within
any of these classes, according to the quantity and quality of
the accompanying impurities. In the analyses given below
there are instances of waters coming within Tidy's limit of
" great organic purity," yet which proved to be capable of
causing disease. I have examined many such waters myself,
and have also passed many waters as perfectly safe for
domestic purposes which a mere reference to the above
standards would have condemned as doubtful or impure.
Many other special processes for determining whether a
water be safe or dangerous have been devised, but inasmuch
as they are rarely used, it may safely be inferred that they
possess no advantage over those to which we have already
referred.
Whilst no single determination will enable the analyst to
certify that a water is free from danger, or that it is so
polluted as to be dangerous to health, the determination of
several constituents may enable him to pronounce it to be
polluted and dangerous, but will never justify him in certify-
ing that it can be used absolutely without risk. As the
freedom from all dangerous polluting material is the informa-
tion usually sought from the analyst, it follows that if this
cannot be ascertained by analysis, a chemical examination is
in most cases quite useless. Where a water is known to be
contaminated with sewage, or known to be liable to such
pollution, an analysis is superfluous. When we also consider
that many sources of supply are only subject to intermittent
pollution, and that waters from the same reservoir or from
the same well (vide Analyses Nos. 24, 25, and 26, 27) may
vary considerably in composition, according to the depth from
which the samples are taken, the character of the season,
etc., it is obvious that the chemical examination of a water
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THE INTERPRETATION OF WATER ANALYSES 175
is a matter of comparatively trifling importance compared
with the thorough examination of its source and an accurate
knowledge of its history. Frequently waters are sent for
analysis, and the analyst is wilfully kept in ignorance of
their origin lest the information should prejudice his
report, yet without this knowledge he is not justified in
expressing an opinion whether any water can be used with
safety. In commenting upon a recent paper in which I
expressed these views, a writer in the Chemist and Druggist
says : "It would seem, therefore, that we are face to
face with the question, 'Is water analysis a failure.' It
has been so exclusively the province of chemical analysts
to pronounce judgment upon domestic waters, and they
generally have given so little attention to the large issues
attached to analysis, and so very much to sets of standard
figures for chlorine, nitrogen, hardness, and so on, that the
attack from the medical health side is not unexpected.
There has been more wrangling over water analyses than
over anything else in chemistry — and for what? Some
figure in the second or third place of decimals, probably, and
in regard to what this ammonia or that ammonia implies,
when a visit to the source of the water and an inspection of
the sewage trickling into it might settle everything. That
is what Sir George Buchanan and Dr. Thresh advocate."
The Royal Commission on Metropolitan Water Supply
received evidence proving that waters containing very large
amounts of organic matter were drunk continuously by a popula-
tion with perfect impunity, whilst other waters containing so
little organic matter as almost to defy chemical detection
had proved, time after time, to be of the most poisonous
character. For these reasons they conclude that the water
question has passed from the domain of chemistry into that
of biology. This, however, is not strictly correct. The
biological problems involved in the investigation of water
supplies are numerous and complex, and as yet but im-
perfectly understood. At the present time it is doubtful
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1 76 WA TER SUPPLIES
whether a biological examination really tells us more than a
chemical analysis, and very often it cannot tell us as much.
The reason will be explained shortly.
Although a mere analysis cannot guarantee us purity and
safety, yet it very frequently can reveal to us impurity and
risk. When the source of a water, upon most careful examin-
ation by an expert, is found to be free from all danger of
pollution, and the chemical examination proves that the in-
organic constituents are unobjectionable both in quantity
and quality, and that organic matter is absent or present in
barely appreciable amount, then safety, so far as human
foresight can be trusted, may be guaranteed. If organic
matter be present in appreciable quantity — that is, if the
water yield such a quantity of organic nitrogen and carbon,
or albumenoid ammonia, or requires such an amount of
permanganate for oxidation as to render it of suspicious or
of doubtful purity — a study of the history of the water and
of its geological source may, and generally does, enable an
opinion to be formed as to the nature of the organic matter,
and as to whether it is of an innocuous or dangerous charac-
ter. Chemical analysis, therefore, has its use; it is only
when it is made the sole arbiter between safety and risk
that it is abused, and is liable to lead to errors fraught with
most disastrous consequences. Let the analysis be as careful
and complete as possible, but let the results always be inter-
preted in the light afforded by a searching examination of
the source of the sample. Let all so-called standards be
abandoned as absurd, and let the opinion as to whether a
water is dangerous or safe be based upon a full consideration
of other and more important factors.
In the following table the erroneous conclusions which
may be deduced from a too great dependence upon analytical
data are fully exemplified.
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THE INTERPRETATION OF WATER ANALYSES 177
Remarks.
1. Analysis of water from the river Ouse below where it
receives the sewage of Buckingham. Examined for
the Town Council, 29th February 1888, by W. W.
Fisher, Public Analyst. Report — " Does not
appear from the analysis to contain sewage matters."
Quoted by Dr. Parsons in his report to Local
Government Board on an outbreak of enteric fever
in 1888, as a "further illustration of the inability
of a chemist to prove the quality of organic matter
in water when its quantity is small."
2. Analysis of the Buckingham public water supply by
Mr. Fisher. Certified by him to be a first-class
water, yet believed by Dr. Parsons to have been
the cause of the above outbreaks of the Mountain Ash water
supply (spring and surface water) by Dr. Dupre,
November 1887. A serious outbreak of typhoid
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THE INTERPRETATION OF WATER ANALYSES 183
fever occurred here, commencing in July 1887, and
continuing until October. Mr. John Spear investi-
gated it for the Local Government Board, and
attributed the epidemic to insuction of filth into
one of the water mains during intermission of the
service. Dr. Dupr6 found the samples almost
identical from a chemical point of view, and very
pure and free from any indication of sewage pollu-
tion. The two samples, however, which were token
from the taps, after six hours' intermission, were
found, when examined mteroscofricaHy, to contain
fungoid growths and large animalculse, which were
absent from the two other samples.
18-23 are analyses quoted from the Reports of the
Massachusetts State Board of Health, 1890-92.
18. A sample of unpolluted surface water containing less
nitrates and yielding more albumenoid ammonia
than (19) a sample of surface water known to be
polluted by sewage.
20. The average of a series of monthly examinations of
the water of the Merrimac River, supplying the
town of Lowell during 1891, when typhoid fever
was epidemic, and attributed to the water being
specifically infected nine miles above the intake.
21. Analysis of water from the Chicopee River, supplying
the city of Chicopee. Specific pollution is believed
to have taken place seven miles above the intake,
and to have caused an outbreak of typhoid fever in
the city.
22. Analysis of the water from No. 4 reservoir, the purest
of the four water supplies to the city of Boston,
and (23) of the water from Mystic Lake, the
most impure supply, showing that the albumenoid
ammonia yielded by the latter does not exceed that
yielded by the former.
24, 25 are waters from a deep well in Essex ; (24)
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184 WATER SUPPLIES
collected during dry weather; (25) collected eighteen
hours after very heavy rain. This well water is
liable to most serious pollution, yet a report based
merely upon the results of the first analysis would
most certainly have been favourable.
26, 27 are waters taken by me from the same well ; 26
from near the surface, and 27 from near the
bottom.
28, 29, 30. Analyses of waters from bored wells in the
chalk supplying the Suffolk County Asylum. From
a Report by Dr. Geo. Turner on an outbreak of
dysentery.
28, 29. These samples were taken from the same well
(350 feet deep), the first on 11th October 1893 and
the other ten days later. The difference in the
amount of chlorine is most marked, and led Dr.
Turner to conclude that the lining of the bore was
defective, admitting subsoil water. Sample 28
corresponds closely with No. 30, which was taken
from a second bored well, 305 feet deep, and only
16 feet from the first well. Waters 28 and 30 are
probably free from admixture with subsoil water.
That such water gained access to the well from
which Nos. 28 and 29 were taken was proved by
digging a hole near the bore and pouring into it a
quantity of solution of chloride of lithium. Two
days later, lithia could be detected in the water
pumped from the bore tube. No. 29 is an example
of an impure disease-producing water, containing
less chlorides and absorbing less oxygen than an
unpolluted water from the same source.
With the discovery of the fact that such diseases as typhoid
fever and cholera are due to the introduction into the system,
not of dead organic matter, but of actual living organisms,
faith in the chemical analysis of waters began to be shaken.
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THE INTERPRETATION OF WATER ANALYSES 185
When still more recently the actual microbes causing these
diseases had been identified, and processes had been devised
for isolating them from the multitude of other organisms
found in water, it seemed as though the examination of water
for sanitary purposes had passed from the domain of the
chemist to that of the bacteriologist. The study of the
number and character of the bacteria, it was hoped, would
enable the biologist to definitely pronounce whether a certain
water was capable of causing disease, or whether it was
perfectly harmless in character. Up to the present time such
hopes have not been realised, and the results of an ordinary
bacteriological examination are as likely to be misleading as
those of a chemical analysis. The reason for this is not
difficult to explain, when the significance of certain of the
discoveries made by bacteriologists is thoroughly understood.
An enormous number of species of bacteria have already been
discovered, although the science is in its infancy. They are
almost ubiquitous, abounding in the air, water, and nearly all
articles of food and drink. Of this immense variety very
few appear to be capable of causing disease ; the remainder
are perfectly harmless to human beings, whilst many are
already known to discharge most important functions in the
economy of nature. Upon their presence the fertility of soil
in a great measure depends; they break down the dead
organic matter into the simpler forms which can be assimi-
lated by the roots of plants. By their action the foul organic
constituents of polluted water are converted into carbonic and
nitric acid, which, in combination with the mineral bases, form
innocuous carbonates and nitrates. They are, in fact, nature's
scavengers, consuming the foul and effete, and producing there-
from matters of a harmless character.
The microbes found in water are chiefly bacilli Micrococci
are comparatively rare, whilst spirilla are not uncommon,
especially in polluted waters. Already over 200 distinct
species of microbe have been discovered in potable waters,
and amongst these are several which are pathogenic or disease
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186 WATER SUPPLIES
producing. According to Professor Percy Frankland, 1 these
Typhoid bacillus
Cholera spirillum, or " comma bacillus "
Tetanus bacillus
Anthrax , ,
Tubercle ,,
Bacillus brevis
, , capsulatus
„ proteus fluorescein
, , coli communis
,, hydrophilus fuscus
,, pyocyaneus
Staphylococcus pyogenes aureus, and the organisms causing
septicaemia in mice and rabbits.
Up to the present, however, the only diseases which are
certainly caused by drinking specifically-infected water, and
the micro-organisms of which have been with certainty
discovered in such waters, are cholera and typhoid fever.
Doubtless further research will add to this short list, but as
yet the organisms causing malaria, dysentery, and other
diseases, believed to be produced by specific microbes entering
the system with the drinking water, have not been with
certainty identified therein. The utmost, therefore, that can
be expected of the bacteriologist is that he should discover
and identify the cholera or typhoid bacillus, should either
of these organisms be present in a sample of water submitted
to him for examination. The multitude of other bacilli
present, however, renders this a difficult and often impossible
task ; the search has been likened to the finding of a needle
in a stack of hay. Whilst, therefore, the absolute identifica-
tion of the specific cause of cholera or typhoid fever
establishes its presence, the failure to isolate it is no proof
of its absence. As a matter of fact, numerous samples of
water, credited with the production of one or other of these
1 Journal of State Medicine, January 1894. "The Bacteriological
Examination of Water."
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THE INTERPRETATION OF WATER ANALYSES 187
diseases have been examined with negative results. As
examples may be quoted the examinations of the water
supplies to Hamburg and Altona during the cholera epidemic,
and the water supplies to Worthing, and to the towns in the
Tees valleys, during the outbreaks of typhoid fever, which
recently occurred there. Although the Elbe was known to
be polluted with cholera excreta, the comma bacillus was
never discovered in the imperfectly-filtered river water, to the
use of which Koch and others, who investigated the outbreaks,
attributed their occurrence. At the commencement of the
second serious epidemic of typhoid fever at Worthing, two
samples of the water were submitted to bacteriological exami-
nation by Professor Crookshank. He found that they contained
far fewer bacteria than the water supplied to King's College,
and that there was a marked absence of liquefying colonies.
" There was no colony of typhoid fever bacilli, and no bacillus
to which suspicion could be attached of producing typhoid
fever." He concluded, from the results of his bacteriological
examination, " that both samples of the Worthing water rank
as very pure water." Considering that during the construc-
tion of additional works in the spring, a fissure was opened
which discharged into the wells a large volume of water,
polluted by surface drainage, and leakage from defective
sewers, and that this mixture of well and surface water
thereafter was supplied to the town, and was the water
examined by Dr. Crookshank, it is not surprising that the
results of these and other examinations were considered by
the public as "most remarkable." Chemical examinations
made from time to time also failed to detect any pollution.
The following statements, made by the Deputy Mayor of
Worthing 1 at a meeting of the Town Council, held 18th July
1893, are particularly interesting, not only as showing how
little reliance can be placed upon either the bacteriological or
1 From Repoi tin the Sussex Coast Mercury, 22nd July 1893. Worthing
has a population of about 17,000, and during the year 1893 nearly 1500
cases of typhoid fever occurred.
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1 88 WATER SUPPLIES
chemical examination of drinking waters, but also as showing
the disastrous results which may follow misplaced confidence
in these results. The Deputy Mayor, at the above meeting,
after speaking of the finding, about two months ago, of the
fissure which gave to the town an enormous additional yield
of water, said : " We congratulated ourselves upon that fissure,
but I think there is no doubt, and certainly no member of
the Sanitary Committee has any doubt, that it is to that very
fissure the whole of the difficulty we are sustaining, and have
sustained, is entirely due." He then referred to the various
chemical and bacteriological analyses which had been made,
resulting in the water being pronounced thoroughly good and
pure. Notwithstanding these results the Committee cautioned
the public that they should boil the water, and the boiling
went on until the first outbreak practically ceased. "We
were hoping," he said, " that the difficulty had ceased, and
that we were to have no more typhoid among us; but,
unfortunately, another analysis was made by Dr. Crookshank,
the water being taken from two or three different sources,
and each sample was declared to be good. Perfectly pure
were, I think, the doctor's words. Well now, to that, I am
afraid, to some extent, we may attribute the cause of the
second outbreak. It was stated publicly, with the best
intentions, to allay public excitement and the panic which
was prevailing, that the water was perfectly pure, because we
had the best evidence that it was so ; and I have no doubt
that the public, who do not like the trouble of boiling every
drop of water they drink, ceased the boiling, and thus the
second outbreak came upon us, and is still going on." It is
quite unnecessary to point the moral of this plain statement
of facts. As it has been found impossible to dam out the
water from the prolific but fatal fissure, the present source
of supply is being abandoned. A proposal to attempt the
purification of the water by filtration through sand has not
been acted upon, Dr. Thorne having brought under the notice
of the Sanitary Authority Professor Koch's experience, to
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THE INTERPRETATION OF WATER ANALYSES 189
the effect that, " even under favourable circumstances, sand
filtration cannot give absolute protection against the danger of
infection." During the Tees valley epidemic, also, the water
was repeatedly examined bacteriologically. Although an
excessive number of micro-organisms was found, sufficient in
fact to qualify the opinion that the water was polluted, the
typhoid bacillus was not once discovered.
It has recently been asserted that the so-called typhoid
bacillus (Eberth's) is often absent from typhoid stools, and
that the bacillus coli communis, which is invariably found in
all stools, is capable under certain conditions (probably by
growth in cesspools and sewers) of acquiring pathogenic
properties in man. It is even, by many, believed that this is
either a degenerate form of Eberth's bacillus, or that it is
capable of taking on the same properties, and of causing the
same disease — typhoid fever. Such being the case, all waters
faecally polluted may be capable of producing this disease
when all the circumstances are favourable, and therefore
must be looked upon with the gravest suspicion, whatever
the results of bacteriological or chemical analyses.
All surface waters contain large numbers of micro-organ-
isms, but freshly-drawn deep-well waters, and waters from
deep-seated springs, are almost sterile. When such pure
waters are kept for a few days, however, the number of
micro-organisms increases enormously. Professor P. Frank-
land says that such a water, containing only, say, 5 microbes
per cubic centimetre when freshly drawn, may, even if kept
in a sterile flask and protected from aerial contamination,
contain, after a few days, perhaps 500,000 in the same
volume, or, in other words, as many as are found in slightly-
diluted sewage. He points out, however, that whilst in
sewage the numbers only gradually diminish, in these
pure waters " after the rapid increase in numbers follows a
correspondingly rapid decline, so that the numbers again very
soon fall below those found in impurer surface waters." It
follows, therefore, that the purest water which has been
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190 WATER SUPPLIES
kept a few days may be confounded with a water from the
filthiest source, and that even if the number of micro-organ-
isms found in a water is to be taken as a criterion of its
purity or otherwise, the bacteriological examination must be
made before such multiplication can have ensued. In freshly-
drawn deep-well and spring waters there should be few or
no bacteria ; in the purest mountain streams and lakes there
should not be more than a few hundreds in a cubic centi-
metre (15 drops). In ordinary river waters from 1000 to
100,000 may be found in the same volume, whilst in sewage
there may be several million. Rain, hail, snow, and ice are
not free from bacteria, though usually the number contained
therein is small.
In 1887 Professor W. R. Smith made a series of experi-
ments for the Local Government Board (vide Report of the
Medical Officer, 1887) on the differentiation and identification
of micro-organisms found in water supplies. The results
gave evidence of the multifarious character of the organisms
in question, and illustrated the need for caution against
drawing general conclusions from the results of cultivating
water organisms by any single method. In the same year
Dr. Dupre, F.R.S., reported to the Board on changes effected
in the aeration of certain waters by the life processes of
particular micro-organisms under different conditions of
temperature, light, and nutrient material, but the results
obtained seem of no practical value. " The process of oxygen
consumption was found, as might be expected, to be in-
fluenced by these circumstances, but it would not yet be
safe to formulate general inferences from the facts."
Koch, in an able article on Water Filtration and Cholera, 1
has endeavoured to set up a standard of purity based upon
the number of bacteria, capable of cultivation in certain
media, contained in a given quantity of the water. He
would regard even filtered river water containing over 100