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WATER    SUPPLY
CONSIDERED MAINLY FROM A
Chemical and  Sanitary Standpoint.
                  BY


       WM. RIPLEY  NICHOLS,
                     •«. *
PROFESSOR AT THE MASSACHUSETTS INSTITUTE OF TECHNOLOGY.
FOURTH EDITION.
SECOND THOUSAND.  J  ' *? fJj^JJ'Y
       NEW YORK:     /  '/ /j ~1 £ £> ,

JOHN WILEY &  SONc

           1894.
rs.*  -—/---- 
     WAA




      1294




  Copyright, 1S83,
By W. R. NICHOLS.
  PRESS OF J. J. LITTLE i. CO.,

NOS. 10 TO 20 ASTOR PLACE, NEW YORK. 
PREFACE.
    The following  pages contain, somewhat amplified, the sub-
 stance of a course of " Lectures  on Water  Supply " which the
 author has been in the habit of delivering before certain classes
 at  the Institute of Technology.  It is primarily as an aid to
 engineering and other students at this and  similar institutions
 that  the book is printed.  It is hoped, however,  that the  book
 will be found  of service to young engineers, to persons in charge
 of  water  works, to water committees,  and  to others  who are
 interested in the matter of water supply.
    The aim is not to present a complete treatise on water supply
 for the civil engineer, nor a treatise on water analysis for the
 chemist, nor a treatise on mycology for the botanist, and  certainly
 not a treatise on sanitary science  for the physician, but, rather,
 to occupy a territory which encroaches on the fields of these and
 other professions and which belongs exclusively to no one  alone
 —ground, in  fact, with  which  all who  are  professionally  inter-
 ested in water supply must be more or less familiar.
    The metric system of weights and measures  is used, as well as
 the English;  tables for  the conversion of one system  into the
 other will be  found at  the end of the  volume.  In the nomen-
 clature of chemical substances, the old  and more  familiar terms
 are generally—although  not exclusively employed—such as car-
 bonate of  soda and not sodic carbonate, sulphate of lime rather
 than sulphate  of calcium.
   The author has quoted freely  from  other works  on the sub-
ject, and from his own earlier reports, now mostly out  of print. 
iv
PREFACE.
He would  acknowledge especial indebtedness  to the Reports of
the Rivers Pollution Commission, and  to  Fischer's  chemische
Technologie des Wassers, and regrets that  Wolffhugels Wasser-
versorgung did not come to hand until the manuscript was in
the hands of the printer.
  Massachusetts Institute of Technology,
     Boston, Mass., May, 1883. 
TABLE  OF  CONTENTS.
 Introductory Chapter.—Solution...............    i-  16
      Solution of solid substances.—Saturated and supersaturated solu-
    tions.—Condition of mixed solutions.—Various means of hastening
    solution.—Effects of dissolved solids.—Solution of gases.—Supersat-
    urated solutions of gases.—Facilitating gaseous solution.—Solubility
    of liquids in water.—Distinction between solution and suspension.

 Chapter I.—Drinking  Water and Disease.......   17-28

 Chapter II.—Water  Analysis....................   29-  47
      Suspended matter.—Dissolved gases.—Total solids in solution.—
    Chlorine. —Hardness. — Combined  nitrogen. — Organic  matter.—
    Standards of purity.—Popular tests.—Collection of samples.

 Chapter III.—Rain Water as a Source of Supply.   48-  55
      Examination of cistern water.—Natural and artificial ice.—Chemical
    examination of ice.

 Chapter IV.—Surface Waters as Sources  of Sup-
   ply.............................................   56-  78
      Turbidity of streams.—Pollution of streams.—Self-purification of
    streams.—Oxidation.—Deposition.—Dilution.—Prevention of pollu-
    tion.

Chapter V.—Surface Waters  as Sources  of Sup-
   ply  {continued/)..................................   79-104
      Animal and vegetable life.—Odors and tastes.—Temperature.—Ex-
    amination of surface waters.—Variation of surface waters.

Chapter VI.—Ground Water  as a Source  of Sup-
   ply.............................................  105-132
      Methods of utilizing ground water.—Effects of pumping on ground
    water.—Driven wells.—Natural filtration.—Examination  of ground
    water.—Pollution of domestic wells.—Examination of wells. 
vi                   TABLE OF  CONTENTS.
                                                          PAGES
Chapter VII.—Deep Seated  Water  as a  Source
  of Supply......................................  I33_I4S
     Artesian wells.—Deep wells.—Characteristics and examination of
   deep seated water.

Chapter VIII.—Artificial Improvement of Natu-
  ral Water.....................................  146-180
     Sedimentation.—Storage. — Aeration. — Filtration. — Principles of
   sand filtration.—Practical results of artificial filtration.—Sand filtra-
   tion in the United States.—Advantages of covered filter beds.—Ex-
   pense.—Other filtering materials.—Household filtration.

Chapter IX.—Artificial Improvement of Natu-
  ral Water {continued)...........................  181-193
     Softening of hard water.—Temporary hardness.—Permanent hard-
   ness.—Chemical processes.—Distillation.

Chapter X.—Some General Considerations......  194-215
     Quantity and waste.—Conduits and distribution pipes.—Service
   pipes.

Bibliography.....................................  216-220

Tables for  Calculations........................  221-225 
INTRODUCTORY   CHAPTER.
SOLUTION.
    No water which occurs in nature is pure in the strict chem-
 ical sense of the term, but all  natural waters, however free from
 suspended particles of foreign matter  which  are visible to the
 eye,  invariably  contain in solution  more or less of substances
 which, in their ordinary condition, are solids or gases.  It  is
 therefore important, in the beginning, to  understand some of
 the many things which might  be said of solution in general.

                  Solution of Solid Substances.
    If some pure salt be put  into water, after a time the salt dis-
 appears from sight, and becomes incorporated with the water, so
 that it  is  no longer possible to distinguish it  by the  eye, or to
 remove it by ever so fine a filter.   As far  as we can make it out,
 the change that has taken place is  as follows:  The ultimate par-
 ticles of the salt (the  molecules of the chemist)  are  no longer
 held together in a solid mass by that mutual attraction which we
 call cohesion, but have become separated from each other and
 distributed among  the particles (molecules) of the water so as to
 form  a  homogeneous mixture.  As far as we can perceive, it is,
 indeed,  simply a  mixture—a  mixture of particles of salt with
 particles of water—we  can discover no  chemical change,  we can
 trace no chemical action between  the dissimilar substances, salt
 and water.  This is an example of  what is usually called physical
solution.   The solution  differs, of course, essentially from the
water.   The transparency is  not  noticeably impaired,* but  if

    * This would not be true if, instead of common salt, we had taken a strongly
colored substance like the permanganate of potash.  In such  a case the strong color
of the solution would perceptibly diminish its transparency ; otherwise  the phenom-
ena would be as above. 
2
introductory chapter.
much salt  has been used  the mobility of the water has  been
lessened, the boiling point  has been raised, the  freezing point
and  the  temperature of maximum density have  been lowered,
the specific gravity, the specific heat and the electrical resistance
have also been changed.   If, now, the solution  be allowed to
evaporate at  the ordinary temperature, or if the evaporation be
hastened by artificially raising the temperature, the water passes
off as vapor and the salt is recovered unchanged.
   If a strip of  zinc be immersed in ordinary  muriatic (hydro-
chloric)  acid  somewhat diluted,  the  zinc gradually  disappears,
but at the same time there is  a marked effervescence, due to the
escape of hydrogen gas, as well  as  a  considerable  increase of
temperature.   There is, in fact, evidence enough  that  chemical
change is taking place.  When the  action is  over,  we have a
transparent liquid which is  sometimes spoken  of  as a " solution
of zinc," and the phenomenon is spoken of as chemical solution.
If, however, we study the action that occurs, we find that it may
be regarded as taking  place in two steps: in the  first place, the
zinc  acts on the acid to set free hydrogen gas, and to form a new
compound, chloride of zinc; in the second place, the chloride of
zinc  thus formed dissolves in the liquid present, as did the salt in
the previous example.
   Using the term solution in its ordinary sense, to cover all
cases of the disappearance of a solid * in a liquid, there are many
cases which can be assigned  without hesitation  to  one or the
other of the two classes of actions just described, but it is by no
means easy in  all cases  to  say whether we are dealing with a
simple (physical) solution, or whether chemical action also takes
place.  Thus, if dry oxide of  sodium be put into water, it dis-
solves, that is, the solid disappears, but we are  quite sure in this
case that it is not the oxide of sodium which exists in the  solu-
tion; in  fact, the oxide of sodium combines  chemically with a
portion of the water to form  hydrate of sodium,f and  it is  this
hydrate,  and  not the oxide, which actually dissolves in the mass
of the water present.   Again, if dry carbonate of soda be  put
into  water, there is next to no doubt that it  combines with a
  * The solution of gases and liquids will be considered further on.
  f The chemical change which takes place is thus symbolized :  Na20 + HaO =
2NaOH. 
SOLUTION OF SOLID  SUBSTANCES.
3
 portion of the water, and  that the compound which  actually
 enters into solution has the same composition as the crystallized
 carbonate which contains, in addition to the elements of carbonate
 of soda, also a quantity of water.   With  regard to  many solids,
 we are in doubt whether they  dissolve simply as such, or first
 undergo  chemical change.  In  cases like that  of common salt,
 first mentioned,  we can trace no such chemical change,  but it is
 by no  means  certain that no chemical action  takes place, and
 many regard the solution of salt and other similar substances as
 due to  the same cause as that to which chemical action  in gen-
 eral is due, manifested, however, to a slight degree.*
    The term solution is applied almost exclusively to cases where
 the  dissolving substance, the solvent, is a liquid; the substance
 dissolved may be solid, liquid, or gaseous.   Every liquid can act
 as a solvent  for certain things, although, if the liquid is  of a
 marked alkaline or acid character, solution is usually accompanied
 by chemical change.  Water is  spoken of as the universal sol-
 vent, and more  than any other liquid does it  dissolve various
 substances without evident change.  In what follows, we shall
 use the terms soluble and insoluble to mean soluble and insoluble
 in water.
   Solids  differ from  each other very much in  the  facility with
 which they may be dissolved in water; thus, chloride of calcium,
 if merely  left exposed to the air, readily absorbs from the atmos-
 phere enough water to  dissolve it, and is an example of a so-
 called deliquescent substance ; on the other hand, sulphate of lead
 requires about 23,000 times its own weight of water (Fresenius),
 and quartz may be said to be insoluble. At a given temperature
 a certain quantity of water will always dissolve  the same weight
 of a  particular  substance,  and,  as a general  rule, the  amount
 which can be dissolved increases with increase  of temperature.
 The effect of increased temperature, however, differs greatly with
 different substances.  Thus chloride of sodium (common salt) is
 more soluble  in  hot than in cold  water, but only very  slightly
 so; in the case of chloride  of potassium, however, the amount
 dissolved increases regularly with the temperature, while in the
case  of  nitrate of potassium  the  increase of  solubility for  a

   * See,  for instance,  a paper On Solution and the Chemical Process. Hunt's
Chemical and Geological Essays, pp. 448 and foil. 
TRODUCTORY  CHAPTER.
Fig. i.— curves of solubility.
given increase of temperature is greater  the higher the tempera*
ture:
        DIFF. FOR
GRAMS.     io".
34-70,
40.18 f   5
100 grams of water at  o° C. dissolve of chloride of potassium. 29.23 I

                   403
                   f.o'
100 grams of water at  o° dissolve of nitrate of potassium.
                   20°
                   40°
                   60°
 45-66 }   5
 13-32 j.  l8
 31.70
 63-97   32
110.33 f  46 
SOLUTION OF SOLID  SUBSTANCES.
5
   The diagram on the opposite page shows the relation of solu-
bility to temperature in the case of a number of common salts.
The horizontal lines indicate the number of parts by weight of
the salt which ioo  parts by weight of water will dissolve at the
indicated temperature.
   There are some remarkable exceptions to the general rule
that a larger amount of a substance can be dissolved  in a given
quantity of hot water than in the same quantity of water at a
lower temperature.   Sulphate of lime is one of these exceptions.
This substance occurs in sea-water and in other natural waters,
and, by virtue  of  the fact  that its  solubility decreases with
increase of temperature, it gives much trouble in steam-boilers
by separating out from the water and forming a coherent scale.
The following table shows the  solubility of sulphate  of lime in
sea-water at temperatures above 1030 Centigrade.
TABLE I.—Solubility of Sulphate of Lime in Sea-Water.*
			Sea-water Saturated with		Sulphate of
Temperature in Degrees				Lime	
Centigrade.	Fahrenheit.	Pressure in Atmospheres.	Marks (at 150 C)on Beaum^'s hydrometer.	Or has a specific gravity of	Contains per cent of sulphate of lime.
103.	217.4	I.	12°.5	I.090	O.5OO
103.80	218.8	I.	12°	I.085	O.477
105.15	221.3	I.	11°	I.078	O.432
108.60	2275	1-25	'0°	I 070	o-395
III.OO	231.8	1.25	9°	I.063	0-355
113.20	235.8	1-25	8°	I.056	0.310
115.8c	240.4	1.50	7°	I 048	0.267
118.50	245-3	1.50	6°	1.041	0.226
121.20	250.2	I 50	5°	I.034	0.183
124.	255-2	2.	4°	I 027	0.140
I27.9O	262.2	2.	3°	1.020	0.097
130.	266.0	2.50	2°	I-013	0.060
I33-30	271.9	2.5O	1°	I.007	0.023
   This table shows that when sea-water is boiled under a press-
ure of one  atmosphere, or at  a  temperature of 1030 C, it will
become saturated with sulphate of lime, when, by evaporation,
its density has been elevated to I2°.5 Beaum6, and it will then
contain 0.5 per cent of  the sulphate; at  1.25  atmospheres, or
io8°.6 C, the  water will be saturated with sulphate when  it

  * Couste' : Annales des Mines, v (1854), p. 80. The second and fifth columns
have been added to Couste's table. 
6
INTRODUCTORY  CHAPTER.
 marks io° B., and  will then contain 0.395 per cent of the sul-
 phate.  At a pressure of two atmospheres, that is, at a tempera-
 ture of about 1250  C, sea-water, in its natural state  and without
 having undergone  any concentration, is very near the point at
 which saturation occurs, for the density of sea-water is from 30
 to 30.5 B., and this, according to the table, would correspond to
 a temperature of about 1250 C.  Sulphate of lime becomes com-
 pletely insoluble, either in fresh  or sea-water, at temperatures
 between 1400 C. and 1500 C. (284°-302° F.).
    Saturated and  supersaturated solutions.—At  any particular
 temperature a solvent  can take up a definite  amount of  a sub-
 stance soluble  in it, and no more.  The solution is said  to  be
 saturated when it contains as much of the dissolved  substance as
 can be taken up at the given temperature.   It  is, however, often
 possible  to prepare what are called supersaturated  solutions, by
 making a saturated solution at some higher  temperature and
 allowing the liquid  to cool.  Suppose, for example, that a satu-
 rated solution  of nitrate  of potassium was made at 6o°  using
 100 c.c. of  water; according to  the diagram on page 4, at that
 temperature 100 grams of water would dissolve 110.33 grams of
 the salt.   If, now,  the solution were cooled to 200, we should
 expect that there would then remain dissolved  31.70 grams, and
 that 78.63 grams would separate  in the solid  condition during
 the cooling; in  this particular  case, the expectation would be
 approximately realized ; but, with  many salts, if a saturated solu-
tion be cooled quietly without  agitation, it happens that,  when
cold, the  liquid still  retains  more of the salt than it could take up
at  the lower temperature.  In  fact, Storer says:* "It is  often
exceedingly difficult thus to obtain normally saturated solutions,
even of our most common and easily crystallized salts, within the
limits of time which can be conveniently allotted  to a  single
experiment."
   In the case of some particular salts the phenomenon of super-
 saturation  is very marked.  Thus, at a temperature of 330 C,
 water will dissolve  about half its  own weight  of  Glauber's salt
 (hydrated sulphate of sodium), and if the  solution be protected
 from dust and allowed to cool  quietly to the ordinary tempera-
 ture, the whole of the compound  remains in solution.  If, now,
* Dictionary of Solubilities, Preface. 
SOLUTION OF SOLID SUBSTANCES.
7
a small crystal of the same kind as the original salt be dropped
into the solution, about  three-fifths of the salt  separates out in
the crystalline form, and the whole mass becomes nearly solid.
    Condition of mixed solutions.—Natural waters usually contain
a variety of  foreign  substances, and  it is worth while, at this
point, to  inquire into the condition of things which exist in a
dilute solution containing at the same time several different salts.
We will first  take a simple case where chemical analysis shows
the existence of, say a chloride and a sulphate, and  of potassium
and sodium.  The question may be asked, whether the solution
contains chloride of sodium and sulphate of  potassium, or  sul-
phate of sodium and chloride of potassium, or whether all four
of  these compounds  exist at  the  same time.  Now, while  the
latter is believed to be  the true state of the case,  chemical
analysis is powerless  to  answer the question, and two solutions
undistinguishable from each other could be prepared by taking
each  pair of salts indicated above in the right proportion.*  If a
number of soluble salts are mixed together in solution, the matter
becomes more complicated, but in stating  the  results of analysis,
certain conventional forms of statement are adopted.   Thus we
might mix together in dilute solution and in the right proportion,
sulphate of sodium and  chloride of calcium, but if the solution
were  analyzed, it would be  reported  as containing sulphate of
calcium and chloride of sodium, for the reason that the sulphate
of  calcium  is much  less readily soluble in water than the other
compounds, and if the solution in question were gradually con-
centrated by evaporation, the sulphate of calcium would separate
in the solid form ; if the  evaporation were  carried to dryness, the
sulphate of calcium  and chloride of sodium would remain, each
crystallized by itself.  For this reason chloride of calcium would
never be represented  as  existing in the presence of sulphate of
sodium, although, in  a dilute solution, it is probable that a por-
tion of the calcium would actually exist in the form of  chloride.
It should be  said that much difference of opinion  and practice
exists with reference to  the best way to  represent the constit-
uents  of a  mixed solution, and two chemists will  often report

   * We are not in absolute ignorance as to the laws which govern  the partition of a
base among different acids, or of an acid among different bases, or, indeed, of the acid
and basic radicals among different salts.  Our knowledge, however, is too limited to be
applied practically to any considerable extent in such a case as that of a natural water. 
INTRODUCTORY CHAPTER.
very different statements of the  analysis of the  same solution,
while the numerical results actually obtained are the same.
   The following statement of  the analysis of Croton water, by
Professor Chandler, is an  example  of the  form  in which such
reports are usually made :
Solids Contained in one Gallon of Croton Water.
Chloride of Sodium.......
Sulphate of Potash......
Sulphate of Soda.........
Sulphate of Lime.........
Bicarbonate of Lime......
Bicarbonate of Magnesia..
Silica...................
Alumina and  Oxide of Iron
Organic Matter...........

       Total...........
6.873
Summer, 1869.	May 11, 1872.
Grains.	Grains.
O.402	O.284
O.179	O.205
0.260	O.024
O.158	O.024
2.670	2-331
I-9I3	1.338
O.621	0.222
a trace	O 058
0.670	O.874
5-360
   The following statement represents the actual results of  an-
alysis, from which the previous  statement was made up  accord-
ing to the conventional plan usually adopted :
Solids Contained  in one Gallon of Croton Water.
Soda...............................
Potash.............................
Lime..............................
Magnesia...........................
Chlorine............................
Sulphuric Acid......................
Silica..............................
Alumina and Oxide of Iron...........
Carbonic Acid (calculated)............
Water in Bicarbonates (calculated).....
Organic and Volatile Matter..........


Less Oxygen equivalent to the Chlorine

       Total......................
Summer, if
  Grains.
 O.326
 O.097
 O.988
 O.524
 O.243
 O.322
 0.621
1 trace
 2.604
 0-532
 0.670
6.927
0.054
6873
May 11, 1872.
  Grains.
0.157
0.109
O.819
O.369
0.172
O.124
0.222
O.058
2.074
O.42I
O.874
5-399
0.039
5.360
    Effect of the presence of one substance on the solubility of another
substance.—When water  has dissolved  as much of  a given sub-
stance as it can  under the existing conditions, it is still able to
take  up more  or less of a second  substance.  In general  the 
SOLUTION OF SOLID  SUBSTANCES.
9
presence of one substance in a solution will modify the  action of
the liquid on  another substance presented to  it; thus, while
cyanide of silver is insoluble  in water, it dissolves readily in an
aqueous solution of cyanide of potassium.  Again, although car-
bonate  of lime dissolves only to a very slight  extent  in  pure
water, it dissolves to  a considerable extent in water containing
carbonic acid,  and is a  frequent constituent  of natural  waters.
When such waters are boiled, the carbonic acid escapes, and as
the water is no longer able to keep the carbonate of lime in solu-
tion, this  compound  separates out and is one of the substances
which cause trouble in steam boilers by forming an incrustation
or scale.  Undoubtedly, in such cases as those mentioned, chem-
ical action takes place to a greater or less extent between the
substances dissolved.
    Various means of hastening solution.—-The solution of  a  solid
substance is facilitated by any means which tends  to bring con-
tinually fresh portions of the  solvent into intimate contact with
the substance  to be dissolved.  It is consequently of advantage
to reduce the solid to a fine powder, and  to agitate the mixture.
Where there is no objection to heating the liquid, the solution is
facilitated by  so doing.   Advantage may be taken of the  fact
that the solution has  a greater specific gravity than the solvent,
by suspending the solid near the sur-
face of the  liquid.   This may be
easily shown by putting crystals of
some colored  salt, as bichromate of
potash  or sulphate of copper, into a
cone of wire gauze, or into a funnel,
or into a tube over one end of which
a piece  of cloth is tied, and suspend-
ing the apparatus in a vessel of water.
The solution,  as  it  is  formed, falls
toward  the bottom  of  the  vessel,
marking its path  through the water
by colored threads, and this action continues until the solution is
saturated.
   In preparing brine or a solution of copperas—as a disinfectant,
for instance—much time may be saved by suspending the salt or
the copperas in a basket or coarse bag near the top of the tub or
barrel in which the solution is made, instead of putting the solid
Fig. 2. 
10
INTRODUCTORY CHAPTER.
at the bottom of the water and endeavoring to hasten solution
by stirring.
   Effect of dissolved solids on various physical phenomena.—The
effect of dissolved solid  substances  is  to  increase  the  specific
gravity, and in  the  case  of  many substances tables have been
prepared from which the  percentage of  the substance dissolved
can be learned by observing  the specific gravity of the solution.
Similar tables have also been prepared for solutions of gases and
liquids.
   The presence of  dissolved substances raises the boiling point
of the solution,  and the stronger the solution, the  higher the
boiling point.   Thus, ordinary sea-water boils  at  about  ioi° C.
(2130.8 F.), while a saturated solution of acetate of  potash does
not boil until the temperature reaches 1690 C. (3040.2 F.).
   The effect of dissolved solids  is to lower the  freezing point
and  the  temperature of  maximum density.   Thus, while pure
water is at its maximum  density at 4° C. (390.2 F.), and freezes
at oc C.  (320 F.), sea-water, according to Despretz,  acquires  its
maximum density at 30.67 C. (380.6 F.), and freezes at —1°.88 C.
(280.6  F.).
                      Solution of Gases.

   It is true of gases  as  of  solids that  they vary very much in
their deportment toward  water, some being absorbed by it with
very great readiness, while others may be kept  in contact with it
for a long time without  suffering  any considerable  decrease  of
bulk.  It is generally true, however, of gases, that they dissolve
to a certain, even if to a slight, extent, and the amount is fixed
and  definite under the  same conditions of temperature and  press-
ure.  As a rule, increase of temperature decreases  the solubility,
and  by prolonged boiling, water  may be  freed from the gases
which it  holds in solution.*  The  specific gravity of  solutions of
gases is sometimes lower and  sometimes higher than that of water.
   The volume  of  a  gas (expressed in cubic centimeters and
measured at o° C, and under a pressure of  760  m.m. of mercury)
which  one cubic centimeter of water will  dissolve at a certain
   * This is not invariably true.  Thus, a strong solution of chlorhydric acid gas,
when heated, gives off the gas until the amount of acid in the remaining solution has
been reduced to 20.24 per  cent by weight; the solution of this strength distills
unchanged at no° C. 
SOLUTION  OF GASES.
II
temperature, is called the coefficient of absorption at that tem-
perature.  The accompanying table gives the coefficient of absorp-
tion at various temperatures for oxygen, nitrogen, carbonic acid,
and ammonia.*
TABLE II.—Coefficient of Absorption of various Gases.
Temperature.	Oxygen.	Nitrogen.	Carbonic Acid.	Ammonia.
o° C.	O.04114	O.02035	I.7967	1049.6
i	O.04007	O.OI981	I.7207	1020.8
2	O.03907	O.OI932	I.6481	993-3
3	O.03810	O.O1884	L5787	967.0
4	O.03717	O.OI838	I.5126	941.9
5	O.03628	O.OI794	I.4497	917.9
6	O.03544	O.OI752	I•3901	895.0
7	O.03465	O.O1713	1-3339	873.1
8	O.03389	O.OI675	1.2809	852.1
9	O.03317	O.O1640	1.2311	832.0
IO	O.03250	O.OI607	1.1847	812.8
n	O.03189	O.OI577	1.1416	794-3
12	O.03133	O.OI.549	1.1018	776-3
13	O.03082	O.OI523	1-0653	759-6
14	O.03034	O.O1500	1.0321	743-1
15	0.02989	O.OI478	1.0020	727.2
16	O.02949	O.OI458	0-9753	711.8
17	O.02914	O.OI44I	0.9519	696.9
18	O.02884	O.OI426	0.9318	682.3
19	O.02858	O.O1413	0.9150	668.0
20	O.02838	O.OI403	0.9014	654-0
   From the table it is seen that the coefficient of carbonic acid
is  considerably, and that of ammonia enormously, greater than
that of oxygen and nitrogen.  In the case of gases like ammonia,
hydrochloric acid, etc., we have no difficulty in believing that the
great  absorption is due to the fact that chemical combination
takes  place, and this is probably true also of carbonic acid, sul-
phuretted hydrogen, etc.  It is a curious fact that, with hydrogen,
the coefficient of absorption in water is the same at ajl tempera-
tures  from o° to 200 C.
   If  the pressure be increased, a  greater weight of the gas is
dissolved  at a given temperature,  and the increase  is,  in  fact,
proportional to the increase of pressure, but since the increased
pressure diminishes the volume of  the gas in the same  propor-
tion, the same actual volume of gas is dissolved  whatever the
pressure.  In the case of gases which are easily liquefied by press-
ure, or of those which are very soluble in water, this law  does
not hold good  under all circumstances.   Thus carbonic acid fol-
* Bunsen : Gasometrische Methoden, Braunschweig, 1877. 
12
INTRODUCTORY  CHAPTER.
lows the law only when the pressure is small, and ammonia gas
only at high temperature.  The law is, in general, true also when
water is exposed to an atmosphere of mixed gases ; that is, each
of the gases in the mixture is  dissolved according to  its own
coefficient of solubility;  but in determining the actual quantity
of any one gas dissolved {i. e., the volume at o° and 760 m.m.), it
must  be remembered  that  the  pressure exerted  by the mixed
gases is made up of the partial pressures of the  several gases in
the mixture. Thus, whether water at o° C. be exposed to pure
oxygen with a pressure of  760 m.m., or to air at the pressure of
760 m.m., the same volume of oxygen will be  dissolved in either
case, namely, as we see from the table, 0.04114 c.c. of oxygen in
each cubic centimeter of water; but  in the  one case we  have
0.04114 c.c.  of oxygen with a pressure of 760 m.m., whereas in
the other case we have 0.04114 c.c. of  oxygen with a pressure of
one-fifth of 760 m.m., for in the air the oxygen forms only about
one-fifth part by volume.   It follows that the actual quantity of
gas {i. e., the volume which it would have at o° and 760 m.m.) in
the first case is about five times  as great as in the second.   It is
possible, knowing  the  composition of the mixture of dissolved
gases in any case, to calculate the composition of the atmosphere
to which the water was exposed, but  this does not  hold in the
case of a gas forming only a very  small part of a  mixture.
Owing to the fact that the  coefficient of absorption for oxygen is
greater than that of nitrogen, water which has been exposed to
ordinary air  contains these  two gases in quite a different propor-
tion from that in which they exist  in  the air, and this  is one of
the proofs adduced to  show that in the air the gases were simply
mixed together, and not chemically combined.   The relation is
as follows:
                           Composition of Air   Composition of " Dissolved
                             by Volume.        Air " by Volume.*
        Oxygen...................  20.96               34-91
        Nitrogen..................  79.04               65.09
                              100.00              100.00

   Supersaturated solutions of gases.—As in the case of solids, it
is possible  to prepare temporarily supersaturated  solutions of
gases.   Thus, if  ordinary " soda-water " be drawn from a siphon
or from a fountain, a quantity of gas escapes as  soon as the
Bunsen : Gasometrische Methoden, p. 224. 
SOLUTION OF GASES.
13
excess of pressure is removed.   Afterward the gas escapes more
slowly, until  eventually  the water contains no  more carbonic
acid gas than it would take up under  the conditions to which it
is now exposed.  That we really are dealing with a supersaturated
solution after  the first rapid escape of gas, may be shown  by
dropping into the  soda-water  a teaspoonful of sugar, or some
sand, or almost any powder ; this causes immediate effervescence
and escape of gas by furnishing free surfaces and sharp angles  for
the collection and liberation of the gas within the liquid.
    Facilitating gaseous solution.—In preparing a  saturated solu-
tion of  a gas, the  latter is generally  allowed to  simply  bubble
through the liquid to be saturated until the end  is attained, the
liquid being agitated  or  not, according to convenience.   In the
case of most  gases, solution is  facilitated  by lowering the tem-
perature, as,  for instance, by surrounding the vessel in which the
absorption takes place with cold water or ice. This is of especial
use when the gas  enters into  chemical combination  with the
liquid, as is true of ammonia, hydrochloric acid,  etc., when dis-
solved in water, because the heat of  chemical action raises the
temperature  of the solution.
    It  is sometimes desirable to charge water with gas under
increased pressure ; thus water is  charged  under pressure with
carbonic acid gas, to bear thenceforth the name of " soda-water ; "
sulphuretted  hydrogen water, for use  in chemical laboratories, is
also prepared similarly.

                Solubility of Liquids  in Water.

    Like solid  substances, liquids differ among  themselves as to
their  solubility in water, some liquids,  as glycerine and common
alcohol,  mix  with water in any  and all proportions;  others, like
ether and amylic alcohol, dissolve to a limited and definite extent;
others,  like some oils  and mercury, seem  to be altogether  in-
soluble, although by long contact with  the water such insoluble
liquids may undergo chemical change, and give  up something to
the water.  It is more difficult than with  solids to determine
whether and  to what  extent an insoluble  or difficultly  soluble
liquid dissolves in water, and to distinguish between solution and
suspension, especially if the liquid is colorless and has nearly the
same  refractive index as water.  In this case it is impossible to 
14
INTRODUCTORY  CHAPTER.
obtain satisfactory indications with the eye, and complete separa-
tion of suspended particles is often impossible.  The solution of
a difficultly soluble colorless liquid may sometimes be watched
by coloring the liquid with some substance which does not inter-
fere with the action.  Thus, if amylic  alcohol be colored with a
little iodine, the process of solution may be followed more readily
than would otherwise be possible.
   As in the case of  solids and gases, we have the same grada-
tion from cases of  marked  chemical action, accompanied  by dis-
play of heat and decrease of bulk, to cases where we seem to be
dealing with a simple mechanical mixture.

         Distinction  between Solution and Suspension.

   There is a great deal of confusion, even among well-educated
people, as to the proper use of the  terms in solution and in  suspen-
sion, and in the same  connection it may be said that a great deal
of confusion exists with  reference to the distinction between
clear  and colorless,  terms  which are by no means  synonymous.
The accurate use of the terms can probably best be made plain
by illustrations.  If, to  take an example already made use of, we
put some common salt into a quantity of  water, after a time the
salt disappears, the ultimate particles being distributed through
the water so that they are  no longer  distinguishable by the eye,
even aided  by the most powerful microscope; the salt cannot be
removed by simple filtration ; and, although the solution is some-
what  less mobile than water, it is  still transparent.  This, as we
have  seen,  is a case  of solution.  Suppose that, instead  of the
salt, we take a quantity of sulphate of copper (blue vitriol).  The
phenomena will be similar, but the blue color of the compound
shows itself in the solution.  The more  concentrated  the solu-
tion, the more will its  transparency  be diminished on account
of the depth of color; it is easy, however, by taking a thin layer
of the solution to  satisfy one's self of the transparency of the
liquid and of the absence of suspended particles.  Such a liquid,
although colored, is clear.
    Suppose, now, we take  some clay, shake  it with water, and
then allow  it to settle.  The grosser particles will subside to the
bottom of  the vessel, but the finer particles will remain  in  sus-
pension.  Very finely divided clay will refuse to settle for weeks 
      DISTINCTION BETWEEN SOLUTION AND SUSPENSION.    15

 and sometimes even for months.   In such cases the liquid appears
 somewhat turbid and opaque; and, although the individual par-
 ticles are too fine to be readily removed by ordinary filters and
 too small to be distinguished as particles by  the eye, still the
 clay has  not dissolved, and the very turbidity  or opacity of the
 liquid shows the presence of solid particles, although  they are
 extremely minute.  Such an appearance is not to be described as
 "being colored," although finely divided clay and other material
 may be suspended in a liquid which does of  itself  possess a dis-
 tinct color.  One often meets with the expression, and that, too,
 in standard works, " the water is discolored by clay," when really
 it is a question  of a  colorless water carrying  particles of  clay in
 suspension.  As we shall see further on, surface waters are often
 highly colored  by vegetable extractive matter in solution, but
 the water may at the same  time  be perfectly clear and transpa-
 rent.  On the other  hand, pond waters often  appear decidedly
 green; but simple filtration gives a colorless water, and shows the
 green color to have  been due to particles of  green (vegetable)
 matter which were suspended in the liquid.
    While for practical purposes there is no  difficulty in  distin-
 guishing that which is really dissolved from that which is  merely
 held suspended, and in applying the terms as already indicated,
 it is true that there are substances, generally considered insoluble,
 which admit of  such minute subdivision that the finer particles
 will remain suspended in water for months, giving in some cases
 a faint opalescence to the liquid, but  in other  cases  apparently
 only a color.  Thus, by trituration with milk-sugar, metallic gold
 may be reduced to so fine a condition  that it will diffuse through
 water, giving it a purple color, and it is hard to  say that the gold
 does  not  exist  in solution;  after long standing, however, the
 metal separates  out and  settles to the bottom of the liquid, and
 this separation may be hastened by the addition of certain saline
 solutions.*   The action of  the saline solution is not fully under-
stood, but it was  noticed  long ago  that  these  minute  particles
showed under the microscope the so-called Brownian motion, and
that the  addition of  small  quantities of  alum, glue, lime, car-
bonate of ammonia or other salts, caused this molecular motion

  * Buchmann : Beobachtungen und Untersuchungen zum Nachweis der Loslich-
keit  von Metallen, etc.  Leipzig, 1881, p. 54. 
i6
INTRODUCTORY CHAPTER.
to cease, and the particles to flock together and  settle out as
minute, amorphous, curdy masses.*   The  same thing is  illus-
trated  on the large scale by the  phenomena which take place
when a river, like  the  Mississippi, loaded with  silt, meets the
waters of  the ocean.   Dr. Huntf found  that water taken neai
the mouth of the Mississippi contained about -^^Vo  °f suspended
matter, mainly clay, which required from ten to fourteen days to
subside.   He, however, observed that the addition of  sea-water
or of salt, sulphate of magnesia, alum, or sulphuric acid, rendered
the water clear in from twelve  to eighteen hours,  owing to this
same flocculation of the suspended matter.

              * Naumann : Thermochemie, p. 33.
              f Proc. Boston Soc. Nat. Hist., xvi, p. 301. 
WATER  SUPPLY.
                        CHAPTER  I.

                DRINKING WATER AND  DISEASE.

    WITH reference to their  use for town and household supply,
 we shall roughly divide all natural waters into four classes, as
 follows:
    I.  Rain water;
    2.  Surface water, including streams and lakes ;
    3.  Ground water, including shallow wells ;
    4.  Deep-seated water, including deep wells, artesian wells, and
 springs.
    Under each  of these heads we  shall study the advantages and
 disadvantages of the particular class of water, the liability of pol-
 lution, etc.; but first we will consider, in a general way, the con-
 nection which exists, or is supposed  by some  to exist, between
 drinking water and disease.
    A water containing a considerable amount of dissolved sub-
 stances—one which could properly be  denominated  a  mineral
 water—would not  be  thought of  for a public water supply, and
 would seldom be used  as a regular beverage except for the sake
 of real or fancied medicinal effect ; a  small amount, however, of
 mineral matter is generally considered an advantage.   The pres-
 ence of the substances which ordinarily exist in solution in natu-
 ral waters must  not be regarded as necessary, because experience
 on ship-board has shown that distilled water, properly aerated, is
 perfectly  wholesome.  It appears that distilled  water, soft sur-
 face water,  and moderately  hard* spring or well water are all
wholesome,  and may be drunk without inconvenience by persons
accustomed  to their use.  It  is, however, true that a person who

   * A hard water is, generally speaking, one which contains compounds of lime or
magnesia in solution.  See pages 33 and 181,
            2 
i8
WATER  SUPPLY.
 is in the habit of drinking  a soft water generally experiences
 some derangement of the digestive organs on beginning to use
 hard water, and vice versa.  It is contended  by some that the
 human system needs salts of  lime, etc., that these compounds are
 furnished in an assimilable form in water, and that, consequently,
 a somewhat hard water is more advantageous for town supply ;
 statistics  have been  brought together to support  this view  by
 comparing the death rate of  various towns with the hardness of
 the water supply, but the death rate depends upon  too  many
 factors to be  used as the chief argument in this connection.  It
 is, however, the result of  general observation that  a hard  water
 of which  the hardness is due to salts of magnesia or to sulphate
 of lime is not well suited for drinking, and  is  injurious to most
 persons.
   Waters, especially surface waters, containing much vegetable
 matter  are  also,  in  some cases, unwholesome.  The  water  of
 marshes is sometimes the cause of diarrhoea and other diseases
 of this character, and is supposed by some  to cause malarial and
 other fevers (see also page ioo). The mere presence of vegetable
 organic matter, however, is not sufficient to produce these effects,
 because many waters which are quite deeply colored by vegetable
 matter are proved by experience to be perfectly wholesome.*
   While some waters  are  thus,  in  their natural  condition,
 unwholesome and may be the cause of sickness, the  attention of
 sanitarians and water experts is directed nowadays principally
 to the effect of water which  is polluted by the waste  materials
 from manufactories  and dwellings, or by the  sewage  of towns
 and cities; and it is generally held, especially in England and the
 United States, that water thus polluted may be, and frequently
 is, the cause of certain specific diseases.  Before discussing this
 question directly, it  is important  to have a general idea of the
 present prevailing view with  reference to the  so-called zymotic
 diseases, and to understand what is meant by the " germ theory."
   Many clear liquids containing  organic matter of  animal  or
vegetable  origin—such, for instance, as infusions of hay, infusion
of turnip, urine, etc., etc.,—if exposed to the  air gradually be-
 come turbid or cloudy, or, perhaps, a film forms on the surface
 of the liquid, or a deposit upon the walls of the vessel which con.
* See, however, a remark by Professor Mallet, page 26. 
DRINKING WATER AND DISEASE.
19
 tains it.   The cause of the turbidity is shown by the microscope
 to be the presence  of countless minute organized bodies—some
 rod-like, others globular—which prove to be capable of self-prop-
 agation, and which  are endowed with motion, at least under cer-
 tain conditions.   Similar organisms are  found  in  the  " dust "
 which floats in the air, and which  may be collected by causing a
 current of air to impinge upon a surface moistened with  glycer-
 ine ; they occur in  rain water, particularly in that which falls in
 the beginning of a shower, in surface waters and elsewhere. They
 are found especially where there is decomposing organic matter,
 and perform an active part in promoting or producing the chem-
 ical changes which take place.  In certain diseases of men and of
 the lower animals, organisms which, in  their general character,
 are similar to those  thus described have been found in the blood
 or in the substance of various organs, and their connection with
 the disease seems to be  something more than a coincidence ;
 there seems, indeed, to be a causal connection.
    The micro-organisms with which we are now concerned  are
 referred to the vegetable kingdom ;  they are regarded as related
 both to the fungi and to the alga, and are designated  scientifi-
 cally as schizomycetes (Spaltpilze, Nageli) ;* their  study  requires
 the highest powers  of  the microscope and the greatest  skill in
 observation.   The development  of certain forms has been care-
 fully studied, and  it is known that they  multiply not  only by
 fission—as Nageli's classification impl:es—but also by the  forma-
 tion of spores or  permanent  " germs."   The " germ theory " of
 disease is that many diseases  are due to the presence and  propa-
 gation in the system of these minute organisms, which are popu-
 larly spoken of  under  the general name  bacteria, under  which
 term are  included also  organisms which, as far  as known,  are
 harmless.  Some  of the diseases which have, with more or less
 show of reason, been supposed to have their cause in such  organ-
 isms are malarial (intermittent) fever, relapsing fever, typhus and
 typhoid, cholera, yellow fever, diphtheria, and tuberculosis.
   * Nageli : Die niederen Pilze in ihren Beziehungen zu den Infectionskrankheiten,
 Munich, 1877.  Nageli distinguishes three natural groups among the lower fungi :
(1) the mucorini, Schimmelpilze, mould fungi ; (2) the saccharomycetes, Sprosspilze,
budding fungi ;  (3) the schizomycetes, Spaltpilze,  fission fungi.  The second class
includes the organisms which produce  the fermentation of wine and beer ; the third
class includes the fungi of putrefaction, the so-called bacteria.  The terms microbes,
microzymes, as well as several others, are also used to include all these micro-organisms. 
20
WATER SUPPLY.
    With reference to specific distinctions among the organisms
 themselves observers are not agreed.   Some would very much
 restrict the number  of  true species, and refer  the  differences in
 appearance and action to differences in the attendant conditions;
 others believe that  there are  many species, as distinct as those
 observed in higher organisms,  and that  each disease has its own
                                     bacterium;  they  believe
                                     that  the observed differ-
                                     ences are essential, and the
                                     inability  to recognize,  in
                                     all  cases, satisfactory spe-
                                     cific characters is due to the
                                     imperfection of the means
                                     of observation.  For  pur-
poses of study, at any rate, the various observed forms may be
classified in genera  and  species.   Referring to  a few  terms of
    *f ' Co 'O
   f p '. ■ ■ .* 4> 3 .
    »A,J, ;.#-;•%'
        a  ' "
%
Fig. 3
 in th:
a. Micrococcus prodigiosus ; b.
zooglcea stage ; c. M. Urea:.
oQe
the same
650:1.
V\. ^A<W,
w»
Fig 4. a. Bacterium termo ; b. Same in the zooglcea stage ;  c. Bacterium lineola ;
 d. Vibrio rugula j e. V. serpens ; f. Spirillum volutans ; g. Sp. tenue.  650 :1.

somewhat common occurrence,  the micrococci are  globular or
oval, the  bacilli are rod-like, the vibriones (vibrios) are sinuous,
and the spirilla  are spiral.   No  attempt to represent these mi-
nute organisms by cuts can be very successful.   Figures 3 and 4
may serve to give  a  rough  idea of the general appearance of
some of them.
   The connection of the bacteria with disease has  been most
satisfactorily made  out in the case of splenic fever (anthrax,
charbon (Fr.), Milzbrand  (Germ.),  malignant pustule).  In  this
disease the blood and various organs, especially the spleen, con-
tain an organism known as Bacillus anthracis.   Koch* cultivated
           * Cohn's Beitrage zur Biologie der Pflanzen, ii.  p. 277. 
DRINKING WATER AND DISEASE.
21
the organisms in appropriate fluids outside of the animal body, and
observed the development and the formation of spores, and from
these spores he reproduced  the specific disease in living animals.
He found  that the organisms themselves, as observed in the
blood, usually died in  a few days, but that the spores retained
their  vitality for  at least four years.  The Bacillus anthracis  in
appearance is scarcely to be distinguished  from the Bacillus sub-
tilis, a harmless form which occurs in infusions of hay, and Dr.
Buchner* has been able, as  he claims, by a series of cultivations
to transform one form  into the other,  and from  the harmless
Bacillus subtilis to obtain the Bacillus anthracis, and to prove its
identity by producing the well-marked disease in  animals.  Nat-
urally enough Buchner's conclusions are  disputed, and, until his
results are  generally  accepted  by  competent specialists, they
cannot be looked upon by the world in general as showing more
than a possibility.
   Admitting the necessary presence of these minute organisms in
the bodies of persons sick with certain diseases, organisms which,
at least in certain stages of  their development, can exist outside
the human body and  retain their vitality for a  long time, the
question arises how they can find their way into the systems of
healthy persons to produce disease.  The  two most obvious  of
the possible  carriers of  disease  are  the  air we breathe and th6
water we drink.   We have no difficulty  in supposing that ema--
nations from sick persons,  particulate or otherwise,  may find
their way into the air; moreover, the dejections of the sick and
the water  in which their  clothes or their persons have been
washed may often reach wells or other sources of drinking water.
Of these two media the  former, i. e. the air, is a priori the most
probable, partly because we take very much more air into our
lungs than we  take water into our stomachs, and also because
the lungs afford a better chance for  the organisms to enter the
blood; indeed, some maintain that  any  organisms entering the
stomach  are  rendered harmless by the fluids therein, and that
the drinking water is not to be considered at all as a means of
conveying the germs of disease.
   Of the diseases which are supposed  to be caused by  these
micro-organisms—to be propagated by germs—those which have
* Sitzb. d. math.-phys. Classe d. konigl. bayer. Akad., 1880, p. 368. 
22
WATER SUPPLY.
been, with the greatest unanimity, ascribed  to the use of impure
drinking water are typhoid fever and cholera.  With reference
even to these diseases, however, there has been much  discussion
and controversy between the adherents and  the opponents of the
"drinking-water  theory"  since  1848, when Snow,  Budd, and
others in England ascribed the spread of the cholera then prev-
alent to the drinking of water fouled by the dejections of cholera
patients.  It would be unprofitable, in brief space, to attempt to
review the numerous cases  on record  where  the coincidences
between impure water and  cholera  (and other diseases) have
been so marked as to lead able and careful investigators to believe
in the existence of  cause  and effect. The most able opponent
of the theory is Professor Pettenkofer, of Munich,  who  holds
that in these cases there is coincidence only, and that other cir-
cumstances,  and notably the character  of  the  ground and  the
condition of ground water, have  been overlooked in  the investi-
gations.  He and  his  sympathizers also bring forward  many
instances where the  connection between  a particular outbreak of
a specific disease and the drinking water previously used by those
attacked is  not  only not obvious, but  absolutely out of  the
question.
   Even the most earnest  advocates of the drinking-water theory
must admit that the theory is by no  means proved, in the  sense
in which a mathematical proposition may be proved, and it  cer-
tainly cannot be asserted that the drinking water is the only
means by which the zymotic diseases may be propagated ;  the
coincidences, however, if coincidences they be, are most remark-
able, and every year  adds  to their  number.  To choose  a  single
example from the  multitude which are  accessible, we may take
the case of an outbreak of typhoid fever in North Boston, Erie
Co., N.  Y., which occurred in the year 1843, consequently before
the connection between typhoid  and drinking water had become
a theory.  The community consisted  of nine families (forty-three
persons), and typhoid fever had never been known in the vicinity
until in  the year  named a sick traveler took lodging at the tavern,
and  twenty-eight days thereafter died of what  was pronounced
by the physicians to be typhoid fever.  The disease spread, twen-
ty-eight persons  in all  were  attacked, and only three families es-
caped.  These three  families were the only ones which did not use
the well of the tavern, two of them on account of distance, and one 
DRINKING WATER AND DISEASE.
23
on account of a feud between  them and the inn-keeper.  The
latter family lived within four rods of the tavern.  The physi-
cians, at that time, ascribed the  communication of the disease to
a " contagium contained in the emanations from  the body," but
the people charged the family referred to with poisoning the well,
so marked was the  coincidence.   Subsequently, Dr.  Flint,  in
reviewing the case, regards it as  " vastly probable, if not certain,"
that the disease was communicated  by the  drinking water, the
source of which was so situated that it  must, in all probability,
have been contaminated by the  dejections of the first patient.*
   Many other instances might  be cited where a number of fam-
ilies or persons using the same well or other source  of water
supply  have become victims to the disease,  which does not,  at
the time, appear elsewhere; there are many  instances where the
closing of the suspected source of supply has at once put a stop
to the  further spread of the disease;  there are  also instances
where people have assembled in  numbers on account of some
celebration, and sickness has followed in the  case of a  large pro-
portion of those who have used  a certain water, while the others
have  not been affected;  latterly  there  have been  cases where
sickness has broken out among families obtaining their milk from
the same source, and investigation has shown that impure water
was used in the dairy.   The most weighty criticism urged against
the acceptance of the theory which, in such cases as those men-
tioned,  regards the water as the cause of disease,  is that, in the
investigations made,  sufficient  attention has not been  paid  to
other  features of the circumstances and  surroundings which
might, with equal likelihood, be  factors in the production of dis-
ease.   No doubt, in  some instances this  criticism is just; but if
we  rule out all cases where the observations are  manifestly im-
perfect  there still remain instances enough to make the connec-
tion between the water drank  and the disease  contracted ex-
tremely probable.  As this is a matter which, in the present state
of science, cannot be  absolutely proved or disproved, the duty
of those who  have to advise or to decide in matters relating  to
water supply is perfectly clear;  it is to err on the side of safety,
to admit the hypothesis that specific diseases may be conveyed

  * Austin Flint, M.D.  Reports and Papers Am. Public  Health Assoc, i, pp. 164-
172. 
24
WATER  SUPPLY.
by the drinking water, and to guard all sources of  domestic and
public supply from the possibility of contamination by the dejec-
tions  of persons sick with zymotic diseases and by excremental
matter generally.
   What has hitherto been said has had reference, to the pollu-
tion of water by excremental matter from  persons actually sick
with communicable  diseases.   Any pollution,  however, by ex
cremental matter should be  guarded  against, partly because at
some  time the discharges of sick persons  may accompany the
other excremental matter, and  partly because there is evidence
that under certain circumstances  the  discharges of healthy per-
sons and animal matter generally may give rise to disease.  Under
what  circumstances excremental  matter becomes  dangerous we
do not know.  It is certain that it is often taken into the stom-
achs of men and animals, apparently without  doing any harm.
Fish often gather about the mouths of sewers and seem to thrive ;
the Norwegians save up in summer the dung of the horses and
sheep to serve as food for the cattle in winter ;  and in many
localities where wood is scarce, dried  animal excrement  is used
for fuel and in direct  contact with the food to be  cooked.  Dr.
Emmerich, who does not believe in the " drinking-water theory,"
himself drank dilute  sewage for a number of days  in succession,
and persuaded several of his  patients  to do likewise, with no ill
effect: * moreover, the experience of  every water-analyst shows
that there are many grossly polluted wells which have never been
known to produce disease.  It  is  thus difficult to believe that in
ordinary excremental matter  there is any specific poison; but as
there  seems to be abundance of circumstantial evidence to show
that disease does, at times, follow the  use of  water which has
received excremental  pollution, we are  forced  to  believe either
that the organic matter undergoes change, and in  certain stages
of decomposition  can produce sickness, or that it is accompanied
by something, not yet isolated, which is  the real morbific princi-
ple, or, indeed, that its effect is to predispose to disease, which
fails to attack others not thus predisposed.
   Next in importance to  excremental matters is the refuse from
slaughter-houses,  wool-pulling  establishments,  tanneries,  etc.,__
animal refuse, in  fact, from  various sources.  Here we  are met
* Zeitschrift fiir Biologie, xiv  (1878), p. 591. 
DRINKING WATER AND DISEASE.
25
by the objection that much animal matter is consumed in a more
or  less decayed condition with apparent harmlessness,  as  for
instance, ripe game or ripe cheese: but, to offset this, there are
numerous cases on record where sickness has arisen from spoiled
meat, especially in the form of sausages and potted meats.  But,
after all, as stated above,  the evidence which  connects disease
with polluted water is purely circumstantial, and the  amount of
organic matter, even in waters classed as dangerous, is so small,
that, as pointed out by Professor Mallet,* it furnishes " important
evidence against any chemical theory of  the production of dis-
ease from this source, any theory based on the simple assumption
that some of the  chemical products  of  the decomposition of
organic matter are poisonous or noxious in their effect upon the
human system."  Instancing two particular waters, he says :  " If
the whole of the organic carbon and nitrogen found in such waters
as  Nos. 35 and 36, of the highly dangerous character of  which
there can scarcely be a  doubt, existed as  strychnine, it would be
necessary to drink about a half a gallon of the  water  at once in
order to swallow an average medicinal dose of  the alkaloid.  It
is not easy to believe that the ptomaines,  or any other chemical
products of the putrefactive change as yet observed, can possess
an intensity of  toxic power so  very much greater than that of
the most energetic of recognized poisons.  While numerous facts
go to  support the belief that, not to  the  effect of any chemical
substances (such effect necessarily standing in definite relation to
their quantity), but to the presence of living organisms, with their
power of practically unlimited self-multiplication, we must in all
probability look for an  explanation of most, at  any rate, of  the
mischief  attributable to drinking water, it  is of course  possible
that indirectly a large amount of organic matter in water may be
more dangerous than a smaller quantity, as furnishing on a greater
scale the suitable material and conditions for the development of
noxious as well as harmless organisms."
   Although there are many substances of vegetable origin which
are violent poisons, such as the vegetable alkaloids, for example,
it is generally held  that  refuse of vegetable origin is of much less
importance as a source of pollution than that coming from animal
sources.  This  is probably true, in  general, but  it  is well known

            * National Board of Health Bulletin, May 27,  1882. 
26
WATER  SUPPLY.
that the vegetable refuse from certain manufacturing operations
may be very  offensive:  such, for instance, is the  refuse from
starch  factories,  the  water in which flax  has  been retted,  etc.
That such water would  be unfit  to  drink, unless enormously
diluted, one can hardly doubt.  To quote again from Professor
Mallet:
   " If the theory be accepted, which has so much in its favor,
attributing the production of disease by organic matter in drink-
ing water not to any specifically poisonous substance or substances,
but to  the presence and action of living organisms, it seems quite
conceivable that a water  containing organic matter of any kind,
including  vegetable matter, may  be harmless  at one time,  and
harmful at another, when perhaps a different stage of fermenta-
tion or putrefactive  change may have been entered upon,  and
special organisms may have made their appearance or  entered
upon a new phase of existence.  Thus, there  might possibly be
safety  in  drinking a peaty water, or water filtered  through beds
of dead forest leaves, when fresh ;  danger when, after a certain
amount of atmospheric exposure, bacterial  organisms had become
developed; and  safety again, perhaps, after the growth of such
organisms had fallen off, and more or less of the available organic
matter had been consumed."
   However views may differ as to the possible injury from  this
or that particular form of contamination, we are safe in accepting
the two following principles as  fundamental guides in the selec-
tion of a water for water  supply :
   I. A water suitable for domestic supply must be free  from all
substances which are known to produce an  injurious effect on the
human system, or which  are  suspected with good  reason, or on
good authority, to produce such an effect.
   2. The water should  be, as far as practicable, free from all
substances and from all  associations  which offend the  general
aesthetic  sense of the community,  and thus affect the  system
through the imagination,  even if there is good  reason to  suppose
that it  is  in itself perfectly harmless.
   The first of these principles needs  no argument to justify it;
with reference to the second, a word  or two may be said.  Dr.
Emmerich, even, admits  that not every one could  drink dilute
sewage as he did, because the mere idea of so doing, or the sight
of a floating hair or other unattractive object, would no doubt 
DRINKING WATER AND DISEASE.             27
 with many persons produce disgust and nausea, and, if the water
 were forced down, it would most likely  be thrown  up again.
 While there is no doubt of this power of the imagination and its
 effect on the physical  system, common sense must fix a limit to
 the application of this second principle, and some latitude must
 be allowed according to the circumstances  of the particular case.
 Thus, if a lake is chosen as the most  available  source of supply,
 the fact that some persons bathe in its waters can hardly condemn
 it for use; and the fact that a limited amount  of town drainage
 finds its way into a stream does not necessarily prevent its being
 used at some  portion  of its  course, although a stream once seri-
 ously polluted should not be looked  upon as an available source
 of supply.  Again, most persons naturally  object to water  as
 muddy as that of many of our Western streams, in spite of the
 favorable testimony of those in the  habit of using it, but by a
 short residence in St. Louis,  for instance, most persons soon be-
 come accustomed to the turbidity. The turbidity is a real objec-
 tion to the water, but,  in the case  of a water like  that  of the
 Missouri, a town would not be justified in postponing the intro-
 duction of the water because it was not able at the same time to
 adopt a scheme for its thorough filtration.  In the same way, if
 the only objection to a river or pond  water is a yellow or brown-
 ish-yellow color derived from vegetable, especially peaty matter,
 the water need not be condemned, although most persons would
 prefer a colorless water.
   Undoubtedly, the best water for drinking is a moderately soft
 spring water, in which all possibility  of contamination is out  of
 the question.   Unfortunately, however, it is comparatively sel-
 dom that such water is available  in  quantities sufficient for the
 supply  of large towns.  Many spring waters are  so hard that,
 while not unsuited  for drinking, they  are unsuited for many man-
 ufacturing uses, for use in steam boilers, for washing and culinary
 purposes.  It  is a mistake to claim that the water which is abso-
lutely best for drinking must be chosen, at any expense, as a town
 supply ; when a soft surface water, free from appreciable pollution
 can be obtained, it entails a very serious and constant expense to
reject it in favor of a hard water, which may, to  be sure, be clearer
to the eye and somewhat more pleasant to the taste.  There are
surface waters and there are surface-water supplies which are un-
doubtedly bad, but a good surface water, such as  may be taken 
28
WATER  SUPPLY.
directly from many streams or such as may be obtained from deep
lakes and from proper storage basins, is perfectly well suited for
domestic use or for town supply.  There are some who maintain
an  opinion  contrary  to  that which  has been expressed.  The
Vienna Commission in 1864, rejected  surface waters from among
the waters suitable for domestic use, on the ground of their vari-
able temperature (see page 91) and  their liability to pollution.
The German Public Health Association, at the Danzig meeting
in 1880, by a small majority and after  a lively discussion, adopted
a resolution to the effect that spring water  or properly protected
ground water were the only admissible sources of supply; but two
years later this dictum was modified so as to include filtered river
water as  fulfilling the required conditions,  and this conclusion is
sanctioned by practice and experience. 
CHAPTER  II.
                   WATER  ANALYSIS.

    It is not the purpose of the present chapter to give in detail
all  the  various methods employed in the analysis of water, or to
serve as a guide to those wishing to make such analyses.  Ex-
cellent  manuals on this subject already exist.  An attempt will
be made, however, to explain what is the meaning of the various
terms used in the reports of water analysis, and to  indicate the
significance to be attached to the figures given.
    For this discussion we may classify the substances occurring
in a natural water according to the following scheme:
    I. Suspended matter......j g^g™0'  ( Animal.
                                " ( Vegetable.
    2-Disso,ved ma,,er.......I lar-.... j *—•  , Animal.
                                 {  s       ( Vegetable.
    Suspended matter.—The  determination of the  amount of sus-
pended matter is principally of value with reference to possible
schemes of sedimentation  or  filtration.  The  operation is com-
monly conducted by passing a measured quantity of water through
a paper filter which has previously been dried at ioo° C. and then
weighed;  after the passage of the water, the filter with its con-
tents is again dried at ioo° and weighed  for the second time.
The difference between the two weights  is the weight  of the
suspended matter.  The filter with  its contents is then  trans-
ferred to a platinum crucible, and the crucible is heated until the
filter has  been  burned up  and the organic matter destroyed.
The weight of what remains, minus the weight of the ash which
a filter,  such as was used, is known to leave, is  the weight of the
inorganic or mineral portion of the suspended  matter.  Another
method, which is exact  enough for  most  purposes, consists  in
evaporating a measured quantity of the water  in its natural con-
dition, and an equal quantity which  has been filtered through
paper.  The  residues in the two cases are weighed and the dif-
ference  is approximately the weight of the matter which was  in
suspension.                    i 
30
WATER  SUPPLY.
    It is quite as important to know the character of the suspended
matter as to know its absolute amount.   It is desirable to know
whether it settles readily, and, if it contains much organic matter,
whether  this is mainly of animal or of vegetable  origin.   Some
information as to the latter point may be obtained by observing
the appearance and odor when it is strongly heated, but micro-
scopical examination is of the greatest service in this connection.
    In expressing in figures the results of the analysis, a consid-
erable difference exists in the practice of different chemists as to
the unit  to  be  employed.  The methods of expression in most
common  use are the following:
    (i) In grains  to  the  English (imperial) gallon, which  meas-
ures 277 cubic inches and is equivalent to 10 lbs., or 70,000 grains,
of pure water.  This method is still quite common in England.
    (2) In grains to the U. S. gallon, which measures 231  cubic
inches and is equivalent to 58,372 + grains of pure water.  This
method is very common  in the United States.
    (3) On a decimal basis, as so many parts (by  weight) in  1,000,
10,000, 100,000, or 1,000,000 parts of  the water  according to the
amount of dissolved matter present.  Thus, mineral waters are
usually reported as containing so many parts in 1,000 or in 10,000
parts, while  for potable waters parts in 100,000  or  1,000,000 are
employed.  The preference of the author is decidedly for " parts
in 100,000,"  which is now generally used in France and Germany;
also in the Reports of the Rivers Pollution Commission of  Great
Britain, and, in this country, in the reports of the National  and
of many State Boards of Health.
    (4) As so many milligrams to the liter.  This would be equiv-
alent  to  so  many parts  in 1,000,000 if the water possessed  the
same density as pure water;  that is,  if a liter of the water actually
weighed 1,000 grams.   Practically, the error introduced by  meas-
uring instead of weighing the water taken for analysis, is, in  the
case of most potable waters, less than the error of analysis, thus:
If the specific grav-ity is	So many milligrams to the liter	Equal so many parts in 1,000,000.	Diff.
1.010	5.000	4-950	O.050
I. OIO	IO.OOO	9.901	0.099
I.020	5.000	4.902	O.098
I.020*	IO.OOO	9.804	O.196
I.040	5.000	4.808	O.192
I.040	IO.OOO	9.615	0.385
* The specific gravity of sea water is about 1.029. 
WATER  ANALYSIS.
31
    In the case  of mineral waters, sea-water, etc., the difference
 is too great to be neglected; and, in such cases, it should always
 be distinctly  stated whether the results are in milligrams to the
 liter, or in parts in 1,000,000 by weight.
    Dissolved  substances.—Gases.—Almost  all  gases dissolve  in
 water to a greater or less extent.  It is seldom, however, that a
 water which is proposed or used as  a source of supply contains
 appreciable quantities  of any gases  other than those of the
 atmosphere—oxygen, nitrogen, and carbonic acid.  These gases
 are present in very varying proportions.  Oxygen is found  in
 all waters which have been exposed to the air.  The waters  of
 artesian wells often  contain none of this gas, but they absorb it
 at once on reaching  the air; waters from highly polluted sources
 are also  deficient in  oxygen.   Nitrogen occurs to  a greater  or
 less extent in all waters, and in some mineral  or effervescent
 waters it forms the largest part of the dissolved gases.  Carbonic
 acid is present in all  potable waters; its presence is  of important
 influence in determining the amount of carbonate of lime which
 a  given water can contain, and the solvent effect  of water on
 many minerals is due to the presence of carbonic acid.
    It was formerly the general custom to make a complete quan-
 titative analysis  of the various gases present in a sample of water
 under examination.   The analysis was made by boiling out the
 gases from a measured quantity of water and submitting the
 mixture  obtained to the  accurate but tedious methods  of gas
 analysis.  When, however, as often happened, the determinations
 were not  made on the spot, but,  on  the contrary, on samples  of
 water which had been standing for days or for weeks, they were
 nearly worthless, and are  now rarely made except in the case of
 mineral waters.   In  fact,  at the present time, it  is seldom  that
 the amount of any dissolved gas  is determined, except  oxygen;
 and for determining the amount of  oxygen in a given water, a
 process was devised  a  few years ago  by Schutzenberger which
 admits of being  performed with sufficient accuracy  out of doors.
A water which is polluted by  decaying organic matter not only
 calls upon the air about it to furnish oxygen for the combustion
of the decaying matter, but uses  up  in the process  more or less,
sometimes all, of the oxygen  previously dissolved  in the water.
The amount of dissolved  oxygen is thus considered by some to
be  an indication, in the  inverse direction of  course, of the 
32
WATER  SUPPLY.
amount of impurity present.   An  example of the application of
this method may be found on page6i.  The results thus ob-
tained are of value, as in this  case, in tracing the course of the
same polluted stream, but a knowledge of the absolute amount
of dissolved oxygen gives no means of judging of the purity of a
single  sample of water; for, not only is the water of some arte-
sian wells free from  oxygen,  as stated above, but the ground
water  generally  and the water of  unpolluted springs and  deep
wells is also deficient in oxygen.
    In the case of all the gases, the amount present is indicated
as so many cubic inches to the gallon, or as so many cubic centi-
meters to the liter.
    Total solids in solution.—The  determination of  the  total
amount of dissolved  matter  is made by evaporating a measured
quantity of  water to dryness in a weighed platinum dish, drying
at some definite temperature, and then weighing the dish with its
contents.  The determination is, at  the best, a rough one, and
the solid matter obtained by evaporation does not exactly repre-
sent what was originally in solution.  In the  evaporation  some
substances pass off with the steam and are lost.  Other substan-
ces are changed in character by the treatment.  If the residue be
dried at the temperature of boiling water, which is that most com-
monly employed, some of the salts retain water of crystalliza-
tion ; at a somewhat higher temperature, even as low as 1400 C,
the organic substances begin to be decomposed and lose weight.
In spite of this, some chemists use a temperature as high as 1800 C.
It is generally of no importance for sanitary purposes that the de-
termination  should be exact, for it is of no consequence whether
a water leaves 4 or 6 parts  of  " total solid residue," whether it
leaves  10 or 12 parts, but in the case of periodical  examinations
of the same water the determinations should be made in the  same
way at all times, in order that  they may be compared with each
other.
   It is seldom  necessary for  sanitary purposes to  make a com-
plete analysis of the water and to determine the amount of each
of the various compounds which make up the "total solids."  A
few of the mineral constituents are almost always determined for
special reasons, and, in individual cases, others may be estimated,
but, as a rule, the indications  of qualitative tests suffice.   In a
water which has passed through metal pipes, or which receives 
WATER ANALYSIS.
33
 the flow from mines, or from manufacturing operations, poison-
 ous metals should be looked for; lead and copper are the most
 common, and less than one-tenth of a grain of lead to the gallon
 has been known to do harm; arsenic is frequently  found in run-
 ning  streams and sometimes in water which contains, or rather
 which deposits, oxide of iron, but the amount is usually too small
 to notice; arsenic has, however, been the cause of well-pollution
 in the neighborhood of manufactories of aniline colors.
   Chlorine.—Chlorine is almost always determined quantitatively.
 It will be understood that this element never occurs free in nat-
 ural waters, but always in combination as chloride of sodium or as.
 some other chloride.   The amount is generally reported as so much
 chlorine, although some analysts  prefer to calculate the corre-
 sponding amount of chloride of sodium (common salt), and report
 in this way.  Although  chlorides are present in all  soils and nat-
 ural waters, the quantity in the uncontaminated water of  most
 regions is  very small.  Where this is known to be the case, the
 presence of any noticeable amount of chlorine  (say much more
 than  I part  in  100,000) indicates  contamination  from  human
 sources, as chloride of sodium is a constant constituent of sewage
 and of animal refuse in general, and is not eliminated to any con-
 siderable extent either in passing through the soil or by the action
 of vegetation.  Chlorides remain as evidences of past contami-
 nation after  all  other evidences have  ceased  to exist, although
 the amount present does not bear any constant proportion to the
 amount of polluting substances which  are  or have been in the
 water.
   Hardness.—A determination of the " hardness " usually finds
 a place in the examination  of a water proposed as a  source of
 supply.  The determination is made by taking advantage of one
 of the properties which make hard water undesirable—namely, the
 property of destroying soap.  A solution of soap is prepared of
 such a strength that a measured quantity of it is exactly destroyed
 or neutralized by a  known  amount of some compound of  lime.
 The lime compound is previously dissolved  in a certain amount,
 say 100 cubic centimeters, of water, and the test is made by ascer-
 taining how much of this same standard soap solution is destroyed
 by 100 c.c. of this particular water.  The hardness of another
portion of  the water  is determined after boiling for some time;
this is called "permanent hardness" and  is due  to sulphates
           3 
34
WATER  SUPPLY.
 and other soluble compounds  of lime and magnesia.  The total
 hardness, less the permanent hardness, is the " temporary hardness"
 and is due to  the bicarbonates of lime and magnesia, which are
 decomposed by boiling.  The hardness is generally expressed in
 degrees, which have different significations in different countries.
 In England, where the process originated, a degree of hardness
 corresponds to a grain of carbonate of lime in one imperial gallon
 of water; for example, a water of  5 degrees hardness means  a
 water, each gallon of which contains compounds of lime or mag-
 nesia or both equivalent  in soap-destroying power to 5  grains of
 carbonate of lime.  In Germany the degrees of hardness indicate
 the equivalent of so many parts of  oxide of calcium (quicklime)
 in 100,000 parts of water.  In France the degrees mean so  many
 parts of carbonate of lime in 100,000 parts of water.   In America,
 in spite of  the anomaly, many express the hardness in  English
 degrees, i. e., in grains to the imperial gallon, while the other re-
 sults are  given in  grains to the  United States gallon.  The
 French system of parts in 100,000 is, however, to be preferred.
    Combined nitrogen.—Nitrogen exists in potable waters under
 a variety of forms of combination.  Animal matter generally con-
 tains nitrogen, as do also many substances of vegetable origin:
 this is usually spoken of as " organic nitrogen."  Nitrogen also
 exists in the form of ammonia and  ammoniacal salts, and  these
 compounds are due almost entirely to the decomposition of nitrog-
 enous vegetable and more especially animal matters.   For this
 reason, although in itself harmless,  the  ammonia is determined
 quantitatively.   The amount present, even in a polluted water, is
 small, and when expressed in figures—as in the various tables on
 following pages—seems insignificant, nevertheless, as a sign  of or-
 ganic pollution, its determination should not be omitted. Although
 the amount of ammonia is so small—a water containing 0.1 part
 by weight in 100,000 parts  of the water being grossly polluted—
the figures are entitled to confidence because the method usually
 employed is very delicate, and, by  a process of distillation, the
 ammonia in a large volume of  water may  be concentrated into a
 small bulk.   The " Nessler test," which is employed in estimating
ammonia, is capable of detecting 1 part by weight of ammonia in
20,000,000 parts of water.
   A great  diversity of opinion exists as to the value which at-
taches to a determination of the exact amount of nitrogen pres- 
WATER ANALYSIS.
35
ent as nitrites and nitrates.  The compounds themselves, in small
amounts, are no  doubt harmless, but it is also true that they re-
sult from the oxidation of nitrogenous organic matter.   The
nitrifying process is now believed  to  take  place  under the in-
fluence of minute organisms, and the process goes on in the vari-
ous soils at very different rates according to the alkalinity of the
soil, to the amount of moisture and to other conditions.  More-
over, the nitrates once formed may again be reduced to ammoni-
acal compounds,  or  even to free nitrogen,  so that  the nitrates
cannot be a quantitative indication of the amount  of pollution.
    In  spite of this, Frankland lays great stress on the exact deter-
mination of nitrogen in this form, and has introduced into water
reports the term  " previous  sewage  contamination."  The figures
given, in any case, under this head are reached by determining
the total amount of nitrogen which is present as ammonia, and
also as nitrites and nitrates; after  subtracting the small amount
of nitrogen which rain water contains in these forms, there  is
calculated from the remainder how  much of what is called " aver-
age  London sewage" would be necessary to account for this
amount of nitrogen.   The composition of the so-called " average
London  sewage" is not, as might be supposed,  deduced from
a considerable number of examinations  made at  various  times,
but the average sewage is taken arbitrarily as containing 10 parts
of combined nitrogen in 100,000 parts.
    Mallet (in a report already cited) is " inclined to attach spe-
cial and very great importance to a careful determination of the
nitrites and nitrates  in water to be used for drinking."
    It  is true that in consecutive examinations of the same water
it is satisfactory to know exactly the amount of nitrates and the
variation from time to time; but, in case of a single examination,
it is generally sufficient to know whether there is much or little,
or none.   The test  most commonly applied, although not the
most delicate, is the  sulphate of iron (ferrous sulphate) test.  A
small quantity of the water under examination is mixed  in a
glass tube with an equal volume  of pure concentrated  sulphuric
acid.   The mixture, which  becomes very hot, is  cooled to the
temperature of the air, and  there is then poured upon it a solu-
tion of sulphate of iron.  If nitrates are present, a dark ring or
layer forms between the two liquids.  The amount of nitrates
present may be  inferred from the extent  to which the water 
36
WATER  SUPPLY.
must be concentrated before it will give indications by this test,
but the indications are strictly comparable only when the test is
performed in precisely the same way and by the same person.
   It should be understood that  the argument drawn from the
presence of  nitrates is this:  The nitrates indicate the previous
existence of nitrogenous organic matter, which has been oxidized
and converted  into  harmless compounds by natural agencies.
If these same agencies could be relied on indefinitely it would be
well, but no one can tell at what moment—owing to increase in
the amount of  the polluting substances, or to their gradual accu-
mulation in  the soil, or to other changed conditions—the natural
agencies may prove inadequate to the task and  allow  incom-
pletely oxidized and harmful substances to reach the source of
supply.
   Organic  matter.—Of the polluting  material which reaches
water which may be  used for drinking, the organic  portion is felt
to be that which directly or indirectly introduces the element of
danger. Just how and from what particular substances the dan-
ger arises  is unknown, and it is  extremely doubtful whether the
dangerous something will ever be an object  of chemical deter-
mination, but in our present ignorance it is generally felt that
it is desirable to obtain such indications as  are possible of the
amount and character of the organic matter present.
   To  a person unfamiliar with chemistry, it might seem to be
no difficult task to determine exactly how much matter of animal
and how much  matter of vegetable origin is present in a given
water.  The truth is, however, that it is not only difficult  but
impossible, either to  determine the total amount of organic mat-
ter or to  decide upon its origin.   As far as the total amount is
concerned, the  fact that it cannot be determined is a matter of
no great consequence.  Even if the chemist  could say with cer-
tainty that a particular water contained exactly I or 2 or 5 parts
of organic matter in 100,000, we should be far from having the
data necessary to form an opinion as to the wholesomeness of the
water, for  it is  evident to any one  that a pound of sugar or of
glycerine would have a very different importance from that of  a
pound  of (dry)  faeces, yet either is a pound of organic matter.
   Formerly it was the general custom to subject the residue of
evaporation (" total dissolved solids ") to the action of a low red
heat until all the carbonaceous matter was destroyed and to deter- 
                       WATER ANALYSIS.                     37

mine the loss  of  weight.   Thus was obtained what is now gen-
erally tabulated as  " loss  on ignition," or " organic and  volatile
matter; " but the loss of weight is far from being entirely due to
the  destruction  of organic  matter.   According to the degree
of heat applied and the length of time during which  it is con-
tinued, there is more  or  less loss due  to the volatilization  of
alkaline  chlorides.  There is  also loss from  the decomposition
and  partial volatilization  of several  compounds ; thus, the car-
bonates of lime and magnesia are more or less  completely con-
verted into oxides  by expulsion of  the  carbonic acid, or in the
presence of a sufficient quantity of silicic  acid, into silicates.   The
nitrates are converted into  carbonates, oxides, or silicates, chlo-
ride  of  magnesium is decomposed in the presence of  hydrated
compounds with escape of  chlorhydric acid, and other changes
take place which it  is not  necessary to particularize.
   For these  reasons, no two persons are likely to obtain the
same result from the same water, and not much value is attached
nowadays to the determination ; it is sometimes of  assistance in
forming the final opinion in  case of a doubtful water, but the way
in which the  residue  acts when heated  gives more information
than a knowledge of the loss of  weight.
   Of the more modern  methods in  somewhat general  use for
reaching information about the organic matter in water,  there
are three Avhich may be mentioned here, and which will be spoken
of as the " permanganate " method, the " ammonia " process, and
" Frankland's " method.*   All of the processes possess a certain
value, and all are  widely open to criticism.
   Permanganate of  potash is  a highly colored crystalline salt
soluble in water, to which, even if the solution be very dilute, it
communicates a  marked  pink  color.  This  compound, which
contains  a considerable   proportion of oxygen, possesses the
property of oxidizing, with more or less readiness, most forms  of
organic  matter, being itself  destroyed in the  process and losing
the characteristic  color.   By successive  additions of a perman-
   * These various processes will be discussed only briefly in this, place.  They
have recently been thoroughly investigated by Professor J. W. Mallet, under direc-
tion of the National Board of Health.  The full report has not yet appeared, but a
preliminary report was published as a Supplement (No. 19) to the National Board of
Health Bulletin, May 27, 1882. 
38
WATER SUPPLY.
ganate  solution of known  strength  until  the color  persists,  it
is possible to determine how  much  permanganate is destroyed
by a  known volume of  a given water.  There are various ways
of applying the permanganate solution.  Some prefer to use the
reagent in alkaline, and  others in acid solutions; some heat the
liquid to  one temperature  and some to another.*  The results
obtained are reported by stating how many parts, by weight, of
the crystallized permanganate are required for 100,000 parts by
weight of water; or how many parts,  by weight, of oxygen (from
the permanganate) are  used  up in the process.   Some, indeed,
assume  an arbitrary number, by which they multiply the amount
of permanganate employed, and call the result organic matter.
Where  the expression " organic matter" occurs in German re-
ports, the figures  are  probably obtained  by multiplying the
amount of oxygen used  up by 20, f but in American  reports the
expression is quite likely to mean simply the " loss on ignition."
The results of the permanganate method cannot have an absolute
value, because different organic substances vary in the complete-
ness with which they are oxidized under the same conditions;
and, even  if they were  all completely  oxidized  under certain
attainable conditions, it would still be true that one gram of one
kind of  organic matter would require a very different amount of
oxygen  from that which  would be required by one gram of some
other kind of organic matter.   Moreover, with the same water,
the results differ very much according to the method  of employ-
ing the  test, so that to be able to give a useful interpretation to
any particular results, it  is  necessary to know what method was
followed by the analyst.
   The  so-called ammonia method of water analysis was devised
by the  English chemists Chapman,  Wanklyn and Smith, \ and
has been much  used  in  England and  in this country.  In this
   * See Kubel's Anleitung zur Untersuchung von Wasser, bearbeitet von Dr. Ferd.
Tiemann, Braunschweig, 1874. Also a paper by Dr. Tidy, Chemical News, xxxvii
(1878), p. 283.
   f Or by multiplying the amount of permanganate consumed by 5.  This is accord-
ing to Dr. Woods, but Dr. Letheby prefers to multiply the amount of permanganate
by 8.  Whatever number be used, it  frequently happens that the "organic matter,"
as thus estimated, exceeds the weight  of the " total dissolved solids."
   % Water Analysis.  By J. A. Wanklyn and E. T. Chapman.  5th edition,
rewritten by J. A. Wanklyn, London, 1879. 
WATER ANALYSIS.
39
method, advantage is taken of the fact that certain kinds of ni-
trogenous organic matter, when treated with a strongly alkaline
solution of permanganate of potash, give off a definite portion or
the whole of their nitrogen as ammonia; and the value of the
method lies in the assumption that it is the nitrogenized organic
matter which is  to be regarded as the  chief source of danger in
polluted water.   In working  the ammonia method, the water
under examination is put into a  retort, made alkaline by means
of carbonate of  soda, and distilled as long as the water which
condenses contains enough ammonia to be measured by Nessler's
solution.  Then a solution of caustic soda and permanganate of
potash is added, and distillation is continued.   Another portion
of ammonia now comes off, owing to the action of  the perman-
ganate  on  the  nitrogenous  organic  matter.   The  amount  of
ammonia thus obtained is determined, and is tabulated as "al-
buminoid ammonia,"  because albumin is one of the bodies which
acts in this way.
    It will  thus  be understood that the  so-called "albuminoid
ammonia"  is not something which exists in the water ready
formed ; moreover, because different amounts are obtained  from
the  same weight of different  nitrogenous substances, as well as
on account  of the fact already alluded to, that the  oxidation of
different substances by the permanganate  of potash is more or
less  incomplete, the figures obtained have a relative rather than
an absolute significance.
   Although this method does not  accomplish all that might be
desired, the results, properly interpreted, are of great value, and
the method has been  of immense service in the cause  of public
health.
   The third method, known as the " combustion " process, or
Frankland's method, was devised by Frankland and Armstrong.
and  used  by the Rivers  Pollution Commission of Great  Britain
in the examination of the very large number of waters, the anal-
yses of which appear in the various reports of  the Commission.
This method is by far the most elaborate of any that have been
proposed:  it  consists in evaporating a given quantity of the
water, under carefully regulated conditions, and in submitting
"the  residue to a process of organic  analysis, by which all the
carbon is converted into carbonic acid and the nitrogen is  liber-
ated in  the gaseous state. The mixture of nitrogen and carbonic 
40
WATER  SUPPLY.
acid is then' analyzed by processes of gas analysis.  The results
are stated in so many parts of "organic carbon " and so much
" organic nitrogen," in 100,000 parts of the water, and sometimes
the sum of the two is spoken of as the amount of the " organic
elements."  The character of the organic matter is inferred from
the relative proportion of carbon and nitrogen.
   The process, as Frankland himself says, is " both troublesome
and tedious."   The apparatus  employed is frangible  and some-
what costly, and the  manipulative skill of a trained  chemist is
required to carry out  the work.  It is moreover a process that
cannot be taken up off-hand, even by a trained chemist, but one
requiring  tolerably constant practice.  As Mallet says: " It is
better  adapted to  regular use .in  the  examination  of  many
samples of water in a large public laboratory than to  occasional
use by a private individual in now and  then examining a single
water."
   Although the combustion process is the most elaborate, and,
in some respects the most satisfactory that we have,  even this,
"in its present  form  cannot be considered as 'determining' the
carbon and nitrogen of the organic matter in water in a sense to
justify the claim of ' absolute ' value for its results which has
been denied to  those of  all other methods.  It is but a method
of approximation, involving sundry errors, and in part a balance
of errors." *
   Standards of purity.—Having followed this brief description
of the methods of analysis most frequently employed, a person,
who is not a chemist, may naturally ask  for some directions in
order to interpret the figures reported by the analyst.  Now, it
is true that it  may be  possible  to  fix certain numerical  limits
and  to  reject  without hesitation all  waters  exceeding  these
limits; but there  always will be difficulty in deciding how near
to any limit a suspicious water  may come and  still be used with
a reasonable degree of safety.   To condemn  a water without
sufficient cause is, of course, undesirable, as the procuring a dif-
ferent supply may involve considerable expense.
   Moreover, it cannot be insisted upon too strongly that  differ-
ent classes of water cannot be judged by the same standard, and
  * For a full discussion of the sources of error, see Mallet's report, already alluded
to ; also, Amer. Chem. Journ., iv (1883). 
WATER ANALYSIS.
41
the results of the analysis of waters belonging to different classes
ought not to be put into the same table or otherwise arranged so
as to invite comparison.  If within the same geological area it is
possible to analyze the water from a considerable number of un-
polluted wells,  a standard may be fixed for the well water of that
region, and a surface water may be compared with other surface
waters of the same or of a similarly situated region ; or a stream in
one part of its course may be compared with its own unpolluted
head  waters.   To fix, however, a definite standard  which will
apply to all waters and by which  any one can judge of  a given
water  from the numerical  results of analysis is impracticable.
Every doubtful  water  must be considered  by itself with all the
light  that can be brought to bear upon it.
   Bearing in mind what has just been said, we may note the in-
terpretation which is  given to the  results of  the several methods
in common use for determining  " organic  matter," or, at least,
for obtaining indications as to its amount and character.   Wan-
klyn's own interpretation of the results of the ammonia process
is essentially as follows:
   If a water yield no " albuminoid ammonia," it may be passed
as organically pure, despite  of much free ammonia and chlorides;
a water giving  less than 0.005 part of " albuminoid  ammonia "
in 100,000 parts may be regarded as very pure.  A water contain-
ing 0.005 part  of "albuminoid  ammonia"  together with a con-
siderable  quantity of free ammonia is  suspicious,  but in  the
absence of free ammonia, the  "albuminoid ammonia"  maybe
allowed to amount to something  like 0.010 part; above  0.010
should be regarded as very suspicious, and according  to Wanklyn
over 0.015 part  should condemn the water.
   The Rivers  Pollution Commission, in  interpreting the results
of Frankland's  process, make the following classification :  " Sur-
face water or river water which contains in 100,000 parts more
than 0.2 part of organic carbon or 0.03 part of organic nitrogen
is not desirable for domestic supply, and ought, whenever practi-
cable, to be rejected.   Spring and deep-well water ought not to
contain in 100,000 parts more than 0.1 part of organic carbon or
0.03 part of organic nitrogen."
   Dr. Frankland, while " deprecating a  hard and  fast  division
of water into classes," suggests a  rough classification according
to the amount  of organic carbon present; this classification is 
42
WATER SUPPLY.
given in Table III, the  figures indicating such a fraction of  one
part by weight of organic carbon in  100,000  parts by weight of
the water.
   Dr. Tidy, while admitting the impossibility of deciding of the
quality of a water from an incomplete analysis suggests certain
limits as a guide to the  interpretation of the results obtained by
the permanganate process, conducted, be it understood, accord-
ing to a particular method.  These also appear in Table III.

          TABLE III.—Classification of Natural Waters.
                         Parts in 100,000.
Classification.	Organic ' Dr. Fra Upland sur-face water.	Zarbon.— NKLAND. Other waters.	Oxygen required to oxi-dize Organic Matter.— Dr. Tidy.
I Water of great organic purity .	O. -0.2 O.2-O.4 O.4-0.6 0.6 +	O.-O.I O.I-0.2 O.2-0.4 0.4 +	O. -O.05 O.05-O.15 O.15-O.21 0.21 +
			
   Some of the limiting amounts which have been suggested by
other chemists are given in Table IV :
TABLE IV.—Standards of Purity.
         Parts in ioc.ooo.
	Total Solids.	Organic Matter.	Nitric Acid (N,0,). 0.4 O.5-I.5 O.5-2. 2-7	Chlorine.	Total Hardness.
	50 50 50 50	2. 5-5-4-		0.2-O.8 2-3 3-5 3-5	18 18-20 18-20 17
Kubel and Tiemann .... Wibel.................					
					
					
   Professor Mallet, in the report already alluded to, after record-
ing the  results of an examination into the various processes of
analysis which have been briefly described, draws certain  general
conclusions as follows:
   "1. It is not possible  to decide absolutely upon the whole-
someness or unwholesomeness  of a  drinking water by the mere
use of any  of the processes examined for the estimation of
organic matter, or its constituents.
   " 2.  I would  even  go further, and say that, in judging the
sanitary  character of a water, not only must  such processes be
used  in connection with the investigation of other evidence of a 
WATER  ANALYSIS.
43
 more general sort, as to the source and history of the water, but
 should even be deemed of secondary importance in weighing the
 reasons for  accepting or rejecting a water not manifestly unfit
 for drinking on other grounds.
    " 3. There are no sound grounds on which to establish such
 general ' standards  of  purity'  as have been proposed, looking
 to exact amounts of organic carbon or nitrogen,  'albuminoid
 ammonia,' oxygen of permanganate consumed,  etc., as permis-
 sible or not.  Distinctions  drawn  by  the application of such
 standards are arbitrary, and may be misleading.
    " 4. Two entirely legitimate directions seem to be open for
 the useful examination by chemical means of  the organic con-
 stituents of drinking water,  namely, first, the  detection of very
 gross pollution, such  as the contamination of the  water of a well
 by accidental bursting or crushing of soil-pipes, extensive leakage
 of drains, etc., and  secondly, the periodical examination of  a
 water supply,  as  of  a  great city, in order that,  the  normal or
 usual character of the water having been previously ascertained,
 any suspicious changes  which from time to time may occur shall
 be promptly detected and their cause investigated.
   " 5. In connection with this latter application of water  analy-
 sis, there seems to be no  objection to the establishment of local
 'standards of purity' for drinking water, based  on  sufficiently
 thorough  examination  of the  water supply in  its  usual con-
 dition."
   These conclusions are given, as they coincide  almost exactly
 with  what the author has frequently had occasion to  assert, and
 has for years tried to teach.  " In the majority of cases, chemical
 examination alone cannot be  relied upon  as  giving conclusive
 evidence as to the suitability of a water for drinking.  Of course,
 if a water is  hard, the chemist can say, without hesitation, that
 the water is unsuited  for supply on account of its probable effect
 on steam boilers, and because it will  be  uneconomical for  use in
 washing.  If the water contains arsenic or lead  or other poison-
 ous metal, the  chemist  can discover it.  If the water is grossly
 polluted, or is of exceptional purity,  chemical  examination can
 determine  these facts ;  but,  in  a vast majority of cases, while
 chemistry may teach  something and aid in the decision, it cannot
teach everything,  and it  cannot  decide.   Now, it  would be very
convenient, if it were possible, to take each item which is  made 
44
WATER  SUPPLY.
the object of analytical determination, and say that a good water
may contain  so  much, and if a water contains more, it is  not
good.  This  is impossible: a certain amount of  the  same sub-
stance might in one case be a sign of fearful contamination, while
in another  it  might indicate  only  a normal constituent of  the
water.
   " In view of the impossibility of saying exactly what is and
what is not harmful, any considerable departure from the  normal
character of the water in a given locality should be regarded with
suspicion.  It is true that various students of the matter of water
supply have  formulated 'standards' which a water  may  not
overpass.   They are, however, only of relative value." *
   It should  not be inferred that  the chemical analysis is value-
less because it cannot furnish data for absolute  decision, but it is
a great mistake  to suppose  that  the  proper way to  consult a
chemist is to send a sample of water in a sealed  vessel with no
hint as to its source.  On the contrary, the chemist should know
as much as possible as to the history and source of the water, and
if possible should take the samples himself—that is if he is to ex-
press an opinion as to the suitableness of the water for  drinking.
Nor is it sufficient that some other competent  person  should
possess the knowledge of the locality, etc., and endeavor to in-
terpret the figures furnished by the chemist.   There  are many
things which  guide the chemist that he cannot put into  numer-
ical results or even on to  paper at all.   Many observations  are
made in the course of an analysis by an experienced  person, of
which he is himself hardly conscious, but which aid in making up
the final opinion.  Foxf very truly says:
   " It is a golden rule in water analysis never to give an opinion
unless the analyst knows (i) the nature of the source of a water—
whether it comes from a spring or well or river or rain reservoir,
etc.; (2) the  depth of the well, if it is withdrawn  from  one ; (3)
the geology of the district from which it is derived, together with
the character of the soil and  subsoil ; (4) the  distance  from the
source of the water of the nearest filth or drain."
   At the present time,  chemical  examination,  in connection
with a thorough knowledge of a proposed source of supply, must
* Buck's Hygiene, Vol. i, p. 303.
f Sanitary Examination of Water, Air and Food.  London, 1878. 
WATER ANALYSIS.
45
 be the main guide in the selection or rejection of a water;  but
 there is reason to hope that  eventually the  decision may be
 thrown largely upon the biologist. Investigations have been made
 from a biological stand-point in two directions: (i) by an exam-
 ination  of  the organisms in the water itself  or which  develop in
 it when the water is allowed to stand; (2) by injecting the concen-
 trated water, or a solution  of  the residue of evaporation, under
 the skin of rabbits or other animals, and observing the effect on
 the temperature, etc., of  the animals experimented upon.
    With reference to  the first method, it may be  said  that a
 microscopical examination of  the  suspended and sedimentary
 matter should always accompany the chemical examination,  and
 there  is no difficulty in  recognizing  grains of starch, fibers of
 cotton,  silk,  wool, etc., and  many other sorts of animal  and
 vegetable debris if present; of course, substances like those men-
 tioned are evidence of more or less contamination.  With regard
 to living organisms, we do not know as much as we have a right
 to hope to  know about their connection with the wholesomeness
 of a water.   It may be said, in a general way, that bacteria occur-
 ring in considerable numbers are a  sign of impure water, as are
 also certain infusoria, such as paramecium, vorticella, monas,  etc.
 The occurrence of leptothrix, crenothrix, etc., are also suspicious
 signs, but the diatoms and the green algae, as a rule, do not indi-
 cate impurity, and are, generally speaking, harmless unless suffi-
 cient numbers are present to affect the water by their death and
 decay.   (See also  Chapter IV.—Surface water as a source of
 supply.)
   The second method of biological investigation was proposed
 by Emmerich,*  who says:  " If the water under examination, or
 the aqueous extract (of the residue), to the bulk of 40-80 c.c. be in-
 jected subcutaneously into a full-grown rabbit, and fail to produce
 a continued elevation of temperature of more than I9 C, followed
 by death, then the water contains no  putrid substances  dangerous
 to health, or contains them  in so small an amount that they  are
 not worth considering."   He further suggests, that the amount
of such dangerous substances may be estimated from the amount
of water which must be evaporated in order to obtain  an extract
which will produce in animals the effects which he describes.
* Zeitschrift fur Biologie, xiv (1878), 563-603, 
46
WATER SUPPLY.
   Something has been done in this same direction by Dr. George
M. Sternberg, U. S. A., * in connection with his investigation of
malarial fever, and also by Prof. H. Newell Martin, of the Johns
Hopkins  University, in  connection with  Prof. Mallet's  investi-
gation into the different methods for the analysis of drinking
waters.  Whatever may  develop in the future  from this method
of research, it is certain  that it has not yet become a method on
which we can rely, and that Emmerich's statement is altogether
too sweeping.
   In this connection  should  also be mentioned the proposal by
Koch f to examine the water by  means of culture experiments
in gelatine with subsequent microscopic examination; but this
method, like the preceding, is at present simply developing.   A
somewhat similar method of experimenting has, for a longer time,
been occasionally  employed.   It consists  in carefully collecting
some of the water in flasks that have previously been sterilized
by heat and introducing a small quantity  into  each  of  several
test-tubes containing some freshly boiled  Pasteur's solution, so-
called.  This solution is  particularly  favorable to the growth of
" bacteria," if any such  or their germs are in the water.  The
tubes are  plugged with  cotton-wool, and an attempt is made to
estimate the amount of impurity in the water from the degree of
turbidity produced in a given time.   None  of these methods have
yet reached the  stage of  practical utility, and it  must be left  en-
tirely with the specialists to interpret  the results of  their own
observations.
   Popular tests.—The writer has little sympathy with popular
tests.  It  is  true that the observations on odor and  taste and
color may be made by a  person who  is not a chemist ;  there  are
also certain qualitative tests that any intelligent person can learn
to make  satisfactorily, and which would serve as indications  to
the chemist.  It is, in general, true  of popular tests, that they
are apt to lead either to  an unjustified sense of security or to  an
unnecessary  feeling of alarm.  The following test  for  sewage
contamination, proposed  by Heisch, and recommended by others,
has some value :
   Put some of the water—say half a pint—into a clean, colorless,

   * Supp. No. 14,  Bulletin National Board of Health, July 23, 1881.
   f  Mittheilungen aus dem kaiserlichen Gesundheitsamte.  I Band, Berlin, 1881,
page 36. See also a paper by Angus Smith, in The Sanitary Record, February, 1882. 
                      WATER ANALYSIS.                   47

glass-stoppered bottle, add  a few grains  of  white  sugar, shake
until the sugar has dissolved, and leave the bottle freely exposed
to the light  in a warm  room for a week or ten days.   If the
water becomes turbid, it  is open to suspicion of sewage contam-
ination ;  if it remains clear it is probably safe.
   Collection of samples.—In connection with  the chemical exam-
ination of water, the importance of taking due care in the collec-
tion of samples may be alluded to. The best  vessel for collecting
water for analysis is a glass-stoppered bottle  ; a clean demijohn
which has  never been  used  for any other purpose and  which is
stopped  with  a new and  clean cork answers perfectly well  and
is often  more  convenient.  Tin cans or stoneware jugs are  not
suitable.
   Considerable care is necessary in order  to get a fair sample of
the water.  The demijohn should be rinsed  several times thor-
oughly with the water to be collected and finally filled not quite
to the mouth.  The cork should be washed with the same water
and the  demijohn  stoppered tightly.   The  stopper should be
tied over with a piece of cloth or " bandage gum," and the string
sealed with sealing wax, that the water  may not be tampered
with in transit.
   If the water is taken from a pump or from  a  faucet, enough
water should  be  pumped or allowed  to  run to  waste  to thor-
oughly clear  the pipes.  In taking water  from a pond  or river
it will generally be most convenient  to  use a  clean crockery
pitcher, which  may be filled by plunging it beneath the surface
(so as to  avoid any scum or floating material) and then  emptied
into  the  demijohn; or  a new and clean tin dipper  may be
employed.  If a glass bottle is used,  it  may be plunged directly
into the water and thus filled.  In taking water from a river, the
middle of  the stream should be chosen  if only one sample  is
taken. 
CHAPTER  III.
           RAIN WATER AS A SOURCE OF SUPPLY.

   The collection of the rain directly as a source of public sup-
ply, in our latitude, would be undertaken only under very excep-
tional circumstances.  In many localities, however, where there
is  no sufficient public  supply and  where wells are out  of  the
question,  the  collection of  rain water  by the individual house-
holder becomes a necessity ; also in cases where the public supply
is hard and unfit for washing.  A house covering an area of 40 bv
20 feet, or 800 square feet, would receive upon its roof, with a
rainfall of 42 inches, 2,800 cubic feet of water  in  the  course of
the year.   If  three-quarters of this could be collected, it would
furnish a  supply of something over 40 gallons per day, on  the
average.
   The rain which falls, even in  the  open country, is far from
being pure in  the chemical  sense,  as it washes from the air both
gaseous and solid substances.   The Rivers Pollution Commission
of Great Britain obtained the following average results from the
examination of 73  samples of rain water, all but two of which
were collected at the experimental farm of  Messrs. Lawes and
Gilbert, Rothamsted, England:

       Total dissolved solids................... 3.95 parts in 100,000.
       Organic carbon........................ 0.099
       Organic nitrogen....................... 0.022
       Ammonia............................. 0.050
       Nitrogen  as nitrites and nitrates..........0.007
       Total combined nitrogen................ 0.071
       Chlorine............................... o. 63

   In  manufacturing localities, the air, and consequently  the
rain, may  contain much impurity; and, in any event,  when  the
rain  is collected near habitations the  impurity is considerable.
The  excrement of birds, the dead bodies of  insects, leaves from
the trees,  and  various sorts of dust and dirt lodge on the roofs
and are washed  off,  mainly by the first portions of the rain. 
             RAIN WATER AS A SOURCE OF SUPPLY.         49

 Devices, some of them automatic, have been invented, by which
 the first portions of the rain are allowed to go to wa<;te, but they
 have not come into general use.   Besides the sources of impurity
 to which rain water is naturally and unavoidably liable, there are
 accidental sources of contamination: thus,  instances have been
 known where servants have  emptied the house slops from  the
 upper stories on to the roof, thence to find their way into  the
 cisterns.  It is to  be hoped that such  instances  as this  are ex-
 tremely rare.
    The  proper storage of rain water is as  important as its col-
 lection.   For the  storage of water  in  small quantity there is
 nothing better, from a sanitary point of view,  than slate tanks;
 iron tanks protected  from rusting by  a coating of coal-tar paint
 are also  unobjectionable.  Tanks situated  at  the top  of  the
 house are sometimes in direct communication with  the drains
 by means of the overflow pipes, and  in  some cases it has been
 thought that the water  has been rendered impure and injurious
 to  health by gases from the  soil-pipes.   Any mode of construc-
 tion which  admits the  possibility of  such communication  is
 faulty.   Rain water is  generally stored  in underground cisterns
 built of brick and cement, and acquires a slight hardness by
 dissolving lime  from the cement, especially when the cistern is
 new.  The  overflows from such cisterns should be constructed
 so as to preclude all possibility of contamination from the liquids
 or gases of drains or sewers.  In some localities wood is used
 for the  construction of  the rain-water  tanks;  thus in New
 Orleans, according to  Dr. Smart,* the cisterns are constructed
 of cypress wood,  and vary in capacity from 500 to 60,000 gallons-
 " The usual capacity of the dwelling-house  cistern is  about  two
 thousand gallons.   They are  raised a few feet from the ground,
 and their contents  are  protected  by a lid or cover.   Some  are
 placed under the  shade of a  balcony ; a few have a special roof
 over them ;  but the majority have only such protection from the
rays of the sun as is afforded by their position against the house
wall.  Many, especially in the older parts of the city, are situated
in unventilated inclosures which  are rank with  the emanations
from unclean privies."
  * Report on  the Water Supply of New  Orleans and Mobile.  Bull. National
Board of Health, April 17, 1880.
4 
50
WATER  SUPPLY.
   On account of the sediment which accumulates in the cisterns
in which  rain water is  stored, it is  desirable  that such cisterns
should be thoroughly cleansed from time to time, and that the
water should be  filtered before  being used for drinking or for
culinary purposes.  The matter  of filtration will be discussed in
a subsequent chapter (page 151).   Dr. Smart examined a number
of cisterns in New Orleans which had not been cleaned in many
years, and found  that the rate  of deposit  was, on the average,
about  an inch a year.   After a few days' repose, the sediment
carried in by the rain has settled to the bottom and  the water
has become clear,  " but every  succeeding rainfall not only in-
creases the quantity of this sediment, but, by its  inflow, stirs up
that which has already accumulated, rendering the water impure
until sedimentation  is again  accomplished.  As time passes the
sediment increases, and the water becomes unfit  for use after
each rainfall.  These conditions are aggravated in the dry season,
when the water  is low in the cistern  and the quantity of  sedi-
ment is relatively much increased."
   Underground cisterns, being out of sight  and  consequently
too often out of  mind,  are not  only liable to be  neglected and
allowed to go uncleaned for a long  time, but are  also liable to
become leaky and thus to allow of the contamination of the
water by soakage from the soil.   Dr. Smart, in his investigation
of the water supply of Memphis, examined a considerable  num-
ber of the 4,000 cisterns said to be in use.  He found—

        Undoubtedly sound.................................. 163
        Probably sound......................................  82
        Probably siping.....................................  94
        Undoubtedly leaky................................... 190
               Total number examined...................... 529

               Examination of Cistern Water.

   It is often very difficult to decide, by chemical examination,
whether  a cistern water is to be regarded as fit to drink or not.
Gross pollution can  be  easily detected, but, as  the presence of
more or  less organic matter is a necessary consequence  of the
mode  of  collecting  the water, it is impossible to  say just how
much is permissible, and where  the line should be drawn.   The
most  valuable indications are afforded  by the chlorine, which 
RAIN WATER AS  A SOURCE  OF  SUPPLY.          51
should be present only  in trifling quantity, as a  rule, not  over
0.5 part in 100,000, except near the sea.  The total solids should
not much exceed 4 or 5 parts  in  100,000, but a larger amount is
sometimes due simply to the solvent  action of the water on the
cement lining of the cistern.  Dr. Smart considers cistern waters
containing from 0.010 to  0.020 part  of albuminoid ammonia in
100,000 as usable, and regards those containing over 0.020 part as
dangerous, but as much as 0.010 ought  to awaken suspicion and
give rise to inquiry.   The following table contains the results of
the examination of a number of cistern waters in various localities.
TABLE V.—Examination of Cistern Waters.

      [Results  expressed in Parts in 100,000.]
Locality
Oakham,  Eng.
Epsom, Eng......
Goring, Eng......
Podehole, Eng. ...
Sheffield Barracks..
Boston, Mass.....
Same, filtered*...
Another .........
Same, filtered *...
Another..........
Same, filtered *....
Wilmington, N. C.
Another..........
Another..........
Cincinnati, O......
Another..........
Another..........
Another..........
Another..........
11.70
 8.10
 9.42
 5-28
12.00
 5.28
 6.56
 3-24
 4.80
 3-48
 5.20
 5-05
 6.90
 3 60
 2.68
 4.72
 4.48
 7.96
 4.10
0.005
0.009
0.032
0.
0.130
0.013
0.012
0.005
0.024
0.021
0.007
0.002
0.016
0.005
0.004
0275
0.027
0.004
0.020
►J s
0.008
0.007
O.OII
0.016
0.007
0.007
0.015
0.008
0.008
0.123
0.055
0.118
0.016
0.360
O
0331
0.167
0.215
0.142
0.154
o
0.090
0.021
0.061
0.029
0.053
Authority.
 I. IO Riv. Poll. Com.f
 O.go   "   "   "
 O.80
 0.90 I  "   "   "
 I.60   "   "   "
 O.32
 O.36
 O.IO
 O.I2
 O.69
 O.7O
 O.70
 O.52
 O.52

 0-55
 2.76
 I.97
trace
trace
W. R. Nichols \
C. W. Dabneyg
C. R.  Stuntz
The table might  be extended indefinitely, but the  results  have
little real significance except in connection with a minute knowl-
edge of the history of the various samples.
    While rain  water, on account  of its softness,  is peculiarly
* These cisterns were provided with a brick filtering-wall.
f Sixth Report, p. 29.
X Filtration of Potable Water, p. 83.
§ Report North Carolina Agricultural Experiment Station, 1S81, p. 158.
(Report of Water Department, Cincinnati, 1880, p. 80. 
52
WATER  SUPPLY.
adapted to use in washing and in cooking, it is also wholesome
as a beverage if collected  so as to be  reasonably pure.  There
has, however, long been an opinion that  snow water is unwhole-
some.  Dr.  Charles Brewer, U. S. A., says that  " mountaineers
(in the West), to whose long observation and experience in the
wilds some  attention is due, attribute the origin  of the so-called
mountain fever to the melting of snows and the drinking of snow
water."  Dr. Smart * quotes facts to show that  this suspicion is
well grounded, and says that " snow water, therefore, pure  as it
seems, must not be accepted as innocent until its freedom from
organic ammonia in deleterious or suspicious quantity  has been
proved."  This applies especially to snow melting and flowing in
the mountain streams.   As collected with the rain and  stored in
cisterns it is wholesome, as far as we know.   (Compare  p. ioo).

               NATURAL AND ARTIFICIAL ICE.

   As the rain is water which has been more or  less completely
purified by a natural process of distillation and condensation, so
ice is water which has been more  or less completely purified by
another natural process—that of crystallization.   It is, therefore,
not inappropriate to consider ice in this connection.
   The great  extent to which ice is used  in  many parts of the
United  States makes  its  purity a  matter of very considerable
importance. The surface water supplies,  even of Northern cities,
become heated in summer so that, to cool the  water, at  least
half its own weight of ice is needed, and very much more  than
this is often used in practice.
   When ice forms in or on a body of  water, the bulk  of which
remains  unfrozen,  it   is generally  supposed  that  foreign  sub-
stances are excluded and  that  the  ice itself is essentially pure.
It is true that foreign, especially saline,  substances are  excluded
to a large extent,  but  the ice always retains more or  less, and,
if the water contains organic impurities, the ice will contain them
also.  In fact, a pond  or river which is not fit for a water supply
on account of present evident contamination should  not be  used
as a source of ice supply.   It is also, unfortunately, the  case that
ice is often cut in winter on shallow ponds which for a  consider-
* Buck's Hygiene, ii, p. 133. 
DANGERS OF IMPURE  ICE.
53
 able  portion  of the year have no existence  or  exist merely as
 stagnant pools.  That such ice should be wholesome, ought not
 to be expected, and there are well authenticated  cases on record
 where sickness has arisen from the use of impure ice.  Such a case
 of well-marked character occurred in  1875 at Rye Beach, N. H.*
 The ice had been cut on a brackish stagnant pond into which a
 small brook brought  a  quantity  of saw-dust  from  several saw-
 mills.  Here,  the trouble was ascribed to the presence of decom-
 posing organic matter.   That, in some cases, the germs (if they be
 germs)  of specific diseases  might  retain their  vitality  even if
 frozen into the ice, we can but regard as possible from what we
 know of the endurance of the spores of the lower algae ;  at any
 rate, ice should not be cut on contaminated waters.
    It is unfortunately true that when public  attention is  called
 to a possible, but hitherto little noticed cause of disease, exag-
 gerated  statements  are  sure  to  be  disseminated  through the
 public prints  and otherwise—statements which  have a basis  of
 truth, but which are so  presented as, oftentimes, to awaken un-
 necessary  anxiety and alarm.   The  statement—"The old idea
 that  water purifies itself  by freezing is now pretty generally
 abandoned "—is true, if it means that water does not thus purify
 itself completely; it is untrue as  far as it naturally leads to the
 inference that  water, in  freezing,  does not purify  itself  at all.
 Further, the author believes  that the following  statements (in
 which the  italics  are his), even if  hereafter proved true, are cer-
 tainly premature, and  have  not  been proved by experiments
 hitherto published.  " The even  more dangerous  organic im-
 purities resulting from human and  other animal waste are retained
 in ice unchanged as regards both quality and quantity, the latter
 indeed being likely to  be  increased!'  " The  germs of infectious
 disease  .   .   .   are retained in ice unaffected, and from  their
 comparative lightness are so concentrated therein as  to number that
 they exist  in even greater  quantity than  in  the same amount of
 water, under similar circumstances, at other seasons of the year." f
    Large quantities of artificial ice are now  made in the United
 States, and in a number  of Southern cities the artificial product

    * See a paper by A. II. Nichols, M. D., in the Seventh Report of the Mass. State
Board of Health, 1876, p. 465.
    f The Dangers of Impure Ice in The Sanitarian for May, 1882.  See also a paper on
Impure Ice, in the Fifth Annual Report of the Connecticut State Board of Health, 1883. 
;4                    WATER  SUPPLY.

has driven the natural ice from the  market.  With some of the
machines, distilled water alone is frozen ;  with others, ordinary
well or other water.   Ice machines, on a  small scale, are used
also in hotels for freezing carafes, etc.  Particular care should be
used with reference to the water  employed in  making artificial
ice, because  the water is frozen  solid, and whatever is dissolved or
suspended in the water must remain in the ice.  In one machine,
however (Beath's patent), the ice is formed by causing water to
flow over  pipes through which  the freezing agent flows.   Only a
part of the water used is actually  frozen  as it flows over the
pipes  or the continually increasing thickness of ice, and the bulk
of the impurities, dissolved or suspended, flows away.

                Chemical Examination of Ice.
   The standard  of purity  for ice should be placed  very high.
Ice should contain very little dissolved matter, next to no chlo-
rine, and the "albuminoid ammonia" should not exceed 0.005
part in 100,000.  Great care must  be exercised in  preparing the
sample for analysis, because the ice  in melting attracts organic
impurities from the air.
   In fact, one method which  has been proposed for examining
the air for organic matter, consists in employing a glass  funnel
drawn to a point and filled with fragments of ice.*  The moisture
in the air condenses   as dew  upon the outside of the  funnel,
                 trickles down  into the  vessel below, and the
                 water thus collected is  examined for organic
                 matter in various  ways.   For this reason, also,
                 the fact that the drip from refrigerators often
                 becomes offensive when allowed to stand  in a
                 warm room, does not show  necessarily that
                 the ice used  was impure.
                     In melting ice for analysis, a fair specimen
                 cake should be selected  and broken into frag-
                 ments in  a clean place.   The fragments may
                 then be placed in  a wide-mouthed bottle cov-
                 ered with a  plate of glass, and, when enough
                 of  the ice has melted  to have  washed itself,
   * Smee : Social Science Transactions, 1875, p. 486.  The figure is from Fox's
Sanitary Examination of Water, etc.
 
CHEMICAL  EXAMINATION OF ICE.
55
this portion of water  should be poured away, and the remainder,
after melting, be subjected to analysis.  Or the fragments may
be  placed in a large funnel covered with a plate of glass until 5
or 10 per cent has melted, and the remainder be then transferred
to the wide-mouthed  bottle without touching the ice with the
hands.  Since even the best of ice is liable to have bits of organic
substances frozen  into it here and there, the  " albuminoid  am-
monia "  should be determined also in the water which has  been
filtered  through paper.  It must  also  be remembered  that the
ice which is sold for family use  often is partly " snow ice,"  and
that the snow, in falling, always brings down ammonia  from the
atmosphere.   Table  VI  contains the results  of  a  number of
chemical examinations of ice  from various sources.

              TABLE VI.—Examination of (Melted) Ice.
                     [Results expressed in Parts in 100,000.]
Description.
Rye Beach, N. H.  Supposed cause of sickness
Same, filtered through paper...................
Boston Ice Company, 1875......................
Fresh Pond, near Boston, 1878.................
Spy Pond,   "    "    " .................
Little Spy Pond, near Boston, 1878............
Horn Pond,     "   "   1876*............
Hammond's Pond, "   "   1877.............
Jamaica Pond Ice Co., 1877.....................
Another sample of same___ ..................
Pittsfield, Mass., 1876.........................
Same, filtered through paper...................
en		q
		
		
O 1/5	<	5 < Z 5
	2	3 0
< H O	S s	<<
H	<	
13-52	0.0208	0.0704
9.72	0.0213	0.0165
0.76	0.004s	
5.00	0.0060	0.007s
5.00	0.0064	0.0064
2.50	0.0060	O.OIIO
9.2	0.0026	0.0440
2.4	0.0066	0.0190
0.8	0.0180	0.0160
1.2	0.0260	0.0160
i-5'	0.0072	0.0061
0.44	0.0077	0.0013
Authority.
0.3
0.3
W. R. Nichols.

S. P. Sharpies.

 E. S. Wood.


W. R. Nichols.
    * The large amount of impurity in this case was probably due to some local and
accidental cause :  this ice was thought to cause sickness. 
CHAPTER IV.
         SURFACE WATERS AS SOURCES OF SUPPLY.

   THE character of  the water which  flows in the streams and
is stored  in the lakes  and ponds  of  any region depends largely
upon the geological character of the country.  Where impervious
rocky strata predominate, the water flows off from the surface
readily, and the streams carry water free from any very consider-
able amount  of dissolved substances: where the water  soaks
quickly into the ground and the  streams and lakes are fed by
springs, or, at least, by water which has passed for some distance
underground, the amount of dissolved matter becomes more con-
siderable.  As a rule,  the  surface waters contain less  dissolved
matter and are softer than the well waters (ground water) of the
same region;  on the  other  hand, they generally contain  more
organic matter  of animal  and vegetable origin, they are  often
colored, they are  liable to  be turbid or to become so at time of
flood, and are, in several respects,  more subject to variation than
the ground water.
   While  much that  might be said with  reference to surface
waters will apply both to running  streams and to ponded waters,
it will  be  convenient  to divide the subject, discussing first the
matters of turbidity and  pollution, which  are peculiarly  felt  in
the case of rivers, and subsequently discussing  the  difficulties
arising from variable temperature  and from animal and vegetable
growths, which are felt peculiarly  in the case of ponded waters.

                     Turbidity of Streams.

    It is hardly necessary to dwell upon the fact that rivers are
frequently objectionable as sources of supply, on account  of the
large  amount of suspended matter,  mainly clay,  which many
of them  carry  invariably and others at time of flood.   Some-
thing  will be  said   of this  matter in  connection  with sedi-
mentation in Chapter VIII:  at  present,  it  will suffice  to call 
THE POLLUTION OF  STREAMS.
57
attention  to Table VII  (made up  from  statements in Geikie's
Text-book of  Geology) which shows the amount of suspended
matter in various  rivers, and also shows that the  amount varier
very much in the same stream under different circumstances.


    TABLE VII.—Amount of Suspended Matter in Various Rivers.
River.
Rhone....
Rhone....



Rhine.....





Maas......


Danube...
Vistula—
Po.........
Durance...

Ganges...

Irrawaddy.

Mississippi
Date.
1844.
Locality and Condition.
Dec. 1849
1862-1871
Lycns.......................
Aries, low water...............
  " flood...................
  " maximum...............
  " mean..................
Strasburg, July and Aug.......
Bonn...........................
Bonn..........................
Bonn, after dry weather......
Uerdingen, after sudden floods
In Holland.....................
Maximum......................
Minimum.....................,
Mean............... ..........
Mean..........................
Maximum......................

In flood........................,
Mean.......................
In flood.................. .....
Yearly mean..................
In flood.......................
Low water....................
Mean.........................
  Suspended
   Matter
 Expressed in
Parts in 100,000.
  by     by
weight, volume, w'g't
  5
  14.29
 434-78
2,222.22
  50.00
  2.00

  20.50

  I'73
  78.00

  47.61
  1.40
  IO.O">
  32-68
2,083.33
 100.03

 233-95
 196.08
  58.82

  17-47
  66.6
 Parts of
Water for
 1 part of I
Sediment. Authority.
6.25
  17.20
2,083.00
 333-00
116.82
 97-94


 34.48
by	by	
wg't.	vol.	
17,000		
7,000		
230		
4?		
2,000		
50,000	. Daubree.	
	16,-00 Horner.	
4,878	.. . iBischof.	
57,800	"	
1,282	.... IStiefensand.	
	100 Hartsoeker.	
2,100	.... iChandellon.	
71,420	....	
10,000		
3,060	5,814 Hartley. 48 Spitieli.	
		
	300 Lombardini.	
48	___ iPayen.	
1,000		
4~8	856 Everest.	
5io	1,021	
1,700	___ [Login.	
5i725	... |	
1,500	2,900 Humphreys	
		and Abbot.
                    The  Pollution  of Streams.

    Owing  to facilities for  transportation, to available  water-
power, and also to the  opportunities furnished for the discharge
of  waste  material,  running streams  naturally attract  to their
banks manufactories and  towns,  and,  in turn, become  polluted
by their refuse.
    In a thickly  settled manufacturing country  like  England,
where, moreover, the streams are comparatively small, the pollu-
tion may become very serious.  In  Great Britain the matter  has
been the subject  of thorough  investigation by two Royal Com-
missions, appointed respectively  in 1865 and 1868, "to inquire
into the best means of preventing the  pollution of rivers."
    The statement  of the  Commissioners with reference  to  the
Aire and Calder, although  it has been frequently quoted, has not
Lost in emphasis: 
58
WATER  SUPPLY.
   " The rivers Aire and Calder and their  tributaries are abused
by passing into them hundreds of thousands of tons per annum
of ashes,  slag  and cinders  from  steam-boilers, furnaces, iron-
works and domestic fires; by their being  made the receptacle,
to a vast extent,  of  broken pottery and worn-out utensils of
metal,  refuse brick from  brick-yards  and old  buildings, earth,
stone and clay from  quarries and excavations, road-scrapings,
street-sweepings, etc.;  by spent dye-woods and other solids used
in the treatment of worsteds and woollens; by hundreds of car-
casses of animals,  as dogs, cats, pigs, etc., which are allowed  to
float on the surface of the streams or putrefy on their banks;
and by the flowing in, to  the amount  of  very many millions of
gallons per day, of water poisoned, corrupted, and clogged by
refuse  from  mines, chemical works, dyeing, scouring and fulling
worsted and woollen stuffs, skin-cleaning and tanning, slaughter-
house garbage,  and the sewage of towns and houses."
   " Bradford is an ancient town situated on a  ' beck ' about four
miles south of the  river Aire, into which the water of this beck
falls.  It is the center of the worsted district."  The Commis-
sioners allude to the increase of  population and to the increased
pollution  from dye-works, from soap-suds, and from refuse of
various kinds produced in manufactures.  " The whole of  the
sewage of Bradford, and of the populous district above the town,
flows into the  beck, producing  an indescribable state of pollu-
tion.  It has become a Yorkshire proverb of comparison for any
foul stream, to  say of  it that it is as polluted as Bradford  Beck.
At  the time of our inquiry Bradford Beck was the source of
supply of the  Bradford  Canal, the fluid of which became so cor-
rupt in summer that  large volumes  of inflammable gases were
given off, and, although  it has usually been considered an impos-
sible feat ' to set the River Thames on fire,' it was found practi-
cable to set the Bradford  Canal  on fire, as this at times formed
part of the amusement of boys  in  the  neighborhood.  They
struck a match placed on  the end  of  a stick,  reached over, and
set the canal on fire, the flames rising six  feet  high and running
along the surface of the water for many yards like a will-o'-the
wisp; canal boats have been so enveloped in flame as  to frighten
persons on board."
  The river Irwell, near its source, " is of excellent  quality for
all domestic purposes."   It flows, however, through the midst of 
THE POLLUTION  OF STREAMS.
59
 a manufacturing district, and finally passes through Manchester
 before  it empties into the Mersey.  At  Manchester the  slug-
 gishly flowing stream is black as ink, and it is there joined by the
 Irk and Medlock, streams not less polluted than itself.
    Of the Clyde, the following are bits of evidence :
    "At one time the Clyde was comparatively pure and limpid—
 salmon fishing within the precincts of  the harbor being very pro-
 ductive.  Now,  through Glasgow downwards, but diminishing
 below the mouth of the Cart, it is very foul and turbid ;  in short
 a gigantic open sewer, noxious  gases  being continually evolved,
 which,  during summer, are  so overpowering as to force the bulk
 of the passenger traffic from the river  to the rail."
    " The harbor is more like a gigantic cesspool than a harbor in
 the proper acceptation of the term."
    " In summer time there is a perfect commotion with air and
 gas bubbles over the whole surface of the water, and it is so bad
 that we cannot use  it for the  boilers of the  little steam  ferry-
 boats that ply  across the river."
    While the rivers  of Great Britain are probably polluted gen-
 erally to a greater extent than those of most other countries, the
 trouble is by no means peculiar.  In France the condition of the
 Seine below Paris has led to the appointment of several depart-
 mental and municipal commissions, and to the proposal of exten-
 sive and costly plans for disposing of the sewage of the  city.
 Other rivers of  France, as, for instance, the  Vesle, at Rheims,
 have become the receptacles of town  and  manufacturing refuse
 so as to call imperatively for restrictive action.  In Germany the
 increasing pollution  of  the sluggish  Spree by  the sewage of
 Berlin was one of the moving causes which has led to an entire
 change  of the system of sewerage, and to the attempt at purifi-
 cation and utilization of the entire sewage of the city on sewage
 farms.
    In this country, many of our streams carry such a volume of
 water that the refuse of the largest cities is soon lost; but some
 of the smaller  rivers, for a  portion of  their course at any rate,
 are rendered unfit for domestic use.  The Blackstone River, in
 Massachusetts,  receives  the sewage of Worcester and causes
 complaint from the towns and manufactories on its banks.   The
 Schuylkill and Passaic rivers are no longer fit  for water supply
where water-works now exist.   The Chicago  River was an ex- 
6o
WATER SUPPLY.
ceedingly foul stream—if stream it could be called—until it was
diverted into the Illinois River; and  other examples might  be
cited.  The contamination of the water of the Great Lakes, in
the neighborhood of cities like Cleveland, Chicago and Milwau-
kee, is a very serious matter.  There is a limit to the distance to
which tunnels can be carried into the open lake, and  the problem
of disposing of the sewage of the cities, otherwise  than by dis-
charging it into the lake, is one which will soon compel solution.
    It is not our purpose to enter into details as to the nature
and amount  of the polluting materials which are discharged by
various manufacturing industries, nor to discuss how far the indi-
vidual substances  are  injurious to plants or to fish, or  how  far
they render the water  unfit for drinking and for  other domestic
purposes.*  We may admit that  certain substances are injurious,
even  in  small  amount; but, while this is true, it  is also true
that  much  manufacturing refuse is of such  a character as to
be, except in excessive quantities, of no appreciable  influence on
the human  system. Thus, the addition to a water  of most of
the ordinary salts of  lime, soda, potash, etc., would  not produce
any deleterious effect, although the addition of lime compounds
would increase the hardness and  render the water less desirable
for washing.  Again, in  the  case of many waste liquors of offen-
sive appearance, the actual  amount  of matter  which is  really
injurious or of suspicious character is comparatively small.  Thus,
in the case of some  of the organic dyestuffs, the  weak, spent
dye-liquors, although they communicate a very foul appearance
to the water for some distance, yet contain  a comparatively small
amount of solid matter, and, if discharged into a stream of con-
siderable  size, are soon disseminated through it, and diluted to a
very great extent.
    Very  different,  however, in character and  importance,  from
much of  the refuse of  manufacturing establishments, is,  as  we
have  seen, the  sewage proper—that is, the excremental matters
from  factories and  towns—and the refuse from particular opera-
tions, such as tanning, slaughtering, rendering, wool-pulling, etc.

    * These matters are very fully discussed in the reports of the  Rivers Pollution
Commissions of Great Britain.   A brief statement with reference to the chemicals and
other materials used in various  manufacturing operations and with reference to the
liquid refuse discharged from them, is given in the Report of the Mass. State Board
of Health, 1876 : Special Report on the Pollution of Rivers by J. P. Kirkwood, C.E. 
THE POLLUTION  OF STREAMS.
61
With  our present information, too  much stress  cannot be laid
upon the importance of preventing the discharge of such refuse,
and of sewage in its more  restricted sense, into any stream or
pond used, or likely to be used, as a source of water supply.
    The importance of this matter is underrated for two reasons:
first, because of a belief that an impure and polluted water rap-
idly purifies itself by natural means ; and, second, because of the
feeling that a water  to be  prejudicial to health must be polluted
to such an extent that the animal matter may be recognized by
chemical tests.
    That a polluted water in  its flow does become purer, no one
can doubt  who has  followed the course of a polluted stream;
chemical  analysis proves the  same  thing.   There  is, however,
much difference of opinion as to  the method by which the puri-
fication takes place,  and also as to the extent to  which we may
suppose that the disease-producing something is eliminated.

           TABLE VIII.—The Seine above and below Paris.*
' Kilometers.
 31
 78
 93
log
150
242
Locality.
Corbeil (above Paris).............
Pont de la Tournelle, Paris........
Auteuil (below the city but above
  the outlets of the main sewers)...
Pont d'Asnieres (above main sewer)
Epinay (below all sewers).........
Pont de Poissy...................
Pont de Meulan..................
Mantes.........................
Vernon .........................
Rouen..........................
Organic Nitrogen. Grams per cubic meter.
O.85 I.26 0-45 O.40
  Total
 Combined
 Nitrogen.
 Grams per
cubic meter.
Dissolved
 Oxygen.
  Cubic
centimeters
 per liter.
 9-32
 8.05

 5-99
 5-34
 1.05
 6.12
 8.17
 8.96
10.40
10.42
    Table VIII contains the  results of partial examinations of
the  Seine above and below Paris.   At  Epinay, below all  the
sewers, the river is at its worst as regards the amount of nitrogen
in the form of ammoniacal salts and  organic compounds, and the
dissolved oxygen is reduced to a minimum.  After flowing some
75 or 100 kilometers, the river regains its purity as far as appear-
ance and chemical tests can indicate.
   * Assainissement de la Seine, etc, deuxieme partie, II Annexes, p. S ; also Rap-
port de MM.  Schloesing et A. Durand-Claye.  Congres international d'hygiene,
Paris, 1878, p. 314. 
WATER SUPPLY.
TABLE IX.—Self-Purification of Streams.
      [Results expressed in Parts in 100,000.]
Miles.
 5
25
 o
13J
Locality.
       Blackstone River, 1875.
North Pond, above pollution............
City Reservoir, gate-house.............
Mill Brook, below sewers...............
Blackstone River, at sash factory........
Blackstone River, at Blackstone.........

        Merrimack River, 1873.
Mean of 11 examinations above Lowell...
Mean of 12 examinations above Lawrence.
Mean of 11 examinations below Lawrence

      Merrimack River,  1879.*
Mean of 2 examinations above Lowell....
Mean of 4 examinations above Lawrence .
1°™; ' Ammonia.
Solids.
20 O.OI07
76 O.OO72
44 O.9600
04 O.0992
80 O.OO99
4.IO
4.IO
4-43
5-5Q
7-56
.0.0047
o.0044
0.0031
0.0021
0.0018
1 Albuminoid j Chlo-
 Ammonia." ! R1NE.
O.O213
O.0235
O.IIO9
O.0307
O.OI39
O.OI14
O.OIIO
0.0127
0.0132
0.0131
0.18
O.I2
3.80
O.92
O.36
0.14
0.2O
0.18
O.4O
O.44
   Table IX contains  results which are less striking  but which
point in the same direction.   The Blackstone Valley  is the seat
of considerable  manufacturing industries,  there being on the
stream and its tributaries 44 woolen mills, 27 cotton mills, 12 iron
works,  1  tannery  and  1 slaughter  house.  Some  of  the mills
cause local  pollution, but the chief source  of contamination  is
the sewage of the City of Worcester—some 2,000,000 gallons  in
24 hours—which  flows  into  Mill  Brook and  thence into the
river.
   " The water of Mill Brook, after it has received the sewage  of
Worcester,  is shown to be  very impure in this table, and on the
Blackstone  River, at  the  sash factory, about  five  miles lower
down, it still  gives unmistakable signs of  the  influence of this
pollution ; but at Blackstone, twenty-five miles below Mill Brook,
the dilution produced by numerous small streams delivering into
the main river between these  points has  all but obliterated the
evidence of impurity,  so far  as analysis can expose it, the only
marked difference  here in the  table between the water at  Black-
stone and the head water of  the river, being in the amount  of
chlorine, the increase, however, of this evidence of impurity not
being so great  as to  condemn  the  water  (by this  test) for
domestic or any  other  use.  It is  to be noted, however, that the
river  at  this  time was not at its very  low dry-weather  stage,
* E. S. Wood, M.D. 
THE POLLUTION OF STREAMS.              6$
 which usually occurs in October or November, when it occurs at
 all.  In extreme low water, the river would give greater tokens
 of impurity." *
    Of the Merrimack River it may be said that, in 1873, when
 some of the examinations were made, Lowell had a population
 of about 41,000  and Lawrence  of about  30,000;  further, at
 Lowell there are some 75 mill  buildings, in  which about 16,000
 operatives are employed.  About  10,000 horse power is derived
 from the river, and, in addition, steam power is used to the extent
 of 6,000 horse power.  The  Merrimack Manufacturing Company
 alone consumes, among other things,  7,500 gallons  of oil per
 annum,  225,000 pounds of starch, 1,100 barrels of flour, 2,500,000
 pounds of madder, 50,000 of copperas, 170,000 of alum, 200,000
 of sumac, 1,120,000 of sulphuric acid, 300,000 of bark, 350,000 of
 soda-ash, and 40,000 of soap.f
    At Lawrence there are some 25 mills (buildings), employing
 9,000 operatives.   The manufacturing  industry is  less at Law-
 rence  than at Lowell, but it  is  still  very  considerable.  The
 Pacific Mills, which is  the largest  corporation, use some 800,000
 pounds of starch, 540 barrels of flour, 8,300 gallons of oil, etc. %
    The questions naturally arise, to what causes are we to ascribe
 the disappearance of the large amount of polluting material in the
 Seine, and in the Blackstone, and why,  in the case of  the Merri-
 mack River, are we not able to trace a greater effect as produced
 by the large manufacturing cities of Lowell and Lawrence.
    In studying the self-purifying  power of streams,  let us first
 take an instance  of a substance whose course we can trace more
 easily  than that  of animal refuse, with  which we are,  of course,
 more concerned.   The following account from the First Annual
 Report of the Mass. State Board of Health, Lunacy and Charity
 (1880), will furnish the illustration :
    " On the night  of June 2, 1879, a ^re occurred in  a chemical
 works  situated on a brook whose waters eventually find theirway
 into Mystic Pond,  from which a portion of the city of Boston,
 Mass., obtains  its supply of water.  As a result of the destruc-

   * Seventh Annual Report of Mass. State Board of Health, 1876, p. 84.
   f These figures are taken from the " Statistics of Lowell Manufactures, January,
1873," published by Stone & Huse, Lowell.
   X " Statistics of Lawrence  Manufactures, January, 1872."  Published by Geo. S.
Merrill & Co., Lawrence. 
64
WATER SUPPLY.
tion by fire of the sulphuric acid chambers, a  considerable quan-
tity of sulphuric acid, estimated  at  fifty tons of  oil of vitriol,
together with salt cake and other chemicals, was washed directly
into the brook, or flowed upon the adjoining meadow-land, from
which it would slowly find its way to the stream.   Large num-
bers of fish, driven before the  acid water, or actually killed by it,
passed into the mill-ponds below and through the wheels of  the
mills.  Anxiety was felt lest the acid should reach Mystic Pond
itself; and, five days after the fire, specimens of the water were
collected for analysis.   As  far as Mystic Pond itself was con-
cerned, the fears proved groundless; but in the brook and in some
of the upper  ponds  there was an abnormal amount of dissolved
matter and especially of sulphates.  The most interesting point,
however, was with reference to the acidity of the  water.   As  a
rule, our surface  waters in Massachusetts are naturally slightly
alkaline, and, when the water is evaporated to dryness, the residue
effervesces, at  least slightly, when treated with acid.*  It was
found that even five days after the fire the water of the brook
itself and of the nearest ponds was distinctly acid.  The amount
of acid was estimated by  means of  a dilute solution  of  baryta,
using rosolic acid as an indicator.
    " The acidity  was  found to be as follows, the  results  being
expressed by  stating how many parts by weight of sulphuric acid
No.
 I
IV
VI
III
Date.
  1879
June 7,
June 7,
June 7,
June 7,
June 7,
June 8,
A.M.
A.M.
A.M.
P.M.
P.M
P.M
Locality.
From brook just below works.......................
Lower end of Richardson's Pond, about x% miles below
 works.............................. .....
Frye & Thompson's Pond, about 3 miles below works. .  .
From brook midway between Chemical Works and Rich-
 ardson's Pond, about % mile below works.........___
From canal at Mont vale, about 2% miles below works.....
Upper end of Richardson's Pond, X mile below II.......
Acidity.
	
•00	vo
	
< §	£<
0 0 a	°0
	
Eefe rt — *"	u
Oh	p.
1.74	57.500
0.74	135,000
0-37	270,000
0.18	S55.5°o
°-37	270,000
0.15	666,600
(H2S04), or its equivalent, were present in 100,000 parts by weight
of the water;  and also by stating, in round numbers, with  how
   * Whether the alkalinity is to be regarded as due in part to the presence of alka-
line carbonates, or as solely due to the presence of dissolved carbonate of calcium, is
uncertain, as there are no analyses which are sufficiently particular to determine. 
SELF-PURIFICATION OF STREAMS.
65
-many parts of water by weight one  part of sulphuric acid was
 diluted.
    " From the point numbered VI,  that is  from the canal at
 Montvale, samples were taken at intervals until the water re-
 turned to its alkaline reaction.   The  results of the examination
 were as follows :
		t.	a	rs-u	
		OJ	V	0 i>	
			"rt	<.Si	
		J3u	>	o-oO	
		So	'3	■cSOT	
Date.	Locality.	38 "o w W rt	cO — (/)	58S .2 S c	Remarks.
		"O	>-H?	t« ™ 5	
		— V	.tiffi	_ <UM	
		B'Z	•o^.	Buu	
		o"a	'3 0	O1" V"	
		H	<	H	
1879.					
June 6	Canal at Montvale	j-n.6			
	Avenue,Montvale		O. 22	4-7	
June 7		13-9	0.37		
June 9		12.8	0.26		The residue of evaporation did not f" effervesce with acid.
					
June 10		11.6	0.22		
June 13		9-4	0.16		
June 15		10.1	j Slightly j alkaline.	}'•'■	J
June 19		9.4	0.16	1.2	Residue did not effervesce.
June 30 July 8		7.7 8.4	f Slightly ( alkaline. j Slightly | alkaline.	[::::	- Residue did effervesce with acid.
    " While the water was  acid, the residue of evaporation did
 not effervesce with acid, showing that a part, at any rate, of the
 sulphuric acid was neutralized by  the  carbonates  in the water.
 It may also be noted, that  some fragments of marble were put
 into some of the water No.  IV, which had  an acidity of  0.74;
 after  standing for fifteen  hours the acidity had decreased to
 0.11, and after standing for two and a half days the  reaction was
 neutral or faintly alkaline."
    Mystic Pond is about eight miles below the works:  samples
 were taken from the upper end of the pond for several days, but
 no acid reaction was at any time perceptible.
    Thus, in the disappearance of  the  sulphuric  acid, we  have
 two actions concerned :  first, the chemical action  by which it
 was converted  probably into sulphate  of lime,  and then the
 action  of dilution, by which all traces of it were apparently lost.
 With many inorganic substances we may  predict what will hap-
pen when they come into a stream, and the  same  thing is true
           5 
66
WATER  SUPPLY.
of certain  particular  organic substances  whose  changes  have
been studied under various conditions; but of the  heterogeneous
mixture which we speak of collectively as " sewage," it would be
difficult to declare a priori what changes would take place and
what  products would  be formed.  There are, however, three
principal ways in which a natural water frees  itself from organic
pollution: (i)  by oxidation and other chemical changes; (2) by
deposition ;  (3) by dilution.
   Oxidation.—The disappearance of organic refuse is, no doubt,
to a  certain extent, due  to chemical  changes, by which the or-
ganic matter is oxidized and converted into simpler compounds;
under favorable circumstances the destruction may be complete,
the nitrogen appearing in ammoniacal compounds and nitrates,
or escaping in  the  free state, and  the carbon appearing as car-
bonic acid.  That chemical action takes  place is made evident
enough, when  the pollution is considerable, by the escape of sul-
phuretted hydrogen, marsh gas, and other gaseous products of de-
composition, as in the case of the  Bradford Beck—alluded to on
page 58.   Of the Seine, it was said in 1874 that, for the greater
part of the  year, especially in warm weather, bubbles of gas—
sometimes a meter  or a meter and  a half  in diameter—were
continually rising to the surface of the water, and the passage of
a boat caused a great  ebullition, and left a mass of foam persist-
ing for some minutes.  The chemical  change is also marked by
the partial  or total disappearance of dissolved  oxygen, as in-
stanced in Table VIII.
   Attempts have been made to reach,  by laboratory  experi-
ments, some idea of the  amount  of oxidation which may take
place  in  a running stream polluted  by sewage.   The  Rivers
Pollution  Commission mixed  urine with  water  in the propor-
tion  of  one gallon of urine to  3,077  gallons of  water.   The
mixture was agitated  from time to time,  and samples taken for
analysis.   The  results (expressed  in  parts in 100,000) were as
follows:

      Immediately after mixture, Feb.
		Organic Carbon.	Organic Nitrogen.
17,	1874	O.282	O.243
18,		O.298	O.251
19,		O.244	O.255
24.		O.225	O.253
25,		O.214	O.259
28,		O.214	O.276
 
SELF-PURIFICATION OF STREAMS.
67
   In other experiments, a stream of impure water was allowed
to flow  from one  vessel to another, freely  exposed to the air.
As a general result, the commissioners concluded that the puri-
fication due to actual oxidation had been much overrated, and
that there was no river  in the United Kingdom long enough, if
once seriously polluted, to purify itself in this way.
   Certain chemical changes, other  than  those  already alluded
to, will be  mentioned  in  the  next paragraph: we  may here
allude to  the fact that in the  destruction  of organic matter a
certain  part is, no  doubt, played by the  fish and other animal
inhabitants  of  the water, and many of the  changes which seem
to be  purely chemical appear to  be  brought about wholly or in
part by some of the lower algae  or  by those minute organisms
which are  frequently spoken of together as "bacteria."   Thus
we know there are certain  algae which reduce  the sulphates to
sulphides, and the formation  of nitrates in the soil and  in water
is ascribed also to  micro-organisms.
   Deposition.—Much waste material thrown into rivers is made
up wholly or in part of substances insoluble in water.   A portion,
and a very considerable portion, even in a running stream, is
deposited upon the bottom  or stranded upon the banks.  This
deposition can often be very plainly observed in the immediate
neighborhood of the points of discharge.  It is not, however,
suspended matters only that  are removed by deposition.   In the
first place, many substances which seem to be perfectly dissolved
are dragged out  of solution and carried down by  almost any
finely divided  substance.  This is  especially true of organic
coloring matters and of the  nitrogenous matter which gives rise
to the " albuminoid ammonia"  revealed by analysis; it is true,
but to  a very limited  degree, of some mineral salts.  In the
second place, chemical  changes take place  in the stream, espe-
cially when  refuse  liquids from  different  sources meet and mix,
which result in  the formation  of new and  insoluble substances,
and-these  when  formed  settle  out, dragging  other  substances
with  them  as just indicated.   The improvement in the  con-
dition of polluted streams which appeals to the eye is largely
due to deposition.
   The deposits,  once formed,  continue to undergo  chemical
change; they shift  their position with changing currents, and in
time  of flood may be washed  up  and,  mingling with  earthy 
68
WATER  SUPPLY.
 material held in suspension, be swept on to the sea or deposited
 in some new position, either lower down  on the stream or on
 the surface of overflowed territory.  Often, however, the character
 of the  bed of the stream becomes permanently altered  unless
 means  are taken  by  dredging  or otherwise to remove the ac-
 cumulations as they increase.
    Dilution.—Probably the most important reason of the  appar-
 ent disappearance of sewage and other waste material, is the fact
 that the amount of solid  matter is so  small compared with the
 volume of water into  which it is thrown, that it is disseminated
 through the mass, and thus  lost to observation,  and, in  many
 cases, to chemical tests.
    A river in its flow loses water by evaporation, by being  di-
 verted for manufacturing and other purposes, and in some places,
 through crevices in a rocky bed or by a slower process of per-
 colation if  the bed be  gravelly.  On the other hand, the stream
 receives water  from tributaries more or less pure  than  itself,
 and its volume is further  increased by the  entrance of ground
 water or by actual springs  rising in its bed.   On this account we
 cannot calculate the extent to which dilution will take place with
 any great accuracy, but that the apparent disappearance of much
 of  the  foreign  matter which finds its way into the stream is
 really owing to dilution is evident when we undertake to trace
 the course  of some substance  not liable to undergo any  changes
 which  will result  in its actual disappearance.   The  chlorine,
 which  exists in  the form  of chloride  of  sodium (common salt)
 and other chlorides, furnishes us with what we need.
    All natural waters contain a small proportion of chlorine, very
 small in inland waters, slightly increased in waters near the sea.
 Chlorine is a universal accompaniment of  sewage, generally in
 the form of chloride of sodium (common salt), and occurs also in
 most manufacturing refuse.  All the chlorine used in the process
 of bleaching is eventually  washed away, and that contained in
 the various compounds of this element  which are used in dye-
 houses and print-works finds its way in  the  end into the drains
of the establishments.  On this account, although  harmless  in
the combinations in which  it finally exists, its presence indicates
the presence, now or formerly, of refuse material.  Of course, in
regions containing  salt-springs and salt-deposits, these  statements
would require modification.  It  is to be remarked  further, that 
SELF-PURIFICATION OF  STREAMS.             69
while there do exist compounds  of chlorine which are insoluble
in water, and other compounds which are gaseous, and while it is
true that  chlorides are absorbed to a  limited extent  by earth
filters  and  by growing plants,  for  all practical  purposes  we
may say that the chlorides once dissolved  in  the water are not
removed either as insoluble or gaseous compounds.
    If, now, we take the case of the Blackstone River as instanced
in Table IX, page 62, we shall see that  the 3.80 parts of chlorine
in Mill Brook have become 0.92  part five miles below, after the
brook  has been merged in the  river, and twenty  miles further
still the river water contains only 0.36 part.  Believing, as we do,
that this decrease of the chlorine is due almost entirely to dilu-
tion, we must believe also  that the decrease in the amount of the
organic matter is largely due to the same  cause.   Owing to the
fact that the organic matter is much more liable to  conversion
into insoluble and volatile compounds, no  one would deny that
an appreciable amount of  organic matter is chemically changed
and actually destroyed, but emphasis should be laid  upon what
we believe to be a fact—namely, that the apparent self-purifica-
tion of running streams is largely  due to dilution, and the fact that
a river seems to have purified itself at a certain distance below a
point  where  it was  certainly polluted,  is  no  guaranty that the
water is fit for domestic use.
    Referring again to  Table IX, it would appear that  no effect
is produced upon the waters of the Merrimack by the cities of
Lowell and Lawrence, which throw into the stream the greater part
of their sewage and the waste from all the mills.  Is the organic
matter of all this  refuse destroyed by oxidation  or other chem-
ical change ?  Certainly not! Let us  take  simply the  results of
examination above and below Lawrence.  Between  these two
points the river receives the refuse  from nearly all  the manufac-
turing establishments, a large proportion of the excreta of the
factory  operatives, and a  portion of the sewage of  Lawrence.
Moreover, the lower station is so  short a distance below the city,
that no chemist, probably,  would believe that  any  considerable
destruction of organic matter could take place in the rapid flow
for so short  a  distance, and if, upon chemical grounds, the evi-
dence was not sufficient, the floating soap-suds, with still unbroken
bubbles, and other materials borne down upon the  current show
the same thing.  Now, in spite of this  addition, which must be 
70
WATER  SUPPLY.
 considerable, there is only a slight increase in the total dissolved
 solids, and in the albuminoid matters, while the chlorine is prac-
 tically the same or slightly decreased.  We know, positively, that
 chlorine  compounds,  in  large  quantity,  are  thrown  into  the
 river at Lawrence, and yet, just  below the  city, the proportion is
 not  increased.   Although absolutely large,  the  amount is  too
 small compared with the  great  volume  of water to produce an
 appreciable increase.   From these considerations with reference
 to the  chlorine, it is  evident that, in the case of  the soluble
 organic matter  it is not necessary  to suppose any destruction or
 decomposition  ; the apparent decrease or lack of increase may be
 explained, as in the case of chlorine, by the fact of dilution, and
 where the distance between the two points of  examination is so
 short as in the instance now under  discussion (above and below
 Lawrence), this is no doubt the main cause concerned.
   It may be well, in this connection, to say  that it is often diffi-
 cult  to prove satisfactorily the actual pollution of a stream until
 by the accidental or unusual discharge of some peculiarly offen-
 sive  or characteristic  substance the matter is  placed  beyond
 doubt.  Carbolic acid has sometimes served  this purpose ; thus,
 a few years ago, the taste and odor of carbolic acid were so strong
 in the  water  supplied to Newark, Jersey City and Hoboken,
 that  the water  could not be used for domestic purposes. These
 cities take their water from the  Passaic River  at a point where
 the  stream is always polluted, but at this  time particular atten-
 tion  was  called to  the polluted condition of the water supply
 by the washing of a quantity of carbolized  paper at a  mill  on
 one  of  the  tributaries of the stream.*  The following  circum-
 stance is  related with reference to  the water supply of Cincin-
 nati, Ohio, f
   " The  eddy  of the  Deer Creek Canal caused much pollution,
which  was  brought to  the attention of the consumers in  a
marked manner in  1867 by the  burning of a large  distillery  on
the  canal.  The whiskey found its  way into the canal, thence
into  the river, and thence to the consumers."
   Much  depends,  of  course, upon the size of the  stream into
which the refuse is thrown.  Thus, while into the Merrimack  at
* Leeds : Journ. Amer. Chem. Soc., iii.
f  Engineering News, 1881, p. 162. 
PREVENTION OF POLLUTION.
71
Lowell, even during the summer, it would be necessary to throw
more than  one hundred tons of  solid matter daily in order  to
increase the amount in the water by one grain  to the gallon,*
another and smaller stream  might be hopelessly fouled by a
single factory.
    Ullik has made some interesting calculations with reference to
the Elbe, in Bohemia, and shows that the entire  product  of the
well-known sulphuric acid works  at  Aussig, if allowed to flow
into the river, would increase  the  amount of  sulphates by only
one twenty-fourth, and  that the mineral matter in the sewage
from all of the 5,000,000 inhabitants of Bohemia would increase
the mineral matter in the stream by only  one twentieth.!
    A question which we should be glad to have answered is this:
To what extent must a polluted liquid be diluted in order to be
safely used  for domestic purposes ?  The answer, however, none
can give.  We do know this: it has been shown by actual exper-
iment that the spores of some  of the  lower orders of  vegetable
organisms are very difficult to deprive of vitality; they may be
frozen or heated to the boiling temperature, or they may be kept
in a dry condition for years, and then, if placed in a favorable
medium, become active and produce their kind.   Admitting the
presence of disease germs  in a liquid, the liquid  may be diluted
until the chance of taking even a single germ  into the system is
so small that it may be disregarded ; and yet,  if the prevailing
theory be true, a single germ, if taken, might produce disastrous
results.   It  is easy to push the demands for purity to an absurd
extent ; all  reasonable  precautions  should  be taken to  insure
purity, but there is a point beyond which  it is  foolish to attempt '
to go.   In the present  state of our knowledge we should, how-
ever, err on the side of safety, and the mere fact  that  chemical
analysis fails to detect  impurity  should  not  be  accepted as a
guaranty that a water is fit to drink.

                    Prevention of Pollution.

   The pollution of streams  can be prevented  only  by legal
enactments.  Cities and  towns claim the right  to discharge their
* Fifth Annual Report of the Mass. State Board of Health.
f Abh. d. math, wissenschf. Classe d. k. bohm. Ges., x. 
72
WATER SUPPLY.
sewage  into a water-course on which they may be situated, and
unless a nuisance is thereby created within their own boundaries,
they are not  likely, of their own motion, to do anything toward
a different disposal of the sewage, as all  other methods involve
additional expense.  Riparian owners, especially when they have
located  manufactories for  the  sake of  the conveniences which
the stream affords, will not, as a rule, adopt any method for dis-
posing of  their sewage or manufacturing refuse which involves
expense, unless compelled to do so.  Even where waste material
may be  utilized,  so  that the expense is met by a corresponding
return, the vis inerti<2 is so great that legal  pressure is generally
necessary to secure the adoption of plans which, in the end, may
prove as advantageous to the manufacturer as to his previously
injured neighbor.
   The  following is  a very brief  summary  of  the legal restric-
tions which exist in several European States: *
   "In  Prussia, though there  are no special regulations for the
inspection of factories in order to prevent the pollution of  run-
ning waters, there are very simple means of  interference in every
separate case  of  pollution by manufacturing refuse.  Thus, by
the statute of July I,  1861, most  of  the  processes which are
likely to pollute water require a special police license ;  and by a
statute passed as far back  as 1843, no water applied to dyeing,
tanning, fulling, or other similar  purposes, is to  be suffered  to
enter a river, if thereby the means  of procuring clean water be
endangered to the neighborhood ;  and by a regulation dating
from October 28, 1846, the owners of such works as impregnate
the water used in any manufactory, with  materials hurtful  to
meadow land, must,  in accordance with the judgment and direc-
tion of the police authorities, precipitate their materials in  sub-
sidence ponds, or otherwise, under penalty of fine.
   " In  Belgium  there are various  local  regulations, having the
force of law, which  impose a penalty upon those who pollute
rivers, either  by throwing in solid materials, which may impede
the course of the stream, or by allowing liquid matter, which may
foul or corrupt the water, to flow into  it.  Manufactories which
produce such refuse are bound to construct reservoirs sufficiently
large to contain a day's supply of this refuse, in order  that suf-
* Rivers Pollution Commission.  First Report 1870, p. 42, 
PREVENTION OF POLLUTION.
73
 ficient settlement may take place, and the supernatant liquid only
 is allowed to be run off."
    In France, several royal ordinances and decrees of  the Coun-
 cil (1669, 1672, 1773, 1777, 1783), forbid the pollution of streams.
 All of these ordinances and decrees, which still have the force of
 law, prohibit, under penalty, casting into the Seine or  into other
 water-courses, " aucunes ordures, immondices, gravois, pailles ct
 fumiers."  The laws of December 22,  1789, and August 16-24,
 l79°> grant to departmental and municipal authorities power to
 preserve the purity of streams, and to  interpose if the waters
 become a source of ill-health.  A ministerial decision, dated July
 24, 1875, reaffirms, in principle, the decrees of 1773 and 1777.*
    That the laws, even of well-policed  countries like Germany
 and France, do  not  succeed in wholly accomplishing the object
 desired, is evident from the present condition of certain streams,
 notably of the Seine and Spree.  In England, there were formerly
 laws similar to those existing in France ; but the enormous de-
 velopment  of the manufacturing industry in that country, and
 the national sensitiveness as to the liberty of the subject,  served,
 in course of time, to render them all dead letters.
    The  Public Health Act, of 1848,! gave local authorities power
 to build sewers  and  discharge them into streams wherever  they
 saw fit.   Then began, on a large scale, the pollution of the rivers
 of the country which has  since become so great an evil.   By the
 Nuisances Removal  Act,  1855, provision was first made  for en-
 joining individuals, towns and corporations against the pollution
 of streams.   To provide for the full carrying out of the require-
 ments of the act, Section IX  contains  a clause that  the local
 authorities  shall appoint  or employ a sanitary inspector or in-
 spectors.  In 1858,  local  authorities were  rendered  liable  to
 injunction for polluting streams.
    In  the Sewage Utilization Act of 1865, we find this clause;
 " Nothing contained in this act or any  other acts referred  to
 therein (z. e., all the sanitary acts previously passed), shall author-
 ize any sewer authority to make a sewer so as to drain direct into
 any stream  or water-course."  By the same  acts the powers of
 sewer authorities were extended as to the pollution of streams.
   * Schlcesing et Durand-Claye.  Rapport.
   f This sketch of English  legislation is condensed from the Seventh Annual
Report of the Mass. State Board of Health. 
74
WATER  SUPPLY.
 Seventeen years had sufficed to reverse entirely the laws on the
 subject.  In 1848, towns were urged to empty sewage freely into
 the most convenient water-courses.
    The first Rivers Pollution Commission was appointed in 1865 ;
 the second was appointed in 1868, and their last report (the sixth),
 was printed in 1874.   Largely as a result of the careful  and com-
 prehensive investigations of these commissions, and especially of
 the second one, there was passed, in 1876,  a Rivers  Pollution
 Prevention Act,* which was certainly a great step in advance,
 although the act is not satisfactory to sanitarians in all respects.
 The provisions of the act are, briefly,  as follows : f
    I. Prohibition as to casting solid matter (ashes, dead animals,
 etc.) into water-courses.
    II. Prohibition   as to casting  sewage proper  into  water-
 courses.  In case, however, of sewage discharged by channels in
 use or process of construction at  the date of passage of the act,
 it will be sufficient  to show that the  best  practicable and  avail-
 able means are used to render harmless the sewage so discharged,
 and the Local Government Board may allow to sanitary author-
 ities time, in order to adopt such means.
   III. (1)  Prohibition  as to  casting  poisonous,  noxious,  or
 polluting refuse from manufactories into water-courses, with the
 same provision as above with  regard to channels already in use
 or in process of construction.  Proceedings against manufactories
 can be  taken only  by consent of the Local Government Board,
 who must be satisfied that means for rendering the manufactur-
 ing refuse harmless  are  reasonably  practicable and  available,
 under  all the circumstances of the  case, and that no material
 injury will be inflicted upon the interests of the manufacturers.
   (2) Restrictions as to solid matter  from mines.
   The following definition was formulated  by the Rivers Pol
 lution  Commission (1868) of liquids  which  should be deemed
polluting and inadmissible  into any stream, but they  have not
been established by legal enactment.
   {a) Any liquid which has not  been subjected to perfect rest
in subsidence ponds of sufficient size for a period of at least six
hours, or which having been so subjected to subsidence, contains
   * The text of this act may be found in the Eighth Annual Report of the Mass.
State Board of Health, p. 73.
   f Quoted from Ninth Annual Report of the Mass. State Board of Health. 
PREVENTION OF  POLLUTION.
75
in  suspension more than  one  part  by weight of dry  organic
matter in  100,000  parts by weight of the liquid, or  which, not
having been so subjected to subsidence, contains  in  suspension
more than three parts by weight of dry mineral matter, or one
part by weight of dry organic matter in 100,000 parts by weight
of the liquid.
    {b) Any liquid  containing, in solution, more than two  parts
by weight of organic carbon or 0.3 part by weight of  organic
nitrogen in 100,000 parts by weight.
    {c) Any liquid which shall exhibit by daylight a distinct color
when a stratum of  it one inch deep is placed in a white porcelain
or earthenware vessel.
    {d) Any liquid which contains in solution,  in 100,000 parts
by weight, more than two parts by weight of any metal except
calcium, magnesium, potassium, and sodium.
    {e) Any liquid  which in  100,000 parts by  weight contains,
whether in solution  or suspension, in chemical combination or
otherwise, more than 0.05 part by weight of metallic arsenic.
    (/) Any liquid which, after acidification with sulphuric acid,
contains,  in  100,000 parts  by weight, more than one  part  by
weight of free chlorine.
    {g) Any  liquid which contains, in 100,000 parts by  weight,
more than one part by weight of sulphur, in the condition either
of sulphuretted hydrogen or of  a soluble sulphuret.
    {h) Any liquid possessing an acidity greater than  that which
is produced by adding two parts by weight of real muriatic acid
to 1,000 parts by weight of distilled water.
    (?)  Any liquid possessing an alkalinity greater than that which
is produced by adding one part by weight of dry caustic  soda to
1,000 parts by weight of distilled water.
    {k) Any liquid exhibiting a film of petroleum or hydrocarbon
oil  upon  its surface, or containing  in  suspension,  in  100,000
parts, more than 0.05 part of such oil.
   To these  standards was attached  the  proviso,  that  " no
effluent water  shall be  deemed  polluting  if  it  be not  more
contaminated with  any of the above-named polluting ingredients
than the stream or river into which it is discharged."
   In this country  comparatively little has been done in the way
of legislation from  a  sanitary point of view,  as the polluted
streams are still few in number,  and the necessity for legislation 
76
WATER  SUPPLY.
has not become pressing.  In some States there are general laws
against the obstruction and pollution of water-courses, or special
provision for securing, to a certain extent, the purity of streams
or other waters actually used as sources of  supply.
   In  the  District of Columbia there is  a law of the United
States (1859), which provides penalty for committing any act by
reason of which the supply of water to the cities of Washington
and Georgetown becomes impure, filthy,  or  unfit for use.  In
Iowa, by an  act  of 1864, it  is punishable by fine or imprison-
ment   to  throw  any dead animal into any river, well, spring,
cistern, reservoir, stream, or pond.  In  Michigan, an act of  1865
prohibits the putting of  offal, etc.,  into waters  where fish are
taken.  In Nebraska,  by act of  1873, there  are penalties for
putting carcasses or  other filthy substances into well, spring,
brook, or any running water of which use is made for domestic
purposes ; the corrupting of  any water-course is  declared to be
a nuisance.
   In  Tennessee, by act of  1866-7, rendering water unwhole.
some  is declared a nuisance.  In Vermont, by act of 1852,  a
penalty was  enacted against any one  putting any dead animal
or animal substance  into rivers,  ponds, springs,  etc.  In Wis-
consin there are laws providing against the erection of slaughter-
houses on  the  banks of any river, stream or creek, or throwing
any carcass or offal therefrom in or upon  the bank of  any such
river,  etc.  In Texas,  by act of i860, polluting or obstructing
any water-course, lake, pond, marsh, or common sewer, or con-
tinuing such  obstruction or  pollution,  so as to render the same
unwholesome or offensive to  the  county, city, town, or neighbor-
hood  thereabouts, or doing any other act or thing that would be
deemed and held a nuisance at  common law, is made a  misde-
meanor.*
   The Texas  law, just alluded to, indicates very well what  is
generally the character and effect of  legislation on this subject.
If any persqn or corporation pollutes  a stream in such a way
that the result would be held a  nuisance  at common law, or if
the pollution is  so great that  it  can  be absolutely proved that
water, which is  taken for domestic use, has become " impure,
  * These facts are gathered from " A Digest of American Sanitary Law, by Henry
G. Pickering, Esq.," in Dr. Bowditch's Public Hygiene in America. Boston, 1877. 
PREVENTION OF POLLUTION.
77
filthy, or  unfit for use,"  it is, under such circumstances,  possi-
ble in some cases to obtain an injunction against the offending
parties.  But  to absolutely prove that  a water is impure, filthy
or unfit to  use, is difficult unless  one  can present in court  the
body of  some person who  has  died by the  use of  the water;
and, according to certain decisions which have been  made, it
would seem that nothing short  of this will suffice.  In several
States a local  or  a State  Board  of Health has some powers in
these matters, but they are mostly nominal and  rendered  of no
avail  by rights of appeal.  A great deal of attention has been
given to the pollution of  streams in the State of Massachusetts,
and the two following sections from chap. 183 of the Acts of 1878
would seem sufficiently explicit :
   "Section  1.   No person or  persons, or corporation, public
or private,  shall  discharge directly, or cause to be discharged
directly, human excrement into any pond in this Commonwealth
used as a  source of water supply by any city or town therein, or
upon whose banks  any  filter-basin so  used is situated, or into
any river  or stream so used, or upon  whose banks  such  filter-
basin is situated, within twenty miles above the point where such
supply is  taken, or into  feeders  of  such ponds, river or stream
within such twenty miles.
   " Section 2.  No person or persons,  or corporation, public or
private, shall  discharge,  or  cause  to be  discharged, into any
pond in this Commonwealth used as a source of water supply by
any city or  town therein,  or  upon whose banks any filter-basin
so used is situated, or into any river or stream so used, or upon
whose banks  such filter-basin is situated, within twenty  miles
above the point where such supply is taken, or  into any feeders
of such pond, river, or stream within such twenty miles, any sew-
age,  drainage, refuse, or  polluting matter of such quality and
amount, as either by itself, or in connection with other such matter,
shall corrupt or impair the quality of the water for domestic use,
or render  it  deleterious to health." *
   It would seem that these provisions  would give all necessary
security, but two practical difficulties occur.   Section 3 reads as
follows:
   "The  prohibitions contained in the  two previous sections
shall not be construed  to destroy or impair  rights already ac-
* The italics are the author's. 
78
WATER  SUPPLY.
quired by legislative grants, or to destroy or impair prescriptive
rights  of drainage or discharge, to the extent to which they
lawfully exist at the date of the passage of this act : And nothing
in this act contained shall be  construed to  authorize  the pol-
lution  of any waters in this Commonwealth in any manner now
contrary to law.
   "This act shall not be applicable  to the Merrimack or Con-
necticut  rivers, nor to so much of  the Concord River as lies
within the limits of the city of Lowell."
   The deciding whether a prescriptive right exists is not always
easy, but the chief difficulty lies in the fact that while the State
Board  of Health is given  the power to issue orders  " to  cease
and desist," the parties  have a right  of appeal to jury.   This
jeopardizes  the whole matter at once, and,  as the  pollution
often  takes  place  in one county to  the detriment or supposed
detriment of water-users in another county, the jury are  apt to
be influenced by local interests.
   While it  must be confessed that  the present state of legisla-
tion is unsatisfactory, it  must be admitted that it is practically
impossible absolutely to prevent the  pollution of streams,  and it
will probably  always be  necessary that certain streams should
serve  as  carriers of refuse.  At  the  same time, the amount of
pollution  should  be  kept within bounds,  so that the  water,
although it may not be fit or  safe for domestic use, shall not be
an actual nuisance; while some streams are thus devoted to viler
uses, those which are reserved for  purposes of water supply
should be guarded with all  possible care.   It is evident that
nothing is more unphilosophical than that  one town should be
allowed to discharge its sewage into  a  water-course which is the
most available source of water supply for a town lower down on
the stream.   Each  river  basin  should be under the control of
some central authority by which  conflicting interests should be
harmonized.  An accurate  survey should be made of the whole
area, and no town should be  allowed to introduce a water sup-
ply without  due consideration being  given to the future of the
supply, and  to the question of disposing of  the sewage of the
town supplied.  Moreover, while sanitary considerations  are of
the highest  importance,  manufacturing interests must also be
considered,  and no  undue burden  laid upon legitimate  indus.
tries. 
CHAPTER  V.
SURFACE WATERS AS SOURCES OF SUPPLY.  {Continued)
                 Animal and Vegetable Life.
    No  surface water  is free  from  various forms of animal and
vegetable life; it is seldom, however, that any trouble arises from
this cause when the water is taken directly from running streams.
On the  other hand, the water  in lakes and ponds and in storage
reservoirs is extremely liable  to be disagreeably affected by the
growth  and decay of animal  and more  especially  of  vegetable
organisms.
    Animals.—The presence of fish in a source of supply is an
advantage rather than otherwise.  As far as known, any trouble
arising from their presence is quite  temporary and  accidental.
The sudden discharge into a stream of material injurious in itself,
or which, by using up  the oxygen of the water, makes  it impos-
sible for the fish to breathe, may cause their destruction in large
numbers.  Occasional  epidemics, in  some cases due to fungous
growths, may affect  large numbers of fish at the same time.  In
such cases, the sources of supply must be watched  and the dead
fishes removed as  thoroughly  and as rapidly as possible.
    Among  the smaller forms of animal
life we  have the so-called water-fleas, of
which the Daphnia pulex (Fig.  6)  and
the Cyclops quadricornis (Fig. 7) are fa-
miliar  examples.   These or
other similar animalcules
swarm in many surface waters
at certain seasons of the year,
and occur more  or less abun-
dantly in all pond and river
waters.   They no  doubt, to a
certain extent, tend to purify
the water by removing objec-
tionable substances, and are in turn devoured by other animals.
Fig. 6.—Daph-
  nia pulex.
Fig. 7.—Cyclops quadri-
      cornis. 
8o
WATER  SUPPLY.
They are easily removed by the simplest sort  of  filtration, but
there is no probability that they are unwholesome if taken with
the water.  These minute  crustaceans secrete an oily substance
under their shells (carapaces) which some have held to be the
cause of certain bad  tastes which have affected water supplies,
but it is extremely doubtful if this is  a correct explanation of
the trouble.  It may be said, however,  that a fishy  odor has been
frequently noticed on the  Lake of  Geneva, very perceptible to
the passengers on the passing steamboats, occasionally over the
entire lake.  This  odor is ascribed  by Dr. F. A. Forel *  to  an
unusual mortality—from some  unknown cause—among the en-
tomostraca which swarm in the lake, and which usually by day
descend to a depth of 5, 10, or 20 meters, rising to  the surface at
night.   It is possible that some of the temporary  bad tastes in
surface waters may be due to a similar cause.
   In 1881, a portion of the water supply of Boston, Mass., was
in a  very  bad condition.   The water  contained an  unusual
amount of  organic  matter and possessed a very disagreeable
odor  and  taste.  This bad condition of the water  was found by
Professor Remsen,f to be mainly due  to the presence in one of
the reservoirs of  a large quantity of a Spongilla, or fresh-water
sponge, in a more or less decayed condition.  Several species of
the fresh-water sponge  occur in ponds and streams, and they
are found even in the masonry conduits to a limited distance
from the source  of supply.   The following cut will give a fair
idea of the general appearance of  the Spongilla  fiuviatilis,  al-
though  the details are  somewhat unsatisfactory.   The  sponge
belongs to  the animal kingdom, and the animal substance is dis-
tributed over a  network of spicules.  No. 2  in  the figure  at-
tempts to  show some of the "winter buds," or bodies by which
the animal is propagated, held  in a mass of spicules;  No. 3 is a
portion of the same enlarged.   The sponge is harsh to the touch,
and with  a good lens something of its  structure may be made
out; for confirmation, however, it is well to burn  off  a little on
a fragment of mica, moisten  with  water (or  better,  with acid,
muriatic acid or dilute aquafortis) and  examine with a good lens
  * Private communication.
  f Report of the Joint Standing Committee on the Impurity of the Water Supply.
Boston City Document, No. 143, 18S1. 
ANIMAL AND  VEGETABLE  LIFE.
8l
or a low-power microscope (say from 50 to 100 diameters) for the
spicules.  The larger spicules, which are observed by examining
with a low power the sponge of  the Boston water supply, appear
as in Fig. 9 (drawn with
a power of about 150 di-
ameters).  Other spic-
ules  are covered with
short spines, and the so-
called  winter-buds, by
which  the  sponge  is
propagated, are furnish-
ed with minute spicules
which  are,  in certain
species, very  character-
istic : thus in 5. fluviat-
ilis they are  birotulate,
as shown in  Fig. 10, a.
Some  of  the  smaller
spicules of the sponge
which occurs in the Bos-
ton  water  are  shown in
Fig.  10, b and  c.  Fig.
10  was drawn with  a
power  of  about 260 di-
ameters.
    Although the spon-
ges have caused trouble
in Boston  and  perhaps
elsewhere, the fact that
they exist  in  a water
supply need not neces-
sarily  awaken  appre-
hension.   They  prob-
ably  exist   in  nearly
all surface waters,  and  the spicules  are among  the common
objects found  by a microscopic  examination  of  the sediment
in  natural waters.*   According  to  Dr. R. D. Thompson, the
Fig. 8.—Spongilla Jluviatilis.
   *See for example, the plates in  Hassall's Microscopical Examination of the
Water supplied to the Inhabitants of London and the Suburban Districts.  London,
1851.  Also, Neuville, Des Eaux de Paris.  Paris, 1880.
           6 
82
WATER  SUPPLY.
dried Spongilla fluviatilis contains 26 per cent of organic matter.
This organic matter is highly nitrogenous, although no particular
                                    analyses   seem  to  have
                                    been made of the fresh wa-
                                    ter sponges.   The  tissue-
                                    substance of  salt  water
                                    sponges—fibroin (Mulder)
                                    or  spongin  (Stadeler)—
                                    has the following compo
                                    sition :
	Posselt.	Crookewit.
Carbon....	48-75	47.16
Hydrogen .	6-35	6.31
Nitrogen ..	16.40	16.15
Oxygen ...	28.50	26.90
Iodine		I.08
Sulphur ...	....	O.50
Phosphorus		I.90
Fig 9.—Sponge spicules.
100.00
100.00
   Among the other forms of animal life which may be here
mentioned, is the Hydra, which is common enough in ponds,
adhering to aquatic plants.   The body is narrow and elongated;
it  is generally attached
by  the  base  to  some
plant or other solid ob-
ject while the other ex-
tremity of the body is
furnished with long slen-
der  arms  or  tentacles,
which   move  about  in
search of the animalcules
on  which it   feeds.   It
may be worth while to
mention the fact that in
a conduit where  a gate-
house  admits  access to
the interior, the  author
has seen the rapidly flow-          FlG- ^.—Sponge spicules.
ing water  swarming with  these  creatures,  so  that, in dipping
up a single glass  of water, a dozen  or  twenty  of  the hydras
would  be taken at the same  time.   On the bottom  and sides
 
ANIMAL AND VEGETABLE  LIFE.
83
Fig. 11.—Hydra viridis.
of the conduit were, no doubt, hundreds of  thousands of the
                                little animals, but no recogniz-
                                able effect was produced on the
                                water by their presence or by
                                their  death and  decay, which
                                must have followed.
                                   Of  course there are many
                                other animal inhabitants of fresh
                                waters, and when we descend to
                                microscopic organisms we have
                                a very great variety of forms.
                                The term Infusoria is often used
                                to cover all these minute animal
organisms, which are grouped  under  orders  and families and
genera and species like the higher
animals.   Scarcely  any  natural
water is free from these infusoria,
and some of them are peculiar to
impure waters, but, as they can
be  recognized and studied only
under the microscope  by those  familiar with
such matters, we need  not  dwell upon them
here.
   Plants.—Generally speaking,  the flowering
aquatic plants, such  as are known as eel-grass,
pond-weed, pickerel-weed, etc.,  are  in them-
selves of no disadvantage, while growing, to the
pond or reservoir in which they grow ; they are,
indeed,  of positive advantage, in oxygenating,
and  so,  to a certain extent, purifying the water.
If such  plants, or portions of them, decay in a
limited volume of water they produce a very of-
fensive smell and taste.  This is, in general, true
of plants  aquatic and non-aquatic.  It  is well
known that the water in which  flax is " retted "
becomes  very offensive.*  In   some  experi-
ments made  by  the  author a few years ago,
the worst  smell  obtained was  from the seed-
Fig. 12.—Pond-weed
   (Potamogeton).
   * In this connection see Reichardt, E., " Schadliche Wirkung des Rostwassers
von Flachs und Hanf fur die Fischzucht."  Arch. d. Pharm., ccxix, Heft 1, 1SS1. 
84
WATER  SUPPLY.
bearing portions of a species of Potamogeton (a common water
plant), and  Professor Brewer, who has made  much  more exten-
sive experiments, obtained a very fishy odor  from the decay in
water of the  leaf-stalks  of a  pickerel-weed,  Pontederia  cordata,
which grows on the margins of the pond from  which  New Haven
receives its supply (Whitney Lake).
    While the odors and tastes obtained from different plants
differ from  each  other, in a stream or pond  where the volume
of water is  comparatively large  and the opportunity for aeration
is great, the various tastes seem  to blend into a more or  less
marked marshy or pondy flavor.  Sometimes, even  in large bodies
of water, a  distinctive taste is noticed; thus, in the fall of the
year, the water of pur ponds and lakes which  are surrounded by
woods acquires more  of  a  bitter or astringent  taste, which
is to be  referred  to  the dead  leaves  at  that season most
abundant.
   A word or two may be  in  place with reference to the action
of fresh water upon vegetable  matter in  its bearing upon im-
pounding  reservoirs.  When vegetable matter  decays  in  moist
soil, it  is converted into a brown or black substance generally
known as humus; this is really a mixture of a number of differ-
ent bodies, and from it  chemists have  isolated a variety of sub-
stances, such as humic acid and humin, ulmic acid and  ulmin.*
The acids of the humus, by oxidation,  undergo chemical change,
to be sure,  being converted  into  crenic and  apocrenic  acids,
which, or rather the salts of which, are found  in surface waters ;
but when the vegetable  matter is  thoroughly " humified," as in
the case of peat, it exerts apparently no bad effect on the water,
except by giving it a brown color and  a somewhat earthy taste.
   When a recently felled tree is exposed  to the action of the
water, or when bushes or even grass and weeds  are killed by being
flooded with water, the sap and more soluble matters are leached
out and putrefy, or, in the  presence of much  air,  undergo other
forms of decomposition.  This  action will  take place, no  mat-
ter  under what depth  of  water the vegetable matter  may be
placed, but  the effect will be less marked  as the amount  and
motion of the  water is greater.
   * For a resume of the investigations on the composition of humus, see Julien:
Proc. Amer. Assoc, xxviii (1879), p. 313 and foil. 
ANIMAL AND VEGETABLE LIFE.
85
    After the more soluble portions are extracted, the subsequent
 decay proceeds with  extreme slowness, provided the remaining
 cellulose or woody fiber  is  kept continually covered with water,
 but alternate exposure to  air and water soon causes decay, as
 every one knows.   In a natural or artificial reservoir the inevita-
 ble variations of level are very disadvantageous.   As the level is
 lowered, those aquatic plants which grow in shallow water die,
 and if the  water rises after only a short  interval it  becomes
 impregnated with the products of their decay; if a considerable
 interval elapses, land  plants grow upon the exposed surface, and,
 being drowned by the rising waters, tend to  its contamination in
 the same manner.
    It appears from this, that in the construction  of impounding
 reservoirs,  the mass  of  growing  plants,  as well as the  soil in
 which they  have their roots, and which of itself contains more or
 less soluble  organic matter,  should  be removed as thoroughly as
 possible, especially if the  water is to be of no great depth above
 it when the reservoir is flooded.  If the reservoir is filled with-
 out such removal of the organic accumulations, a long time may
 may be required before  the chemical changes have completed
 themselves  and the water  become well  suited for  use, but the
 complete removal of  the  soil, that is, as far as such removal is
 practicable,  is not a guaranty  that no trouble  will arise from a
 newly filled  reservoir.  Occasionally the vegetable  decay in a
 new reservoir gives rise to much offence from the formation of
 sulphuretted hydrogen.   A marked instance  of this  occurred
 in  one of the  basins of the Sudbury  River supply, Boston,
 Mass., the summer after  it  was first filled.  The whole mass of
 water in the basin was permeated  with the odor, which was so
 strong on the  leeward cide of the pond as to incommode the
 passers-by.  The odor was not that of  pure  sulphuretted hydro-
 gen as prepared in the laboratory, and the gas was no doubt ac-
 companied by other chemical  products.  The water drawn from
 the depths  of  the  pond  had the odor of an antiquated privy.
 The presence of sulphuretted hydrogen was made very  manifest
 by suspending  in the  gate-house  cloths wet with a solution of
 acetate of lead ; these became yellowish-red, and finally jet black,
 owing to the formation of sulphide of lead.
   The formation of the sulphuretted  hydrogen is readily ex-
plained.  The flooding of the  basin started the decay of a large 
86                     WATER SUPPLY.
quantity of organic matter; this taking place in the presence of
the sulphates contained in  the water changed them  into sulph-
ides, and from these sulphides thus formed sulphuretted hydrogen
is liberated by the  acid products of decay.   This same  change
takes place to a less degree in  almost all ponds and reservoirs.
The gas is formed, however, mainly  at the bottom, and as it dif-
fuses upwards and mixes with the overlying water it  comes into
contact with  the oxygen in the water and is  decomposed.  The
sulphur is set free and sinks to the  bottom,  or in a very finely
divided state flows off with the water.  In salt or brackish water
which  receives  sewage, these  changes take  place  on  a much
greater scale.  A while ago the author had occasion to  examine
a number of samples of mud from the lower part of the Charles
River,  a tidal stream which receives a portion of  the sewage of
Boston, Mass.   In  all cases sulphur in considerable  quantity
could be extracted from the mud by the use of proper solvents.*
   The plants which give  the most  trouble  in connection with
water supplies belong to the  class of cryptogamous (non-flower-
ing) plants which the botanists call alga—plants which grow in the
water,  or in moist places, and usually contain chlorophyll (green
                                      coloring matter) or some
                                      allied  substance.   Not
                                      all  algae  are, however,
                                      harmful.  The  so-called
                                      confervoid growths are
                                      made up of plants of fila-
                                      mentous structure, grass-
                                      green, or  in  some cases
                                      bluish-green  in   color,
                                      forming tangled  masses
                                      readily removed  from
                                      the water, and, when so
                                      removed, shrinking enor-
                                      mously in apparent bulk,
                                      and  drying  away  to  a
                                      grayish or colorless mass,
                                      in some cases looking al-
                                      most  like coarse paper.
Fig. 13.—a, Diatom (Slauroneis) ; b, Desmid
  {Euastrum) ; c, Desmid (Micrastetias).
Eighth Annual Report Boston City Board of Health.  (1879-80), pp. 12-18. 
ANIMAL AND VEGETABLE LIFE.
87
 Plants of  this character grow in  almost all reservoirs or other
 bodies of  water  exposed to  the  light and air, both in still and
 running water; they either float about in masses, or are attached
 more or less firmly to rocks and stones  and other solid objects.
 By their  growth they do no harm to the water in  which they
 flourish ;  and as  they  are readily arrested by  ordinary  wire
 screens, or easily removed by  rakes or scoop-nets, their presence
 causes no serious inconvenience in water used for town supply.
    Then there are the diatoms and desmids (Fig. 13), which are
 interesting objects under the  microscope, and  occur in consider-
 able abundance and  great variety ; they are not, however, as far
 as we know, of any significance  in surface waters, at least, from a
 sanitary point of view.
    The vegetable organisms which cause the most trouble and
 inconvenience are those which appear  as greenish  specks, or mi-
 nute  straight or curved threads, diffused  through the water—
 visible enough if a large quantity of water be looked at, but per-
 haps  almost escaping notice in  the small quantity which would
 be  taken  up in  a single glass.  It  is  true  that the  individual
 plants are  in some  cases distinguishable by the naked eye ; but
 their form and structure can be  made  out only by  use of the
 microscope.  If collected together as a scum, which  often  hap-
 pens, especially on the windward  shore  of  a pond, the  scum is
 not coherent, is easily broken  up,  either  by  a wrind setting in the
 opposite direction, by a shower  of rain, or by artificial agitation.
 The appearance has been sometimes described as that  of meal or
 of fine dust scattered through the water. The number  of  indi-
 viduals is  almost  infinite; and under favorable  conditions they
 increase with great  rapidity.  Their presence  gives a decidedly
 green or  greenish yellow tinge to large bodies of water; and
 their death and decay often cause considerable offence  to the
 sense of smell of  those sojourning in the neighborhood, and to
 the sense  of taste of  those  obliged to drink the water.  The
 troublesome species belong, almost all, to the family  of Nostocs,
 and of these the  number which  have been known to produce
 difficulty is small; this may, of  course, be due  in  part to imper-
 fect observation.  A single species each of Ccelosphcerium and
 Clathrocystis, two or more of  Anabama  and one of Sphczrozyga
have  been observed in considerable quantities in the neighbor-
hood  of Boston, Mass. 
°o                    WATER SUPPLY.

   Fig. 14, c gives a general idea of the appearance  of the Cla-
throcystis ceruginosa when magnified some 300 diameters.   This
plant is often found in much larger masses than indicated in the
                         Fig. 14.

cut; in fact,  the  little  sack-like  masses are sometimes large
enough to be made out by the unaided eye, although no idea of
the structure can be thus obtained.   Fig. 14, a attempts to give
an idea of the Anabcena circinalis, one of the Nostochinece; this
plant occurs very  frequently in  ponds and  in sluggish streams.
Another common  variety of the same genus is similar, except
that the filaments  are straight instead of curved; and there are
other genera of alga which  occur in the same way as the Ana.
bana, and present a similar appearance.
   These algse, when present in  any considerable quantity, give
a repulsive appearance to the water, and when they are in a'state
of decay they communicate  to  it an offensive taste and odor.
Fortunately, in most  cases, the  trouble which they  cause is of
short duration, although often recurring in the same water sup- 
ANIMAL AND VEGETABLE LIFE.
89
ply year after year.   Their presence is  not a sign of contamina-
tion, as they occur in natural ponds removed from all polluting
influences.  While, however, they do grow in pure waters and in
old and clean ponds, they seem to grow  more abundantly in water
containing mud  and vegetable extractive matter, as in newly
filled  reservoirs;  so  that, while  immunity from their  presence
cannot  be guaranteed in the case of any pond, they may with
some certainty be looked for in  dirty and especially in shallow
ponds.   A warm  temperature and shallow water are perhaps
of even  more importance than the products of decay of higher
plants, for all surface waters contain the ammoniacal and mineral
salts necessary for the growth of  the algae.
   Whether the presence of these minute algae gives an unwhole-
some character to a water which  is otherwise suited for domestic
use, is an open question  ; but such information as the author has
been able to get from various sources  coincides with the state-
ment of the Mass. State Board of Health, who investigated the
matter when a certain portion of the water supply of Boston was
affected  in  this way.  They say * that the evidence " tends to
show that the plant acts  mechanically chiefly, perhaps like unripe
fruit, when  affecting the health at  all, in causing diarrhoea;  but
that the filtered water is harmless."  It is known that fish often
die in ponds containing an abundance of the scum-forming algae,
probably on account of the cutting off of the supply of air ; there
is also one case on record where cattle have been killed by drink-
ing pond water which contained  large quantities of a species of
Nodularia, a plant which has  something of a resemblance to the
Anabana.\   This was in Australia.  No such cases have come to
the knowledge of the writer here.  When the algae are alive and
fresh, horses and  cattle  drink the water readily, in preference to
spring water:  when decay  takes  place, the water  sometimes
becomes so  offensive that they refuse to drink it.  In this condi-
tion it is manifestly unsuited for  domestic use.
   As far as our present  knowledge extends, there  is nothing
that  can be  done  to exterminate the algae from ponds  in which
they occur.   Sometimes in reservoirs, when the algae have  col-
lected as a scum,  it is possible to  float them off from the surface

   * First Annual Report of the State Board of Health, Lunacy and Charity, 1879.
Supplement, p.  xi.
   f Nature, xviii (1878), p. 11. 
90
WATER SUPPLY.
by means of properly arranged waste pipes, and in reservoirs the
conditions favorable for their collection and decay may be re-
moved by grubbing up  the lilies and other pond-weeds around the
borders.   Special devices sometimes avail in special cases.   The
experience at Poughkeepsie, N. Y., is instructive.  Here the
Hudson River water was pumped on to filter-beds, thence, after
filtration, into a small uncovered reservoir.   In summer, after the
temperature  of the water reached 700 F., an alga, one of the
oscillariacea,  developed in the shallow water on the beds and in
the reservoir, and by its death and decay in the pipes caused much
trouble.  The trouble occurred every summer, until the following
method of procedure was adopted by Mr. The. W. Davis, the
then superintendent.   As soon as  the  temperature of  the river
water approached 700, careful watch was kept on the temperature
and on the quality of the water delivered.   As soon as  the taste
or odor was  noticed in the  city, the reservoir was shut off and
the water pumped  directly  from the river into  the mains.  In
this way all trouble was avoided and there were no complaints.
   With reference to the minute organisms, animal and vegetable,
it is a curious fact that  certain forms will sometimes  suddenly
appear in places where for years previous  they have never been
known to occur,  and they  may disappear as suddenly as  they
came.  In other cases,  forms which have been known to be pres-
ent to  a limited  extent will  increase  enormously, owing to  con-
ditions of which we are quite ignorant.

             Odors and Tastes of Surface Waters.

   Surface waters often possess peculiar odors and tastes.  These
are  sometimes explicable, as in the case of the odor of sulphu-
retted hydrogen  referred to  on page 85.  Then there are other
odors (with accompanying tastes), which are quite certainly due
to the  algae.  These odors are quite various.  Mr. Fteley (Sud-
bury River) speaks of a musty odor ; at Albany it was spoken of
as a musty and cucumber odor; at Springfield (Ludlow Reservoir),
the first summer after the reservoir was filled there was a most
distinct odor of  green  corn,  perceptible for  a quarter of a mile
from the pond on the leeward side.  The pond was covered  with
a slime  of algae, partially decayed;  and the same  marked  odor
was noticed at the water troughs along the line of the aqueduct. 
TEMPERATURE OF SURFACE WATERS.
91
   When, under the excessive heat of summer, the algae are col-
lected in masses and begin to decay, a most  abominable pig-pen
or horse-pond odor is sometimes noticed in the ponds ; but this is
seldom  noticed in the water drawn  from  the service pipes, al-
though  a foul odor similar to that common in "dead-ends" does
occur when water containing the algae stagnates in the pipes.
   Besides the tastes and odors which may with reasonable cer-
tainty be ascribed to the growth or decay of organized beings,
there have been  certain  conditions of the water in the case of
many water supplies which are  very enigmatical, and for which
no satisfactory  explanation has  been offered.  The  so-called
" cucumber " taste, and the other tastes characterized as " fishy "
or " oily," occur when the water is of its ordinary purity and in
waters  naturally  pure.   Some have maintained that the tastes
ought to be due to the presence or to some peculiar condition of
the algae, but as it is impossible to discover any unusual amount
or condition of those algae, which are, so far  as we know, harm-
less, and which are always  present,  and as none of those algae
which are known to produce bad tastes and odors are found, it is
rather difficult to accept  this explanation.   Since Professor Rem-
sen has found reason to believe  that the recent condition of the
water in Farm Pond is due in part, at any rate, to  the decay of
a sponge, it has been suggested that we have here  the cause of
the various  difficulties heretofore unexplained.  While it seems
to be undoubtedly true  that the sponge may, under  certain cir-
cumstances, produce what is properly spoken of as a " cucumber "
taste, there are many cases on record where it is difficult to believe
that this can be the cause; and with reference to such cases, for
the present, we can only say, " We do not know."

               Temperature of  Surface Waters.

   One of the great disadvantages to which surface water is
subject  is the variation in temperature.  The water in winter is
but a few degrees above the freezing  point,  and in summer the
temperature is so high that the water is not agreeable as a bever-
age unless artificially cooled.  The use of ice is so general in the
United  States that much less stress is laid  upon this point than
in other countries, but, of course, a considerable proportion of the
inhabitants in the thickly settled  parts of our cities are unable to 
92
WATER SUPPLY.
supply themselves regularly with ice.  Of late years iced water
has been supplied at several public fountains  in New York, and
perhaps in other cities.  It would be difficult to isolate the effect
of the temperature of the water on the public health from  the
general effect of the hot weather, of  eating unripe and decayed
fruit, and of other causes, all of which  affect particularly  the
poorer class of the population.  In England, the increased death-
rate of the warmer months has been connected directly with  the
temperature of the water supply.  Thus, in the report  of  the
Registrar General for July 22, 1878, we find:
   " The high mortality of the  week is due to diarrhoea, which
becomes  fatal in London when the temperature of the Thames
rises above  6o° F.   Thus  the Thames temperature, which had
been 6o°, rose in the last week of June to 650; in the following
weeks it was 68°, 66°, 67° F.  The weekly deaths from diarrhoea
and simple cholera, which  had been 23, rose to 78, 156, 256, 349
in corresponding weeks."  To show  that this increase was not
due  simply  to  the increased atmospheric temperature  and its
attendant discomforts, it  is stated that " the  deaths from diar-
rhoea are differently distributed  in the fields of  the water com-
panies ; thus the deaths in the  last four  weeks were 786 in the
districts supplied by the Thames and Lea waters, whereas the
deaths in the districts supplied with water drawn from the chalk
by the Kent company were 19;  out of the same population, the
deaths in the former were  to the deaths in the latter as 3 to 1."
The temperature  of the Kent company's water at the wells was
uniformly 520 F.;  at  the  same  time it must be noted that the
waters differed not simply with respect  to temperature. The
water of the Kent company is harder, and, what is perhaps more
important, it contains but  little organic matter.
   Baldwin Latham, while believing that "the summer diarrhoea
is governed by  the influence of  the  temperature of our water
supply, as invariably the  disease becomes epidemic when the
water, whatever be  its source of supply,  reaches a temperature
of 620 F.  (i6°.7C.)," attempts to show that  the  temperature of
the water delivered to the consumers is much  less  dependent
upon the original temperature at  the source than is usually sup-
posed, and that if  the water is carried  for any considerable dis-
tance in the  mains, it approaches or acquires the  temperature of
the ground  in  which the pipes are  laid, as  appears from the 
TEMPERATURE OF SURFACE WATERS.
93
following table.*   Here the  Kent  water, alluded to as having a
uniform temperature at its  source, appears, when  delivered, as
variable as the  water of  the Thames.  He  asserts f  that  the
general mortality  in  London  from diarrhoea is practically the
same in the districts supplied from the rivers as in those supplied
by the  Kent Water Company, but that the water  in  the latter
region does not reach its highest temperature until later in  the
season, owing-to the advantage which the  lower initial tempera-

         TABLE X.—Temperature of London Water Supplies.
[The degrees are Centigrade.]
	Kent Company's Water.		Thames	The Ground at a depth	
Date.			Water in	OF METERS	
	In the wells.	In the mains.	the Mains.		
				O.838.	1.448.
July, 1878......	IO.59	16.80	18.39	17.66	15-47
	IO.67	16.62	17.70	I7.I6	16.05
	10.71	14.78	14.92	15.28	15.04
October, ......	IO.68	12.90	12.87	12.53	13-05
	IO.61	8.17	7-47	6.98	904
	IO.50	5-98	5-M	3-72	6.12
	IO.45	5.06	4-77	2.80	4.68
	10.40	5-45	5-72	3-58	4.66
	10.35	6.30	7.20	4-97	5-54
	IO.44	8.38	8.20	6.80	6.85
	IO.42	9-3&	10.20	7-32	8.31
	IO.57	12.63	14.25	13-01	11.23
ture gives to it.  It will be understood that Latham's figures have
reference to the temperature acquired in the service pipes;\ the
water passing through the  main  conduit or even through the
large iron mains suffers  much less change of temperature than
Table X would indicate.§ Latham  has patented an  apparatus
for " tempering " the water, which consists " of  a vertical tube
driven or screwed into the ground to  a depth of about 25 feet, the
water being admitted at  the  top and withdrawn at the bottom,
and special arrangements being adopted for the protection of the
ascending pipe."   With such an apparatus  interposed in the
service connection of the house, " the range of  temperature  in

    * Quoted from Journal fUr Gasbeleuchtung und Wasserversorgung, xxii (1879),
p. 75°-
    t Journal of Society of Arts, Sept.  17, 1880.
    X The temperatures given in the reports of Dr.  Frankland to the Registrar Gen-
eral were taken in the company's mains at Deptford,  near the source of the water.
    § This matter is discussed at  length and mathematically by Perissini: Journ. fur
Gasb. und Wasserv., xxiii (1880), pp. 608 and 644. 
94
WATER SUPPLY.
the water required for dietetic  purposes need  not exceed 30 F.
throughout the year, when drawn from a 3-inch  tube at a rate
not exceeding one gallon every half-hour."
   The question of temperature is an important one in bodies of
stored water, as the troublesome algae already alluded to seem to
require  a somewhat elevated temperature (approaching  700 F.)
for their rapid and abundant development; when collected  as a
scum they are killed and enter into decay when the water be-
comes strongly heated in midsummer.  While it is,  of  course,
impracticable to  cover ponds and impounding  reservoirs, it  is of
advantage to cover the smaller storage reservoirs which  are fre-
quently used in connection with water-works to contain a  reserve
supply, or a supply for a limited number of days, and thus to pre-
vent, to a certain extent, the elevation of  temperature to which
   TABLE XI.—Observations of Temperature in Fresh Pond, Mass.*
Date.
May      4, 1878,
        M,
June      4,
        12,
        19,
        25..
July      2,
         9.
        16,
        23,
August    6,
        13,
   "     20,
        27,
November 7.
December 7,
January   2, 1879
        M,
        22,
April     14,
May     13,
Temperature (expressed in		Centigrade
	degrees) at	
a 0 u If y £ « oh H	V u a b si 0 . 3 •	15 U) 4! 1) u u -- a > 0 3 Z-HB S| 8
0	0	„
16.5	I2J-5 '	8-5
14-5	14-5 r-	8-5
19.	16.5	8.8
17-3	16.8	8.6
20.5	16.8	8.7
22.2	16.6	9.2
28.0	16.7	9-3
26.0	16.4	9.2
25-3	16.8	9.6
24.0	16.8	9.9
24.0	17-3	10.1
24.0	20.1	10.0
24.0	20.0	10.2
22.3	20.0	10.0
9-5	9.2	8-7
4-5	4-3	4-5
o-5	1.0	1.0
0.7	i-3	i-7
0.9	2.0	1.8
6.0	5-o	4-4
18.5	13-0	8-3
   * First Annual Report of Mass. State Board of Health, Lunacy and Charity, 1880.
Supplement, p. 98. 
TEMPERATURE  OF SURFACE WATERS.
95
 a small and comparatively shallow body of water is subject under
 a summer's sun.
    Table XI shows  the variation in temperature  of the surface
 water in a pond near Boston, Mass. (lat. about 420), which is used
 as a  source of city  supply;  and  also  the variation at different
 depths.
    For  making observations on  the temperatures of bodies of
 water, especially below the surface, thermometer makers supply
 instruments surrounded  by  a  copper tube  in which some of
 the water is  brought to the surface.  Where samples for  an-
 alysis are taken at the  same time,  a  chemical  thermometer
 may  be inserted in the  bottle used  for the collection  of  the
 water.   The bottle having been sunk to  the required depth,  the
 stopper is withdrawn, and after the bottle has filled it is allowed
 to remain until it is certain that the whole apparatus has acquired
 the actual temperature of the water.   It is then drawn up and
 the reading of the thermometer is taken quickly while still sur-
 rounded by water.   This method answers very well, with care, up
 to depths of 80 feet.
    A very convenient  instrument for taking  temperature at  va-
 rious  depths is the  " New Standard Deep Sea Thermometer,"
 made by Negretti and Zambra, London.  The construction of
 the thermometer is  shown in Fig. 15,  c.   To protect  it against
 pressure, this  thermometer is inclosed  in a glass  tube,  hermet-
 ically  sealed,  the  portion which  surrounds  the thermometer
 bulb being filled with mercury.  The object of the mercury is to
 furnish a good conductor of heat between the outer wall and the
 thermometer bulb, and it is  confined in  place by a partition  ce-
 mented  on to the  neck  of  the bulb.  The whole apparatus is
 inserted  into a hollow  wooden  frame containing a quantity  of
 lead shot.  When the  thermometer is  lowered to any depth, it
 descends as shown in Fig. 15, a, and the bulb of the thermome-
 ter is downward; it  is  allowed  to remain at the required depth
 for a few minutes in  order that the thermometer may acquire the
temperature of  the  place, the  mercury rising or  falling  in the
capillary tube  as in an ordinary  thermometer.   Finally, a sudden
pull is made on the line, and the instrument, owing to the resist-
ance of the water and the  consequent displacement of the center
of gravity (the shot falling to the  other end of the frame), will
turn over and be drawn upward  with the thermometer in the 
96
WATER  SUPPLY.
position shown in Fig. 15, b.  When the thermometer is inverted,
the mercury column breaks at the constriction A, and falls to the
other end of the tube, from which the  degrees are read off, as
shown in  the figure, with  the bulb of the thermometer upper-
most.
   As with  any thermometer, it is necessary to determine the
DESCENDING.
ASCENDING.
Fig. 15, c.
Fig. 15, b.
error  of  graduation once for  all, and the  error of the zero
point  from  time to time.   For very  nice work, a  correction
should also be made for the temperature of the mercury column
at the time  of reading, but  in  ordinary work this is  not  neces-
sary.

               Examination of Surface Waters.

   In choosing a surface water as a source of supply, there are 
EXAMINATION OF SURFACE WATERS.          97
 certain concessions which must be made.  In the first place, the
 water will be, almost inevitably, somewhat colored, especially  if
 taken from a pond or lake ;  in the second place, there will usually
 be a slight " pondy " taste, even in  the best of surface waters.
 Considered simply as drinking water, surface water will always
 be at a disadvantage by the side of a pure, soft spring water, but,
 as stated on previous pages, a surface water may often be, on the
 whole, the best suited for a general supply.
    In examining as to the suitability of  any source of surface
 water, after determining whether a sufficient amount can be ob-
 tained directly or by means of storage reservoirs, the desirability
 of the source can be ascertained better by a survey of the drain-
 age area, and  by a knowledge of the  present  population and
 sources of pollution, and the probable increase in the future, than
 from the results of chemical examination of the water, the inter-
 pretation  of which  is sometimes attended with difficulty.   It
 may be possible, it is true, to  state from the chemical examina-
 tion of a single sample that no considerable or no  appreciable
 contamination exists ; it is impossible to recommend a water for
 drinking  without knowing  something of the situation  and sur-
 roundings of the source from which it is taken.
    The principal difficulties in the way of the satisfactory chemi-
 cal examination of surface waters are three in  number: In the
 first place, the volume of water is generally so large that, even
 when polluting matter is known to be present, the  dilution is so
 great as to prevent the detection of unmistakable evidence of
 contamination.   In  the second place, all surface waters contain
 more or less of organic substances—substances containing carbon
 and nitrogen—which it is impossible  to refer definitely to animal
 or vegetable sources, or otherwise to  distinguish as harmless and
 harmful.   In  the third place,  the water  of  such  streams and
 ponds is subject to  very considerable variation, so  that  the ex-
 amination of a single  sample is  of  comparatively little value.
 With reference to the second point something has already been
 said in the chapter  on water analysis.  It may be said further
 that the substances which form the  most  offensive part of the
 soluble vegetable matter are albuminous  in  character,  and the
chemical effect on the  water is to increase the amount  of what
is  designated as  " albuminoid  ammonia ; " that is, they  contain
nitrogen,  which, under  the  analytical treatment, is evolved and
           7 
98
WATER  SUPPLY.
 measured as ammonia.  It is  unfortunately  impossible by ana-
 lytical means to distinguish whether this "albuminoid ammonia"
 is to be ascribed, in  any given case, to vegetable or to animal
 origin.   No doubt the  excrement of fishes, their dead bodies so
 far as they are not consumed by their living comrades and by
 the  animalcules, and the  bodies of the animalcules  themselves
 add to the nitrogenous organic matter  in our surface waters.  As
 a rule, in waters not contaminated by sewage, the animal matter
 forms only a trifling proportion of the  entire  organic matter, but
 the recent  investigation of Professor Remsen  shows that in some
 instances the  animal  matter (as from sponges) may be apprecia-
 ble and of practical importance.
    In the case of a bad condition of the water  arising from the
 decay of an unusual  amount of animal or vegetable matter on
 the bottom or sides of  a reservoir, or from the presence of algae,
 the water is ordinarily  characterized by an abnormal amount  of
 soluble organic matter, which shows itself in the common method
 of  analysis  as " albuminoid ammonia,"  or  in  the  Frankland
 method  as  " organic carbon "  and " organic  nitrogen."   But,  in
 order to judge whether the amount  is abnormal  or not, it is nec-
 essary to have an extended series of analyses, and this is seldom
 at hand.  The effect of algae may be well seen by a study of the
 weekly analyses of the Springfield water for the years 1876 and
 1877, and of the  Mystic during 1879, as shown in the respective
 water reports.*
   As, in this country,  waters have been and are  most frequently
 examined  by  the " ammonia"  process,  attempts  have  been
 made to fix the limit of " albuminoid  ammonia " which may be
 allowed  in  a  surface water.   Wanklyn,  as  stated  on page 41,
 looks upon 0.010 part of "albuminoid ammonia" in 100,000 as
 suspicious, and upon 0.015 part as sufficient to condemn a water,
 and some analysts are inclined to adopt this standard for our sur-
 face waters; such  an absolute  standard is, however, impractica-
 ble, and would exclude  many waters which are known to be free
 from  contamination and to be perfectly well suited for domestic
 use.   With  reference to this matter  Dr. Smart says: +

   * See Annual Reports of  the W7ater Commissioners of the City of Springfield
<Mass.), 1877 and 1878.  Also, First Annual Report of Massachusetts State Board of
Health, Lunacy and Charty.  Supp., pages 119, 120.
   f Buck's Hygiene, ii, p. 128. 
EXAMINATION OF SURFACE WATERS.
99
    " The waters of the purest mountain streams in our unsettled
 West, where animal  contamination is an  impossibility, contain
 0.014 part per  100,000 of albuminoid ammonia.  At other times
 they may yield 0.020, 0.025 or more, and yet be regarded as com-
 paratively innocent."
    Dr. Smart found the Black's Fork, Wyoming, to contain 0.014
 part in  100,000  when most  free from surface admixture,  and
 0.028 part when swollen by  melting snows.   The Little Wind
 River, Wyoming, a stream running over a rocky bed and contain-
 ing only  about 3.75 parts of  total solids in 100,000, gave 0.034
 part of " albuminoid ammonia."  The North Platte River yields
 from 0.030 to 0.050 part in 100,000 at different times.  The ques-
 tion may be  pertinently asked how  it is that our surface waters
 contain so much more organic matter than the waters  of Great
 Britain ?  Dr. Smart says :  " These streams ought to be pure, if
 pure water is to be found in nature, as they run through no pop-
 ulous districts and are thus free from the sources of contamina-
 tion against  which sanitary officers are most  on guard.  They
 spring from a cleft  in the rocks, are  mostly rapid in their course
 until they reach the plains, and are fed by the rainfalls and melt-
 ing snows.  There  seems nothing left  by way of explanation
 but  the  wildness of the country through  which they  run.   In
 England the  fields are fenced  in  and the soil  cultivated to the
 very banks of  the  stream, the woods  are well kept,  and  the
 swamps are drained and reclaimed ;  but here there is no cultiva-
 tion ; vegetation lives, and, instead  of  being  garnered  up, dies
 and decays.  The forest trees fall and rot where  they fall.  I
 have been up in the Uintah Mountains, where are the sources of
 the  Black's Fork, and among the pines covering the slopes of
 the ridge there are more fallen trees in all stages of decay than
 living  ones in  those untouched forests.   Through  such dead
 vegetation the  streams have to force their way, and it would be
 singular indeed if they did not take up  a portion of the soluble
 organic matter.   But, in  addition, in the tangled willow growths
 of the valleys, where, as in the forests, the growth of to-day rises
 from the decay of ages, the beaver dams up the stream,  and
vast masses of  water are stagnated,  to dissolve the dead vegeta-
ble tissues and  find  their way by slow degrees back into  the beds
of the running  water."
   " That the dissolved organic matter is vegetable in its origin, 
IOO
WATER  SUPPLY.
 is also shown  by the absence of chlorides and nitrites, and that
 it is recent, by the frequent absence of ammonia."
    It must not be understood  that the presence of an excess of
 vegetable matter is absolutely a matter of indifference.  Waters
 thus charged  may be the cause of diseases  of  the digestive or-
 gans, without  doubt.  Whether they may also cause any of the
 so-called zymotic diseases or give rise to specific diseases of pe-
 culiar type, is  doubtful.
    Dr. Smart, whose opinion is entitled to much weight, ascribes
 the  " mountain fever " of the West to this  cause (compare page
 52).  He says:
    " As animal matter, in certain stages of its decomposition, or
 enveloping specific germs, gives expression to its presence in the
 system by  the development of typhoid  fever, so vegetable mat-
 ter, in certain  stages of its decomposition, or enveloping specific
 germs, gives rise to an adynamic remittent,  for which  the writer
 has suggested  the name  of aquamalarial fever.  Viewed in its
 connection with this affection, the organic ammonia should not
 exceed 0.016 part in 100,000, for when 0.020 is reached, the disease
 makes its appearance, and becomes more pernicious in  individual
 cases as the amount  increases.   Not  that aquamalarial develop-
 ments are to be expected in every case where the organic ammo-
 nia exceeds this limit, but that  experience shows a greater  prob-
 ability of their occurrence with a water thus  impregnated—ma-
 laria being  more likely to  be present with  a large  than a  small
 vegetable contamination."
   With reference to the  third point alluded to  above as afford-
 ing difficulty in the interpretation of  the results of  chemical ex-
 amination,  it may be said that the results of a single examination
 are to be received with a good deal of caution, and such results
 must be interpreted somewhat according to  the season of the
year in which the sample is taken.  The very considerable  varia-
tion to which streams are subject, as far as the suspended matter
 is  concerned, has been shown in Table VII, on page 57.   The
state of things is similar with reference to the matter in solution,
especially with streams in which the volume of water is subject
to much variation.   Thus the  Hooghly, at Calcutta,  is stated
to carry :
              21.68 parts in 100,000of "total solids" in May,
               XI-3o  "  •..........< October. 
EXAMINATION  OF SURFACE WATERS.
IOI
   The rainy season greatly increases its purity, and the melting
of the snow on the Himalayan Range helps in the same direction,
so that the water is most pure in October.*   Further illustration
of the variation to which surface waters are subject, particularly
with regard to the organic matter, may be seen from the  follow-
ing tables.  Table XII  shows  the  variation  in the sum of the
" organic carbon " and " organic nitrogen," and also in the " albu-
minoid ammonia," as observed in the case  of the  Mystic water,
which is supplied to a portion of Boston, Mass.
TABLE XII.—Examination of Mystic Water.
       [Results expressed in Parts in 100,000.]
Date.	No. of Samples.	Sum of the Organic Elements.	" Albuminoid Ammonia."
June, 1879...............	Average of 2 samples « 4 .< " " 4 » " " 3 " " 5 " " 2 " " 1 " " " 2 " " " 3 " w 4 « " 4 " " 12 "	O.478 0-775 O.605 O.448 o-333 0-393 0.297 0.364 0.486 0.852 0.526 0-375	
Tulv ...............			
August ...............			O.035 0.026 0.020 0.014
			
			
			
			O.OII 0.012
			
			
			0.034 0.022 0.014
    In this case, the  large variation was  partly due  to  the pres-
ence  of  an abundant growth of algae,  the trouble  being at its
height in the latter part of July and during August.   But, in the
absence  of any such growth, the variation is often very  great.
Weekly  examinations  of the Cochituate  supply of the city of
Boston from July, 1876, to  July, 1877, showed a variation
    in the ammonia................... from 0.0005 to 0.0056 part in 100,000
    in the  " albuminoid ammonia "..... from 0.0099 to 0.0176  "  "   "
    in the  total solids.  ............... from 3.72   to 5.58    "  "   "

    Further illustration of this point is afforded by Tables XIII
and XIV.
    Table XIII  contains the results of monthly examinations of
the water of Glasgow, Scotland, as reported by Professor Gustav
Bischof of  the Andersonian University.   The water comes from
*Proc. Inst. Civ. Eng. Gr. Br., lxiv, p. 361. 
102
WATER SUPPLY.
TABLE XIII.-Examination of Glasgow Water by Professor Bischof.

                  [Results expressed in Parts in 100,000.]
Date.
May  12, 1873
June  16,
July  18,
Aug.   1,
Sept.   1,
Oct.  14,
Nov.  24,
Jan.  15, 1874
Feb.   5,
March 10,
April  1,
May   5,

   Average ..
Organic
Carbon.
O.204
O.181
O.192
0.209
O.156
O.256
0.177
0.154
O.25I
O.185
0.169
0.235
0.197
 Organic
Nitrogen.
O.OI7
0.016
0.008
O.OII
0.047
0.028
0.035
0.021
0.008
0.007
0.003
O.OII
0.018
Sum of Or-
ganic Ele-
  ments.
0.221

O.I97
0.200
0.220
0.203
O.284
0.212

0.175
O.259
o. 192
0.172
O.246
0.215
an  unpolluted  Highland lake, Loch  Katrine, and flows  some
thirty-six miles in a  masonry conduit.  Table XIV, which, like
No. XIII, is compiled from the Sixth Report of  the Rivers Pol-
lution Commission, shows the variation in the water of the sev-
eral companies which supply London  with filtered river water.
These are not monthly averages, but the results of the examina-
tion of single samples taken at monthly intervals.

  TABLE XIV.—Variation in Monthly Samples of London Water,  1873.
Name of Company.
Chelsea........
West Middlesex
Southwark.....
Grand Junction.
Lambeth......
New River.....
East London...
Organic Carbon.			Organic Nitroc	
Maximum	Minimum	Mean	Maximum | Minimum	
at any one	at any one	of 12	at any one	at any one
time.	time. O.I2I	Samples. O.I97	time.	time.
O.447			0.067	0.013
0.341	O.II4	O.173	O.055	O.OI5
O.396	O.II8	O.186	O.060	0.020
O.412	O.II7	O.183	O.050	0.016
O.449	O.I30	O.206	O.065	0.021
O.257	O.059	0.107	O.032	O.OIO
0.333	O.IO9	O.I75	O.082	0.015
 Mean
 of 12
Samples.

 0.034
 0.028
 0.030
 0.032
 0.040
 0.018
 0.035
   It may be said, in general, that  no source of surface supply
should be adopted on the strength  of examinations made in the
winter season, and in the case  of ponds and lakes the examina-
tion should include  a  careful  survey  of the  shallow  portions
during the hot weather, with a view  of  discovering the possible
presence of noxious algae.   Negative  results in this direction will
not, however, guarantee future immunity. 
EXAMINATION  OF SURFACE  WATERS.          IO3
   As already intimated, the preliminary examination of a sur-
face water, from a sanitary point of view, concerns  itself chiefly
with the present and probable future pollution, and this must be
considered with reference to the volume of water with which the
polluting substances will be diluted, taking care to err rather on
the side of safety: the chemical examination should not, how-
ever, be omitted, as the results, if  properly interpreted, may be
of great value.  Tables XV and XVI will  furnish data for com-
parison in the case of surface waters.

           TABLE XV.—Examination of Surface Waters.
[Results expressed in Parts in ioo,oco.]
			z a		Z.Z,	£	to ■ [I] 5 P		Hardness.			
	w5 0	z 0 a X	0 0 «		w a < z	0 u z						a
												-j
Geological For-	j 0 j 0	< U	fc		< Or 5	3 s .			£	~		S <
mation.		u z < a K	y z < 0 K	< Z 0 s s		0 z U a 0 h	Sjz	H Z 5 0 ■J X	rt O o. B	V c rt E	rt O	h O 0
	H	O	O	<	z,	H	tu	U	H	fc	H	2
Igneous rocks.....• Metamorphic, Cam-	5-5	O.278	O.O33	O.OOI	0.002	0.035	0	1.13	0.1	2.0	2.1	18
												
brian, Silurian,												
and Devonian....	5-12	O.293	O.O24	0.002	0.006	0.031	3	0.92	0.3	2-5	2.8	81
Yoredale and Mill-												
stone Grit, and												
non-calc a r e 0 u s												
Coal-measures ...	8-75	o-377	O.O33	0.003	O.OIO	0.050	6	1.05	0.4	4-3	4-7	47
Calcareous portion												
of Coal-measures.	22.79	0.346	O.O33	0.007	0.016	0.056	33	1.52	4.0	8.3	12.3	26
Surface Watef.s												
from Cultivated												
Land.												
Non-calcareous dis-												
tricts. ... ......	9-52	0.276	O.O34	0.007	0.089	0.128	635	1.49	0.6	4-3	4-9	3'
Calcareou s d is-												
tricts...........	30.08	0.268	O.053	0.005	0.257	0.314	2,306	2.24	12.4	8.2	20.6	12
												
   In Table XV are presented the results obtained by the Rivers
Pollution Commission from the examination of a large number
of samples of  surface water from  various geological regions, the
organic matter being indicated by the determination of the " or-
ganic carbon"  and  " organic  nitrogen."   In Table  XVI are
brought together the results of the examination of various Amer-
ican  surface waters, mostly in actual use as sources of supply,
the organic matter being indicated  by the " albuminoid ammo-
ma.
* Sixth Report of Rivers Pollution Commission. 
TABLE XVI.—Partial Analyses of Surface Waters.

             [Results expressed in Parts per 100,000.]
O
4^
Locality.
Boston, Mass.....,


Plymouth, Mass.. ..

New  London, Conn
Springfield,  Mass...
Jersey City,  N. J ...

Newark, N. J......

Philadelphia, Pa.. ..
Wilmington, N. C..


Cincinnati,  Ohio ...
Louisville,  Ky.....
Evansville,  111......
Indianapolis, Ind. ..
Minneapolis, Minn..
Fray  Bentos, S. A..
Higueritas, S.  A....
Description.
  Main Supply,
  Lake and River
Mystic Lake
Pond.............
Reservoir.....
Passaic  River.
Schuylkill "
Cape Fear River.
Ohio
White
Mississippi
Uruguay
Date.
July, '76-July, '77.
July, '77-April, '79
Oct., '79-June, '80.
June, 1877........
March, 1880.......
December, 1879...
Jan.-Dec, 1876...
August  1876......
January, 1875.
January, 1880.
June, 1881----
August, 1881..
1880...........
1880..........
1880...........
1877...........
September, 1877.
 No. OF
Samples.
43
40
17
45
Total
Solids.
4-3
 9-
 3-
 2.
 3-
 4-
27-
11.
16.
10.
12.0
IO.3
 5-6
 5-6
14.2
11.7
18.6
28.0
18.6
 8.6
 8.7
Ammonia.
0.003
O.O04
O.Oig
O.O08
O.OOI
0.006
0.017
0.013
O.OIO
O.OIO
O.OI2
0.015
0.021
0.004
0.008
O.OII
 tr.
0.012
0.003
0.003
0.003
  o
Albuminoid
 Ammonia.
0.014
O.O15
0.015
0.017
O.OIO
0.008
0.052
0.022
0.019
0.015
0.020
0.037
0.044
0.017
0.016
0.048
0015
0.020
0.014
Chlorine.
9. if
i.oj
6.if
0.4 J
0.8
1-3
0.6
0.4
0.8
0.6
0.9
0.4
1 1
0.2
0.2
0.4*  W. R. Nichols.
2.0*
0.7
0.8
G. H. Cook.
C. R. Cresson.
C. W. Dabney.

W. R. Nichols.
C. H. Stuntz.
T. C. Van Nuys.
S.  F. Peckham.
3
>
H
M

w
a
* These amounts of chlorine are approximate—not averages.
f High Water.
X Low Water. 
CHAPTER VI.
          GROUND WATER AS A SOURCE  OF SUPPLY.

    A PORTION of the water which falls as rain or snow sinks into
the earth,  and  where  the surface deposit  is  gravel  or  other
porous material  overlying some impervious rock, the water col-
lects to constitute the  ground water of the locality, the water-
table of the  engineer.   The  rivers which flow through such  a
deposit, or  the ponds and lakes which are situated in  it, deter-
mine the level of the ground water in  their banks; but as we
recede  from the  banks the water level is  found to rise more or
less regularly, according to the character of  the porous stratum.
Although subject to fluctuation, the ground water often  main-
tains a  very uniform  relative level over large areas:  its height and
fluctuations are  important factors in the sanitary condition of
any locality.
    The cause of the rise of the ground water as we recede from
the wells—a fact which  has been established by numerous obser-
vations in this country and in Europe *—is  evident : the water
falling upon the whole water-bearing area would naturally raise
the level of the ground water; that level cannot be permanently
higher  than the  water in the  natural  drainage channels in their
immediate neighborhood, as there is a continual passage of water
through the  porous  material to  the visible streams  or  lakes.
Owing  to the resistance of the material through which the water
passes,  the  surface will  be an inclined  one, and the  amount of
inclination  will depend  upon  the  resistance encountered.  On
Long Island, N. Y., the inclination is quite uniform from  the

    * A great many profiles resulting  from actual measurements, and showing the
inclination of the ground water, may be found in the Berlin and Munich reports, the
titles of which appear on pages 217-218. In  the latter the profiles include the sur-
face levels, the level of the ground water, and the level of the underlying impervious
stratum, and are very instructive.  See also, The Brooklyn Water-Works and Sewers.
New York, 1867. 
io6
WATER  SUPPLY.
central ridge to the ocean or to Long Island Sound, and averages
about seven feet to the mile.   In the valley of the Sacramento
the general slope is about four feet in a mile.   In some localities
the inclination is much greater than this for limited distances;
thus, in the  neighborhood of the Taunton (Mass.), Water Works
there is a fall, in what seems  to be a continuous water-table, of
about  14  feet  in  1,000.   Besides  the  slope  towards  a visible
stream, there is often a fall in the  ground water in the direction
of the mouth of the  stream, and a corresponding flow.  It will
be understood, however, that the " flow " has reference generally
to a rather slow passage through the interstices of the  ground:
sometimes, however, on account of a lack of homogeneousness in
the water-bearing  stratum, veins of water occur, in which the
flow may be quite  rapid.
   The water obtained by sinking  a well into a stratum of sand
or gravel which has not been  artificially disturbed, is, as a rule,
bright and clear, and free, or  nearly free, from  organic matter.
Although originally  coming from the atmosphere,  in  its slow
passage into and through  the ground, the water has been sub-
jected to  a long process  of sedimentation  and  filtration, com-
bined with processes of oxidation.   In this sense, the water may
be said to have been purified by natural filtration: the process,
however, is not brought about by the means taken to collect and
utilize the water, but has been practically completed before the
demand is made upon it.

               Utilization of the Ground Water.
   The most simple method of making the ground water availa-
ble, and the one earliest adopted, is to  sink a well, covered or
open, into the water-bearing  stratum, and to pump therefrom.
Such a well, which draws its supply from the ground water proper,
is generally called  a shallow well, in distinction from  a deep well,
which may extend  into a rocky stratum, and obtain its supply from
a water-bearing fissure; and in distinction also from an artesian
well sunk to a considerable depth into underlying strata which
have  no connection  with  the ground water of the particular
locality.   This method of obtaining water from shallow wells has
been  practised from time immemorial for the supply of single
families and small communities, and is, nowadays, used on a large
scale for furnishing town supplies.  In many places the well, from 
          GROUND WATER AS A SOURCE  OF SUPPLY.       IO?

its dimensions and shape, may more properly be called a basin,
and, like the  ordinary circular wells, these basins may be either
open or covered.
   A second method of collecting the ground water is by means
of a covered gallery  or tunnel constructed  in  part of porous
material;  often the  top and sides  are built of tolerably impervi-
ous masonry or brickwork, while the bottom is of an open  char-
acter, so that the water which rises into the gallery shall  come
mainly from beneath.  An example of this now quite common
mode of collection is at  Lowell, Mass.*  The " filtering gallery "
is situated  on the northerly shore of the  Merrimack River and
parallel with it, about  ioo feet from the water's edge.   Its length
is 1,300 feet, width 8 feet, and height  (inside) 8  feet.  The side
walls have an average thickness of 2\ feet  and a height of 5 feet,
and are constructed of heavy rubble masonry, laid water-tight in
hydraulic mortar.  The walls support a semicircular brick  arch,
one foot thick, made water-tight.  Along the bottom, stone braces,
one foot  square and  eight  feet long, are  placed, ten feet from
   * A full description of the works is given in the Fifth Annual Report of he
Mass. State Board of Health.  Also, in the Third Annual Report of the Water Com-
missioners of the City of Lowell, 1873. 
io8
WATER SUPPLY.
center to center, between  the walls, to keep  them  in  position.
The water comes in at the bottom, which is covered with screened
gravel and small stones.
   One of the best examples of a filtering gallery in this country
is that which supplies the city of Columbus, Ohio.  This gallery
is a brick and cement  conduit, 36 by 42 inches, and  is shown in
process of construction  in Figure 17.   It is in  all 5,715 feet in
Fig. 17.—filtering gallery, columbus, ohio.
length, and is situated in the gravel deposit at  the junction of
the Scioto and Olentangy rivers.*  This method of construction
has been followed also at Taunton, Mass.
   A third method is to substitute for the collecting gallery a line
of iron pipes, i.e., practically water-mains, cast with a great number
of narrow longitudinal slits, and laid with loose joints.  These
pipes collect the water, and conduct it to receiving wells,  from
which the supply is pumped.  In filling the trench in  which the
pipes are laid, the pipes are surrounded on  all sides with coarse
material, of too large a size  to fall into or through the slits, and
the trench is then filled with screened material of decreasing size.
Works of this kind are  in use in various places in Germany, at
Dresden,  Hanover,  etc.  At Halle, glazed clay pipes are  em-

   * Tenth Annual Report of the Trustees of the Water-Works, Columbus, O., 1880. 
GROUND WATER AS A SOURCE OF SUPPLY.       IOQ
ployed, 47 cm.  in  diameter and 2.8 m. long; the  total area of
the slits in a single pipe is
equal  to  the  area of  the
cross section of  the  pipe.
(See Fig. 18.)
   Still  a  fourth method
consists  in the use of the
" driven- well," which is de-
scribed on page 112 and fol-
lowing pages,  but as  wells
of this description  are fre-
quently  sunk through  a
layer of clay into a stratum
of water below the  ground .ggjjl
water proper, they partake
also  of  the  character of
" artesian wells," which will
be considered in the  next
chapter.
                             ■ ■■•■'•■•-'_________1____
                                          (FROM FISCHER.)

         The Effect of Pumping upon the Ground Water.
   For the purposes of this discussion, we will suppose that the
water-bearing deposit into which a well is sunk is perfectly homo-
                                     ,        geneous
                                                         When
                                               no  water is  re-
                                               moved, by pump-
                                               ing orotherwise,*
                                               the water in the
                                               well stands at the
                                               same level as in
                                               the ground; when
                                               pumping begins,
                                               the water  falls at
                                               first  rapidly,  af-
                                               terward    more
slowly, until—if  the discharge of the pump be  uniform—a point
Fig. 19.
   * If, as is exceptionally the case, the water is delivered by gravity, the effect on
the ground water is essentially the same as if the water were removed by pumping. 
HO                   WATER SUPPLY.
is  reached where  the water is supplied at  exactly the same rate
as delivered by the pump.   Suppose, in Fig. 19, that the water
stood originally at a b, and that an equilibrium has been estab-
lished when the water in the well has fallen to c.   The water
flows from the gravel into  the well by virtue of the head or dif-
ference of level a  c, but its flow  is impeded by the resistance due
to interstitial friction against the particles  of sand or gravel, and
the water surface assumes somewhat  the  form  indicated by the
line c d.  The line c d approaches a b until it finally coincides with
it; that is, there is a point beyond which no measurable influence
is exerted on the natural level of the ground water, and its dis-
tance from the center of the well depends upon the circumstances
of each particular case.  In certain  experiments made by Sal-
bach in  the  alluvial deposit on  the  banks of  the  Elbe, above
Dresden, it was found that when the water in  an experimental
well was, by pumping, kept  constantly 2.5 meters below its nor-
mal level, the height of the ground water was measurably affected
in every direction for a distance  of some 60 meters (say 200 feet).
In experiments made by Piefke, at Berlin, the  influence of the
well was  felt  to a distance  of some 300 meters in wet weather,
and to over 700 meters at other  times ; but, while the effect could
be traced to that  distance, it was very small at the extremity of
this radius.   With the water in the well 2.33 meters below the
normal level  of the ground water, there was a lowering of only
0.35 meter at  a  distance of 50 meters, of 0.17 meter at a dis-
tance of  100  meters; and at a distance of  260 meters  the lower-
ing was through  only o. 10 meter.  In the Berlin  locality the
natural movement of the ground water was very slow, and 524
meters from  the  river the  water stood only 0.63  meter above
that in the stream.
   Where the  ground is  homogeneous, or nearly  so,  and the
water can come from one direction as easily as from another, we
have what may be called a circle of influence, with the center of
the well  for the center of  the  circle;  but if the deposit is not
homogeneous, as  is often the case, the water comes more easily
from one direction than  another, and the effect of  pumping is
felt to unequal distances from the well. As appears from Fig. 19,
the effect of the  flow of water into the well  is to form a sort of
crater from which the water is drained.  This is often spoken of
as a " cone,"  but it is not a cone, strictly  speaking.  The exact 
           EFFECT OF PUMPING ON  GROUND WATER.       Ill

 form of the curve c d will depend upon circumstances, but it will
 always lie above the straight line joining the points c and d.
    Returning again to our well, if pumping ceases, the water will
 gradually flow into the well  until finally it has found  its level
 and stands as in the surrounding ground.  If, on the other hand,
 starting with the  water in the well at  c, a larger quantity be
 pumped than before, the level in  the well will fall, and as c sinks
 to e, the water  in  the ground also  falls  and the surface will be
 indicated by  e f.  In order  that this new  and larger  quantity
 should be obtained, the  circle of influence must  become also en-
 larged, that is, a larger area must  contribute  to the supply.  The
 absolute quantity of water which can be  obtained  from any well
 depends upon the  amount  of rainfall which finds  its  way into
 the  ground water  of the region  from which the well draws its
 supply.  If the deposit were in a  basin, and  no water came from
 the  rain, the effect of pumping would be to gradually exhaust
 the  water:  thus, if the water in the well  were kept at a constant
 level, say at c, the  quantity of water delivered in a given time
 would grow less and less, and finally the surface of the ground
 water would be a horizontal plane passing through c;  if, on the
 contrary, a constant quantity were pumped, the water in the well
 would sink lower and lower  until the bottom was reached, and
 the  further delivery of the same quantity would be impossible.
 Practically, wells are not sunk in such  a deposit, but in one
 where the ground water is continually receiving accessions from
 the rain or  melting snow, or, in  some cases, from  a neighboring
 stream.  The amount which  can be obtained from any deposit
 depends finally on  the  amount received, and no such well, how-
 ever great its diameter or its depth, can be inexhaustible, although
 practically it may never  be called upon  to furnish more than it
 can supply.
   A good illustration of the effect of  a constant draught in
 permanently lowering the level of the ground water is  afforded
 by the  well in Prospect  Park, Brooklyn, N. Y.  The  well was
 constructed in 1869.
 The elevation of water table as first found, Nov., 1868,  was. ..15.6 ft. above tide level.
 Elevation of water table, May, 1879.......................x5-2
Elevation of water table on completion of the well, Dec, 1869.14.55
   Pumping began regularly on June 5, 1870; the effect has been
as follows: 
112
WATER SUPPLY.
Year.	Average Number of Gallons per Day.	Average Elcvatica of Water Table.
1870	300,000	14 15
1871	272,000	13.03
1872	437,000	IO.56
1873	233,000	II.29
1874	333,000	IO.70
1875	294,000	9-83
1876	235,000	9-83
1877	252,000	9.21
   It is seen here that an average  draught of only  304,000  gal-
lons per day has lowered the water table five feet in eight years,
and also that  the yield is diminishing, for while in 1873 a daily
draught of 288,000 gallons permitted  the water table to rise  five
inches, in  1876 a draught of 235,000 gallons was just equal to the
supply, and in 1877 a draught of 252,000 gallons again  lowered
the water.*
   In the previous discussion we have spoken of a single well of
                                              ordinary  diame-
                                              ter.   If  a series
                                              of wells be locat-
                                              ed   near each
                                              other, the effect
                                              will   be  essen-
                                              tially  the same,
                     Fig. 20.                   except the circle
of influence will become approximately an ellipse, as would be
the case if several  wells were connected  so as to  form  an open
basin or a covered gallery.   In locating a series of wells, reference
should be had to the character of the water-bearing deposit, in
order that they may not be placed unnecessarily near together.

                        Driven Wells.

   " Driven " wells,  " tube"  wells, or as  they are  sometimes
called  abroad, " American " or  " Abyssinian " wells,f are formed
by forcing wrought-iron (or galvanized iron) tubes, such as are
used for gas or water pipes, down  into the stratum  from which

   * Croes and Howell, Newark Aqueduct Board :  Report on Additional Supply,
1879, p. 61.
   \ Also called "Norton" wells, the  English patent having been taken out by  a
Mr. J. L. Norton.
 
DRIVEN WELLS.
H3
the water is to be taken.   The pipes are generally from iK to 2
inches in diameter, and furnished at the lower end with a wrought-
iron or steel  point ; above this point the pipes are perforated for
some distance with holes  to admit the water.   The pipes with
point attached  may  be driven with  a  mallet  or falling weight,
and when the top of one  tube has  reached  the surface of the
ground, a second length is attached to it with a common coup-
ling, and the driving continued  to the desired  depth.  In many
localities it is better to first drive down a suitable steel-pointed
rod or drill until water  is reached, and to insert the well-tube in
the hole thus made.*   In the perforated  points for such wells,
the greatest variety exists, it being stated that about  150 patents
have  been issued for points and cognate portions of the pipe.
The figure represents that known as Andrews' Patent.
Fig. 21.—driven well point.
   Although pipes  of  larger dimensions than those mentioned
are sometimes driven, it is usual when a large amount  of water
is required—as for manufacturing  purposes or  for town sup-
ply—to  drive a number of wells in  the same  limited  area, and
connect them  to a  common suction pipe leading to the pump.
The driven  well partakes  of the character  of the  shallow well
when its source of supply is the ground  water, but  it  often par-
takes of the character of  the artesian well, as  when it is driven
through  a layer of clay or other impervious material underlying
the ground water into another water-bearing stratum below.
   When a  driven well is forced into the ground water, and
water is  removed by pumping, the effect is essentially the same
as has already  been  described  (pages  109-112) with  an open
well.  The driven well is valuable as a means of obtaining water
on account of facility of construction, but  it involves no princi-
   * Both methods of constructing the driven well are covered by the Reissue Let-
ters Patent (No. 4,372) granted to Nelson W. Green, May 9, 1871, and the validity of
the patent has been affirmed by several legal decisions.  It is claimed, however, that
the patent is antedated by a U. S. Patent granted to James Suggett, March 29, 1864,
and by British Letters Patent granted to John Goode, Oct. 16, 1823.
           8 
ii4
WATER SUPPLY.
l(/r/WfA^mik
pie which is new as far as bringing the water to the surface is
concerned.
    It is asserted that a driven well differs from an ordinary well
in two essential respects.   In the first place,  the well, which is
always of very small diameter, is not dug or  bored, but sunk with-
out removal of the earth * in the manner already described, either
directly  or by first driving down an iron rod,  and after its re-
moval, inserting the well tube; in either case the result is a nar-
row well with air tight walls, fitting closely in the earth about it:
the tube is the well. It is further asserted that when a suction pump
is attached to the pipe a new element is introduced, and peculiar
effects are produced  by "exhausting the air," or "producing a
vacuum," and that thus the water is  drawn to the pump by a
force independent of gravity,  and to  which  gravity is,  in this
case, but auxiliary.
   These claims are,  however, fallacious.  The diagram, Fig. 22,
may represent the suction  pipe of a pump  inserted in a narrow
                                               open  well, the
                                               normal level  of
                                               the ground wa-
                                               ter being at  ab.
                                               Now,  although
                                               with   a   driven
                                               well much stress
                                               is laid upon the
                                               "air-tight" tube,
                                               it is   the tube
                                               alone that is air-
                                               tight, as any suc-
                                               tion  pipe must
                                               practically b e.
                                               The soil,  even if
                                               compacted
                                               about the tube,
                                               is not air-tight,
and as far as transmitting pressure  goes, the air which is  about

   * This is Col. Green's method, but well tubes are also driven into the earth at the
same time that their passage is facilitated by forcing into the  tube, which in this case
is open at the bottom,  a stream of water.  This water washes out and brings to the
surface the sand and clay from the bottom in advance of the driving.
■=±
Fig. 22. 
DRIVEN WELLS.
H5
the tube in Figure 22, and which rests on the surface of the water
at a, is in  no different condition whether the tube be  in natural
ground, or in a dug well, as indicated in the figure.  The air circu-
lates freely in the ground; it responds at once to any change in the
barometric pressure, and  at once  takes the place of any water
which may be removed from the interstices  of the soil.  Again,
below the water-level, the water,  like the  air above, circulates,
although less freely, owing to  interstitial friction, and, of course,
fills all the pores of the ground  close up to and around the pipe.
The statement  that the pipe  is the well, is misleading.  If we
start (Fig. 22) with the tube as  a suction pipe in an  open well,
and  imagine the well to  be gradually narrowed in diameter by
filling in around the circumference, the tube will continue to be
practically a suction pipe, even when the well  has been finally
filled up—the  well finally having become a hollow cylinder of
water, of the thickness of a  mere film if the soil is very compact.
It is quite inconceivable that the filling of the well with gravel or
sand, no matter how  closely compacted the sand  may be, could
produce any other effect  than that due to  the  increased resist-
ance to the passage of water in  the annular  space about the suc-
tion pipe.
   To show further the fallacy of the claims alluded to, let us
return to Fig. 22, in which the normal level of the ground water
is represented at a b.  If, now, a  given quantity of water be taken
continually from the point c, in a given interval of time, the slope
c d, which the water surface  will assume, will be precisely the
same whether the water is drawn  in buckets, or by a tube in an
open well,  or by a driven well, because the same amount of water
must reach the same point c in the same time, and starting from
the same original position.  If the claim be true  that more water
can be obtained by one method than by another, it follows that
the water must be supplied faster  in one case than in the other,
and there are two necessary consequences: first, if  the point c
remains unchanged, this increased  rapidity of flow must result in
an alteration of the slope of the water surface.  On the other
hand, if the quantities pumped in the same time are made equal,
then in the first case the point c will not fall as low  as in the
second.
   While we should reject, a priori, the  consequences to which
these  assumptions necessarily lead, recent experiments made by 
u6
WATER  SUPPLY.
Mr. J. C. Hoadley * show that the slope is the same whether the
given yield of water be from an open well or from a driven tube;
and that, with the same delivery, the level of the water in the
well or pipe is lowered to the same point.  The particular exper-
iment alluded to was performed as follows:  A 3-inch open pipe
was driven in pervious soil, into, and considerably below the sur-
face of the ground water, forming an open well—the earth being
removed from within.   Into this pipe a suction pipe of i^-inch
diameter was dropped  and wedged into  position, so as not to
                   close the opening of the 3-inch pipe. Water
                   was pumped for a  certain time, as much as
                   the well would supply.  Subsequently,  by
                   means  of a cap, the suction tube was  se-
                   cured in the 3-inch  pipe and the opening of
                   the latter pipe hermetically sealed.  The
                   suction  pipe   thus became,  practically,  a
                   driven  well.    Under  these  circumstances,
                   every other condition being unchanged, the
                   yield of water was  approximately the same
                   as in the previous case, the slight difference
                   which existed  being in favor of  the open
                   well.
                       It should be noted that in what has been
                   said above, the  yield of a driven well is com-
                   pared with that  of a dug well of no great
                   diameter.  If  the  well be increased in  di-
ameter  to  30, 50, or 100 feet, so that the distance c c' (Fig. 22),
becomes considerable, the limit of measurable effect on the ground-
water level will be removed farther from a,  and the yield of the
well will be appreciably greater—or, in other words, with the
same delivery, the point c will not fall so low.
   With regard to the  absolute amount of water which can be
utilized in a given locality, common  sense, as well as science, tells
us that  the amount of  water which a given deposit can furnish
must  be a definite quantity, although  to us  unknown; and al-
though  the driven wells may enable us to obtain this water more
conveniently than other methods, the  absolute amount obtain-
able is  no greater, and the supply cannot  be inexhaustible, as
   * Private communication: this statement is absolutely true only when the wells
are of the same diameter.
 
NATURAL FILTRATION.
117
 some  of  the  enthusiastic  advocates  of  the driven-well system
 would have us believe.  One great advantage which the  driven
 wells possess is the facility with which they may be sunk  for
 experiment or temporary use.   For  example, they were  exten-
 sively used by the British army in the Abyssinian expedition,
 1867-68 ; and hence, in England, they are frequently called Abys-
 sinian wells.
    It  should also be noted that the driven well ordinarily takes
 its water from a lower point than that to which a dug well would
 be sunk in the same locality.  For this reason, a driven well may
 continue to furnish water when a neighboring dug well has  be-
 come dry, and thus  the impression that the driven well is inex-
 haustible gains ground.
    On this account also, the driven well is  somewhat less liable
 to pollution than a dug well in the same locality, as the polluting
 material may be rather more diluted in  the mass of the ground
 water.  Moreover, as has  been said, the driven well often passes
 through an impervious stratum of clay, so that  the water  ob-
 tained is entirely distinct  from the ground water of the locality.
 In this way good  water may sometimes be obtained where  the
 surface conditions are very  unfavorable, but there is always an
 element of risk involved in sinking a well among sources of pol-
 lution.

                    " Natural Filtration!'
    The ultimate source of the ground water is the rain, and that
 the rain is  the proximate source of  the water obtained from a
 well sunk into a gravel  deposit  far removed from any stream or
 pond, scarcely any one  can doubt.  Such a well is that  in Pros-
 pect Park, Brooklyn, alluded to on page  in. This well is nearly
 two miles from tide-water,  and, although the natural level  of the
 water has been lowered by pumping, it  is still a number  of feet
 above tide level.  Generally, however, a  gathering  well, basin, or
 gallery is  located near  a lake  or river.  This location is chosen
 mainly because at such a place there  is  almost always a decided
 movement of  the ground water toward,  or in the same direction
 as, the stream ; but such a location is also chosen in order that
 the river may  make up any deficiency caused by the removal of
the ground water.
    It was formerly supposed, and is so even now, by many per- 
n8
WATER SUPPLY.
sons who have not  made  a study of the subject,  that  in  sucn
cases the water is derived directly from the river, and filtered  by
passing through the  intervening sand and gravel.  Undoubtedly,
in some cases, a considerable proportion is thus derived, but, as a
rule, the  contrary is true, and, where the location is such that
most of the water must come from the visible  body of water,
the supply generally proves inadequate.  The beds of ordinary
streams furnish a poor filtering surface, and the experience with
artificial filters shows how soon an originally clean  surface be-
comes clogged.*
   That the view just expressed is correct, appears from  a va-
riety of considerations.  From  the discussion  of  the effect of
pumping on the ground water (pages 109-112), it is evident  that,
from a well situated near a  stream, a  certain  amount of water
can be drawn without calling upon  the  stream at all for supply;
if, however, the  circle of influence includes a  portion  of the
stream, some of the water may come from this source, unless, as
is indeed generally the case, it is easier for the water to  come a
greater distance  through open water-bearing  deposits than  to
force its way through the silted-up and  more or  less  impervious
bed  of the stream.
   If we consider the character  of the water, there  are  certain
general facts that are at once  and readily noticeable : the water
thus obtained  is generally clear and colorless ; it  is of a  quite
uniform temperature, cool therefore in summer, and in winter
much warmer than  the water  of neighboring ponds and rivers,
which,  of  course, approach in  temperature  very  close  to the
freezing point; the water also differs in chemical character  from
that of neighboring  streams  or ponds, generally being somewhat
harder.
   With regard to the temperature, the difference is very marked,
even where the water is collected in an open  basin and  thus
exposed to the heating (or cooling) influences  of  the air.   For
instance,  in the  filtering gallery at Lowell,  Mass.,  during the
month of September,  1873, the highest temperature was 500  F.,
the lowest 490 F. ; during the month  of  October,  observations

   * The term natural filtration is objectionable only so far as it implies that the
water is obtained from the lake or stream by a process of filtration :  that the rain fall,
ing upon the ground may be said to be filtered naturally by passing through  the inter'
stices of the water-bearing deposits is, of course, true. 
NATURAL FILTRATION.                 II9
were  made on thirteen  different days  showed  identically the
same  temperature, namely,  500 F.  Between September 6 and
January 1, the highest  recorded observation is  520 F., on No-
vember 8, and the  lowest is 470 F., December  31.  There  is no
corresponding record of the temperature of the river, nor is such
necessary,  as every  one knows that  river water  varies with
the temperature of the surrounding air,  and in December must
have  been nearly at the freezing point.  At Waltham. Mass.,
where the  water is  taken by means  of an  open shallow basin,
more  marked differences have been observed between  the tem-
peratures at different seasons.  Thus  in winter, when the river
was frozen, the temperature  in the basin was about 440 F., and
the average  of  nineteen  observations  made at intervals from
August 23  to August 26, showed for  the river an  average tem-
perature of 740.1 F., and  for the basin water an average tempera-
ture of 62°.8 F.  Such instances might be multiplied indefinitely,
and it seems quite impossible to account for the observed differ-
ences by the continuous  passage of water through 100 feet  or so
of gravel.  In fact where no such differences are observed, it may
be a sign that the  water does come  from the stream, and the
water is  likely to be otherwise unsatisfactory ; thus the city of
Toulouse, in France, is  supplied by  a  number of filtering gal-
leries   in a  gravel deposit on the banks of  the  Garonne. The
original gallery was built in 182- at a distance of about 60 meters
(200 feet)  from  the river.  This furnished  water acceptable in
quality, but deficient in quantity; an increase of the length of
the gallery failed to furnish a corresponding increase in  quantity
of water obtained.  A second filtering gallery, or rather series of
connected wells, was constructed nearer to the river,  at a distance,
in fact, of only ten meters. In this case,  the water obtained man-
ifestly did  come, in part at any rate, from the  river: the water
was somewhat turbid, and what  is very instructive, the  passage
through a bank of  thirty feet, and admixture, of course, with
some  ground water,  failed to bring the water to anything like
the uniform temperature of  the  other  galleries.   The tempera-
ture fell  in winter to 2° C. (35°.6 F.), and in summer rose above
21° C. (700 F.).*   This  gallery was  therefore abandoned, and
others constructed at a greater distance  from the  stream.  These

           * D'Aubisson.  Annales des Ponts et  Chaussees, 1838. 
120                    WATER SUPPLY.
furnish water which is satisfactory, except when in time of flood
the river  covers  the whole  territory in which  the galleries are
built,  and  the galleries become filtering  galleries  in  the true
sense.
   As marked differences as  in  the  matter of temperature are
also  observed in the chemical character of the water.  This often
appeals to the eye by the absence of color in  the (so-called)  fil-
tered water, while the water of the river may be  strongly colored ;
or. if the gallery  be alongside of a pond, the latter may be filled
with  algae in a state of decomposition, without producing the
slightest effect on the gallery water.   It is, however, the hardness
of the  water which  generally attracts  attention, being noticed
where the water  is used for washing or in  steam boilers.  Usu-
ally the  ground  water is harder than the  surface water  of the
same region, but occasionally the reverse is true.  Belgrand gives
a number of examples from French  localities,  from which may
be cited the following: *

     Water of Rhone, at Lyons.................................. l6°
     Water of filtering gallery at Lyons........................... 17-94
     Water of Loire, at Nevers...................................  4.96
     Water of collecting well.................................... 20.70
     Water of Loire, at Blois....................................  7.76
     Water of the gallery (which is beneath the  bed of the river)..... 14-45

Sharpies has  found f  that  the water in the filter  gallery  near
Little Pond, Cambridge, contains nearly twice  as much lime as
that  of the pond,  and instances might be multiplied indefinitely.
In the case of the Dresden water supply the river water is harder
than that obtained from the collecting wells. %
   Even when the gallery or well is  sunk directly in the bed of
the river, or in an island surrounded  on all sides by the river or
pond, the ground  water still  contributes largely or wholly to the
supply.   Many experiments  have shown  that the  water  in a
gravel deposit directly  beneath a river differs essentially from
that  of the stream itself.
   The belief that a well or gallery located near  a pond or stream

   * La Seine, etc., pp. 463 and following.
   \ Twelfth Annual Report of the Cambridge Water Board, for  the year  1876.
Boston, 1877 ; page 30.
   X Salbach.   Das Wasserwerk der Stadt Dresden ; 3r Theil, page 7. 
NATURAL FILTRATION.
121
does not  necessarily derive its supply from the visible body of
fresh water, finds confirmation in the well-known fact that springs
are often observed to issue from the  sand along the sea shore,
even below low-water mark,* and fresh water is often obtained
by sinking wells very near the shore.  Generally, in such cases,
the surface of the ground  and the water table rise as they recede
from the shore, the ground water, derived from the rain, passing
with more or less  resistance to  the sea.   In  such wells, the
water rises and falls with the tide, as the water must  enter the
sea under the pressure of  a varying height of salt water, but the
salt water itself does  not  penetrate the  soil  and reach the well
itself.   From such  wells a certain  amount  of  water  can be
pumped.   If the amount pumped exceeds that which the ground
water  can furnish, salt water may  then be drawn into the con-
tributing area, and the water become brackish.  Even where the
ground near the sea is level, the mere effect  of the rain falling
upon the sandy area  is sufficient  to create a deposit  of  fresh
water which may crowd out or prevent the entrance of salt water.
Darwin, in the voyage of the " Beagle," discovered this  to be
the case in low coral islands of the Pacific, close to the sea; and
in Holland, Amsterdam,  the Hague  and Leyden  obtain  their
water  from collecting canals  in the  sand-dunes which  form an
almost  barren strip of  country from 2 to  5 kilometers wide, hav-
ing only  a few elevations of surface.   Sometimes  fresh water
overlies the salt, so  that shallow wells furnish fresh water,  while
deeper  wells give brackish or salt  water.  McAlpine has  made
the interesting observation that where, as on Long Island, N. Y.,
the water table slopes  down to the sea,  the  underlying deposit
of salt water slopes away from the sea—the higher and conse-
quently heavier column of fresh water at some  distance inland
being able to  displace the  salt water to  a greater depth :  thus,
the vertical section of  the body of fresh  water, in the direction
of its flow, would be that  of an elongated wedge.  Salt water
has been  found underlying the  fresh water in other localities—
   * A remarkable example of this occurs at the four iron forts at Spithead, Eng.
Here wells are sunk on artificial islands, at a considerable distance from the shore,
and, although two of them are over 550 feet deep, they pass entirely through sand and
gravel.  In spite of this location, the water of the wells contains only a small propor-
tion of chlorine (18.6, 11.4, 4.1, 7.6  parts in 100,000 respectively^, showing that
almost no sea water finds its way into the wells.— The Analyst, April, 1883. 
122                   WATER SUPPLY.
for instance, at Hull, in England *—where the salt water is sup-
posed to be due  to the infiltration of sea water, and  not to the
mineral character of the rock.

 Preliminary Examination of a Proposed Ground Water Supply.
   The least satisfactory  point  in connection with ground-water
supplies is that the amount of water to be obtained in any one
locality is limited in amount, and it is very difficult  to tell  in
advance  how large  an  amount a  given region  can  be  relied
upon to supply, except as a result of thorough surveys and long-
continued experiments.
   The effect of pumping upon the level of the ground water
and information as to the direction of its flow may be obtained
by driving a number of iron  pipes with perforated " points "  at
regular distances, preferably in two  lines at right  angles to each
other, intersecting in the experimental well.  Observations should
be made on the natural level of the ground water before pump-
ing is begun ; and the pumping is best conducted  by keeping the
level of the water in the well at a constant distance  below the
natural level of the ground water, or below the level of the water
in the  pond or stream.   Although  absolute  equilibrium cannot
be established for  a considerable  time, unless the water  comes
very freely, and in the absence of rain, sufficient  indications can
be obtained to  form judgment, within limits, as to the probable
yield of the well.  In locating a gallery or elongated basin, refer-
ence will be had to  the  direction of the  greatest movement  of
the ground water, which  is sometimes in the direction of the flow
of the visible stream and sometimes at right angles to it.
   A preliminary examination with reference to a future supply
should include a careful survey of the entire drainage area, and
in all  cases the preliminary  examinations should be made  by
those  conversant with the  matter, as there is great liability to
overestimate the probable yield of water.  As a rule, the amount
obtained from any such well is greater at first, as  it requires time
to drain out the water naturally occupying the  territory  which
hereafter is to flow into the well.  On the other  hand, the effect
of the  draught  of water toward a single  point is to  open chan-
nels in the porous  material  so that in  some cases  the yield
* Proc. Inst. Civ. Eng. Gr. Br., lv, p. 257. 
EXAMINATION OF  GROUND WATER.
123
 increases with time.  Besides an assurance  that the quantity of
 water obtainable is and will be sufficient, it is necessary to know
 that the water is satisfactory in quality.   As far as the character
 of the water is concerned, it is  in New England generally good
 when sufficiently abundant ; it is almost always harder than  the
 river water, but  in most localities this difference in hardness is
 small, although appreciable.   In limestone regions, however, the
 ground water  is often so hard as to be unsuited for use ; and
 sometimes the presence  of  streaks or beds of clay or of ochre
 makes it impossible to obtain clear water.
   The absence of such injurious deposits should be ascertained,
 not only at the point at which it is proposed to locate the actual
 well or gallery, but also  in  the immediate neighborhood, espe-
 cially in the direction  in which the gallery is likely  to  be ex-
 tended or where additional wells may be sunk.
   Leipzig, in Germany, has had a ground-water supply since
 1866.  The water, which was of good quality, proved insufficient
 for the wants of the city, and the supply was increased (1871-72)
 by the construction of an additional collecting gallery.   Appar-
 ently the work was done without sufficient preliminary examina-
 tion,  for the works were scarcely  opened  before trouble was
 experienced, and it was found  that  the locality into which  the
 gallery had been extended was generally unsuitable.  There was,
 however, one peculiar  and  instructive difficulty.  The gravel of
 the deposit in which the gallery was located  contained—as grav-
 els frequently do—oxide of iron.  This ordinarily would give no
 trouble, but the  gallery intersected an old river-bed containing
 many partially decayed stumps and other organic matter which,
 in the presence of water, reduced the oxide  of iron to the pro-
 toxide condition, forming soluble protosalts of iron.  These com-
 pounds dissolving in the ground water, found their way into the
 collecting gallery in large quantity.  As soon  as these  soluble
 protosalts  of iron come into contact with the air they are oxi-
 dized, and  a  deposit of the red hydrated oxide  is formed.  In
 Leipzig  the  oxidation generally  took place before the water
 reached the consumers, and the complaint was  with reference to
 the muddy, red appearance of the water when drawn; this was
 easily overcome by filtration.  Sometimes, however, the water
reached  the consumers  before  the  oxidation  was complete, in
which case the  filtered water tasted  " like ink," and on  standing 
124
WATER SUPPLY.
deposited  a further quantity of  a red sediment.*  It  may be
stated that the remedy in this case consisted in  seeking a  new
supply in a more favorable locality.
   As we have seen, even where a well or gallery  is located near
a stream or pond, the  proportion  of water received  from the
visible stream or pond is usually  small;  therefore, to obtain in-
formation as to the character of the water to be obtained, it  is
much more  important to examine the  ground water than the
water of the river.  The examination of the latter should not,
however, be  neglected, and  it would  scarcely  ever,  if  ever, be
advisable to locate " natural filtration " works on  the banks of a
stream which was seriously polluted.
   Further, although  there  is  less liability to  pollution than  in
the  case of small  shallow  wells sunk near dwellings, slaughter
houses,  factories,  or  stables,  it must  be remembered  that the
ground water is fed by the percolation into it of the atmospheric
water, and that it is possible to pollute even a large body of water.
This fact should be taken into  account in choosing a locality for
the collecting wells.
TABLE XVII.—Examination of Ground Water.

       [Results expressed in Parts per 100,000.]
Locality.
Aver, Mass, 1880................................
Newton, Mass., basin near Charles River, 1877.
Taunton, Mass., basin, Aug., 1877.............,
   "    "   river,  "   "  ..............

Waltham, Mass., basin, Dec, 1873..............
   "    "   river,  "   "  ........___

Lowell, Mass., gallery, Jan., 1874___..........
  "    "  river,  "   "..............

Cambridge, Mass., gallery, Dec, 18-6..........
    "      "   pond,    "  " ..........

Chautauqua, N. Y., filter chamber..............
    "     Lake ...........................

Indianapolis, Ind , well,      1880...........
    "     "  White River, 4k  ___.......
oi Q 13 0 (A J $ 0 H	< z 0 s s <	0. p n * •J 2 «	w z 2 0 -1 5 U	
3-3	0.008	0.008	0.1	
3-9	0.	0.002	0	3
5-6	0.009	0.010		
5-8	0.005	0.021		
6.5 5-7	0.005 0.006	0.006 0.016	0 0	4 4
6.4	0.006	0.003	0	3
4-5	0.005	0.010	0	2
18.6	0.080	0.005	3	1
14.0	0.070	0.016	1	7
10.2 7.0	0. O.OOI	0.005 0.006	0	7 8
34.o	0.003		0	°5
29.0	0.005		0	2
Authority.
W. R. Nichols
J. M. Merrick
W. R. Nichols
   S. P. Sharpies

  S. A. Lattimore

05 T. C. Van Nuys
   * Hofmann, Dr. Franz :  Die Wasserversorgung zu Leipzig.  Pph. 8vo, pp. 62.
Leipzig, 1877. 
EXAMINATION OF GROUND  WATER.           125
     In Table XVII are given the results of the partial analyses
 of some ground-water supplies, together, in most cases, with the
 analysis of the neighboring pond or stream.   The chemical ex-
 amination of a water under discussion  directs itself, mainly, to
 proving the freedom  from organic matter and other signs of pol-
 lution, and to ascertaining that the hardness is not excessive.
     In this connection we may mention a peculiar trouble which
 has occurred at several foreign water works.'*
     Since September, 1877, a portion of  the Berlin water supply
 has been taken from the neighborhood of the "Tegeler See," by
 means of a series or line  of 23 wells running parallel with the
 shore of the lake.
    Shortly after the introduction of the water, complaints arose
 as to its quality, and investigation  proved the difficulty to be
 twofold.  It is frequently noticed that water—and especially
, water from a driven well—although apparently clear when first
 drawn, becomes turbid on standing and deposits an ochreous  sedi-
 ment.   This is generally due to the  presence  in solution of the
 protocarbonate or to some organic protosalt of iron, which—on
 exposure to the air—becomes oxidized and changed to an insoluble
 hydrated sesquioxide.   This was the  cause of the trouble which
 occurred at Leipzig, and this was  one of  the difficulties with the
 Tegel ground water, but the microscope showed that the ochre-
 ous sediment which settled from samples of the water, and which
 accumulated in the reservoirs and in the pipes, especially in " dead
 ends," was by no means made  up wholly of amorphous mineral
 matter, but consisted very largely of alga, dead and alive.
    Most noticeable among the alga was the  Crenothrix Kiihni-
 ana {Crenothrixpolyspora, Cohn).  This plant was first  discovered
 by Kiihn in 1852, in the drains of a cultivated field  in Silesia, but
 has since been found in wells in various parts of Europe, and is
probably very widely distributed.
    In Berlin, it  was found in the wells, in  the reservoirs and in
the service pipes, in various stages of development and  decay.
The spores are minute spherical or oblong bodies from one  one-
thousandth to six one-thousandths of a millimeter in diameter.
From these  spores, and by other  means  of  development, the
   * This is abridged from an account of the trouble given by the author in the Jour-
nal of the Franklin Institute, March, 1882. 
126
WATER SUPPLY.
plants grow into comparatively long threads, each  of which on
examination is seen to be made  up of a number of individual
cells, end to end, inclosed eventually in a gelatinous sheath.  The
general  appearance of a mass of  these threads is shown in the
figure, and  the masses are sometimes a centimeter or more in di-
ameter.
              Fig. 24.—Crenothrix Kuhniana.  450 : 1.

   The threads are at  first, like  the spores, transparent  and
colorless, but by the  absorption of iron in some  form or other
they become colored from  olive-green to a  dark brown.  They
eventually, in many cases, become  incrusted with the hydrate of
iron to such  an extent  that their  structure becomes invisible,
but it may be made evident by  dissolving  away the hydrate of
iron by very  dilute  chlorhydric acid.   Under favorable circum-
stances the plants  may develop with great rapidity, and  Pro-
fessor Kiihn speaks of their having frequently stopped up agricul-
tural drain pipes. Also, the pipes in which water is taken from
a well ten meters deep, in the neighborhood of the Plotzensee
near Berlin, have in summer been choked and nearly filled up by
the multiplication of the same organisms.  In the reservoirs and
in the " dead ends " of the service pipes they seemed to accumu- 
EXAMINATION OF GROUND WATER.          127
 late by  growth as  well as  by deposition.   While  the  plants
 develop more rapidly in the warm season, they are found at all
 times of the year in all stages of development.
    It may be remarked, in this connection, that the Crenothrix
 has great vitality; thus, Dr. Zopf  exposed a quantity in water
 out-of-doors from the first  of January to the middle of February.
 The water  was, of  course, frozen, and during the time the tem-
 perature fell as low as to —8°R. (n°F.), but  after being thawed
 out the plants had, in a few weeks, contrary  to  all anticipation,
 revived again or new ones  had grown from the spores.
    The Crenothrix seems to live and develop in the ground itself,
 and in  an  examination  which was made of  the  water from a
 number of wells in different parts of Berlin,  the same plant was
 found in many cases, in one instance at a depth of more than 24
 meters from the surface.
    Whether its presence would be revealed in the preliminary
 examination of a ground water is doubtful, but it ought  certainly
 to show itself if  pumping experiments were carried  on for any
 considerable length of time.
    There seems to  be no remedy for this trouble.   It was found
 possible in  Berlin to filter the water artificially through sand—
 after exposing it to the air—so as to obtain the supply perfectly
 clear; but, of course, the filters were very much fouled, and, on
 account of the difficulty of washing the sand thoroughly and the
 risk that the spores of the  plant would eventually find their way
 into the lower part of the filters and thence into  the service, it
 was thought best by those in charge of the  works to  abandon
 the wells altogether, and  to make use of water taken directly
 from  the lake and filtered in the  usual manner.   The same
 trouble  occurred in  Halle, and it is stated that it was overcome
 by  sinking  other  wells in a  different locality.   In the second
 locality the  water was much harder and free from the Crenothrix ;
 in fact, when it was mixed  with water from the previous source
 it brought about  the extermination of the plant;  hence  it has
 been inferred that the presence of a considerable amount of car-
 bonate of lime is  fatal to the plant, but  this is very doubtful in
view of what follows.
   The  same trouble  has  occurred recently at Lille, in France.
The source of supply is here a subterranean reservoir in marl and
water-bearing chalk lying near the surface. The water comes to 
128
WATER  SUPPLY.
the surface  in actual springs which  originate at no great depth.
The hardness of the water is about 259 (French), and the ex-
amination  made in  1864 showed 44  parts  of  total  solids in
100,000, a large proportion being carbonates of lime and  mag-
nesia.  The water was then considered of good quality,* but for
some time there has been complaint of  a red color and of an un-
pleasant taste and odor.  The matter becoming very serious in
the spring of 1882, led to the  discovery that the trouble  was
mainly due to the Crenothrix.  The previous winter had  been
very dry, and the water level had been lowered about five meters.
The rains of the spring raised the water level, and seem to have
washed out  the plants into the sources of supply; f it is possible
also that contamination of the  overlying soil had  increased the
amount of soluble iron salts which are  necessary  to  the growth
of the Crenothrix.

               The Pollution  of Domestic  Wells.

    In isolated dwellings and in villages and small towns not yet
provided with a public water supply, drinking water must,  as a
rule, be obtained either by collecting the rain water and storing
it in tanks and cisterns, or else by  sinking wells.  On account of
the clearness and nearly uniform temperature of the ground wa-
ter, the latter method is usually preferred when practicable.   In
the majority of cases the location  of the well is dictated simply
by convenience, and it frequently happens that it is in close prox-
imity to a privy, or to cesspools, or to a barn or stable.  The result
is that the well is very liable to  pollution, and, more  often than
not, it is simply a question of  time when the water shall become
unfit for use.  The pollution  of the  well generally takes place
gradually.   The  ground  gradually  becomes  charged with  the
soakage from the privies and manure heaps, and percolating  rain
water carries the  impure  matter into  the ground water from
which the well draws its supply.   In other cases, actual channels
are formed, by which  the foul liquid trickles or flows into the
well itself, or a leaky drain, laid  near the well, may be the source
of the trouble.
   Whatever views may be held of  the effect upon  the human

   * Masquelez : Ville de Lille. Etablissement de la Distribution d'Eau, Paris, 1879.
   f Alf. Giard : Comptes rendus, xcv (1882), 247-249. 
POLLUTION  OF WELLS.
129
system of drinking such water, there is no question whatever as
to the pollution itself, and although the water may appear clear
and bright, and be inoffensive to the senses,  chemical examina-
tion may show that it is highly charged with the products of de-
composition.   Moreover, there are hundreds  of cases on record
where sickness has been coincident with the use of  polluted well
water, and, although  the evidence is of necessity circumstantial
(see Chapter  I), it is too striking  to  be  disregarded.   In  the
present state  of knowledge, it must be  said that the continued
use of a well water proved to be polluted is as unjustifiable as
suicide generally is.
    It is often difficult to persuade the  owner  of  a  polluted well
to  abandon its use.  The water tastes good  and has been used
for years without  producing any bad effects.   Meanwhile, how-
ever, in these  years the neighborhood has become thickly settled,
the various possible  sources of  contamination  have increased,
and the whole ground water of the region has felt the effect.  At
the same time, in urging the abandonment of the well, one cannot
say that, in spite of the pollution, it may not be used for years
more without noticeable ill effects.   Under what conditions the
water may become injurious, and when, no one can  say.
    It is also difficult to realize the distance from which the pol-
lution may come.   Until the water of the well becomes contam-
inated to a very great extent,  the taste gives no evidence of con-
tamination, but occasionally accidental evidence is furnished of
the distance  from which communication with  the well may
exist.
    An  illustration of this point, and  a further illustration of
certain chemical changes which have  been  already alluded to
is  the following.  In Wernigerode,  Germany,*  a  certain  well
which  had always  been nearly free from iron,  suddenly began to
furnish a chalybeate water.   Clear when drawn, the water soon
became turbid, and deposited  on standing a copious ochrey sedi-
ment.   It was finally discovered  that this sudden change was due
to the emptying of several casks of spoiled beer into the ground
at a distance of some 35 meters (115 feet).   The  organic matter
thus introduced into the ground acted as a  reducing agent on
the ferric oxide contained in the soil, and the iron, dissolved as

      * Wockowitz, E.: Wernigerode's Trinkwasser.  Wernigerode, 1873.
         9 
130
WATER  SUPPLY.
protocarbonate, found its way into the body of water from which
the well was supplied.
    In  some places,  owing to the  very nature of the locality,
shallow wells  are  to be rejected  as  sources  of supply.  Thus,
Dr. Smart *  says,  with reference to New Orleans: " The well
waters of  New Orleans are unfit  for use.  They are but little
less impure than the sewage water carried  off by  the drainage
canals, yet they are  reported as being  employed for family use,
in bakeries, and for stock, especially in summer, when the cistern
supply fails.    The  site of the city is waterlogged  to within  a
few feet of the surface.   One well, on Chestnut street, the least
impure of  those examined, is only 10 feet  deep, and  contains 7
feet of water.  The saturated soil  is of great depth, and  the
ground water  is  practically stagnant.  The  filtration into  the
wells is insufficient even to  free the water from turbidity.   Or-
ganic  matter is unaffected by the  process.  The water contains
alkaline carbonates,  chlorides, large amounts  of free  ammonia,
but no nitrates or even nitrites.   In four  wells examined, the
ammonia from  organic  matter amounted to  0.039,  0.041, 0.044,
0.080 part ; while in the sewage from the Orleans canal it only
reached 0.120 part.   These samples are so  impure  that the use
of well water in New Orleans should be interdicted.!  Even care-
ful filtration should not be relied on to purify such waters.  Fil-
tration is not a process  by which dangerous waters  may be util-
ized, but  simply  a  guard against  the possibility of  danger in
doubtful waters."
   We have thus far spoken only of wells  which are  sunk  into
the ground water.   These are the most common, but many wells
are sunk into a more or less compact  rock, and the water comes
through fissures in the rock.  In such cases  it  is often difficult to
tell where  the  water does come from, and the well is liable to
contamination  from distant sources.  The  pollution is liable to
be even more serious than in wells sunk into  the ground water,
because the contaminating  substances carried by the stream of
water do not have the same opportunity to be oxidized as they
do when the water passes with comparative slowness through  a
body of sand or gravel.
* Bulletin National Board of Health, April 17, 1880.
t Such use is now prohibited by law, 1883. 
EXAMINATION OF WELL WATERS.            131
    Of the well waters which are submitted to chemical examina-
tion a limited number show by the absence of  ammonia, nitrog-
eneous organic  matter,  and chlorides in appreciable quantity,
that they are free from all contamination; on the other hand, a
considerable proportion (not, however, one-half according to the
experience of  the author) may be condemned  at  once ; the  re-
mainder can only be considered doubtful or  suspicious.  In the
cases of those  suspicious wells which cannot be absolutely con-
demned, the proper course is to have, for a time at least, some-
what frequent examinations made  of the water to  see whether
the impurity is on the increase.   For this  particular purpose, it
is usually sufficient to follow a single ingredient, say, for exam-
ple, the chlorine existing as chlorides.  If the amount of chlorine
increases to any considerable extent, the source of impurity
should be ascertained and the water be protected therefrom, if
possible, or  else be rejected from  use.
    It  may  be  said, in a general way,  that a  good  well water
should  not  contain  over 0.005  Pai"t °f ammonia  in  100,000, or
over 0.010 part " albuminoid ammonia," and, in most places, not
over 1.0 part of chlorine (as  chlorides).  The amount of solid
matter  in solution  depends necessarily upon  the locality, and
what might  be a reasonable amount in one  region would be very
abnormal in another. The presence of nitrates  is also suspicious.
but, unless the quantity is very considerable, cannot alone con-
demn the water.  Dr. Charles Smart, U.  S. A.,  accepts 0.010
albuminoid ammonia in 100,000 as suspicious, and 0.015 as a limit
in the case of well waters " in the  denser settlements, and in every
case where an animal origin to the organic matter is indicated by
careful survey or  chemical analysis."
    In the case of doubtful waters, the greatest satisfaction may
be obtained when it is possible  to find  in  the same immediate
neighborhood a well of whose freedom from contamination there
can be  no doubt.   The comparison of the waters of the two
wells will probably enable  one to decide the question as to the
contamination  of the first well.  The  next  most satisfactory
course of procedure is to throw a quantity of salt (or brine) into
the various cesspools, drains, etc., and to determine at frequent
intervals the amount of  chlorine (as chlorides) in the water of
the well.  As instances in which this method was used with good
results,  the two following may suffice: 
132
WATER SUPPLY.
   In No. I, the  well was located ioo  feet from the privy ; a
bushel of coarse salt was put into the privy-vault October 24, and
a bushel  of fine salt on October  31.   This caused an  evident
increase of the amount of chlorides in the well, as appears from
the figures.   In case No. II, two bushels of salt were put into a
cesspool which was 75 feet from  the well.  A sample of water
was  then taken and afterward at  intervals of  three days.   The
effect on the well water was not  as marked  as   in No. I, but
the results were confirmed by a subsequent examination of the
locality:
Date of Examination.	as Parts in
October 17	3-3
26	3-9
29	3-9
November 2	4.0
5	4.4
8	3-5
13	3-4
17	3-4
20	3-3
23	3-1
II.	II.
No. of Sample.	Chlorine
I	1.4
5	1-5
3	1.6
4	1-7
5	1-7
6	1.9
7	2.6
8	2.0
9	2.0
10	I.g
   In  Table XXIII are  brought  together the  results of the
examination of a few well waters from various localities.   The
table might be extended to an  indefinite length, as the reports
of boards  of health  and water committees would, in almost
every case, contribute to the list.
TABLE XVIII.—Examination of Well Water.
        [Results expressed in Parts in 100,000.]
Locality.
Sauffus, Mass.........
  v>   Another......
Williamstown. Mass..
    "    Another
    "    Another
North Adams, Mass..
Gloucester, Mass......
Watertown, N. Y___
Croton Falls, N. Y...
Lockport, N. Y.....
Southampton, L. I.. .
Q		Q			
0	<	2 <	H		
	z 0 s	S z, s 0 3 s	S X 0	Quality.	Authority.
0	s	<<	X		
H	<		u		
7 3	0.001	0,002	I.I	Good.	W. R. Nichols.
21.0	0.002	0.002	3 1	Suspicious	
19-3	0.002	0.009	i-7	4k	11
63.1	0.006	0.015	I0.2	Polluted.	"
112.1	0.005	0.013	40.0	"	"
3i-7	0.014	0.009	2.2	"	»»
68.6	0.230	0.029	9-5	"	"
37-4	0.002	0.005	9-3	Good.	E. Waller.
13.2	0	0	0.8	fc*	n
96.8	0.001	O.007	8.9	Doubtful.	i>
45.0	0.006	0.018	4.0	Bad.	"
 
CHAPTER  VII.
        DEEP  SEATED WATER AS A SOURCE OF SUPPLY.

    While a portion of the rainfall which soaks into the ground
 soon encounters an impervious stratum, above  which it collects
 to form the ground water of the locality, much  of the water pre-
 cipitated from the atmosphere falls upon the edges of upturned
 rocky strata, or upon rock deposits which are either themselves
 porous or so fissured that they afford a more or less free passage
 for water.  When the peryious stratum has an  outcrop at some
 lower level, the water may issue in the form of springs, more or
 less copious.  Where the course of the water has not been too long,
 and it has not, consequently, taken up a large amount of mineral
 matter, such springs furnish one of the best sources of drinking
 water, although the water is very often, in fact usually, less well-
 suited for technical purposes, on account of  its hardness.  The
 advantage of spring water over surface water for drinking is con-
 sidered by some so great as to justify the incurring of very con-
 siderable expense in order to procure it.  Thus, the city of Vienna
 constructed extensive water works for the sake of bringing water
 from springs which are sixty miles distant.

                        Artesian Wells.

   When the water precipitated from the atmosphere is absorbed
 by a pervious stratum which is situated between two impervious
 strata, the water may exist under considerable hydrostatic press-
 ure.   The occurrence of a " fault " in the strata may allow the
 water to rise to the surface of the ground as springs, but often
 the water can be utilized only by sinking or boring artesian wells.
   An artesian well is a well which is  sunk or bored  through an
 impervious  stratum so as to reach a water-bearing stratum in
which the water is under hydrostatic pressure;  so that, as soon
as the well  is opened, it rises  through the impervious stratum
and often to, or higher than, the surface of the ground.   Arte- 
134
WATER  SUPPLY.
sian wells may, therefore, be regarded as artificially opened springs.
The term artesian is frequently applied to non-flowing deep wells,
but, while the question of flowing  or  non-flowing may be unes-
sential,  the term is improperly applied to wells, however deep,
                              when the water is taken from the
                              deposit into which  the well is
                              bored  or  sunk, and  where  the
                              water  collects from  the fissures
                              and cavities of  the  rock  itself.
                              Thus, in England, there are many
                              deep wells in the chalk or in the
                              new red sandstone which collect
                              and utilize water from the chalk
or from the sandstone itself, and which are not properly to be char-
acterized as artesian.  In this country, driven wells are often called
artesian wells, and they may be properly so designated if they pass
through a stratum of clay, so that  the water rises from an underly-
ing deposit not in communication with the ground or surface water
of the same locality : driven wells,  however, as we have already
seen, often utilize simply the ground water where they are driven.
   Although, within  modern times,  improvements  have been
made in the methods and apparatus employed  for  boring wells,
wells of this description are  of great antiquity.  They are found
in China, and many such  wells have existed for a long  time in
North Africa, in the oases of the Sahara.   Here, until recently,
they were excavated by hand, the earth and other material being
drawn up in baskets.  Finally, a thin stratum of rock was reached
beneath which experience had shown that water existed.  This
rock stratum was cautiously perforated, and as soon as it was
pierced  the  workman  was drawn up  rapidly—and  not  always
safely—as he was sometimes overtaken  by the rush of water.
The French in  the province of  Constantine (Algeria), between
the years 1856 and 1878, bored over  400 wells.  The flowing wells
numbered 158, with an average depth of 85.5 meters; the tem-
perature of the water was generally  betwen 21° C. and 260 C, and
the total solids between 300 and 600 parts in 100,000.'*
   There are a great many artesian wells in various parts of the
   * Les Forages arte'siens de la province de Constantine (Algerie).  Resume^des
Travaux executes de 1856 a 1878.  Par M. Jus. 8vo,  pp. 97.  Paris, Imprimerie
Nationale, 1878. 
ARTESIAN WELLS.
135
United States.  Thus, Professor Winchell, in 1856,* mentions as
many  as  74 such wells in a single and somewhat circumscribed
region of middle Alabama, and, of late years, many wells  have
been sunk in the southwestern part of the country with favora-
ble results.
    The sinking of artesian wells is attended with  great uncer-
tainty as regards both the quality and the quantity of the water
to be obtained, and many wells have been sunk which have failed
to reach water at all, or from which only water unfit for any do-
mestic use has been obtainable.  To  judge of the probability of
success in sinking  a well  in a new locality, a knowledge of the
geological character  of the underlying strata is essential.  At
Charleston, S. C, where are several successful artesian wells, f the
possibility of obtaining such wells was inferred from  a knowledge
of the geology of the region.  More than 100 miles from the city,
starting from Augusta, Ga., and proceeding northeastwardly, a
granite ridge rises to  the surface of the earth, exposed to view in
favorable  positions, elsewhere  covered with superficial drift sands
and clays.   The line may be followed northward through North
Carolina, Virginia, and Maryland.  On the broad surface of this
granite ridge, and on its seaward slope, the sands drink in the
rain water that falls.  The streams  from the up country that
cross the  ridge  may also supply  their quota.   The water thus
imbibed sinks down by the force of gravity, ever seeking the low-
est attainable position.  Now, the tertiary beds of the Charles-
ton Basin, the cretaceous beds under them, and any other sedi-
mentary beds beneath the cretaceous, must rest  against this
eastern slope of the granite ridge, and their sandy layers must
drink in the water filtering through the sands.  As all of these beds
have a gentle slope toward the coast,  the water will follow them
down  in their course.   These  formations,  no doubt, continue
their course  under water for  many miles, and, indeed,  there is
evidence that the water contained  in them finds a discharge into
the sea.  To this cause are attributed the springs of fresh water
that have  been observed to rise, bubbling up  at times in notable
quantity through the salt water at points along the coast, fifteen or
twenty miles from the shore.  Moreover, in all the deep  wells in
* Proc. Amer. Assoc, x (1857), p. 83.
f Municipal Report of the City of Charleston, S. C.  Artesian Wells, 1881. 
I36
WATER SUPPLY.
Charleston, varying  from 60 to 1,260 feet in depth, the level  or
head of water in the pipes has  been observed to oscillate at tidal
intervals to an extent varying  from 4 to 6 inches.  The explana-
tion is simple.  In  issuing from its  natural vent under the sea
the  fresh water must lift  the  column of salt water above, the
weight of which acts as an obstruction.   When the tide at sea
is high, this column  is greater than it was at low tide.   The  con-
sequence is a diminution of the escape of water by that channel,
and  a compensating increase  of   the  discharge through other
channels not so obstructed, and an increase in the head of water
in the wells.*
   One disadvantage of sinking artesian wells for town supply
is the great  uncertainty as to the  quality of the water,  and
the  fact  that water  from  considerable depths is  often of ele-
vated temperature, and therefore not fit to  drink unless cooled.
Moreover,  the water is apt to be  charged with a large amount
of mineral matter derived from the strata through which it has
flowed or percolated, or  in contact with which it has  remained
for  a long period  of time.   The widely-known well at Gre-
nelle, Paris, which is about 1,800 feet deep, has a temperature  of
270  C. (8o°.6 F.), and contains  only about  14 parts in 100,000  of
dissolved solids, whereas a well in St. Louis, Missouri, sunk  at
the sugar refinery of Belcher and Brothers to a depth of over
2,000 feet, and at an expense of $10,000, furnishes  about 75 gal-
lons per minute of water emitting a strong odor of sulphuretted
hydrogen,  and  containing 879.1 parts  of dissolved  matter  in
100,000 parts; this water is entirely useless for the purposes  of
the refinery or for domestic use.  As already stated, the artesian
wells in  Algeria contain  from 300  to 600 parts of  dissolved
solids in  100,000 parts of water, and would, in most localities, be
at once rejected even for purposes of  irrigation.  In the absence,
however, of  better  water, such wells  as these are regarded  as
godsends by the inhabitants.
   The fact  of a considerable amount of dissolved solids does
not  necessarily  prove that an artesian water is unfit for  use,
although usually the salts present  are objectionable in character.
Sometimes the dissolved matter, in the absence of lime, magne-
  * The above statement is  condensed from the Charleston Municipal Report
already cited. 
ARTESIAN WELLS.
137
 sia and sulphates, may be unobjectionable in character, although
 the large amount present may be undesirable.  For example, the
 water of the Wentworth Street artesian well in Charleston, S. C,
 which contains  273.66 parts of total  solids in 100,000, has been
 used  for years.  In this case  the  dissolved matter  is  almost
 entirely common salt and carbonate of soda, and  the use of  the
 water is held to be beneficial  in dyspepsia and kindred diseases.
 The water  of  the more  recent Citadel Green  well contains
 only 111.55 parts in  100,000 of solid matter, likewise  consisting
 mainly of  these two  salts.  The water is considered wholesome
 as  a drink, and,  for washing, the presence of  the carbonate of
 soda makes it an excellent water; the principal objection found
 to  it is that the carbonate  of  soda  gives to rice, hominy and
 other farinaceous articles cooked in it a light golden tinge, owing
 to the action of the carbonate of soda on  the starch in such  arti-
 cles.  In the laundry, also, it cannot be used in the mixing of  the
 starch for the same reason.
    It may be here noted that the quantity of water obtained from
 an artesian well is  often seriously diminished by the sinking of
 other wells into the same water-bearing stratum.  This has been
 the experience in many localities.  With reference to wells in the
 neighborhood of London, Eng., De Ranee says:
    " The  outcrop of the lower London  tertiaries is about 100
 feet above the  Thames, whilst their depth below it varies from
 200  to  300  feet,  the only notch in the rim of the  basin being
 the valley of the Thames at  Deptford and Greenwich,  where
 the outcrop is 100 feet lower than the remainder of  the margin
 of the basin ; the sectional area  of the  depressed  portion being
 much less  than the elevated  portion, far less water can escape
 than can be  absorbed  by the  sands, which are practically water-
 logged by the overlying, impermeable clay, through which borings
 were carried to a depth of 80 to 140 feet at the beginning of the
 century; at that time the liberated water flowed up  the bore-
 holes, and rose permanently above the level of the Thames until
 the supply was over-pumped,  and it has  fallen to 70 feet below
 Trinity high-water mark.  To supply the deficiency,  most of the
artesian wells in London have been carried down to the chalk
beneath, to intercept  the water which circulates freely  in the  fis-
sures and lines of joints.   The  level to which water will rise is
steadily decreasing." 
138
WATER SUPPLY.
                         Deep  Wells.
   In certain geological formations, the nature of which does not
admit  of  the  construction of artesian wells  proper, water  may
often be obtained  in  large quantities by sinking shafts, in which
the water collects and from which it may be raised to the surface
by pumps.  Horizontal tunnels may be carried from the shaft,  at
one or more levels, so as to intercept the water flowing through
the fissures or along the planes of stratification.   Sometimes, in-
deed, the water may be obtained solely by means  of a horizontal
tunnel, the opening being made in the face of a bluff.   Thus,
Dubuque, Iowa, is supplied from a tunnel or adit penetrating the
bluffs and extending for about a mile  in length at a depth, from
the surface of  the ground, of from ioo to 200  feet.
   Deep wells are used  as  sources of  public supply, to some
extent, but the greater number the world over are sunk or bored
for private establishments, notably for  breweries.  It is stated
that in the city  of New York  there are as many  as 40 wells
on Manhattan Island, although some of them  are not now in use.
Nearly one-half this number are owned by breweries.   The wells
vary in depth  from 26 to  2,000 feet.  Eighteen are 500  feet  or
more in depth.   The diameter also varies, being from 2\ to  10
inches,  although  the  majority are 6 or 6^ inches.   The capacity
of the wells ranges from  2,000  gallons to 126,000 gallons in  24
hours;  and  the temperature of the water, so far as noted, is
between 500 and 590 F.  As might be expected from the geolog-
ical  formation of  the island, the wells are, in most cases, bored
in gneiss and mica schist.*
   In England, where deep wells are used to a considerable ex-
tent as sources of town supply, the water-bearing  capacity of the
various geological formations, and the character of the water to
be obtained therefrom, has probably been studied more carefully
than elsewhere.f  Of the water supply of Liverpool, 5,500,000
(imperial) gallons are daily pumped from the wells in the  new red
sandstone, and London receives daily some 8,000,000  (imperial)
gallons from deep wells in the chalk.
   * Sanitary Engineer, October 12, 1882.
   f See Sixth  Report of Rivers Pollution Commission ; also, the various (annual)
reports of the Underground Water Committee of the British Association ; also, De
Ranee, Water Supply of England and Wales. 
DEEP WELLS.
139
   Fig. 26 shows a well which is sunk  in the new red sandstone,
at Whiston, England.*  Two wells, each 9 feet in diameter and 12
feet apart, were sunk to a depth of 135 feet and then continued
to a depth of 225 feet as a single well, 30 feet long and 9 feet
broad.  The bottom of the well is 25 feet below mean sea level,
and when first  sunk, supplied some 400,000 gallons  in 24 hours,
with a depth of about 9 feet of water  in the well.  The manner
in which the well cuts the strata of the sandstone is evident from
the figure, the water having a natural tendency to  flow along the
planes of stratification toward the fault shown at the left, which
presents a barrier to  its farther progress.  The works were  sub-
sequently extended by sinking and boring the auxiliary well  in
the right of the figure, and connecting the two wells by means
of a tunnel.  The supply obtained from the combined wells, was,
in 1876, about 900,000 (imperial) gallons in 24 hours.
   The capacity of a rock for storing and absorbing water varies
with its texture and  character; and when, after long continued
rains, the rock has become  fully saturated, no more water can be
absorbed, and all additional supplies pass off as floods, as abso-
lutely as if the precipitation took place  on an  impermeable for-
mation.   Many rocks thus contain, in their natural and undis-
turbed condition, water which was derived from the  atmosphere
long ago, and in some  cases  the rocks may contain saline solutions
which have filled  their pores from the time of their  formation.f
When a well is sunk into such a deposit, the water may be grad-
ually  forced  out  by the pressure of the water accumulated  in
other parts of the same stratum, or in communicating strata, but
it may take a very long time to exhaust the subterranean reser-
voir.  In some cases, near the sea, there may be communication
with the ocean, which may thus produce the hydrostatic pressure,
but which may not contribute by its waters directly, or at least
not for a long time after the well is opened.   Some deep wells
near the sea gradually become more brackish, probably  from the
fact that the purer water which originally filled the pores of the
rocks, and perhaps subterranean reservoirs, is gradually exhausted,
and other water—in this case sea water—comes in  to replace it.
   Some idea of  the vast amount of water stored below the sur
* Proc. Inst. Civ. Eng. Gr. Britain, xlix (1877), p. 221.
f See Hunt's Chemical and Geological Essays, p. 104 and elsewhere. 
SECTION  SHOWING .THE. POSITION OF THE STRATA PIERCED  BY THE  WELLS. TUNNEL, AND SORE  HOLES.
                                        ScaU of Yards.
                   &.,f;,,,T,.......«.,„• 36  i ,V........£-----■------'------■-----------*°

                             FlG. 26.—WATER WORKS  AT  WHISTON, ENGLAND. 
DEEP WELLS.
I4I
 face of the ground may be obtained from the following extract
 (De Ranee):
    " In the Thames and east coast district are not less than 4,000
 square miles of pervious cretaceous rocks, receiving not less than
 5  inches  of rain annually, or  a daily absorption of 800,000,000
 gallons.  It is readily understood with these figures, how the dry
 weather flow of the  Thames is kept up by chalk springs; one-
 fifth of the yield is sufficient for 4,000,000 people, and taking the
 oolite supply, the total volume of water absorbed by underground
 sources in the Thames and east coast river basins may be taken as
 1,125,000,000  gallons—a supply equal to the wants of 22,000,000
 people, or nearly that of the total  inhabitants  of England, sup-
 posing that the whole of the 5 inches of rainfall absorbed could
 be pumped up."
    It  is, of course, impossible  to utilize all  the water actually
 contained in any rock.   From a compact rock like chalk or lime-
 stone, a portion of the water is furnished by cracks and fissures,
 and this is readily given up ; another portion passes through the
 rock itself, and although the water may be received and absorbed
 with great rapidity, it is delivered with  extreme slowness, and a
 struggle is maintained, as it were, between capillarity and gravity.
    Baldwin Latham * has called attention to the influence of the
 barometric pressure on the volume of water discharged by springs
 (or yielded by  deep wells).  When the barometer falls, the  air
 confined in the fissures of the rocks tends to expand and force out
 the water, and the volume of the springs increases; when there
 is  a rise in the barometer, there is a diminution  of  the flow.   A
 more or less  marked  coincidence between barometric  changes
 and variations in the amount  of water discharged by mineral
 springs was noticed  long ago,  and various  explanations have
 been offered to account for the phenomenon.f
   When a well is opened in a water-bearing rock, the level  of
 the water, or plane of  saturation, will be found to vary  within
 certain limits, being governed by the amount of rainfall absorbed.
This level, after extensive pumping, is artificially and locally
lowered, but, on the cessation of pumping, the  original level is
restored by a  sufficient interval  of rest, provided the volume
   " Nature, September, 1881.
   f See, for example, Alois Novvak : Ueber die barometrischen Ergiebigkeits-
Schwankungen der Quellen in Allgemeinem. Prag, 1880. 
142
WATER  SUPPLY.
 abstracted  annually is not more than is supplied by the rainfall.
 If the demand upon  a deep well is greater than the supply re-
 ceived directly or indirectly from the  rainfall, the well will show
 signs of exhaustion ;  the  supply may, however, be  kept  up by
 deepening  the well, that  is, by  taking the  water  from a lower
 level.   Many wells gradually furnish less and less water, because
 in the beginning there was a quantity of water stored in the rock,
 which has  gradually  become exhausted.   On  the  other hand,
 some wells furnish a  supply  increasing in abundance, owing to
 the fact that the passages through which the water comes become
 less obstructed and of larger size.  Thus, according to the Rivers
 Pollution Commission, every 1,000,000  (imp.)  gallons of water
 drawn from the chalk carries with it,  in solution, on an average
 11 tons of chalk through which it has  percolated, causing an ad-
 ditional storage room for 110 gallons of water;  so that the yield
 of a well draining a given  area in the chalk, other things being
 equal, ought to gradually  increase until the maximum limit of
 permeability is reached.  As a further example  of the same
 thing,  it may be mentioned that, during the construction of the
 tunnel at  the Whiston water works, upward of 350 tons of sand
 were in a few years washed from the  fissures of the rocks, thus
 increasing the storage  capacity of the rock.

    Characteristics and Examination of Deep-seated  Water.

    The questions of the amount of water to be obtained from
 springs and  deep wells, and of the probability of procuring water
 by means of artesian wells  in any given locality are questions for
 the engineer and geologist.   The  fact that  all  such waters are
 liable to contain an excess of mineral matter has been  sufficiently
 noticed: the chemical examination  concerns itself mainly with
 the  amount and  nature of  the dissolved salts.  These deep
 waters are characterized, in general, by an  absence  of organic
 matter, but  that even  deep wells  are liable to pollution may be
 easily realized  by an inspection of Figure 26.  It is very evident
 that any polluting matters  in the  soil might easily find their way
 into the  well, being  carried downward by  the water passing
 along the planes of stratification.  In the case of  the water works
at Whiston,  all  the  wells in the  immediate neighborhood were
affected, most  of  them losing their water altogether.  This in- 
DEEP WELLS.
143
 fluence was felt at least  i£ miles to the southeast and more than
 a mile  to  the south.   Where the  water flows  underground
 through cracks and fissures the polluting substances do not have
 the opportunity to become oxidized  and harmless, as when the
 water passes  slowly  through a gravel deposit.   Mr.  Baldwin
 Latham has  connected  the periodic  outbreaks of  fever  in the
 parish of Croydon, England, with the  intermittent  appearance
 of springs called the Bourne.   The water which is reabsorbed by
 the chalk lower down,  is supposed  to carry  the objectionable
 substances to the wells  in  the center of the old town.  When
 the springs are low and the Bourne begins to run, after a sudden
 and copious rainfall, the water line under the town  is elevated
 and an  outbreak of  enteric fever results.  Even with  artesian
 wells there is not perfect security, for many  such wells—espe-
 cially when first opened—throw out fragments  of vegetable sub-
 stances,  and  even living fish and other small aquatic animals,
 showing that  they must have a more or less direct  communica-
 tion with the surface.
    Signs of pollution in such  waters  must be sought mainly in
 the  " organic matter"  as variously determined : chlorides are
 often present  in considerable amount, but are not  evidence of
 impurity; nitrogen in  the form of nitrites and nitrates is also
 often present  in  notable quantity in  water of  deep wells, espe-
 cially in the chalk, and  is no sign of  contamination; ammonia
 may also be allowed  in  amounts which would be suspicious in
 shallow wells.
   While the artesian wells often furnish water the temperature
 of which is objectionably high, the water of many springs and of
 ordinary deep wells is  usually of nearly  uniform and of compar-
 atively low  temperature.  In fact, the sinking of deep  wells in
 connection with breweries is partly due to the fancied necessity
 for hard  water in brewing certain  kinds of beer, and partly  to
 furnish an abundance of  cold water for cooling purposes.
   It is a curious fact that the  hard water from springs and deep
wells, though  clear and bright when first  obtained, becomes
 covered with a confervoid growth when exposed to the sunlight
in open reservoirs, and the tubes of some artesian wells become
lined with  a growth  of algae.  If  it  is necessary to store the
water from deep wells, this should be done in covered reservoirs ;
this is, of course, desirable also as a means of avoiding elevation 
144
WATER SUPPLY
of temperature in summer if the water remains in the reservoir

for any considerable time.
   Table XIX contains some  details with reference to artesian

       TABLE  XIX.—Examination of Artesian and Deep Wells.
Locality.
       Artesian Wells.
Grenelle, Paris................
Passy, Paris ..................
Boston, Mass..................
Chicago, 111...................
Louisville, Ky., Dupont's Well
St. Louis, Mo................
   "   Mo., Asylum Well..
Charleston, S. C, Wentworth Street
   "     "   Citadel Green__
   "     "   Chisholm Mill___
Coosaw, S. C.......................
         Deep Wells.
Birkenhead, Eng....................
Birmingham, Eng..................
    "    Another..............
Bradford, Eng.....................
Brighton, Eng.....................
Liverpool, Bootle Well.............
London, Trafalgar Square.........
Jersey City, N. J., Secaucus Works
Newark, N. J., Celluloid Works___
   "■    "   Lister Bros ........
Paterson, N. J., Burton Brewing Co
h	z		
W fa	k a		a
			
55 X h W	h x a < 0 a K Z S S zo SuQ	[/> z u «> 9 2 h X « 5 0 <0h s	°5« t/J in 8 j h 8
Q	H	ffi	H
i,806	27		14.2
1,914	28		14.1
i,75°			1878.7
700	14		
2,086	24.3		1570.0
2,199	23		879.1
3.843	4°-5		
1,260	3°-7		273.7
1,970	37-5		m.6
425			369-7
760			82.7
527		5-7	14.2
300	10.2	15.8	3i-3
400	10.8	IS-1	19.3
360	12.8	14.1	55-4
1,285	9.9	4-4	35-4
312	10.4	12.6	34-4
!«!		5-9	83-4
600			117.7
250			213.0
61 s	13.0		262.0
200			20.6
Authority.
Peligot, 1857.
Poggiale & Lambert, 1862.
J. MT Merrick.

J. Lawrence Smith.
A. Litton, M.D.
C. C. Broadhead.
C. U. Shepard, Jr.
S. T. Robinson, Jr.
Wm. Robertson.
F. F. Chisholm.
Rivers Pollution Com.
G. H. Cook, Geol. Rep.
and deep  wells in various localities.   Although  there  are so
many of these wells in the United States, the  author has found
it extremely difficult to obtain reliable information with reference
to the chemical character of the  water.  The depth of the well,
whether the water is  palatable or  undrinkable, how  it  acts to-
ward soap and in steam boilers—these  observations, which do
not require the aid of an expert  or involve additional  expense,
usually complete the stock of available information.  Table  XX
contains the results of more complete analyses obtained  by the
Rivers  Pollution Commission of Great Britain from the  examina-
tion of  a  large number of deep-well waters from various geolo-
gical formations.   In the same  table  also—for  convenience  of
arrangement—are inserted the  results  obtained  by  the  same
commission in  the examination of unpolluted  waters of various
descriptions and from many different  localities in Great Britain.
Table XXI contains results derived from the examination of the
water from wells  and springs in  the different  geological forma-
tions in Bohemia,* the total  number of analyses being about 125.

    * Belohoubek:  Ueberden Einflussder geologischen Verhaltnisse auf die chemische
Beschaffenheit des Quell- und Brunnenwassers. Pph. 8vo, pp. 46.  Prag, 1880. 
EXAMINATION  OF VARIOUS WATERS.
H5
TABLE XX.—Examination of Deep-Well  Waters and of Unpolluted

                      Waters  from  various Sources.

                        [Results expressed in Parts  in 100,000.]
Geological For-
    mation.
   Deep  Wells.
DevonianRocks and
  Millstone Grit___
Coal  Measures.....
Magnesian Lime-
  stone.............
New  Red  Sand-
  stone............
Lias................
Oolites..........
Hast i n g s  Sand,
  Green Sand, and
  Weald Clay...
Chalk...........
Chalk beneath Lon-
  don Clay......
Thanet  Sand and
  Drift..........
Unpolluted Waters.
Class I.
  Rain Water......
Class II.
  Upland Surface
   Water.........
Class III.
  Deep Well Water
Class IV.
  Spring Water....
32.68
83.10!

61.14

30.63
70.98
33.60
45-20
36.88

78.09

53-84
 2-95


 9.67

43-78

28.20
0.068
o. 119

0.076

0.036
0.146
0.037
0.068
0.050

0.093

0.113



0.070


0.322

0.061

0.056
0.012
0.034
0.014
0.027
O.OIO
0.014
0.017

0.028

0.020
0.032

0.018
0.005
0.044
0.003
O.OOI
0.022
0.016
O.OOI
0.002

0.012

O OOI

0 Q
0.294
0.207

1.426

o 717
0.389
0.625
0.196
0.610

0.068

0.116



0.003


0.009

0.495

0.383
  III
J 9,
< o
O H
0.310
0.278

1.456
o 734
0.417
0.654
0.223
0.628

oi35

0.202




o 042


0.042

0.522

0.396
U S
u <
< H
S z
[Tl O
3 <
o s
-* z

CL,
2,671

2,243
6,895
3,73°
6,118
797

,517
 2.70
18.05
2 94
4.42
2.69
5-38
2.76
15.02

 6.32
42  0.82
4,743

3,595
1.13

5-"

2.49
Hardness.		
b	a	
rt		
		
		
e	B	"<3
		
	<j	
H	P-	H
8.8	8.6	17.4
15.1	20.6	35-7
16.9	26.9	43-8
7-4	10.5	17.9
21.9	8.2	30.1
13-8	6.8	20.6
16.8	10.5	27-3
21.2	6-5	27-7
9-7	8.7	18.4
14.4	7.6	22.0
0.4	0.5	0.3
i.5	4-3	5-4
15.8	9.2	25 0
11.0	7-5	18.5
195
157
TABLE XXI.—Bohemian Well and Spring Waters.

           [Results expressed in Parts  in 100,000.]
Geological
Formation.
Azoic........

Huronian

Silurian.......

Carboniferous.

Permian.....

Chalk..'.'.'.'.'.'.
Neogen.........
Diluvium and )
Alluvium     ) ''
Results.
Max. and Min.
 Usual Limits.
Max. and Min.
 Usual Limits.
Max. and Min.
 Usual Limits.
Max. and Min.
 Usual Limits.
Max. and Min.
 Usual Limits.
Max. and Min.
 Usual Limits
 Usual Limits.

 Usual Limits.
Total
Solids.
 2.8- 2S.0
 4-6- 14-3
19.8- 55.0
30.5- 55 0
14.5-150.2
66.0-120.0
38.5-374.0


 4-5- 29.7
 6.5-  9.0
 4.0-109.0
2i-5- 75-7
37.0- 49.7

I9-I- 75-5
SuLPHUf:iC
Acid tS03).
0.2-  2.4

i-3-  5-9

2.8- 48.6

2.4-101.6

0.1-  1.5

0.3- 28.3

0.7-  6.8

0.6-  5.7
Chlorine. Hardness.*
O.I- 0.8 \  1.3-  6.8
  ----     2.5-  4.9
0.9- 2.4 1  7-7- 13-9

0.5-12.8 :  4-7- 57-3
  ----    22.6- 45.4
0.8-25.2 '    ----
  ----    10.3-124.9
0.1- 1.3  199- 22.8
  ----     1.3- 13.3
0.1- 6.8 !  2.1-  3.5
  ----   I  1.3- 27-i
1.8- 4.6  19.2- 21.3

1.8- 2.3   7.9- 24.5
* The hardness is in German degrees. 
CHAPTER VIII.
       ARTIFICIAL  IMPROVEMENT  OF NATURAL WATER.

   NATURE sometimes furnishes water which leaves nothing to
be desired in respect  to quality, but, unfortunately,  the best
water—such as is sometimes derived from  springs and not un-
frequently from  the ground water—is apt  to  be  limited in
amount, and, very generally,  a supply sufficient in quantity can
be procured only from  a source possessing some undesirable
qualities.  Although a water which  is polluted to any consid-
erable extent by  sewage is not capable of purification by  any
process practicable on  the large scale, so that it  can  safely be
used for domestic supply, the character of many natural waters
may be sensibly  improved by proper treatment.  Again, there
are circumstances under which it becomes  absolutely necessary
to use a bad  water or none at all, and in such cases purification
must be accomplished  if possible.
   We  shall consider   various methods of  improving  potable
water under the following heads :
   I.   Sedimentation and storage.
   2.   Filtration  (on the large and on the household scale).
   3.   Clark's process for softening hard water.
   4.   Other (chemical) processes.
   5.   Distillation.

                  Sedimentation and Storage.
   When a stream or other body of  surface water is  used as a
source of  supply, the best  way—speaking solely from a sanitary
point of view—is to pump directly from the source into the dis-
tribution  without the  intervention of settling basins and reser-
voirs.    This is  not, however, generally practicable.   In some
cases  the general or  occasional turbid character of a  stream
renders sedimentation necessary,  and in  other cases storage
basins  are necessary in  order that the stream may furnish a suf-
ficient quantity of water during the dry season. 
SEDIMENTATION.
147
    Sedimentation.—The  particles of  suspended matter which
 render a stream turbid or muddy, regularly or in times of flood,
 are of a greater specific  gravity than the water itself, and settle
 out more or less completely if the  water be allowed to stand
 quiet  for a time.  Lakes and  ponds are natural settling basins,
 and have this  advantage over running streams, that they  are
 much less liable to be rendered turbid by freshets ; they are not
 however, usually entirely free from  floating particles, but  the
 suspended matter in this case cannot be removed except  by
 filtration.
    Some figures have been already given in  Table VII to show
 the various amounts of suspended matter in certain rivers.   It
 is well known that the water of many of the rivers in this coun-
 try, especially  in  the  West,  is  not,  in its natural condition,
 acceptable,  if indeed it  can be regarded as at  all  suitable  for
 use.  It is said* that the sediment in the  Mississippi (or rather
 the Missouri) at St.  Louis amounts at times to 1.8  per cent  of
 the bulk of the water.  About 94.5 per  cent of  the  sediment is
 deposited within 24 hours in still water at ordinary stages of the
 river, but for two months in the year, during floods, there is so
 much fine sediment that  no amount  of settling will clarify the
 water.
    It  is desirable to remove the  suspended  matter, not simply
 on aesthetic grounds,  because it renders the  water less acceptable
 to the eye, but also because particles of gritty mineral matter, or
 even of clay, often cause diarrhoea, especially in the  case of per-
 sons not in the  habit of  using  the water, to which many persons
 do become accustomed by use.  Where thorough filtration is  for
 any reason impracticable, sedimentation serves a useful purpose.
    There are now at St. Louis  four settling basins, 600 x 278 feet,
 and 19 feet deep.   The floors  are paved with brick on edge and
 slope toward the center and the river side.   The basins are used
 alternately, one  being drawn from, one filling and two settling,
 or one settling and one being cleaned.   The sediment is removed
 from  each basin about  once  in  four months, some 16 inches
 being collected in that time.  The sediment is floated off with a
 stream of water, at a  cost of from 0.84 cent (1879) to 1.05 (1878)
per cubic yard.
Engineering News, 1881, p. 142. 
148
WATER SUPPLY.
   As an accompaniment of a scheme of filtration, settling basins
are in many  cases essential.   Where a  stream  is  subject  to
sudden and transient periods of turbidity, besides serving in their
proper capacity, they may also serve as storage basins and  make
it  possible to  avoid  altogether taking water  from  the stream
when it is at its worst.
   In following the variations of a turbid water, or in tracing the
progress of sedimentation, estimation of the amount of turbidity
is usually made by simply looking through a certain depth of the
water  in a tube or other glass vessel.  Several attempts have
been  made to reach more  accurate results, and Grahn and Sal-
bach* have proposed  to apply the  principles of photometry to
the solution of the problem.
Fig. 27.—salbach's photometer, elevation,  (from fischer.)
Fig. 28.—salbach's photometer, plan,  (from fischer.)
   Figures  27 and  28 represent Salbach's arrangement of the
photometer.  P carries a disk of paper on which a spot has been
made transparent  by means of  oil or stearine; at the beginning
P is set at the zero point of the scale, and the burners, B B, reg-
ulated so as to give an equal amount of light.   C is a leaden box
the glass sides of  which are exactly parallel, and 100 millimeters
apart.  When C is filled with turbid water a portion of the light
* Journal fUr Gasbeleuchtung und Wasserversorgung, xx (1877), p. 545. 
STORAGE.
149
given by the right-hand burner is  cut off, and the screen P must
be  moved  nearer  to this  weakened  source of light  in order
that the  illumination on both sides may be equal.  From  the
distance through which  the screen must be moved, it is possible
to calculate the loss of light, and thus to obtain  an expression
for the amount of turbidity of the water.
    Storage.—Some of the disadvantages to which stored water is
subject in ponds and impounding reservoirs have already been
indicated—such, for instance, as undesirable increase of temper-
ature,  growth of noxious algae, etc.  On  the  other  hand, there
are certain  advantages in storing surface waters  in clean deep
basins exposed to the sun and air.  When strongly  colored sur-
face waters are thus stored, the dissolved organic  matter  under-
goes chemical change, and  a portion of it, being removed from
solution, settles out as a sediment; at  the same time  the color
becomes less marked.
    In  order to compare and estimate the depth of color  of vari-
ous waters,  or  of  the same water at  various  times, an  instru-
ment was invented and  used by a  medical commission which
investigated a number of sources of water supply proposed  for
the city of Boston.*   "The instrument consists of two tubes, -B
and D (Fig. 29), sliding water-tight one within the other, the
lower end of each tube being
closed  with  a disk of  plate
•glass.   Into the large tube, B,
just above the plate glass disk,
is  inserted  a small piece  of
tubing which terminates in a
funnel - shaped  receiver,  A.
Water poured  into  this  re-
ceiver will therefore pass into
the space between the two
glass disks, entirely filling the
outer  tube  when  the  inner
tube is withdrawn, and again
returning to the receiver when the inner tube is pushed down so
that the glass disks come in contact with each  other.  Through

    * Report of the Medical Commission upon the Sanitary Qualities of  the Sudbury,
Mystic,  Shawshine and Charles River Waters.  City  Document, No. 102.  Boston,
1874.
 
150
WATER  SUPPLY.
 an opening near the upper end of the smaller tube, D, is inserted
 one end of a rhombic prism, E, in which total internal reflection
 takes place twice.
    " This prism extends half way  across the inner tube, D, so
 that an  eye, looking through  the eye-piece, G, sees the field of
 vision nearly half filled by the surface  of the prism.  This ap-
 pearance is represented at /.  The eye-piece, G, contains a single
 lens, which is focused  upon the upper surface of the prism.  The
 position and angles of the prism are such that a ray of light out-
 side of, and parallel to, the tube B, is reflected, first  directly into
 the tube D, and then parallel to its axis, thus emerging from the
 prism and entering the eye-piece alongside of the rays of light
 which have passed through the two  plate glass  disks.  It will
 thus be seen that the conditions for comparing the color and
 intensity of these two sources of light  are as favorable  as pos-
 sible.  A piece of white card, C, fastened at the lower end of the
 larger tube,  throws  a uniform white light  through the tubes
 B and D, and also along  the  outside of the tube  B, into  the
 prism E.
    " In using this instrument, a piece of brownish-yellow glass, F,
 is placed in front of  the prism E, and the water, whose color is
 to be determined, is poured into the receiver A.  The inner tube
 is then withdrawn until the column of water between the two
 glass disks is sufficiently long to give to the light passing through
 it a  color equal to that imparted by the colored glass F to the-
 light passing through  the prism E.  The length of this column
 of water, which will, of course, vary  inversely  with the depth of
 color, can  be  determined by  means of  the scale on the  inner
 tube D.  By this means, the relative  intensity of color of various
 specimens  of  water  may be determined with considerable  ac-
 curacy."
   Aeration.—Although a water colored by vegetable matter
 loses color when exposed to sunlight in closed vessels, it is prob-
 able that the changes which take place in storage basins are due
partly to the action of the air.  There is no doubt that the pas-
sage of the water over natural falls or artificial dams tends to its
improvement,  or that the stagnation  of water in " dead ends,1' or
in small reservoirs without circulation,  tends to its deterioration.
In the larger reservoirs and ponds the winds play an important
part in agitating and aerating the water, but  it is very doubtful 
FILTRATION.
151
if  any scheme for  artificially aerating  the water would  accom-
plish enough to pay for the outlay involved.

                          Filtration.

   The filtration of water on the large scale has been practised
in England and on  the continent of  Europe for many years, and
has become very  general in cases where the supply is taken from
streams or ponds.   From statistics which were laid before the
Diisseldorf meeting of the German  Public  Health Association
(in 1876) by Engineer Grahn,* it would seem that in Germany,
since 1858, there  has been no  town of considerable size supplied
with unfiltered river water, while the increase with reference to
other sources of supply may be seen from the following data:

 TOTAL NUMBER OF INHABITANTS IN 80 TOWNS OF GERMANY, GERMAN-AUSTRIA,
                        AND SWITZERLAND
Supplied with	1858.	1876.
	460,000 1,060,000 25,000 45,000	460,000 1,697,000 1,519,000 1,719,000
		
		
		
		
    In the United States very little has yet been done in the way
of systematic filtration on the large scale, although, in  some lo-
calities, attempts  have been made to improve  the  condition of
the water by intercepting some of the suspended matter.
    Filter beds,  as usually  constructed,  are  water-tight  basins
some ten feet or more in depth, the sides built of masonry, and
the bottom puddled  or made  of  concrete, or paved with brick
and cemented.  The  area  may be from  20,000 to  50,000, or in
some cases even 150,000 square feet.   In building  up the filter-
ing bed, provision  is first made for the  ready  collection  of the
water by constructing upon  the  floor of the basin drains  or
channel-ways of stone or brick laid dry;  then follows a layer of
broken stone, the fragments being three or four inches in diame-
ter.  This is succeeded by gravel screened so as to be of uniform
size, a layer of  coarse  being followed  by one or  more layers of
finer  material;  upon the gravel rests  sand,  likewise separated
   * See the Deutsche Vierteljahrsschr. fur offentl. Gesundheitspflege, ix (1877), p.
108. 
152
WATER  SUPPLY.
 into layers of uniform size.  The exact thickness of the different
 layers, and the extent to which  the separation into the different
 sizes is carried, are subject, of course, to considerable variation.
    The water stands several  feet deep  over the surface of the
 sand, and is allowed to flow down through the filter at such rate
 as experience shows to be most advantageous.   Naturally, when
 the sand is clean, a greater quantity of water can be  passed in a
 given  time  than when  the sand has become clogged; practice
 differs as to the  maximum rate, but it is seldom over six inches,
 vertically, per hour, and often  less.  At the rate mentioned, each
 square foot of surface would deliver 12 cubic feet (or 89^ United
 States gallons) per day.
    When the beds become clogged  so as no longer to filter with
 sufficient rapidity, the water is drawn out from the beds, and the
 upper layer of sand, for a depth of  one-half or three-quarters of
 an inch, is removed.  When by successive parings the thickness
 of the sand has been considerably reduced, that which has been
 removed  is washed  and replaced so as to restore the original
 thickness, the waste of  washing being made up with fresh  sand.

                Principles of  Sand  Filtration.
    Having thus stated briefly the main features of ordinary
 sand filtration, we will proceed to discuss the principles which
 govern filtration  in  general,  and afterward  consider certain
 special points with  reference  to  the successful carrying out of
 the process.   For this purpose we  shall  consider the " impuri-
 ties " of ordinary water as divided into three classes: first, the      j
 suspended  matters, whether   of  mineral, animal  or  vegetable
 origin;  second, the dissolved mineral or  saline matters ;  third,
 the dissolved organic matters.
   The action which takes place when an  ordinary water  is
 passed through a sand filter is  threefold.  In the first  place, the
 most  obvious action is the arresting of suspended particles of
 solid matter  which are  too large  to  pass  through the pores of
 the filter.   The second action partakes something of the charac-
 ter of  sedimentation, and may  be well illustrated by the follow-
 ing experiment:
   Take two jars of  equal size, and  fill one of them with  frag-
 ments of broken rock as large  as  half a fist, or with very coarse
gravel, arranging the material so that  a syphon can be inserted 
PRINCIPLES OF  FILTRATION.
153
as shown in the figure
by  stirring  up
some fine clay in
water and allow-
ing  the coarser
particles to sub-
side.  With this
turbid water  fill
both jars and al-
low   them  to
stand for twelve
or fifteen hours.
Then, by means
of syphons reach-
ing to the same
depth  in   the
Prepare now a quantity of a turbid liquid
Fig. 30.
 jars, carefully remove a quantity of water from each.  It will be
 found that the water from the jar containing the broken stone is
 perceptibly clearer than the other.
    The same thing may be shown  by allowing a turbid water to
 flow very slowly through a  trough filled with broken stone.  In
 these cases the interstices between the fragments are so many set-
 tling chambers, as it were, and the  particles of the clay deposit
 not only upon the floor of these chambers, but also on the sides
 and roof, being drawn  thereto by a sort of  attraction.   In the
 case of a sand filter, the interstices are small and very numerous.
    The third  sort  of action  which  takes  place in the  porous
 material of a filter is the removal of substances which are actually
 dissolved in the water.   As far as the mineral or saline matters
 are concerned, this action is trifling, although  not inappreciable
 with certain filtering media: with sand filters we can say that
 there is, practically, no  effect  on the dissolved mineral matter,
 unless there is opportunity  for a chemical  change to take place.
 Thus, it seems to be well attested, that  a hard water containing
 bicarbonate of lime may deposit carbonate of lime in the filter,
 owing to the escape of  carbonic acid.*   Sometimes the amount
   * See, for example, Lefort, Chimie  Hydrologique, pp.  165,  200.  It  has also
been shown by Schloesing (see Assainissement de la  Seine, 2ieme partie, Enquete, p.
 191), that at some depth in soil which had been irrigated with sewage, there were
formed crystals of carbonate of lime,  owing to the escape of carbonic acid  from the
sewage water, which contained a small proportion of  bicarbonate of lime in solution. 
154
WATER  SUPPLY.
 of mineral matter may be greater in the filtered than in the un-
 filtered water, if the material of the bed, the gravel and stones,
 contain, as they often do, soluble ingredients.
    With reference to the  dissolved organic substances, it may
 be said that a small but  appreciable amount may be removed by
 a well-conducted sand filtration ; the action may be explained in
 two ways.   In the first place, most porous substances  possess
 the power of removing certain kinds of organic matter by some-
 thing which may be called adhesion.  The absorptive power for
 any substance is  limited and soon reached, and the substance
 thus removed may by appropriate  means be again brought into
 solution.   Quartz sand, as we should infer, possesses the power
 to a slight degree only.  In the  second place, dissolved organic
 matter is removed in the sand  filter by oxidation.  The sub-
 stance is actually burned more or less completely, in part by the
 oxygen held in  solution in the water, and in part by the air en-
 tangled in  the  interstices of  the sand.  Although in filling the
 beds with water, great care is taken to displace the air gradually,
 and as completely as possible, there must always some remain in
 the concavities  of the individual grains of  sand  and otherwise
 entangled.   The extent  of the action  of  a sand filter  in this
 direction  depends  not only  on the fineness  of  the filtering
 medium, and the rate at which the filtration takes place, but also
 and in considerable measure upon the frequency with which the
 filter is cleansed.  The cleansing of the filter not only removes
 the accumulation of organic matter, which, if allowed to remain,
 would tend to injure the water, but also involves the aeration of
 the sand, at least to a considerable depth.


                     Details  of Practice.

   We now proceed to some more particular details of the prac-
tice of sand filtration.  The quality of the sand  employed is by
no  means a matter of  indifference, and  in  the case of  waters
which usually or occasionally carry finely divided clay in suspen-
sion, a great deal depends upon having  proper  sand and a slow
rate of filtration.  It may be said, in general, that the sand em-
ployed should be made up mainly of grains from X of  a milli-
meter to i millimeter in diameter, and the more  uniform the size 
DETAILS OF PRACTICE.
155
of the grains the better.*  A considerable proportion of larger
grains does no harm, but the  smaller particles should  be washed
out before the sand is  used ;  as a rule, sand that has been used
and washed is better than fresh sand.  As the fineness of the
sand increases, its efficiency as a filter increases, but the difficulty
and cost of filtration  increase  likewise, and more frequent cleans-
ing is necessary.  To  obtain the best and most economical results
with  a given water, special experiments  should be made with
reference to the sand best fitted for that water—although, to be
sure, it is not  always possible  to command that which would be
absolutely  the best.
   While it is, in general, true that the upper layer of sand does
most of the work  in  intercepting the various floating matters in
the water,  it does not do the whole under the conditions which
occur in  ordinary practice.  Examination shows that the sand  is
somewhat  affected to a greater depth, and it may occasionally be
necessary  to  renew  all the  sand.  The  very fact, which  will
appear presently, that in all  actual works there are  times when
the water  is imperfectly clarified,  shows  that  the  interior of a
sand filter  must in time become more or less foul.
   It may  perhaps be asked, why, if the work is practically done
by the first few inches  of  sand, it is  necessary to bestow such
care on the construction of  the beds, and on the arrangement of
the materials employed.
   In  the  first place, it is a well-recognized fact, that the worst
possible filter  is one  in which the portions of material of  different
sizes are  indiscriminately mixed. " The different degrees of fine-
ness  in the materials beneath the sand, and their several thick-
nesses, were intended first to prevent the fine sand from following
the water  downward into  the drains, and next to  insure the
presence of such a body of clean water below the surface of the
filter as would penetrate the numerous joints and openings of the
drains, and keep them  full, without creating anywhere currents
or veins of water of any perceptible difference of velocity.
   " With  the drains much nearer to the body of the sand, it
will be understood that  the tendency of the water would be to
flow  through  the filtering material more rapidly just  over the
   * Mr. Charles Greaves, of the East London Works, says '' sand that would go
through a screen consisting of 32 or 33  No. 10 wires in 6 inches," is the best, accord-
ing to English experience. 
i56
WATER  SUPPLY.
 pipe than at five feet on either side of it.  The distance through
 which it had to travel might be so short as to induce its concen-
 tration.  The low velocity at which the water flows through the
 filter, the uniformity of fineness in the sand, and the distance of
 the collecting  drains from its  surface, all work together to  pro-
 duce  that regularity of action over the entire filter bed upon
 which its perfection depends." *
   The rate of filtration must be determined by the character of
 the water and the condition of the filters.  The maximum  rate
 given  on page 152 as 89%; U. S. gallons per square foot  in 24
 hours would be equivalent to about 3^  cubic meters per square
 meter of surface.  The practice of most works falls considerably
 below this as an average rate ;  thus at Altona, where, to be sure,
 the constantly turbid water of the  Elbe is filtered, the average
 rate is only  1.5 cubic meters per square meter of  surface in 24
 hours.  It is stated that  the sand  here employed is coarser than
 necessary, and that with  somewhat finer sand  a more rapid rate
 of filtration  would be possible, f
   There is  considerable difference in practice as to the depth of
water kept  upon the  surface of  the  beds and the head  under
which  filtration takes  place.  Moreover, the head under  which
the water is  filtered varies at any works according to the condi-
                           tion of the sand.  The clear-water
                           well is generally so arranged that
                           the  height of water in  it can be
                           lowered at pleasure ;  and  the head
                           under which the water is filtered
                           is the difference  between  the level
                           in the bed and  in the clear-water
                           well, as may be seen, in the accom-
                           panying cut, where  the  head is
                           measured by the distance between
                           a and b.  While the beds are clean,
                           a difference of from 9  to  12 inches
                           suffices to  cause a proper rate of
                           flow;  as they become  clogged a
   ch greater pressure is  required, but it is not  desirable to  in-
   * Kirkwood, Filtration of River Waters, p. 10.
   t Samuelson, Nachschrift to German  edition of Kirkwood's Report.  Hamburg
 
DETAILS OF  PRACTICE.
157
 crease the pressure to too great an extent, as the sand is thereby
 fouled to a greater depth and compacted more than is desirable.
    The frequency with which it is necessary to cleanse the beds
 depends upon circumstances.  In the worst stages of the English
 rivers a filter bed has to be cleaned  once a week, rarely oftener.
 When the rivers  are  free from  turbidity, cleansing may  not  be
 necessary more than once a month, or in some cases once in two
 months.  The general method of cleaning has already been indi-
 cated.   In  some places  the practice is different.  At Zurich, in
 Switzerland,  it  is  the custom to clean  the beds by forcing the
 water in a reverse direction through the  filters.  Workmen, clad
 in rubber clothing, then stir  up the  upper  surface of the sand
 with forks, and the  collected  slime is  washed off and  floated
 away.  This  requires an abundance of water, and  the ability to
 command the requisite pressure.  One would suppose also that
 it would involve some  danger of disturbing  the arrangement of
 the filtering material.
    Certain recently published details of the manner in which the
 filtration works at Berlin* are conducted, are of considerable in-
 terest, as the  condition of things is similar to that which exists in
 some of the surface waters of  our Eastern States.  The water of
 the  Spree, besides being somewhat polluted by sewage and being
 in  a constant roily condition,  possesses, especially  in  time of
 flood, a deep brownish-yellow  color, and,  at times,  a peculiar
pondy taste due to vegetable extractive matter.   Moreover, from
 spring until  fall,  a more or less  copious growth of alga adds  to
 the  disagreeable character of the water, similar to those described
 and figured on page 86.
    The filter  beds are construced on the English model and are
 eleven in number—three covered and eight uncovered—having a
 total area of  37,000 square meters.  The filtration is  carried on
 at a very slow rate.  The  water is used, of  course,  in  varying
 quantities from hour to hour, and, on account  of  the small size
 of the clear-water reservoir,  a constant rate of filtration is impos-
 sible ;  the maximum  rate is, however, not over 0.1  meter down-
ward per hour.   For the greater part of the time 1 square meter

   * Mittheilungen liber natilrliche und  kiinstliche Sandfiltration.  Nach Betriebs-
resultaten der Berliner Wasserwerke vor dem Stralauer Thor, bearbeitet von C. Piefke,
Betriebs-Ingenieur.  8vo, pp.  75.  Berlin, 1881. A review  and  abstract of this
pamphlet appeared in the Journal of the Franklin Institute, December,  1881. 
i58
WATER  SUPPLY.
 of sand  surface is not required to furnish much more than one
 cubic meter  of water in twenty-four hours.  This would be at
 the rate of only 24^ U. S. gallons per square foot, and very much
 less  than is the practice  in many other  places.  The head under
 which filtration takes place is  seldom more than 0.5 meter (say
 20 inches), but even with this  low pressure and  slow delivery it
 has been found impossible, with  clean sand alone, to filter  the
 water satisfactorily.  If the unfiltered  water be allowed to stand
 a fortnight or so,  although the  larger of the suspended particles
 will have settled  to the  bottom, the water still retains a milky
 appearance, and sand alone cannot remove the exceedingly fine
 particles to which this appearance is due.   On this account  the
 water from a freshly cleaned  filter is not used at once, but is  al-
 lowed to stand on the bed and then to pass through very slowly
 until a thin coating has formed on the surface  of the sand. This
 coating is essential to the removal of the finest particles from  the
 water subsequently filtered.  Of course, as the coating becomes
 thicker the filtration becomes more difficult   until it  partially
 stops and the filter is " dead."
   As has been hinted  above, the great trouble in summer is
 from the  abundance of  small  algae which soon clog the filter.
 When the algae are absent, a  square meter  of  surface usually  fil-
 ters 20 cubic  meters before cleaning is necessary ; but in summer
 the capacity  is not over 10 cubic meters to the same area, and
 when a slimy coating of  decayed algae covers the surface of  the
 sand it  becomes  impossible,  under the pressure commonly em-
 ployed, to pass more than 2 cubic meters of water through 1 square
 meter of sand surface.   In the Berlin beds the thickness  of  the
 sand is 600 millimeters (about 2 feet). At each cleaning the sand
 is removed for a depth  of about 10 millimeters, but fresh sand
 is not returned to the bed until only about 200 millimeters of the
original thickness remain. The foul sand is allowed to stand ex-
posed to the  air until, by decay, the organic matter has  lost  its
 slimy character; it is then washed and eventually replaced upon
 the beds.  When  the filters are emptied the water is drawn com-
pletely off, and by successive and systematic stirring nearly the
 entire thickness of the sand is  exposed to the air, in order that
the small amount of organic matter which was not retained  at
the surface  may  be oxidized and destroyed.  With  the same
object in view, the air is allowed to circulate  freely, for  several 
PRACTICAL RESULTS OF FILTRATION.          159
days if possible, through the coarser underlying material.   These
filters are  filled  from below  with filtered water, and then the
water is passed  through slowly and is allowed to waste for sev-
eral days.

           Practical Results of  Artificial Filtration.
   As far as the suspended matter  is concerned, the  chief diffi-
culty in obtaining a bright and clear filtered water lies with the
finely divided clay which forms  the turbidity of many streams,
especially at times  of  high water.  The  Berlin  experience has
already been alluded to.   The  following table, taken from the
Sixth Report of the Rivers Pollution Commission (p. 215), will
give an idea of the efficiency of the filtration as practised by the
various London companies.  The observations being made on
monthly samples, the statements of the table will perhaps hardly
give a just idea of the  results obtained day by day; but they
will serve to indicate the fact that the mere possession of filter-
beds does not secure perfectly clear water at all times.

TABLE XXII.—Thames and Lea Water—Comparative Efficiency  of dif-
   ferent Rates of Filtration during the years 1868 to 1873, inclusive.
Name of Company.
         Thames.
Chelsea...............
Wrest Middlesex.......
Southwark and Vauxhall
Grand Junction........
Lambeth..............
           Lea.
New River............
East London..........
Maximum rate
 of Filtration
 expressed in
 inches per
   hour.
 7.27
 4.71
 6.O0
 6.97
12.00

 5.OO
 3-85
Number of Monthly Occasions when-
Clear.
Slightly
Turbid.
49
75
4?
55
42
70
5i
15
 0
24
14
n
Turbid.
 Very
Turbid.
 5
 o
 5
 7
12
 o
 3
 6
 0
 4
 0
10
 o
 2
   As already explained, in addition to clarification of the wa-
ter,  ordinary filtration  does remove  an appreciable amount  of
organic matter previously held in solution.   In addition to the
explanation given on page 153, it may be said that a part  of the
effect which has been observed  may be ascribed  to  the oxide of
iron,*  and perhaps  other minerals, which exist in the sand used
for filtration, the sand being seldom or never pure quartz.
   The effect of filtration on the water of the Thames and Lea
   * This is the view of  Thomas Spencer, the inventor of the so-called " carbide of
iron," used sometimes as a filtering medium. See page 166. 
i6o
WATER SUPPLY.
has been made the subject of  experiment  by the Rivers Pollu-
tion Commission and others.  The following table includes some
of the results obtained:
TABLE XXIII.—Observations on the Water of the various London
                         Companies.

                 [Results expressed in Parts per 100,000.]
Company.
            New River.
New River, Stoke Newington


New River, New River Head

          Thames River.

Southwark, Hampton.......


Chelsea....................


Lambeth..................


Grand Junction.............


Southwark, Battersea........


West Middlesex............

            River Lea.

East London...............
Date.
1873. Jan. 25..	
Jan.	27..
Jan.	31-
Jan.	3L-
Jan.	3L-
Feb.	3--
Feb	5--
Feb	7--
Feb. 1.
( Unf..
\ Filt'd.

(Unf..
\ Filt'd.


(Unf..
I Filt'd.

(Unf..
\ Filt'd.

(Unf..
(Filt'd.

(Unf..
(Filt'd.

( Unf..
\ Filt'd.

( Unf..
j Filt'd.
Unf..
Filt'd.
o§°o


< w o
QM" M
o
O
31. 9SO. 3500.084
30.160.2460.042
31.96
31-56
O.330
O.242
32.OO
31-56

31-36
31  10

32.96
32.74

31420
30.68 o
 321
.273
 325
.258

• 273
,258
.262
 231
31.800.
30.900.

31.220,
30.560.
0.061
0.043

0.063
0.042

0.046
0.032

0.067
0.038

0.042
0.032
2390.047
2260.035

209'o.o7i
i98]o.o43
34.68 0.3630.082
34700.3050.041
0.004
   0
0.004
   o
O.OOI
   O
0.003
   0
0.004
O.OOI
0.004
O.OOI
0.005
O.OOI
0.005
O.OOI
0.004
O.OOI
    From this table it appears that the filtration effects an appre-
ciable decrease in the amount of organic matter as judged from
the  " organic carbon"  and  " organic nitrogen."   In  ordinary
practice this effect is trifling, and sand filtration is not sufficient
to remove  the color which many surface waters possess, nor  to
completely remove the unpleasant taste which sometimes affects
such waters.   On these points the author has satisfied himself by
abundant  experiments,  and this is also the experience at Berlin.
Here, as has been mentioned, the Spree water often possesses to 
RESULTS  OF FILTRATION.
161
a marked degree  the brownish-yellow  color  common to  streams
which flow through marshy or peaty regions, and to the water of
most impounding reservoirs.  This  color, with the  taste which
at times accompanies it, gives rise to general complaint, but even
very slow filtration fails to remove it to any  considerable extent.
The slight action which  has been observed in this connection,
Piefke, resting on experiments made with prepared cellulose,
ascribes rather to the sediment containing vegetable fiber, than
to the  sand itself.  Table XXIV contains the results of a few
examinations  of  water from  certain American  localities:  here
the amount  of organic matter is indicated  by the " albuminoid
ammonia," and this, when the filter beds are in good working order,
is appreciably  less in the  filtered than in the unfiltered water.

TABLE  XXIV.—Examination of Water from Poughkeepsie and Hudson,
                              N. Y.
                   [Results expressed in Parts in 100,000.]
a > 3 U u X	
i-<	
1877	
Nov.	13,
Nov.	13,
Nov.	19,
Nov.	19-
Nov.	27,
Nov.	27.
Dec.	10,
Dec.	10,
1878	
Jan. i	8,
Jan. 1	8,
Locality.
  Poughkeepsie.
River............
Clear-water basin.

River............
Clear-water basin.
    Hudson.
River............
Filtered water... .

River............
Filtered water... .

Top of filter bed,
  i.e., unfiltered
Filtered water..
	<	Solid Residue.		K SB til u
< z 0 S s <	a 0 2. CO z, < 2			< X. U) X 0 h 3 z 0° -1 $ X
		" Organic and Volatile."	Total at 212° Fahr.	
0.0109	0.0197	1-7	12.1	10.1
0.0077	0.0139	I.I	9.1	9.0
0.0104	0.0157	1-5	10.5	8.6
O.OII2	0.0155	i-3	9.4	9.0
O.OO59	0.0152	1-13	8.21	
O.OO4O	0.0123			
O.OO5I	0.0152	0.72	8.40	
O.OO56	0.0131	1.02	8.14	
O.OI23	0.0133	1.12	IO.64	10.00
0.0237	0.0163	0.92	II.12	10.60
Remarks.
Very turbid.
Clear.

Very turbid.
Slightly turbid.

Turbid.
Slightly turbid.

Turbid.
Slightly turbid.

Turbid.

Slightly turbid.
              Sand Filtration in the  United States.
   Up to the present time there has been very little done in this
country  in the  way of  systematic filtration of water supplies,
partly, perhaps,  from indifference  and  lack of information, but 
162
WATER SUPPLY.
 mainly on account of the expense.  The numerous complaints
 which arise in the  case  of almost every city and town supplied
 with surface water render the question of filtration an important
 one, and  attempts have been made in various places  to  accom-
 plish the  desired object with a less expensive and elaborate plant
 than that required by the English system.
    Poughkeepsie, on  the  Hudson River, in the State of  New
 York,  was the first city in  the  Union to  adopt a scheme for
 the artificial filtration  of the entire water supply.  The filtering
 works consist * of a settling-basin 25 x 60 feet in plan and  12 feet
 deep,  in  three  compartments, arranged with reference  to  the
 deposition  of the heavier particles of mud before  the water
 passes on to the beds.  The  two filter beds are each 200  by 73^
 feet in plan, and  12 feet deep, built with vertical walls ; each has,
 therefore,  14,700  square feet  of filtering area.  The 6  feet of
 filtering materials, beginning at the top of the bed, are disposed
 as follows :
                  24 inches of sand.
                   6   "   " -jf inch gravel.
                   6   "   " £  "
                   6   "   "1  "
                   6   "   "2  " broken stone.
                  24   "   " 4 to 8 in.  "   "
             Total, 72 inches.

   The beds have a concrete bottom or floor 12 inches in thick-
 ness, upon which are arranged open stone culverts to  conduct the
 filtered water to the intermediate basin. The flow of water from
 each bed  to this intermediate basin is controlled by a gate, so
 that while one bed is being cleaned the other may be used.  The
 filtration  is conducted in the usual manner,  as is also the clean-
 ing and renewal of the sand, an inch or so of sand being removed
 at a time, and the sand being washed and  replaced only when
 the upper layer has been much reduced in thickness.
   The intermediate  filtered-water basin is 6x85 feet in plan,
and  16 feet  deep.  This  retains the  filtered  water until  it is
allowed to pass into the filtered-water reservoir.  This reservoir
is 28x88 feet in plan, and 17 feet deep, and from  it the water is
pumped to the uncovered  distributing reservoir from which  the

   * See Fourth Annual Report of the Water Commissioners of the City of Poueh-
keepsie for the year ending Dec. 31, 1872. 
COVERED FILTER BEDS.
I63
 service pipes are fed.   Sluice gates and drain pipes  permit the
 lowering of the water on the beds in any or all of the basins.
    The city of Hudson, N. Y., is also supplied from the Hudson
 River.  The  river water is pumped to the summit of a hiil over^
 looking the town, on which  are  situated the filter bed and the
 distributing reservoir.   The filter basin * is  13^ feet in depth, is
 built with sloping sides, and has an area, at the surface of the
 sand,  of 9,081  feet.
    The filtering material is  six  feet deep,  and is  arranged pre-
 cisely as in the Poughkeepsie works  which have  been already
 described.  The fragments of broken stone  rest upon a concrete
 floor six inches in  thickness,  having a slight inclination toward
 the middle or axial line, and this  line toward the outlet.  Along
 this line runs an openly-laid stone culvert 18x24 inches, which is
 connected by  a cast-iron  pipe  under the division  embankment
 with the clear-water well.   From the clear-water well the filtered
 water passes  over a gate or  weir, where it  is measured and its
 flow regulated, to the clear-water basin or distributing reservoir.
 Thence  it passes ordinarily into the effluent chamber through
 fine copper-wire screens to the  18-inch supply pipe ;  but the
 clear-water well can be connected directly with the  supply main,
 so that the city may be supplied  from the  bed without  passing
 the water through the basin or distributing reservoir.   The dis-
 tributing reservoir is 20 feet deep ; its capacity is 3,200,000 gal-
 lons.   Chemical examinations of  the water  from these localities
 have been given in Table XXIV.


              Advantages  of Covered Filter Beds.

   The exposure of  a comparatively thin layer of  water on the
 surface of the filter beds has at  least two disadvantages.  In the
 first place, in summer the water  becomes heated and is, conse-
 quently, in a condition  to  favor the growth  of the  lower orders
 of plant life; in the second place, in winter there is likely to be
 inconvenience from the freezing of the  water.  In the climate of
 England neither of these difficulties is  as serious  as in countries
which  are  either much  warmer or much colder, and  the filter
beds are  universally uncovered.   On  the Continent,  however,
* See Third Report of the Water Commissioners of the City of Hudson, 1875. 
164                   WATER SUPPLY.

the beds and the clear-water reservoirs are sometimes covered as
at Berlin, Magdeburg and other places.  With reference to the
first point—vegetable growth—some trouble is experienced even
in England, and  the beds  become clogged with a confervoid
growth, which forms, as it were, a sort of carpet on the surface
of the sand, and this, when  the  beds are cleaned, can be raked
off or rolled up in a coherent sheet.  This trouble might  be
lessened somewhat by the use of  covered beds, but where the
water to be  filtered contains an abundance of minute algae, as is
the case with the water of the Spree, at  Berlin, there is  no
perceptible  difference in the condition  of the  covered and un-
covered beds.
   With reference to the  second point alluded to above—the
freezing of the water in winter—the European  practice, in loca-
tions where  the ice freezes to  any thickness, may be learned by
the following quotation from  Kirkwood's account of the Berlin
works:  " The  long and severe winters  here made special care
and precaution necessary in  the use of filters during the months
of severe  frost.   The filter beds  cannot be laid bare in mid-
winter; for the frost would in that case  penetrate  the body of
the filter  and render it  useless.   All the filters are,  in conse-
quence, during the winter months, kept  constantly covered with
their  maximum  depth of water, four feet.  Luckily  the  river
water  during  the  winter months  is in  its best state as regards
freedom from turbidity, and also as regards freedom from vege-
table  discoloration or impurity.   The  filters,  therefore,  have
comparatively little to intercept, and the river water is flowed
continuously upon them,  and  passes  through  them without
very  sensibly  impairing  their efficiency.  To  make provision,
however, for an unusually long winter, or for an exceptional
condition  of the river then, which may  occasionally occur, it is
evident that a larger filtering surface is desirable  than  would be
necessary in a milder climate.
   "The  ice forms  upon the filter beds 15 inches thick,  and
sometimes, though rarely, 24  inches thick.  To protect the en-
closing walls of each filter from damage, the ice is kept  separated
from the walls, 6 to 12 inches, by  attendants appointed to that
duty; and, so long as the cake of ice is kept  floating in this way,
the masonry is safe from any danger by its thrust.  That  this
service has been well  performed, is demonstrated by the  condi- 
FILTRATION IN WINTER.
I65
tion of the walls, which  are in the best of order, and nowhere
out of line, or abraded, that I could perceive."
   Since  the  date  of Mr.  Kirkwood's  report,  covered filter
beds have been  built, and  it is stated that the uncovered beds
are not cleaned  during the winter, the burden  of  the work
being  thrown  upon the  covered  beds.   At Poughkeepsie and
at Hudson,  the  filtering area  is not  sufficient  to deliver  the
water throughout the winter without occasional cleaning.  The
ice has therefore  to be broken up  and thrown, or rather, dragged
out.
   There is no question but that  water once filtered  should be
distributed as soon as  possible to the consumers.   If it is neces-
sary that  the  water should be stored, it should be in covered
reservoirs of small size, which can be readily emptied and cleaned
in case of necessity.  Apparently, the  spores of certain algae are
not removed by filtration: at any  rate, it  has been found that if,
after  filtration, the perfectly clear Spree  water  is allowed  to
stand for  eight or ten days, algae are developed.  This fact is of
no practical consequence  in a case like that of  Berlin,  where the
clear-water reservoir is too small to hold a single day's consump-
tion, and  where, consequently,  the water  is delivered at once
into the service mains.

                  Expense of Sand Filtration.

   The most valuable accessible data of the expense of filtration,
as drawn from  actual experience, are found  in the reports of  the
Poughkeepsie Water Works.  From these data it seems that the
expense may be set at from $2.50 to $3.50 per million gallons,
not allowing for the interest on the plant or for the cost of pump-
ing.  The  original cost of the beds was 854,000, the interest  on
which would exceed the  cost of  maintenance.   In 1879, Mr. J.
P. Davis,  City  Engineer of  Boston, Mass., estimated the  cost of
constructing and operating  artificial filters for  the Mystic water
supply of  the  city—10,000,000 gallons daily.   He allowed for
seven beds, each with  an area  of 33,000 square  feet,  and esti-
mated that the cost of pumping and of operating the filters would
be about  $5  per million  gallons, and the interest  on  the neces-
sary  works, at five  per cent, would be nearly $6.00 per  million
gallons, making the total cost about $11.00. 
166
WATER  SUPPLY.
              Filtering Materials other than Sand.
    Many other substances have  been proposed  from time  to
 time as suitable to replace the sand wholly or in part, and  to
 accomplish more than sand can by chemical action on the impu-
 rities of the water filtered.  The so-called carbide of iron, of Mr.
 Thomas Spencer, is used in several towns of England with some
 success.  The carbide of  iron is prepared by roasting  a mixture
 of hematite iron ore  and sawdust, and is held to consist mainly
 of the  magnetic oxide of iron : it is, no  doubt, an  efficient puri-
 fying agent.   It is, however, expensive, and could hardly be pre-
 pared for less than $20 or $2$ per ton,  and for the best effect
 should  be preceded by a rough sand filtration.   At Wakefield,
 England, where, to be sure, the  water is extremely filthy, and
 the bed confessedly overworked, the Rivers Pollution Commis-
 sion found that " the water, owing in part to putrescent fermen-
 tation and subsidence, and in part to filtration, was chemically lesf
 contaminated  than might be expected, yet on both occasions it
 contained a  large proportion of nitrogenous organic matter.   It
 was of a greenish-yellow color, and on one occasion  very turbid."
   Various attempts  have been made to use iron  as  a filtering
 medium since Medlock, in 1857, patented the process for purify-
 ing water by allowing it to stand for some time in contact with a
 considerable quantity of metallic iron.  It  is claimed that " spongy
 iron " is now being used with success at Antwerp.*  This mate-
 rial, which was introduced as a medium  for household filters a
 few years ago by  Prof. Bischof, is prepared by  reducing hema-
 tite ore, and is in a peculiarly porous or spongy condition.  The
 filters at Antwerp are said to have been laid out  to treat over
 two million gallons per day, but it does not appear that anything
 like that amount is yet treated.  The works went into  operation
 in June, 1881, and after twelve months  Dr. Frankland was re-
 quested to examine and report on them.  The following is taken
 from his report:
   " The water, which was abstracted from the river Nethe, about
fifteen miles above Antwerp, is first impounded in two reservoirs,
where it is allowed  to subside for from 12 to 24 hours ; from these
reservoirs it  is pumped on to the  spongy iron filters, whence  it
 flows by gravitation upon sand filters.

 * Circular of " The Spongy Iron Water and Sewage Purifying Company," London. 
FILTRATION THROUGH  SPONGY IRON.          167
   " The spongy iron filters consist of two layers of bricks loosely
laid upon a bed of concrete.  On the bricks rests a layer 3 feet
in thickness,  formed of  5 m.m. gravel mixed  with  one-third of
its bulk of spongy iron.   Then comes a layer 3 inches thick of
fine gravel, and lastly a stratum of sand 2 feet deep, making in
all 5 feet 3 inches of filtering material.
   " The sand filters are similarly laid upon bricks and concrete.
They consist  of  a layer of  5 m.m. gravel 1 foot thick, covered
with 3 inches of fine gravel and topped with 2 feet 6  inches of
sand,  making altogether 3 feet 9 inches of filtering material.
   " The area of filtering surface of each filter amounts to 7,302
square  feet, and the rate of  filtration varies  from 300 to 500
gallons per minute, or from 60  to 100 (imp.) gallons per square
foot per 24 hours.
   " The result  of the analysis of  the three samples of water
show  that even after subsidence for nearly 24 hours, the water
of the Nethe is exceedingly impure, being still turbid and loaded
with an unusually large proportion of highly nitrogenized organic
matter.  The composition of the water  as it  passed  on  to the
spongy iron filters is stated to have been:

   Total solids (mostly dissolved)....................... 21 parts in 100,000.
   Organic Carbon.................................... 0.623
   Organic Nitrogen................................. 0.219
   Ammonia......................................... 0.028
   Chlorine (combined)................................ 1.8
   Hardness—temporary.............................. 4.60
       ''    permanent.............................. 6.90
       "     total..................................11.5°

The water in this condition was very unpalatable.
   " The aggregate  effect  produced by  one filtration  through
spongy iron was  as follows:
                                            Total percentage reduction.
         Total  solids........................................ 4*-3
         Organic carbon..................................... 60.9
         Organic nitrogen.................................... 74-9
         Ammonia........................................... —
         Total combined nitrogen.............................. 77-3
         Chlorine........................................... o.
         Temporary hardness................................. 13-°
         Permanent    "   ................................. 35-3
         Total        "................................27.O 
168
WATER  SUPPLY.
   " The nitrogenous character of the organic matter was dimin-
ished from the initial proportion, nitrogen to carbon =  I : 2.84,
down to 1 :4.4.  By boiling, the hardness of the doubly filtered
water is reduced to 4.4 parts per 100,000, or 30 on Clark's scale.
   " Lastly, from being muddy, unpalatable, colored and much
polluted, the water of the Nethe was rendered colorless, bright,
palatable and fit for dietetic and domestic purposes."
   Wood-charcoal is  often used  in filters  of small  size, mixed
with sand.   Practically, however, it adds nothing to the efficiency
of a properly  managed sand  filter.   One way in which charcoal
is used is illustrated by the works of Marshalltown, Iowa.  Here
a filter basin, 32 x 16 feet, was built of masonry; and a filter floor
of two-inch  plank was supported on joists laid crosswise.  The
floor was pierced with three-fourth inch holes, and covered with
wire gauze.  On this there is a layer of charcoal four inches thick,
and above this 14 inches of clean gravel and sand.  At Clinton,
Iowa, a number of boxes, 16 in fact, filled with charcoal, gravel,
and  sharp sand, rest upon the conduit.  The water  flows on to
the boxes, and through the material into the conduit. The boxes
can be  raised  one at  a time  for cleaning.   In case of  fire, how-
ever,  the water is  taken  into the  conduit without  filtration.
Sponge, which is much used in filtering water for manufacturing
operations, such as paper-making, has been used to a limited ex-
tent in connection with sand and gravel, even on the larger scale
of a town supply.  Alton, 111., pumps from the Mississippi River;
and the water  is filtered through sponge contained in a cast-iron
filter box of 54 cubic  feet  capacity : this  box  fits into  a tight
chamber in  the aqueduct  leading from  the river to the pump-
well, and can be raised  by machinery.   The box can be raised,
the sponges renewed,  and the box replaced, in three hours.  The
amount of water filtered is about 150,000 gallons a day.  When
the river is muddy the  sponges are cleaned every three or four
weeks: sometimes, when the river is clear, not oftener than once
in three months.  An  attempt was made at  one time to filter the
supply of the  village  of Malone, N.  Y., through  a filter  of soft
brick, but  it was not  found practicable to  filter with  sufficient
rapidity.
   Many other water  works, in this country, make some attempt
to " filter " their water by passing it through broken stone, gravel
or gravel and charcoal, or even through  sand and  gravel.   In 
HOUSEHOLD  FILTRATION.
169
  general, the most that can be said of these arrangements is that
  they act with greater  or less efficiency as strainers, removing
  some of the coarser  matters ;  the infrequency of  the cleansing
  showing that  the work done cannot be very great.  As  an illus-
  tration of this point, may be mentioned a locality where the filter
  beds were constructed as long ago as 1853.   They  are built with
  sloping sides  and measure 50x60 feet.   The filtering material,
  which consists of sand, gravel, and pebble stones,  has an entire
  thickness of 24 inches, and filtration is carried on  under a head
  of from 10 to  15  feet. The beds are not used in winter, but when
  in use the amount  of water filtered daily is  1,500,000  gallons.
  The beds are cleaned not oftener than once a year.  This is an
  extreme case, but inadequate area and infrequent  cleansing  are
  the common faults of many so-called filters.   Of course, occa-
  sionally, the character of the suspended matter which is to be re-
  moved is such that a very simple straining  process is all that is
  required: this is the case with some of our streams on which are
 a number of saw-mills, and where the comparatively coarse par-
 ticles of  sawdust  comprise the  main part of  the impurity.  In
 such  a  case,  as,  for instance, at Eangor, Me., simple  passage
 through a limited amount of sand is all sufficient.

                      Household Filtration.
    In localities where there is a  public water supply, it is, with-
 out doubt, the duty of the water board or  company to  deliver
 the water to consumers in a condition fit for domestic use.  If
 the source which  is, on  the whole, the most available  for the
 water supply  is such  that  filtration is absolutely necessary, the
 water should be filtered on the large scale by the authority con-
 trolling  the  works.   Practically,  however,  in  the case of most
 existing water  supplies, the water as delivered to the consumers
 may be appreciably improved by  filtration ;  household filtration
 is also often  necessary in country  residences and in the  smaller
 towns where there is no public supply, and where it is necessary
 to use rain water which has been stored in tanks or  cisterns.
    For filtration on the household scale, numerous  devices have
been made and patented, and the greatest variety of material
has been proposed : many sorts of porous stone, sand, powdered
glass, bricks, iron  in turnings and other  forms, vegetable and
animal charcoal, sponge,  wool,  flannel, cotton, straw,  sawdust, 
170
WATER  SUPPLY.
 excelsior and  wire-gauze—these  are some of  the substances
 which are used.  A  filter suitable for household use must be
 made of a material which  cannot communicate any injurious of
 offensive quality to the water which passes through it;  it must
 remove from the water all suspended particles, so  as to render
 the water bright and  clear; and it  must either be readily cleaned,
 or the filtering material must be such as to be readily renewed.
 In addition to these requirements,  it is of  great advantage if the
 filter is  able to remove a noticeable amount  of the dissolved
 organic matter which most waters contain.
   As to the  filtering material,  the author * is satisfied that
 there is  nothing,  on  the whole, better than well-burned animal
 charcoal (bone-coal).  This material,  as is well known, possesses
 great power in removing organic matter from solution, and is
 used in the arts to decolorize colored  solutions :  on many organic
 substances  it acts, not  simply by adhesion, but apparently by
 bringing  them into contact  with oxygen, and thus absolutely
 destroying them.   Its  power  does not last indefinitely, and a
 bone-coal filter, like a  filter  of any other material, requires cleans-
 ing and  renewal at  proper  intervals.   Other materials to  be
 mentioned render good service, and in certain sorts of filters,
 as,  for instance, those  made for attachment to ordinary cocks
 or faucets, the bone-coal possesses no essential advantage.
   We  will consider first  the  filters  of small  size, intended to
 be attached to the faucet,  where the water is  brought in pipes
 either from the service-mains  of  a general supply, or from a
 tank in  the building; second,  the portable filters  intended to
 occupy a more or less permanent position, and  to be filled with
water,  either by some ball-cock or other  similar arrangement,
 or by means of smaller supplies continually  renewed ; third,
the more permanent  and  fixed devices  which are inserted or
built  into underground and  other cisterns, or are introduced
 into  the  course of the  service-pipes so that all the water  used
in the  house passes through  them.
   Considering the volume of water which must flow through
an extremely limited amount  of  material, no  filter'capable of
being screwed on to an ordinary water-tap can act in any other
way  than as a strainer,  and all that  can  be required of  such a
filter is that it shall remove suspended particles and be readily
     * See Nichols : Filtration of Potable Water. New York, Van Nostrand. 
HOUSEHOLD FILTRATION.
171
cleansed or renewed  at  trifling expense.   The older forms  of
filters, which  could  be cleaned  only by  unscrewing from the
tap and reversing either the whole apparatus or  some inside
receptacle of the filtering medium,  were all open to objection,
and no one of  them  was to be recommended  as  superior  to
the primitive and unpatentable device of attaching to the faucet
a bag of cotton-________________
   We  come now to the larger forms of filters, to those which
are portable, but  which are  intended  to occupy a  permanent
position in the room, or in some cases to be placed in the tank
from which the supply is -drawn.   The  material which, next to
simple sand, has probably been used as long as anything for the
purpose, is stone.   Some varieties of sandstone are particularly
porous,  sufficiently so to allow of  the use of slabs of the stone
as filters ;  other  similar substances, such  as pumice  stone or
unglazed earthenware, have been employed ; the most common
9999557 
172
WATER SUPPLY.
arrangement being to  insert the stone as a horizontal partition
in a small tank or vessel: the action is, in the main, mechanical,
and the sediment which collects upon the upper surface of the
block is removed by washing and brushing.  A material which
is used to a considerable extent  in England is  the so-called sili-
cated carbon : it is the residue of the distillation of  a certain
variety of bituminous shale.  Thus it is a coke mixed with min-
eral matter, and is compressed into blocks for use.  In the com-
mon form of household filters of this make, the block is cemented
as a partition into an earthen jar, and is not readily cleaned, but
there is no doubt that, until the filter  becomes  clogged, it  is
very efficient in  purifying water even from the dissolved organic
water, being separated as they               FlG- 34'
* A very similar filter made in Boston, England, is on salein this 
HOUSEHOLD  FILTRATION.
173
always  are, mainly at  the surface of the filtering material, may
fall away from it and deposit elsewhere ; the consequence of this
is, that  the filtering material requires less frequent cleansing.
    Bone coal  is also  used compressed into  cylindrical blocks
with an aperture in the center into
which the  delivery pipe is inserted,
and one or more of these  may be
placed in the tank from which the
water is taken.  As a  rule, the pre-
viously described method of using
the bone coal is to  be  preferred.
    Another material which has late-
ly come into use to a considerable
extent in England, is what is known
as " spongy iron," which has already
been  alluded to  in the description
of the filtration works at Antwerp.
The portable filters are constructed
in various  forms, but  on the  same
general  plan.  Fig. 35  represents
one form,  where the  water is  sup-
plied from  an inverted  bottle, which
must  be refilled as  often as empty.
In  other forms the reservoir of un-
filtered water is kept  full by being
connected  with the service pipe by
means of  a  ball-cock attachment.
The vessels are of earthenware, but
the spongy iron is also furnished  in
filters which can be inserted in tanks
or cisterns.
    Although, at  any  rate with the
smaller  forms of  filter, it is difficult
or impossible to obtain a water free  from iron, there is no doubt
that a considerable portion of the  dissolved  organic matter is
removed, and it is claimed that bacteria and bacterial germs are
completely removed.   These claims  are borne out by the experi-
mental investigations of Bischof* Hatton,f and others, and give
^//////////////////////////W/^//////^/.
Fig. 35.
* Proc. Roy. Soc, xxvii, p. 258.
\ Journ. Chem. Soc., xxxix, p. 247. 
174
WATER SUPPLY.
 to the material a great theoretical advantage.   Practically, how-
 ever, it is extremely doubtful whether in the ordinary use of the
 spongy iron in filters such results can be obtained ;  and at the
 best, the water must pass very slowly through the filter in order
 that purification may take place.   Like other materials used for
 the  purpose, it  affords a means for  improving an  undesirable
 water, and for  lessening  the  risk in using a doubtful water:  it
 does not  afford an excuse for employing a water known to  be
 impure, on the ground that possible danger will thus be certainly
 averted.
   Wood-charcoal is  sometimes used in household  filters, but,
 practically, it has next to no  chemical action.  The  author had
 occasion some time since to examine an American filter which  is
 much used in certain sections of the country, and in which the
 filtering medium  is wood-charcoal with  clean quartz pebbles.
 The filtering material is arranged in an oak tub and the water  is
 placed in a zinc pan at the top, and passes first through a hand-
 ful of sponge and then downward through the pebbles and char-
 coal.   The experiments extended over  several  months, and the
 water was examined by Frankland's and  by Wanklyn's method.
 In the case of the Boston water, when the filter was  in constant
 use,  absolutely no  effect was produced on the water—the water
 which issued from  the filter containing exactly the same amount
 of organic matter as when it entered.  If the sponge  were taken
 out,  thoroughly washed and replaced, there was for a short time
 a slight difference between the filtered and unfiltered water, but
 the effect was temporary and  soon ceased.  In spite of the bulk
 and weight of this  filter (the smallest size of which weighs about
 150 lbs.), the entire work with water of  this character seems to
 be done by the  handful of sponge at the top.  The filter is one
 of a class which  claim to be chemical  in  their action, but which
 cannot do more than remove  suspended matter ;  and the action
 on clayey  waters, with which the filter is  sometimes used to ad-
vantage, is probably largely due  to  the  principle  illustrated on
page 153 (Fig. 30).
   The following simple form of filter is described by. Dr. Smart,
and answers fully as well as many patented contrivances.  " The
filter is  made of  tin and consists of a modified funnel, the body
of which rests on a tin bucket  or receiver, while the tube projects
downward to the bottom of the said bucket.  The lower end of 
HOUSEHOLD  FILTRATION.
175
 the tube is tied over with some filtering cloth.  Three-fourths of
 its length  is filled with granulated bone charcoal and the upper
 fourth with sand. The upper end of the tube projects about half
 an inch  into the body of  the funnel to permit of tying a filtering
 cloth over the top of  the sand.  The angle between this projec-
 tion and the sloping sides of the funnel will serve to trap solid
 matter.  To clean this filter, the filtering cloth guarding the top
 of the tube will  have to be removed, washed, and  replaced. At
 longer intervals, when the filter shows signs of  clogging, half an
 inch of the upper layer of sand may be removed and replaced by
 fresh material.  At yet longer periods, depending upon the length
 of time during which the charcoal retains its powers of oxidation,
 the whole  contents of the  tube may  be dumped out and re-
 newed.  Earthenware is  more durable  than tin, and would pre-
 serve the water cooler during the warm months."
    There are various filters in the market which are arranged for
 use where there is a public water supply, by being connected with
 the service pipes in such a way that all the water entering the
 building passes through  the filter.  By proper  arrangement of
 valves it is possible to reverse the current and  cleanse the filter
 from  the collected impurities.    In some cases the valves  are so
 arranged that  the filter can be cleaned by a reverse current of
 hot water  or steam.   The revolving filters, mentioned on  page
 171 as adapted  to  faucets, are also made on the larger scale for
 insertion in the service-pipes of houses and other buildings and
 for manufacturers' use.
    We come now to the discussion of filters suitable for cisterns
 of considerable size, and  especially for  the underground cisterns
 in which rain water is usually  stored.   The collection of  water
 from  the roofs of houses involves the collection  of dust and dirt
 more  or  less  objectionable in character, especially in places where
 soft coal is burned.  Although it is possible  by automatic con-
 trivances to avoid the  collection of the first portions of the water
 coming at any time from  the roof,  yet these do not perfectly ac-
 complish their intended object, and are  not at all commonly em-
ployed.  Moreover, the construction of ordinary cisterns is such
that, after the water is once collected, it is liable to deterioration
and to contamination by  various foreign matters which fall into
it, so that,  if not absolutely necessary, filtration  is certainly very
desirable.  Where the  water  is  stored in tanks in the roof of the 
176
WATER  SUPPLY.
 building, one of the various forms of filters just  alluded to may
 be placed beneath the tank and so connected that all the water
 used shall pass through it.  The outlet pipe from the tank should
 start several inches from  the bottom, in order that the sediment
 may deposit itself as far as possible on the floor of the tank and
 not be drawn  into  the  filter: the tank should,  of  course,  be
 cleaned from time to time.  The disadvantage of  .this method is
 the inability to command a sufficient head of water to properly
 clean the filter by  reversing the current.  The  tank may  be
 divided by a partition and the water be required to pass through
 a filter constructed in  the tank itself and filled with sand and
 charcoal or bone-coal, or one of the patent tank  filters already
 described may  be employed. (See Figs. 33 and 34.)
    With  underground cisterns, it is not uncommon to construct
                               them so that  the water is not
                               pumped directly from the  cis-
                               tern, but  from  a sort of pump-
                               well, to enter  which  the water
                               must pass  through  a porous
                               partition  wall  made  of bricks.
                               These walls are constructed in
                               various ways:  one form is rep-
                               resented in the accompanying
                               cut,  taken from  " Scribner's
                               Monthly  Magazine"  for Sep.
                               tember, 1877.
                                  When the brick partition is
new, it  is undoubtedly of  good service;  but it soon  becomes
clogged, and  covered on  the outside with  a deposit  of organic
matter, so that  after a time the water which passes through the
brick wall must first have an opportunity to leach out what it
can from this mass of decaying matter.*  As a rule, the interiors
of cisterns are not  very accessible, and when the cistern is relied
upon as the sole or as a principal  supply for the household, it is
impossible to renew  frequently  the  filtering wall, or  even  to
thoroughly clean the outer surface.  The best that can be  done
under ordinary  circumstances is to clean the outer surface of the
wall as thoroughly as may be with a stiff brush every few months
* Some analyses of cistern waters thus filtered have been given in Table V 
HOUSEHOLD FILTRATION.
177
and to renew the wall completely whenever the probability of a
rainy season allows.  If the body of the cistern be divided by a
partition wall  into two compartments which  may be  made to
communicate or not at will, the two may be cleaned at different
times and thus the danger of a water-famine be averted.
   Other methods  for  accomplishing filtration  in the cistern
Fig. 37 (from Fischer).                         Fig. 38.
have been suggested for attachment to the suction pipe of the
pump, two of which are shown in Figs. 37 and 38.  Fig. 37 is a
German device for using bone-coal compressed into blocks : Fig.
38 is an American device for taking the water as free from the
sediment as possible.   The cylinder contains silicious sand for
the filtering medium and is buoyed up by an air-tight chamber
at one end.  The pipe has a swivel-joint  which allows the filter
          12 
178
WATER SUPPLY.
to accommodate itself to the level of the water in the cistern 01
reservoir.'"'
    Still another method of accomplishing the desired object con-
sists in placing the filtering material in a frame capable of sliding
in a groove and of being readily lifted  from its place.  The fil-
tering material may consist of porous tiles or of blocks of animal
charcoal;  and, if duplicate frames are provided, the grooves may
be so arranged that a fresh frame  can be lowered into place be-
fore the old one is taken away.  Figure 39f represents a cistern
constructed with such frames  containing blocks of animal char-
coal, as prepared  by Atkins & Co., London.  These  blocks can
be readily cleaned by scraping the outer surface (at some expense,
to be  sure, of the  material  of  the blocks),  and  they can  be
renewed when necessary.   They are  made  of various densities;
the most  dense  permitting the passage of 30 to 40 gallons per
square foot per day, while the most porous pass some 250 to 300
                            Fig. 39.

gallons.  For use in ordinary cisterns tolerably porous blocks
would probably answer well enough, and for such use as this the
* Scientific American, Jan. 10, 1880.
f This cut is taken from Fanning's Water-supply Engineering. 
          FILTRATION FOR MANUFACTURING PURPOSES.     179

 charcoal  is more conveniently employed  in this  form of  blocks
 than as fragments.
    The arrangement which has been  described is rather expen-
 sive for common use; although, if the necessary  provision were
 made in the original plan for the construction of the  cistern, it
 would, on the whole, be more satisfactory than other plans which
 involve less outlay at the start.  The author is not aware that
 the blocks of  compressed  animal  charcoal are prepared in  this
 country, but there would probably be no difficulty in obtaining
 them if there were any demand.
    There is one point worth noting in connection with domestic
 filtration, namely, that  in  this country we  are in the habit of
 putting ice  directly  into the pitchers or small tanks from  which
 drinking water is served.  Natural ice is  not always clean, and
 frequently,  after the  ice is melted, the water, even if clear at
 the start, will be found full of suspended particles, or having an
 abundant sediment.   Filters  are made so that  the ice cools the
 water before the filtration takes place and the difficulty can also
 be obviated to a  large extent  by inclosing the ice in a clean flan-
 nel or cotton-flannel bag.

            Filtration for Manufacturing Purposes.
    For the majority  of  manufacturing purposes  the  object of
 filtration  is accomplished  if a thorough removal of  suspended
 matter is effected.  Sand, wood-charcoal, bone-coal,  flannel and
 various other substances are employed as filtering media; very
 good results are obtained by the use of sponge, and  this mate-
 rial is employed to a considerable extent;  in some cases,  the
 water  is  filtered through  sand filters, similar to  those used in
 connection with town  supplies but on a smaller scale.
    Two filters  have recently been offered in the market to effect
 rapid  filtration for manufacturing purposes  and  also  for town
 supply.  The " Multifold Filter," manufactured by the Newark
 Filter  Company, may be  of  various sizes, and each apparatus
 consists of a number of  shallow cast-iron pans ranged one above
 the other.  Each pan has  a false  perforated bottom, on  which
 rests  a layer  of  sand, 6 inches or less in thickness,  and each
 works  as an independent filter.  The water passes in the di-
rection of the  arrows shown  in the cut under a  greater or less
pressure.  The chief peculiarity of the filter consists in the ar- 
i8o
WATER SUPPLY.
rangements for  cleansing.  When the  sand becomes  clogged,
                                          water is introduced
                                          under  pressure
                                          through  the hollow
                                          axis of the  cylinder,
                                          and  issues  in  fine
                                          jets from the radial
                                        ■*- arms, stirring up the
                                          sand  and  washing
                                          away the lighter sub-
                                          stances.  The  arms
                                          can be revolved from
                                          the  outside, so  that
                                          the sand may be com-
                                          pletely washed.
                                            Another  filter
                                          (system Piefke)  has
                                          been recently adver-
Fig. 40.
tised  in Germany,* where the filtering medium consists of cellu
lose (vegetable fiber) which has been impregnated with some anti-
septic substance.  This material is disposed on  a number of cir-
cular  sieves arranged one above another in an  apparatus some-
what  similar to the preceding, and a thin  layer suffices.  The
filter  is cleaned by revolving the vertical  axis of the apparatus,
which is  a rod to which scrapers  are attached ; the water  contin-
ues to flow through  the  filters, and the material is kept  in sus-
pension until the impurities  are washed  away. This involves
some  loss of the  prepared  cellulose, but it  is claimed  that  the
filtration is efficiently and cheaply accomplished.   No details from
disinterested sources are at  hand with reference to the  practical
value  of  either of these  devices, which  seem to  possess  certain
merits.
   * Journal fur Gasbeleuchtung und Wasserversorgung, March, 1883.  The
ratus is figured and described in the Scientific American, April 28. 1883. 
CHAPTER IX.
  ARTIFICIAL IMPROVEMENT  OF NATURAL  WATER {Continued).

                The Softening of Hard Water.
    As  has  already been  explained  (page  33), the hardness of
water is generally due to  the presence of compounds of lime or
magnesia.   While a moderately hard water may be  perfectly
well suited  for drinking, for  almost all the other purposes of a
water supply a soft water is preferable, other things being equal.
If common soap be added to hard  water the  water  seems to
curdle,  but no permanent  froth or lather is formed until, by the
mutual  action of the soap and the compounds of lime (and mag-
nesia) on each other, the latter are  completely converted into a
lime (or magnesia) soap, an insoluble  substance which forms the
curd alluded to.  After this point is reached, any additional soap
becomes available for washing, but the curdy water is less effi-
cient as a detergent.  Hard water is, as a  rule, much less desir-
able for culinary purposes  than soft water.  Finally, hard water
is also objectionable on account of  the " scale " which  forms in
steam boilers in which it  is used: in  manufacturing towns this
becomes a matter of great importance.
    Temporary hardness.—The temporary hardness is due to the
presence of carbonate of  lime or magnesia: these compounds
are soluble in water to a slight extent only, but are brought into
solution by  carbonic acid, as has been explained on page 9: it
will be  convenient to  consider them as  existing in solution as
^carbonates.  The temporary hardness  of a  water may be re-
moved in various ways:  in the first place, by adding soap, as is
actually done when an attempt is made to wash with hard water
—a method uneconomical on the small scale, and impracticable
on  the  large scale on account of the expense; in the second
place, by adding ordinary  washing-soda (carbonate  of  soda)—a
method  employed very generally on  the  small scale, but also
impracticable on the large scale on account of expense.  The 
182
WATER  SUPPLY.
chemical explanation  of  the second  method is this:  when car-
bonate of soda is added to water containing bicarbonate  of lime
there result bicarbonate of soda and carbonate of lime ;  the former
is soluble in water and remains  in solution, the latter being in-
soluble  separates as a fine powder.  A simpler  method  still, as
the explanation of the  term " temporary " shows, consists in
boiling the water for half an  hour or more: the ^carbonate of
lime (or magnesia) is  decomposed, losing half its carbonic acid ;
this  carbonic  acid escapes as gas, and the simple  carbonate of
lime separates as a white powder.   On  account  of this action,
carbonate of lime is one of the chief  constituents of boiler  scale,
and a similar deposit forms in the water-backs of kitchen ranges,
and, in fact, in any vessel in  which the water is boiled.   Some
natural waters are so highly charged  with carbonate of lime that
slight agitation  suffices  to drive off the " extra " carbonic acid
and to allow  the  carbonate  to  separate; large  deposits of car-
bonate of lime occur in nature which owe their origin  to  such an
action.  Fig. 41 (from the Scientific American) shows a  portion
of the feed-pipe of a boiler which was  nearly choked  up by the
calcareous matter.
   From a water which possesses temporary  hardness, the car-
                                        bonate of  lime may
                                        be caused to deposit,
                                        and  the  water thus
                                        become softened, not
                                        simply  by  expelling
                                        the " extra " carbonic
                                        acid by heat or other-
                                        wise, but also by caus-
                                        ing this carbonic acid
                                        to  unite  chemically
with some substance capable of  thus decomposing the bicarbon-
ate.   Caustic soda or caustic potash will  produce this effect, but
the cheapest and most available substance is ordinary lime. The
lime unites with the  extra carbonic acid to form  carbonate of
lime, which settles out as a fine powder along with the carbonate
originally held in solution.  As  carbonate of  lime  is not  abso-
lutely insoluble  in  water, a small amount remains in solution
after the softening has been completed, not enough, however, to
be seriously objectionable.
 
SOFTENING OF HARD WATER.
183
    The  use  of lime was invented  and patented about the year
 1844 by Thomas Clark, professor of chemistry in the University
 of  Aberdeen, but the patent expired long since.  The process
 has been  used  in England at  works  furnishing as much  as
 1,000,000 gallons daily.  The proper amount of lime is added in
 the form of lime-water or milk of lime.  After thorough mixing
 the water  is allowed to subside for  from 12 to 24 hours, and
 drawn off  from  the  sediment.   The  readiness with which the
 finely divided carbonate of  lime settles depends somewhat upon
 the character  of the water ; and,  as it settles, it  drags  down
 with it  and removes from the water a not inconsiderable pro-
 portion of the organic  matter  present;  if the water is  colored
 by peaty matter, a very appreciable  decolorization  is effected.
 Experience,  however, would seem to show that the process gives
 the best results  with water which is naturally  clear, such  as
 spring water; and, in the case of  turbid river waters,  the soft-
 ening process should be followed by  filtration.
    The economy of the process and the advantage of softening
 a hard water on the large scale, rather  than by the use of soap in
 the household, is evident when we consider  that, to soften  a
 quantity of water requiring one hundred-weight of quicklime, the
 expense of materials  would be (approximately):

         1 cwt. of lime, say............................. .. $ 0.50
         5 cwt. of sal soda (at 1.2 cents per lb.)..............   6.00
         20 cwt. of soap (at 6£ cents per lb.).................  130.00

 Of course,  on a large scale the  cost of  labor, and especially of
 handling the sludge, may make the actual difference less than the
 theoretical, but, in any  event, the saving in soap by  the use of
 the softened water is very great.
    On account of the difficulty with which the carbonate of lime
 settles in waters  containing much organic  matter,.of the length
 of time required  and of the necessarily large area of settling-
 basins, the  process is seldom carried out according to the original
plan.   There are  various modifications of the process which aim
to accomplish the object with greater economy of time and space,
using,  however,  the  same material.   These modified processes
involve some form of filter by which the precipitated carbonate
of lime  may be removed at once without waiting for the sub- 
184
WATER SUPPLY.
sidence to take place.   It will suffice to describe one  of these
processes.
   In England a number of manufacturing establishments and
several  towns have introduced Clark's  process  as modified by
J.  H. Porter, C. E.*  The  lime is  employed in the  form of  a
saturated solution, and the mixing with the bulk of the water to
be softened takes place in a separate tank from that in which the
solution is prepared.  When thorough mixture has been effected,
the liquid is at once filtered through  cloth.  The arrangement
and construction of the  tanks varies with the quantity of water
                            Fig. 42.

to be softened.  Fig. 42 represents an apparatus for treating 300
gallons of water per hour.   The preparation  of  the  lime-water
   * The Porter-Clark Process for the Softening, Purification and Filtration of Hard
Waters, by John Henderson Porter, London. 
SOFTENING OF  HARD WATER.
I8S
takes place in the left-hand cylinder, which  is furnished  with a
mechanical stirrer; the  mixing takes place in the right-hand
cylinder ;  the other details of  the apparatus are  evident  from
the figure. The filtration of the mixture may be  accomplished
by any one of a variety of filter presses; that employed  by Mr.
Porter is  shown  in Fig. 42 and more  plainly in Figures 43, 44
and 45.   Fig. 43 shows a portion of the filters used by the  Lon-
                           Fiu. 43.

don  and North-western Railway Company at Liverpool,  where
over 200,000 U. S. gallons of water are softened daily.  Each
filter is made up of a series of cast-iron plates and cast-iron open
frames of the form shown in Figs. 44 and 45.  " Over these filtering
Fig. 44.                          Fig. 45.
chambers, of about I inch in thickness, is dropped (as a towel plac-
ed upon a towel-horse) a cloth of superior quality of cotton twill,
having worked in it holes to correspond with the holes through the
upper corners of both water-space frame and filtering chambers.
When  these  alternate water spaces  and filtering chambers with 
186
WATER  SUPPLY.
the cloths are tightly pressed together  by a powerful end screw,
it will be seen that the holes become, collectively, tubular chan-
nels of the length of  the ' battery,'  the channel of the one side
admitting its chalky water to the circular water-spaces, whence,
being inclosed and under pressure,  it  can  only escape through
the adjoining cloths into the concentric and radiating grooves
which conduct it by a small  outlet to the channel on  the other
side."
   In the figure (Fig. 43) the left-hand filter is represented as un-
screwed and with two of the cloths raised for purposes of clean-
ing.  The cloths are readily removed and replaced by a fresh set as
often as may be necessary—how often depends upon the amount
and the  character of  the impurity,  other  than the chemically
formed  chalk,  present in the water.   At Liverpool and  other
places where the waters are from deep  wells in  the chalk or red
sandstone, the filters  run for 15 hours without  changing  the
cloths and the labor of one man is found sufficient  to cleanse
cloths, and filters and to attend to other details of the process in
softening 150,000 to 180,000 (imperial) gallons for the day's work.
In other places, where the water contains a larger proportion of
magnesia or surface impurities, the filters may not  run for more
than 6 or 7 hours without cleansing.
   From  the application of  Clark's process, in whatever  form,
there results a large quantity of chalk or "whiting," more or less
pure according to the  amount of impurity in the water softened.
If the water contains organic matters, a portion is precipitated
along with the chalk,  together  with any  sediment  which  the
water may contain.  In some localities there is a market for the
whiting which tends to offset  the expenses of  the process.  A
portion might be burned into lime and used over again in soft-
ening afresh portion of water, but being in a fine powder it could
not be burned in ordinary kilns.
   Permanent  hardness.— The  permanent  hardness  is usually
caused by the presence of the sulphates (or other soluble salts)
of lime and magnesia, gypsum (sulphate of  lime) being the most
common; the action on  soap is the same  as that of the bicar-
bonates, which has  been discussed under temporary  hardness.
Water containing sulphate of lime  may be softened  by adding
carbonate of soda, and this  is the method  commonly employed
in the laundry   The chemistry of the process is this:  when car- 
TREATMENT BY  CHEMICAL PROCESSES.         187
bonate of soda in solution is mixed with sulphate of lime in solu-'
tion, there are formed carbonate of lime (which settles out  in the
solid  form) and sulphate of soda (which  remains dissolved);  a
similar action takes place with other soluble compounds of lime
and magnesia.  The expense of this treatment makes it imprac-
ticable to soften, in this way, the entire water supply of a town,
a large portion of which is used for purposes where  the hardness
of the water is a matter of indifference.  We have seen (page 5)
that sulphate of lime becomes insoluble in water at high tem-
peratures and contributes  to  the  formation of  scale in  steam-
boilers ; hence, for technical purposes, it is desirable to remove
the sulphate, and the process just indicated, or some other method,
may be employed to advantage.

            Treatment by  other Chemical Processes.

   On the large scale, attempts are seldom made to improve a
natural water  except  by processes which have already been de-
scribed ;  there are, however, a number of substances which may
be used to advantage in  purifying the small quantity necessary
for drinking in localities where no really drinkable water  exists.
One of  the longest used and best known substances is common
alum, which is often added to a turbid water.  Where the water
contains carbonate of lime in solution, a chemical  action takes
place between it and the alum, resulting in the formation of sul-
phate of lime, which remains dissolved, of carbonic acid, which es-
capes as gas, and of hydrate of alumina, which separates out as a
solid. As the hydrate of alumina forms and settles down, it entan-
gles and drags down with it the finely divided suspended matter
to which the turbidity is  due : in fact, it enters into  some sort of
chemical combination with some of the dissolved organic matter
which  is  thus removed.  When  the water does  not contain
enough carbonate of  lime or other substance capable of  decom-
posing the aliim, the  addition  of the alum  may  be followed
by the addition of a proper amount of carbonate of soda.  Per-
chloride (or other soluble persalt) of  iron  acts very similarly to
alum.  Instead of hydrate of alumina, it is the  hydrate of iron
(ferric hydrate) which is formed, and this also, in settling,  carries
with it  some organic matter.   It was at one  time  proposed to
treat  the water of the Seine  at  Paris with alum, and the use of 
188
WATER  SUPPLY.
perchloride of iron and carbonate of soda were talked of for ren-
dering potable the water of the Maas in Holland.
   Another substance which has more recently come into notice
is  permanganate of potash.   The action is the same as that de-
scribed when discussing the use of this substance as a  means of
determining analytically the amount of organic matter  present
in a water.  (See page 37.)  In attempting to purify an  impure
water by this  means, the highly colored solution of the perman-
ganate must be added in quantity sufficient to impart  a pink
color, which remains permanent  for from five to ten minutes.
The  permanganate,  in  destroying the  organic  matter, is itself
decomposed, and oxide (or hydrate) of manganese separates as a
finely divided solid.   This may be removed by filtration, or it
may  simply  be allowed to settle to the bottom of the tanks in
which the water is treated.  Other permanganates may be used
as well as that of potash.  For the treatment of the water which
the British army was likely to  meet with upon  the Gold Coast,
Professor Crookes,* in  1873, recommended a mixture of

                   1 part of permanganate of lime,
                  10 parts of sulphate of alumina,
                  30 parts of fine clay.

He stated that this  mixture, when added to London sewage in
the proportion of 20 to 10,000, afforded a very satisfactory puri-
fication.
   The most simple manner  of treating a water known  or sus-
pected to be impure  is to boil it,  although it is by no means cer-
tain  that  immunity  from harm  is thus, in  all  cases, assured.
There is, however, evidence to show the value of the treatment;
if, after the boiling, the water is iced, it becomes, of course, more
palatable.  It  is  stated that the Chinese and Japanese drink no
water that has not been boiled ;  and when we consider  the un-
sanitary conditions which exist in those countries and the char-
acter of the water used, it seems as if boiling  the water must
prevent ills that would otherwise befall the people.
   In some instances lime has been added to water which is used
for domestic supply—the lime being added for purposes other
than the softening of a water containing the bicarbonates.   Thus
in Australia, at Sandhurst, Victoria, the impounded surface water
Chemical News, xxviii (1873^ p. 244. 
DISTILLATION.
I89
which is used contains at times as  much  as  30 or 40 grains of
yellowish-brown  clayey matter in the (imperial) gallon, i.e., say
about 50 parts in 100,000.  Here  it was found that sand filters
did not  thoroughly intercept  the  clay in suspension, and that
the water, after filtration, still remained cloudy and opalescent.
Lime was added at the rate of 7 grains to the (imperial) gallon,
and after standing 10 hours the water became  clear: five-sevenths
of the added lime went down with the precipitate, the other two-
sevenths remained in solution  in the water, and of course gave
it a slight hardness.  At several other works lime is used in the
same  proportion, and  this treatment is, in some cases, followed
by filtration, in others not.  The  capacity of one of the works
where this treatment is employed is as great as 1,000,000 imperial
gallons per day.*
                         Distillation.
   The  ordinary process of distillation is sufficiently  familiar.
When water is boiled, the gaseous substances which it holds in
solution  are  expelled almost completely, either while the water
is heating up to  the  boiling point, or with the first portion of
the steam:  the dissolved solids, on the other hand, remain be-
hind while the water  evaporates.  If the water be boiled in  an
                            Fig. 46.

ordinary still—such,  for instance,  as  is shown in Fig. 46—and
the steam  be  subsequently  condensed, the water which issues
from the condenser will be tolerably pure, especially if the first
* Brady :  Froc. Inst. Civ. Eng. Gr. Br. lvi, p. 134 and foil. 
I90                   WATER  SUPPLY.
portions be  rejected and the evaporation be not carried too far.
Distillation is, of course, a somewhat expensive process, for be-
sides the cost of the necessary apparatus, each pound  of water
evaporated requires the consumption of from one-twelfth to one-
seventh of a pound of coal, according to the quality of the coal
used and the efficiency of the boiler employed.  On this account,
distilled water for drinking, cooking, and other domestic uses is
seldom prepared on  any considerable  scale except  on  shipboard.
Here, the steam is usually taken from one of the boilers used to
generate steam for the motive power of the ship,  and the differ-
ent systems consist in differences in the condensers (aerators and
purifiers),  although the term " distiller " is  often applied to this
part of the  apparatus.  The condensers are of various forms—
the ordinary worm, the flat worm or zigzag, and  the tube  con-
denser, consisting  of a cylinder with  tubes inside  running verti-
cally, the  steam passing through the  tubes and the water being
on the outside, or vice versa.
   Ordinary distilled water has  a flat and nauseous taste, owing
partly to the fact  that  the dissolved  gases, notably oxygen and
carbonic acid, have been expelled, and partly to the presence of
certain  volatile organic compounds  which  have been formed
during the distillation.  This is often remedied by allowing the
water to remain for from  10 to 15 days in partly filled tanks
where it will be  exposed to the air and more or less agitated by
the motion of the ship.  A number of devices have been  con-
trived and patented which  aim to  accomplish this aeration and
oxidation  at once, and thus to produce a distilled water fit for
immediate use.
   In the United States navy, a condenser invented  by Passed
Assistant Engineer G. W. Baird  is largely used.   The  essential
feature of this system is the introduction of air into the apparatus
in such a way that it mixes with the steam, and the water which
forms is condensed in  the presence of an abundance  of oxygen,
and thus becomes  fully aerated.  It is  further claimed that the
air so introduced oxidizes the organic matter carried forward by
the steam.    This  it  no doubt does, if not at once, at  least when
the water, thus aerated, is  subsequently passed through a filter
of purified animal  charcoal.   Fig. 47 represents the condenser in
section.   The steam  enters  at a  and, on the principle of an
injector, draws  air in  through b; the  mixture of air  and steam 
DISTILLATION.
I9I
enters the system  of cooling pipes B, where the  steam is con-
densed.  The pipes  are usually of cylindrical section and  are
Fig. 47. —Baird's Condknskr.
made of tin or tinned copper; they  are coiled into helices, the
ends terminating in the common T-heads, C, C, at the upper and
lower ends respectively.   The refrigerating water enters at d and
is discharged at c, and the  condensed water flows out at f and
thence  passes to  the filter.  In the  U. S. navy the water is net
salified and is regarded  as  perfectly wholesome.  It is stated *
that in the Russian navy there  is added to each 1,000 liters of
distilled water  a mixture consisting  of 4.8 grams salt, 3.4 grams
* Fonssagrives : Hygiene et assainissement des villes ; Paris, 1874, p. 316. 
192
WATER  SUPPLY.
sulphate of soda, 48  grams bicarbonate (sic) c * lime,  14 grams
bicarbonate of soda, and 6 grams carbonate of magnesia.
   The British navy uses Normandy's system, and essentially the
same apparatus is used in the German navy, as shown in Figs.
48 and 49 * The apparatus consists essentially  of two cylinders,
the two sectional views of B being taken at right angles to each
other.   Steam is  generated in a  separate boiler and enters the
cylinder A through the pipe d, and passes into the sheaf of tubes
                                     b which are  surrounded
                                     by water which is to  be
                                     distilled.  The watei
                 Fig. 48.                       Fig. 49.
formed  by condensation collects in the reservoir e at the base
of the sheaf of pipes, and from  here  it flows into  the vessel g,
shown only in Fig. 48; if the water is required warm, it may bt
* Fischer : Chemische Technologie des Wassers. p. 205 and foil. 
DISTILLATION.
193
drawn from g directly, otherwise  it flows through a connecting
pipe into the lower sheaf of tubes in the  cylinder B.  The level
of the water in A—which flows in from B—is so regulated that
the steam which is formed may free itself from  any salt water
which it  carries mechanically,  by  passing first through the  per-
forated copper plate a, and then by striking against c, before it
passes through the pipe m into the sheaf of tubes n in the upper
part of the cylinder B.  The water which is here condensed flows,
for further cooling, into the lower  sheaf of tubes in B, into which
the water condensed in b also flows, and which is the set of tubes
with which  the cooling water entering at i  comes in contact.
The water, thus fully cooled, is either discharged directly through
the tube r, or is conducted through s to a simple filter filled with
animal charcoal.  The water used  in  cooling enters through the
tube i and flows off through k, except so much as is necessary to
keep the level of the water in A at the proper height.   The air
which escapes from the water as it becomes warm  is conducted
through  the tube t  into the  steam space of the distilling ap-
paratus, in order that the water, as it condenses, may dissolve it
again and thus become more palatable.  By means of the con-
nection y the return steam from the steam pump may be allowed
to enter A, to be utilized in the production of distilled water.
Finally, when the water in the  distilling  apparatus, A, becomes
too concentrated, it may be withdrawn by means of a cock not
shown in  the figures.
   While distilled water is seldom prepared on a large scale ex-
cept on shipboard, there are some  localities where drinking water
cannot otherwise be procured, and distillation must be resorted
to.   For  example, the island  of  Walcheren,  in  Holland, is de-
pendent for its supply of fresh water for drinking on the rainfall,
all other water being brackish.   For the supply of ships leaving
the harbor of Flushing (Vlissingen), it has been necessary to have
recourse to  the condensation of steam, as being the only avail-
able source of fresh water independent of rain; Normandy's ap-
paratus is employed.   It is stated *  that the plant cost 20,000
Dutch florins (about $12,000), and  that 18 kilograms of distilled
water are produced for each kilogram of  coal burned, the water
being distilled at the rate of one cubic meter per hour and being
of satisfactory quality.
               *Proc.  Inst. Civ. Eng. Gr. Br., lxii, p. 408.
           13 
CHAPTER X.
               SOME GENERAL  CONSIDERATIONS.

                      Quantity and Waste.

   Whatever source  may be chosen for the supply of a city or
town, it  is essential that  the quantity of water  should be suffi-
cient for the needs of the population for a  number of years.
The experience of many places  has been similar  to that of New
York City.   Within eight years after the completion of the Cro-
ton aqueduct, the New York Water  Department wrote :  " This
Board warns the City Council, and through it every citizen, that
every drop of water which the  works in their present  state can
supply is now being delivered in the  city."  What  is, however, a
sufficient quantity ? The following  table gives  the amount of
water  per head of population consumed in certain European
cities:

       TABLE XXVI.—Consumption of Water in European Cities.
Cities (iS
Glasgow.
Paris........
Edinburgh..
Dublin.....
Hull .......
Birmingham,
Blackburn...
Leeds.......
Liverpool . ..
Manchester .
Sheffield ....
Daily Average Supply	
PER HEAD, IN	
U. S. Gallons.	Litres.
60	227
50.2	iqo
48	181
45-6	172
39-2	148
30	"3
30	"3
27.9	107
27	104
24	9i
21.6	82
Cities. +
Karlsruhe......
Bonn.........
Hamburg.....
Dresden.......
Frankfurt a. M.
Coin.........
Altenburg.....
Braunschweig .
Bamberg......
Kassel........
Hannover......
Altona........
Leipzig.......
Daily Average Supply
    per head, in
U. S. Gallons. Litres.
154
 76
 63
 60
 59
 53
 43
 4i
 39
 33
 3i
 3i
 23
58i
289
237
228
223
200
163
154
143
124
116
H5
 86
   The  estimates  of European experts  as to the amount  of
water necessary  for an adequate supply must be received with
* Brackett: Journ. Assoc. Eng. Soc, I (1882), p. 261.
f Grahn :  Journ. f. Gasbeleuchtung u. Wasserversorgung, xx (1877). 
QUANTITY AND WASTE.                 195
some caution  as applied  to  American circumstances, owing to
difference in a variety of conditions.   The following table shows
the actual consumption in a number of American cities:'"'

       TABLE XXVI.—Consumption of Water in American Cities.
American Cities,
Fall River..
Providence .
Lowell.....
Cambridge..
Brooklyn . ..
Philadelphia
St. Louis ..,
Cincinnati .,
New York..
Boston.....
Chicago... .
Detroit----
Year.
1880
1881
1880
 < i
1879
18S0

1881
1880
1881
Population.
  49>43Q
 102,500
  59.485
  52,880
 566,689
 847,542
 346,000
 256,708
1,206,590
 416,000
 503.304
 118,000
Average Daily	Gallons
Consumption.	per head
Gallons.	per day. 30.I
1,448,247	
3.716,937	36.3
2,252,197	37-9
2,472,108	46.7
30,744.590	54-2
57.707,082	68.1
24,958,000	72.1
19.476,739	75-9
95,000,000	78.7
38,214,900	92.
57,384,376	114.
17,926,377	151-9
 Litres
per head
per day.

  114
  137
  143
  177
  205
  257
  273
  287
  297
  343
  431
  574
    From this table it  is evident that there is a great difference
in the amount of water consumed in different places, and if from
30 to 50 gallons suffice in certain cities, the  use of 90 or 100
gallons in others presupposes a considerable waste: in fact, it is
generally agreed by those in charge of water  supplies that from
a quarter to one-half of the water furnished is actually wasted.
Mr. Thos. J. Whitman, of the St. Louis water works, said, a few
years ago, that  it cost  the city fully  $300,000 annually in  fuel
alone to simply supply the waste, and similar statements come
from  all large cities.  For domestic and  household  uses 20 gal-
lons per person per day is  a  sufficient  allowance: taking  into
account the water  used for manufacturing and  mechanical pur-
poses, that necessary  for  street sprinkling, extinguishing  fires,
for use in stables, etc., 60 gallons per  day for  each inhabitant is
a liberal quantity in the case of large cities and manufacturing
towns.   In the  case of the smaller, non-manufacturing towns 35
or 40 gallons should suffice.  Mr. Dexter Brackett, in a valuable
paper on the waste  of water, from which Table XXVI  and a
part of Table XXV have  been taken, considers 50 gallons per
head  as sufficient to provide for all the  demands of the largest
cities of the country.
    The  great waste  which takes place being  acknowledged, the
* Brackett: Journ. Assoc. Eng. Soc, I, p. 261. 
196
WATER SUPPLY.
question arises how to prevent, or at least diminish  it.   There
are two general methods which suggest themselves.  The first is
a rigid system of inspection in order to detect all leakage from
the pipes and from imperfect fixtures, as well as all unlawful use
o( the water; the second is the  general  and compulsory intro-
duction of meters.  With reference to the  first method, although
the authorities in charge of  the distribution of water reserve the
right  to  inspect  the fixtures at any time, yet  such inspection is
annoying and repugnant to the  average  householder, and the
system admits of abuse.  A modification of this system, which
obviates the necessity of entering the building except in cases
where abnormal use of water is already known to exist, is  that
devised by  Mr. G. F.  Deacon, Borough  Engineer,   Liverpool,
England.*   The  following  description of the  system is taken
from  a report on waste of water made to the City Council of  Bos-
ton, Mass.+
   " In the Deacon system the waste-water meter is used to locate
sources of waste.  This meter does not, like the ordinary meter,
record the number of gallons consumed, but it indicates the rate
of flow at any given  time, and whether the discharge is due to
steadily flowing  waste, or to intermittent  and ordinary use.  It
therefore enables the observer to determine,  by observations
taken at  those hours when no water,  or a very small quantity, is
used for  legitimate purposes, whether waste is going on.
   " The meter  (Fig.  50) \  consists of a hollow cone, having its
small end upwards, and containing a composition disk, of the same
diameter as the small end of the cone.   A vertical spindle, attached
to the upper surface of this disk, is suspended by  a fine German-
silver wire, which passes, practically water-tight, through a small
hole in  the top of the chamber, over a pulley, and  supports a
weight.   This weight is so adjusted as to  retain the disk at the
top of the cone  when the water is at rest.  When any water is
drawn through the meter, the disk is  pressed downward towards
the bottom of the cone, its position depending upon the amount

   * A valuable report of Mr. Deacon is reprinted in the Report of the Cochituate
Water Board of the City of  Boston, for the year  ending April 30, 1874. City Docu-
ment No. 55, pages 84-112.
   f Reporton Waste of Water (May 25, 1882). Boston City Document No. 78,1882.
   X Figure 50 is reduced from a plate in a paper on The Constant Supply and
Waste of Water, by Geo. F. Deacon, in the Journal of the Society of Arts, May, 1882. 
FOUR  INCH  DEACON  WASTE  WATER METER.
Inlet.
Outlet.
Gauge Cone.
Disk.
Stem of Disk.
Guide for Stem.
Wire connecting
  Disk with Pen-
  cil Carriage.
Gland   with
  Bushes.
Pencil Carriage.
Counter balance.
Clock.
Drum  carrying
  Paper.
0  113   4   I  S  7   I   9  »  It  IZlNCHa
Fig. 50. 
198
WATER  SUPPLY.
of water  passing  through the  meter.
O, Jo
                                       By  means  of  a pen-
                                       z cil  attached  to the
                                       1? wire the motions of
                                         the disk are record-
                                         ed on a drum, which
                                         revolves by  clock-
                                         work,  once  in  24
                                         hours.
                                             " A  fac-simile,
                                         about   one-fifth
                                         full size, of  a dia-
                                         gram  drawn  auto-
                                         matically by a
                                         waste-water  meter,
                                         is shown in Fig. 51.
                                         It  is obvious that
                                         when water is being
                                         drawn  off for use
                                         the  rate  of flow
                                         from minute  to
                                         minute must be va-
                                         riable ; and  this is
                                         accordingly  shown
                                         by  the  irregular
                                         vertical  lines from
                                         noon to midnight,
                                         and from 4 A. M. to
                                         noon.  When con-
                                         t i n u o u s—that is,
                                         preventable,  waste
                                         alone is taking place
                                         —the flow must evi-
                                         dently be uniform;
                                         and this condition
                                         is indicated  by  the
                                         comparatively uni-
                                          form and horizontal
                                       * line  from  1 to 4
a.m.. only occasionally broken by vertical  lines, caused by persons
drawing water during the night.
 
QUANTITY  AND  WASTE.
I99
    "The meter is placed in a box under the sidewalk or roadway,
 and so located as to control the flow of  water supplied  to a cer-
 tain district, the limits of which have been previously determined.
 All the water used  in this district  is  drawn through the meter,
 and the quantity and rate recorded.  After a few diagrams have
 been taken, to show the ordinary rate of consumption, inspection
 is commenced.  Every service pipe is  provided with a stopcock,
 which is accessible from the sidewalk by  means of an iron wrench
 about seven feet long.  When this  wrench is applied to the stop-
 cock the sound caused by water passing  through the service pipe
 can  be easily distinguished.  When no noise is heard, with the
 stopcock fully open, it is partly closed, and the increased velocity
 always causes a distinct  sound, although the  quantity of water
 passing the stopcock may be very  small.  A night inspector be.
 gins his work about midnight, and tests, by means of his shutting-
 off wrench, each service pipe.  If he discovers any flow through
 the service pipe, the stopcock is closed,  and a note made of the
 time and the number of the house.   He continues this operation
 through the district until about 4 A.M., when  he retraces his
 steps, and  opens all the stopcocks  he had found wasting.   Dur-
 ing this time the  meter is  recording the consumption, and the
 diagrams  show the amount of water wasted by each of the ser-
 vice pipes that were closed, the time the  inspector began and
 finished his work,  and the time each stopcock was closed.  The
 day  inspector receives the  night  inspector's  report,  visits the
 premises where waste  was noted, and ascertains the cause.  In
 cases of waste from  defective fixtures  the owners are notified to
 repair  the  same, and the visits  are continued until the notices
 have been complied  with.
   " The economy of this system, as compared with house-to-
 house inspection, is apparent.  The attention of the inspector is
 at once directed to  the place where the waste is going on, and
the time lost in indiscriminate inspection is saved."
   The Deacon system has given very satisfactory results where-
ever tried.   The chairman of  the  Liverpool Water Committee,
in his address in 1879, sa'^ :
   "We have given  the city a constant service* of water, with a
   * Before the introduction of the Deacon system of inspection, the supply of Liv-
erpool was an intermittent one, the water being on only 9^ hours out of the 24. 
200
WATER  SUPPLY.
decline  in  the  death-rate, and  it now remains for me to show
what  other effects have arisen  from the change of system.   In
the year 1871  we delivered  an average of 122,000,000  gallons
weekly ; in 1880 our deliveries will be about 115,000,000 gallons;
and this, notwithstanding an increased sale for trade purposes
of 12,250,000 gallons weekly, and an  increased population of
104,000.  The saving has been so great as to meet the increasing
demands of the city and district for eleven years.
   "The change to constant service has already yielded nearly a
quarter of a million of money (£250,000), and the ultimate saving
to the rate-payers, when the  7,000,000 gallons per week  yet un-
sold are absorbed, will be £50,000 per annum."
   The  conditions under which this  system of waste  detection
has been tried  in  Glasgow correspond  more nearly with those
existing in Boston and  other American cities, than do those of
other European cities where the system has been  used.  The
supply furnished is constant  and ample, and the proportion of
water fittings to the  population is larger than is common in most
European cities.
   The  following table  (Brackett) shows the results obtained in
Glasgow from an inspection similar to the one made in Boston:
TABLE XXVII.—Waste Water Inspection in Glasgow.
CO		& H	X B.	Gallons per Head per Day.				
	3	U X	u 0 P. H					
								
	It °5			At starting of meters.			After first three inspec-tions.	
	X H w£2		w in M					
								
CO	0 0	3 a.	0 Z <->			Night rate		Night rate
	D		& <r. <->	Total.		per	Total.	per
55	£	S3	£			24 hours.		24 hours.
I	9	14,972	25-8	71.O		540	40.9	21.1
II	6	10,002	22.4	79	0	72.2	50.4	33-o
III	3	4,986	35-4	73	7	62.4	44.2	21-7
IV	6	7,629	30.6	79	0	57-o	50.5	24.8
V	7	9.815	37-8	55	1	36.8	37-7	17-3
VI	8	12,614	39-7	37	2	29-5	27.1	17.8
VII	2	4.132	25-5	45	5	30.6	41.9	25.8
VIII	3	6,306	37-1	44	9	27-5	33-6	i5-i
IX	4	7,821	32.1	44	9	3i-7	30.8	15-2
X	2	3.012	34-6	44	2	33-4	25.0	12.8
								
averages.	50	81,289	30.6	55-8		45.2	38-4	21.0
The results of a  trial  of the Deacon system on a portion of 
                   QUANTITY AND WASTE.                201

the water service of the city of Boston, Mass., are shown in the
following table (Brackett).
TABLE XXVIII.—Waste Water Inspection in Boston, Mass.
		1 1	Gallons per Head per Day.						
		u 0							
Number of	z o	'-fe				After two or three		Reduction.	
	£2	O « H K B, W CO * g g 8	Before inspection.			inspections.			
Section.			Total.		Night rate per 24	Total.	Night rate per 24	On total.	On night rate.
	w	£			hours.		hours.		
I	2,8lO	9.2	53-5		39-1	26.4	10.6	50.7	72.9
I andiA	3.675	9.1	52		39-0	34-1	13-7	34-4	64.9
2	2,170	8.1	49	9	33-1	36-7	13-2	26.5	60.6
3	2,030	6.2	71	8	43-2	45-'	20.2	37-2	53-2
4	1,880	5-9	68	4	42.2	47 8	22.3	30.1	47.2
5	1,790	5-9	72	7	53-3	47.8	17.8	34-3	66.6
6	1,875	7.2	60		44.6	35-3	I5-I	41.2	66.1
7	2,540	6.8	55	2	3i-9	39-6	19.2	28.3	39-8
8	2,400	6.6	55		40.8	37-9	18.5	3i-i	54-7
9	2,150	5-5	62	9	40.1	36.2	13-7	42-4	65.8
IO	1,790	5-6	52	3	28.1	46.1	18.7	11.9	33-4
n	2,800	6.5	43	7	17-5	25.7	9-5	41.2	45-7
12	2,300	7.6 6.86	80	4	55-2	31.2 37-7	12.5 15-8	61.2	77-4
Averages			58	5	37-5			35-6	57-9
    From the above it appears that on the whole district covered
 by the inspection, containing a population of 21,760 persons, the
 average daily consumption was reduced from 58.5 to 37.7 gallons,
 a saving of 35.6 percent, or 20.8 gallons for each person supplied,
 while the  night  rate was reduced from 37.5 to 15.8 gallons per
 head per day, a saving of 58 per cent.   The Boston experiments
 being continued  for a short time  only, seem to have cost more
 than the value of the  water saved ; this  is not the case where the
 system forms a part of the regular operation of the water works.
    The Cincinnati Board of Public Works use a device invented
 by  Mr. Thomas  J. Bell,  the  Assistant Superintendent of the
 Water Works, which takes advantage  of  a  fact  long known,
 namely, that it is possible to detect  a leak by taking advantage
 of the conduction of the sound caused by that leak through the
 metal pipes by some  metallic connection, to the ear.  Mr. Bell's
 device  consists of  a  diaphragm inclosed in a hollow piece of
wood, shaped like a telephone, and about the same size.  A piece
 of iron extends through  the middle  of the neck of  the " detect-
 or," one end projected and threaded, and the other communicat-
 ing with  the  diaphragm.  A threaded hole is bored in the top 
202
WATER  SUPPLY.
of the key used to turn water on and off at the cocks on the edge
of the pavements, and, when it is desired  to make a test, the de-
tector is screwed into the top of the key  and  the ear applied to
the detector.  The least leakage or  the smallest  stream  running
from a hydrant can be distinctly heard. Inspections are  made at
night.
   A waste-water  indicator, invented by Mr. Benj. S.  Church,
resident engineer of  the  Croton aqueduct,  N.  Y., is thus de-
scribed in  The Sanitary Engineer, to  the publisher of which we
                                    are  indebted for the use
                                    of the cut (Fig. 52).
                                        " The device  consists
                                    of a pressure gauge, with
                                    arrangements for attach-
                                    ing it to the pipe through
                                    which  water is suspected
                                    of leaking.  Its most ex-
                                    tensive application  is de-
                                    signed  to be  to service
                                    pipes  from street  mains
                                    to houses.  For  this pur-
                                    pose, a special stop-cock
                                    is placed  on the service
                                    pipe under the  sidewalk
                                    instead  of the  ordinary
                                    kind,  and from it a pipe
                                    or hollow stem, instead of
                                    a solid rod, runs up to the
                                     stop-cock box. The shank
                                     of the key, also, is hollow,
                                     and has a pressure gauge
                                     attached at the top.  By
                                     means  of  a  coupling,
turned by a wheel  at its top (shown just below the handles of
the key on either side of the gauge), an air tight connection is
made between the stem and the key.  When the cock is  closed
(by turning the cross-arms, and with them the gauge, which is
fastened to them), a small' port' in  the stopcock plug establishes
a connection between the street main and the gauge ; the air of
the stem  is compressed, and the hand on the gauge indicates the
Fig. 52.—Church's Detector. 
                   QUANTITY AND  WASTE.                203

hydrostatic pressure on the main.  By turning the plug to another
position, a second ' port ' is opened,  allowing the water to flow
through, if there  be any escape from the pipes  in the house.   If
that be the  case, the gauge will indicate a diminished pressure,
depending on the amount of the discharge.  The plug can also
be turned to a third position, leaving it open to the house and
closed against the street.  By this means the approximate height
of the leak (if such is found) is ascertained.  The exact position
of the ports is indicated on a scale with vernier, which slides up
and  down the coupling, to be clamped at the level of the side-
walk for convenience in making reference marks thereon.  The
gauge is said to indicate a flow of five gallons an hour, and ' re-
veal the least leakage even to the size of a  pin-hole.'  The ap-
paratus may also be  applied to street  mains to  detect leaks  in
them." *
   The second general method for checking waste is the universal
introduction of meters.  There can be no question of the justice
and  propriety of measuring the water  used  for manufacturing
purposes or  in hotels and other large establishments.   It is, how-
ever, objected that  the adoption of meters for  private dwellings
will cause an injurious economy in the  use of  water among the
very  class of the population where it  is important that water
should  be used freely.   This objection is obviated  to a great
extent, at least, in  some  places where  meters are employed, by
fixing a minimum  tax—to be paid by all water-takers—which
shall cover a certain quantity, based on a reasonable estimate  of
domestic needs.  Water used  in excess of this quantity is paid
for by measurement, and special arrangements  may be made for
tenement houses and  the  dwellings of the very poor.  It  is
further said  that  the  cheaper meters are not very reliable, that
it is  often possible to pass a considerable amount of  water with-
out its being registered, provided  the water  be allowed to flow
slowly, and  that the meters are continually needing repairs and
giving rise to dissatisfaction and  complaint on the  part of the
water-takers.
   Meters are in  very general use  in Providence and Pawtucket,
R. I., and in Fall River, Mass., having  been introduced with the
water supply: Providence, with 9,780 services  has 4,816 meters,
and consumes 36.3 gallons per head of population; in Fall River
* The Sanitary Engineer, January 18, 1883. 
204
WATER  SUPPLY.
60 per cent, of the services are metered, and the consumption is
30.1 gallons per head.  The introduction of meters is, of course,
much more easy with new works than with works already estab-
lished.  No statistics have come under the author's observation
with reference to the  matter of repairs in those American cities
where the use of meters is anything like general.   The following
statistics are compiled from German sources:
   In Magdeburg it was decided in 1879 to introduce meters
universally, and the water rate was fixed at 33 marks (say $8.00)
per house for any  amount up to 300  cubic meters per annum
(about 215  U. S. gallons per day).  Above  this amount the
charge was  made  at the same  rate, i. e., 11 pfennige  per cubic
meter.  The introduction of meters  was decided upon almost as
a necessity, but, according to  subsequent official  reports, has
been  in  every way  successful.  At  the close  of  the year 1880
there were  2,792 meters in use.  During the  year 168 meters
had required repairs, and 70 had been tested  at the request of
consumers.  The meters are all tested before introduction, and a
record kept  for future comparison.   In Berlin meters are in uni-
versal use.   Eighty-two per  cent of  the water supplied  is
measured and paid for; the remainder includes what is used for
flushing  the pipes, for extinguishing fires, for sprinkling streets,
etc., and also loss by leakage.   Of the  15,853  meters  in  use in
1880-81, 2,093, or 13.2 per cent, were removed  for more  or less
serious defects, the number  registering incorrectly or not at  all
being 1,580, or ten per  cent of the whole  number in  use.   In
Breslau the  number of meters in use in  1880-81  was 5,141 ;  of
these, during the year, 1,085 were tested  by request of the con-
sumer or at the instance of  the inspector.  Of  the  1,085  tested,
740 were found to  need repairs of  some sort, 406 (i. c.,  7.9 per
cent) registered  incorrectly  or not at all.  It should be said that
the error in registering  is  generally to the benefit of the con-
sumer.
   Of the methods indicated to check waste, local considerations
must determine which  shall be adopted.  If  a city " has at its
disposal  150 million gallons daily for a population which does
not consume 30 millions," as is stated to be now the case in Balti-
more, Md., there is certainly no occasion for introducing meters
at all; but  in places where the available  water  is limited  in
quantity, or where, without economy, the  existing  supply  is 
QUANTITY  AND  WASTE.
205
likely to prove insufficient in the immediate future, or in places
where the rates are of necessity high, the introduction of meters
would be advisable.  The  waste in Northern cities during the
winter is enormous, as it  is very common  to  leave the faucets
open during the night, in order to prevent freezing.  This cold
weather waste  can never  be completely stopped until property
owners are  obliged to arrange  their plumbing  so that the water
can be completely drawn from the pipes when liable to freeze.
By the  use  of meters it  can be largely reduced,  as  the waste
would be reduced to  the  minimum amount required to  prevent
the pipes from freezing, and it  would become a question to the
water-taker  whether  it  was economy to waste water or remodel
his fixtures.
   Next in  importance to the special form of waste just alluded
to, is that due  to  defective  or  improper fixtures.   Such sources
of waste may be readily  detected  by  systematic inspection,
and  should  be controlled by municipal regulation, as is indeed
done in  some  cities.   " Providence,  New  York,  Brooklyn  and
other American cities license their plumbers, and  to a  certain
extent inspect  the fixtures  used;  but in English cities the ordi-
nances and  regulations are  much more rigid than those in this
country.  Liverpool,  Manchester,  Glasgow and  other  English
cities test and stamp  all of the  water fittings used.   In Glasgow,
during the year 1877, when  this plan was first adopted, of 4,369
fittings  examined, 14.6  per  cent were rejected, while in  1880, of
27,517 examined, but 3.92 per  cent were rejected.   In the latter
city  certain  varieties  of fittings are proscribed.   When  any of
these are  found wasting water twice during three months, they
are removed, and  their use is  not  allowed at all in new prem-
ises.
   " All  cisterns are provided  with  overflow pipes,  which are
brought outside the building or made to discharge  inside where
they can be seen.  The service pipes, except in special cases, are
required to  be of lead, and  their weight is prescribed.  No pipe
or fitting can be covered until inspected, to see that it conforms
to the regulations.
   " Water-closets and urinals  are not allowed  to be supplied
direct from  the service pipe, but must be supplied from cisterns,
so constructed, that in  water-closets  not more than two  gallons
can be used at  a single  flush, and  in urinals not  more  than i£ 
206
WATER  SUPPLY.
gallons, and so that  they cannot  be made to flow continuously
either by intention or neglect.
   " The adoption of the above or similar regulations in Ameri-
can cities, while not in the least curtailing the legitimate use of
water, would be the  means of preventing a very large proportion
of the present enormous  amount of willful and useless waste." *
   In view of the  difficulty  of  supplying large cities with water
against  which no  complaints can  arise,  the question  is often
raised whether it is not  advisable, in some cases, to  introduce a
double supply.  As the author has  remarked elsewhere:  f "It is
true that for  many  purposes, as  for extinguishing fires and for
sprinkling streets,  a water  would  answer which  would not  be
suitable for drinking, and such  a  supply might in many  cases be
easily procured, while to procure  an abundance of water well
suited for drinking would involve a large outlay.   To the double
system there is  no (sanitary) objection, if  the  poorer water can
be drawn only from street hydrants, which are under municipal
control; but it is not practicable to supply two sorts of water to
private dwellings, with any security that the distinction  between
them will be regarded; no  domestic, and indeed  no average in-
habitant, will fail to use for all purposes that water which is  most
handily obtained,  unless, indeed, it be actually repulsive to the
taste."  It should be said, moreover, that the introduction of a
second  (inferior) water, where works already exist, would often
prove nearly or quite as  expensive as the extension of the exist-
ing works and the increase of the supply of water fit to drink.

                Conduits and Distribution  Pipes.
   Where the source of  supply is at a considerable distance, the
water is usually carried by gravity in brick or other masonry con-
duits to a storage  or distributing reservoir.  Open canals are dis-
advantageous, especially  on account of the liability of pollution,
but also as giving  opportunity  for  considerable changes of tem-
perature and for  vegetable growths.   The water in passing
through a long conduit has some action on the mortar or cement,
and  may become slightly harder ; generally, however, the volume
of water is so great that  there is  very  little perceptible effect.
Except in this respect, the  water undergoes almost no change.
* Brackett, loc. cit.
\ Buck's Hygiene, vol. i. p. 215. 
CONDUITS  AND DISTRIBUTION PIPES.
207
  Even the change of temperature  in  a properly covered conduit
  with constant flow is small,   Thus, Kerner found, in the hottest
  days  of the summer of 1875, that  the water of the Frankfort
  supply  increased in  temperature  from 90 C. to only  io° C, in
  flowing from the source  to  the  main reservoir, a distance of 82
  kilometers.   In passing through the city mains, a further distance
  of six kilometers, the temperature  increased 2°.?$ C*  (Compare
  page 93.)  Where the source of supply is a river or pond, a con-
  siderable growth of the fresh-water sponge is often found on the
  walls  of the conduit for some  distance.   For  this and  other
  reasons, such conduits should be subjected to periodical cleansing,
  if inspection shows it to be necessary.
    The distances of the  sources of supply of various cities is as
 follows:

  Altenburg (springs)......... 15.5 miles.  Munich (springs)........ 24.9 miles.
  Danzig (springs)............ 12.4   "    Paris (River Dhuis)..... 81.4  "
  Frankfort a. M. (springs)... 52.   "    Paris (River Vanne).....107.2  "
  Glasgow (lake)............. 36.   "    Vienna (springs)........60.3  "
  Gotha (springs)............. 20.5  "

  Boston (Lake Cochituate)... 16.   "    New York (Croton River) 40.6  "

    From the distributing reservoir, or directly from the source of
 supply, the water passes into the main distribution pipes, which
 are usually of cast iron.  Although there are some waters which
 experience has shown to have almost no action on cast iron, with
 most waters the pipes soon begin to rust.  The rust often begins
 at  numerous isolated  points, or  nuclei, forming  "tubercles,"
 which increase in size, become merged together and finally—aided
 by  the collection of sediment from the water—nearly choke the
 pipe.  The presence of  iron in the  water, either in solution or in
 suspension, can hardly be regarded as deleterious to health, but
 the water is sometimes rendered unfit for washing and  cooking.
 The presence and growth of the deposit of iron-rust, has,  how-
 ever, a very serious effect on the  flow of the water, and it be-
 comes  necessary to remove the deposit by  scraping the inside
 of the pipes.  Several  special tools have been devised  for this
purpose.  The following  tables (Tables XXIX and  XXX) will
show the effect  of the  accumulation of rust in diminishing the
Wolffhugel:  Wasserversorgung, p. 227. 
208
WATER SUPPLY.
capacity of the pipe and the flow of water: they are the results
of observations made in Aberdeen, Scotland.'"
TABLE XXIX.—Diminution of Available Capacity of Corroded Pipes.
			Internal Diameter.	Amount of	Capacity of		
				Rust per line-	clean Pipe per		Percentage op
No.	Age of Pipe.	Character.		ar Yard.	linear Yard.		Space occupied
							bv Rust.
	Years.		Inches.	Cu. Inches.	Cu. Inches.		
I	20	Uncoated.	3	63.84	254-44		25.O
2	29	«i	3	86.94	254	44	34-i
3	38	"	3	IIO.44	254	44	43-4
4	29	"	4	182.37	452	37	40.3
5	22	"	4	244-37	452	37	54-0
6	14	"	5	180.	706	86	25-4
7	15	Coated.	7	190.	1,385	42	13-7
8	15	"	10	240.	2,827	44	8.4
9	40		15	1,320.	6,361	74	20.7
TABLE XXX.—Discharge from Corroded Pipes.
			Approximate	Head in Feet.		Discharge per Minute.	
	Diam-	Age	Amount of Cor-				
No.	eter OF	of	rosion per linear			Before	After
	Pipe.	Pipe.	Yard.	Before Cleaning.	After Cleaning.	Cleaning.	Cleaning.
	Inches.	Years.	Cu. Inches.			Imp. Gallons	Imp. Gallons
1	3	29	86.99	42	47	47	143
2	3	29	93-	54	56	79	188
3	3	29	93-	70	74	143	200
4	3	32	190.	77	82	16	150
5	3	32	190.	72	72	115	187
6	3	26	80.	56	62	35	220
7	3	26	88.	36	43	65	130
8	4	29	100.	40	45	69	H5
9	4	29	100.	38	42	125	107
   These results are the average gaugings of five different trials taken once a week
on the same day.
   On account of the action of most waters on cast-iron pipes it
is usual at the present time to protect the surface in some way
from corrosion.  The process commonly employed is that devised
by Dr. R. Angus  Smith:  the newly cast pipes, which must be
free from rust, are heated to a temperature of some 5000 Fahr.,
and then dipped  perpendicularly into  a hot  bath  of coal-tar
pitch mixed  with  a  small proportion of heavy coal oil.   In this
bath they are allowed to remain for a short time and then with-
drawn.   The coating thus formed is firmly coherent and is unob-
   * M. B. Jamieson : The internal corrosion of cast-iron pipes.  Proc. Inst. Civ.
Eng. Gr. Br., lxv (1881), p. 323. 
CONDUITS AND DISTRIBUTION  PIPES.
209
jectionable  from a sanitary point of  view.  It does not afford
absolute protection against  rust, but it delays and diminishes the
action of the water to a great extent.   The first line of pipes of
this description laid  in this country was laid in Boston in 1858.
In  1876-77  some of these (20 in.) pipes were removed.   "As
they were taken up their condition was observed.   Their inner
surfaces were not entirely free from tuberculation, but were very
much  more  so than are the surfaces  of  uncoated  pipes in  this
city after they have been laid but a few  years.  The  tubercles
were isolated, and were not in sufficient numbers or of  sufficient
size to very materially interfere  with the capacity of flow of the
pipes.   They were very easily removed—more  easily than from
uncoated pipes—seeming to have very little  hold  upon the tar
surface.
    " Upon cleaning off  the surface under a tubercle one would at
first suppose there had  been simply a deposit, that no action  had
been had either upon the iron or upon the coating; but a more
careful examination would show that  under  the center  of the
tubercle a portion of the iron, from the size of a pin  head to that
of a small pea, had been transformed into a black substance that
could be easily cut with a knife, and had the appearance of plum-
bago.  The inference drawn from the  general appearance of  the
pipes was that they would have lasted for an indefinite period." *
    Some time  since  Professor  Barff,  of London,  proposed to
protect articles of  iron, among  other things  water pipes, from
corrosion, by covering them  with an artificial coating of the black
oxide  of iron.   The  coating  is  produced  by exposing   the
metal  to superheated steam  at a high temperature, and  when
once formed it protects  the iron from atmospheric and  other
agencies which would corrode it.  The process has been some-
what modified and is now known as the Bower-Barff process,  and
promises to become a practical and valuable means of protecting
cast-iron pipes. Some  wrought-iron  pipes  of this description
have been introduced as service pipes in Altona, and  probably
elsewhere, but  it is too soon for definite statements as to their
durability.
    Cast-iron pipes are usually connected  by the hub and  spigot
joint ;  the joints are first  packed with tow  or jute  and then
    * First Annual Report of the  Boston Water  Board.   City Document No. 57.
Boston, 1877.
          14 
2 10
WATER SUPPLY.
melted  lead  is run in and driven up firmly.  It has been found
that the tow sometimes gives an unpleasant taste to  the water,
and  the Rivers  Pollution  Commission recommended that the
joints of  the larger mains should be pointed  up with Portland
cement  on the inside to prevent the water from coming in con-
tact  with  the tow.
   The sediment which accumulates in the pipes, especially in
low-lying  districts, although it has generally a  rusty appearance,
is not simply iron rust from the pipes.   With the iron rust  there
is always more or less earthy matter, and  sometimes the sedi-
ment contains  a large proportion of vegetable organisms, such
as the Crenothrix, already described.  The following results were
obtained  from the analysis of the  rust in  the Aberdeen  pipes
already referred to :
                         From uncoated 4-in. Pipe      From coated 10-in. Pipe
                             21 years in use.           15 years in use.
     Organic and volatile matter.......  16.62                  18.05
     Sulphuric acid (SOa).............  0.60                   1.08
     Phosphoric acid.............. Slight trace                 trace.
     Magnetic oxide of iron...........  32.47                   0.36
     Peroxide of iron.................  9.04                  37-55
     Insoluble sandy matter...........  41.27                  42.78
     Lime...........................  trace                   o. 18
   Wrought-iron pipes, coated with cement inside and out, have
been sometimes used, generally from motives of economy.  They
are made by rolling up sheet  iron and  riveting the edges of the
sheet together as shown in Fig. 54.  A longitudinal rib is some-
times employed as  shown in Fig.  53.   The lengths of pipes may
be telescoped  together, but are usually connected by means  of
an iron sleeve, filled in with  cement.   The  durability of the
                                              pipes is very dif-
                                              ferent in different
                                              localities,  owing
                                              mainly  to dif-
                                              ference  in  the
                                              quality   of  the
                                              workmanship.
                                              Where the pipes
                                              have  been made
                                              under the direc-
tion of the water department, by day labor, they have sometimes
Fig. 54. 
CONDUITS AND DISTRIBUTION  PIPES.
211
 proved very  satisfactory, but  where the work is done by con-
 tract it is difficult always to obtain the best results.
    In the extreme  West, wrought-iron  pipes  are used for con-
 veying water  for hydraulic operations and for purposes of water
 supply, sometimes under a very great head.  Water is  conveyed
 to  Virginia City, Nevada, through such a  main,  the  maximum
 thickness of which  is 0.34 inch, and which is  exposed  in some
 parts of its length to a pressure of 1,800 feet head of water.  The
 pipes are  coated with asphaltum to prevent rusting.
    Wooden pipes, generally bored logs, have been used more or
 less for conveying water, and are still employed in some sections
 of  the country.  Detroit had at one time  130 miles of wooden
 pipe, and 1%  miles  were laid in  1880.  The logs used are sound
 green  tamarack, not less than 6 inches  in  diameter and 8 feet
 long.  The joints are covered  with iron thimbles, and  the pipes
 last for 16 years or more and  cost  (or did cost) only about one-
 fifth as much as iron.
    Service pipes.—The  service pipes for house distribution  in
 connection with a public water supply are generally of lead, this
 metal being employed on account of the facility with which it
 may be worked.  Lead pipes are also  sometimes used for convey-
 ing well or spring water to individual residences.  Various waters
 act very differently  upon lead, some  corroding it rapidly, others
 only to a very slight extent, under similar  circumstances.  The
 cause of the  corrosion is to be sought  in the  dissolved oxygen,
 of which all waters contain more or less, and in certain saline sub-
 stances the presence of which determines a more violent action.
 It  is generally felt,  for  instance, that the  presence of  nitrates,
 nitrites, and ammoniacal salts increases  the action  of  water on
 lead, while carbonates, sulphates, and  notably phosphates, hinder
 such action;  but while certain  general statements may be truth-
 fully made as the result  of laboratory experiment and from the
 analysis of waters whose action on  lead has  been learned by
 experience, it  is a rather hazardous thing for a chemist to pre-
 dict, a priori, what will be the effect of a  particular water on lead
pipe under the conditions of ordinary practice.   Next to no value
attaches to experiments  made by immersing strips of sheet lead
in open or closed vessels containing the water under  examina-
tion.  In  actual  practice,  many waters  which would  be  pro-
nounced dangerous on the strength of  such experiments, prove 
212
WATER SUPPLY.
entirely harmless.   The  pipes very soon become  covered with a
naturally  formed protective coating of difficultly soluble  com-
pounds of lead; and after a slight initial  action, corrosion prac-
tically ceases if the pipes are kept constantly filled.
   If it is felt necessary to make or to have  made  preliminary
laboratory experiments,  they  should be  made  by imitating as
nearly as possible the conditions of actual practice, and sufficient
time should be employed.  The following extract from the report
on the  examination of a soft surface water (where the  time at
disposal was somewhat limited), will serve  as an example: *
   "A  coil of ioo feet  of new one-quarter inch lead pipe was
taken and filled with  the water under examination.  The pipe
held 64 cubic inches of water, and the surface of lead was  equal
to about 900 square inches.  The water was allowed to remain
in the pipe for 50 hours  and then removed, a fresh supply  being
introduced without allowing the air to come  into contact with
the inside surface of the pipe.  The water as drawn was  quite
turbid, from the presence o«f the oxycarbonate of lead, and was
found to contain (the lead being calculated as metallic lead):
                                         Metallic Lead.
                                  Parts per 100,000. Grains in U. S. gallon.
       In solution........................... 0.055          0.032
       In suspension........................ 1-257          ° 733
             Total....................... 1.317          0.765
   " At the end of 70 hours the water in the pipe was drawn  out
and found to contain :                                        *
                                         Metallic Lead.
                                  Parts per  100,000. Grains in U. S. gallon.
       In solution........................... o. 573          o. 334
       In suspension........................ 0.137          0080
             Total...................... 0.710          0.414

   "The  pipe was then thoroughly washed  from  any loosely
adhering coating by allowing a rapid stream of Cochituate  water
to flow through for some time.  The Cochituate water was then
displaced  by the water  under examination, and  this water was
allowed to remain  in the  pipe  for 30 hours.  This water,  when
drawn, contained, both in solution  and suspension, o. 157 part of
metallic lead in 100,000,  or 0.092 grain to the U. S. gallon.  The
   * Report on the Waters of Flax Pond, made to the City Council of Chelsea Mass
1875- 
SERVICE PIPES.
213
amount  in suspension was not determined  separately, as there
was no very considerable  quantity visible to the eye.  A fresh
portion was allowed to remain in the pipe for 40 hours, and then
contained in solution and suspension 0.184 part in 100,000, or
o. 107 grain to the U. S. gallon."
    At the conclusion of the experiment the action on the lead
had not ceased, even practically, but it had diminished very much,
and there was  no doubt that,  in practice, the water  would act
very slightly on the pipes when in continuous use, as has proved
to be the case  in Boston,  New York, Glasgow, Manchester, and
many other places where the question has been discussed.
    It may be said that, while with most waters the action on the
lead practically ceases, it probably never ceases absolutely.  The
water of Lake Cochituate,  as supplied in Boston, Mass., through
lead pipes,  always  contains traces of  lead in solution.  The
amount of lead taken up by the water in passing through some
150 feet  of pipe which had been in use for some years, was found
to  be  only 0.03  part in 100,000, or less than 0.02  grain in the
U. S. gallon.  Water which is  allowed to remain in the pipe for
some time, or is  drawn from the hot-water  faucets,  may contain
as much as  o. 1, or even 0.2 part  in 100,000 (from 0.06 to o. 12
grain in  the gallon), and wherever  lead distribution  pipes are in
use, it is safer always to run to waste enough water to clear the
pipes, and never  to use, for drinking or for cooking,  water which
has passed through the  pipes while hot.  A similar precaution
should be used in  the  case of  new pipes: the  water should be
wasted intermittently but  freely for a number of days.  There is
great difference in the susceptibility of different persons to lead
poisoning. It is thought that as little as one-fortieth of a grain to
the gallon has caused sickness, but one-tenth  of a grain is  usually
regarded as an outside limit.  It is doubtful whether there  are any
well authenticated  cases of lead poisoning  from the  use of the
Cochituate water.*  The  Croton  water supplied to New York
city is similar to the Boston water in its action on lead,f although
at least one case of poisoning has been  reported, which was sup-
posed to be due  to the daily use for some time of water which
had stood over night in the pipes.  The practical experience in
* See Report of the Mass. State Board of Health, 1871.
f See Report of the Metropolitan Board of  Health, New York, 1869, p. 420. 
214
WATER  SUPPLY.
the use of lead pipe in the cities mentioned, and in many others,
shows that, as a rule, there  is no danger in using lead pipes for
house distribution in connection with a public supply.
   The most  unfavorable situation for lead pipe is as suction
pipes in wells.  Here the corrosion is often very rapid, and it is
rendered more violent by the fact that  the continual changes of
level expose a longer or shorter portion of the pipe  to the alter-
nate  action of air  and water. There are  instances enough of
lead poisoning from this cause.
   It may be remarked, in this  connection, that the lead  pipe
now in use, at least in the eastern part of the country, is much
inferior in strength and durability, and apparently more readily
corroded than that formerly in use.  The lead now in  the  mar-
ket has been desilverized by the zinc process, and this seems to
give it a particular and disadvantageous character.
   Other  materials besides lead are used  in the house service.
To block tin or to tin-lined lead pipes,  if  the latter are properly
made and properly put together, there is no objection on  sani-
tary grounds.  The corrosion of the tin by ordinary waters would
result in the formation of insoluble and harmless substances. As
to the suitability of the brass pipes which have been proposed,
there  seems to be no exact information.   To the various sorts
of " enameled"  wrought-iron pipes which are  in  the market
there  is no sanitary objection.  The coating or enamel  is gener-
ally some preparation of coal tar,  with or without linseed oil, and
this sort of pipe is particularly adapted for  use in wells, where a
portion of the outer surface is exposed alternately to the action
of air and water; unfortunately, the coating is  not always per-
fect, and when the original surface of the pipe is exposed, rusting
begins.  Zinced or " galvanized " iron, as it is called, is fully as bad
in respect to rusting.  The pipes are prepared by dipping  the
iron, previously well cleaned by means of dilute acid, into a  bath
of melted zinc.  The zinc adheres firmly to the surface of  the
iron, and penetrates it to a certain extent, so that we do not deal
with a simple  coating, such as we have on tinned iron, or on the
various forms  of enameled pipe.  The idea is that the zinc  shall
protect the  iron by  virtue  of a galvanic  action between  the
two metals, and it does protect the iron for a time.   When the
pipes are  exposed  to  the action  of water, corrosion begins at
once : at first, the action is on the zinc alone, provided the origi- 
SERVICE PIPES.
215
nal iron was  free from  rust, and  the treatment with zinc was
thorough;  but after a time the zinc which  remains will cease to
protect the iron, and iron rust will begin to form.  As regards
this  action, it is simply a question of time.   Water that has
passed through zinced pipes will be found almost always, if not
invariably,  to  contain zinc compounds, either in solution or in
suspension ; the amount, however, is  generally very small. As
to the effect of such water on health,  there is some difference of
opinion, but it is generally believed that the pipes may be safely
used.*
   One of  the best materials  for  service pipes is  wrought iron
protected by the Bower-Barff process, provided practical experi-
ence justifies the theoretical expectations. To such pipes, coupled
without the use of red or white lead, there can be nothing supe-
rior from a sanitary  point of view, and for  use in wells and cis-
terns they will supply a very serious want.  Ordinary wrought-
iron pipes,  although possessing many advantages, have the great
disadvantage  of rusting very readily : the iron rust  is harmless
but unsightly in drinking water, and may render the water unfit
for culinary purposes and for use in the laundry.

   * For a full discussion of this subject, see Dr. Boardman's paper in the Report oi
the Mass. State Board of Health for 1874. 
BIBLIOGRAPHY.
   THE following list of books makes no claim to being exhaustive.  It includes
most of the  works referred to in the  preceding pages, and may perhaps be
described as a list of such works as would together make a fair nucleus for a
library of water supply, other than from a  strictly engineering  standpoint.
Papers in periodical publications are not included.

   I.—Works of a General Character, mainly from an Engineering
                              Point of View.

   Fanning,  J. T. : A  Practical  Treatise on  Water-Supply Engineering, etc.
8vo, pp. 650. Van Nostrand, New York, 1877.
   Grahn, E. : Die stadtische Wasserversorgung.   3 vols. 8vo. Vol. I.  Mi'in-
chen, 1877.   [Contains Statistik der stadtischen Wasserversorgung: Beschrei-
bung der Anlagen in Bau und Betrieb.]
   Humber,  William :  A Comprehensive Treatise on the Water Supply ot
Cities and Towns, etc.  Folio, pp. 378, and many plates.   London, Crosby,
Lockwood & Co., 1877.  [An American edition was published  by Geo. H.
Frost, Chicago.]

   II.—Works  of a General Character,  mainly from a Chemical or
                       Sanitary Point of View.

   Buck : Hygiene and Public Health.  2 vols. 8vo.  New York, Wm. Wood
& Co.,  1879.
   Denton, J. Bailey : Sanitary Engineering.  8vo,  pp. 429, with many plates.
Spon, London, 1877.
   Fischer :  Die  chemische  Technologie des Wassers.  8vo.  Braunschweig,
1878-80.
   Fodor : Boden und Wasser.  Braunschweig, 1882.
   Great Britain : Report of the Royal Commission  on Water-Supply, with
Minutes of Evidence.  Parliamentary Documents.  4to.  London,  1869-70.
   Great Britain :  Sixth Report of the Commissioners appointed in 1868 to in-
quire into the Best Means of Preventing the  Pollution of Rivers.  Domestic
Water Supply of Great Britain.  4to.   London, 1876.
   [This report contains, besides complete statistics of  the water supply of
Great Britain, considerations and  accounts  of experiments on the  following
topics :
   On the alleged self-purification of polluted  rivers.
   On the propagation of epidemics by potable water. 
BIBLIOGRAPHY.
217
   On the alleged influence of the hardness of water upon health.
   On the superiority of soft over hard water in cooking.
   On the softening of hard water.
   On the improvement of potable water by filtration.
   On the deterioration of potable water by transmission  through  mains and
service pipes.
   On the constant and intermittent systems of water supply.]
   Lefort, Jules : Traite" de Chimie  Hydrologique.  8vo, pp.  798.  Deuxieme
edition.  Paris, 1873.
   Lersch, Dr. B. M. :  Hydrochemie oder Handbuch  der Chemie  der natiir-
lichen Wasser, 2   Auflage.  8vo, pp. 718.   Bonn, 1870.
   Parkes, E. A., M.D.:  Manual of Practical  Hygiene.   Fifth edition.  8vo.
London and Philadelphia, 1878.
   Reichardt: Grundlagen zur Beurtheilung des Trinkwassers.  3te  Auflage.
8vo, pp. 107.  Jena,  1875.
   Sander, Dr.  Friedrich :   Handbuch  der  offentlichen Gesundheitspflege.
8vo, pp.  503.  Leipzig, 1877.
   Wolffhi'igel :  Wasserversorgung.  [Aus dem  Handbuch der  Hygiene und
der  Gewerbekrankheiten, von Pettenkofer  und  Ziemssen. ]   8vo,  pp.  244.
Leipzig,  1882.

                 III.—On the Pollution  of Streams.

   Great Britain : Rivers Pollution Commission, appointed in  1865.  Three
Reports.   Parliamentary Documents.  4to.   London, 1866-67.
   Great Britain : Rivers Pollution Commission, appointed in 1868.   Six Re-
ports.   Parliamentary Documents.  4to.  London, 1870-74.
   Massachusetts: Seventh Annual  Report of the State Board  of Health,
containing a special  report on  the  pollution  of streams, etc.   8vo.   Boston,
1876.
   Paris  : Assainissement de la Seine.   Epuration et Utilisation des Eaux
d'Egout.  Documents administratifs ; Enquete ; Annexes.  3 vols. 8vo, with
plates.   Paris, 1876.

          IV.—On Filtration, Ground Water,  Wells,  etc.

   Belgrand,  M. : Les Travaux souterrains de Paris.   Etudes pre"liminaires.
La Seine.  Regime de la Pluie, des Sources,  des Eaux courantes.   Applica-
tions a PAgriculture.  8vo, pp. 612, with atlas.   Paris, Dunod, 1875.   [Espe-
cially chap, vii,  Des nappes d'eau souterrains, and chap, xxvi, Du filtrage
des eaux, etc.]
   Berlin :  Vorarbeiten  zu einer zukiinftigen  Wasserversorgung der  Stadt
Berlin.   Ausgefuhrt  in  den  Jahren 1868 und 1869  von L.  A. Veitmeyer.
Svo,  pp. 368, with atlas.  Berlin,  Reimer, 1871.  [Especially pp. 109-130—
experiments on the ground water in the neighborhood of the Tegeler See.]
   Berlin :  Reinigung und Entwasserung Berlins.   Berichte iiber  mehrere
auf Veranlassungdes Magistrats der ktfnigl. Haupt-und Residenzstadt Berlin
Versuche und Untersuchungen.   12 Hefte, with 3 Anhange.   8vo.   Berlin, 
218
WATER SUPPLY.
Hirschwald, 1870-76.  [Especially Heft v,  "iiber die  Grundwasserverhalt-
nisse," with a great number of profiles.]
   Brooklyn, N. Y.  : The Brooklyn  Water Works  and Sewers.   Prepared
and  printed by  order of the Board of Water Commissioners.   4to, pp.  159,
with 59 lith. plates.  New York, Van  Nostrand, 1867.
   Darcy, Henry :  Les fontaines publiques de la ville de Dijon.   4to, pp.  647,
with atlas.   [Especially Appendix D, Filtrage.]
   Dresden : Das Wasserwerk der Stadt Dresden erbaut in den Jahren 1871-
1874, von B. Salbach.  8vo.  In three parts,  with atlases containing many
plates.  Halle, Knapp, 1874-76.
   Dupasquier, A. :  Des Eaux  de Source et des Eaux de Riviere comparees,
etc.   i2mo, pp. 414.   Paris et Lyon, 1840.
   Dupuit, J. :  Traite de la  Conduite  et de la Distribution  des Eaux,  etc.
Suivi de la Description des Filtres naturelles de  Toulouse par D'Aubisson.
4to, with atlas.   Paris, 1854.
   Fischer, Dr. F. :  Das  Trinkwasser, seine Beschaffenheit,  Untersuchung
und Reinigung unter Beriicksichtigung der Brunnenwasser Hannover.   8vo,
pp. 63.  Hannover, 1873.
   Gottisheim: Das  unterirdische Basel.   8vo,  pp.  72.   Basel, 1868.  [2d
Edition, 1873.]
   Grahn  and Meyer :  Reisebericht einer von Hamburg nach Paris  und Lon-
don  ausgesandten  Commission   iiber  kiinstliche  centrale Sandfiltration  zur
Wasserversorgung von Stadten, und  iiber Filtration in kleinen Massstabe.
Von  E. Grahn und F. Andreas  Meyer. 8vo, pp.  153.  Hamburg,  Meissner,
1877.  [Especially Anlage 3, " Historische Notizen iiber kiinstliche Filtration
im kleineren Massstabe."]
   Grimaud, de C  ux : Des Eaux publiques, etc.  8vo, pp. 348.   Paris, Dezo-
bry,  1863.  [Especially chap, xiv, " de la clarification des eaux publiques."]
   Halle: Das Wasserwerk  der Stadt Halle, erbaut  in den Jahren 1867  und
1868.  Von B. Salbach.  Folio,  with atlas.  Halle, Knapp, 1871.
   Kirkwood, J. P. :  Report on  the Filtration of River Waters for the Supply
of Cities, as  practised  in  Europe.   4to, pp. 178, with 30 plates.  New York,
Van  Nostrand, 1869.
   Munich :  Berichte iiber die Verhandlungen und die Arbeiten der Commis-
sion  fur Wasserversorgung,  Canalisation, und Abfuhr.  Erster Bericht, 1874-
75 ;  Zweiter Bericht,  1876, und Anhange, 1877.  4to, with plans and profiles.
Munchen, Miihlthaler, 1876, 1877.
   Nichols, W. R. : On the Filtration  of Potable Water.  Reprinted from the
Ninth Annual  Report of the Mass. State Board of Health.  8vo, pp.  93. New
York, Van Nostrand, 1879
   Pieike : Mittheilungen iiber natiirliche und kiinstliche Sandfiltration, nach
Betriebsresultaten der Berliner Wasserwerke vor  dem  Stralauer Thor.   8vo,
pp. 75.  Berlin, 1881.
   Schorer, Th.:  Liibeck's Trinkwasser, 8vo, pp.  284.  Liibeck, Seelig, 1877.
[Especially pp. 248-257, describing  the deterioration of water  by vegetable
growth and decay, etc.] 
                           BIBLIOGRAPHY.                        219

   Spon, Ernest:  The present Practice of Sinking and Boring Wells.  i2mo,
pp. 216.   London, Spon, 1875.
   Ward, F. O.:  Moyens de cre"er des sources artificielles d'eau pure pour
Bruxelles.  8vo, pp. 106.  Bruxelles, Decq, 1853.
   Wiebel, Dr. F,:  Die Fluss- und  Bodenwasser  Hamburgs.   Chemische
Beitrage zur Analyse gewohnlicher  Lauf- Nutz-  und Trinkwasser  sowie zu
der Frage der Wasserversorgung grosser Stiidte von sanitaren und gewerb-
lichem Standpunkte,  4to, pp, 152.   Hamburg,  Meissner,  1876.
   Wolff": Der Untergrund und  das  Trinkwasser der Stadte.  2te  Auflage.
8vo, pp.  60.   Erfurt,  1873.

            V.—On the Sanitary Examination of Water.

   Eyferth, B. :  Die mikroscopischen Siisswasserbewohner  in  gedrangter
Uebersicht. 8vo, pp. 60.  Braunschweig, 1877.
   Fox, Cornelius B., M.D. :  Sanitary Examination of Water, Air and Food.
8vo, pp. 508.   London, 1878.
   Frankland, Dr. E.: Water Analysis for Sanitary Purposes.  i2mo, pp. 139.
London,  Van Voorst, 1880.
   Hassall : Microscopical Examination of Water Supplied to the Inhabitants
of London, etc.  London, 1851.
   Kubel, Dr.  Wilhelm:  Anleitung  zur Untersuchung von Wasser, u. s. w.
8vo, pp. 184.   Zweite Auflage von Dr. Ferd. Tiemann.  Braunschweig, 1874.
   Macdonald, J.  D., M.D.: A  Guide to the Microscopical Examination of
Drinking Water.  8vo, pp. 65 and 24 plates.  London and Philadelphia, 1875.
   Neuville: Des Eaux de Paris.  Essai d'Analyse micrographique compare'e.
4to, pp. 63.  15 plates.  Paris,  1880.
   Schutzenberger:  On  Fermentations.  i2mo, pp. 331.  Intern.  Sci. Series.
New York, 1876.  [This contains a description of  Schiitzenberger's method of
determining dissolved oxygen, pp. 108 and foil.]
   Wanklyn, J. A.: Water Analysis: a Practical Treatise on the Examination
of Potable Water.   By J. A.  W. and E. T. Chapman.  l2mo, pp. 182.  Fifth
edition, re-written by J. A. Wanklyn. London, 1879.

                         VI.—Miscellaneous.

   Boston, Mass.; Report of Cochituate Water Board, 1874.  [Contains a re-
print of a report by Geo. F. Deacon, Borough  Engineer,  Liverpool,  Eng., on
the subject of " Waste."]
   Boston, Mass.:  Report on Waste of Water (May 25, 1882).  Boston City
Document No. 78,  1882.
   Bowditch:  Public Hygiene in America.  8vo.   Boston, 1877.
   Deacon: The Constant Supply and Waste of Water. A paper read before
the Society of Arts, May 19, 1882.  4to, London, 1882.
   Magnin: The Bacteria, translated by Dr.  Geo. H.  Sternberg,  U.  S. A.
8vo, pp. 227.   Boston, 1880.
   Nageli: Die niederen Pilze.  Miinchen, 1877. 
220                      WATER SUPPLY.

   Nageli:  Untersuchungen iiber  niedere  Pilze.   8vo,  pp.  285.  Miin'.'hen
und Leipzig, 1882.  [This contains Buchner's paper referred to on page 21. J
   De Ranee: The Water Supply of England and Wales.  8vo, pp. 623.   Lon-
don, 1882.
   Kuessner und Pott:  Die  acuten Infectionskrankheiten.   8vo,  pp.  460.
Braunschweig, 1882.
   Parry: Water, its Composition, Collection,  and Distribution.  i2mo, pp.
184.  London, 1881.
   Rowan: Boiler Incrustation  and Corrosion.   l8mo, pp. 48.  New  York,
Van Nostrand, 1876.
   Wilson: Treatise on Steam Boilers.  Third edition.  i2mo, pp. 328.   Lon-
don, 1875. 
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O 4-. COld vj tO O M in    4i. COld M  K O^HUi    4i.  COld vl  to  O H 1
4^  COld  vl tO O M
4^  Cold vi to CT* m
4^  COld vl to CN M 
222
WATER SUPPLY.
TABLE  XXXII.—.
For the Conversion of Degrees of the Centigrade Thermometer into
       Degrees of Fahrenheit's Scale.
Cent.	Fahr.	Cent.	Fahr.	Cent.	Fahr.	Cent.	Fahr.
0	320	26	78.8	51	123.8	76	168.8
I	33-8	27	80.6	52	125.6	77	170.6
2	356	28	82.4	53	127.4	78	172.4
3	37-4	29	84.2	54	129.2	79	174.2
4	39-2	30	86.O	55	I3I-0	80	176.0
5	41.0	31	87.8	5ft	132.8	81	177-8
6	42.8	32	89.6	57	134.6	82	179.6
7	44.6	33	9I.4	58	136.4	83	181.4
8	46.4	34	93-2	59	138.2	84	183.2
9	48.2	35	95o	60	I40.O	85	185.O
10	50.0	36	96.8	61	141.8	86	186.8
n	51.8	37	98.6	62	143.6	87	188.6
12	53-6	38	100.4	63	145-4	88	190.4
13	55-4	39	102.2	64	147.2	89	I92.2
14	57-2	40	104.0	65	149.0	90	194.O
15	59.0	41	105.8	66	150.8	9i	195.8
16	608	42	107.6	67	152.6	92	197.6
17	62.6	43	109.4	68	154-4	93	199.4
18	64.4	44	111.2	69	156.2	94	201.2
19	66.2	45	1130	70	158.0	95	203 0
20	68.0	46	114.8	7i	159.8	96	204.8
21	69.8	47	116.6	72	161.6	97	206.6
22	71.6	48	118.4	73	163.4	98	208.4
23	73-4	49	120.2	74	165.2	99	210.2
24	75-2	50	122.0	75	167.0	100	212.0
25	77.0						
Metric System  of Weights and Measures.

                  Weights.
I Milligram  mgm.
1 Centigram
1 Decigram
1 Gram      grm.
= 0.001 gram.
= 0.01    "
= 0.1     "
= 1.0     "
I Gram
1 Dekagram
r Hectogram
1 Kilogram    kilo
grm.  =
      1 gram.
=   10 grams.
=  100   "
= 1000   "
1 Millimeter  m.m.
I Centimeter  cm.
1 Decimeter  d.m.
1 Meter        m.
Measures of Length.
= 0.001  meter.
= 0.01     "
= 0.1      "
= 1.0      "
1 Meter
I Dekameter
1 Hectometer
1 Kilometer kilom.
=    1 meter.
=   10 meters.
=  100   "
= 1000   "
Measures of Volume.
1 Cubic Centimeter    c.c. or c.m.!
1 Cubic Decimeter            dm.'
1 Cubic Meter                ~^T'
=    0.001 liter.
=    1.000   "
= 1000.000   " 
TABLE XXXIII.—Equivalents of Various Measures of Volume.*
	Its Equivalent in						
Name of Measure.	U. S. Gallons.	Imperial Gallons.	Liters.	Cubic Feet.	Cubic Meters.	Cubic Inches.	Pounds avoirdupois (of water).
	I. 1.20032 O.2641866 7.480152 264.18657	O.833111 I. O.220097 6.232102 220.096714	3.785203 4-543457 I. 28.315289 1,000.	0.133681 O 160459 O.035317 I. 35.316609	O.OO37852 0.0045434 O.OOI 0.028315 I.	231. 277.274 61.0271 1,728. 61,027.0963 I.	8.3388822f
							
							2.204737 62.37916 2,204.737 O.036099
							
i Cubic Meter...........							
							
							
    * This Table is taken from Kirkwood's Filtration of River Waters, p.  167.
    f The exact number of  pounds or of grains in  a gallon is differently given by different authorities, the discrepancies arising from  a
difference in the value assigned as the weight of a cubic inch of water.   The weight of a cubic inch of water is usually stated to be, according
to the English standard, 252.458 grains, at 620 F. and under 30 inches barometric pressure.  The English imperial gallon contains 277.274
cubic inches of water, the weight of which is taken to be 10 pounds avoirdupois or 70,000 grains.   The  old wine gallon of 231 cubic inches,
according to this standard, would contain 58,318 grains, but some authorities give the amount as 58,333.3.   The United States standard gal-
lon of 231 cubic inches, contains, at 390  83 F. (the temperature of the maximum density of water adopted by Hassler), and under a barometric
pressure of 30 inches, 58,372.175 grains of pure water : this fixes the weight of a cubic inch of water, at that temperature, as 252 6933 grains.
CENTIMETERS.
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TABLES FOR CALCULATION.
225
TABLE XXXV.—For the  Conversion of Parts per 100,000 into Grains per Gallon,
            and vice versa  : also, for Comparing Degrees of Hardness.
			Degrees of Hardness.		
	Grains in	Grains in		English : Grains CaC03 in	
Parts in 100,000.	U. S. Standard	Imperial	French:		German :
	Gallon.	Gallon.	Parts CaCOa		Parts CaO
			in 100,000.	imp. Gallon.	in ico,ooo.
I	0.5837	0.7	I	0.7	0.6
2	I.1674	1.4	2	1.4	I.I
3	I-75I2	2.1	3	2.1	i-7
4	2-3349	2.9	4	2.8	2.2
5	2.9186	3-5	5	3-5	2.8
6	3-5023	4.2	6	4.2	3-4
7	4.0861	4.9	7	4-9	3-9
8	4.6698	5-6	8	5-6	4-5
9	5-2535	6-3	9	6-3	5-o
I-7I3I	1	1.1992	i-4	1	0.8
3.4262	2	2-3983	2.9	2	1.6
5-1393	3	3-5975	4-3	3	2.4
6.8524	4	4.7967	6-7	4	3-2
8.5655	5	5-9958	7-1	5	4.0
10.2786	6	7-I950	8.6	6	4.8
11.9917	7	8•3942	10.0	7	5-6
13.7048	8	9-5934	11.4	8	6.4
15.4179	9	10.7925	12.8	9	7-2
1.4286	0.8339	1	1.8	1.2	1
2.8571	1.6678	2	3-6	2-5	2
4-2857	2.5017	3	5-4	3-8	3
5-7143	3-3356	4	7-i	5 0	4
7.1428	4-1695	5	9.0	6-3	5
8.5714	5-0033	6	10.7	7-5	6
10.0000	5-8372	7	12.6	8.8	7
11.4286	6.6711	8	14-3	10.0	8
12.8571	7-5050	9	16.1	"•3	_?____\
15 
 
INDEX.
 Aberdeen, corrosion of pipes in, 208.
 Absorption of gases, 11.
 Aeration, 150.
 Africa, artesian wells in, 134.
 Air, composition of, 12.
 Aire and Calder rivers, pollution of, 58.
 Alabama, artesian wells in, 135.
 Albuminoid ammonia, 39.
 Algae at Berlin, 157.
      in deep-seated water, 143.
      in water supplies, 86.
      spores not removed by sand filtra-
        tion,  165.
 Algeria, artesian wells in,  135.
 Altenburg,  consumption of water in, 194.
            water supply of, 207.
 Alton, 111., filters at, 168.
 Altona, consumption of water in,  194.
        filtration at, 156.
        use of Barff's process in, 209.
 Alum, treatment of water with, 187.
 Ammonia, coefficient of absorption of, 11.
           determination of, 37.
 Ammonia  method of water  analysis,  37,
  38.
 Amsterdam, water supply, 121.
 Anabaena circinalis,  87, 88.
 Analyses, methods of reporting, 8, 30.
 Analysis, methods of, 29.
 Animal life, 79.
 Anthrax, 20.
 Aquamalarial  fever,  52, 100.
 Artesian wells at Grenelle, Paris, 137.
                 St. Louis,  137.
                 Charleston, S. C, 135.
               in Alabama, 135.
                 Algeria, 134.
                 China, 134.
               examination   of (Table),
                 144.
               pollution of, 143.
               uncertainty of, 137.
Artificial ice,  53.
Atkins's cistern filters,  178.

Bacillus,  -li, 20.
           anthracis, 20.
           subtilis, 21.
Bacteria, 19, 45, 67.
         removed by spongy iron, 173.
 Baird's system of distillation, 190.
 Baltimore, Md.,  water supply, 204.
 Bamberg, consumption of water in, 194.
 Bangor, Me., filters at, 169.
 Barff's process, 209, 215.
 Belgium, pollution  of streams in, 72.
 Belgrand, quoted, 120.
 Bell's waste detector, 201.
 Berlin,  experience with meters, 204.
        filtration at, 157.
        ground water measurement at,  110.
        water supply, trouble in,  125.
 Bibliography, 216.
 Biological examination of water, 45.
 Birmingham,  consumption  of water in.
   194.
 Bischof's experiments on bacteria, 173.
         spongy iron for niters, 166,  327.
 Blackburn,  Eng., consumption of  water
  in, 194.
 Blackstone River, pollution of, 59, 62.
 Bohemia, spring and well waters  in, 145.
 Boiler scale, 181.
 Bone coal for filters, 170, 334, 336.
 Bonn, consumption of water in, 194.
 Boston, consumption of water in, 195.
        corrosion of iron pipes in, 209.
        lead pipes in, 213.
        waste water inspection, 201.
        water,  examination of, 101, 104.
 Bower-Barff process.   See Barff.
 Brackett, Dexter, quoted,  194, 195, 200,
  201, 205.
 Bradford Beck, pollution of,  58.
 Braunschweig,  consumption  of water in,
  194.
 Breslau, experience with meters, 204.
 Brewer, Dr., quoted,  52.
 Brick for filters, 168, 332.
 Brooklyn, daily consumption in, 195.
          inspection of plumbers' fittings,
             205.
          water supply of, 105.
          well in Prospect Park,  in.
 Buchanan, quoted,  15.
 Buchner's experiments  on Bacillus  an-
  thracis, 21.

Cambridge, Mass., consumption of water
  in, 195. 
228
INDEX.
Carbide of iron for filters, 166.
Carbonate of lime, solubility of, 9.
Carbonic  acid, coefficient  of  absorption,
                  11.
               solution of,  12.
               in natural waters. 31.
Cast-iron pipes, corrosion of, 207.
               method of coupling, 209.
Cellulose used for filters, 180.
Chandler, analysis of Croton water, 8.
Charbon,  20.
Charleston,  S. C,  artesian wells at, 135.
Chemical  analysis, value of,  44.
          solution, 2.
          treatment of water, 187.
             with alum, 187.
             with  lime, 183, 188.
             with perchloride of iron, 187.
             with  permanganate  of pot-
               ash, 188.
Chicago, consumption of water in, 195.
         River, pollution of, 59.
China, artesian wells in, 134.
Chlorides, significance of, 33, 68.
Chlorine,  a  means of tracing pollution,
            131-
          in natural waters,  33.
          estimation of, 33.
Cholera and drinking water, 22.
Church's waste indicator, 379.
Cincinnati, consumption of water in, 195.
          detection of waste,  201.
Cistern filters, 176.
       water, examination of, 50.
                             (Table), 51.
Cisterns, sediment in, 50.
Clark's process, 183.
Classification of waters, 17,  42, 43.
Clathrocystis aeruginosa, 88.
Clinton, Iowa, filters at, 168.
Clyde, pollution of, 59.
Coelosphoerium, 87.
Cologne (Coin), consumption of water in,
  194.
Color, method for estimating,  149.
Conduits, 206.
          growth of sponge  in, 207.
          various,  length of, 207.
Consumption of water in American cities,
                           195.
                        European cities,
                           194.
Corroded  pipes, diminished  flow through,
  207.
Corrosion of cast-iron pipes, 207.
Couste, quoted, 5.
Crenothrix Kuhniana, 126, 210.
Crookes, Prof., quoted, 188.
Croton water, action on lead, 213.
              analysis of, 8.
Cucumber taste, 91.
Cyclops quadricornis, 70.
Danube,  suspended matter in, 57.
Danzig, water supply of, 207.
Daphnia pulex, 79.
Davis, J.  P., cost of sand filtration,  165.
Deacon's system in Liverpool, 199.
                   Glasgow, 200.
                  Boston, 201.
Deacon's wastewater meter, 196-199.
Deep-seated water, algae in, 143.
                   as a source of supply,
                      J33-I45-
                   characteristics of, 142.
                   examination of, 142.
                   (Tables), 144, 145.
                   pollution of, 143.
Deep sea thermometer, 95.
Deep wells, 134, 139.
           examination of (Table), 144.
Degrees of hardness, 34.
           different  thermometers  com-
             pared, 221, 222.
Deposition as means of self-purification,
  67.
De Ranee, quoted, 137, 141.
Desmids,  86.
Detroit, consumption of water in, 195.
        wooden pipes in, 211.
Diatoms, 86.
Dilution as means of natural purification,
             68.
           a guaranty of safety,  71.
Discharge from corroded pipes, 208.
Disease and drinking water, 17-28.
Dissolved solids, effect of, 10.
                estimation of, 32.
Distillation, 189.
            Baird's system, 190.
            Normandy's system, 192.
Distribution pipes, 206.
Double supply, 206.
Dresden, consumption of water in, 194.
         ground water measurements, 110.
         water supply of, 108, 120.
Drinking water and disease, 17-28.
               best, 133.
               theory,  22.
Drinking, water most suitable for, 27.
Driven wells, 109, 112-117.
             principle of, 114.
Dublin, consumption of water in, 194.
Dubuque, Iowa, water supply of, 138.
Durance, suspended matter in, 57.

Edinburgh, consumption of water in, 194.
Elbe filtered at Altona, 156.
     pollution of, 71.
Emmerich, Dr., quoted, 24, 26, 45.
England,  pollution of streams in, 73.

Fall River, Mass., consumption of  water
                     in, 195.
                    use of meters in, 203. 
INDEX.
229
Ferrous sulphate test, 35.
Filter, Piefke's, 180.
       the multifold, 179.
Filter basin at  Waltham, Mass.,  119.
Filter beds, advantage of covering, 163.
            construction of, 151, 155.
            frequency of cleaning, 157.
            method of cleaning,  152.
Filter gallery at Columbus, O., 108.
                Halle, 108.
                Lowell, 107.
                Taunton,  108.
Filters, household, bone coal for, 170, 172.
                  for cisterns, 176-178.
                  requirements of, 170.
                  reversible,  171.
                  silicated carbon for, 172.
                  simple form of,  174.
                  spongy  iron for, 173.
                  wood charcoal for, 174.
Filter press, Porter's, 185.
Filtration, 151.
          at Alton, 111., 168.
             Altona, 156.
             Antwerp, 166.
             Bangor, Me., 169.
             Berlin, 157, 158, 160, 164.
             Clinton, Iowa, 168.
             Hudson, N. Y., 161, 163.
             London, 159, 160.
             Magdeburg,  164.
             Malone, N. Y.,  168.
             Marshalltown, Iowa, 168.
             Poughkeepsie, N. Y , 162.
             Wakefield, Eng., 166.
             Zurich, 157.
          extent of,  151.
           expense of, 165.
           for manufactories,  179.
          household, 169.
                     materials used, 169.
          in winter, 164.
           natural, 106,  117.
          principles of, 152.
          rate of, 152, 156, 158.
       (See also Filters, household.)
Flint,  Dr. Austin, quoted, 23.
Flushing, water supply of, 193.
Forel, Dr.,  quoted, 80.
Fox, Dr.  C. B., quoted, 44.
France, pollution of streams in,  59, 73.
Frankfort, consumption of water in, 194.
          temperature of water, 207.
          water supply, 207.
Frankland,  Dr., quoted, 35, 40,  4*-
Frankland's classification of water, 41.
            method of analysis,  37, 39.
            report on Antwerp filters, 166.

Galvanized iron,  corrosion of, 214.
Ganges,  suspended matter in, 57.
Gases, coefficient of absorption,  11.
Gases in natural  waters, 31.
      solution of, 10.
      supersaturated solutions of, 12.
Germ theory, 18.
Germany, pollution of streams in, 59.
Glasgow,  consumption of water in,  .94.
          inspection of fittings in, 205.
          lead pipe in, 213.
          water supply of,  207.
          waste water detection, 200.
Glasgow water, examination of,  101.
Gold, solubility of, 15.
Gotha, water supply of, 207.
Grahn, quoted, 151.
Great Britain, pollution of  streams in, 58,
  73-
Greaves, Mr. Chas., on filter sand, 155.
Crenelle,  Paris, artesian well at, 137.
Ground water  as source of  supply, 105,
                  132-
               defined,  105.
               effect of pumping on, 109-
                  112.
               examination of,  122.
                          (Table), 124.
               hardness of, 120.
               inclination  of, 105.
               temperature of, 118.
               utilization  of, 106,  109.
Ground-water supplies, difficulties of, 123,
                        128.
                      at Berlin, 125-127.
                        Halle, 127.
                        Leipzig, 123.
                        Lille,  127.

Halle,  water  supply of, 108.
              trouble  with, 127.
Hamburg, consumption of water in, 194.
Hannover, consumption of water in, 194.
Hardness, degrees of,  34.
           determination of, 33.
           permanent, 33, 186.
           temporary, 34,  181.
Hard water,  17, 181.
            softening  of, 181-187.
            wholesomeness of, 18.
Hatton, experiments on  spongy  iron, 173.
Head, term defined, 156.
Heisch's test, 46.
Hoadley, J. C, quoted, 116.
Hooghly, character of water, 16.
Household filtration (See Filtration).
Hudson, N. Y., filtration at, 161,  163.
Hull, Eng., consumption of water at, 194.
Humus,  84.
Hunt, T. Sterry, quoted, 16.

Ice, chemical examination of, 54,  55.
     impure, 52.
     in filtered water,  179.
     natural and artificial, 52. 
3EX.
23O                                INI


Impounding reservoirs, 85.
Improvement of natural water, 146.
             by aeration, 150.
             chemical processes, 187.
             Clark's process, 181.
             distillation, 189.
             filtration,  151.
             sedimentation, 147,
             softening, 181.
             storage, 149.
Infusoria, 83.
Iron, carbide of, 166.
     compounds of, in ground water, 123,
       125, 129.
     perchloride of, 187.
     pipes, corrosion of, 207.
           protection of, 208.
           sediment in, 210.
     spongy, 166.
Irrawaddy, suspended matter in, 57.
Irwell, pollution of, 58.

Jamieson, M. B., quoted, 207.

Karlsruhe, consumption of  water in,
  194.
Kassel, consumption of water in, 194.
Kerner, quoted, 207.
Kirkwood, quoted, 155, 164.
Koch,  quoted, 20.
Koch's biological method, 46.

Latham, quoted, 92,  141, 143.
Latham's apparatus for  tempering water,
  93-
Lawrence, Mass.,  manufacturing indus-
  tries at, 63.
Laws against pollution of water supplies,
  71-78.
Lead pipes, action of  water on, 211-214.
Lead poisoning, 213.
Leeds, Eng.,  consumption  of water in,
  194.
Leipzig, consumption of water in, 194.
        water supply of, 123.
Leyden,  water supply of, 121.
Lille, trouble with water  supply, 127.
Lime,  water treated with, 183, 188.
Liverpool, Eng., consumption of water in,
             194.
          inspection of fittings in, 205.
           softening of water at, 185.
          water supply, 138.
London,  results of filtration at, 159, 160.
         temperature of  water supplies,
           93-
         water, examination  of, 102.
         water supply, 102, 138.
         wells in and near, 137.
Long Island, N. Y., ground water on,  105,
  ill, 121.
Loss on ignition, 37.
Lowell, Mass., consumption  of  water in,
                 195.
               filtering gallery at.  107.
               manufacturing refuse at,
                 63-

Maas, suspended matter in,  57.
Magdeburg, experience with meters, 204.
            filter beds at, 164.
Manchester, Eng., consumption of water
                    in, 194.
                  inspection of  fittings
                    in, 205.
                  lead pipe  in,  213.
Mallet, Prof., quoted, 24, 25, 35, 40,  42.
Malone, N. Y., filters at, 168.
Marshalltown, Iowa, filters at, 168.
Memphis, cisterns in, 50.
Merrimack river, pollution of, 62, 63.
Meters for checking waste, 203.
        German experience with, 204.
Microbes, 19.
Micrococcus, -ci, 20.
Microzymes, 19.
Milzbrand, 20.
Mississippi filtered at Alton,  168.
           sediment in, 16, 57.
Mixed solutions, condition of, 7.
Mountain fever, 52, 100.
Multifold filter,  179.
Munich, water supply of, 207.

Natural filtration, 106, 117.
Nageli, quoted, 19.
Nessler test, delicacy of, 34.
New Orleans, cisterns in, 49.
              wells in,  130.
New River water, filtered, 160.
New York,  inspection of fittings, 205.
            lead pipes in, 213.
            water supply, 194, 207.
            wells in, 138.
Nitrites and nitrates, 35.
        significance of, 36.
Nitrogen, coefficient of absorption, II.
          (combined) in water, 34.
          in natural waters,  31.
          organic, 34.
Nodularia, 89.
Normandy's system of distillation, 192.
Nostocs, 87.

Odors and tastes of surf ace waters, 80, 84,
  85, 90.
Ohio  River, pollution of, 70.
Organic and volatile matter,  37.
Organic c-rbon, 40.
        matter, 24, 36, 38.
        nitrogen, 34.
Oxidation, a means of purification, 66.
Oxygen, coefficient of absorption,  11.
         in natural waters, 31. 
IND
Paris, consumption of water in, 194.
       water supply of, 207.
Passaic River, pollution of, 59, 170.
Pawtucket, R. I., use of meters in, 203.
Permanganate method of analysis, 37.
               of  potash,  a   purifying
                            agent, 188.
                          in analysis, 37.
Philadelphia, consumption  of water  in,
   195-
Physical solution, 1.
Piefkc, quoted, 157,  161.
Piefke's filter, 180.
Pipes, brass, 214.
       enamdei, 214.
       galvanized iron, 214.
       iron (See Iron pipes).
       lead,  211.
       service, 211.
       tin-lined lead, 214.
       wooden, 211.
       wrought iron, 210.
Plants, aquatic, 83.
Polluting liquids defined,  74.
Pollution of streams, 57, 78.
                    prevention of, 71-78.
          of wells, 128.
Popular tests, 46.
Porter-Clark process, 184.
Po, suspended matter in, 57.
Potamogeton, 83.
Potash, permanganate of,  37, 188.
Poughkeepsie, alga; at, 90.
               filtration at, 161, 162.
Previous sewage contamination,  35.
Protection of iron pipes, 208.
Providence, consumption of water in, 195.
            inspection of fittings, 205.
            use of meters  in,  203.
Prussia, pollution of streams in,  72.
Purification of water by freezing, 53.
         (See also Improvement.)

Quantity and waste, 194, 206.
           necessary  for  public supply,
              194.

Rain water, analyses of. 48.
             as source of  supply, 48-55.
             requires filtration,  175.
             storage of, 49.
Remsen's investigations at Boston, 80, 91.
Rhine,  suspended matter in, 57.
Rhone, suspended matter in,  57.
River Lea water filtered,  159, 160.
Rivers Pollution Commission, quoted, 41,
  48, 66, 74,  102, 103, 144, 145, 159. 160,
  166.
Rivers Pollution Prevention act (1876), 74.

Salbach's photometer, 148.
Samples, collection of, 47.
•EX.                                23I


 Sand filtration, 151.
                character of sand, 154.
                details of practice, 154.
                expense of, 165.
                in the U. S., 161.
                principles of, 152.
                results of, 159.
 Saturated solutions, 6.
 Schizomycetes,  19.
 Schiitzenberger's oxygen method, 31.
 Schuylkill River, pollution  of, 59.
 Sediment in iron pipes,  210.
            river waters, 57.
 Sedimentation,  147.
 Seine, pollution of,  59, 61.
 Self-purifying power of  streams, 63.
 Service pipes,  211-215.
 Settling basins, 146,  147.
 Sharpies, quoted, 120.
 Sheffield, consumption of water in, 194.
 Silicated carbon for  filters, 172.
 Smart, Dr., quoted,  49, 52, 99, 100, 130.
             simple form of  filter,  174.
 Smith's process for coating pipes, 208.
 Soda-water, 12, 13.
 Softening of hard water,  181.
 Solids in solution, estimation of, 32.
       solution of, 1.
 Solubility,   curves of, 4.
            of  ammonia, 11.
               carbonic  acid, 11.
               gases,  10, 11.
               liquids, 13.
               metallic gold, 15.
               nitrogen, 11.
               solids, I.
               sulphate  of lime, 5.
 Solution and suspension distinguished, 14.
 Solution, 1.
         chemical, 2.
         means of hastening, 9, 13.
         of gases, 10.
            liquids,  13.
            solids, 1.
         physical, I.
 Solutions,  mixed, 7.
           saturated,  6.
            supersaturated,  6.
 Solvent,  term  defined,  3.
 Spaltpilze, 19.
 Spencer's carbide of  iron,  159, 166.
 Sphaerozyga, 87.
 Spirillum, -la,  20.
 Spithead, England, wells at,  121.
 Splenic fever,  cause of, 20.
 Sponge for filters, 168.
        fresh-water,  80.
        growth of in conduits,  207.
 Spongilla fluviatilis,  80.
                     analysis of, 82.
                     figure of, 81.
                     spicules of, 81  82. 
232
INDEX.
Spongy iron for filters, 166, 173.
Spree filtered at Berlin, 157, 160.
Springfield, Mass., algje at, 90.
Springs, 133.
         effect of barometric pressure on,
           141.
Standards of purity,  40.
St. Louis, artesian well at, 137.
          consumption of water at, 195.
          settling basins at, 147.
          waste of water  at, 195.
Storage, effect of, 149.
Storer,  Prof.,  quoted, 6.
Streams, pollution of, 57.
         self-purification  of, 63.
         turbidity of, 56.
                    table, 57.
Sulphate of iron test, 35.
           lime, solubility of,  5.
Sulphuretted hydrogen  in ponded water,
  85.
Supersaturated solutions,  6, 12.
Surface water,  animal and vegetable  life
                 in, 79-90.
               as a  source  of supply, 56.
               examination of, 96.
                      (Tables), 103, 104.
               tastes and odors of, 90.
               temperature of, 91.
               variations of, 100.
Suspended matter, determination of, 29.
                  in Missouri R., 147.
                  in streams, 57.
Suspension defined,  14.

Tables for facilitating calculations, 221-
  225.
Tank filters, 172.
Taunton,  Mass., filter gallery at, 108.
                ground water near, 105.
Temperature, change of in conduits, 207.
             means of measuring, 95.
             of Fresh Pond, Mass., 94.
                ground  water  supplies,
                  118.
                London water,  93.
                surface waters, 91.
Thames water filtered, 159, 160.
The Hague, water supply of, 121.
Thermometers, 95.
Tidy, Dr., classification of waters, 42.
Toulouse,  filter gallery at, 119.
Turbidity, estimation of, 148.
           of streams. 56.
Turbid water, clarification of,  15.
Typhoid fever and drinking water, 22.

UlXiK, quoted, 71.
Unpolluted  water from various sources
  (Table), 145.

Vegetable growth on  filter beds, 164.
Vibrio (-nes), 20.
Vienna, water supply of, 133,  207.
Virginia City, Nev., conduit, 211.
Vistula, suspended matter in, 57.
Vlissingen.  See  Flushing.

Wanklyn, quoted, 41.
Wanklyn's method of analysis, 38.
Waste of water, 194-206.
       detection of, Bell's system, 201.
                   Church's method, 202.
                   Deacon's system, 196.
       in winter,  205.
       prevention of, 196.
Water analysis, 29.
Waters, classification of, 17.
Weights and measures, tables  of, 221-
  225.
Well at Whiston,  Eng., 139, 140.
        Brooklyn, N. Y.,  ill.
Wells, artesian, 133.
       deep, 134, 139.
        effect of pumping from, 109.
       near salt water, 121.
       pollution of, 128.
       shallow, 106.
Well water, examination of, 131.
                           (Table), 132,
Whiston,  Eng., deep well at, 139,  140.
Whitman,  T. J., quoted, 195.
Wood charcoal for filters, 168, 174.
Wooden pipes, 211.
Worcester, sewage of, 62.
Wrought-iron pipes, 210.

Zurich, filtration at, 157.
Zymotic diseases,  18. 
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 * Drinker's Tunnelling.....................4to, half morocco,  25 00
 Eissler's  Explosives—Nitroglycerine  and Dynamite........8vo,   4 00
 Gerhard's Sanitary House Inspection....................16mo,   1 00
 Godwin's Railroad Engineer's Field-book. 12mo, pocket-bk. form,   2 50
 Gore's Elements of Geodesy...........................Svo,   2 50
Howard's Transition Curve Field-book.....12mo, morocco flap,   1  50
Howe's Retaining Walls (New Edition.).................12mo,   1  25
                                7 
Hudson's Excavation Tables.  Vol. II...................  8vo,   $1 00
Hutton's Mechauical Engineering of Power Plants........8vo,    <> 00
Johnson's Materials of  Construction......................8vo,    6 00
Johnson's Stadia Reduction Diagram. .Sheet, 22i X  28£ inches,      50
    "    Theory and Practice of Surveying............... 8vo,    4 00
Kent's Mechanical Engineer's Pocket-book.....12mo, morocco,    5 00
Kiersted's Sewage Disposal............................12mo,    1 25
Kirkwood's Lead Pipe for Service Pipe...................8vo,    1 50
Mahan's Civil Engineering.   (Wood.)....................8vo,    5 00
Merriman and Brook's Handbook for Surveyors---12mo,  mor.,    2 00
Merriman's Geodetic Surveying.......................... .8vo,    2 00
     "     Retaining Walls and Masonry Dams..........8vo,    2 00
Mosely's Mechanical Engineering.  (Mahan.).............8vo,    5 00
Nagle's Manual for Railroad Engineers........12mo, morocco,    3 00
Patton's Civil Engineering.............................-8vo,    7 50
        Foundations....................................8vo,    5 00
Rockwell's Roads and Pavements in France............12mo,    1 25
Ruffner's Non-tidal Rivers:..............................8vo,    1 25
Searles's Field Engineering...............12mo, morocco  flaps,    3 00
    "   Railroad Spiral.................12mo, morocco  flaps,    1 50
Siebert and Biggin's Modern Stone Cutting and Masonry.. .8vo,    1 50
Smith's Cable Tramways.................................4to,    2 50
   "   Wire Manufacture and Uses......................4to,    3 00
Spalding's Roads and Pavements.......................12mo,   2 00
     "    Hydraulic Cement..........................12mo,    2 00
Thurston's Materials of Construction .....................8vo,    5 00
* Trautwine's Civil Engineer's Pocket-book. ..12mo, mor. flaps,   5 00
*      "     Cross-section............................Sheet,     25
*      •'     Excavations and Embankments.............8vo,   2 00
*      "     Laying  Out Curves............12mo, morocco,   2 50
Waddell's De Pontibus (A Pocket-book for Bridge Engineers).
                                           12mo, morocco,    3 00
Wait's Engineering and  Architectural Jurisprudence.......8vo,    6 00
                                                   Sheep,    6 50
Warren's Stereotomy—Stone Cutting.....................8vo,    2 50
Webb's Engineering Instruments..............12mo, morocco,    1 00
Wegmann's Construction of Masonry Dams...............4to,    5 00
Wellington's Location of Railways.......................8vo,    5 00
                                8 
 Wheeler's Civil Engineering..............................8vo,  $4 00
 Wolff's Windmill as a Prime Mover......................8vo,   3 00
                         HYDRAULICS.
   Water-wheels—Windmills—Service Pipe—Drainage, Etc.
                   (See also Engineering, p. 6.)
 Bazin's Experiments upon the Contraction of the Liquid Vein
      (Trautwine).......................................8vo,   2 00
 Bovey's Treatise on Hydraulics...........................8vo,   4 00
 Coffiu's Graphical Solution of Hydraulic Problems.......12mo,   2 50
 Ferrel's Treatise on the Winds, Cyclones, and Tornadoes.. .8vo,   4 00
 Fuerte's Water and Public Health......................12mo,   1 50
 Ganguillet & Kutter'sFlow of Water. (Hering& Trautwine.).8vo,   4 00
 Hazeu's Filtration of Public Water Supply................8vo,   2 00
 Herschel's 115 Experiments .............................8vo,   2 00
 Kiersted's Sewage Disposal............................12mo,   1 25
 Kirkwood's Lead Pipe for Service Pipe..................8vo,   1 50
 Mason's Water Supply...................................8vo,   5 00
 Merrimau's Treatise ou Hydraulics..,....................8vo,   4 00
 Nichols's Water Supply (Chemical and Sanitary)..........8vo,   2 50
 Ruffner's Improvement for Non-tidal Rivers..............8vo,   1 25
 Wegmaun's Water Supply of the City of New York.......4to,  10 00
 Weisbach's Hydraulics.   (Du Bois.)......................8vo,   5 00
 Wilson's Irrigation Engineering,.........................8vo,   4 00
 Wolff's AVindmill as a Prime Mover......................8vo,   3 00
 Wood's Theory of Turbiues.............................8vo,   2 50
                      MANUFACTURES.
   Aniline—Boilers—Explosives—Iron—Sugar—Watches-
                        Woollens,  Etc.
 Allen's Tables for Iron Analysis..........................8vo,   3  00
 Beaumout's Woollen and Worsted Manufacture.........12mo,   1  50
 Bolland's Encyclopaedia of Founding Terms___........12mo,   3 00
        The Iron  Founder.............................12mo,   2 50
   "     "   "     "    Supplement.................12mo,   2 50
Booth's Clock and Watch  Maker's Manual...............12mo,   2 00
Bouvier's Handbook on Oil Painting....................12mo,   2 00
Eissler's Explosives, Nitroglycerine and Dynamite........8vo,   4 00
Ford's Boiler Making for Boiler Makers.................18mo,   1  00
Metcalfe's Cost of Manufactures.........................8vo,   5  00
                               9 
 Metcalf's Steel—A Manual for Steel Users...............12mo,   $2 00
 Reimann's Aniline Colors.  (Crookes.)....................8vo,    2 50
 * Reisig's Guide to Piece Dyeing.........................8vo,   25 00
 Spencer's Sugar Manufacturer's Handbook... .12mo, mor. flap,    2 00
     "    Handbook   for  Chemists   of   Beet   Houses.
                                           12mo, mor. flap,    3 00
 Svedelius's Handbook for Charcoal Burners..............12mo,    1 50
 The Lathe and Its Uses................................ 8vo,    6 00 •
 Thurston's Manual of Steam Boilers...................... 8vo,    5 00
 Walke's Lectures on Explosives..........................8vo,    4 00
 West's American Foundry Practice.....................12mo,    2 50
    "   Moulder's Text-book...........................12mo,    2 50
 Wiechmann's Sugar Analysis............................8vo,    2 50
 Woodbury's Fire Protection of Mills......................8vo,    2 50


                MATERIALS OF ENGINEERING.
             Strength—Elasticity—Resistance, Etc.
                   (See also Engineering, p. 6.)
 Baker's Masonry Construction.............................8vo,    5 00
 Beardslee and Kent's Strength of Wrought Iron...........8vo,    1 50
 Bovey's Strength of Materials............................8vo,    7 50
 Burr's Elasticity and Resistance of Materials...............8vo,    5 00
 Byrne's Highway Construction...........................8vo,    5 00
 Carpenter's Testing Machines and Methods of Testing Materials.
 Church's Mechanics of Engineering—Solids and Fluids.....8vo,    6 00
 Du Bois's Stresses in Framed Structures...................4to,   10 00
 Hatfield's Transverse Strains.............................8vo,    5 00
 Johnson's Materials of Construction......................8vo,    6 00
 Lanza's Applied Mechanics...............................8vo,    7 50
    "   Strength of Wooden Columns.............8vo, paper,      50
 Merrill's Stones for Building and Decoration..............8vo,    5 00
• Merriman's Mechanics of Materials............„...........8vo    4 00
            Strength of Materials...................... 12mo    1 00
 Patton's Treatise on Foundations.........................8vo    5 00
 Rockwell's Roads and Pavements in France.............12mo    1 25
 Spalding's Roads and Pavements.......................12mo    2 00
 Thurston's Materials of Construction....................8vo    5 00
                                10 
  Thurston's Materials of Engineering...............3 vols., 8vo,  $8 00
       Vol. I., Non-metallic  ............................8vo,   2 00
       Vol. II., Iron and Steel............................8vo,   3 50
       Vol. III., Alloys, Brasses, and Bronzes.............8vo,   2 50
 Weyrauch's Strength of Iron and Steel.  (Du Bois.)........8vo,   1 50
 Wood's Resistance of Materials...........................8vo,   2 00

                         MATHEMATICS.
            Calculus—Geometry—Trigonometry, Etc.
 Baker's  Elliptic Functions...............................8vo,   1 50
 Ballard's Pyramid Problem..............................8vo,   1 50
 Barnard's  Pyramid Problem.............................8vo,   1 50
 Bass's Differential Calculus............................12mo    4 00
 Brigg's Plane Analytical Geometry......................12mo,   1 00
 Chapman's Theory of Equations........................12mo,   1 50
 Chessin's Elements of the Theory of Functions.
 Compton's Logarithmic Computations...................12mo,   1 50
 Craig's Linear Differential Equations.....................8vo,   5 00
 Davis's Introduction to the Logic of Algebra..............8vo,   1 50
 Halsted's Elements of Geometry.........................8vo,   175
     "   Synthetic Geometry............................8vo,   150
 Johnson's Curve Tracing...............................12mo,   1 00
         Differential Equations—Ordinary and Partial.....8vo,   3 50
         Integral Calculus............................12mo,   150
     "                   Unabridged.
         Least Squares................................12mo,   150
 Ludlow's Logarithmic and Other Tables.  (Bass.).........8vo,    2 00
     "   Trigonometry with  Tables.  (Bass.).............8vo,   3 00
 Mahan's  Descriptive Geometry (Stone Cutting).... .......8vo,   1  50
 Merriman and Woodward's Higher Mathematics..........8vo,   5 00
 Merriman's Method of Least Squares.....................8vo,    2  00
 Parker's  Quadrature of the Circle........................8vo,    2  50
 Rice and Johnson's Differential and Integral Calculus,
                                         2 vols, in 1, 12mo,   2 50
        "         Differential Calculus...................8vo,   3 00
                  Abridgment of Differential Calculus___8vo,   1 50
Searles's Elements  of Geometry........................8vo,   1 50
Totteu's Metrology......................................8vo,   2 50 '
Warren's Descriptive Geometry...................2 vols.,  8vo,   3 50
    "    Drafting Instruments........................  12mo,   125
    "    Free-hand Drawing..........................12mo,   100
    "    Higher Linear Perspective......................8vo,   3 50
    "    Linear Perspective...........................12mo,   100
    "    Primary Geometry...........................12mo,     75
                               11 
 Warren's Plane Problems .............................12mo,  $1 2o
          Plane Problems..............................12mo,    125
     "    Problems and Theorems........................8vo,    2 50
          Projection Drawing..........................12mo,    150
 Wood's Co-ordinate Geometry............................8vo,    2 00
        Trigonometry.................................12mo,    1 00
 Woolf's Descriptive Geometry.....................Royal 8vo,    3 00

                  MECHANICS-MACHINERY.
                Text-books  and Practical Works.
                    (See also Engineering,  p. 6.)
 Baldwin's Steam Heating for Buildings..................12mo,    2 50
 Benjamin's Wrinkles and Recipes.......................12mo,    2 00
 Carpenter's Testing Machines and  Methods of Testing
       Materials..........................................8vo.
 Chordal's Letters to Mechanics.....................---12mo,    2 00
 Church's Mechanics of Engineering....................8vo,    6 00
          Notes and Examples in Mechanics..............8vo,    2 00
 Crehore's Mechanics of the Girder........................8vo,    5 00
 Cromwell's Belts and Pulleys......................... 12mo,    1 50
      "     Toothed Gearing..........................12mo,    150
 Compton's First Lessons  in Metal Working..............12mo,    1 50
 Daua's Elementary Mechanics.........................12mo,    1 50
 Dingey's Machinery Pattern Making....................12mo,    2 00
 Dredge's  Trans.  Exhibits  Building,   World   Exposition,
                                          4to, half morocco,   10 00
 Du Bois's Mechanics.  Vol. I., Kinematics..............8vo,    3 50
                      Vol. II., Statics.................8vo,    4 00
                      Vol. III., Kinetics.............. .8vo,    3 50
 Fitzgerald's Boston Machinist...........................18mo,    1 00
 Flather's Dynamometers.......■.........................12mo,    2 00
          Rope Driving................................12mo,    2 00
 Hall's Car Lubrication.................................12mo,    1 00
 Holly's Saw Filing....................................18mo,     75
 Johnson's Theoretical Mechanics.   An  Elementary Treatise.
       (In the press.)
t Jones Machine Design.   Part I., Kinematics..............8vo,    1 50
                        Part II., Strength and Proportion of
       Machine Parts.
 Lanza's Applied Mechanics..............................8vo    7 50
 MacCord's Kinematics..................................8vo,   5 00
 Merriman's Mechanics of Materials.......................8vo,   4 00
 Metcalfe's Cost of Manufactures..........................8vo    5 00
 Michie's Analytical Mechanics............................8vo,   4 00
                                12 
Mosely's Mechanical Engineering.  (Mahan.)..............8vo,  $5 00
Richards's Compressed Air.............................12mo,   1 50
Robinson's Principles of Mechanism.................... 8vo,   3 00
Smith's Press-working of Metals.........................8vo,   3 00
The Lathe and Its Uses................................. 8vo,   6 OO
Thurston's Friction and Lost Work......................8vo,   3 00
     "    The Animal as a Machine...................12mo,   100
Warren's Machine Construction..................2 vols., 8vo,   7 50
Weisbach's Hydraulics and Hydraulic Motors.  (Du Bois.)..8vo,   5 00
     "     Mechanics  of Engineering.   Vol.  III.,  Part  I.,
      Sec. I.   (Klein.)...................................8vo,   5 00
Weisbach's Mechanics  of  Engineering.  Vol.  III.,  Part  I.,
      Sec. II.   (Klein.).................................8vo,   5 00
Weisbach's Steam Engines.  (Du Bois.)...................8vo,   5 00
Wood's Analytical Mechanics............................8vo,   3 00
   "   Elementary Mechanics.........................12mo,   125
   "       "         "     Supplement and Key...........   1 25

                        METALLURGY.
               Iron—Gold—Silver—Alloys, Etc.

Allen's Tables for Iron Analysis..........................8vo,   3 00
Egleston's Gold and Mercury............................8vo,   7 50
     "     Metallurgy of Silver......................... 8vo,   7 50
* Kerl's Metallurgy—Copper and Iron....................8vo,  15 00
*          "        Steel, Fuel, etc.....................8vo,  15 00
Kunhardt's Ore Dressing in Europe.......................8vo,   1 50
Metcalf Steel—A Manual for Steel Users...............12mo,  . 2 00
O'Driscoll's Treatment of Gold Ores......................8vo,   2 00
Thurston's Iron and Steel................................8vo,   3 50
    "      Alloys.......................................8vo,   2 50
Wilson's Cyanide Processes............................12mo,   1 50

                 MINERALOGY  AND MINING.
       Mine Accidents—Ventilation—Ore Dressing, Etc.

Barringer's Minerals of Commercial Value---oblong morocco,   2 50
Beard's Ventilation of Mines.......................12mo,   2 50
Boyd's Resources of South Western Virginia..............8vo,   3 00
   "   Map of South Western Virginia.....Pocket-book form,   2 00
Brush  and Penfield's Determinative Mineralogy..........8vo,   3 50
Chester's Catalogue of Minerals..........................8vo,   1 25
    .<       "      "    "    ........................paper,     50
    "    Dictionary of  the Names of Minerals.............8vo,   3 00
Dana's American Localities of Minerals...................8vo,   1 00
                                13 
Dana's Descriptive Mineralogy.   (E. S.) ... .8vo, half morocco, $12 50
   "  Mineralogy aud Petrography  (J.D.)............12mo,   2 00
   "  Minerals and How to Study Them.  (E. S.).......12mo,   1 50
   "  Text-book of Mineralogy.  (E. S.).................8vo,   3 50
^Drinker's Tunnelling, Explosives, Compounds, aud Rock Drills.
                                        4to, half morocco,  25 00
Eglestou's Catalogue of Minerals and Synonyms...........8vo,   2 50
Eissler's Explosives—Nitroglycerine and Dynamite........8vo,   4 00
Goodyear's Coal Mines of the Western Coast............12mo,   2 50
Hussak's Rock-forming Minerals. (Smith.)...............8vo,   2 00
Ihlseng's Manual of Mining.............................8vo,   4 00
Kunhardt's Ore Dressing in Europe......................8vo,   1 50
O'Driscoll's Treatment of Gold Ores......................8vo,   2 00
Rosenbusch's Microscopical Physiography  of Minerals  aud
      Rocks.  (Iddings.)................................8vo,   5 00
Sawyer's Accidents in Mines............................8vo,   7 00
Stockbridge's Rocks and Soils............................8vo,   2 50
Walke's Lectures on Explosives..........................8vo,   4 00
Williams's Lithology....................................8vo,   3 00
Wilson's Mine Ventilation.............................16mo,   125
    "   Placer Mining...............................12mo.

    STEAM AND ELECTRICAL ENGINES,  BOILERS, Etc.

     Stationary—Marine—Locomotive—Gas  Engines, Etc.
                   (See also Engineering, p. 6.)
Baldwin's Steam Heating for Buildings.................12mo,   2 50
Clerk's Gas Engine..................................12mo,   4 00
Ford's Boiler Making for Boiler  Makers.................18mo,   1 00
Hemenway's Indicator Practice.........................12mo,   2 00
Hoadley's Warm-blast Furuace...........................8vo,   1 50
Kneass's Practice and Theory of the Injector.............8vo,    1 50
MacCord's Slide Valve..................................8vo,   2 00
* Maw's Marine Engines..................Folio, half morocco,  18 00
Meyer's Modern Locomotive Construction.................4to,   10  00
Peabody and Miller's Steam Boilers.......................8vo,    4  00
Peabody's Tables of Saturated Steam.....................8vo,    1  00
     "    Thermodynamics of the Steam Engine......... 8vo,   5 00
     "    Valve Gears for the Steam-Engine..............8vo,   2 50
Pray's Twenty Years with the Indicator............Royal 8vo,   2 50
Pupin and Osterberg's Thermodynamics................12mo,   1 25
 Reagan's  Steam and Electrical Locomotives............12mo,   2 00
Rontgen's Thermodynamics. ' (Du Bois.).................8vo,   5 00
Sinclair's Locomotive Running.........................12mo,   2 00
Thurston's Boiler Explosion...........................12mo,   1 50
                               14 
Thurston's Engine and Boiler Trials......................8vo,  $5 00
          Manual of the  Steam Engine.  Part I., Structure
              and Theory...............................8vo,   7 50
          Manual of the  Steam Engine.   Part II.,  Design,
              Construction, and Operation...............8vo,   7 50
                                                  2 parts,  12 00
          Philosophy of the Steam Engine.............12mo,     75
          Reflection on the Motive Power of Heat. (Carnot.)
                                                   12mo,   1 50
          Stationary Steam Engines...............___12mo,   1 50
          Steam-boiler Construction and Operation.......8vo,   5 00
Spangler's Valve Gears..................................8vo,   2 50
Trowbridge's Stationary Steam Engines...........4to, boards,   2 50
Weisbach's Steam Engine.  (Du Bois.)...................8vo,   5 00
Whitham's Constructive Steam Engineering.............. ..8vo,  10 00
          Steam-engine  Design.........................8vo,   6 00
Wilson's Steam Boilers.  (Flather.).....................12mo,   2 50
Wood's Thermodynamics, Heat Motors, etc...............8vo,   4 00

           TABLES, WEIGHTS, AND MEASURES.

    For Actuaries, Chemists, Engineers, Mechanics—Metric
                         Tables, Etc.
Adriance's Laboratory Calculations.....................12mo,   1 25
Allen's Tables for Iron Anah/sis..........................8vo,   3 00
Bixby's Graphical Computing Tables.........,.........Sheet,     25
Compton's Logarithms.................................12mo,   1 50
Crandall's Railway and Earthwork Tables...............8vo,   1 50
Egleston's Weights and Measures.......................18mo,     75
Fisher's Table of Cubic Yards.....................Cardboard,     25
Hudson's Excavation Tables.   Vol.11....................8vo,   100
Johnson's  Stadia and Earthwork Tables..................8vo,   1 25
Ludlow's Logarithmic and Other Tables.   (Bass.).......12mo,   2 00
Thurston's Conversion Tables............................8vo,   1 00
Totten's Metrology......................................8vo,   2 50

                        VENTILATION.
     Steam  Heating—House Inspection—Mine Ventilation.
Baldwin's Steam Heating...............................12mo,   2 50
Beard's Ventilation of Mines...........................12mo,   2 50
Carpenter's Heating and  Ventilating of Buildings..........8vo,   3 00
Gerhard's  Sanitary House Inspection............Square 16mo,   1 00
Mott's The Air We Breathe, and Ventilation............16mo,   1 00
Reid 's Ventilation of American Dwellings..............12mo,   1 50
Wilson's Mine Ventilation..............................16mo,   1 25
                               15 
HISCELLANEOUS  PUBLICATIONS.
1	50
1	50
2 00	
1	50
4 00	
2	50
1	00
1	50
3 00	
Alcott's Gems, Sentiment, Language...............Gilt edges,  $5 00
Bailey's The New Tale of a Tub.................,........8vo,     75
Ballard's Solution of the Pyramid Problem...............8vo,
Barnard's The Metrological System of the Great Pyramid. .8vo,
Davis's Elements of Law................................8vo,
Emmon's Geological Guide-book of the Rocky Mountains. .8vo,
Ferrel's Treatise on the Winds...........................8vo,
Haines's Addresses Delivered before^the Am. Ry. Assn. ..12mo.
Mott's The Fallacy of the Present Theory of Sound. .Sq.  16mo,
Perkins's Cornell University......................Oblong 4to,
Ricketts's History of Rensselaer  Polytechnic Institute.....8vo,
Rotherham's  The  New Testament  Critically  Emphasized.
                                                    12mo,    1 50
     "       The Emphasized New Test.   A new translation.
                                               Large 8vo,    2 00
Totten's An Important Question  in Metrology.............8vo,    2 50
Whitehouse's Lake  Mceris.............................Paper,     25
* Wiley's Yosemite, Alaska, and  Yellowstone.............4to,    3 00

          HEBREW AND CHALDEE  TEXT=BOOKS.
          For Schools and Theological Seminaries.
Gesenius's Hebrew  and  Chaldee Lexicon to Old  Testament.
      (Tregelles.)....................Small 4to, half morocco,    5 00
Green's Elementary Hebrew Grammar..................12mo,    1 25
   "   Grammar of the  Hebrew Language (New Edition).8vo,    3 00
   "   Hebrew Chrestomathy...........................8vo,    2 00
Letteris's Hebrew  Bible (Massoretic  Notes in English).
                                           8vo, arabesque,    2 25
Luzzato's Grammar of the Biblical Chaldaic Language and  the
      Talmud Babli Idioms............................12mo,    1 50

                           MEDICAL.
Bull's Maternal Management in Health and Disease.......12mo,    1 00
Hammarsten's Physiological Chemistry. (Mandel.)........8vo,    4 00
Mott's Composition,  Digestibility, and Nutritive Value of Food.
                                     Large mounted chart,    1 25
Ruddiman's Incompatibilities in Prescriptions............8vo,    2 00
Steel's Treatise on the Diseases of the  Ox................8vo,    6 00
      Treatise on the Diseases of the  Dog................8vo,    3  50
Worcester's  Small Hospitals—Establishment and Maintenance,
      including  Atkinson's  Suggestions for  Hospital  Archi-
      tecture.........................................12mo,   125
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US DeporlmenI of    Health. Education,   ond Welfare. Public
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