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SURGEON GENERAL'S OFFICE
    LIBRARY.
Section,
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EXAMINATION OF WATER.
LEFFMANN.
I
 
BY THE SAME AUTHOR.
          ANALYSIS
                OF
MILK  AND MILK  PRODUCTS.
         SECOND EDITION.
   i2mo.  120 pages. Illustrated.  Net, $1.25.
    SANITARY RELATIONS
             OF THE
COAL-TAR  COLORS
       BY THEODORE WEYL.
  AUTHORIZED TRANSLATION.
      i2mo. 154 pages. Net, $1.25.
P. BLAKISTON'S SON & CO., Philadelphia. 
Examination  of  Water
SANITARY AND TECHNIC PURPOSES.
     HENRY LEFFMANN, A.M., M.D., Ph.D.,
PROFESSOR OF CHEMISTRY IN THE WOMAN S MEDICAL COLLEGE OF PENNSYLVANIA,
    IN THE PENNSYLVANIA COLLEGE OF DENTAL SURGERY, AND IN
        THE WAGNER FREE INSTITUTE OF SCIENCE.
 4t£ j^r,
FOURTH EDITION, REVISED AN\D ENLXkOEO^XXH^. JCV X
          illustration&URGZOH GENERAL'S OFFICE
OCT. --0.-1899
    PHILADELPHIA
BLAKISTON'S SON & CO.
  IOI2 WALNUT STREET
        1899 
W^iA
\
Copyright, 1899, by P. Blakiston's Son &  Co.
Press of Wm. F. Fell & Co.,
  1220-24 Sansom St.,
    philadelphia. 
      I DEDICATE THIS BOOK TO THE





             MEMORY OF





          fll>S /l&otber,




   TO WHOSE WISE PRECEPT AND EXAMPLE





           IN MY BABYHOOD





I  OWE WHATEVER MERIT MY MANHOOD  YEARS





              MAY SHOW.
VI] 
 
PREFACE.
    In  preparing the fourth edition I have not found it
necessary to make many changes.   No  great advance in
analytic methods in this field has taken place since the
publication of the third edition.   Some  improvements in
details, drawn partly  from the literature  of the  subject,
partly  from my own experience, have been inserted.
   It is opportune, however, to call attention to the more
conservative view  that is now taken  as to the value of
bacteriologic examinations.  The efforts made some years
ago  by bacteriologists  to discredit the value of chemical
analysis have failed, and it is now generally admitted that
mere microbe-counting is of  little use in judging of the
sanitary value of water samples.   The best bacteriologists
are also  free  to admit that up  to the  present time the
detection of pathogenic bacteria in water is  so  difficult a
task as to  be  rarely accomplished.  There has been so
much  inaccurate and  even dishonest  work  done in this
field that  it is incumbent on every one who reports upon
the bacteriologic examination of water samples to  give in
detail the method followed, in  order that the data may be
properly valued.
                           ix 
x
PREFACE.
  The day is  probably not  far distant  when it  will be
recognised that both chemical and bacteriologic examina-
tions of ordinary surface-waters  are  of little importance,
since such waters can not be allowed for drinking purposes
unless  efficiently  filtered.  Apart from  various  general
considerations,  the  investigations  as to  the  relations of
insects and other minute organisms as conveyors of disease
germs must lead us to regard with suspicion any water that
may receive material from the surface of the ground.
                                               H.  L.
71 j Walnut Street,
   June,  i8gg. 
CONTENTS.
 Note on Water-supply,.............   ^ffe

 Natural History and Classification of Natural Waters.
         Rain Water—Surface Water—Subsoil Water—Deep
           Water,..................   !6_22

 Analytic Operations.
     Sanitary Examinations:
         Collection and   Preliminary Examination — Total
           Solids—Chlorin—Nitrogen in Ammonium  Com-
           pounds and Organic Matter—Nitrogen as Nitrates
           —Nitrogen as Nitrites—Oxygen-consuming Power
           — Phosphates — Dissolved Oxygen — Poisonous
           Metals—Biologic Examinations,.......   23-82
     Technic Examinations:
         General Quantitative Analysis—Spectroscopic Anal-
           ysis—Specific  Gravity,............   82-98

 Interpretation of Results.
         Statement  of Analysis — Sanitary  Applications —
           Action  of Water  on Lead—Technic  Applica-
           tions—Boiler Waters—Sewage  Effluents—Purifi-
           cation of  Water—Identification of  Source  of
           Water>..................99-135
Analytic Data.
         Factors for  Calculation—Conversion Table —Rain
          and Subsoil Waters—Artesian Waters—City Sup-
          pHes,...................136-140

Index,.....................143-145



                              xi 
 
           NOTE  ON  WATER-SUPPLY.
  The human race must have recognized at an early period
the value of  an  abundant supply of pure and refreshing
water.   Pastoral communities would be obliged to guide
their movements along lines that would keep them within
convenient reach of streams  and pools for watering cattle ;
agricultural nations could only  establish themselves where
water was abundant.  Of the two classes, the former would
be much less likely to develop soil-pollution, and, accord-
ingly,  we find that it is with  agricultural  and manufac-
turing  centers—/'. <?., towns and  cities—that  the  serious
difficulties  with  regard to  water-supply arise.   Drainage
areas are easily polluted ;  in all the civilized countries the
streams receive more or  less sewage, and are correspond-
ingly  offensive to  the  senses  and dangerous  to  health.
The subsoil is better adapted to deal with  normal pollu-
tion,  but its powers are not inexhaustible,  and in time
wells  and springs become  unsafe.   The usual course  of
events  in this matter is well portrayed  by Sextus Julius
Frontinus,  who  was Water  Commissioner of Rome from
a. d.  97 to  103, and who has left us  a  comprehensive
account  of the  water-supply of that city..  He says that
from the building of the city until its four hundred and
forty-first year  (312 b. c), the  citizens  were supplied
with water  from the Tiber, or  from wells and springs.
These  springs, as with  other  nations of antiquity, were
                           13 
14
NOTE ON WATER-SUPPLY.
often credited  with healing powers, either  due to some
medicinal ingredients or because the locality was supposed
to be the abode of a minor deity,  whose  favor could be
secured in various ways.  The Roman water-supply be-
came unsatisfactory; aqueducts were built, and  these sup-
plied the city for centuries.  Two of the original aqueducts
are still in use, supplying modern Rome  with excellent
water.  The quantity of water supplied to the ancient city
during the height of the development of the aqueduct sys-
tem—the  early  part of the second century of the Chris-
tian era—is not accurately known, but Clemens Herschel,
after  careful  examination  of  all data, fixes  it at about
50,000,000 gallons a day.  Most of the supply was of
good quality,  but some  of the aqueducts delivered river
water that was frequently turbid.   No  proper filtering
basins were  in use, but  special interrupting  chambers
assisted in getting rid of the coarser suspended matters.
   Much less  is  known  of the water-supply  of  the  other
great cities of the ancient world.   Aristotle, in his " Con-
stitution of Athens,"  refers  to  an  official  designated
"Superintendent of Springs," which shows that  munici-
pal hygiene was not wholly overlooked in that city.  Jeru-
salem, during its  influential period,  was apparently well
supplied with water.  The  remains of underground  con-
duits have  been lately discovered, and  it is  known, from
several  historic allusions, that  during the prolonged sieges
which the city endured  in ancient  times,  the  inhabi-
tants did not suffer from  want  of water, although food was
scarce.  On the other hand, the besieging armies were se-
verely hampered by the  lack of water in the  district sur-
rounding the  city. 
NOTE ON  WATER-SUPPLY.
15
  In common with the general decline of intelligence and
morals which affected  Europe  during the thousand  years
from the fifth  to  the fifteenth  century, the protection of
the water-supply was but little regarded.   The aqueducts
of Rome, Athens, and Lyons fell into disuse, and even at
present are mostly represented by a few scattered  ruins
studied only by the antiquary  and historian.
   It is not appropriate to discuss the  engineering features
of ancient or modern water-supply, but it is  worth  while
to correct a wide-spread error in regard to the Roman en-
gineers.   It is often said  that  they did not know that
water will rise to its original level, and. therefore, built
extensive aqueducts  to carry water over valleys.  The fact
is  that they were  as fully aware of the principle as modern
engineers,  but it was usually cheaper for them to  build the
aqueducts than to use inverted siphons.   They did use the
latter at times.   In supplying Lyons (Lugdunum), France,
with water, a series of  seven  lead  pipes, each  about 20
centimeters in  diameter, was used to carry water across a
deep  valley. 
NATURAL HISTORY AND  CLASSIFICATION  OF
                      WATER.
  Pure  water  is  an artificial  product.   Natural  waters
always contain foreign  matters in solution and suspension,
varying  from mere traces to very large proportions.  The
properties, effects, and uses of water are considerably modi-
fied by these ingredients, and the object  of analysis is to
ascertain their character and  amount.   Since these are
largely dependent on the history of the water, a classifica-
tion based on this will be convenient.   We may distinguish
four classes of natural waters :
  Rain  Water.—Water precipitated from  the atmosphere
under any conditions, and  therefore including dew, frost,
snow, and hail.
  Surface Water.—All collections of water in free  contact
with the atmosphere, as in  streams, seas, lakes, or ponds.
  Subsoil or Ground Water.—Water  not  in free  contact
with the atmosphere, percolating or flowing through  soil
or rock at  moderate  distance below  the surface,  and
derived  in large part from the rain  or  surface water of the
district.
  Deep  or Artesian  Water.—Water accumulated  at con-
siderable depth below the  surface, from which the  subsoil
water of the district has been excluded by difficultly  per-
meable strata.
  Rain water, when gathered in the open country and
                          16 
SURFACE  WATER.
17
in the later period of a prolonged rain or snow, is the purest
form of natural water.   When collected directly, it  con-
tains but little solid  matter, this consisting principally of
ammonium  compounds and  particles  of organic matter,
living  and dead, gathered from the atmosphere.  In dis-
tricts near the sea  an appreciable amount of chlorids will
be present.   It is obvious that a prolonged rain will  wash
out the air,  but since storms are usually attended by wind,
fresh portions  of air are  continually flowing in, and thus
the water never becomes perfectly pure.  Rain water col-
lected  in inhabited districts is usually quite  impure.
   Surface Water.—Rain water in part flows off on the
surface, and gains in the proportion of suspended and dis-
solved matters, the  former being found in large amount
when the rainfall is profuse.   The wearing action of water
is dependent  on the amount and  character of these sus-
pended materials.    From the higher levels of a watershed,
the streams, more or less in  the form of torrents, gather
into larger currents, and, reaching lower  levels, become
slower in movement, and deposit much of the suspended
matter.  By admixture of the waters from widely separated
districts the character and amount of the dissolved matters
are much modified.   An action of this kind is seen in the
watershed of the Schuylkill River.  This stream rises in the
anthracite-coal region of Pennsylvania, and receiving much
refuse mine-water, becomes impregnated with iron salts and
free mineral acid, being then quite unsuitable for drinking
or  manufacturing purposes.   In its course of about one
hundred miles it  passes  over an  extensive limestone dis-
trict, and receives several large streams highly charged with
calcium carbonate.   The result is  a neutralization of the 
i8
HISTORY  AND CLASSIFICATION.
acid and  a precipitation of  the  iron and  much of the
calcium.   The river  becomes purer,  and at its junction
with the Delaware River at Philadelphia it contains neither
free sulfuric  nor hydrochloric acid,  only traces  of  iron,
and but a small amount of calcium sulfate.   In this  man-
ner there is produced a soft  water, superior to that of the
river near its source,  or to  the hard waters of the middle
Schuylkill region.
  It is obviously impossible to establish close standards of
composition for surface waters.  In the case  of rain water,
falling on  the  surface of undisturbed, unpopulated  terri-
tory, the amount  of  solids  dissolved  will be small, and
will consist principally of carbonates and sulfates.   The
water of lakes and rivers is,  however, in part derived from
springs, which  may proceed from great depths, and thus
introduce  substances  not easily soluble  in surface water,
nor derivable from the soil of the district.
  The exposure to light and air which surface water under-
goes, results in  the absorption of oxygen and loss of car-
bonic  acid, together  with  the oxidation of the organic
matter.   The diminution of  the rapidity of the current
permits the deposition of the suspended  matters, and this
occurs especially as the river approaches the sea, not only
from the retarding influence of the tidal wave, but from
the precipitating action of the salt water.
  Subsoil Water. — Water that  penetrates  the  soil
passes  to various  depths, according  to  the  porosity and
arrangement of the strata.  As a rule, it descends until it
reaches but slightly pervious formations, upon  the level ol
which  it  accumulates.   In  the  upper  layer  of soil  it
dissolves mineral  and  organic ingredients,  and  becomes 
                    SUBSOIL WATER.                  ig

 impregnated with microorganisms,  through  the  agency of
 which the organic matter undergoes important transforma-
 tions.  The water, constantly accumulating, gradually flows
 along the incline of the impervious stratum, or through its
 fissures, and  may either pass downward or emerge in  the
 form of a spring.
   Much difference is observed in the composition of sub-
 soil waters, but as a general rule they contain but a limited
 amount of mineral  substances,  and a'very small  propor-
 tion of organic matter.   In  populated  districts, however,
 a  marked  change is produced  through  admixture with
 water containing animal and vegetable products  in various
 stages of decomposition.  It is especially the organic mat-
 ter containing nitrogen that is of importance.    To this
 class belong all those compounds forming tissues  that are
 intimately associated with vital action ;  also many charac-
 teristic  excretory products.   These  bodies are mostly
 unstable,  and  as  soon as their  vitality ceases, begin  to
 decompose, partly by oxidation, partly  by splitting  up
 into simpler  forms; these  changes being  in most  cases
 brought about by microorganisms.   Among the products
 noticed in  the  early stages of such decay are substances
 which possess close analogies to the organic bases or alka-
 loids, but more susceptible  of decomposition.  They are
generally  present  in 'minute amount,  but are not  infre-
quently very  active in  their  physiologic  effect.    From
the  most  recent  researches  it seems  probable  that the
pathogenic power of many microorganisms rests not upon
any  mechanic  or  other  action  of  the germs themselves,
but  upon  the  nitrogenous  bodies  they  produce.  The
ultimate results of the processes of  decomposition  depend 
20           HISTORY AND CLASSIFICATION.
largely on circumstances.  When organic matters contain-
ing  nitrogen are subjected  to  the  action of  oxidizing
agents,  such as  alkaline  potassium  permanganate  or
chromic acid, some of the  nitrogen is  converted into
ammonium  compounds.  A  similar  result occurs  in  all
waters, but  a considerable portion  of the  organic matter
may also suffer further oxidation, and in association with
the mineral substances present form  nitrites and nitrates,
especially the latter.  This  conversion is called "nitrifi-
cation."  The  conditions  under which it occurs  have
been carefully studied by various observers, but  much  re-
search is still needed to place  the subject on a secure basis.
   Nitrification takes place under the influence of microbes,
the habitat  of which does  not extend  more than  a few
yards  below  the surface of the soil.  Percy  and  Grace
Frankland  have  isolated and described a  bacillus with
active nitrifying powers.  It is a very short, almost spheric
form,  which grows  in  ammoniacal culture-fluids and in
meat-broth, but does not grow in the usual gelatin-peptone
mixture, except  when previously cultivated in meat-broth.
The nitrifying action is probably exerted  only upon the
ammonium which is formed from the organic matter.  The
presence of  some substance capable  of neutralizing acids is
necessary to continuous action.   Calcium and magnesium
carbonates fulfil  this  function.   Nitrates are the final result
of this action; nitrites are present at any given time only
in small quantity.   Denkrification—that is, the reduction
of nitrates and nitrites  to ammonium compounds—takes
place also under the influence of microbes, and is especially
apt to  occur when considerable quantities of decomposing
organic matter are introduced.  Percy and  Grace Frank- 
DEEP  WATER.
21
 land have described several species  of bacilli which have
 active denitrifying  powers;  among these are  Bacillus
 liquidus, B. vermicularis, and B. ramosus.   A partial re-
 duction  sometimes  occurs, and  a  notable proportion of
 nitrites is found, but in the presence of actively decom-
 posing organic  matter, such as that in sewage, a complete
 reduction, even to the liberation of nitrogen, may occur.
 Jordan has described several species  found in  the sewage
 of  the city of Lawrence,  which reduce nitrates to nitrites.
   Deep Water.—Water which penetrates the fissures of
 the fundamental rock-formations may pass to great depths,
 and by following the lines of the lowest and least permeable
 strata may be transported to points far removed from those
 at which it was originally collected.  The chemical changes
 thus induced  include  most of those which  take  place at
 higher points, but the increase of pressure and temperature
 confers   increased  solvent  power.   Carbonic  acid  will
 accumulate  under conditions favorable  to the  solution of
 calcium, magnesium, and  iron  carbonates, and iron,  and
 manganese oxids may be  converted into carbonates  and
 then  dissolved.   Sulfates are  reduced to sulfids,  and
 these subsequently,  by the  action of carbonic  acid, yield
 hydrogen sulfid.  Organic matter, living and dead, plays
 an  important part,  determining the reduction  of ferric
 compounds to ferrous, and  of the sulfates to sulfids,  and
 is itself converted ultimately into ammonium compounds,
 notable quantities of which are often found in deep waters.
 Further,  it is found that nitrates  and nitrites are present
 only in  small  amount, except from  certain strata rich in
organic  matter.   In  some  cases the water acquires very
high temperature, and  dissociation  of rocks occurs  with 
22
HISTORY  AND  CLASSIFICATION.
solution of considerable amounts of silicic acid, which is
ordinarily but sparingly soluble in water.
   Masses of water thus accumulated under heat and pres-
sure may find  their way to  the  surface either through
natural fissures or be reached by borings.
   While no absolute unchangeable line can be drawn be-
tween deep and subsoil waters, yet it will  in most cases be
found that the  deep  water of  a given district,  whether
obtained through  natural  or  artificial  channels,  will  be
decidedly different in composition from  the subsoil or sur-
face water of the same, and  that the rocks passed through
in such cases will be characterized  by one or more strata,
difficultly permeable  to water, and  therefore preventing
direct communication.   The characteristic differences be-
tween surface,  subsoil, and  deep waters are clearly indi-
cated in  the table of  analyses given in the appendix.
   The fact that mere depth  is not the essential difference
between  the two classes of waters is shown by comparison
between  the  composition of  the water  from a  well at
Barren Hill, near  the northern border  of  Philadelphia
County, and a deep well at Locust Point, Baltimore.  The
former is a dug well,  130 feet deep; the latter is an arte-
sian boring  of  128  feet, which  in its  descent  passes
through  4  feet  of solid rock.   The  deeper  well  is evi-
dently supplied  by  subsoil  water.   The artesian well,
though located  100 yards from  a  brackish, sewage-laden
estuary, evidently derives no water from it.
                          Barren Hill     Locust Point
                            Well.            Well.
      Total solids,.......470.00    Less than 100.00
      Chlorin,  ........120.00             4.68
      Nitrogen as nitrates, . . . 22.00             none 
ANALYTIC  OPERATIONS.
SANITARY EXAMINATIONS.
   COLLECTION AND  PRELIMINARY EXAMINATION
                    OF SAMPLES.
   Great  care  must be taken in collecting water samples,
in order  to secure a fair representation of the supply and
to avoid  introduction of
foreign  matters.    The
five-pint   green  glass-
stoppered bottles used
for  holding   acids are
suitable for containing
the samples.   The con-
tents of one such bottle
will  suffice  for   most
sanitary or technic ex-
aminations.    Figure  i
shows  a   boxed  bottle
known   as  "Banker's
Glass  Can,"  which  I
have  found  very con-               fig. i.
venient for  transporta-
tion.   It  is  provided  with  a  hinged lid which  can be
fastened, if deemed necessary,  by a padlock.  The green
glass-stoppered bottles may be fitted  in such an arrange-
                          23
 
24              ANALYTIC OPERATIONS.

merit.   Stone jugs, casks,  or metal vessels  must not be
employed.   The bottles  used must be thoroughly rinsed
several times with the water to be  examined, filled, and
the stopper tied down or fastened by stretching a rubber
finger-cot over the stopper and lip.   If corks are  used,
they should  be new and  thoroughly rinsed.  Wax, putty,
plaster,  or similar material should not be used.
  In  taking  samples  from lakes, slow streams, or  reser-
voirs, it is necessary to submerge the bottle so as to  avoid
collecting any water that has been in immediate contact
with the air.
  In the examination of  public water-supplies,  the sample
should be drawn from a hydrant in direct connection with
the main, and  not  from  a cistern, storage-tank, or dead
end of  a pipe.  In the case  of pump-wells,  a few gallons
of water should be pumped out before taking the sample,
in order to  remove that  which has been standing in  the
pipe.
   In all cases care should be taken to fill the  vessel with
as little agitation with air as possible.
   It is important that with each sample a record be  made
of  those surroundings and conditions which might influ-
ence the character of the water,  particularly in  reference
to  sources  of pollution,  such  as proximity  to cesspools,
sewers,  or  manufacturing establishments.  The  character
and condition of the  different strata of the locality should
be noted if  possible.
   Determinations of nitrogen existing as ammonium com-
pounds and as organic matter, and of oxygen-consuming
power,  should  be  made  upon  the sample in the original
condition,  whether turbid  or clear,  but all  other estima- 
SANITARY EXAMINATIONS.
25
tions should be made upon the clear liquid.  Turbid waters
may be clarified by standing or by filtration ; for the latter
purpose Schleicher & Schiill's extra heavy No. 598  paper
is the best.   In many cases the suspended  matter  can not
be entirely removed  by filtration,  and subsidence must be
resorted  to.   The use  of a  small quantity of alum, or
aluminum  hydroxid,  as described in the section on the
purification of water,  will sometimes be  applicable as  a
means of clarifying  samples.   For the quantitative deter-
mination, the sediment  from a known volume of the water
is collected on a tared filter, dried, and weighed.
  The water from newly-dug wells is generally turbid, and
the determinations are best made  after filtration ;  but the
results will be unsatisfactory, showing a higher proportion
of organic matter than will be found when the supply be-
comes clear.
   Collection of Samples for Bacteriologic Exam-
ination.—Bacteriologic  examinations are of little value
unless made promptly on  samples  that have been collected
with precautions against contamination.   The inoculation
of the culture-medium  is  best done at the source.   If this
is  not  possible,  glass-stoppered  bottles  holding  about
200 c.c.,  which have  been  thoroughly  sterilized,  with
stoppers in place, in a hot-air oven at  no° C,  must be
used for collection.  They should be rinsed on the outside
with  the water, dipped  below the  surface,  the  stopper
withdrawn, and again inserted when the bottle is full.   If
these are  to  be transported any  distance, they should be
packed in ice.   For delivering  the measured volume  of
water, a pipet sterilized  in the hot-air oven should be used.
   Color.—A colorless glass tube, two feet long and two 
26
ANALYTIC  OPERATIONS.
inches in  diameter, is closed  at each end  with a disc of
colorless glass.  An opening for filling and emptying the
tube should be made at one end, either by cutting a small
segment off the glass disc, or cutting out a small segmental
section of the tube itself before the disc is  cemented on.
A good cement for such purposes is the following :

      Caoutchouc,............   2 parts.
      Mastic,...............   6   "
      Chloroform,  ............loo   "

  The ingredients are mixed and allowed to stand for a
few days.   The cement should be used as soon as solution
is effected, as it becomes viscid on standing.
  The tube  must be about half filled with the water to be
examined, brought into a horizontal  position, level  with
the eye, and directed toward a brightly illuminated white
surface.  The comparison of tint has  to be made between
the lower  half of the tube containing the water under ex-
amination and the upper half containing air  only.
  A more convenient  form  of  tube is made by attaching
brass screw-nipples to each end of the tube, and  closing
these by screw-caps carrying plate-glass discs.  Such tubes
can be obtained from dealers in chemical apparatus.   It is
obvious that various methods of comparing color and tur-
bidity may be devised, but data  so obtained are  of little
analytic value, and even that little is  limited to samples
closely analogous in character.
  By determining the amount  of ammonium chlorid re-
quired to produce with a standard quantity of Nessler solu-
tion a color equal in depth to that of the water sample, a
means of recording  the color  with some precision  may 
SANITARY  EXAMINATIONS.              27
often be obtained.  The manipulation is conducted as de-
scribed in connection with the determination of ammonium
compounds, using equal volumes of the sample and of dis-
tilled water in separate cylinders.   The  Nessler solution
is, of  course, added only  to  the distilled water.   The
volume of diluted  standard ammonium  chlorid solution
which  must be added to the distilled water to  enable it
to produce with  the Nessler reagent a color equal to that
of the  sample is taken as an  index  of the color of the
latter.   Thus " color = 0.3 " means that the color of the
sample equals that produced by Nessler solution in distilled
water to which 0.3  c.c.  of the diluted standard ammonium
chlorid solution has been added.
   Allen Hazen has devised a standard for color compari-
son which he claims as capable of most satisfactory use on
all ordinary waters.  It is based upon the modification of
a  solution of platinum  chlorid  by a  solution  of cobalt
chlorid, as follows  :
   1.246  grams  of platinum  chlorid  (corresponding to
0.5  gram  of Pt) and 1 gram of cobalt chlorid  (corres-
ponding to  0.25 gram  of Co)  are dissolved  in water,
100 c.c. of strong  hydrochloric acid added, and the  solu-
tion made up to  1000 c.c.  It keeps  well, even when
exposed  to the  light.   For comparison,  1, 2, 3,  etc., of
the stock  solution  are  diluted to 50 c.c. in Nessler tubes.
These  correspond  to o. 1, 0.2, 0.3, etc., degrees of the
color  standard.   These also  keep for a long time if pro-
tected from  dust.   Direct comparison in 200  mm. tubes
is generally sufficient.   If the shade of color is not exactly
that of the water, more cobalt may be added, the platinum
being  constant.  Hazen  expresses the result in  any case 
28
ANALYTIC OPERATIONS.
in terms of  "the amount of platinum in parts per 10,000,
which  in acid solution with so much  cobalt as will match
the hue, produces an equal color in distilled water."
   Lovibond's tintometer is  probably the best means of
making color comparisons.
   Odor.—Put about 150 c.c.  of  the water  into a clean,
wide-mouth 250  c.c. stoppered  bottle, which has been
previously rinsed  with the same water; insert  the stopper
and warm the water in a water-bath to 1000  F.  Remove
the bottle from the water-bath and shake it rapidly for a
few seconds ; remove the stopper, and immediately note if
the water has any smell.  Insert  the  stopper  and repeat
the test.
   In a polluted water the odor will sometimes give a clue
to the origin of the pollution.
   Reaction.—The determination of reaction is usually
made by the addition of a neutral solution of litmus to the
water.   If an acid reaction is obtained, the water should
be boiled in order to  determine  if it is due to carbonic
acid.    Some  of  the more delicate  indicators, such  as
phenolphthale'in,  lakmoid,  and erythrosin,  may be  used
with advantage for these tests.   The latter possesses  the
advantage that it is unaffected by carbonic  acid, but de-
tects even traces of free mineral acid.   It is neutral, also,
to many normal  metallic  salts, such as ferrous sulfate,
which  are acid to litmus.  Ferric  salts, however, are acid
to lakmoid.   Its color-changes are the same as those of
litmus—/. <?., red  with acids and blue with alkalies.
   Phenolphthale'in is usually applied to  the  detection of
weak acids,  such  as carbonic acid  and the organic acids.
In acid and neutral solutions it is colorless;  in alkaline, 
SANITARY  EXAMINATIONS.
29
red.   Nearly all waters contain  carbonic  acid, and  will
therefore bleach a  solution of phenolphthale'in which has
been reddened by a small amount of alkali.
  For indicators employed in quantitative  determinations
of alkalinity see under " Hardness."

                    TOTAL SOLIDS.
  A platinum basin  holding 100 c.c.  will be found con-
venient for  this determination.  This will  weigh about
45  grams.   It  should be  kept clean  and smooth  by
frequent burnishing with sand, a  little  of which should be
placed in the  palm of the hand, moistened, and the dish
gently rubbed against it.  Very fine sea-sand with round,
smooth grains is the  only kind  suitable for  this  purpose.
Coarse river sand, tripoli, or other rough scouring-powders
must not be employed.   If proper care is taken, the luster
of the metal  will be  retained, and the loss in weight will
be trifling.  The inner surface can generally be cleaned by
treatment with hydrochloric acid,  rinsing, and, if necessary,
burnishing with sand.  Neglect  of these  precautions will
soon lead to serious damage to the dish.   A small, smooth
slab of iron or marble is convenient to  set it on while cool-
ing.  When being heated over the naked flame, the  dish
should rest on a triangle  of iron wire, covered with pipe-
stems.   Dishes of pure nickel are not satisfactory substi-
tutes for those of platinum.
  Platinum-pointed  forceps should be used  in handling
the dish.   The platinum terminals may be  kept bright and
clean by the use of sand.
  The low-temperature burner, used as shown in figure 2,
will be found a very convenient substitute for the water- 
3°
ANALYTIC  OPERATIONS.
bath and hot-air oven.   The inlet pipe is very short  and
soon  becomes so hot as to injure  the  rubber tube.  To
avoid this it may be lengthened by means of a piece of
j^j-inch gas-pipe, or the junction may be wrapped with a
rag, the ends  of  which dip  into  water.   By  capillary
attraction the rag is kept moist and  cool.
   The determination of total solids is made by evaporating
ioo c.c.  of the  water  in  the  platinum basin, which has
been previously heated  almost  to redness, allowed to cool
for ten minutes, and weighed.  The operation is conducted
                        at a moderate  heat.  When the
                        residue  appears  dry,  the  heat
                        may  be increased  slightly for
                        some minutes.  The above meth-
                        od will answer  in most cases.
                        In waters  of exceptional purity
                        it maybe advisable to use larger
                        quantities,  such  as  250  c.c.
                     i  When the residue contains deli-
                        quescent bodies, the determina-
                        tion  will  not  be accurate, and
                        when appreciable  amounts  of
magnesium and chlorin  are present, a decomposition will
occur toward the close of the  evaporation by which mag-
nesium oxid will be formed and hydrogen chlorid escape.
   The irregular decomposition occurring during the evap-
oration may be  largely prevented by  adding 0.005 gram of
sodium carbonate  to each  100 c.c. of  the sample taken.
This converts magnesium and calcium salts into carbonates.
The sodium carbonate is conveniently kept in the form of
solution of such strength that 1 c.c.  contains 0.001 gram.
 
SANITARY  EXAMINATIONS.
31
The weight of the carbonate is, of course, to be deducted
from the weight of the residue.  Drown  and Hazen have
carefully investigated this method and have found it avail-
able for a  more satisfactory determination of the loss  on
ignition.   For this process they place the platinum basin
containing the residue within another similar basin of such
size that an air-space of about one-half of an inch is left all
around the inner dish, which is supported upon a spiral of
platinum that rests on the bottom of the outer dish.  Over
the  inner  dish is suspended  a disc of  platinum  foil to
reflect the  heat.  The outer dish is heated to bright red-
ness.
   After the  weight  of the residue  is obtained, the dish
should be cautiously heated to low redness and  the effect
noted.   Nitrates  and  nitrites,  calcium  and  magnesium
carbonates, are decomposed ;  ammonium salts are driven
off; potassium  and  sodium chlorids are also_driven  off
if the temperature  is high.  Organic matter is at first
charred, and by continued heating burned off.   When the
quantity of nitrates is considerable, slight  deflagration may
be observed, or the production of red fumes of nitrogen
dioxid.   The organic matter,  in decomposing, not infre-
quently develops  odors which indicate  its character  or
source.   These are  more  satisfactorily observed when a
rather large quantity, say 250 c.c, is evaporated at a low
heat, preferably on a water-bath.
   In water of high organic purity, the residue on heating
will give  no appreciable blackening nor odor, while in
forest streams charged with vegetable matter derived from
falling leaves, very decided blackening without unpleasant
odor will  be noticed.   The loss  of weight after heating 
32
ANALYTIC OPERATIONS.
can not be taken as a measure of the organic matter, except
when present in relatively large amount.

                      CHLORIN.
Solutions  Required:
  Standard Silver Nitrate.—Dissolve about five grams  of
pure recrystallized silver  nitrate in distilled water,  and
make the solution up to iooo c.c. The amount of chlorin
to which this is equivalent may be determined as follows :
Several grams of pure sodium chlorid are finely powdered
and heated over a Bunsen burner for five minutes, not quite
to redness.  When cold, 0.824 gram are dissolved in water
and the solution made up to 500 c.c.   Twenty-five c.c.  of
this should be treated as below, and  the  amount of silver
solution required noted.   Each c.c. of the sodium chlorid
solution is equivalent to 0.001 gram chlorin.
  Potassium  Chromate.—Five  grams of potassium chro-
mate are dissolved in 100 c.c. of distilled water.   A solu-
tion of silver nitrate  is added until a permanent red  pre-
cipitate is produced, which is separated  by filtration.
Analytic Process :
  If a preliminary test shows the chlorin to be present  in
considerable amount, the determination may be made on
100  c.c.  of the water without  concentration.  If, how-
ever, there is but little  present, 250  c.c. should be evap-
orated to about one-fifth, best with the addition of a little
sodium  carbonate, and the determination  made  on the
concentrated liquid after cooling.
  The water is  placed  in  a  porcelain dish or in a beaker
standing on a  white  surface,  a  few drops of potassium
chromate solution added, and standard silver nitrate solu- 
SANITARY  EXAMINATIONS.
33
tion  run in from a buret until a faint red color  of silver
chromate remains permanent on stirring.  The proportion
of chlorin is  then calculated  from  the  number of c.c.
of silver solution added.   For greater accuracy  a second
determination  may be  made, using as a comparison  the
liquid first titrated, the  red  color having  been previously
discharged by  a few drops of sodium  chlorid solution.
  The water should always be as nearly neutral as possible
before titration.   If acid,  it may be neutralized by  the
addition  of  sodium  carbonate.    Greater  accuracy is
secured by operating in yellow  light.
  The  residue obtained by evaporating the water with
sodium  carbonate, as described  in connection with the  de-
termination  of the total solids, will  often serve  conveni-
ently for estimating the  chlorin.  It is best to use 200 c.c.
of the sample and redissolve the residue in about 50 c.c.
of distilled water, rubbing the sides  of the dish well with a
rubber-tipped  ro'd, and  then titrating as indicated above.


   NITROGEN IN AMMONIUM COMPOUNDS AND IN
                  ORGANIC MATTER.
Apparatus Required:
  Distilling Apparatus.—That  shown in figure 3  has been
found  to  be the most convenient.   The still consists of a
Bohemian glass retort of about  1000 c.c. capacity.   The
beak of the retort should incline slightly upward, to pre-
vent contamination by splashing.   At about seven centi-
meters from the end it should be bent at a right angle, and
drawn out so as to enter the condensing worm  for such a
distance as to  terminate beneath the level of the water.
       c 
34              ANALYTIC OPERATIONS.
  The condenser shown  in  the figure is  a copper tank,
33 centimeters  high, 15 centimeters wide, and of length
proportioned to the number of distilling vessels operated.
The condensing tube is shown only as emerging from the
bottom of the tank.
                        Fig. 3.

  Glass worms  are apt to crack, and it  is more satisfac-
tory to use block tin.  A piece of rubber tubing is  drawn
over the junction between the  retort neck and worm    A
rapid current of cold water should be maintained through
the  condenser.  The heat is applied by means of the low-
temperature burner, the iron  ring of which is  removed so 
SANITARY EXAMINATIONS.
that the retort rests  directly on the gauze.   With this
arrangement the  heat is  under  perfect control, and the
Scale \Y. in.= 1 foot.
   Fig. 4.
danger of fracturing the glass is  reduced  to  a minimum.
It is advisable  to  protect the  retort from drafts of cold 
36              ANALYTIC OPERATIONS.

  Another  convenient form of apparatus is shown in figure
4.   It is employed in the  laboratory of the Massachusetts
State Board of Health.   The joint between the flask and
condenser is made  by means of a sound cork, into which
the condensing  tube fits closely;  the tube from the  flask
                     is  made slightly smaller  than the
                     condensing tube, and passes into it
                     for about four centimeters.
                        A form of condenser applicable
                     to distillations of this character has
                     been devised by Cribb and is shown
                     in figure 5.   The vapor passes into
                     narrow annulus by the  tube A ; the
                     cooling  water  enters  the central
                     portion  and  overflows,  running
                     down  the outside  wall, being col-
                     lected by the projecting rim and
                     carried  off by the  tube  G.   For
                     water  analysis  a  retort  with the
                     neck bent at an obtuse angle may
                     be used, or  a flask with side  tube.
                     In the latter case,  the  tube  must
                     leave  the flask at a  slight  angle
                     upward, and about midway be bent
 at  a slight obtuse angle  downward.   This prevents con-
 tamination of the  distillate by spurting.
    Cylinders for Comparison-color  Tests,  about  2.5 centi-
 meter in diameter and holding 100 c.c,  made of colorless
 glass.
 Solutions Required :
    Sodium  Carbonate.—Fifty  grams of pure sodium carbon-
Fig. 5. 
SANITARY  EXAMINATIONS.
37
ate are strongly heated, dissolved in 250 c.c. of distilled
water, and the solution boiled down to 200 c.c.
   Ammonium-free  Water.—If  the  distilled  water of the
laboratory gives a reaction with Nessler reagent, it should
be treated with sodium carbonate, about one grain to the
liter,  and boiled until about one-fourth has been evapor-
ated.   Ammonium-free water may be obtained by distill-
ing, in a retort, water made slightly acid with sulfuric acid.
   Standard Ammonium Chlorid.—Dissolve 0.382 gram of
pure  dry ammonium  chlorid in 100 c.c. of ammonium-
free  water.   For  use, dilute 1  c.c. of this  solution with
pure  water to 100 c.c.  One c.c. of this dilute solution con-
tains  0.00001 gram of nitrogen.
   Nessler Reagent.—Dissolve 35 grams of potassium iodid
in 100 c.c. of water.  Dissolve  17 parts of mercuric chlorid
in 300  c.c  of water.  The  liquids  may  be
heated  to aid solution, but  must  be cooled
before use.   Add  the mercuric chlorid solution
to that of the potassium iodid, until a perma-
nent  precipitate  is  produced.  Then dilute
with  a  20  per cent,  solution of  sodium  hy-
droxid  to  1000  c.c, add mercuric chlorid
solution  until a  permanent precipitate  again
forms, and allow to stand  until clear.  Nessler
and  other reagents are  best kept in glass-capped bottles,
figure 6, in which the pipet may remain when not in use.
The solution improves by keeping.
   Alkaline Potassium  Permanganate.—Dissolve 200 grams
of potassium hydroxid, in sticks,  and 8 grams of potas-
sium  permangajiate, in a liter of distilled water.
   The solution may be boiled until about one-fourth  is
 
3«
ANALYTIC  OPERATIONS.
 evaporated, and then made up to a liter with ammonium-
 free water.   It will still furnish some ammonium.   Fox
 recommends to distil 50 c.c. with  500 c.c. of absolutely
 ammonium-free water,  best twice distilled with  sulfuric
 acid, and  note the  ammonia  obtained.   This quantity
 should be deducted in each analysis.  The method of de-
 termining nitrogen by permanganate,  as recommended by
 the A. A. A. S., avoids the  necessity  for this preliminary
 valuation of  the solution.
 Analytic  Process:
   The retort and condenser are thoroughly rinsed with
 ammonium-free water, 500 c.c of the water to  be tested
 introduced, about  five c.c. of the sodium  carbonate solu-
 tion added to render the water  alkaline, and some small
 pieces of pumice-stone or  fragments of pipe-stems  heated
 to redness and dropped in while  hot.   The water is then
 boiled gently until the distillate measures 50 c.c.   The
 distillate is transferred  to  one  of the color-comparison
 cylinders, and two c.c of Nessler reagent  added.   A yel-
 lowish-brown color is produced, the intensity of which  is
 proportional to the amount  of ammonium  present.  The
 full color is developed in five minutes.  This color is ex-
 actly matched  by introducing  into another cylinder 50
 c.c  of ammonium-free  water, some of the standard am-
 monium  chlorid solution, and two c.c. Nessler reagent,
as before.   According as the color so produced is  deeper
 or lighter than that obtained from  the water, other com-
parison liquids are prepared  containing smaller or larger
proportions of  the ammonium chlorid, until  the  proper
color is produced.
  The distillation is continued, successive  portions of 50 
SANITARY  EXAMINATIONS.
39
c.c.  each collected,  and tested  until no  reaction occurs
with Nessler reagent.   The sum  of the figures  from the
several  distillates  gives  the total  nitrogen  obtainable as
" free ammonia," so called.
  If the quantity of ammonium is sufficient to cause a
precipitate, the  color comparison  can not  be accurately
made.   In most cases this will not be of serious moment,
as the quantity will  be beyond the allowable limit.  If
accurate determination be desired, it may be  made by
dividing the first distillate into two equal  parts, nessleriz-
ing  one of these,  and  then,  if necessary,  diluting the
second  part with ammonium-free  water  and  nesslerizing
this.
  Occasionally, the evolution of ammonium hydroxid con-
tinues indefinitely, and may even increase with successive
distillates.  This  is  due,  not  to ammonium compounds
existing as such, but to  decomposition of  certain nitro-
genous  bodies,  especially urea.    In this case it is not
advisable to prolong  distillation beyond the fourth or fifth
distillate, but to proceed to  the  following  part of the
process.
  The residue in the retort serves for the determination
of  the  nitrogen which is  convertible into ammonium by
alkaline potassium permanganate—the  so-called  "albu-
minoid ammonia"  of Messrs. Wanklyn, Chapman, and
Smith.
   Fifty c.c. of  alkaline permanganate solution are added
to  the  retort, the  distillation  resumed, and the nitrogen
estimated in  each 50 c.c. as before, deducting that yielded
by  the  permanganate.
   It is  the practice of some analysts  to mix the distillates 
40              ANALYTIC OPERATIONS.

of each of  the  foregoing  operations, and  make  deter-
minations merely of the  total nitrogen in each case.   By
so doing, valuable information may be  lost, since  it has
been pointed out by several observers, notably Mallet and
Smart,  that  important  information may be  gained  by
observing the rate of evolution of the ammonium hydroxid.
Mallet has further pointed out that many waters may con-
tain  substitution ammoniums which may.pass  over before
the addition of the alkaline permanganate, but not be cor-
rectly measured by nesslerizing.   To avoid  this source of
error, he suggested that  two determinations be made on
each sample, one as above described, and the other by the
addition of alkaline permanganate without previous dis-
tillation.  In this manner a higher figure  will often be
obtained than the sum of the figures from the two distilla-
tions by the other process.
   Since small quantities of ammonium compounds and
nitrogenous matters are  everywhere present, the greatest
care should  be exercised in order to avoid their introduc-
tion in any way during  the  course of the  analysis.   All
measuring  vessels, cylinders,  etc.,  should  be thoroughly
rinsed before using.   The temperatures of  the  distillates
and  standards should be approximately the same when the
colors are compared.
   The  Chemical Section of  the American Association for
the  Advancement of Science recommends  the following
method for  the application of the process, embodying the
results of recent investigations :
   "Two hundred c.c. of distilled water, together with 10
c.c.  of the  sodium carbonate solution, are distilled down
to about ioo c.c in the  retort in which  the analysis is to 
SANITARY  EXAMINATIONS.
41
be conducted, and the last  portion of 50 c.c. nesslerized
to assure freedom from ammonium.   Then 500 c.c. of the
water to be examined are added, and  the distillation  is
carried  on at  such a rate that about 50 c.c. are collected
in each  succeeding ten minutes, and until a 50 c.c meas-
ure of distillate is obtained  containing only an  inappre-
ciable quantity of ammonia.   In nesslerizing, five minutes
are to be allowed for the full development of color; after
this, no change takes place for many hours.
   "Now throw out the  contents of the  retort, rinse  it
thoroughly, put in 200 c.c. of distilled water and 50 c.c.
of the permanganate solution, distil down to  about 100
c.c, and nesslerize the  last  portion of 50  c.c,  to  make
sure of  freedom from ammonia; add another  portion  of
500 c.c. of the water under examination, and proceed with
the distillation and  nesslerizing as with the first  portion.
   "The difference between the 'free' ammonia of the
first operation and the total ammonia of  the second is  to
be taken as the 'albuminoid' ammonia."
   Bachman  has  described  a  process  for determining
nitrogen by permanganate by using an apparatus which
permits of the addition of the water in  small and limited
quantity to the full strength of permanganate  solution  at
about the rate of distillation, so that  at no time does it act
upon a large volume.   The apparatus consists of a flask  of
one liter capacity, fitted  by a ground joint to a hollow cap
carrying two  upright tubes, each provided with a stop-
cock, and  to which cap also is attached the tube through
which the distilled vapors pass to the condenser.   Of the
two upright tubes, one  has a  capacity of 50 c.c, and  its
end reaches through the cap to within three inches of the 
42
ANALYTIC OPERATIONS.
bottom of the distillation flask.  The other has a capacity
of 250 c.c, and its  tube  projects to within one-half of
the bottom.  The condensing apparatus is a closely-coiled
glass worm, with a long projection at the lower  extremity
which passes through a soft rubber  cork, inserted in  a
receiver.    Through this cork also there is  connected  a
Will and Varrentrap amin-absorption bulb.  All connec-
tions should be tight,  without the use of a lubricant.   The
arrangement can be made movable, so as to be raised from
the bath if necessary.  Bachman  employs a bath of  salt
water, but  it is not unlikely that a low-temperature burner
would answer every purpose.
  The procedure is as follows:  After thoroughly rinsing
the apparatus with ammonium-free distilled water, 500 c.c.
of the water under examination,  with  the addition of  a
little sodium carbonate if  needed, are put into the flask.
The  Will  and Varrentrap bulb  is charged  with Nessler
solution, and the  free  end  of the bulb connected with an
exhaustion   apparatus.  A  partial vacuum is established
gradually,  and the  distillation carried on until  200 c.c.
have passed over.  The vacuum-tube is disengaged, and
250  c.c. of the liquid in  the distilling flask drawn into
the larger  upright tube, and 50 c.c. of alkaline perman-
ganate solution which has  been previously placed  in  the
small tube, allowed to run  in, after the flask to receive the
distillate has been again attached.  This arrangement gives
50 c.c.  of  alkaline permanganate acting on  50 c.c. of
water, and after 30 or 40 c.c. have been distilled over the
water in the larger tube is allowed to drop in at the same
rate as the  distillation, which must  not  exceed 50 c.c. in 
SANITARY  EXAMINATIONS.
43
fifteen minutes.  This is continued  until from 250 to 300
c.c. have been distilled over, which is then nesslerized.
   For nesslerizing and other color comparisons,
many forms of apparatus have been proposed.     f^
One of the simplest is that devised by Hehner,      Z
shown in figure 7.   It consists of a graduated      '.*„
cylinder with a  stop-cock near the base, by      '"
which the liquid can be drawn down at will.
Two  such cylinders may be used—one for the
nesslerized distillate, the  other for the  com-
parison liquid.   The darker liquid  is  drawn
out until the tints are equal, when the relative
volumes  remaining  will  give the  data for  calculation.

             TOTAL ORGANIC NITROGEN.
   Several processes for  the determination of the  organic
nitrogen in water, based on those in use in ordinary organic
analysis, have been devised.  That of Frankland and Arm-
strong requires complex  and extensive apparatus and spe-
cial skill, has been shown also to be  liable to inaccuracies,
and has not come into extended use.
   The ease and certainty with which the nitrogen of most
organic bodies may be converted into ammonium  sulfate
by boiling with sulfuric acid, offers a means of determina-
tion free  from the  objections of  former methods.   The
method introduced by Kjeldahl for general organic analy-
sis was first successfully applied to water analysis by Drown
and Martin.
   In their original process, 500 c.c. was concentrated  to
about 300 c.c, and the distillate nesslerized for determin-
ing the nitrogen existing as ammonium compounds.   The 
44
ANALYTIC OPERATIONS.
organic nitrogen is then determined in the residual water.
Owing to the fact that in many waters the organic  matter
is  decomposed by  boiling, there is liability to under-
estimation of the nitrogen.  It  is best, therefore,  to deter-
mine at once the total unoxidized nitrogen, and estimate,
without distillation, on a separate portion of the sample,
the nitrogen that  exists in ammonium compounds.   The
procedure is as follows :
Reagents Required :
   Concentrated Sulfuric  Acid.—This should be as  free as
possible from  nitrogen.    It can  be  obtained  containing
only 0.015 milligram in  10 c.c.
   Sodium Hydroxid Solution.—The white  granulated caus-
tic soda sold for household use will answer  ; 350 grams are
dissolved in water and made up to 1000 c.c.
   Sodium Carbonate and Hydroxid Solution.—Twenty-five
grams of each are dissolved in  250 c.c. of distilled water,
and the solution  boiled  down  to 200 c.c to free it from
ammonium.
Analytic Process :
   Determination of Nitrogen Existing as Ammonium.—Two
hundred c.c.  of the  water are placed in a stoppered  bottle,
two c.c. each of  the solutions of sodium carbonate and
sodium  hydroxid added, the stopper inserted, the  solutions
mixed, and allowed to stand for an hour or two.   A filter
is  prepared by inserting a rather large plug  of absorbent
cotton in a funnel.   This should be washed with ammo-
nium-free water until the filtrate gives no color with Nessler
reagent.  The clear portion of the sample  is drawn off
with a pipet  and  run through   the filter, the first  portions
being rejected, since it  is diluted by the water retained 
SANITARY  EXAMINATIONS.
45
in the  cotton.   The  filtration  is rapid, and  when  ioo
c.c.  of  the  liquid have  passed  through it, is nesslerized.
If but  little ammonium  is present, a narrow  tube about
60 centimeters long should be used for observing the color.
  Estimation of the  Total Organic and Ammoniacal Nitro-
gen.—Five hundred  c.c. of the water are placed in a round-
bottomed Bohemian glass flask, ten c.c. of concentrated
sulfuric  acid  added,  and  a  piece  of  pumice-stone is
heated to bright redness and dropped  in while hot.  The
liquid is boiled until the acid is colorless or very pale, the
boiling being continued for nearly an hour from this point.
The flask is then  removed from the flame, allowed to cool,
and  about 250 c.c of ammonium-free water added. Fifty
c.c.  of  the sodium hydroxid solution should  be placed in
the distilling apparatus, figure 3, about  250  c.c. of water
added, a piece of red-hot pumice-stone dropped in, and the
liquid distilled until the distillate  is free from ammonium.
It is best to distil until the retort contains not more than
100  c.c.   The sulfuric  acid solution  is  then poured in
slowly by means of a funnel, the stem  of which touches
the side of the retort, so that the two liquids do not mingle.
The stopper of the retort is inserted, the liquids mixed by
gentle agitation,  and distilled.   If  much ammonium is
present, it is advisable to distil the first portion into about
ten c.c. of  very  dilute  (1 : 1000)  sulfuric  acid, a piece
of glass tube being connected to the condensing worm so
that the lower end  dips below the  surface of the liquid.
The distillates are collected  and nesslerized in the usual
way.
  A blank experiment should be  made  to determine the
amount of ammonium in the sulfuric acid. 
46
ANALYTIC  OPERATIONS.
              NITROGEN  AS NITRATES.
Solutions Required:
  A. H. Gill has subjected the various  indirect methods
of estimating nitrates  to  comparative examination,  and
finds the following method  satisfactory :
  Phenoldisulfonic Acid.—Strong  sulfuric  acid  and pure
phenol are mixed  in  the  proportion  of 37 grams of the
former to 3 grams of  the latter, and  heated for six hours
in,  not  upon, the  water-bath.  The  resulting compound
usually solidifies to a  white mass on standing, but can be
easily liquefied  on the water-bath  during the evaporation
of the samples to be tested.
  Standard Potassium Nitrate.—0.722 gram of potassium
nitrate,  previously heated  to  a temperature just sufficient
to fuse it, are dissolved in water, and the solution made up
to 1000 c.c.  One c.c. of this solution will contain 0.0001
gram of nitrogen.
Analytic Process :
  A measured volume of the water is evaporated just to dry-
ness in a porcelain basin about six centimeters in  diameter.
One c.c of the  phenoldisulfonic acid is added  and thor-
oughly mixed with the residue by means of a glass rod.
The liquid is then diluted with about 25 c.c.  of water,
ammonium hydroxid  added  in  excess,  and  the solution
made up to 50 c.c.
  The  nitrate  converts the  phenoldisulfonic  acid  into
picric  acid,  which,  by the  action  of  the  ammonium
hydroxid,  forms  ammonium  picrate ; this imparts to the
solution a yellow color, the intensity  of which is  propor
tional to the amount present. 
SANITARY  EXAMINATIONS.              47
  One c.c. of the standard solution  of potassium nitrate
is now similarly evaporated in a platinum basin, treated as
above, and made  up to 50 c.c.   The  color  produced is
compared to  that given by the water, and one or the other
of the solutions is diluted until the tints of the two agree.
The comparative volumes of the liquids furnish the neces-
sary data for  determining the amount of nitrate.
  Mr. Gill has furnished me with an account of the method
pursued at the  Massachusetts Institute  of Technology for
obtaining a comparison liquid.   Ten c.c.  of the standard
nitrate solution are cautiously evaporated, spontaneously or
in  a desiccator, and  three  c.c. of  the phenoldisulfonic
acid  added,  the  mixture -diluted  with water to  exactly
1000 c.c.   Of  this solution,  portions  are measured out
with  a finely and  accurately graduated  pipet into the por-
celain dish  similar to  that in which the water-sample
has been evaporated, water added to make exactly 10 c.c,
and then two or three drops of ammonium  hydroxid to
make the liquid  alkaline.   The quantity of liquid taken in
the pipet  has the following values in parts per million of
nitrogen as nitrates : 10 c.c. — 1.0 ;  5  c.c. = 0.5 ; 2  c.c.
= 0.2; 0.5  c.c. =0.05.  Comparison  is thus  made di-
rectly in the dishes.  In case of doubt, the liquids are com-
pared in tubes similar  to nesslerizing tubes, but  cut down
to hold 15 or 20 c.c.
  The results obtained  by this  method are  satisfactory.
Care should be taken that the same quantities of phenoldi-
sulfonic acid  are used for the water and for  the  compari-
son liquid.
  With subsoil and other waters probably containing much
nitrates, 10 c.c.  will be sufficient; but with river and spring 
48
ANALYTIC OPERATIONS.
waters,  25 c.c may be used.   When the organic matter is
sufficient to color the residue, it will be well to purify the
water by addition of aluminum hydroxid and filtration,
before evaporating.
   Chlorin interferes  with the accuracy of the test, but Gill
finds that when not amounting  to more than  20 parts per
million  it does not impair the practical value of the results.
When  greater than  this, it is  best to evaporate in vacuo
over sulfuric acid.   If the chlorin be more than  70 parts
per  million, it  should  be considerably reduced by  the
addition of silver  sulfate  which  has been ascertained
to be free  from  nitrates.  Nitrites do not  influence the
reaction.
   The following is the process for determining nitrogen as
nitrates (and nitrites) recommended by the Chemical Sec-
tion of the A.  A. A.  S.   It depends upon conversion into
ammonium  by the copper-zinc  couple, and subsequent
nesslerizing.   It  is inferior to the phenoldisulfonic  acid
method, both  in  convenience and accuracy,  and does not
exclude the influence of nitrites.
   Take two wide-mouth glass-stoppered bottles, each hold-
ing 250 c.c, and  a piece of sheet zinc as long and about as
wide as  the bottles are deep from the shoulder down ; clean
the zinc by dipping in dilute  acid and washing with water,
and make it into a loose coil by rolling it around a piece of
glass tube.   Immerse it in a 1.4 to 1.8 per cent,  solution
of copper sulfate in ammonium-free  water,  and  leave  it
there  until  its  surface  is  well covered  with a continuous
layer of the black copper;  lift it  out  carefully, cover  it
in a  beaker with successive  portions  of  ammonium-free
water, lifting it out  and draining each time, and at once 
SANITARY  EXAMINATIONS.
49
 put it into one of the bottles of acidified water, prepared
 as follows :
   Make 500 c.c. of the water to be examined distinctly
 acid with oxalic acid added in fine powder, with constant
 stirring, so that it shall dissolve readily,  and pour half of
 the liquid into one of these 250 c.c. bottles, and half into
 the other, and leave them, stoppered, in  a warm place for
 twenty-four hours.  Then nesslerize both samples, decant-
 ing off the portions, as wanted, from the precipitated earthy
 Oxalates,  and using double the usual quantity of Nessler's
 solution,  since the free oxalic acid  must be  neutralized
 first by the alkali of the reagent.   The proportion of am-
 monia may often be  so  large in the water in which the
 reduction is  made, by the  copper-zinc couple, that  only
 five or ten c.c. can be taken  for each  test, and made up
 to 50 c.c. by the addition of  ammonium-free water.  The
 difference between  the  results  with  the  two portions  of
 water  gives the amount of  nitrogen due  to the oxidized
 nitrogen compounds in the water examined.

               NITROGEN  AS NITRITES.
  The following  is Ilosvay's modification  of Griess's test.
 It has the advantage over the original method, that the
 color  is developed more rapidly, and the solutions are less
 liable to change.
 Solutions Required :
  1 -4-amidobenzenesulfonic Acid Solution (Sulfanilic Acid).
 —Dissolve 0.5 gram in 150 c.c.  of diluted  acetic acid,
 sp. gr. 1.04.
  a-amidonaphthalene Acetate  Solution.—Boil  0.1 gram of
solid  a-amidonaphthalene  (a-naphthvlamin)  in  20  c.c.
       D 
50               ANALYTIC OPERATIONS.

of water, filter the solution through a plug of washed absor-
bent cotton, and mix the filtrate with  180 c.c. of diluted
acetic acid.  All water used must be free from nitrites, and
all  vessels  must  be rinsed out with such water before tests
are applied, since appreciable quantities  of nitrites may
be taken up from the air.
  Standard Sodium Nitrite.—o. 275 gram pure silver nitrite
are dissolved in  pure water, and  a dilute solution  of pure
sodium chlorid added until the precipitate ceases to  form.
It is  then  diluted with pure water to 250  c.c,  and al-*
lowed to stand until clear.  For  use  10 c.c.  of this solu-
tion are diluted  to 100  c.c.   It  is to be kept in the dark.
One c.c. of the  dilute solution  is  equivalent to 0.00001
gram nitrogen.
  The silver nitrite is prepared thus :  A hot  concentrated
solution of silver nitrate is added to a concentrated solu-
tion of the purest sodium or potassium  nitrite available,
filtered while hot,  and allowed to cool.  The silver nitrite
will separate  in  fine,  needle-like  crystals, which are freed
from the mother liquor by filtration by the aid of a filter
pump.   The crystals are dissolved in the smallest possible
quantity of hot water, allowed to cool, and again separated
by means of the pump.   They are  then thoroughly dried
in the water-bath, and  preserved in  a tightly stoppered
bottle away from the light.   The purity may be tested by
heating  a weighed quantity to redness in a tared porcelain
crucible  and  noting the weight of the  metallic silver.
One hundred and fifty-four parts  should leave a residue  of
108 parts silver.
Analytic  Process :
  Twenty-five c.c. of the water  are placed in one of the 
SANITARY  EXAMINATIONS.
51
color-comparison cylinders, and two c.c. each  of the test
solutions are dropped in.  It is convenient to have a pipet
for each solution, and to use it for no other purpose.
   One c.c.  of the  standard nitrite solution is placed in
another clean  cylinder, made up with nitrite-free water to
25 c.c. and  treated  with the reagents as above.
   In the presence of nitrites a pink color is produced.  At
the end of five minutes the  two solutions are  compared,
the colors equalized by  diluting the darker, and the calcu-
lation made as explained under the estimation of nitrates.
   The reactions consist in the conversion  of the sulfanilic
acid into diazobenzenesulfonic anhydrid, by  the  nitrite
present; this  compound is then in turn converted  by the
amidonaphthalene  into  azo-a-amidonaphthalene-i-4-ben-
zenesulfonic acid.  The last-named body gives the color
to the liquid.

             OXYGEN-CONSUMING POWER.
   All organic materials being more or less easily oxidized,
several methods have been  suggested  for determining the
oxygen-consuming  powers  of waters  by  treatment with
active  oxidizing  agents.   These  methods are, however,
limited in value.   The organic matters  in water  differ
much in character and condition,  and their oxidability is
subject to much variation, according to the circumstances
under  which the test  is made.   Nevertheless, as a high
oxygen-consuming power certainly indicates departure from
purity, some additional evidence may be obtained.   Potas-
sium  permanganate is  especially suitable.   The  test  is
usually made by introducing a known amount of the per-
manganate into the water, which has  been rendered acid, 
52               ANALYTIC OPERATIONS.

and measuring after a definite period the proportion which
has been decomposed.
  It must  not be overlooked that if a  water  contains
nitrites,  ferrous  compounds,  or sulfur compounds  other
than sulfates, the proportion of oxygen consumed will be
greater than that  required for the organic  matter.   It  has
been  proposed,  in order to  remove  the  nitrites  before
applying the permanganate, to take 500 c.c. of the water,
add  10 c.c. of  the  dilute sulfuric acid,  boil  for twenty
minutes, allow to cool, and then treat with permanganate.
Since, however, the amount of nitrites, if appreciable, can
be directly determined,  it is  more  satisfactory to deduct
from the oxygen consumed the amount required to con-
vert the nitrites present into  nitrates, and the remainder
will be that required for the other oxidizable ingredients.
Fourteen parts of nitrogen existing as nitrite require 16
parts  of oxygen  for conversion into nitrate.  Similarly,
112  parts of iron in a ferrous compound will require 16
parts of oxygen for conversion to the ferric condition.
  Of the following methods the first is due, in the main,
to Dr. Tidy, has been improved  by Dr. Dupre, and is
approved  by the  Society of Public Analysts of Great
Britain :
Solutions Required:
  Standard Permanganate.—0.395 gram  pure potassium
permanganate  are dissolved  in distilled water,  and  the
solution  made up to 1000 c.c.   One c.c. is equal to
0.0001 gram oxygen.
  Diluted Sulfuric Acid.—Add 50  c.c.  of pure  sulfuric
acid  to 100 c.c. of water, and then add solution of potas-
sium permanganate until a faint  pink color is obtained, 
SANITARY EXAMINATIONS.
53
which is permanent when the liquid  is heated to 8o° F.
for four hours.
  Potassium Iodid.—Ten grams of the pure salt recrystal-
lized from alcohol are dissolved  in  ioo c.c. of distilled
water.
  Sodium Thiosulfate.—One gram of the pure crystallized
salt dissolved in 2000 c.c. of distilled water.
  Starch  Bidicator.—One gram of clean starch is mixed
smoothly  with cold water into  a thin paste, then poured
gradually  into about 200 c.c. of boiling water,  the boiling
continued for one minute, the liquid allowed to settle, and
the clear portion used.   It is best freshly prepared.
Analytic Process:
  Two  determinations are made—one, of the oxygen con-
sumed in  fifteen minutes, which is considered to represent
the nitrites, sulfids, or ferrous compounds, and the other,
of the oxygen consumed by  four hours' action.   Both de-
terminations are made at a temperature of 8o° F.  Three
glass-stoppered  bottles,  of  about 350 c.c.  capacity, are
rinsed with strong sulfuric acid and  then with water.   In
one is placed 250 c.c.  of pure distilled water as a control
experiment, and in each of the others 250 c.c. of the water
to be tested.  The bottles are stoppered and brought to a
temperature of 8o°  F.;  10 c.c. of the dilute sulfuric acid
and  10  c c. of the  standard permanganate  are added to
each, and the  stoppers again replaced.  At  the end of
fifteen  minutes  one sample of water is removed from the
bath, and two or three drops of the  potassium iodid solu-
tion added to  remove  the  pink color.   After thorough
admixture, the thiosulfate solution is  run in from a buret
until the yellow color  is nearly destroyed, a few drops of 
54              ANALYTIC OPERATIONS.

the starch solution  added, and the addition of  the thiosul-
fate continued  until the blue color  is quite  discharged.
If the addition of  the thiosulfate  solution   has   been
properly conducted, one drop of the permanganate solution
will restore the blue color.
  The other bottles are maintained at  8o°  F. for four
hours.   Should the pink color disappear rapidly in the
bottle containing the water under examination, 10 c.c. of
the permanganate solution  must be added to each bottle,
in order to maintain a distinct pink color.  At the end of
four hours  each bottle is  removed  from the bath, two
or three  drops of potassium  iodid added,  and the titra-
tion with  thiosulfate solution conducted as just described.
The calculation is most conveniently  made as follows:
  a = number of c.c. required for the control experiment.
  b = number of c.c. required for the water under exam-
    ination.
  c = available O in permanganate (o.ooi for 10 c.c).
  x = oxygen consumed by water.
  Then, a : a—b :  : c :  x.

  The following method is  recommended by the Chemical
Section of the American Association  for the Advancement
of Science :
  "Prepare a  solution  of  potassium permanganate  con-
taining 0.2 milligram of available oxygen to i c.c. and a
solution of oxalic acid of such strength as to decompose
the permanganate solution, volume for volume, the strength
being redetermined from time to  time.   The water used
for making these solutions should be purified by distillation
from alkaline permanganate. 
SANITARY  EXAMINATIONS.              55
   "To 200 c.c.  of  water  to  be examined, in a 400 c.c
flask, add 10 c.c. of dilute sulfuric  acid (1 : 3) and such
measured quantity of the permanganate as will give a per-
sistent color; boil ten minutes, add, if necessary,  more
permanganate in measured  quantities, so as to maintain the
red color ;  remove the  flask from the lamp, add  10 c.c.  of
oxalic  acid  solution to destroy the  color, or more if re-
quired by the excess of permanganate, and then add per-
manganate, drop by drop,  until a faint  pink tint appears.
From the total quantity of permanganate used deduct the
equivalent of the oxalic acid used, and from the remainder
calculate the milligrams of oxygen consumed by the oxid-
izable organic matter in the water."
   The oxygen-consuming  power may  also be  indirectly
estimated by the action of the organic matter upon silver
compounds.   H. Fleck's method depends upon the reduc-
tion produced by boiling the water with alkaline solution
of silver thiosulfate and estimation of the unreduced silver.
A.  R.  Leeds has proposed a method by treating the water
with decinormal  silver nitrate, exposing to light until it
settles perfectly clear, and  estimating the reduced silver.
   These methods are  open to practically the same objec-
tions as in  the use of permanganate, and do not seem  to
possess any  decided  advantage.  Qualitative  results  of
some  interest may occasionally  be  obtained by the fol-
lowing method :  Two  c.c.  of a one per cent, solution of
silver nitrate, rendered decidedly alkaline by ammonium
hydroxid, are added to 100 c.c of the water in a stop-
pered bottle, which  is  then placed in full  sunlight for two
hours.   Waters containing but little organic matter will
not show at the end  of  this period any appreciable tint. 
56
ANALYTIC  OPERATIONS.
                    PHOSPHATES.
Solution Required:
  Weigh into a beaker 10 grams of pure molybdenum ter-
oxid, mix well with 40  c.c. cold distilled water, and add
8 c.c. strong ammonium hydroxid, sp.  gr.  0.900.  When
completely dissolved, filter and pour slowly, with constant
stirring, into a mixture of 40  c.c. of nitric acid, sp. gr.
1.42, and  60 c.c.  of  water.   Add 0.005  gram sodium
ammonium  hydrogen  phosphate,  dissolved in  a  little
water, agitate well,  allow precipitate to settle twenty-four
hours, and filter before using.
Analytic Process:
  Five hundred c.c. of the water are slightly acidified with
nitric acid, and evaporated to about 50 c.c.  A few drops
of dilute  solution of ferric chlorid are added and  then
ammonium  hydroxid  in slight excess.  The precipitate,
which contains all  the  phosphate,  is filtered off and dis-
solved on the filter by the smallest possible quantity of
hot dilute  nitric  acid.  The filtrate and washings should
not exceed five c.c;  if more, they must be evaporated to
this bulk.   The liquid is heated nearly to boiling, two c.c.
of ammonium molybdate solution  added, and  the liquid
kept moderately warm for half an hour.  If the quantity
of precipitate is  appreciable, it  is collected on  a small
weighed  filter, washed with distilled water, dried at  1000
F., and weighed.   The weight of the precipitate multiplied
by 0.05 gives the amount of P04.  If the quantity is not
sufficient to  collect in this manner, it is usually reported,
according to circumstances, as "traces," " heavy traces,"
or "very heavy traces." 
SANITARY  EXAMINATIONS.
57
                 DISSOLVED OXYGEN.
  The method  here  given, a modification of Mohr's, was
proposed by Blarez.   It is rapid and satisfactory.
Solutions Required :
  Sodium Hydroxid.—Forty grams of pure sodium hy-
droxid to the liter.
  Ferrous-ammonium Sulfate.—Forty grams dissolved in
about a liter of water, and  acidified with a  few drops of
concentrated sulfuric acid.
  DecinormalPotassium Permanganate.—3.156 grams dis-
solved  in  a liter of distilled water.    The
accuracy of this solution should be  determined
by  titration with a  known  weight  of  ferrous-
ammonium sulfate.   One c.c. should be equiv-
alent to 0.0392 gram  ferrous ammonium sulfate
(0.0008 gram of oxygen).
  The apparatus employed (shown in Fig.  8)
is  a  globular  separator,  of  about 250 c.c.
capacity.  Above the bulb is a  caoutchouc
stopper carrying a cylindric funnel, of about
12  c.c.  capacity,  terminating in  a tube,  8
mm. caliber, sharply contracted at the  outlet
to a capillary opening.  The tube  should pro-    fig. 8.
ject about 6  mm.   below  the  stopper.   The
exact capacity of the apparatus is measured as  follows:
The bulb is completely filled with water and the stopper
inserted ; the level  of the water will  rise slightly in  the
funnel tube, and should be brought down  to its outlet by
drawing a little off at the stop-cock, after which the water
is run  into a graduated measure and its volume noted.
 
58
ANALYTIC  OPERATIONS.
Analytic Process:
  Thirty-five c.c.  of  mercury and  ten c.c.  of sodium
hydroxid solution are put into the bulb, and then sufficient
of the water to  be tested to fill it.  The funnel stopper is
inserted, and the water which rises into the funnel brought
into the bulb by cautiously running  out at the stop-cock,
mercury, the volume of which  should be noted.   The
exact volume of water used is thus known.   Five c.c. of
the ferrous ammonium  sulfate  solution  are  poured into
the funnel, brought  into the bulb by running out mercury,
and the liquid thoroughly mixed by  giving the apparatus
a gyratory movement.   After standing five or six minutes,
the oxygen will be completely absorbed; 10  c.c. of the
diluted  sulfuric acid are now added  by the same method.
On agitating the bulb, the contents  become  clear.   The
watery liquid is then  transferred to a beaker  and titrated
with decinormal permanganate.   A volume of water equal
to that  used in the test is poured into another beaker,
10 c.c.  each of  the sodium hydroxid  and  diluted  sul-
furic  acid added, and  then 5 c.c. of ferrous ammonium
sulfate solution.   The resulting liquid is  titrated  with
permanganate.   The weight of oxygen  corresponding to
the difference between the  two titrations gives the weight
of dissolved oxygen in the liquid employed.
  Nitrates do not appear to impair  the accuracy of this
method, and the  interfering action  of nitrites and  other
reducing compounds is avoided by the control experiment.
  It is perhaps hardly necessary to add that the exact tem-
perature of the  water is to be noted at the time of collec-
tion of the sample.
  In transferring to the bulb, the water should be agitated 
SANITARY  EXAMINATIONS.
59
as little as possible in contact with the air, in order to
avoid the absorption of oxygen.  A siphon should be used
for this purpose, the lower end being allowed to reach to
the bottom of the bulb.
   Dupre has employed the determination of free oxygen
for the estimation of the proportion of oxygen-consuming
microbes.  The  principle  of  the  method is that water,
if kept in  a closed bottle, will  not lose  oxygen in any
length of time, unless organisms capable of causing absorp-
tion of oxygen are present.
   The experiment is  carried  out  by placing a sample of
the water in  a clean bottle, and  vigorously  shaking  it to
saturate with air.  A  clean 250 c.c. bottle  is completely
filled with the water, tightly stoppered, and  maintained at
a temperature of 200 C. for ten days; the free oxygen re-
maining is then determined.

                  POISONOUS METALS.
   Under this conventional  title  are included  barium,
chromium, zinc, arsenic,  copper, and lead; manganese, iron,
aluminum,  also, though not usually classed in this group,
are objectionable when present in notable amounts.
   Barium is rarely present, and only in water containing
no sulfates.   It can be detected  and estimated  by slightly
acidifying  the water with hydrochloric acid, filtering  if
necessary, and adding solution  of calcium  sulfate.   The
precipitated  barium  sulfate is collected and weighed in
the  usual way.
   Chromium is rarely present,  but may be looked for in
the waste waters of dye-works and similar  sources.   To
detect it, a considerable volume of the water is  evaporated 
6o
ANALYTIC  OPERATIONS.
to dryness with addition  of a small amount of potassium
chlorate and nitrate, transferred to a porcelain crucible and
brought to quiet fusion; any chromium present will be
found in the residue in the form of chromate.   The fused
mass, after cooling, is boiled with  a  little water, filtered,
the filtrate rendered slightly acid with hydrochloric acid,
and  a solution of hydrogen  dioxid added.   In  the pres-
ence of chromium a transient blue color will appear; by
adding a little ether and shaking  the mixture,  the color
will pass into the ether, and  on standing will form a blue
layer on the surface of the water.
   Zinc is best detected by the test described by Allen.
The water is rendered  slightly  alkaline by addition of
ammonium hydroxid,  heated to boiling, filtered, and the
clear liquid treated with a few drops of potassium ferro-
cyanid ; in the presence even of  the  merest trace of  zinc
a white precipitate will be produced.
   Arsenic is most readily detected by Reinsch's  test.
One liter of the water  is rendered slightly alkaline by  pure
sodium carbonate, and evaporated  nearly to dryness  in a
porcelain basin.  Two or three c.c. of water strongly acidu-
lated with hydrochloric acid are placed in a small test-tube,
about  ^ of a square  centimeter of bright copper foil is
added, and the liquid boiled gently for a  few moments.  If
the copper remains bright, showing that the reagents con-
tain no arsenic, the water-residue  is acidified with hydro-
chloric acid, added to the contents of the test-tube, and the
liquid again boiled for several minutes.  If arsenic be pres-
ent, a steel-gray stain will appear on  the copper.  The slip
is removed, washed with distilled water, thoroughly dried by
pressure between filter paper, inserted into  a narrow glass 
SANITARY  EXAMINATIONS.
6l
 tube closed at one end, which has been previously dried by
 heating nearly to redness.  The tube is gently heated at
 the point  at which the copper  rests ;  the deposit  will
 sublime and collect  on the  cooler portion of the tube, in
 crystals which the microscope shows to be octahedral.
   Since small  amounts  of arsenic  frequently  occur in
 reagents and in glass vessels, care must be taken to avoid
 such  sources of error.  Sodium carbonate  solution may
 contain arsenic dissolved from the glass  bottle in which
 it is kept.   It is best, therefore, to use the solid carbonate
 for rendering  the  water alkaline, and to  determine its
 purity before use.
   Iron is  detected by the addition of a drop of ammonium
 sulfid  to the water in a  tall, glass cylinder.   Ferrous  sul-
 fid is formed,  having a greenish-black color,  instantly
 discharged by acidifying the water with dilute hydrochloric
 acid.   A still better test is the production of a blood-red
 color, with potassium thiocyanate, due  to the formation
 of ferric thiocyanate.  The water should be  first boiled
 with  a few drops of nitric acid, to convert the iron to the
 ferric condition, cooled, and a drop or two of the solution
 of potassium thiocyanate added.   The  test is very deli-
 cate.   Either of the  above tests may be made quantitative
 by matching the color produced in ioo c.c. of the water
 with that obtained  from a known weight of iron.  The
method with potassium thiocyanate is preferable, as it is
 more  delicate and there are fewer interfering conditions.
The following is the method as elaborated by Thompson
and described in Sutton's " Volumetric Analysis "  :
 Solutions Required :
  Standatit Ferric Sulfate.—0.7 gram ferrous ammonium 
62
ANALYTIC  OPERATIONS.
 sulfate  are dissolved in water acidified with sulfuric acid,
 and potassium  permanganate solution added until the
 solution turns a very faint pink color.  The solution  is
 diluted to a liter.   One c.c. contains  o. i milligram  iron.
   Diluted Nitric Acid.—Thirty  c.c.  concentrated nitric
 acid diluted with water to about  ioo c.c.
   Potassium Thiocyanate.—Five grams of  the salt  dis-
 solved in about  ioo c.c. water.
 Analytic  Process :
   About ioo c.c. of the water are evaporated to small bulk,
 acidified with hydrochloric acid, and  just sufficient dilute
 potassium permanganate solution added to convert all the
 iron to the ferric condition.  The liquid is evaporated
 nearly to dryness to drive off excess of acid, then diluted
 to  its  original  volume,  ioo  c.c.    In two tall  glasses
 marked  at  ioo c.c,  5  c.c. of the  nitric  acid and  15
 c.c. of  the thiocyanate solution  are placed.   To  one of
 these a  measured volume of the treated water is added and
 both vessels filled up to the mark with distilled water.  If
 iron is present, a blood-red color will be produced.  Stand-
 ard iron solution  is added to the second  vessel until the color
 agrees.   The amount of water which is added  to  the first
 glass will depend upon  the quantity of iron it  contains  ;
 not more should be used than will require two or three c.c.
 of the standard  to  match it, otherwise the color will be
 too deep for  comparison.
   Manganese.—The  following method is described qy
 Wanklyn in his treatise on water analysis.   About one liter
of the water is evaporated to small bulk, nearly neutralized
by hydrochloric  acid  and  treated with a few  drops of a
solution of hydrogen  dioxid.   The formation of a brown 
SANITARY  EXAMINATIONS.              6t,
 precipitate indicates the presence of manganese.   The test
 is very delicate.   The  precipitate  may be collected  on
  filter, the filter ashed, and the residue fused with a mix-
 ture of sodium carbonate and potassium nitrate.  Green
 potassium manganate will be produced, which, when boiled
 with  water, will  give a  bright-red solution of potassium
 permanganate.  The quantitative determination is given
 elsewhere.
   Aluminum.—Traces of this element  are  to  be ex-
 pected in all waters, and it is not usual to test for it except
 in elaborate  analysis of  the  mineral ingredients, as de-
 scribed in  another section.   The use of aluminum sulfate
 as a coagulant in many rapid-filtration  methods  makes  it
 necessary to examine effluents for excess of precipitant, and
 this  may be  done  by  the following  method  devised  by
 Mrs.  Richards :
   To 25 c.c.  of the water to be tested (concentrated  from
 one  liter or  more, if necessary) is added  a few drops of
 freshly prepared logwood decoction ; any alkali is neutral-
 ized and the color  is brightened by the  addition of two
 or  three  drops  of acetic  acid.    By  comparison  with
 standard solutions, the amount of alum present may be
 determined.   One  part of alum in 1,000,000 of water can
 be detected with  certainty.   In cases of greater dilution,
 concentration  of  several liters may be necessary to obtain
 a decisive test.  The logwood chips yield the right color
 only after having  been treated with  boiling water  two ot
 three  times, rejecting the successive decoctions.   The first
portion gives  a yellow  color, the third or  fourth usually
a deep red.  The logwood chips must be fresh.
  Lead may  be readily detected by adding  to the water in 
64
ANALYTIC  OPERATIONS.
a tall glass cylinder a drop of ammonium sulfid ; brown-
ish-black lead sulfid is formed, which does not dissolve
either  by acidulating the water with dilute  hydrochloric
acid (distinction from  iron), nor by the addition of about
one  c.c. of a strong solution of potassium  cyanid (dis-
tinction  from copper).   S. Harvey gives the  following
method : 250 c.c.  are placed in a precipitating  jar, about
0.1 gram of  crystallized  potassium  dichromate is added
and dissolved by agitation.  The same volume of lead-free
water is treated in  the same manner, and the  two solutions
placed side by side.  Water containing 0.3 part per  mil-
lion  will show a turbidity in fifteen minutes which will be
rendered more distinct  by contrast with the clear water
alongside.  By allowing the jar to stand for about  twelve
hours undisturbed, the precipitate will settle and will be-
come still  more distinct.   No  other  metal likely to be
present in water will give a similar reaction.
  In  the absence  of copper the amount of lead present
may be determined as follows :  A solution is prepared con-
taining 1.6 grams of lead nitrate to the liter; one c.c.  of
this contains  one  milligram lead.   One  hundred  c.c.  of
the water to  be tested are placed in a  tall glass vessel,
made acid by the  addition of a few  drops of acetic acid,
and  five c.c  of hydrogen sulfid added.    In  a similar
vessel  100 c.c. of distilled water are placed, together with
the same  quantities of acetic acid and  hydrogen sulfid,
and sufficient of the standard  lead  solution  to  match the
tint in the first cylinder.  The amount  of lead in the water
under examination is thus known.
  Copper is detected in the  same manner as lead by
acidifying the water with acetic acid and adding hydrogen 
SANITARY  EXAMINATIONS.
65
sulfid.   The precipitate  is distinguished  from lead sulfid
by the fact  that  the color is discharged  on the addition
of about one c.c. of a strong solution of pure potassium
cyanid.  It may be further confirmed by the addition to
another portion  of the water of a solution of potassium
ferrocyanid.  In the presence of even a very small amount
of copper, a mahogany-red color is produced.
  In the absence of lead, copper is estimated in the same
way as that metal, using, however, a standard solution of
copper for  the  comparison liquid.  This  is made by dis-
solving 3.929 grams of crystallized copper  sulfate in one
liter of  water.   One  c.c. of  the solution contains one
milligram copper.
  If both lead  and copper are present, a large quantity of
the water  should be  evaporated  to small  bulk, and the
metals separated and estimated by any one of the ordinary
laboratory methods.

              BIOLOGIC  EXAMINATIONS.
  In a comprehensive  sense the living  organisms of water
include representatives of all  the  great groups of animals
and plants.  The  higher orders of organic forms are absent
from very foul  water.   From  an  analytic point of view,
observation is limited to  the determinations  of those forms
which are inappreciable  to the unassisted eye.   So far as
regards some of  the moderately complex  organisms, such
as the minute  crustaceans, algae, desmids,  and even the
amebae, it may  be said that while some general inferences
as to the character and  history of the water may be deduced
from an identification of the specific  forms, no definite
sanitary signification can be attached to them.  The ova
       E 
66
ANALYTIC OPERATIONS.
of the entozoa might in some cases be detected by careful
search, and would  indicate recent pollution of a highly
dangerous character.
  Cohn regards chlorophyl-producing plants (diatoms and
green algae), together with  the  infusoria that  feed  upon
them, and species of entomostraca (Daphnia and Cyclops),
when present in only  moderate  amounts, as  indicating
water not very rich  in dissolved organic matter.   Species
of  Cladothrix,   Crenothrix,  and  Beggiatoa,  which  are
among the larger bacteria and frequently appear as branch-
ing forms, indicate  suspended organic matter,  while dis-
solved organic matter in a state of active decomposition is
indicated  by the presence  of ordinary bacteria {Bacilli,
Spirilla),  etc.
   Cladothrix dichotoma withdraws iron from water, and
fixes it, causing obstructions in iron water-pipes.   Creno-
thrix Kiihniana Rabenhorst is seen in water containing
iron and sometimes causes a disagreeable odor.
  The number  of the higher forms present in any sample
will depend very much upon the point  at which it is col-
lected, they being more numerous  in the neighborhood of
large  plants  and at the bottom  and  sides of streams.
Under our present  knowledge, no pathogenic  power  can
be assigned to  the  higher forms  of organic life, except
entozoa, but  their bodies after death may indirectly con-
tribute to the rapid increase of the bacilli proper, by serving
as food.
  Several observers, notably Sedgwick and Rafter, have
paid considerable attention  to the recognition of the ani-
mal and vegetable forms in  surface waters.   Some of these
forms, while not apparently directly  disease-producing 
SANITARY  EXAMINATIONS.
67
cause disagreeable  odors and colors  in water;  in  the
warm season of the year, when these waters are stored in
reservoirs, considerable annoyance is felt by the users, and
the  engineer-in-charge  is subjected to much  criticism.
For some years the American  Water-works Association has
had a special committee engaged in collecting data bearing
upon this point, and devising methods for preventing  the
conditions.   No satisfactory explanation or remedy has yet
been offered by this committee,  but it has been found that
even crude  filtration methods, such  as  allowing the water
to pass through a dike of porous soil before storing it in a
reservoir, will diminish  the tendency to these conditions.
Cleansing a  reservoir, disinfecting  the inner surface, for in-
stance, by whitewashing, has also improved the condition.
   Extended observations,  especially   in  Massachusetts,
have shown  that  reservoirs  intended for even moderately
prolonged storage  of  water should  be  clean—that is, or-
ganic matter of any kind should  not be allowed to accu-
mulate on the bottom and sides.   Drown states that while
the water in  one basin became foul from  stagnation, in
another which  was carefully prepared  by the removal of
all soil and  vegetable matter,  and  is supplied by a brown,
swampy  water from a district almost  entirely free from
pollution, the water is good at a depth of forty feet.
   In Philadelphia,  where large storage  reservoirs are used
for water that is often very muddy, but little trouble from
the growth of microscopic organisms occurs.  These reser-
voirs are artificial basins.
   Sedgwick's method, with  some modifications  by Dr.
Williston, is as follows :
   In ordinary cases about 100 c.c. are employed.   Some- 
68
ANALYTIC  OPERATIONS.
 times it will be  advantageous to use double  this quantity,
 at other times much less.   In rare cases the examination
 can be made upon  unfiltered water.  Originally sand was
 employed  for a filter material,  but Williston finds  that
 precipitated silica, made by decomposing silicon fluorid
 with water, is more satisfactory.   This precipitated silica is
 a  commercial  article, and its  method of preparation is
 given in all the larger manuals of chemistry.
   A small glass funnel with  an  even-calibered stem is
 selected, and the lower  end of the stem  plugged with a
 little  absorbent cotton, upon which a layer three  or four
 mm. deep  of the filter-material  is  placed.   The requisite
 volume of  water is  then allowed to filter through.  The
 pledget of cotton  is removed, and the filter-material  is
 washed down with filtered  or distilled water  into a  cell
 intended for microscopic examination.  This cell is a glass
 plate accurately ruled, to which is attached a brass cell 50
 mm. long  by 10 mm. wide, of depth sufficient to  hold
 about two  c.c.  of water.   After the material has  been
 allowed to  distribute  itself and  settle  in  the cell,  it  is
 examined with a moderate power, and the different organ-
 isms in a varying number of the  squares counted.   Each
 organism may be counted  by itself, if occurring in large
 numbers, the average of a  few squares being sufficient for
 the purpose.  Organisms less numerously represented may
 be counted by averaging a larger number of squares.
  Filtering in this manner can not be relied upon in  all
cases.    Indeed, in  most cases  the unfiltered water also
should  be  examined.   Some of the minute unicellular
organisms pass readily through the small extent of sand or
precipitated silica, or even through  filter-paper. 
                SANITARY EXAMINATIONS.             69

   It is not unlikely that the high-speed centrifugal appara-
tus now  used in laboratories, associated with the employ-
ment of  some fine precipitant,  will aid  in these investiga-
tions.   (See page  142.)
   Owing to the great differences in the size of micro-
scopic organisms,  the  mere enumeration of  their  numbers
is not always an index of the amount of living matter in
suspension.   To obviate  this,  Mr. George C. Whipple,
biologist to the Boston Water Board, has suggested a stand-
ard  unit  of size,  estimating by  means  of it the  total
volume  of  the  organisms,  and not  their  number.   He
finds by  this method that the analytic and biologic results
correspond much more closely than when mere  numbers
are recorded.   The unit is an  area of 400 microns—that
is, a square  of  20 microns on  a  side.  The  results are
stated in number of standard units per cubic centimeter.
   Mr. Whipple  has investigated the conditions influencing
the growth  of the microscopic  organisms in water.   He
finds that diatoms  thrive best with  a supply of nitrates and
a  free circulation  of air; temperature alone has no very
direct effect.  Infusoria will be  found in  largest  numbers
when the water contains the greatest  amount of  finely
divided organic matter.   When the conditions bring about
a circulation of the water,  the organisms are not  only
brought constantly in contact with new food  materials, but
are enabled to reach the upper  layers of the water where
oxygen is abundant.
   The introduction of the ova of entozoa into  the human
system by means  of water is doubtless a very common
occurrence,  and cases have been  reported.  One of the
most striking of  these was the anemia occurring  among the 
70               ANALYTIC  OPERATIONS.

workmen  in  the  St.  Gothard tunnel, which was found  to
be due to the ingestion of  the ova of a parasitic animal,
Anchylostomum duodenale.
  Culture-media.—For   bacteriologic  examinations,
culture-media  prepared with  gelatin  or  agar are  gen-
erally used.  In special cases potatoes and blood-serum are
employed.   In  all  cases  solutions and vessels must  be
thoroughly sterilized.   This is most easily accomplished in
the Arnold steam sterilizer.  It consists of a copper boiler,
in the form of an inverted funnel, which communicates
with   the  sterilizing chamber.   A double  casing is  so
arranged  that  the condensed steam falls into the pan and
returns to the boiler.  This pan should be about half filled
with water before starting.   This apparatus is suitable not
only for all sterilizations, but also  for preparing solutions
and for hot filtrations.
   Meat-extract-peptone-gelatin :

      Water,...............iooo c.c.
      Commercial meat extract,   ......   5 grams.
      Gelatin,..............150   "
      Peptone,..............   10   "
      Glucose,.............   2   "

   Liebig's meat extract  is  most  generally recommended
 by bacteriologists, but this  title is used by several manu-
 facturers, and Armour's  extract will be found quite satis-
 factory.   A  "meat infusion"  is advantageously substi-
 tuted  for the extract.   This infusion is prepared by soeiking
 500  grams of finely-minced lean  meat  for  twenty-four
 hours in  one liter of water at a  temperature not over 70
 C, and  then removing the liquid by  straining  through 
SANITARY EXAMINATIONS.             71
a cloth.    To  this liquid the other ingredients  may be
added.
  Agar Mixture.—When cultures are to be conducted at
a temperature above 68° F., agar must be used  as gelatin-
izing ingredient.   The solution is prepared as given above,
except that longer time will be required for the  solution of
the  gelatinizing  material.   The operation can be  facili-
tated by  soaking the agar for twelve hours in a strong
solution  of common salt, or by the following  treatment,
which was first described by Mace :
   Twenty grams of agar, cut fine, are steeped for twenty-
four hours in 500 c.c. of water, containing six per  cent.
of hydrochloric acid, with occasional stirring.  It is then
well washed, and  placed for a similar period in the  same
amount of water, to which six per cent, of ammonium
hydroxid has been added.  It is again washed  thoroughly
and added to 1000 c.c.  of boiling water.   It dissolves at
once.   The  peptone, gelatin, and salt can then be added,
the  mixture  rendered feebly alkaline, and filtered in the
sterilizer.
   The following formula for nutrient agar has been  much
used in a private laboratory in Philadelphia:

      Agar,...............   12  grams.
      Liebig's meat extract,  ........    3    "
      YVitte's dry peptone..........   10    "
      Sodium chlorid,..........    5    "
      Distilled water,..........1000  c.c.

   Agar  Gelatin.—To secure  the advantages  of both agar
and gelatin, a solution may be made by dissolving 50 grams
of gelatin and 7.5 grams of agar in a liter of water, adding 
72
ANALYTIC OPERATIONS.
the peptone, etc., in the usual proportions, rendering alka-
line, filtering, and sterilizing.   The proportions of agar
and gelatin must be  adhered to closely or the gelatiniza-
tion may be lumpy and incomplete.
  Potato Culture. — Cultivation on potatoes has been much
used as  a method  of distinguishing  certain  microbes.
Large,  sound  potatoes  should be  selected,  thoroughly
washed, and cut into  disks about five centimeters in diam-
eter and one centimeter thick.   These are placed in glass
boxes (pomade boxes) which have lids with ground joint,
and  heated for about one-half  hour in  the sterilizer.
Another  method is to cut out cylinders with the aid of an
apple-corer, or largest size cork-borer, slice these obliquely,
and place  them in test-tubes, which are then closed with
cotton  plugs and sterilized.  The latter method  does not
give a  large surface,  but the  growth  of any inoculation
may be easily  watched.
  The  important question of the reaction of culture-media
has often been disregarded.    Mr. George W. Fuller has
given much attention to this subject, and  has found that,
strictly speaking, regular culture-media as used are neither
absolutely neutral, acid, nor alkaline, but the reaction de-
pends  upon the indicator used.   Many  are alkaline to
litmus  and acid to  phenolphthale'in ; the cause of this is
twofold—the presence of acid phosphates and of proteids ;
the latter  are  amphoteric, but  the acid reaction  predomi-
nates.   Phenolphthale'in  is  the best  and most  delicate
agent for determining reaction in culture-media.   Under
ordinary circumstances the phosphate present is Na2HPO .
To all  other indicators except turmeric and phenolphtha-
le'in this salt is alkaline; to the latter it  is neutral.   Ex- 
SANITARY  EXAMINATIONS.
73
periments  have shown that this  phosphate  exerts little
influence upon bacterial development;  in  fact, it is  less
active  than sodium chlorid.   Hence,  with litmus  as an
indicator,  this compound  reacts alkaline and prevents a
proper addition of  alkali, and as the proportions of  phos-
phates will vary in different  lots of culture-media,  the
degree of  reaction can  not be accurately  controlled  by
means of litmus.
   Mr. Fuller  recommends "neutrality to  phenolphtha-
le'in " as a "datum point" for reaction.  The expression
of the reaction in parts or in percentage is inaccurate  and
awkward.  It  is  suggested that reaction be expressed in
terms of normal  solution necessary to render one liter of
the medium  neutral to phenolphthale'in.  As, ordinarily,
the media are acid, it is convenient to call the acid num-
ber plus, the alkaline number, minus.
   The procedure advised is to get all  ingredients in solu-
tion, mix well, place 5 c.c. in a 15 cm. porcelain dish,  add
45 c.c of distilled  water, boil three minutes, titrate with n
alkali, using  phenolphthale'in  as  an  indicator,  calculate
and add the  amount of normal alkali  necessary to  make
the main bulk of the solution neutral, heat for a short
time, mix  well,  filter,  and titrate again.    Hydrochloric
acid is now added in such  amount that 15 c.c. of normal
alkali are  necessary  to  make  one  liter of the  medium
neutral to phenolphthale'in.  This is for special work.   In
general work,, using  1  c.c. of the water sample to  5  c.c.
of culture-medium, the acidity is increased one-fifth to
offset the dilution.
  The following  table, condensed from Mr.  Fuller's com-
munication, shows very clearly  how reaction  influences the 
74
ANALYTIC OPERATIONS.
number of points of microbic life developed  in  any given
sample :
C.c. of Normal So-       Points of Microbic Life in One c.c.
 lution Required___________________a------------------N
imac Kivet Water.	Filtered Water.
IOO	4
7,800	84
15,000	184
6,900	80
5,800	66
3,200	48
200	ij
 to   Neutralize
 One Liter of the  Lawrence Sewage.
 Culture-medium.             *
       40            168,000
       25           1,720,000
       20           2,688,000
        5           2,625,000
        o           2,234,000
     —10           2,230,000
     — 25           1,520,000
  — indicates alkalinity to phenolphthalei'n.

  Many special forms of culture-media are employed  for
bacteriologic investigations which do not come within  the
line of water analysis, and need not be described.  One
form is much employed in the search for the specific germ
of typhoid fever,  namely,  Wurtz's litmus-lactose solution.
This may be with either  agar or gelatin, in conjunction
with meat extract.   The nutrient medium must be  made
so as to possess such  a degree  of alkalinity that 10 c.c.
will neutralize  1 c.c. of  —sulfuric acid.   Lactose is added
                        20
in the proportion of two or three  grams  to 100 c.c. of
medium and the  mixture  sterilized,  after which sufficient
sterilized litmus tincture is added to give the fluid a dis-
tinct but not deep-blue color.
  Cultivation in gelatin at ordinary temperatures usually
yields a larger  number of  points of  microbic life than in
agar at blood-heat.   This  is  due to the fact that  many
common water bacteria do not  grow well at the  higher
temperatures. 
SANITARY  EXAMINATIONS.
75
  Culture Methods.—For water examinations it is now
customary to use the Petri  dish.   This is a shallow glass
dish with upright rim and a cover of similar  shape fitting
loosely.  For making cultures, portions of  the nutrient
material  are placed in  test-tubes, which are  then closed
with plugs of cotton and sterilized in the steam sterilizer.
The tubes are removed, allowed  to cool to about blood-
heat, measured volumes of the water added,  the  mixture
shaken and poured into the Petri dish, a separate dish
being used for the contents of each tube.  Of course, the
dishes  and  covers must have been thoroughly sterilized
just  previous  to  using them.  The dishes are promptly
covered  and cooled, being leveled so  that  the contents
solidify  in a  flat layer of even  depth.   They are  then
kept at  the  proper temperature.   As  a  rule, points of
microbic life  begin to be visible  very soon.  When the
number  is  small,  the  count may be made  directly,  but
when many points are developed, it is necessary to count
some area of known proportions and the total number ap-
proximated by calculation.  To  aid in this work various
" counting plates " have been devised.   For use with Petri
dishes, Abbott recommends Pakes' modification of Lafar's
apparatus.   This is a circular paper disk, ruled with  radii
and concentric circles.   It can be obtained  from  dealers
in bacteriologic apparatus.
  Some operators maintain the original water  samples, as
collected in sterilized vessels, at blood-heat for from thirty-
six  to  forty-eight  hours, and  then prepare  the cultures.
The principle  involved  is  the same  as that applied in
Vaughan's methods, on page 79. 
76
ANALYTIC  OPERATIONS.
  General Character of  the  Microbes  in Natural
Waters.—The microorganisms of natural waters are prin-
cipally  included in the genera  Bacillus and Spirillum,
especially the former.   Micrococci  and molds are rare,
and are generally due to contamination by dust.
  Microbes are  distinguished according to the conditions
favorable to their growth, as follows :
  Saprophytic.  Growing on dead matter.
  Parasitic.  Growing only on living matter.
  Aerobic.   Requiring free oxygen.
  Anaerobic.   Not requiring free oxygen.
  When the organism possesses the  power of adapting it-
self to different conditions, the term facultative is applied ;
when it can grow only under special  conditions, the term
obligatory is applied.
  Microbes are also differentiated by the effect which they
produce upon the culture-medium.  Some species  rapidly
or slowly liquefy the jelly with evolution of  foul-smelling
gases ; others—chromogenic microbes—produce character-
istic colors.   Many do not produce any positive modifica-
tion, and  for purposes of distinction it is usual to transfer
portions of the colonies  to other  culture-media.   Such
special cultures  are  obtained by taking up  a portion of
the  colony on the end of a wire which has been just ster-
ilized by heating to redness  and inoculating the prepared
medium.
  Cultivation in Absence of Oxygen.—Several of the most
frequently  occurring microbes are obligatory  anaerobes,
and will grow, therefore, only in  an  atmosphere deprived
of free  oxygen.  Carbon dioxid has  been  found to act
unfavorably upon their development.   The  most suitable 
SANITARY EXAMINATIONS.
77
atmosphere is one of pure hydrogen.  Cultivation in such
an atmosphere may be secured by constructing the moist
chamber so as to permit its being filled with hydrogen and
sealed, or by the use of Liborius' tube, figure 9.
  The tube  is charged with  nutrient jelly, plugged with
cotton, sterilized, inoculated with the material to be tested,
the jelly maintained in a liquid condition by a very gentle
heat and a current of pure hydrogen  passed  through the
side tube until all air is expelled.   The test-tube and side-
tube are then sealed quickly at the narrow portions, in the
blow-pipe  flame,  and the jelly allowed  to '
solidify.                                    1  -1
  Staining.—The  differentiation  of the   \ /
various  species  of microbes  may  also  be   J \
accomplished  by  staining   with  various_______
anilin colors.   These  methods are,  how-     f~
ever, more  generally applicable  to patho-
logic work—that is, to the staining of mi-
crobes in tissues.                            ^-~
  Indol Reaction.—Indol,  CMH7N,  more      fig. 9.
properly indin,  is a  weak base, which is  a
product of the growth of many species of microbes, and
the detection of  it may, therefore, be  utilized as a differ-
entiation test.   Kitasato  gives the following method for
performing the test:
  Ten c.c. of an  alkaline-peptone-meat infusion (without
gelatin), which  has been previously inoculated with the
microbes to  be  tested, and kept  for twenty-four hours at
blood-heat,  are  treated  with  1 c.c.  of solution of pure
potassium nitrite (0.02 gram  in 100  c.c.) and then with
a few drops of concentrated  sulfuric  acid.   In  the  pres- 
78
ANALYTIC  OPERATIONS.
ence of indol a rose or deep-red color is developed.   Spi-
rillum cholera and Bacillus coli communis give the reaction
strongly ; S. Finkleri feebly ;  the so-called B. typhosus
ordinarily does  not  give it.
  An effort has been made to distinguish  dangerous mi-
crobes by employing  crucial  conditions  of  cultivation
which are believed  to eliminate the harmless forms.   One
of the most complete methods  is  that used in the  Hygi-
enic Laboratory of  the University of Michigan, under the
supervision of Dr. Vaughan :
  The water'is  collected in sterilized bottles, and beef-tea
tubes are inoculated with  it,  from one  drop to  one cubic
centimeter being added  to  each  tube.  The inoculated
tubes are kept at 380  C.  for twenty-four hours.
  Many germs found  in  drinking-water will not grow at
so high a temperature.  It is assumed that a germ which
will not grow at the temperature of the human  body can
not possibly induce  disease.   Of the germs which do grow
at 380 or higher, some are toxicogenic to  animals, while
others  are not.   Whether the  germs in a given sample
are  toxicogenic  or not, is determined by injecting the pre-
pared cultures subcutaneously or intra-abdominally in rats,
guinea-pigs, rabbits, or mice.
  Waters  not  containing toxicogenic  germs growing at
38 ° or higher are reported as safe.
  Waters  containing toxicogenic germs growing at 380 C.
are  condemned.   In testing virulence,  a germ  is not
pronounced  toxicogenic  unless it  be found growing and
multiplying in the animal inoculated with it.
  The Franklands,  after reviewing at length  the various
methods that have  been suggested for differentiating the 
SANITARY  EXAMINATIONS.             79
typhoid bacillus, show that most of them are quite insuffi-
cient.   A routine treatment is,  however, suggested as fol-
lows :
  The water  is  freed  from the  ordinary water-bacteria
by preliminary culture  in  Parietti's  solution.   This  is a
phenol-broth  prepared  by  mixing  10  c.c.  of  neutral
bouillon with 0.25 c.c. of the following solution :

      Phenol, ......
      Hydrochloric acid,
      Water,.....

  This solution is sterilized by  heating it for  twenty-four
hours at 370 C.   The tubes are then inoculated with from
one to ten drops of  the water sample,  which  must be
thoroughly mixed with the broth, and  again  kept in  the
sterilizer  for. not less than  forty-eight hours.   If any of
the tubes appear turbid after the treatment, they should be
submitted to plate cultivation, and  any colonies which
resemble those produced by the typhoid bacillus should be
further studied by inoculation into gelatin tubes to observe
the  gas-producing test, into milk to  note if coagulation
occurs, and by cultivation in broth to  determine if indol-
reaction will be obtained.
   Vaughan investigated the application of various methods
for the isolation of a specific bacillus,  but did  not obtain
satisfactory results.
   Klein has pointed out that in most of the methods for
isolating pathogenic microbes, the volume of water used is
too small.  He  suggests the employment of at least 1000
c.c   Obviously, this volume will give a better sampling
than the few drops or 1 c.c. generally  used.
  5 grams.
  4   "
100   " 
8o
ANALYTIC  OPERATIONS.
   Bacteriologic examinations of water are usually limited
to  microbe-counting,  determination  of  the number  of
colonies  developed  on  the  culture-plate, and  isolation
of  B.  coli communis  or closely  analogous  form.   Few,
if any, careful  and  experienced bacteriologists now claim
to  be able  to  detect  with  certainty  the B.  typhosus  in
ordinary  cases.   The resemblance between the two forms
is so great, and  the  variability of both  forms so marked,
that  some   observers have  suggested  that they are  but
varieties  of the  same  specific  bacillus.   Much  attention
has been  paid to the distinctions.   The following synopsis
has been  given  by A. C.  Abbott:
   Characteristics.
Motility,  ....
Growth in gelatin, .
  "    " potato,

       " milk,
      B. Typhosus.
. Conspicuous.
. Slow.
. Usually inconspicuous.

.No coagulation;  no
   acidity.
Growth in media con-
  taining glucose, lac-
  tose, or sucrose, .  . No evolution of gas.

Growth in media con-
  taining lactose  and
  litmus,......Colonits pale blue ;  no
                      reddening  of  sur-
                      rounding medium.
Indol reaction  in pep-
  tone solution (forty-
  eight hours at 38°C.) Rarely present.
 B. Coli Communis.
Not marked.
Not very slow.
Always rapid and visi-
  ble.
Acidity and  coagula-
  tions in forty-eight
  hours in incubator at
  38° C
Marked  evolution  oi
  gas.
Colonies  pink ;   sur-
  rounding   medium
  red.
Always present. 
                 TECHNIC EXAMINATIONS.              81

   It will be seen that the characteristics of B. typhosus are
rather negative than positive.   The data are derived  from
cultures  obtained from intestinal discharges or viscera of
patients affected with typical typhoid fever.


             TECHNIC  EXAMINATIONS.
         GENERAL QUANTITATIVE ANALYSIS.
   Silica,  Iron,  Aluminum, Manganese, Calcium,
and Magnesium.—One liter of the water acidified with
hydrochloric acid is evaporated to complete dryness, best
in a platinum dish, the residue  treated with hydrochloric
acid and water, and the separated silica filtered,  washed,
dried, ignited in a platinum crucible,  and weighed.
   To  the filtrate, previously boiled with a few drops of
strong nitric acid, slight excess  of ammonium hydroxid is
added, the liquid boiled several  minutes,  the precipitate
collected, washed thoroughly with  boiling water, dried,
ignited,  and  weighed.   It consists of Fe2Os and A1203.
It also contains all the phosphates and some manganese if
much is present in the water.  In such cases the precipitate
before drying  is  redissolved  in  hydrochloric  acid and
neutralized with a dilute solution of ammonium carbonate
until the water becomes almost turbid.   It  is then boiled,
and  the  precipitate, now free from manganese,  washed,
dried, ignited, and weighed.  The iron may be determined
by dissolving the  precipitate in strong hydrochloric acid
and employing the colorimetric method described  on page
61.
  If no manganese or only  traces are present, the filtrate
       F 
82
ANALYTIC  OPERATIONS.
from the iron  is mixed with sufficient ammonium chlorid
to prevent the precipitation  of the magnesium, ammonium
hydroxid, and then ammonium oxalate added in quantity
sufficient to precipitate the calcium and to convert all the
magnesium into oxalate, and thus  hold it in solution. The
precipitate contains all the calcium and some of the magne-
sium.  If the magnesium is present only in relatively small
quantity, the amount carried down may be disregarded ;
otherwise a second precipitation should be made as follows :
The solution is allowed to  stand  until the precipitate has
subsided ; this will require  some hours.   The supernatant
liquid is poured off through a filter,  the precipitate washed
by decantation, then dissolved  in  hydrochloric acid, water
added,  then ammonium  hydroxid and a small quantity
of ammonium oxalate.   After the calcium oxalate has
thoroughly subsided it is filtered off, washed, and dried.  If
quite small in amount, it is placed with the filter in a weighed
platinum crucible, ignited  over  the Bunsen burner for a
short time, and then  over  the blast lamp  for from five  to
fifteen minutes.  The calcium  is thus obtained in the form
of oxid, which is allowed  to  cool  in the desiccator  and
weighed.  The weight thus obtained multiplied by 0.714
gives the weight of calcium.  When the amount of precipi-
tate is large, it is better  to remove  it from  the filter,  and
heat it just short of redness until it assumes a grayish tint.
It then  consists of  calcium carbonate.   To this is  added
the ash of the filter.  The weight of the calcium carbonate
multiplied by 0.4 gives the weight of calcium.
  The  filtrates are mixed, slightly  acidified with  hydro-
chloric acid, concentrated and cooled, ammonium hydroxid
and  sodium  phosphate  added  in excess,  stirred briskly 
TECHNIC EXAMINATIONS.
83
and allowed to stand in the cold for about twelve hours.
The  precipitated  ammonium magnesium  phosphate  is
brought upon a filter, that adhering to the sides of the ves-
sel being dislodged by rubbing with a glass rod  tipped with
a piece of clean rubber tubing.   It is washed with a solu-
tion made by mixing one part of the ammonium hydroxid
of 0.96 sp. gr. with  three parts of water.   The precipitate
is dried,  transferred  to a platinum crucible, the filter ashed
separately and added  to it, and  the  whole heated at first
gently and  then to intense redness  for  several  minutes.
After cooling, it is  weighed.  It consists of  magnesium
pyrophosphate; the weight multiplied by 0.218 gives the
weight of magnesium.
   Manganese, if present in  appreciable quantity, is sepa-
rated before  the precipitation of the calcium,  as follows :
The filtrate from the iron precipitate is slightly acidulated
with hydrochloric acid, concentrated, and the  manganese
precipitated  as sulfid by colorless or slightly yellow solu-
tion of ammonium  sulfid.   The flask, which  should  be
nearly full,  is stoppered, allowed to rest in a  moderately
warm place  until the  precipitate has thoroughly settled,
filtered, washed with dilute  ammonium sulfid  water, and
purified by dissolving in a small  quantity of hydrochloric
acid  and reprecipitating with  ammonium  sulfid.   It is
filtered off, washed  as before, dried, placed in a weighed
porcelain crucible, covered with a little sulfur, and ignited
in a current of hydrogen introduced into  the crucible by a
tube passing  through a hole in the cover.   The pure man-
ganese sulfid  thus obtained is allowed  to cool and weighed.
The weight multiplied  by 0.632 gives manganese.
  Sulfates.—Five  hundred c.c. of the  clear water are 
84              ANALYTIC OPERATIONS.

slightly acidula'ted with hydrochloric acid, heated to boil-
ing, and  barium chlorid solution added  in  moderate ex-
cess.   The precipitated barium sulfate is allowed to sub-
side completely, collected upon a filter, washed thoroughly,
dried,  and incinerated.   The weight multiplied by 0.411
gives SOr   If  the proportion is very low,  it will be ad-
visable to concentrate  the water to  one-fifth or  one-tenth
its bulk before precipitating.
   Control.   Potassium, Sodium, and Lithium.—
From  250 to 1000  c.c. of the water, according  to the
amount of solid matters present, are evaporated  to dryness
in a platinum dish, and the residue treated with a small
amount  of  water and sufficient  dilute  sulfuric acid  to
decompose  the salts present.  The dish should then be
covered  and placed upon the water-bath for five  or ten
minutes, after  which any liquid spurted on the cover is
washed  into the  dish, the whole  evaporated  to dryness
and heated  to redness.   A  few  drops  of   ammonium
carbonate solution should then be mixed with the residue,
and the  ignition repeated to insure the removal of the last
portions of free acid.   In the majority of cases the only
basic elements present in considerable quantity are calcium,
magnesium, and sodium.   The sodium may be  determined
indirectly, therefore, by calculating from the  amount of
calcium  and magnesium  found, the calcium and  magne-
sium sulfate in the  residue,  and  subtracting  this  sum,
together with the silica,  from the total residue.
   For the determination of potassium  and sodium in ordi-
 nary well and river waters, not less than two  liters should
 be employed.   When lithium is to be determined, it is
 generally necessary to use much more.   In  any  case, as 
TECHNIC EXAMINATIONS.
85
the alkalies are to be weighed as chlorids, it is advisable,
if  notable amounts of sulfates are present, to precipitate
them by addition of barium chlorid.
   The  water  is  evaporated  to about  200 c.c,  a slight
excess of calcium hydroxid added to the hot liquid,—gen-
erally three c.c. of thin milk of lime will be sufficient,—and
the heat continued for several minutes.   It is then washed
into a 250 c.c. flask, disregarding the insoluble portion ad-
hering to  the dish, which, however, should be thoroughly
washed, and the washings added to the flask.   After cool-
ing, the flask is filled up to the mark  with distilled water,
thoroughly  mixed, the precipitate allowed to settle, and
the liquid filtered through  a dry filter.   Two  hundred
c.c of the filtrate are measured into another 250 c.c. flask,
ammonium carbonate and ammonium oxalate added, filled
with water up  to the  mark,  mixed, allowed to settle,  fil-
tered through a dry filter, 200 c.c. of the filtrate measured
off, and evaporated to thorough dryness in a platinum cruci-
ble, heating very cautiously at the last stages, to avoid loss
by spurting.   The  low-temperature  burner is suited  for
this purpose.   The crucible is now covered and cautiously
heated  to dull redness, cooled, and weighed.   The residue
contains the potassium, lithium, and sodium as chlorids.
It contains, sometimes, also,  traces of magnesium, which
may be removed  by treating  again with lime and ammo-
nium carbonate  and oxalate.   It  is  frequently of advan-
tage, in evaporating  these saline solutions, to  add, when
the solution becomes concentrated,  several cubic centi-
meters  of strong  hydrochloric acid.  This precipitates  the
greater portion of the salts in a finely granular condition,
and renders loss by spurting less liable to occur. 
86
ANALYTIC OPERATIONS.
   If potassium and  sodium chlorids only are present, the
residue is dissolved in a small quantity of water, an excess
of a  concentrated neutral  solution of  platinum  chlorid
added, evaporated to small bulk at a low heat on the water-
bath, some eighty per cent,  alcohol  added,  allowed  to
stand, the clear  liquid decanted  off on a small filter, and
the residue washed in this way several times by fresh, small
portions  of eighty per cent, alcohol.  The precipitate is
then washed  on to the filter with alcohol, washed  again
with eighty per cent, alcohol, thoroughly dried and trans-
ferred as far as possible to a watch-glass.   The small por-
tion on the filter is dissolved off and the solution placed in
a weighed platinum dish and evaporated to dryness.   The
main  portion  on the watch-glass  is then added, and  the
whole dried to a constant weight at about 2600 F., cooled,
and weighed.  The  weight  thus  found multiplied by 0.3
gives  the weight  of potassium chlorid.  This subtracted
from the combined weight of the  chlorids gives the weight
of sodium chlorid.
   Lithium, if present, is best separated before the treatment
with platinum chlorid.  The following method,  devised
by Gooch, gives good results :  To the concentrated solu-
tion of the weighed  chlorids, amyl alcohol is  added and
heat applied, gently  at first, to avoid  bumping, until  the
water disappears from the solution and the  point of ebulli-
tion becomes constant at a temperature which is  approxi-
mately that at which the alcohol boils  (2700 F.),  the
potassium  and sodium chlorids   are deposited,  and  the
lithium  chlorid  is dehydrated and taken  into solution.
The liquid is then  cooled, and  a drop or two of strong
hydrochloric acid added  to reconvert traces of  lithium 
TECHNIC EXAMINATIONS.
87
hydroxid in the deposit and the boiling continued until the
alcohol is again free from water.   If the amount of lithium
chlorid be small,  it will be found in the  solution and  the
potassium chlorid and sodium  chlorid in the residue, ex-
cepting traces which  can be allowed for.  If the  lithium
chlorid exceed ten or twenty milligrams,  the liquid may be
decanted, the residue washed with amyl alcohol, dissolved
in a few drops of water, and treated as before.  For wash-
ing, amyl alcohol, previously dehydrated by boiling,  is to
be used and the filtrates are to be measured apart from the
washings.   In filtering, the Gooch filter with asbestos felt
may be used with advantage, applying gentle pressure by
the aid of the filter-pump.   The crucible and residue are
ready for weighing after gentle  heating over the low-tem-
perature burner.   The weight of the insoluble chlorids is
to be corrected by adding 0.00041 for every 10 c.c. of amyl
alcohol in the filtrate, exclusive of the  washings, if  only'
sodium chlorid be present; 0.00051 for every 10 c.c if
only potassium chlorid, and 0.00092 in the presence of
both these chlorids.
   The filtrate and washings are evaporated to dryness in a
platinum  crucible  heated  with sulfuric acid,  the excess
driven off, and the residue ignited to fusion, cooled, and
weighed.   From the weight is  to  be subtracted, for  each
 10 c.c. of filtrate, 0.0005, 0.00059, or 0-00109, according
as only  sodium  chlorid, potassium chlorid,  or both  were
present in the original mixture.
   Hydrogen Sulfid.—The following method is taken
from Sutton's "Volumetric Analysis" :
 Reagents Required:
   Centinormal lodin.—Dry,  commercial iodin  is  inti- 
88
ANALYTIC  OPERATIONS.
mately mixed with one-fourth its weight of pure potassium
iodid and gently heated  between  two clock-glasses by
resting the lower on a hot plate.  The iodin sublimes in a
perfectly pure condition.  It is allowed to  cool under the
desiccator, 1.265 grams weighed  out, together with  1.8
grams of pure potassium iodid, dissolved in about 50 c.c.
of water, and the solution made up exactly to a liter.  The
liquid must not be heated, and care  should be taken that
no iodin vapor is lost.   One c.c.  is equivalent to 0.00017
H2S.   The solution is best prepared  in stoppered bottles,
which should be completely filled  and kept  in  the  dark.
It will  not even then keep very long, and should be stand-
ardized by  titration  with  a  weighed amount  of pure
sodium thiosulfate,  which  should be  powdered  previous
to weighing, and pressed between  filter-paper to absorb
any moisture.   Fifty c.c. of the iodin solution,  when of
full strength, will require 0.124 gram of sodium  thiosul-
fate.
  Starch Indicator.—See page 53.
Analytic Process:
  Ten  c.c, or any other necessary volume  of the  iodin
solution, is  measured into a 500 c.c. flask, and the water
to be examined  added  until the  color disappears.  Five
c.c. of starch liquor are  then added, and the iodin solution
run in  until  the blue copper appears ;  the flask is then filled
to the mark  with distilled water.  The respective volumes
of iodin and  starch  solution, together  with  the  added
water,  deducted  from the 500 c.c, will show the volume
of water actually titrated by iodin.   A correction should
be made as follows for the excess of iodin required to pro-
duce the blue color:  Five c.c. starch solution are  made 
TECHNIC  EXAMINATIONS.
89
up with distilled water to 500 c.c, iodin run in until the
color matches that in the test, and the volume of iodin
solution so used subtracted from the figure obtained in the
first titration.
  Hardness.   COs in Normal Carbonates.—Waters
containing considerable quantities of calcium and  magne-
sium  are said to be hard.   Since the  solution of calcium
and magnesium  carbonate  in water depends partly  upon
the presence of carbon dioxid, boiling  precipitates the
greater portion of the carbonates, the result  being to di-
minish the hardness—/. e., to soften  the  water.   Magne-
sium  and  calcium  sulfates and chlorids are not precipi-
tated in this way.   Hardness,  therefore, is  divided into
two classes, temporary and permanent,  the former being
that which may be  removed  by boiling.   The determina-
tion may be made either by titration or by soap solution.
  Titration Method.—This method is due to Hehner.
Reagents Required:
  Standard Sodium Carbonate.—1.06 grams of recently
ignited pure sodium carbonate are dissolved in  water and
the  solution diluted  to 1000  c.c.   One c.c = 0.00106
gram Na2C03, equivalent to 0.001 gram CaC03.
  Standard Sulfuric  Acid.—One  c.c.  of pure concen-
trated sulfuric acid is added to about 1000 c.c. of water.
Fifty c.c. of the standard  sodium carbonate are placed in a
porcelain dish, heated to boiling, a few drops of a solution
of phenacetolin or lakmoid  added, and the sulfuric acid
cautiously  run in from a buret until the proper change  of
color  occurs.   From  the figure thus  obtained,  the extent
to which the acid should be  diluted in  order  to  make 1
c.c  of the sodium carbonate equivalent to 1  c.c of the 
9o
ANALYTIC  OPERATIONS.
acid may be calculated.  The proper amount  of  water is
then added, and the solution  verified by again titrating.
Analytic Process:
   Te?nporary Hardness.—One hundred  c.c.  to  250 c.c.
of the water tinted with  the  indicator are heated to boil-
ing, and  the sulfuric acid  cautiously run  in  until  the
color-change occurs.   Each cubic centimeter required will
represent one part of calcium  carbonate or its equivalent
per 100,000 parts of the water.
   Permanent Hardness.—To  100  c.c.  of the  water is
added an amount of the  sodium carbonate solution more
than sufficient to decompose  the calcium and magnesium
sulfates, chlorids, and  nitrates present;  usually a bulk equal
to the water taken will  be  more than  sufficient.    The
mixture is  evaporated to dryness  in a nickel or  platinum
dish, and the residue extracted with distilled water.   The
solution is filtered through a very small filter, and the filtrate
and washings titrated  hot with sulfuric acid  as above ; or
25 c.c. of distilled water  may be poured on  the residue,
and the solution obtained filtered through  a dry filter, the
filtrate  measured and titrated.  The  difference between
the number of cubic centimeters of sodium carbonate used
and the acid required for the residue will give the perma-
nent hardness.
   If the water  contains sodium or potassium carbonate,
there will be  no permanent  hardness, and there will  be
more acid required for the filtrate than  the equivalent of
the  sodium  carbonate added.   From  this  excess  the
quantity of  sodium carbonate  in the water may  be deter-
mined.
   Since any alkali carbonate in the water  would be erro- 
TECHNIC EXAMINATIONS.
91
neously calculated  as  temporary hardness  by the  direct
titration, the equivalent, in terms of calcium carbonate, of
the alkali carbonate present should be deducted  from the
figure given  by the titration in order to get the  true tem-
porary hardness.
   The total  C03 in normal  carbonates  is  given  by the
direct  titration of  the water with  dilute  sulfuric acid.
One c.c. of the acid is equivalent to  0.0006 gram of C03.
   Soap Method.—Many chemists estimate hardness by
the use of soap solution.   The following is a description
of this  method,  as carried out  in the  laboratory of the
Massachusetts State Board of  Health :
Reagents Required:
   Standard  Calcium Chlorid Solution.—0.2 gram  of  Ice-
land spar is dissolved in dilute hydrochloric acid in a  por-
celain dish, the solution evaporated to dryness, redissolved
and reevaporated,  until a perfectly neutral salt remains.
This is dissolved in water and made up to one liter.   One
c.c. contains calcium  equivalent to 0.0002 gram calcium
carbonate.
   Soap Solution.—0.50 gram  of best quality, dry, white,
Castile soap is  cut into thin shavings, dissolved  in a mix-
ture of 250 c.c. of  96  per cent, alcohol and 250 c.c. of
distilled  water, and allowed to stand overnight  to settle;
50 c.c. of the  clear liquid  are then  made up to one liter,
enough alcohol being used to keep all of the soap in solu-
tion.    Fifty  c.c   of  the  standard  solution of calcium
chlorid,  which, according  to  the  table,  should take ex-
actly T4.25  c.c. of standard  soap,  are  used to  test the
strength.  The soap solution thus prepared does not change
perceptibly if air has no access  to it, and, if used with a 
92
ANALYTIC  OPERATIONS.
siphon buret  attached to the  bottle, will keep for five or
six weeks or longer.  It contains 5.2 grams of Castile soap
to the liter.
  For  the standardization of the  soap, and  for the deter-
mination of  the hardness  of any water, 50 c.c. of the
sample  or  of the  standard calcium  chlorid solution are
placed in a flask or bottle of 200 c.c.  capacity, and of a
convenient shape, and  the soap  solution added, yo-or y\
of a c.c. at a time, shaking well after each addition, until
a lather  is  obtained which is permanent for five minutes
and covers the entire surface of the liquid with the bottle
placed on its side.
  The soap  solution  must be added  in small  quantities,
especially in  the  presence  of  magnesium compounds.   If
much carbonic acid be liberated, it is well to remove it by
suction.  The table (see  next page) does not apply to hard-
ness above 12.5.  The  water tested requires more than
10 c.c. of  the standard soap solution, a smaller portion  of
25 c.c,  10 c.c, or even 2  c.c, as the case may require,
is measured out and made  up to a volume of 50 c.c. with
recently  distilled water.   This will keep the results  com-
parable with  each  other, although the  dilution  introduces
some error into the calculation.
  If the hardness of a water is given as  9.0, it  means that
in 100,000 pounds of water there is  of calcium and mag-
nesium salts  a quantity which gives the  same hardness  to
water which  would be given  by nine  pounds  of calcium
carbonate.  In order to soften this water for  manufacturing
purposes, about nine pounds of soda ash will be required,
and for laundry  purposes about ninety  pounds of soap.
  The following table gives the hardness corresponding to 
TECHNIC  EXAMINATIONS.
93
the number of cubic centimeters of soap solution used in
the analyses:
C.C OF		C.c. of	1	C.c. of	
Soap	Hardness.	Soap	Hardness. 1	Soap	Hardness.
Solution.		Solution.		Solution.	
0.7	0.0	3-7	4-1	6.7	8.4
0.8	O.I	3-8	4.2	6.8	8-5
0.9	0.3	3-9	4.4	6.9	8.7
1.0	0.4	4.0	4-5	7.0	8.8
1.1	0.6	4.1	4-7	7-i	9.0
1.2	0.7	4.2	4.8	7.2	9i
i-3	0.9	4-3	5°	7-3	9.2
1.4	1.1	4-4	5-i	7-4	9-4
i-5	1.2	4-5	5-2	7-5	9-5
1.6	1.4	4.6	5-4	7.6	9-7
i-7	i-5	4-7	5-5	7-7	9.8
1.8	1.6	4.8	5-7	7.8	10.0
1.9	1.8	4-9	5-8	7-9	10.1
2.0	1.9	5-o	6.0	8.0	10.3
2.1	2.0	5-i	6.1	8.1	10.4
2.2	2.2	5-2	6.2	8.2	10.6
2-3	2-3	5-3	6.4	8-3	10.7
2-4	2.4	5-4	6-5	8.4	10.9
2-5	2.6	5-5	6.7	8-5	11.0
2.6	2.7	5-6	6.8	8.6	11.2
2.7	2.8	5-7	7.0	8.7	"•3
2.8	2.9	5-8	7-i	8.8	"■5
2.9	3-i	5-9	7.2	8-9	11.6
3-°	3-2	6.0	7-4	9.0	11.8
31	3-3	6.1	7-5	9-1	11.9
3-2	3-5	6.2	7-7	9.2	12.1
3-3	3-6	6-3	7.8	9-3	12.2
3-4	3-7	6.4	8.0	9-4	12.4
3-5	3-9	6-5	8.1	9-5	12.5
3-6	4.0	6.6	8.2		
  Free Carbonic Acid.—The following process, due to
Pettenkofer, is  taken  from Sutton's " Volumetric Analy-
sis " : 
94
ANALYTIC  OPERATIONS.
  A stoppered  bottle of known capacity, about 150 c.c,
is filled at the source by submergence, or, if taken from a
faucet, by allowing the stream to run in with full force for
some minutes, the nozzle being inserted into  the neck of
the bottle.  Fifty c.c of the water are then  quickly re-
moved by  a pipet, and the  following solutions immedi-
ately added :  Three c.c. of a  saturated solution of calcium
chlorid and 2 c.c. of  a  saturated solution  of  ammonium
chlorid;  45 c.c.  of clear calcium hydroxid  solution of
known strength are added, the flask well corked, the liquids
mixed  and set aside for at least twelve hours, to allow the
calcium carbonate formed to  settle and become crystalline
and  insoluble.   An  aliquot  part (50 to 100 c.c) of the
clear liquid is then drawn off and titrated with decinormal
acid, using phenacetolin or lakmoid as indicator, and from
the amount  required  the  entire  proportion  of  calcium
hydroxid unacted upon can be  determined.    This being
deducted  from  the  amount  originally added,  and the
remainder  multiplied by 0.0022, will give the weight of
carbonic acid in the water in  excess  of that existing as
normal carbonates.
  Boric Acid.—To detect  it, add  to one  liter of the
water sufficient sodium  carbonate to  render it distinctly
alkaline.   Evaporate to dryness, acidify with hydrochloric
acid, moisten a slip of turmeric paper  with the  liquid, and
dry it at a moderate heat.   In the presence of boric acid
the paper will assume  a distinct brown-red tint.

            SPECTROSCOPIC  EXAMINATION.
  For  the  ordinary spectroscopic  examination of a water
a simple apparatus will  suffice.   The  arrangement shown 
TECHNIC EXAMINATIONS.
95
in the cut (Fig. 10) is a small direct-vision  spectroscope,
held in a universal  stand, with an adjustable burner as the
source of heat.
   For  the examination a liter or more should  be evapo-
rated nearly to dryness,
a little hydrochloric acid
being added near the end
of the process, the residue
placed in a narrow strip of
platinum foil, having the
sides bent so as to  retain
the  liquid,   and heated
in the flame.  While this
method will be sufficient
in  many   cases,   a far
better plan  is  to separate
the substance sought for
in a state of approximate
purity and  then examine
with  the   spectroscope.
Very  small   traces  of
lithium,  for   instance,
may be detected as fol-
lows :  To  about a liter
of  the water   sufficient
                                      Fig. 10.
sodium  carbonate is
added  to  precipitate all the calcium  and magnesium, and
the liquid boiled down to about one-tenth its bulk; it is
then  filtered,  the   filtrate rendered slightly  acid  with
hvdrochloric acid, and evaporated to dryness. The residue
is boiled with a little alcohol, which  will  dissolve out  the
 
96
ANALYTIC OPERATIONS.
lithium chlorid.  The alcoholic solution is evaporated to
dryness, the residue taken up with a little water and tested
in the flame.
   In order to identify with  certainty  any line  which may
be obtained, it is only necessary to hold in the flame at
the same time a wire which  has been  dipped in a solution
of the substance supposed to be present,  and to  note
whether the  lines produced by it and the  material  under
examination are identical.

                 SPECIFIC GRAVITY.
   In  the  great majority  of cases the determination  of
specific gravity is not essential.   Ordinary river, spring.
and well  waters contain such small proportions of solid
matter that it is  usually the practice  to take a measured
volume and to assume its weight to be that of an  equal
bulk of pure water.   If the proportion of solids be high, a
determination of the specific gravity may be  desirable.
For this purpose  the specific gravity  bottle  may be used.
This consists merely of a small flask provided with a finely
perforated glass stopper.   The bottle is weighed first alone,
then filled with distilled water at 6o°  F., and finally with
the water under examination at the same temperature.   In
filling the bottle,  the liquid  is first brought to the proper
temperature,  the  bottle completely filled,  the  stopper in-
serted, and  the excess  of water  forced out through the
perforation and around  the sides of the stopper carefully
removed  by  bibulous paper.   The weight  of the  water
examined divided by the weight of the equal bulk of dis-
tilled water  at the same temperature gives the specific
gravity. 
TECHNIC  EXAMINATIONS.
97
  Another method, and one which  gives very satisfactory
results, is by the use of a plummet.   This may conveniently
consist of a piece of  a  thick glass rod of about 10 c.c. in
bulk, or of a test-tube weighted with mercury and the open
end sealed in the flame.  The plummet is suspended to the
hook of the balance  by means of a fine platinum wire and
its weight ascertained.  It is  then  immersed  in  distilled
water at 6o° F., and  the loss in weight noted.   The figure
so obtained is  the weight of a bulk of water  equal  to that
of the plummet.  This having been determined, the specific
gravity of any water  may be found by immersing in it the
plummet and noting  the loss in weight.   This, divided by
the  loss suffered  in pure water, gives the specific gravity. 
   INTERPRETATION  OF RESULTS.
              STATEMENT OF ANALYSIS.

  The composition of water is generally expressed in terms
of a unit of weight in a definite volume of liquid, but much
difference exists as to the standard  used.   The decimal
system is very largely  employed,  the proportions  being
expressed in milligrams  per liter,  nominally parts per mil-
lion ;  or in centigrams per liter, nominally parts  per hun-
dred thousand.  Not infrequently the figures are given in
grains per imperial  gallon of 70,000 grains, or the  U. S.
gallon  of 58,328 grains.  Much more rarely  grains  per
quart, parts per thousand, per cent., or other inconvenient
ratios are employed.   In  this work  the  composition is
always expressed in milligrams per liter.   This ratio is
practically equivalent to parts per million, except in case of
water very rich in solids, a liter of which will weigh nota-
bly more than one million milligrams.   Factors  for con-
verting  the  different ratios are given at the end  of the
book.
  From the analysis of a water it is rarely possible to ascer-
tain the exact arrangement of the elements determined, but
it is the custom to assume arrangements based upon the
rule  of associating in  combination elements having the
highest affinities, modifying this  system  by any inferences
derived from  the character or reactions of the water itself.
                          98 
STATEMENT  OF ANALYSIS.
99
It has been demonstrated that, even in the case of mixtures
of salts producing  no insoluble substances, partial  inter-
change of the basylous and acidulous radicles  takes place.
In a solution of sodium chlorid  and  potassium  sulfate
sodium sulfate  and potassium  chlorid  will be  found,  as
well as the original salts.   When the conditions are ren-
dered more complex by the addition of other substances,
it is obviously impossible to determine the exact arrange-
ment.   In view of these facts, it is preferable to express
the composition of a water by the proportion  of each ele-
ment  or radicle present.  In this way a water containing
K.,S04 will be expressed in terms of K  and  S04, respect-
ively.   In the  case of bodies like  C02 and  Si02, which
may possibly exist  free in the water, their proportion  is
expressed as such.   It frequently occurs that the character-
istics of some of the compounds in a water are sufficiently
marked to indicate their presence, and there can be no
objection to  suggesting, in connection  with  the analytic
statement, the inferences which may thus be drawn.
  The  organic  matters, or derived products,  are best
stated  in  terms of the nitrogen which  they  contain, thus
permitting a  comparison of the different stages of decom-
position.   It is  inadvisable  to represent the amount of
unchanged organic matter  in  terms of  oxalic acid, as has
been suggested, or to express the nitrogen in terms of albu-
min, or any other  supposititious compound.
  The results of  bacteriologic examinations should, as a
rule,  be  reported  as  "points  of microbic  life"  in  the
given  volume of  water.   Many operators, however,  re-
port  the  number of  points as  "colonies"  or even
" bacteria." 
IOO
INTERPRETATION  OF RESULTS.
              SANITARY APPLICATIONS.
  Judgment upon the  analytic results from  a given sam-
ple of  water depends upon  the  class to which it belongs,
and to the particular influences  to which it has been sub-
jected.   A proportion of total solids which would be sus-
picious in a  rain  or river water, would be without signifi-
cance in that from an artesian well.   On the other hand, a
subsoil water of unobjectionable character would contain a
proportion of nitrates  which would be inadmissible in the
case of a river or deep  water.  Location has also much
bearing in the case ;  subsoil waters  near  the sea will  be
found to contain, without invoking suspicion, proportions
of chlorin which would be  ample to condemn  the same
sample if derived from a point far inland.  Hence the im-
portance of  recording, at the time of collection, all ascer-
tainable information as to  the surroundings  and probable
source of the water.
  Analyses of surface waters have little value, unless sup-
plemented by a careful survey of  the watershed to  deter-
mine sources of pollution.  Such survey will often discover
conditions sufficient to  condemn the supply, even though
the analyses may  be satisfactory.   Indeed,  it may be taken
as a fundamental principle that surface water from even
a sparsely populated district will be  unsafe  for use unless
efficiently filtered.
  Color, Odor,  and  Taste.—Water of  the  highest
purity will be clear, colorless, odorless, and nearly tasteless.
While  in some cases a  decided departure from this stand-
ard may give rise  to  suspicion, analytic observations are
necessary to  decide the  point.   Water  highly  charged 
SANITARY  APPLICATIONS.
IOI
 with  mineral matters will possess decided taste, vegetable
 matters  may communicate distinct  color ; but, on  the
 other hand, it may be highly contaminated with dangerous
 substances and  give  no indications to the senses.   Well-
 waters occasionally become offensive  in odor, from pene-
 tration of  tree roots.    The odor  often recalls that of
 hydrogen sulfid.   Sulfids are, indeed, often formed in
 such  cases  by  the abstraction of-oxygen  from sulfates
 under the influence of microbes.  Such waters are often
 used  without apparent injury, but  it is probable that  if
 direct pollution occurs, the danger would be enhanced  by
 the presence of the  vegetable matter.    Miquel has de-
 scribed a bacillus, under the name B. sulfydrogenus,
 which produces  hydrogen sulfid  readily.  Some  of the
 common  putrefactive  bacilli  doubtless  have  this power
 also,  largely through  the  influence of the hydrogen  lib-
 erated by them.  In  waters containing hydrogen sulfid,
 species of  beggiatoa,  especially  B.  alba,  thrive,  and,
 decomposing the sulfid, become impregnated  with sulfur.
 Natural sulfur waters frequently contain these organisms,
 as do,  also,  waste-waters containing sulfid.
   Surface waters collected in reservoirs  or ponds often
 become very offensive from the growth of  algae, but apart
 from the disgust created by the water, it is  not  known that
 any harmful results occur to those  using it.
   Turbidity  may be  due  to  several  causes, of  different
degrees of danger, but is always objectionable.
   Total  Solids. — Excessive  proportions  of  mineral
solids,  especially of marked physiologic action, are known
to render water  non-potable, but  no  absolute maximum
or minimum  can  be  assigned as  the  limit  of  safety. 
102
INTERPRETATION OF RESULTS.
Distilled water  and waters  very highly charged with min-
eral  matter have been  used for long  periods without  ill
effects.   The popular notion that the so-called hard waters
conduce to the formation of urinary calculi is not borne
out by surgical experience  or  statistical inquiry.  Many
urinary  calculi are composed  of  uric  acid, and are  the
results of disorders of the general  nutritive functions.
   Sanitary authorities have fixed an arbitrary limit of total
solids of about six hundred parts per  million, but many
artesian waters in  constant use exceed this.  An instance
is found in the well on  Black's Island, near Philadelphia,
given  in the table of  analyses,  which  contains  nearly
twelve  hundred parts per  million, is very  agreeable  in
taste, and has  been in  constant use for some years by a
number  of persons without injury.   The  assertion that
water to be wholesome  must contain an  appreciable pro-
portion of total solids is also not demonstrated by clinical
experience.  A discussion  of the effects of special mineral
ingredients—e. g.,  magnesium sulfate, ferrous carbonate,
etc.—belongs to general therapeutics.
   The odor produced on heating the water residue is often
of much use in detecting contamination.   Odors similar
to those produced by heating glue, hair, rancid fats, urine,
or other animal products, will give rise to grave suspicion.
On the other  hand, a  more favorable judgment may be
given when the odor recalls those given off in the heating
of non-nitrogenous vegetable materials, such as wood-fiber.
   Poisonous Metals.—The proportion of iron in water
 constantly  used for drinking  purposes should not much
 exceed  three parts per million.   Lead,  copper, arsenic,
 and zinc must be considered dangerous  in any amount, 
                SANITARY  APPLICATIONS.             103

though it appears that zinc and copper, being least cumu-
lative, are rather less objectionable in minute amount than
the others.  Concerning the limit of safety with mangan-
ese and chromium very little is known, but their presence
in appreciable quantity must be looked upon with suspicion.
   Chlorids  and  Phosphates.—Chlorids—principally
sodium  chlorid—and phosphates are abundantly  distrib-
uted in rocks and  soils, and find their way into  natural
waters ; but while the former are freely soluble and remain
in undiminished amount under all conditions to which the
water is subjected, all  but  minute amounts of the  latter
are either precipitated or removed by the action of living
organisms.  Surface and subsoil waters  ordinarily  contain
but a few parts per million.  Both chlorids  and  phos-
phates being constant  and  characteristic ingredients  of
animal excretions, it is obvious that  an  excess  of them  in
natural waters, unless otherwise accounted for, will suggest
direct contamination.   Proximity to localities in which
sodium  chlorid is abundant, such as the sea-  or  salt-de-
posits, will deprive the figure for the chlorin of diagnostic
value, nor can any indication of sewage or other  danger-
ous pollution be inferred from high proportion of chlorin
in deep waters.  Further, it has been shown that the pro-
portion  of chlorin  in  uncontaminated waters is tolerably
constant, while in  water subjected to  the  infiltration  of
sewage the chlorin undergoes marked variation in amount.
In most cases, therefore, a  correct judgment can  only be
attained by comparison with the  average character of the
waters of the same type in the district, and by examination
at intervals of the water in question.
   As  regards  phosphates,  Hehner, who has published a 
104
INTERPRETATION OF  RESULTS.
series of analyses, states that the presence of more than 0.6
part per million—calculated as P04—should  be regarded
with suspicion.  On the other hand,  the absence of phos-
phates affords no positive proof of the freedom from pol-
lution.
  Nitrogen from Ammonium Compounds.—Ammo-
nium compounds are usually the results of the  putrefactive
fermentation of nitrogenous organic matter ; they may also
be the  product of the reduction of nitrites and nitrates
in presence of excess of  organic matter.  In  either case,
therefore, they suggest contamination.   Deep  waters often
contain an excess  of ammonium compounds, derived, in
large part, from the reduction of nitrates.   Their presence
here is hardly ground  for  adverse  judgment,  since  the
water, even though originally contaminated, has undergone
extensive filtration and oxidation, its  organic matter con-
verted into bodies presumably harmless, and microbes have
perished.  Such waters, indeed, usually show  only traces
of unchanged organic matter.
  Rain water  often contains large  proportions of ammo-
nium compounds ; but here, also, the fact can not condemn
the water, since  it does  not indicate contamination with
dangerous organic  matter.
  The evolution of ammonia in the distillation of rainwater
often continues indefinitely,  the larger portion passing over
in the first distillates, but small quantities being present
even after the  distillation has been much prolonged.  The
same continuous evolution of  ammonia is noted in waters
containing urea, but in  this case a larger proportion is
collected in  the earlier distillates, nearly all coming over
before one-half the water has been distilled. Fox gives the 
SANITARY  APPLICATIONS.
io5
following figures as ratios obtained in the analysis of two
samples, one of rain water collected from a roof and there-
fore impure, and the other of a water containing urine :
Rain Water.			Urine Water.
1st distillate, .	• • 0.35	0.38	parts per million
2d	. . 0.25	0.14	"
3d	. . 0.12	0.065	it n
4th "	. . 0.09	0-035	" "
5th «	. . 0.09		<< n
6th	. . 0.04		a a
7th "	. • 0.03		u a
0.97
0.62
   Nitrogen by Alkaline Permanganate (Nitrogen of
"albuminoid  ammonia").—A large yield  of ammonia
by boiling with  alkaline potassium permanganate  will, of
course, point to  an excess of nitrogenous organic matter.
The inferences  to be drawn depend upon the origin and
condition of the organic material.   If animal, the water
may at once be condemned as unsafe.  Waters containing
excessive  amounts even  of vegetable matter are not free
from objection, since  they have frequently caused  persis-
tent diarrhea.   If the organic matter, whether  animal, or
vegetable,  is  in a  state of  active decomposition, it is
doubly objectionable.   Mallet has called attention to  the
fact  that  such waters, as a rule, yield ammonia rapidly,
whereas non-decomposing material  yields it  but  slowly,
and he points out the importance,  therefore, of noting  the
rate at which the ammonia collects in the distillate.
  Dr. Smart has observed that water containing fermenting
vegetable  matter is colored yellow  by boiling with  sodium 
106          INTERPRETATION  OF RESULTS.
carbonate,  and that when Nessler reagent is added to the
distillate, a greenish, in place of the  ordinary yellowish-
brown, color is produced.   He applies  this fact in  con-
junction  with the determination of the oxygen-consuming
power (Tidy's  process) and the rate of evolution of the
ammonia by alkaline permanganate as follows :
  A water  yielding ammonia slowly by alkaline perman-
ganate contains recent organic matter ;  of  animal deriva-
tion, if the oxygen-consuming power is low; of vegetable,
if high.
  A  water yielding ammonia more  rapidly  by  alkaline
permanganate,  shows  decomposing  organic matter;  of
animal origin,  if the oxygen-consuming power be low and
there be no interference with  the  Nessler reaction ;  of
vegetable origin, if the oxygen consumed be high, and if
a yellow color  be  produced in  the water by sodium car-
bonate,  and a greenish color in the nesslerized distillate.
  Inferences as to the source of the organic matter can
usually be drawn from the amount of chlorin and nitrates
present.   If the chlorin be high,—i.  <?., in excess of the
average of the  district,—it  may be inferred that the mate-
rial is, in great part, of animal origin.   In this case the
nitrates will either be high or  entirely absent, according as
the contaminating matter has passed through soil or enters
the water directly.
  A large amount of vegetable matter will,  as a rule,  show
itself by the color it imparts to the water.
  Wanklyn gives the following standards :
      High purity,.........o.oo to 0.041 per million.
      Satisfactory purity,.......0.041 to 0.082  "    "
      Impure,............over 0.082. 
SANITARY  APPLICATIONS.
107
In  the  absence of ammonium  compounds,  he does not
condemn a water unless the nitrogen by permanganate ex-
ceeds 0.081 per million ;  but a water yielding 0.123 parts
per  million of  nitrogen  by permanganate he condemns
under all circumstances.
  Total  Nitrogen.—Drown and  Martin's results with
surface waters  indicate that the total nitrogen obtained by
their process is about twice that obtained by alkaline per-
manganate.  The experiments made by Dr. Beam and my-
self  accord with  this.   Further observation  on  different
waters and by different observers will be required to de-
termine the value to be  assigned to the figures obtained
by  this  method.  This method is  especially suitable for
studying the  effects of filtration,  storage,  etc., on the
nitrogenous organic matter in water.
  Nitrogen  as Nitrites.—Nitrites are present in water
as the result either of incomplete nitrification of ammo-
nium, or the  reduction of already formed nitrates, under
the influence of reducing agents or  microbes.   Since they
are transition  products, their  presence in water is usually
evidence of existing fermentative changes,  and,  further,
may be taken as  indicating that the water  is unable  to
dispose  of the organic contamination.   When, however,
the conditions are such that oxidation can not take place,
nitrites  may  persist  for  a long time.   This sometimes
occurs in deep waters in which fermentative changes have
long since ceased, but oxygen is  not available.  These
contain not  infrequently small  amounts of nitrites,  to
which the same degree of suspicion can not be attached.
When nitrites are found in these waters, the  possibility of
their introduction  from  polluted subsoil water,  through 
io8
INTERPRETATION OF RESULTS.
defective tubing, must not be  overlooked.   Rain water,
also, sometimes contains nitrites derived from the air, and
therefore not indicative of any putrefactive change.   The
presence of measurable quantities of nitrites  in  river or
subsoil water is sufficient ground for condemnation.
  Nitrogen as  Nitrates.—Nitrates are the final point
in the oxidation of  nitrogenous organic matter, especially
animal  matters.  Rain  water  and that from mountain
streams  and  deep  wells,  except from  cretaceous strata,
generally contain only traces, but river and subsoil waters
will  always  contain appreciable amounts, unless some re-
ducing action, such as recent sewage-pollution, is at work.
When, therefore, a  water contains enough mineral matter
to demonstrate its  percolation through  soil,  and at the
same time is free  from nitrates or contains only traces, the
occurrence of a destructive fermentation may be inferred.
These cases are  not  uncommon  among well-waters, and
the  samples are generally turbid  from suspended  organic
matter.   Decided  departure,  either  by increase  or de-
crease, from  the  proportion of nitrates usual in the same
class of water in any district may be taken  as  evidence of
contamination.
  Oxygen-consuming  Power.—Sanitary authorities
differ very much as  to  the  significance  of this  datum.
Attempts  have been  made to fix maximum limits for  the
various  types of water,  and  also to  gage  the  character
and condition of the organic matter by observing  the rate
at which the oxidation takes place, but no positive  con-
clusions can be given.   In general, it may be said that  a
sample which has high oxygen-consuming power will be
more likely  to  be unwholesome than  one which  is low in
this  respect; but the interferences are so  numerous, and 
SANITARY APPLICATIONS.
109
the susceptibility to oxidation of different organic matters,
of even the  same type, is so different, that the method is
at best only of accessory value.  It is  especially suitable
for consecutive determinations on the same supply.
   The following proportions are given by Frankland and
Tidy as  the basis of  interpreting  the  results of  this
method :
                       Oxygen Absorbed in Three Hours.
      High organic purity.....0.05     parts per million.
      Medium purity,......0.5 to 1.5 "  "    "
      Doubtful,.........1.5 to 2.1 "  "    "
      Impure,......over 2.1       "  "    "

   For the  method with  acidified   permanganate  at  the
boiling heat, the German chemists,  who employ it largely,
regard an absorption of 2.5 parts  of oxygen per million
as  suspicious, and  some sanitary authorities have fixed 3.8
parts of oxygen per million as the highest permissible limit.
   Dissolved Oxygen.—Full aeration of water is favor-
able to the destruction  of organic matter; a decided dimi-
nution in the quantity of dissolved oxygen may show excess
of such matter and of microbic life.   Gerardin has pointed
out that this diminution is associated with the development
of low forms of vegetable  life, and  Leeds has recorded
similar facts.   These changes are more likely to take place
in  still waters, and  are frequently accompanied  by  dis-
agreeable odor and taste.  In cases  in which stored waters
become unpalatable, these facts should be  borne in mind.
   Dupre  has given the following as the basis for interpret-
ing the results of his adaptation of the determination of
dissolved oxygen :
   " A water which does not  diminish in its degree of aera-
 ion during a given period, may or may not contain organic 
no
INTERPRETATION OF RESULTS.
matter, but presumably does not  contain  growing organ-
isms.   Such organic matter as it may be found to contain
by chemic analysis need not be considered as dangerous
impurity.
  " A water which, by itself, or after the addition of gela-
tin or other appropriate cultivating matter, consumes oxy-
gen from the dissolved air, at lower temperatures, but does
not consume  any after  heating  for,  say,  three  hours  at
1400 F., may be regarded as having contained living  or-
ganisms, but  none  of a kind  able to survive exposure to
that temperature.
  " A water which,  by  itself, or after addition of gelatin
or the like, continues to  absorb  oxygen from the contained
air after heating to 1400 F., may be taken as containing
spores or germs able to  survive that temperature."
  Hardness.—The degree of hardness, unless very high,
has but little bearing on the  sanitary value of water,  but
is important in reference to its use for general household
purposes, in view of the soap-destroying power which hard
waters possess.
USUAL ANALYTIC RESULTS FROM UNCONTAMINATED WATERS.
                   Milligrams per Liter.
	Rain.	Surface.	Subsoil.	Deep.
Nitrogen by perman-Nitrogen as NH4, . . . " " nitrites, . . " " nitrates,. .	5 to 20 Traces to i 0.08 to 0.20 0.20 to 0.50 'None or traces Traces	15 upward 1 to 10 0.05 to 0.15 0.00 to 0.03 None 0.75 to 1.25	30 upward 2 to 12 0.05 to O.IO 0.00 to 0.03 None 1-5 to 5	45 upward Traces to large quantity 0.03 to O.IO Generally high None or traces 0.00 to 3
 
SANITARY  APPLICATIONS.
I I I
  Inferences from Culture-Methods.—Owing to the
great differences in the conditions and manner of growth
in various species of microbes, the inferences to be drawn
from the cultivation of the germs present in a water sample
are  uncertain.   In spite of the study which has been given
to the subject, the differentiation of  specific forms has not
reached exactness, nor have the conditions most favorable
to growth  been ascertained.   Different  observers  pursue
different methods of culture, and the results are not com-
parable.   Broadly speaking, the examination of the bacte-
rial life in  water may include two inquiries,—a simple cal-
culation  of the number of individual living microbes, and
the  detection of the presence of certain specific forms.
Even the first of these objects, though simple, can not be
carried out with absolute certainty at the present day.  The
number  of microbes in water is subject to  rapid  increase
for a brief period after  collection of a sample, and  may
be  greatly modified by incidental conditions during stor-
age or transportation, so that  little value can be attached to
quantitative  determination, except when  made promptly
The culture-fluids ordinarily used, and the conditions  in
which the  culture takes place,  do not suffice for the devel-
opment  of all  the forms  present.   The  cultivation ought
to be extended  over many days, and samples of the water
tried with various nutritive media and at different tempera-
tures to  secure a knowledge of the forms  present.  As an
indication of the insufficiency of  the common methods,
it may be  mentioned that Miller describes six species of
microbes occurring in  the  human  mouth,  none of which
would grow  on  any form of culture-medium which he was
able to produce. 
112          INTERPRETATION  OF RESULTS.

  It is necessary that any record  of bacteriologic  exami-
nation of water should include a precise statement of the
conditions of cultivation.  That  is, composition  of the
culture-medium ; if alkaline or  acid, the degree  of this
reaction expressed in terms of some standard solution ; the
temperature at which the cultivation takes place, and the
time.  It is not correct to record the number of individual
colonies  observed on the culture-field as indicative of so
many living microbes,  for in some cases two  or more
microbes may have been jointly concerned in the formation
of a colony.  A proper method  is  simply  to enter the
observation as so many points of  microbic life, and to add
whatever detailed description is necessary.  Some progress
has been  made  in  the United  States toward securing a
satisfactory method of microbe-counting, with a view to
adopting  it as  a uniform system, in order that results in
some degree comparable may be  obtained  by  different
observers.   There is still, however, much irregularity in
the details as carried out by leading bacteriologists.
  In the determination of specific forms,  far  greater diffi-
culty arises, and, unfortunately,  this difficulty  concerns
especially  the great problem  which  is presented to the
sanitary chemist—namely, whether a given water-supply is
likely to produce disease.  The recognition of so  charac-
teristic a form as the comma bacillus in water is not very
difficult, but it is a problem rarely presented to those chem-
ists who are practising in civilized countries.   The history
of the attempts to determine bacilli of objectionable char-
acter in water has  presented  a  continuous  evolution, in
which a degree of confidence existing at one time has been
overturned by later discoveries.   It was first thought that a 
SANITARY  APPLICATIONS.
IJ3
distinction might be made between ordinary water-bacteria
and sewage-bacteria, by reason of the action of the latter
upon  the gelatin  culture-medium.  Some  bacteria grow
without altering the condition of the gelatin visibly ; others
rapidly digest it and produce  a liquid  peptone.   It was
supposed  that  these latter  were  the  more objectionable
forms,  and some chemists  still record the  liquefying
microbes as "sewage-microbes."  This distinction is, how-
ever,  untenable.   Several bacilli known to be associated
with intestinal discharges do not produce any liquefaction,
while some that are harmless rapidly liquefy.
   The  method  used  in  the Hygienic Laboratory of the
University of Michigan has the sanction of  high authority
and the benefit  of extended experience, but it is doubtful
if it  meets the requirements of the sanitary  chemist.
However general the acceptance of the method by physi-
ologists, it can.  not be considered safe to infer that germs
which are poisonous when injected subcutaneously or intra-
abdominally into  rats, guinea-pigs, rabbits, and mice, are
necessarily dangerous in water consumed in the  ordinary
way by human beings.   Tests of this kind require the very
highest skill and facilities, involve great expense and delay',
and it is probable that in a large majority of  cases a careful
analysis upon the lines generally accepted will afford as safe
a ground for inference as this elaborate method.   It is not
impossible that  treatment  at blood-heat and in a highly
stimulating nutritive medium may materially increase the
virulence of some microbes.
   There is, however, one field  of inquiry in which even
mere microbe-counting has value, and that is in comparing
samples of the same water before  and after some treatment
       h 
H4
INTERPRETATION  OF RESULTS.
or other incident.   In these studies  the  method is  suffi-
ciently free  from fallacy to make the results trustworthy
when they are conducted  in  a strictly uniform  manner;
thus, if a river water supplied to a filter be studied  daily
by examination of repeated samples before and after filtra-
tion, inoculating separate  portions  of the same culture-
medium, and  multiplying the results to such an extent as
to eliminate accidental differences, a comparison between
the water before and after filtration may be safely made as
to the  proportion  of  microbes removed.   Moreover, spe-
cial microbes of highly  characteristic properties may be
introduced in large quantities into the water, and by sub-
sequent culture the extent to which these are removed may
be satisfactorily recognized.  Thus,  in the extended ex-
periments of the Massachusetts State  Board of Health the
Bacillus  prodigiosus was  employed as a  test-microbe, its
chromogenic power enabling  it to be detected with  great
facility.   It is said in these reports that the life-history and
habits of  this microbe are so  nearly identical with that of
the B.  typhosus that it is conveniently substituted for  the
latter in such  test  experiments.   B.  typhosus of most ob-
servers refers to  a microbe  cultivated  from blood and vis-
cera of patients dead of typical typhoid fever.  Proof of the
existence of a distinct, differentiated, specific form, which
is the sole and only cause of the fever, is still lacking.  The
old method  of recognizing the B. typhosus, by cultivation
on potato, was never  regarded as very satisfactory, and is
now known  to be valueless.  Research has indicated that
several common water-bacteria may assume temporary con-
ditions known as " involution forms," in which they may
have functions different from those ordinarily belonging to 
SANITARY  APPLICATIONS.             115
them.  Among the bacilli that seem to be closely associated
with those forms that have been designated as B. typhosus,
is one which is extensively present in the intestinal contents
of man and the domestic animals, and  which is designated
as the B.  coli communis.  It is abundantly present in water
which has received any form of sewage,  even when that is
merely surface-washings.  It is not necessarily associated
with danger to those drinking  the water, but its presence
must be regarded as suspicious.   It has undoubtedly been
designated as B. typhosus in many cases, and  we now know
enough of the errors of this  class  of  investigation to say
positively that a large proportion of the earlier  literature
on  this subject  is without value.  Since it  appears that
B.  coli communis is the germ most likely to be confounded
with the specific typhoid-causing germ, if such  exists, the
efforts of observers have been  directed toward  indicating
the specific differences  as  clearly  as  possible.   Unfortu-
nately, these differences appear  to be entirely negative as
to the more important form, rendering its detection in the
presence of the more positive form impossible.  A  com-
petent American writer has recently stated that " between
what we may regard as typical forms  of the B. coli com-
?nunis,  on the  one hand,  and  typical  forms  of the  B.
typhosus,  on the other, there is a whole series of intestinal
bacilli known under various names and described by vari-
ous bacteriologists,  representing a perfect  gradation  from
one microbe to  the other."  In many cases  in which a
mixture of B. coli communis and B. typhosus is cultivated,
the former rapidly overgrows and extinguishes or conceals
the latter.
   Another water microbe that has ordinarily  no signifi- 
Il6          INTERPRETATION  OF RESULTS.
cance of danger is the B. fluorescens liquefaciens, but the
observations of Moore (Bureau  of Animal  Industry, No.
3), show that  cultures of this microbe suddenly take on
septic properties and lose them again subsequently.
  Vaughan has expressed himself in writing as follows in
regard to the specificity of B. typhosus :
  "Of one thing  I  am  certain,  and  that is that  I  am
ignorant of any crucial test, or of any combination  of
tests, upon the strength of which I can say at  present that
a germ which I may find in drinking-water is identical with
the so-called typhoid bacillus.   I have found  in spleens,
after death from typhoid  fever, germs which  differ from
the typhoid bacillus obtained from Berlin,  and from one
another as markedly as ray^. venenosus differs from either
or both."
  All sanitary evidence is to the effect that the water-sup-
ply of  Philadelphia is constantly infected with  the  germ
of typhoid fever, yet  the  bacteriologists of  the  city, who
are distinguished workers, have never  found the typical
germ in that water.

            ACTION OF WATER ON LEAD.
  The almost universal use of  lead  pipes  for conveying
water,  and the facility with  which  some waters corrode
and dissolve the metal,  make it a question of moment to
determine the cause of this action and to devise means for
its  prevention.  The  subject has  received considerable
attention within the last few years, and the conditions which
determine corrosion are now fairly understood. As a rule,
it is found that waters free from mineral matter dissolve
lead with facility,  especially  in the presence of oxygen. 
ACTION  OF WATER ON  LEAD.
117
Some very  soft waters are entirely  without action, and
this was unexplained  until a few years ago, when Messrs.
Crookes, Odling, and Tidy found that the action was con-
trolled by  the amount  of silica contained in the water.
They found that those soft waters which, when taken from
the service  pipes, contained  a notable  quantity of lead,
gave, on the average, three parts of silica per million ;  in
those in which there was no lead, the  silica  present
amounted to 7.5 per  million, and in those in which the
action was intermediate,  5.5  parts per  million.   That it
was  really  the  silica that conditioned  the corrosion was
confirmed  by laboratory  experiments.   They also  found
that the most effective way of silicating a water is by passing
it over a mixture of  flint and limestone.  The reason for
this was pointed out later  by  Messrs. Carnelly and  Frew,
who showed that while calcium carbonate and silica both
exert a  protective  influence,  calcium  silicate  is   more
effective than either ; and, further, that  in almost all cases
in which corrosion took place,  it was greater in the presence
of oxygen.   This is  particularly the case with potassium
and  ammonium nitrates and with calcium hydroxid.  The
reverse is true of calcium sulfate, which  is  more corrosive
when air is excluded.   Their experiments  also show that
the  presence of calcium  carbonate or  calcium silicate,
altogether prevents corrosion by potassium and ammonium
nitrates.
   As the result  of an elaborate series of  experiments, Miil-
ler concludes, that  while chlorids,  nitrates, and sulfates
all act upon  lead pipes, no corrosion  takes  place in the
presence of sodium acid carbonate, and that calcium car-
bonate, by taking up carbonic acid, acts in the same way. 
Il8          INTERPRETATION OF RESULTS.

This latter conclusion is at variance with the observations
of Carnelly and Frew, who found that calcium carbonate
is equally effective when carbonic acid is excluded.   Mul-
ler also states that surface waters, contaminated by sewage
and containing large amounts of ammoniacal compounds,
will dissolve lead under all circumstances.
  Allen  has  shown  that water  containing  free acid,  in-
cluding sulfuric acid, acts energetically upon lead.  This
is not  surprising  in view of the later experiments, which
prove  that even  calcium sulfate is corrosive.   Later,  W.
Carleton-Williams found that even in the presence of free
acid, corrosion may be prevented by the addition of suffi-
cient silica.   His experiments also confirm the view gener-
ally held, that soluble phosphates protect lead to a marked
degree.
  The following is a summary of the more important  ob-
servations on this subject:
  Corrosive : Free acid or alkalies, oxygen, nitrates, par-
ticularly  potassium and ammonium nitrates, chlorids, and
sulfates.
  Non-corrosive and preventing corrosion  by the  above :
Calcium  carbonate,  sodium  acid  carbonate, ammonium
carbonate, calcium silicate, silica, and soluble phosphates.
  It is said  that  filtration through animal charcoal is a
means of removing  the greater portion of any lead sus-
pended or dissolved  in the water.   Such filters must be
attended to and renovated  from time to time.

               TECHNIC APPLICATIONS.
  Boiler Waters.—The main conditions affecting  the
value  of a  water for  steam-making  purposes  are   its 
TECHNIC APPLICATIONS.             119
tendency to cause corrosion and  the  formation of scale.
Corrosion may be  due to the water itself,  to the presence
of free acids, or to substances which form acids under the
influence  of the heat to which the  water is subjected.
Pure  water—e. g.,  distilled water—exhibits a  powerfully
corrosive action upon iron.   The  dissolved oxygen which
all waters contain also aids in the corrosion, and especially
when accompanied, as is usually  the case, by carbonic
acid.   There  is always  greater rusting at the point at
which the water enters the boiler,  since there the gases are
driven out of solution and  immediately attack the metal.
This  is an evil  that obtains with all waters, and it is not
customary, in making examination for technic purposes,
to determine the amount of these bodies.  In water that
has had free  access to  air, the oxygen in solution is a
tolerably constant quantity, and it is sufficient to note the
temperature and refer  to the table of amounts of oxygen
dissolved in water.  The corrosive action  of oxygen and
carbonic acid  is especially noticeable in  waters  that are
comparatively pure, such as those derived  from mountain
springs.   This was  repeatedly  observed by  Dr. William
Beam, in  the  examination of the waters used  for the
locomotives  of the  Baltimore and Ohio  Railroad.   The
waters which caused the  most corrosion were mainly those
containing small quantities of solid matter, the full amount
of oxygen, and considerable carbonic acid, but no other
acid  or acid-forming body.
   Free acid, other than  carbonic  acid, is not  often found
in water, and if present, renders  the  water unfit  for use,
unless it be neutralized.   Mine waters are the most likely
to  contain  [free  acid,  sulfuric  acid  being  generally 
120
INTERPRETATION OF  RESULTS.
present.   Sometimes  the acidity is due to organic acids.
These  act  very injuriously on iron.  Allen gives an  ex-
ample of this in the water supplied to Sheffield, England,
which  he found to contain  an  organic acid  in amount
equivalent to  from 3.5  to 10 parts of sulfuric acid  per
million.
  Magnesium  chlorid is frequently present in waters, and
if in considerable  quantity may be very  harmful.   At a
temperature of  3100 F.,  corresponding to an effective
pressure  of four atmospheres,  magnesium chlorid reacts
with water to form magnesium oxid and hydrochloric acid,
the latter attacking the boiler, especially at the water-line.
If there be present at the same time considerable calcium
carbonate, the evil may be somewhat lessened, but, as Allen
has pointed out, and  as we also have  noticed, there  may
still be corrosion, so that the  presence of more than a small
quantity of the salt, say a grain or two  to the gallon,  may
be  considered objectionable.   Allen  remarks that  the
presence  of a certain  amount of sodium  chlorid  may
prevent  this decomposition,  the  two chlorids combining
to form a stable double  salt.   The addition, therefore, of
common salt to a water containing magnesium chlorid may
act to diminish corrosion, a point which will bear  further
investigation.
  It has  not  been determined  how far the presence of
nitrites,  nitrates, and ammonia affects the quality of water
for steam-making  purposes;  but it is more than probable
that they act harmfully, especially  the nitrates, which are
frequently present in  large amount.
  Scale is composed of  matters deposited from the water
either  by the  decompositions induced  by the heat or by 
TECHNIC  APPLICATIONS.
121
concentration.   When the deposit is  loose, it is termed
sludge or mud, and usually consists of calcium carbonate,
magnesium oxid, and a small amount of magnesium  car-
bonate.  The magnesium oxid is formed by the decompo-
sition of the magnesium carbonate and chlorid.  This fact
was first pointed out by Driffield.
  The formation of sludge is the least objectionable effect,
since it may readily be removed by "blowing off,"  pro-
vided that care is previously taken  to allow the flues to
cool down so that when the water is removed the heat of
the flues may not bake the deposit to a hard mass. Waters
containing calcium  sulfate  form hard incrustations diffi-
cult to remove and causing great loss of fuel by interfering
with the  transmission of  the  heat  to the  water.   It not
only forms a hard incrustation in itself, but becomes in-
corporated with the  mud, and renders it also hard.   The
hard scale will  also contain practically all the silica and
the iron and  aluminum present in the water, besides any
matters originally held in suspension.
  It follows from the above that a water only temporarily
hard will, if care is taken  in the management of the boiler,
cause the formation merely of a loose deposit of sludge—
temporary hardness being due in the main to calcium and
magnesium carbonates.   A  water permanently hard  will
probably form a hard scale,  since such hardness is usually
due to calcium  sulfate.
  In accordance with these  principles, the analysis of a
water for steam-making purposes may  include  the  deter-
minations of free acid, total solid residue, S04, CI,  Ca, Mg,
temporary and  permanent hardness.   In  cases in  which
the qualitative tests show  but small  amounts of  S04 and 
122          INTERPRETATION OF  RESULTS.

CI, the analysis may be limited  to the  determinations of
the temporary and permanent hardness.
   In the laboratory of the Pennsylvania Railroad  an ap-
proximate determination of scale-forming ingredients  is
made in the following manner:  The total solids obtained
by evaporation are treated with  diluted alcohol (fifty per
cent.), and the undissolved residue is denominated " scale-
forming material."
   It has been pointed out in an  earlier  chapter  that it  is
not possible to deduce from the analytic result the exact
forms in which  the  various elements are combined, but
since it  is known that at the high  temperature ordinarily
reached in boilers definite chemical changes  occur, it  is
safest to exhibit  the maximum  amount of corrosive  and
scale-forming ingredients which  the water under these cir-
cumstances  could develop.   Thus, since calcium sulfate
is  practically insoluble in water  above  2120 F., the pro-
portion  of calcium  sulfate  may be regarded as such  as
would be formed by  the total quantity  of calcium or the
total quantity of S04, according  to which is present in the
larger amount.   Similarly, as the decomposition of magne-
sium  chlorid is  induced by the high temperature of the
boiler, the analytic statement  should  indicate the maxi-
mum proportion of this  compound obtainable from the
magnesium and chlorin present.  These  rules can not apply
absolutely to waters rich  in alkali  carbonates, since  these
would neutralize any acid formed from the magnesium
chlorid, or even prevent its formation, and would prevent,
to a large extent, the formation of calcium sulfate.  Much
remains  to  be  determined concerning  the  effects of the
high temperature and concentration to which boiler waters
are subjected. 
           PURIFICATION OF  DRINKING  WATER.       123

  General Technic Uses.—In regard to the quality
of water for technic other  than steam-making purposes,
such as brewing, dyeing, tanning, etc., no detailed meth-
ods or standards can be laid down.   The nearest approach
to purity that can be secured in the supply will be of the
greatest advantage.   The more objectionable qualities will
be large proportion of organic matter, especially if it dis-
tinctly colors  the water, excessive  hardness, and notable
amounts of iron or free mineral acid.   It is said that one
part of iron per million will render water  unsuitable for
bleaching establishments.  It has been noted that a large
proportion of active microbes is injurious in the manufac-
ture of indigo.  In artificial ice making, a very pure water
must be used if a clear and colorless product be desired.
Any suspended or dissolved coloring-matter will be  con-
centrated by the freezing and  appear in  the bottom or
center of  the mass.
  The examination  of sewage-effluents  and waste waters
from manufacturing  establishments  is  to  be  conducted
upon the  same principles as  for  ordinary  supplies,  but
especial attention must be given to the presence of poison-
ous  metals  and free mineral acids.  The  latter interfere
with the normal self-purification  of  the water.  For the
nitrogen determination, the Kjeldahl  process will be found
more satisfactory than that by alkaline permanganate.

        PURIFICATION OF  DRINKING WATER.
  The most obvious method of purifying water is by dis-
tillation.   The process is too expensive for general use,
but  is  especially adapted for water intended for pharma-
ceutic  or  analytic purposes.   It has also  been  used for 
124          INTERPRETATION  OF RESULTS.

supplying vessels at sea and in tropic localities in which
the natural waters may be contaminated with malarial or
other germs.   The  majority of microbes are  killed  by
short exposure to a temperature of 2120 F.;  hence, water
may be  purified, on  a  small   scale,  by simple  boiling.
Freezing does  not  have  the same effect, many microbes
retaining vitality for a long time in ice, and even at very
low temperatures.
   The self-purification of water—that is, the destruction of
organic matter and pathogenic  microbes, by  reason of  the
development of the ordinary microbes of putrefaction—
occurs satisfactorily only  in alkaline  waters, hence, acid
effluents check this process.  The addition of lime in suffi-
cient amount to give  a  slightly alkaline reaction will be
beneficial.
   The conditions necessary to secure self-purification of
surface waters are not  fully understood, and  it is unsafe to
state that a polluted stream will purify itself in any given
distance.   It must  also be remembered  that the dilution
of infected sewage by its introduction into a large volume
of uninfected water will  assist,  for a time at  least,  the
multiplication of pathogenic microbes.
   The  methods in general use  for  purifying  water  are
simple filtration and the removal of the impurities by ap-
propriate chemical agents.
   Filtration.—For household purposes forms  of carbon,
stone, and sand filters are used, which yield  clear filtrates,
but  permit, sooner or  later, the transmission of microbes.
The suspended matter in  the water gradually accumulates
on the surface of the filter, and causes a great  increase in
the number of the  microbes, some species of which appar- 
PURIFICATION OF  DRINKING  WATER.
X?5
ently grow through the  pores of the filter, and are carried
into the  filtrate.   The following  are among  the more
efficient forms of household filters :
  Bischof Spongy-iron  Filter.—The construction of this
is shown  in figure  n.   The spongy iron  is  obtained by
reducing hematite,  at a temperature below the fusing-point
of iron.
  It rests on a layer of pyrolusite (manganese dioxid),
below which is an asbestos bag  having
a short   tube  with  perforated  cap.
This is a very efficient form, removing
much of the dissolved organic matter,
and practically  all  the  suspended
matter, including the microbes.
  Chamberlain-Pasteur  Filter.—This
consists of tubes of unglazed biscuit-
ware, the number  depending  on the
size and required delivery of the filter.
There are arrangements for continu-
ous filtration by attaching the tube to
the  faucet;  also  forms adapted  to
simultaneous cooling and  filtration.
The  observations  of  Pasteur and
others  have  shown  that  this  is  a
highly efficient filter, yielding for a considerable  time  a
filtrate entirely sterile.  It requires occasional cleaning,
since, after continuous use, the microbes may pass through
the pores, probably by a  process  of growth.  An occa-
sional boiling of  the  tubes in water would be sufficient to
overcome this  difficulty.  The Berkefeld  filter is  of this
type.
Fig. ii. 
126          INTERPRETATION  OF RESULTS.

  Many other forms of filters have 'been devised.  Com-
prehensive comparative tests show that, except as to those
based on  the principle of  the Chamberlain-Pasteur filter,
but little time elapses before the filtrate contains numerous
microbes.
  For the purification of water  on the large scale the value
of sand filters has been so  thoroughly  established that the
method needs  no further  discussion.   The construction
and  operation  of these  filters are engineering questions
entirely.
  Precipitation Methods.—The observations of  Dr.
P. F. Frankland and others have established the following
points :
   " Organized matter  is, to a  large and sometimes  to a
most remarkable extent, removable from water by agita-
tion with suitable solids in a  fine state of division, but
such methods of purification are unreliable.
   " Chemical precipitation is attended with a large reduc-
tion in the number of microorganisms  present in the waters
in which  the precipitate is made to  form and allowed to
subside.
   " If subsidence either after  agitation  or after precipita-
tion be continued too long, the organisms first carried down
may again become redistributed throughout the water."
  It is essential,  therefore,  that  the liquid be filtered as
short a time after the precipitation as possible.
  Precipitation by Aluminum Compounds.—A small quantity
of  aluminum  sulfate added to natural  waters is decom-
posed with  the formation  of  a flocculent  precipitate of
aluminum hydroxid, which settles comparatively rapidly,
and carries  down with it  all suspended matters,  as  well 
           PURIFICATION OF  DRINKING  WATER.        I 27

as a large proportion  of  the  dissolved organic matters.
Waters which contain such an excess of organic matter as
to be distinctly colored may usually be made  quite clear
and  colorless by this treatment.   One grain to the gallon
will  often  suffice for the purpose, but  if very rapid sub-
sidence is desired, more may be added.
  This precipitation is  a gradual process, and a water that
will give the  test for aluminum immediately after filtering
may give none after twenty-four hours.  It is not  infre-
quently noted that such effluents, originally clear, become
cloudy on  standing, in  consequence of the  separation of
aluminum hydroxid.   On  the  addition of aluminum  sul-
fate  to brown surface waters there  is also  a precipitation
by the organic matters.   A sample of the Cochituate River
water (Boston supply), of moderately deep color, to which
25 milligrams of alum  to  the liter had been added, when
filtered gave  no  reaction, even when 2.5 liters were con-
centrated for the test.   An addition of 30 milligrams to
the liter  could be detected without difficulty.
  Several systems of filtration now  in extended use employ
this  precipitation method in conjunction with  filters of
smali area, the necessary flow being obtained by increased
pressure.   The differences between  the various forms are
chiefly in the mechanical arrangements for  supplying  the
water and for cleaning the filter.  The material is generally
sand or coke ; the cleaning is performed at short intervals,
by  means of reverse  currents of water.  The  aluminum
solution  is introduced  as needed by automatic apparatus.
  These  filters are efficient, and are suitable for the  purifi-
cation of water for manufacturing establishments, and when
large basins are not available.   It  must be  noted, how- 
128          INTERPRETATION OF  RESULTS.
 ever, that the use of aluminum sulfate will  increase the
 liability of the water to form hard scale.

   The addition of an iron salt to water containing carbon-
 ates is attended with decomposition and  the  formation of
 a precipitate of ferric hydroxid.   This reaction has been
 employed as a means of purification.   One of these meth-
 ods was by passing  the water through spongy iron, then
 aerating to precipitate the iron, and filtering through sand.
 The method  is very efficient,  but the spongy iron gradu-
 ally chokes by oxidation and becomes useless.   This diffi-
 culty is removed by the use of iron borings or  punchings
 contained in an iron cylinder,  which is rotated while the
 water passes through; the iron is brought  into  thorough
 contact with  the  water, and there is sufficient abrasion to
 keep its surface clean.
   In the  laboratory  of  the   State Board of  Health of
 Massachusetts, Drown investigated the  effect of various
 methods of aeration, such as exposing water in  bottles to
 the air of the room,  drawing a current of air through by
 means of an aspirator, shaking it in a bottle by machinery,
 and exposing  it  to air under pressure of from  sixty to
 seventy-five pounds.   While no appreciable benefit so far as
 regards the organic matter and  its decomposition-products
 occurs,  aeration appears to prevent the growth of algas,
 with the troublesome accompaniments  of bad tastes and
 odors.   It may also have a beneficial effect upon ground
 waters containing considerable amounts of iron.  These
 waters are often clear when first drawn, but become turbid
and  yellow in a  few hours  by the  separation  of  ferric
hydroxid by oxidation.   Waters from considerable depth 
           PURIFICATION  OF DRINKING WATER.        129

 often contain so little free oxygen that this oxidation does
 not occur until they reach the surface.   By applying an
 aeration method the change may be hastened, and by some
 simple  process  of  rapid  filtration  afterward applied, the
 water will be made clear  and remain so.

   Purification  of  Boiler "Waters.—The  problems
 present in the treatment  of boiler waters are  usually the
 removal of the calcium carbonate and sulfate, and magne-
 sium carbonate and chlorid.  Both carbonates are appreci-
 ably soluble in  pure water.  About one grain  of calcium
 carbonate to the gallon is usually stated to be  the propor-
tion dissolved,  but it has been  pointed out by Allen that
 solutions can be obtained  containing twice this amount.
 If the water contains carbonic acid, it will take up a much
 greater proportion  of the carbonates, but in  this case they
 will be deposited from the solution by boiling.   This has
 been accounted for by supposing the  existence  of soluble
 bicarbonates,  which  are decomposed  by  the  boiling.
 Nearly all of these carbonates  can be thrown  out of solu-
 tion by any means that will deprive  the water of the car-
 bonic acid.   Sodium hydroxid is often  employed for the
 purpose,  and should  be added in quantity just sufficient to
 form normal  sodium carbonate.  If there are  present in
 the water calcium and  magnesium  chlorids and sulfates,
 these also will be decomposed and  precipitated by the
 sodium  carbonate  so formed.  If the amount of sodium
 carbonate formed is not sufficient to decompose all of these
 bodies,  a sufficient  quantity should be  added with the
. sodium  hydroxid  to  effect  the complete decomposition.
 The precipitate is allowed to settle or filtered off.
        1 
i3o
INTERPRETATION OF  RESULTS.
  In cases in which the feed-water is heated before it enters
the boiler, it may only be  necessary to add to the water
sodium carbonate in quantity sufficient to  decompose the
calcium and magnesium chlorids  and sulfates, since the
heat alone will suffice to throw down the carbonates.
  Care should be  taken  in  these  precipitations that  no
more sodium hydroxid is added  than  is required for the
precipitation, since any excess would tend to corrode the
boiler.
   Clark'sprocess consists in treating the water with calcium
hydroxid  (lime-water).  This precipitates the calcium and
magnesium  carbonates by  depriving  the  water of  its free
carbonic acid.   It has, of  course, no effect upon the cal-
cium sulfate.   It  is to be noted that the proportion  of
calcium hydroxid which is to be added must be calculated
from the amount of free carbonic acid existing in the water,
and not from  the amount of carbonates  to be removed.
The precipitate will usually require at least twelve hours
for complete subsidence, but after three or four hours the
water will be sufficiently clear for some purposes.  If a
filter press is used, as in Porter's process, the time required
for clarification is very much  shortened.  Another advan-
tage of this process is the use of a solution of silver nitrate,
in order to determine more  conveniently the proportion
of calcium hydroxid which is to  be employed.  The lime
is first  slaked and dissolved  in water, and  the water to  be
softened run in and thoroughly mixed with it.  From time
to time small portions are taken out and a few drops of a
solution of silver nitrate added.   As long  as the lime is in
excess, a brownish coloration is produced.    When this has
become quite faint, and just about to disappear, the addi- 
           PURIFICATION OF DRINKING  WATER.       131

tion of the water is discontinued, and,  after a short time,
the water is filtered by means of  the press.

  Soluble phosphates added to a water precipitate com-
pletely in a flocculent condition any calcium, magnesium,
iron, or aluminum.  This reaction can  be best applied by
using the trisodium phosphate (Na3P04-f- i2H20), which
is now a commercial article.  By reason of the facility with
which this substance loses a portion of its sodium to acids,
it acts not only as a precipitant to the above materials, but
will neutralize any free  mineral acid present in the water.
From evidence submitted by those who have used the pro-
cess on the large scale,  it appears that not only is no. hard
scale formed, but  that scale already existing prior  to its
use is gradually disintegrated and removed with the sludge.
Experiments indicate that no injury results from  an excess
of the material; but the economical employment of the
method,  especially with very  hard waters, can only be
based  upon a correct  analysis,  and an estimation of the
phosphate required for  the  precipitation.   In many cases
the composition of the  water  will  be such that  a partial
precipitation will be sufficient.
  Considerable  success  has been obtained by the  use  of
fluorids as precipitants of scale-forming elements.   Sodium
aluminate has also been recommended.
  Waters rich  in  ferrous compounds may be purified by
thorough aeration  and filtration,  the iron being separated
as ferric  hydroxid. 
132
INTERPRETATION OF  RESULTS.
    IDENTIFICATION OF THE SOURCE OF WATER.
  The determination of the course of underground streams,
and of communications between collections of water, is
often  an important practical problem.   In geologic and
sanitary surveys, valuable information may occasionally be
gained.   The method generally pursued when  connection
between water at accessible points is to be  detected, is to
introduce at one point some substance not naturally exist-
ing in the water,  and  capable of recognition in  small
amount.   Lithium compounds are among the best for this
purpose.   They are not frequent ingredients  of natural
waters,  and  are easily  recognized  by  the  spectroscope.
Lithium chlorid is the most suitable.  The quantity  to be
employed will vary with circumstances.   It scarcely needs
to be  stated that the waters under examination should be
carefully tested for lithium before using the method.
  When the lithium method is inadmissible, recourse must
be had to other substances  of distinct  character,  such as
strontium chlorid, but this possesses the disadvantage that
a considerable  amount  may be rendered  insoluble, and
thus lost in the  ordinary transit  through soil.   Recently,
use has been made of organic coloring matters of high tinc-
torial power, one of the most suitable of which is fluores-
cein, C20H12O_,  a derivative  of  benzene.   This will  com-
municate a characteristic and intense fluorescence to  many
thousand times  its weight of water.   An entire river may
be colored by a few kilograms.   By its use an underground
communication  was demonstrated  to exist between  the
Danube and  the Ach, a small river which flows  into  the
Lake  of Constance.  The coloration is distinct  only in 
       IDENTIFICATION OF THE SOURCE  OF WATER.    133

alkaline liquids.  Other colors, such as  anilin-red, may be
employed.
  I am indebted to Dr. F. P.Vandenburgh, who conducted
the investigation, for a description  of an instance  of  the
application of the above methods.  In a suit at law grow-
ing out of  use  of a creek  for  the supply  of Syracuse,
N. Y., it  was alleged that  the creek  supplied a  spring
which  was used by a manufacturing establishment.   Tests
of the water of creek and spring for lithium were made,
ten  gallons  of each being  evaporated,  with  negative
results.  Twenty-five pounds of lithium carbonate were
converted into chlorid and poured into the  stream about
half a  mile from the spring.   Samples of ten gallons each
were taken out of the spring by almost continual dipping
during forty-eight  hours  following.   Twenty  of these
samples were examined and lithium found in each.
   Ten pounds of fluorescein were introduced at a point
about  one  mile above the spring, and the  characteristic
fluorescence  appeared at the spring about six hours after
its  introduction into the  creek.   The  greatest  intensity
of color was between six and ten hours after its introduc-
tion.
   A more important feature of the problem from a sanitary
point  of view  is  the determination of  the source  of a
given current or collection of water, when such source is
inaccessible.  Problems of this  character  are not infre-
quent  in large cities in which the systems of water-supply
and drainage  are  defective, thus  giving occasion  to
accumulations of  water  in  cellars and  similar   places.
Often, in these cases,  no extended  explorations can be
made, by reason of the adjacent buildings and conflicting 
134          INTERPRETATION  OF RESULTS.
property interests, and the question may arise whether the
water proceeds  from a leaky  hydrant,  drain,  sewer,  or
subsoil current.   It is obvious  that in  the case of the col-
lection of water in a cellar from causes other than surface
washings or entrance of rain, it must have passed through
some distance of soil, and in built-up  districts will almost
certainly be charged  with organic refuse.   To  correctly
interpret the  results, it will be necessary  to  know the
general character of the subsoil water of the district and
the  composition of the public supply.  As a  rule, the
transmission of  water through  moderate distances of soil
will  not materially  increase  the  mineral constituents.
Hence, if the sample contains an excess of dissolved mat-
ters as compared with the water-supply of  the  district,  it
may reasonably be inferred that it is derived from a drain,
sewer, or subsoil current.   In these investigations it will
generally be sufficient to  determine the total solids, odor
on heating,  chlorin,  nitrates, and nitrites.
  Occasionally,  the analytic results  will be ambiguous, and
it is  advisable to  make examinations of more than one
sample, since accidental circumstances, rain-fall, etc., may
affect the composition of  the water.
  Instances of the contamination of water by unusual sub-
stances are occasionally noted,  and these sometimes afford
a clue to the source  of  the water.  Among the instances
of this kind within my own experience may  be  noted the
contamination with   petroleum and  with soap.   In the
former case  it was evident that  the contamination was from
a leaky pipe connecting two refineries.   In the  latter  it
was shown to be derived from an adjoining building used
as a  laundry. 
ANALYTIC DATA.
ATOMIC WEIGHTS.								
Aluminum, . . .			Al	27.1	Molybdenum, . .		Mo	96
Antimony,			Sb	120	Neodymium,		Nd	144
Argon, . . .			A	40	Nickel.....		Ni	58-7
Arsenic, .			As	75	Nitrogen, . .		N	H
Barium,			Ba	137-4	Osmium, . .		Os	191
Bismuth, .			Bi	208.5	Oxygen, . .		O	16
Boron, . .			B	11	Palladium, .		Pd	106
Bromin,			Br	80	Phosphorus, .		P	31
Cadmium,			Cd	112	Platinum, . .		Pt	194.8
Calcium, .			Ca	40	Potassium, .		K	39-i
Carbon,			C	12	Praseodymium,		Pr	140
Cerium,			Ce	140	Rhodium,		Rh	i°3
Cesium,			Cs	133	Rubidium, . .		Rb	85-4
Chlorin, .			CI	35-45	Ruthenium, .		Ru	104
Chromium,			Cr	52.1	Samarium, .		Sm	lS<>
Cobalt, . .			Co	59	Scandium, .		Sc	44.1
Columbium,			Cb	94	Selenium,		Se	79.1
Copper,			Cu	63.6	Silicon, . .		Si	28.4
Erbium, .			E	166	Silver, . . .		Ag	107.93
Fluorin,			F	19	Sodium, . .		Na	23-05
Gadolinum,			Gd	156	Strontium, .		Sr	87.6
Gallium, .			Ga	70	Sulfur, . . .		S	32.06
Germanium,			Ge	72	Tantalum,		Ta	183
Glucinum,			Be	9-i	Tellurium, .		Te	127
Gold, . .			Au	197.2	Terbium, . .		Tb	160
Helium, .			He	4	Thallium,		Tl	204.1
Hydrogen,			H	1	Thorium, . .		Th	232
Indium, .			In	114	Thulium, . .		Tu	170
Iodin, . .			I	126.9	Tin, ....		Sn	118.5
Iridium, .			Ir	193	Titanium,		Ti	48.1
Iron, . .			Fe	56	Tungsten,		W	184
Lanthanum,			La	138	Uranium, . .		U	239-5
Lead, . .			Pb	206.9	Vanadium, .		V	51.2
Lithium, .			Li	7	Ytterbium, .		Yb	173
Magnesium,			Mg	24-3	Yttrium, . .		Y	89
Manganese,			Mn	55	Zinc, . . .		Zn	65-4
Mercury, .			Hg	200.3	Zirconium, .		Zr	90.6
135 
136             FACTORS  FOR  CALCULATION.
Parts
per
    FACTORS  FOR CALCULATION.
100,000   X °-7     = Grains per Imperial Gallon.
         1,000,000   X °-°7     =   "    "     "
           100,000   X °-583    =   "    "  U.  S.     "
         1,000,000   x 0.058    =   "    "     "      "
         1,000,000   X 0-°°833 = Pounds per 1000 U.  S. Gal.
         Imp. gallon  -4- 0.7      = Parts per   100,000
          "     "    -h 0.07     =   "   "   1,000,000
         U. S.   "    ~- 0.583    =   "   "    100,000
          "     "    -=- 0.058    =   "   "   1,000,000

  Parts per 100,000 divided by 2 and quotient increased one-tenth gives
approximately grains per U. S. Gallon.
        A1203,.........X 0.530   = Al
        AgCl,.........X 0.248   = CI
        BaS04,   ........X 0.589   = Ba
        BaS04,........X 0-411   = S04
        B203..........X 0.313   = B
        CaO,.........X 0.714   = Ca
        CaO,......... X 1-78     = CaC03
        CaC03.........X °-4°     = Ca
        CI...........X 1-65     = NaCl t
        Fe203,.........X °-7      = Fe
        KC1,.........X 0.524   = K
        2KCI, PtCl4.......X 0.16     = K
        2KCI, PtCl4,......X 0.30     = KC1
        Mg2P207,.......X 0.218   = Mg
        Mg2P207,.......X 0.853   = P04
        Mg2P207,.......X 0.757   = MgC03
        MnS,.........X 0.632   =  Mn
        NaCl,........X 0.393   = Na
        N,.........X 4-42     = N03
        N,..........X 3-27     =  N02
        N».........-X 5-84     = Ca(N03)2
        N...........X 121     =  NH3
        NH3,.........X 0.823   =  N 
CONVERSION  TABLE.
J37
CONVERSION  TABLE.
Parts	Grains per	Grains
per Million.	U. S. Gallon.	per Imp. Gal.
I	O.058	O.07
2	0.116	O.14
3	O.174	0.21
4	O.232	0.28
5	O.290	0-35
6	0.348	0.42
7	O.406	0.49
8	0.464	O.56
9	0.522	0.63
IO	0.580	O.70
n	O.638	0.77
u	O.696	O.84
13	0-754	O.91
14	0.812	0.98
LS	0.870	O.05
16	0.928	I.12
17	0.986	1.19
18	I.044	I.26
'9	1.102	1-33
20	1.160	1.40
21	1.218	i-47
22	I.276	i-54
23	1-334	1.61
24	1.392	1.68
25	1-45°	i-75
 Parts
  per
Million.
26

27
28
 Grains per
U. S. Gallon.
I.508
I.566
1.624
29	1.682
30	1.740
31	1.798
32	1.856
33	1.914
34	1.972
35	2.030
36	2.088
37	2.146
38	2.204
39	2.262
40	2.320
41	2.378
42	2.436
43	2.494
44	2-552
45	2.610
46	2.668
47	2.726
48	2.784
49	2.842
5°	2.900
 
138    ANALYSES  OF RAIN  AND  SUBSOIL WATERS.
ANALYSES OF RAIN AND  SUBSOIL WATERS.
Milligrams per Liter.
	From	c/5 Q J O J < h 0 H	z 2 0 j X u	d 1 > n Z	Z <	O Z < z	d z < z
Rain water. Subsoil water	Bellefonte — collected by Prof. Wm. Frear, after long rain. Wynnewood—pool fed by underground spring. Wynnewood —well about 150 yards from above. Wynnewoo d—well polluted by farm-yard drainage; about 500 yards from pool. Pump-well in densely populated district. Highly contaminated Newly dug well in populated district. Highly contaminated. Well at Barren Hill, 130 feet deep.	5 65 60 1120 620 470	none 6.20 4.00 16.00 57.00 120.00 120.00	0.148 0.032 0.024 0.208 1.00 0.08 undt.	0.280 0.024 0.016 0.028 3.120 2.00 undt.	none none none none 0.01 0.03 traces	none 2-3 3-5 14.2 33-0 16.0 22.0
 
ANALYSES  OF ARTESIAN  WATERS.          139
ANALYSES OF ARTESIAN WATERS.

           Milligrams per Liter.
Condition, . .  .

Reaction,  . .  .
SiOo.......
SO.J......
P04.......
COa (combined),
CI........
HoS.....
Mil.......
Fe.......
Ca.......
Mg,  ......
Na.......
K........
N by KM11O4,
NasNH4> . .  .
N as NO., . .  .
N as NO3, . .  .
	Philadelphia.		
CU > <	in	CA	73 a
■a -c 5	■gss		rt
M 2		"Si	C/l
5*2		O en u cu PO.S	u
		U	M
Clear.	Slightly turbid.	Clear.	Clear.
Alkaline.	Alkaline.	Alkaline.	Alkaline.
34-5°	35-oo	29.00	19.50
36-26	9.90	15.24	102.36
0.31	0.31	Trace.	0.38
110.17	54.80	108.64	50.64
91.77	108.50	172.00	554-48
Trace.		4-32	
7.70	5-7°		1.05
44.28	50.00	101.42	53-57
7.98	12.60	22.27	6.48
84.13	32.46	55-83	378.63
8-54	4.10	6.28	I race.
Not det.	0.048	0.015	0.148
Not det.	0.034	0.004	0.132
None.	None.	Trace.	None.
Trace.	None.	1.00	None.
 
EXAMPLES  OF  CITY SUPPLIES.
Milligrams per Liter.
City......	New York City.	Brooklyn.	Boston.		Cincin-nati.	Chicago.	Little Rock,Ark.	Philadel-phia.	Washing-ton, D. C.
Class of Water,	Surface.	Subsoil.	Surface.		Surface.	Surface.	Surface.	Surface.	Surface.
Total Solids, .	75-o	64.0	47.6	156.0	140.00	136.0	283.0	120.00	126.00
Chlorin, . . .	2.8	13-5	5-1	34-8	14.00	2.3	8.2	4.00	2.8
Nitrogen as Ni-trates, . . .	0.28	16.0	0.07	°-5	0.26	Trace.	1.1	1.00	1.0
Nitrogen as Ni-trites, ....	None	None.	0.001	0.01		None.		None.	0.001
Nitrogen as Ammonium,	0.009	0.001	0.008	0.38	0.003	0.005	0.012	0.01	0.00
Nitrogen by permanganate,	0.06	0.07	0.16	0.23	0.09	0.075	0.13	0.10	0.12
  The figures are taken from official reports and do not represent averages of large numbers of analyses, but
individual analyses of  samples  representative of the supplies.   The  figures  for Boston water  represent the
Cochituate and Mystic  Rivers respectively.  The  Little  Rock supply  is in the unfiltered condition ; much of
the solid matter is  in suspension. 
ADDENDUM
    TO PAGE 69
  Dibden prepares a  filtering apparatus, which  he desig-
nates a "micro-filter," in the following manner for the
collection of minute suspended matters :  A piece of com-
bustion-tubing 20  to  25 centimeters long  is cleaned and
drawn out in the middle to a capillary tube, and broken by a
file scratch at a point  at which the caliber is not  more than
two millimeters.   Each of these pieces serves for a filter.
A mixture of equal parts of air-dried  clay and  infusorial
earth is made into a  smooth,  stiff paste with water and
spread out on a slab in a layer about two millimeters deep.
One of the tubes is then held upright and the capillary end
pressed down into the mass and worked around  in circles,
by which a plug will be formed.   This  is  promptly warmed
until dry,  and then heated to redness, forming a close filter.
  The water to be examined  is filtered in considerable
amount,—one liter, for example,  if there is but  little sus-
pended matter,—first through a hardened  paper filter placed
in a funnel, precautions being taken to exclude dust.  The
deposit is  washed from  the filter paper into the  micro-
filter by means  of a jet of pure water.  The whole of sus-
pended matter collects on the top of the clay plug.  Dib-
                          141 
142
ADDENDUM.
den measures this by noting its height.   If the clay plug is
blocked by the matters which pass into it, the application
of a filter-pump may be  needed.   When the  column of
water in the small tube  is only about a centimeter in
height, the main body of the tube is cut away by means of
a file scratch and the deposit  loosened from the filter plug,
if necessary, by the use of a  platinum  wire.   The tube is
inverted so as  to bring the deposit  to  the open end, and
then cut off close to the  plug.   By this means  the  sus-
pended matter is collected in a short capillary tube open
at both ends, and  may be-by shaking brought upon the
slide, covered with cover-glass, and examined with  the mi-
croscope. 
INDEX.
 A CIDS, action on lead, 117
*"*■  Actinic method for organic mat-
       ter, 55
Action of water on lead, 117
Aeration of water, no, 128
Agar, 66
Albuminoid ammonia, 33, 105
Alkali  carbonates, determination of,
  90
Alkaline permanganate, 37
Allen, action of water on lead, 118
-----, on boiler waters, 120
-----test for zinc, 60
Alum, action of, 126
-----, test for, 62
-----, use  of, 127
Aluminum, determination of, 62, 81
-----, test for, 62
Ammonia, albuminoid, 39, 105
-----, free, 38
------free water, 37
-----from rain water, 105
-----process, 33
Ammonium chlorid, standard, 37
-----molybdate, 56
Analysis, statement of, 99
Analytic operations, 23
Arsenic, detection of, 59
Artesian water, 16, 21
-----waters, composition of, 139
Atomic weights, 135
DACHMAN'S method, 41
J->  Bacillus typhosus, culture of, 80
Bacteriologic examination, 70
Barium, detection and estimation of,
  58
Bicarbonates in water, 129
Biologic examinations, 64
Blarez' oxygen process, 57
Boiler mud, 121
-----water, 118
----------, purification of, 129
Boiler  water, statement of  results
  from, 122
Boric acid estimation, 94
*ALCIUM bicarbonate, 129
'----- carbonate, action in boiler
            waters, 129
           solubility of, 129
- compounds, removal of, 129
-, determination of, 82
- hydroxid for purifying water,
   129
- sulfate in boiler water, 121
        insolubility of, 121
Carbonates, action on lead, 118
-----, determination of normal, 89
Carbonic acid, action of, 21
-----------,free, determination of, 93
Cellar waters, examination of, 133
Chlorin, determination of, 32
-----, significance of, 103
Chromium, detection of, 58
City supplies, 140
Clarifying water, 25, 123
Clark's process  for purifying water,
  130
Collection of samples, 23
Color comparator, 43
-----, determination of, 25
-----, significance of, 100
Comparison cylinders, 43
Conversion of ratios, 136
Copper, detection of, 63
-----sulfate, standard, 64
-----zinc couple, 48
Corrosion of boilers, 119
Cribb's condenser, 36
Cultivation of microbes, 70
Culture-media, 70
    DEEP water, 21, 139
      Demijohn for water samples, 23
Denitrification, 21
x43 
144
INDEX.
Dibden's filter, 141
Distilled water, wholesomeness of,
  102
Driffield, boiler mud, 121, 122
Drown, aeration, 128
-----  and Hazen,  ignition of resi-
       due, 31
-----and Martin, nitrogen determi-
       nation, 43
Dupre, dissolved oxygen, 109


   FERRIC sulfate, standard, 60
     Ferrous   ammonium  sulfate,
      standard, 57
Filters, 125
—----, sand, 126
Filtration, 124
Fluorescein, use of, 132
Fratikland, isolation of microbes, 78
-----, nitrifying bacillus, 20
-----, purification by  precipitation,
         126
Fuller, G. W., culture-media, 72
   GALLON, Imperial, 98
   -----, U.S., 98
Gelatin culture-media, 70
    HARD scale, 121
    -----water, softening of, 130
Hardness, determination of, 89
-----, permanent, 89
-----, temporary, 89
Hehner's method for hardness, 89
Hydrogen sulfid, titration of, 87
    MAGNESIA in boiler sludge, 121
      Magnesium, determination  of,
       82
-----chlorid, effects of, 120
-----compounds, removal of, 131
Manganese, detection of, 61
-----, determination of, 83
Micro-filter, 141
1\J ESSLER reagent, 35
*•'  Nesslerizing, 37
Nitrates, action in boilers, 120
-----, determination of, 46
-----, formation  of, 20
-----, significance of, 108
Nitrification, 20
Nitrites, determination of, 44
-----, formation of, 20
-----, significance of, 107
Nitrogen in  ammonium compounds,
        33. 104J
-----as nitrates, 44
-----as nitrites, 49
-----by permanganate, 105
-----, oxidation of, 20
-----, total organic, 43
o
DOR, determination of, 28, 102
        from residue, 31
-, significance of, 100
Oxygen consumed, 51
------consuming power, 51
-----. dissolved, determination of, 57
-----------, effects of, 109
IDENTIFICATION  of source  of
■*■  water, 132
Imperial gallon, 98
Indol reaction, 77
Interpretation of results, 98
Iodin, centinormal, 87
Iron, action of, in purification, 128
-----, determination of, 60, 81
-----, significance of,  102
X^JELDAHL method, 43
EAD, action of water on, 116
     -, determination of, 62
nitrate, standard, 63
Lime, purification of water by, 124,
  130
Lithium compounds, use of, 132
-----, detection of, 95
-----, separation of, 86
   PARIETTI'S solution, 79
    Pasteur-Chamberlain filter, 125
Permanganate method, 33
-----standard, 52, 54
Petri dish, 76
Phenol broth, 79
-----disulfonic acid, 46
Phosphates, action on lead, 118
-----, determination of, 56
-----, significance of, 104
-----, use of, in purifying water, 131
Platinum, preservation of, 30
Potassium chromate  solution, 32
-----, determination of, 85
-----iodid solution, 53
-----nitrate, standard, 46
-----permanganate, alkaline, 37
Potato culture, 72
Preliminary examination, 23
Pure water, corrosive action of, 119
Purification of boiler water, 129
-----of drinking waters, 123 
INDEX.
M5
DAFTER'S method, 66
*:v  Rain water, 16
Ratios, conversion of, 136, 137
Reaction, 28
Residue, charring of, 31
Results, statement of, 98
River water, 16, 17, 100, 140
CALT, action on boiler waters, 120
0  Samples, collection of, 23
Sand filters, 126
Sanitary application, 100
-----examinations, 23
Scale,  120
Schuylkill River water, 17
Sedgwick's method, 67
Sewage, action of, 21
Silica, action of,  in water, 117
-----, determination of, 81
Silicates, action on lead,  117
Silver nitrate, standard, 32
-----nitrite, preparation of, 50
-----test for organic matter, 55
Sludge, 121
Smart, C, nature of organic matter,
  95,105
Soap solution, 91
Sodium and potassium, separation of,
carbonate, solution of, 36
  ---, standard, 89
     -, use of, in boiler waters,
         130
-----, determination of, 85
-----hydroxid solution, 57
-----nitrite, standard, 50
-----thiosulfate, 53
Solids, significance of, 101
-----, total, determination of, 29
Source of water, tracing of, 132
Specific gravity, 96
Spectroscope, 95
Spectroscopic examination, 95
Spongy iron filters, 125
Starch indicator, 53
Subsoil water, 18, no, 138
Sulfates, estimation of, 83
Sulfids, formation of, 21, 101
Sulfuretted hydrogen, determination
  of, 87
Surface water, composition of, 17, 18,
  no, 140
HpASTE, significance of, ico
 A   Technic examinations, 81
Tidy  and  Frankland,  standard  of
       purity, 109
-----permanganate process, 52
TJNCONTAMINATED waters, no
^  Unit standard , 69
Urea, decomposition of, 105  .
Urine in water, 105
U. S. gallon, 98
■\7AUGHAN,  typhoid fever  germ,
 v   116
Vegetable growth in water, 66
-----matter, 31, 106
\X/ANKLYN, standards of purity,
 vv   106
Water-supply, note on, 13
Whipple, growth of microscopic or-
        ganisms, 69
-----, unit measure, 69
Williston's method, 67
VVurtz' litmus-lactose, 74
VINC, detection of, 59
J 
 
Catalogue No. 8.
August, 1899.
      CLASSIFIED  SUBJECT
             CATALOGUE
                     OF

MEDICAL BOOKS
                    AND
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SUBJECT   INDEX.
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for upon application.
SUBJECT.                  PAGE
Alimentary Canal (see Surgeiy) 19
Anatomy (see Miscellaneous).. 14
Anesthetics..........................  3
Autopsies (see Pathology)..... 16
Bacteriology (see Pathology).. 16
Bandaging (see Surgery)........ 19
Brain ..................................  4
Chemistry............................  4
Children, Diseases of............  6
Clinical Charts......................  6
Compends......................22, 23
Consumption (see Lungs)....... 11
Dentistry.............................  7
Diagnosis............................. 17
Diagrams (see Anatomy, page
  3, and Obstetrics, page 16).
Dictionaries.........................  8
Diet and Food (see Miscella-
  neous)  .............................. 14
Dissectors............................  3
Domestic Medicine............... 10
Ear....................................  8
Electricity...........................  9
Emergencies (see Surgery)..... 19
Eye.....................................  9
Fevers.,...............................  9
Gout.................................. 10
Gynecology......................... 21
Hay Fever............................ 20
Heart.................................. 10
Histology............................. 10
Hospitals (see Hygiene)........ 11
Hygiene............................... 11
Insanity  ..............................  4
Latin, Medical (see Miscella-
  neous and Pharmacy)......14,16
Lungs.................................. 12
Massage............................... 12
Materia Medica.................... 12
Medical Jurisprudence.......... 13
Microscopy  ........................ 13
Milk Analysis (see Chemistry)  4
Miscellaneous .............<........ 14
Nervous  Diseases ................ 14
SUBJECT.                 PAGE
Nose.................................... 20
Nursing............................... 15
Obstetrics............................. 16
Ophthalmology.....................  9
Osteology (see Anatomy).......  3
Pathology............................ 16
Pharmacy............................ 16
Physical Diagnosis............... 17
Physical Training (see Miscel-
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Physiology .......................... 18
Poisons (see Toxicology)....... 13
Popular Medicine.................. 10
Practice of Medicine............. 18
Prescription- Books................ 18
Railroad Injuries (see Nervous
  Diseases)........................... 14
Refraction (see Eye).............  9
Rheumatism........................ 10
Sanitary Science................... 11
Skin..................................... 19
Spectacles (see Eye)..............  g
Spine (see Nervous Diseases) 14
Stomach (see Miscellaneous)... 14
Students' Compends..........22, 23
Surgery and  Surgical  Dis-
  eases................................. 19
Syphilis............................... 21
Technological Books............  4
Temperature  Charts..............  6
Therapeutics........................ 12
Throat ................................ 20
Toxicology........................... 13
Tumors (see Surgery)........... 19
U. S.  Pharmacopoeia............. 16
Urinary Organs.................... 20
Urine................................... 20
Venereal Diseases................. 21
Veterinary Medicine.............. 21
Visiting Lists, Physicians'.
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Water Analysis  (see Chemis-
  try)...................................  S
Women, Diseases of.............. 21
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                       ANATOMY.
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WARREN.  Compend of Dental Pathology and Dental Medi-
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                                           .80; Interleaved, $1.25

WARREN.  Dental  Prosthesis and Metallurgy. 129 Ills. $1.25

WHITE.  The Mouth and Teeth.  Illustrated.              .40

  *** Special Catalogue of Dental Books free upon application. 
8                 SUBJECT CATALOGUE
                  DICTIONARIES.
 GOULD.  The  Illustrated  Dictionary  of Medicine, Biology,
  and Allied Sciences.  Being an Exhaustive Lexicon of Medicine
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  useful Tables and numerous fine Illustrations. 1633 pages.  4th Ed.
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 MAXWELL.   Terminologia  Medica  Polyglotta.    By Dr.
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  The object of this work is to assist the medical men of any nationality
 In reading medical literature  written in a language not their own.
 Each term is usually given in seven languages,  viz.: English, French,
 German, Italian, Spanish, Russian, and Latin.
 TREVES AND  LANG.  German-English Medical Dictionary.
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           EAR (see also  Throat and Nose).
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 DALBY.   Diseases and Injuries of the Ear.  4th Edition.   38
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 HOVELL.  Diseases of the Ear and Naso-Pharynx.  Includ-
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 PRITCHARD.   Diseases of  the Ear.   3d Edition,  Enlarged.
  Many Illustrations and Formulae.                           $1.50
WOAKES.  Deafness, Giddiness, and  Noises  in the Head.
  4th Edition.  Illustrated.                                   $2.00 
MEDICAL  BOOKS.
9
                    ELECTRICITY.
 BIGELOW.   Plain Talks on  Medical Electricity and Bat-
   teries.  With a Therapeutic  Index and a Glossary.  43 Illustra-
   tions.  2d Edition.                                        $1.00
 JONES. Medical Electricity. 3d Edition.  112 Illus.    In Press.
 MASON.  Electricity; Its Medical and Surgical Uses. Numer-
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                            EYE.
 A Special Circular of Books on the Eye sent free upon application.
 ARLT.  Diseases of the  Eye.  Clinical Studies on Diseases of the
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THORINGTON.  Refraction and How to Refract.  Ilkrtra'ed.
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WALKER.  Students' Aid in Ophthalmology.    Colored Plate
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10                SUBJECT CATALOGUE.
                       FEVERS.
COLLIE.  On Fevers.  Their History, Etiology, Diagnosis, Prog-
  nosis, and Treatment.  Colored Plates.                    t^oo
GOODALL AND WASHBOURN.  Fevers and Their Treat-
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DUCKWORTH. A Treatise on Gout.  With Chromo-lithographs
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GARROD.  On Rheumatism.  A Treatise  on  Rheumatism  and
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HEALTH   AND   DOMESTIC   MEDI-
      CINE (see  also Hygiene and Nursing).

BUCKLEY.  The Skin  in Health and Disease.  Illus.      .40
BURNETT.  Hearing and How to Keep It.  Illustrated.    .40
COHEN.  The Throat and Voice. Illustrated               .40
DULLES.  Emergencies.  4th Edition.  Illustrated.        $1.00
HARLAN.  Eyesight and How to Care for It.  Illustrated.  .40
HARTSHORNE.  Our Homes.   Illustrated.                .40
OSGOOD.  The Winter and its  Dangers.                  .40
PACKARD.  Sea Air and Bathing.                        .40
PARKES.  The  Elements of Health.                   $1.25
RICHARDSON.  Long Life and How to Reach It.        .40
WESTLAND. The Wife and  Mother.                 $1.50
WHITE.  The Mouth and Teeth. Illustrated.               .40
WILSON.  The Summer and its Diseases.                .40
WOOD.  Brain Work and Overwork.                    .40
STARR.  Hygiene of the Nursery.  5th Edition.          $1.00
CANFIELD.  Hygiene of the Sick-Room.               $1.25


                        HEART.
 SANSOM. Diseases of the Heart. The Diagnosis and Pathology
  of Diseases of the Heart and Thoracic Aorta. With Plates and other
  Illustrations.                                           $6.00

                    HISTOLOGY.
 STIRLING.  Outlines of Practical Histology.  368 Illustrations.
  2d Edition, Revised and Enlarged. With new Illustrations.   $2.00
 STOHR.  Histology and Microscopical Anatomy.  Translated
  and Edited by A. Schaper, m.d., Harvard Medical School.  Second
  Edition, Revised and Enlarged.  292 Illustrations.           $3-oo 
                     MEDICAL  BOOKS.                   11


HYGIENE  AND  WATER ANALYSIS.

Special Catalogue of Books on Hygiene sent free upon application.

CANFIELD.  Hygiene  of the Sick-Room.  A Book for Nurses
  and Others.  Being a Brief Consideration of Asepsis, Antisepsis, Dis-
  infection, Bacteriology, Immunity, Heating, Ventilation, etc.   $1.25
COPLIN  AND  BEVAN.   Practical  Hygiene.   A Complete
  American Text-Book.  138 Illustrations.  New Ed.    Preparing.
KENWOOD. Public Health Laboratory Work.  116 Illustra-
  tions and 3 Plates.                                       $2.00
LEFFMANN.   Examination  of Water  for  Sanitary  and
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LEFFMANN.  Analysis of Milk and  Milk Products.   Illus-
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LINCOLN.  School and Industrial Hygiene.              .40
MACDONALD.   Microscopical Examinations of Water and
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McNEILL.  The Prevention of Epidemics and the Construc-
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NOTTER AND FIRTH. The Theory and Practice of Hygiene.
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  pages.  8vo.                                            $7-oo
PARKES. Hygiene and Public Health.  By Louis C. Parkes,
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PARKES. Popular Hygiene.  The Elements of Health. A Book
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STARR. The Hygiene  of the Nursery.  Including the General
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  Management of the Ordinary Emergencies of Early Life, Massage,
  etc.  6th Edition. 25 Illustrations.                         $1.00
STEVENSON AND MURPHY.  A Treatise on Hygiene.  By
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WILSON.  Hand-Book  of Hygiene and  Sanitary  Science.
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WEYL.   Sanitary Relations of the Coal-Tar Colors. Author-
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           LUNGS  AND   PLEURiE.

HARRIS AND  BEALE. Treatment of Pulmonary Consump-
  tion.                                                   t2 -5°
KNOPF.  Pulmonary  Tuberculosis.   Its Madern  Prophylaxis
  and Treatment in Special InstHutions and at Home.  Illus.    $3 00
POWELL.   Diseases of  the Lungs and Pleurae, including
  Consumption.  Colored Plates and other Illus.   4th Ed.    $4.00
TUSSEY. High Altitudes in the Treatment of Consumption.
                                                         $1.50 
12                SUBJECT CATALOGUE.
                      MASSAGE.

 KLEEN.  Hand-Book of Massage.  Authorized  translation by
   Mussey Hartwell, m.d., ph.d.  With an Introduction by Dr. S.
   Weir  Mitchell.   Illustrated by a series of  Photographs Made
   Especially by Dr. Kleen for the American Edition.          $2-25
 MURRELL.  Massotherapeutics.  Massage as a Mode of Treat-
   ment.  6th Edition.                                   In Press.
 OSTROM.   Massage   and the  Original  Swedish  Move-
   ments.  Their Application  to Various Diseases  of  the Body.  A
   Manual for  Students, Nurses, and Physicians.  Fourth Edition, En-
   larged.  105 Illustrations, many of which are original.         $1.00
 WARD.  Notes on  Massage.  Interleaved.     Paper cover, $1.00


 MATERIA    MEDICA   AND   THERA-

                       PEUTICS.

 ALLEN, HARLAN,  HARTE,  VAN  HARLINGEN.   A
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 BIDDLE.  Materia Medica and Therapeutics. Including Dose
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                                       Cloth, $4.00; Sheep, $5.00
 BRACKEN.  Outlines of Materia Medica and Pharmacology.  $2.75
 COBLENTZ.  The Newer Remedies.  3d Edition, Enlarged ar.d
  Revised. Just Ready.                                    $1.00
 DAVIS.  Materia  Medica and Prescription Writing.    $150

 FIELD.  Evacuant  Medication.  Cathartics and Emetics.  $1.75
 GORGAS.  Dental  Medicine.  A Manual of Materia Medica  and
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GROFF. Materia Medica for Nurses.                       $1.25
 HELLER.  Essentials of Materia Medica,  Pharmacy, and
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NAPHEYS.   Modern Therapeutics,  qth Revised Edition,  En-
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  J. Smith, m.d., and J. Aubrey Davis, m.d.
  Vol. I.  General Medicine and Diseases of Children.          $4.00
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POTTER.  Hand-Book  of Materia  Medica,  Pharmacy, and
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MEDICAL  BOOKS.
13
SAYRE.   Organic Materia Medica and Pharmacognosy.  An
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  jurious to Drugs, and Pharmacal Botany.  A Glossary and 543 Illus-
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WARING.  Practical Therapeutics.  4th Edition, Revised  and
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WHITE  AND WILCOX.  Materia Medica, Pharmacy, Phar-
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MEDICAL   JURISPRUDENCE   AND

                   TOXICOLOGY.

REESE. Medical Jurisprudence and Toxicology.  A Text-Book
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  " To the student of medical jurisprudence and toxicology it is in-
valuable, as it is concise, clear, and thorough in every respect."—The
American Journal of the Medical Sciences.

MANN.  Forensic Medicine and Toxicology.   Illus.     $6.50

MURRELL.   What to  Do in  Cases of Poisoning.   8th
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TANNER.  Memoranda of Poisons.   Their Antidotes and Tests.
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                    MICROSCOPY.

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 BEALE.  How to Work with the Microscope.   A Complete
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  them colored.                                            $6-5°
CARPENTER.  The Microscope and  Its Revelations.  8th
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LEE.   The  Microtomist's Vade  Mecum.   A Hand-Book  of
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REEVES.  Medical  Microscopy, including  Chapters on Bacteri-
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WETHERED.  Medical Microscopy. A Guide to the Use of the
  Microscope in Practical Medicine.  100 Illustrations.         $2.00 
14                SUBJECT  CATALOGUE.
               MISCELLANEOUS.
BLACK.  Micro-Organisms.   The  Formation of Poisons.   A
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BRAMWELL.  Anaemia.  Just Ready.                   $2.50
BURNETT.  Foods and Dietaries.  A Manual of Clinical Diet-
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GOULD.  Borderland  Studies.   Miscellaneous  Addresses and
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GOWERS.  The Dynamics of Life.                        .75
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HAIG.  Diet and Food.  Considered  in Relation to Strength and
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HARE.   Mediastinal Disease.  Illustrated by six Plates.    $2.00
HEMMETER.  Diseases of the Stomach.  Their Special Path-
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HENRY.  A Practical Treatise on Anemia.     Half Cloth, .50
LEFFMANN.  The Coal-Tar Colors. With Special Reference to
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MARSHALL.  History of Woman's Medical College of Penn-
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TREVES. Physical Education : Its Effects, Methods, Etc. .75
LIZARS.  The Use and Abuse of Tobacco.                .40
PARRISH.  Alcoholic Inebriety.                        $1.00
ST. CLAIR.   Medical Latin.                             $1.00
SCHREINER.  Diet Lists.  Pads of 50.                    .75
TURNBULL.  Artificial Anaesthesia.  4th Edition.  Illus. $2.50

           NERVOUS  DISEASES.
BEEVOR.  Diseases of the Nervous System and their Treat-
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GOWERS.   Manual of  Diseases of the  Nervous System.  A
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GOWERS.   Syphilis and  the Nervous System.           $1.00
GOWERS.   Diagnosis  of Diseases  of the Brain.  2d Edition.
Illustrated.
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GOWERS.  Clinical Lectures.  A New Volume of Essays on the
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MEDICAL  BOOKS.                    lfi
HORSLEY.  The  Brain  and Spinal Cord.  The Structure and
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OSLER.  Cerebral Palsies of Children.  A Clinical Study.  $2.00
OSLER.  Chorea and Choreiform Affections.             $2.00
PRESTON.  Hysteria and  Certain Allied Conditions.  Their
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WATSON.  Concussions. An Experimental Study of Lesions Aris-
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WOOD.   Brain Work and Overwork.                      .40


                       NURSING.
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BROWN.  Elementary Physiology for Nurses.            .75
CANFIELD. Hygiene of the Sick-Room. A Book for Nurses and
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CULLINGWORTH.  A Manual of Nursing, Medical and Sur-
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CULLINGWORTH.  A Manual  for Monthly Nurses. 3d Ed. .40
CUFF.  Lectures to  Nurses on  Medicine.  New Ed.      $1-25
DOMVILLE.  Manual for Nurses and Others Engaged in At-
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  ery, etc.                                                   .75
FULLERTON.  Obstetric Nursing.  41  Ills. 5th Ed.     $1.00
FULLERTON.  Surgical  Nursing.   Comprising the  Regular
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GROFF.  Materia Medica for Nurses.  With Questions for Self-Ex-
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HUMPHREY.   A  Manual  for  Nurses.   Including  General
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  16th  Ed. Illustrated.                                     $1.00
SH AWE.  Notes for Visiting Nurses, and all those Interested
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  Organization and Working of Various Visiting and District Nurse So-
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STARR.  The  Hygiene of the Nursery.  Including the General
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  agement of the Ordinary Emergencies of Early Life, Massage, etc. 6th
  Edition.  25 Illustrations.                                  $1.00
TEMPERATURE  AND CLINICAL CHARTS.  See page 6.
VOSWINKEL.  Surgical Nursing.  Second Edition, Enlarged.
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WARD.   Notes on Massage.  Interleaved.       Paper cover, $1.00


                   OBSTETRICS.
BAR.   Antiseptic Midwifery. The Principles of Antiseptic Meth-
  ods Applied to  Obstetric  Practice.  Authorized  Translation  by
  Henry D Fry, m.d., with an Appendix by  the Author.       $1.00 
16                SUBJECT  CATALOGUE.
 CAZEAUX AND TARNIER.  Midwifery.  With Appendix by
   Munde.  The Theory and Practice of Obstetrics, including the Dis-
   eases ot Pregnancy  and Parturition,  Obstetrical  Operations,  etc.
   8th Edition.  Illustrated by Chromo-Lithographs, Lithographs, and
   other full-page Plates, seven  of which are beautifully colored,  and
   numerous Wood Engravings.       Cloth, $4.50 ; Full Leather, $5.50
 DAVIS.  A Manual of Obstetrics. Being a Complete Manual for
   Physicians and Students.  3d  Enlarged and Revised Edition.  With
   Colored and many other Illustrations.                   In Press.
 LANDIS.  Compend of Obstetrics. 6th Edition, Revised by Wm.
   H. Wells, Assistant Demonstrator of  Clinical Obstetrics, Jefferson
   Medical College.  With 47 Illustrations, .80;  Interleaved,  $1.25.
 SCHULTZE.  Obstetrical Diagrams.   Being a series of 20 Col-
   ored Lithograph Charts, Imperial Map Size, of Pregnancy and Mid-
   wifery,  with accompanying explanatory (German)  text  illustrated
   by Wood Cuts.  2d Revised Edition.
      Price in Sheets, $26.00 ; Mounted on Rollers, Muslin Backs, $36.00
 STRAHAN.  Extra-Uterine Pregnancy.  The  Diagnosis  and
   Treatment of Extra-Uterine Pregnancy.                        .75
 WINCKEL.  Text-Book  of Obstetrics, Including the Pathol-
   ogy and Therapeutics  of  the  Puerperal State.  Authorized
   Translation by J. Clifton Edgar, a.m.,  m.d.  With nearly 200 Illus-
   trations.                            Cloth, $5.00; Leather, $6.00
 FULLERTON.  Obstetric Nursing.   5th Ed.  Illustrated.  $1.00

                    PATHOLOGY.
 BARLOW.  General Pathology.  79s  pages.  8vo.         $5.00
 BLACKBURN.  Autopsies.  A Manual of Autopsies Designed for
   the Use ot Hospitals for the  Insane and other Public Institutions.
   Ten full-page Plates and other Illustrations.                  $1.25
 BLODGETT.  Dental  Pathology.  By Albert  N. Blodgett,
   m.d., late Professor of Pathology and Therapeutics, Boston Dental
  College.   33 Illustrations.                                  $'-25
 COPLIN. Manual of Pathology.  Including Bacteriology, Technic
  of Post-Mortems, Methods of Pathologic Research, etc.  275 Illus-
  trations, many of which are original.  3d. Edition.   Nearly Ready.
 GILLIAM. Pathology. A Hand-Book  for Students.  47 Illus.  .75
 HALL.  Compend of General Pathology and Morbid Anatomy.
  91 very fine Illustrations.   2d Edition.      .80: Interleaved, $1.25
 HEWLETT.   Manual of Bacteriology.  75 Illustrations.  $3.00
 VIRCHOW.  Post-Mortem  Examinations.  A Description and
  Explanation of the Method of  Performing Them  in the Dead House
  of the  Berlin Charity Hospital, with Special Reference to Medico-
  Leeal Practice.  3d Edition, with Additions.                   .75
 WHITACRE.  Laboratory  Text-Book  of Pathology.   With
  121 Illustrations.                                           $1.50
 WILLIAMS.   Bacteriology.  A Manual  for Students.   78  Illus-
  trations.                                                  $'-5o

                     PHARMACY.
Special Catalogue of Books on Pharmacy sent free upon application.
COBLENTZ.  The Newer Remedies.   Including their Synonyms,
  Sources, Methods of  Preparation, Tests,  Solubilities, and Doses as
  far as known.  Together with  Sections on the Organo-Therapeutic
  Agents and Indifferent Compounds of Iron.   Third Edition, very
  much Enlarged.  Just Ready.                               $1.00
COBLENTZ.   Manual of Pharmacy.  A  New and  Complete
  Text-Book by the Professor in the New York College of Pharmacy.
  2d Edition, Revised and Enlarged. 437 Illus. Cloth, $3.50; Sh., $4 50 
MEDICAL  BOOKS.
17
 BEASLEY.   Book of  3100  Prescriptions.   Collected from the
   Practice of the Most  Eminent  Physicians and Surgeons—English,
   French,  and  American.  A Compendious History of the  Materia
   Medica, Lists of the Doses of all the Officinal and Established Pre-
   parations, an Index of Diseases and their Remedies.  7th Ed.  $2.00
 BEASLEY.   Druggists' General Receipt  Book.  Comprising
   a Copious Veterinary  Formulary, Recipes in Patent and Proprietary
   Medicines, Druggists' Nostrums, etc.;  Perfumery and Cosmetics,
   Beverages, Dietetic  Articles and  Condiments, Trade Chemicals,
   Scientific Processes, and many Useful Tables.  10th Ed.      $2.00
 BEASLEY.   Pharmaceutical  Formulary.  A  Synopsis of the
   British, French, German, and United States Pharmacopoeias.  Com-
   prising Standard and  Approved  Formulas for the  Preparations and
   Compounds Employed in Medicine. 12th Edition. Just Ready. $2.00
 PROCTOR.   Practical  Pharmacy.   Lectures on Practical  Phar-
   macy.  With Wood  Engravings and  32  Lithographic  Fac-simile
   Prescriptions.  3d Edition, Revised, and with  Elaborate Tables of
   Chemical Solubilities, etc.                                  $3-oo
 ROBINSON.   Latin Grammar of Pharmacy  and  Medicine.
   3d Edition.   With elaborate Vocabularies.                   $!-75
 SAYRE.  Organic Materia Medica and Pharmacognosy.  An
   Introduction  to the Study of the Vegetable Kingdom and the  Vege-
   table and Animal Drugs.  Comprising the Botanical and Physical
   Characteristics, Source,  Constituents, and  Pharmacopeial  Prepar-
   ations.   With  Chapters on Synthetic  Organic Remedies, Insects
   Injurious to  Drugs, and Pharmacal  Botany.  A Glossary and 543
   Illustrations.  Second  Edition.                         In Press.
 SCOVILLE.  The Art  of  Compounding.  Second  Edition, Re-
   vised and Enlarged.                    Cloth, $2.50;  Sheep, $3.50
 STEWART.   Compend of  Pharmacy.   Based upon " Reming-
   ton's Text-Book of Pharmacy."   5th Edition, Revised in Accord-
   ance  with  the  U. S.  Pharmacopoeia, 1890.   Complete  Tables  of
   Metric and English Weights and Measures.  .80; Interleaved, $1.25
 UNITED STATES PHARMACOPOEIA.   1890.  7th Decennial
   Revision.  Cloth, $2.50 (postpaid, $2.77); Sheep, $3.00 (postpaid,
   $3.27); Interleaved, $4.00 (postpaid, $4.50); Printed on one side of
   page only, unbound, $3.50 (postpaid, $3.90).
   Select Tables from  the U. S. P. (1890).  Being Nine of the Most
    Important and Useful Tables, Printed on Separate Sheets.  Care-
    fully put up in patent envelope.                             .25
 POTTER.  Hand-Book of  Materia Medica, Pharmacy, and
   Therapeutics.  600 Prescriptions. 7th Ed.  Clo., $5.00; Sh., $6.00

   *♦* Special Catalogue  of Books on Pharmacy free upon application.


           PHYSICAL DIAGNOSIS.

BROWN.  Medical Diagnosis.  A  Manual of Clinical Methods.
  4th Edition.   112 Illustrations.                        Cloth, $2.25
FENWICK.   Medical Diagnosis.  8th Edition.  Rewritten and
  very much Enlarged.  135 Illustrations.                Cloth, $2.50
MEMMINGER. Diagnosis by the Urine.  2d Ed.  24 Illus.  $1 00
TYSON.   Hand-Book of Physical Diagnosis.  For Students and
  Physicians.   By the Professor of Clinical Medicine in the University
  of Pennsylvania.- Illus.  3d Ed., Improved and Enlarged.   With
  Colored and other Illustrations.                             $i-5° 
SUBJECT CATALOGUE.
                   PHYSIOLOGY.
BIRCH.   Practical  Physiology.  An Elementary  Class  Book.
  62 lllustritions  Just Ready.                              $'-7S
BRUBAKER.  Compend of  Physiology. 9th Edition, Revised
  and Enlarged.  Illustrated.  Just Ready.    .80; Interleaved, $1.25
KIRKE.  Physiology. (15th Authorized Edition. Dark-Red Cloth.)
  A Hand-Book of Physiology.  15th Edition, Revised,  Rearranged,
  and Enlarged.  By Prof. W.  D. Halliburton, of Kings College,
  London.  661 Illustrations,  some of which are printed  in colors.
  Just Ready.                          Cloth, $3.00; Leather, $3.75
LANDOIS.  A Text-Book of Human Physiology,  Including
  Histology and Microscopical Anatomy, with Special Reference to
  the  Requirements of  Practical Medicine.  5th American, translated
  from the  9th  German Edition, with Additions  by Wm. Stirling,
  m.d.,d.sc. 84s Illus., many of which are printed  in colors.  In Press.
STARLING.  Elements of Human Physiology. 100 Ills. $1.00

STIRLING.   Outlines  of Practical  Physiology.    Including
  Chemical and Experimental Physiology, with Special Reference to
  Practical  Medicine.  3d Edition. 289 Illustrations.           $2.00
TYSON.   Cell Doctrine.  Its History and Present State.   $1.50


                      PRACTICE.
BEALE.  On  Slight  Ailments; their Nature and Treatment.
  2d Edition, Enlarged and Illustrated.                       $1-25
FOWLER.   Dictionary of  Practical Medicine.   By various
  writers. An Encyclopaedia of Medicine.  Clo., $3.00; Half Mor. $4.00
HUGHES. Compend of the Practice of Medicine.  6th Edition,
  Revised and Enlarged. Just Ready.
  Part I. Continued, Eruptive, and Periodical Fevers, Diseases of the
    Stomach,  Intestines, Peritoneum,  Biliary Passages, Liver, Kid-
    neys, etc., and General Diseases, etc.
  Part II.  Diseases of the Respiratory System, Circulatory System,
    and Nervous System; Diseases of the Blood, etc.
                         Price of each part, .80; Interleaved, $1.25
  Physician's  Edition.   In one volume, including the  above  two
    parts, a Section on Skin Diseases, and an Index.  6th Revised,
    Enlarged Edition.  575 pp.        Full Morocco, Gilt Edge, $2.25
ROBERTS.   The  Theory and Practice of   Medicine.   The
  Sections  on  Treatment  are  especially exhaustive.  9th  Edition,
  with Illustrations.                     Cloth, $4.50; Leather, $5.50
TAYLOR. Practice  of Medicine.  5th Edition.     Cloth, $4.00
TYSON.   The Practice of Medicine.  By James Tyson, m.d.,
  Professor of Clinical  Medicine in the University of Pennsylvania.
  A Complete Systematic Text-book with Special  Reference to  Diag-
  nosis and Treatment.   Illustrated.  8vo.
                   Cloth, $5.50 ;  Leather, $6.50 ; Half Russia, $7.50


           PRESCRIPTION  BOOKS.
BEASLEY.   Book of 3100 Prescriptions.   Collected  from  the
  Practice  of the  Most  Eminent Physicians and  Surgeons—English,
  French,  and  American.  A Compendious  History of the  Materia,
  Medica, Lists of the Doses of all Officinal and Established Prepara-
  tions, and an Index of Diseases and their Remedies.  7th Ed.  $2.00 
MEDICAL  BOOKS.
19
BEASLEY.  Druggists'  General Receipt  Book.  Comprising
  a Copious Veterinary  Formulary, Recipes in Patent and Proprie-
  tary  Medicines,  Druggists' Nostrums, etc. ;  Perfumery and Cos-
  metics, Beverages, Dietetic Articles and Condiments, Trade Chem-
  icals,  Scientific  Processes, and an Appendix of Useful  Tables.
  ioth Edition, Revised.                                     $2.00
BEASLEY. Pocket Formulary. A Synopsis of the British, French,
  German, and United States Pharmacopoeias and the chief unofficial
  Formularies.  12th Edition. Just Ready.                   $2.00


                           SKIN.

BULKLEY.  The Skin in Health and Disease.  Illustrated.  .40
CROCKER.  Diseases of the Skin.  Their Description, Pathol-
  ogy, Diagnosis, and Treatment,  with Special Reference to the Skin
  Eruptions of Children.  92 Illus.  3d Edition.           Preparing.
IMPEY.  Leprosy. 37 Plates.  8vo.                       $3.50
SCHAMBERG.  Diseases of the  Skin.  99 Illustrations.  Being
  No. 16? Quiz-Compend? Series.      Cloth, .80; Interleaved, $1.25
VAN HARLINGEN.   On Skin Diseases.   A Practical Manual
  of Diagnosis and Treatment, with special reference to Differential
  Diagnosis.   3d Edition, Revised and  Enlarged.   With  Formulae
  and 60 Illustrations, some of which are printed in colors.    $2.75


   SURGERY  AND  SURGICAL  DIS-

     EASES (see also Urinary  Organs).

CRIPPS.  Ovariotomy and Abdominal  Surgery.  Illus.   $8.00
DEAVER.  Surgical Anatomy. A Treatise on Human Anatomy
  in its Application to Medicine  and Surgery. With about 400 very
  Handsome full-page Illustrations Engraved from Original Drawings
  made by special Artists from Dissections prepared for the purpose.
  Three Volumes.  Royal Square Octavo.  Volume I, Just Ready.
  Cloth, $21.00;  Half Morocco or Sheep, $24.00 ;  Half Russia, $27.00
DEAVER.  Appendicitis, Its Symptoms, Diagnosis, Pathol-
  ogy, Treatment, and Complications.  Elaborately Illustrated
  with Colored Plates and other Illustrations.           Cloth, $3.50
DULLES.   What  to  Do First in Accidents and Poisoning.
  5th Edition.  New  Illustrations.                            $1.00
HACKER.  Antiseptic  Treatment  of  Wounds, According to
  the Method in Use at Professor  Billroth's  Clinic, Vienna.       .50
HAMILTON.  Lectures on  Tumors, from a Clinical Stand-
  point.  Third Edition, Revised, with New Illustrations.      $1-25
HEATH.  Minor Surgery and Bandaging,  ioth Ed.,  Revised
  and Enlarged.  158 Illustrations, 62 Formulas, Diet List, etc.  $1.25
HEATH.   Injuries and Diseases of the Jaws.  4th  Edition.
  187 Illustrations.                                          $4-5°
HEATH.  Lectures on Certain Diseases of the Jaws.  64 Illus-
  trations.                                           Boards, .50
HORW1TZ. Compend of Surgery and Bandaging, including
  Minor Surgery, Amputations, F^ctures, Dislocations, Surgical Dis-
  eases, and the Latest Antiseptic Rules, etc., with Differential Diagno-
  sis and Treatment.  5th Edition, very much Enlarged and Rear-
  ranged.  167 Illustrations, 98 Formulae.  Clo., .80; Interleaved, $1.25 
20                SUBJECT CATALOGUE.
JACOBSON.  Operations of  Surgery.  Over 200 Illustrations.
                                     Cloth, $3.00 ;  Leather, $4-°°
JACOBSON.  Diseases  of the Male  Organs of  Generation.
  88 Illustrations.                                          $6.00
LANE.   Surgery of the Head  and  Neck.   110 Illustrations.
  2d Edition.  Just Ready.                                  $5.00
MACREADY.  A Treatise on Ruptures.  24  Full-page Litho-
  graphed Plates and Numerous Wood Engravings.      Cloth, $6.00
MAYLARD. Surgery of the Alimentary Canal. 134 Illus. $7.50

MOULLIN.  Text-Book of Surgery.  With Special Reference to
  Treatment.   3d American Edition.   Revised and edited by John B.
  Hamilton, m.d., ll.d.,  Professor of the Principles of Surgery and
  Clinical Surgery, Rush Medical College, Chicago.  623 Illustrations,
  over 200 of which are original, and many of which  are printed in
  colors.                    Handsome Cloth, $6.00;  Leather, $7.00
  " The aim to make this valuable treatise  practical by  giving special
attention to questions of treatment has  been admirably carried out.
Many a reader will consult the work with a feeling of satisfaction that
his wants have been understood, and that they have been intelligently
met."—The American Journal of Medical Science.
ROBERTS.   Fractures  of the Radius.  A Clinical and Patho-
  logical Study.  33 Illustrations.                             $1.00
SMITH.  Abdominal Surgery. Being a Systematic Description ot
  all the Principal Operations. 224 Illus. 6th Ed.  2 Vols. Clo., $10.00
SWAIN.  Surgical Emergencies.  Fifth Edition.    Cloth, $1.75
VOSWINKEL. Surgical Nursing.  Second Edition, Revised and
  Enlarged,   in Illustrations,  fust Ready.                   $1.00
WALSHAM.   Manual  of Practical  Surgery.   6th Ed., Re-
  vised and Enlarged.  With 410 Engravings.                  $300
WATSON.  On Amputations of  the  Extremities and Their
  Complications.  250 Illustrations.                         $5-5o

   THROAT  AND  NOSE  (see also Ear).

COHEN.  The Throat and Voice.  Illustrated.              .40
HALL.   Diseases of the Nose  and Throat.  Two  Colored
  Plates and 59 Illustrations.                                 $2.50
HOLLOPETER.  Hay  Fever.  Its Successful Treatment.  $t.co
HUTCHINSON.  The Nose and Throat.  Including the Nose,
  Naso-Pharynx, Pharynx, and Larynx.  Illustrated by Lithograph
  Plates and 40 other Illustrations.  2d Edition.            In Press.

MACKENZIE.  Pharmacopoeia of  the  London  Hospital  for
  Dis. of the Throat. 5th Ed., Revised by Dr. F. G. Harvey. $1.00
McBRIDE.  Diseases of the Throat, Nose, and Ear. A Clinical
  Manual. With colored Illus. from original drawings. 2d Ed.   $6.00

POTTER.  Speech and  its Defects.   Considered Physiologically,
  Pathologically, and Remedially.                            $1.00


  URINE  AND   URINARY  ORGANS.

ACTON. The Functions and disorders of the Reproductive
  Organs in Childhood, Youth, Adult Age, and Advanced Life,
  Considered  in  their  Physiological,  Social, and  Moral Relations.
  8th Edition.                                              $1-75 
MEDICAL BOOKS.
21
ALLEN.  Albuminous and Diabetic Urine.  Illus.       $2.25
BEALE.  One  Hundred  Urinary Deposits.  On eight sheets,
  for the Hospital, Laboratory, or Surgery.             Paper, $2.00
HOLLAND. The Urine, the Gastric Contents, the Common
  Poisons, and the Milk.  Memoranda, Chemical and Microscopi-
  cal, for Laboratory Use. Illustrated and Interleaved.  5th Ed. $1.00
[ACOBSON. Diseases of the Male Organs of Generation.  88
  Illustrations                                            $6.00
MEMMINGER.  Diagnosis by the Urine. 2d Ed. 24 Illus. $100
MORRIS.  Renal Surgery, with Special Reference to Stone in the
  Kidney and Ureter  and to  the  Surgical  Treatment of Calculous
  Anuria.  Illustrated.                                     $2.00.
MOULLIN.  Enlargement of the Prostate.  Its Treatment and
  Radical Cure.  2d Edition.  Illustrated.                In  Press.
MOULLIN.  Inflammation of the Bladder and Urinary Fever.
  Octavo. Just Ready.                                    $i-5°
THOMPSON.  Diseases of the Urinary Organs.  8th Ed. $3.00
TYSON.  Guide to Examination of the Urine.  For the Use of
  Physicians and Students. With Colored Plate and Numerous Illus-
  trations engraved on wood.  9th Edition, Revised.            $L2S
VAN NUYS.  Chemical Analysis of Healthy  and  Diseased
  Urine, Qualitative and Quantitative.  39 Illustrations.    $1.00


          VENEREAL  DISEASES.

COOPER.  Syphilis.  2d  Edition, Enlarged and Illustrated with
  20 full-page Plates.                                       $5-°°
GOWERS.  Syphilis and the Nervous System.           1.00


                  VETERINARY.

ARMATAGE.  The  Veterinarian's  Pocket Remembrancer.
  Being Concise Directions for the Treatment of Urgent or Rare Cases,
  Embracing Semeiology,  Diagnosis,  Prognosis, Surgery, Treatment,
  etc. 2d Edition.                                  Boards, $1.00
BALLOU.   Veterinary Anatomy and Physiology. 29 Graphic
  Illustrations.                            .80; Interleaved, $1.25
TUSON.  Veterinary Pharmacopoeia.  Including the  Outlines of
  Materia Medica and Therapeutics.  5th Edition.              $2.25


          WOMEN,  DISEASES  OF.

BYFORD (H. T.).   Manual of Gynecology. Second Edition,
  Revised and Enlarged by 100 pages.  With 341 Illustrations, many
  of which are from original drawings.                        $3°°
BYFORD (W. H.).  Diseases  of Women.  4th  Edition.  306
  Illustrations.                                      Cloth, $2.00
DUHRSSEN.  A Manual  of  Gynecological  Practice.  105
  Illustrations.                                            I1 -5°
LEWERS.  Diseases of Women. 146 Illus.  5th Ed.      $2.50
WELLS. Compend  of Gynecology.  Illustrated.
                                         .80; Interleaved, $1.25
FULLERTON.   Nursing in Abdominal Surgery and Diseases
  of Women  ad Edition.  70 Illustrations.                 *'-5° 
22                SUBJECT  CATALOGUE.
COMPENDS.
From The Southern Clinic
  " We know of no series of books issued by any house that so fully
meets our approval as these ?Quiz-Compends?.  They are well ar-
ranged, full, and concise, and are really the best line of text-books that
could be found for either student or practitioner."
BLAKISTON'S ?QUIZ-COMPENDS?

   The Best Series of Manuals for the Use of Students.

Price of each, Cloth, .80.     Interleaved, for taking Notes, $1.25.

    4^" These Compends are based on the most popular text-books
and the lectures of prominent professors, and are kept constantly re-
vised, so that they may thoroughly represent the present state of the
subjects upon which they treat.
    &S"- The authors have had large experience as Quiz-Masters and
attaches of colleges, and are well acquainted with the wants of students.
    #3~ They are arranged in the most approved form, thorough and
concise, containing over 6oo fine illustrations, inserted wherever they
could be used to advantage.
    •fcS" Can be used by students of any college.
    .9SS- They contain information nowhere else collected  in such a
condensed, practical shape.  Illustrated Circular free.

No. i. POTTER.   HUMAN ANATOMY.  Sixth Revised and
    Enlarged  Edition.  Including Visceral Anatomy.  Can be used
    with either Morris's or Gray's Anatomy. 117 Illustrations and 16
    Lithographic Plates of Nerves and Arteries, with  Explanatory
    Tables, etc.  By Samuel O. L. Potter, m.d., Professor of the
    Practice of Medicine, Cooper Medical College, San Francisco; late
    A. A. Surgeon, U. S. Army.
No. 2. HUGHES.  PRACTICE OF MEDICINE. Part I. Sixth
    Edition, Enlarged and Improved.   By Daniel E. Hughes, m.d.,
    Physician-in-Chief, Philadelphia  Hospital, late  Demonstrator ol
    Clinical Medicine, Jefferson Medical College, Phila.
No. 3. HUGHES.   PRACTICE  OF  MEDICINE.  Part II.
    Sixth Edition, Revised and Improved.   Same author as No. 2.
No.  4. BRUBAKER.  PHYSIOLOGY.   Ninth  Edition,  with
    new Illustrations  and a table of Physiological Constants. Enlarged
    and Revised.  By A. P. Brubaker, m.d., Professor of Physiology
    and General  Pathology in the Pennsylvania College  of Dental
    Surgery;  Adjunct Professor of  Physiology, Jefferson  Medical
    College, Philadelphia, etc.
No. 5. LANDIS.  OBSTETRICS.  Sixth Edition.  By Henry G.
    Landis, m.d.   Revised and Edited by Wm. H. Wells, m.d.,
    Instructor of Obstetrics, Jefferson  Medical  College, Philadelphia.
    Enlarged.  47 Illustrations.
No. 6. POTTER.  MATERIA  MEDICA,  THERAPEUTICS,
    AND PRESCRIPTION WRITING.  Sixth Revised Edition
    (U. S. P. 1890).   By  Samuel O. L. Potter, m.d., Professor of
    Practice, Cooper Medical College, San Francisco ; late  A. A. Sur-
    geon. U. S. Army. 
MEDICAL  BOOKS.                    23
           PQUIZ-COMPENDS ?—Continued.

 No. 7. WELLS.  GYNECOLOGY.  By Wm.  H. Wells, m.d.,
    Instructor of Obstetrics, Jefferson College, Philadelphia.  150 illus-
    trations.

 No. 8.  GOULD  AND  PYLE.   DISEASES OF  THE EYE
    AND  REFRACTION.  A New Book.  Including Treatment
    and Surgery, and  a Section on  Local Therapeutics.  By George
    M. Gould, m.d., and W. L. Pyle, m.d.  With Formulae, Glossary,
    Tables, and  m Illustrations, several of which are Colored.

 No. 9. HORWITZ.  SURGERY, Minor Surgery, and Bandag-
    ing.  Fifth Edition, Enlarged  and  Improved.   By  Orville
    Horwitz, b. s., m.d..Clinical Professor of Genito-Urinary Surgery
    and Venereal Diseases in Jefferson Medical College ; Surgeon to
    Philadelphia Hospital, etc.  With 98 Formulae and 71 Illustrations.

 No. 10. LEFFMANN.  MEDICAL  CHEMISTRY.   Fourth
    Edition.  Including  Urinalysis, Animal Chemistry, Chemistry of
    Milk, Blood, Tissues, the Secretions, etc.  By Henry Leffmann,
    m.d., Professor of Chemistry in Pennsylvania College of Dental
    Surgery and in the Woman's Medical College, Philadelphia.

 No. 11. STEWART.  PHARMACY.  Fifth Edition.  Based upon
    Prof. Remington's Text-Book of Pharmacy.  By F. E. Stewart,
    m.d., ph.g., late Quiz-Master in Pharmacy and Chemistry, Phila-
    delphia College of  Pharmacy;  Lecturer  at Jefferson Medical
    College.  Carefully revised in accordance with the new U. S. P.

 No. 12. BALLOU.  VETERINARY ANATOMY AND  PHY-
    SIOLOGY.  Illustrated.  By Wm. R. Ballou, m.d., Professor
    of Equine Anatomy at New York College of Veterinary Surgeons ;
    Physician to Bellevue Dispensary,  etc.  29 graphic Illustrations.

 No. 13. WARREN.  DENTAL  PATHOLOGY AND  DEN-
    TAL  MEDICINE.   Third  Edition, Illustrated.  Containing
    a Section on Emergencies.  By Geo. W. Warren, d.d.s., Chief
    ot Clinical Staff, Pennsylvania College of Dental Surgery.
 No. 14. HATFIELD.   DISEASES OF  CHILDREN.  Second
    Edition.  Colored Plate.   By Marcus  P.  Hatfield, Profes-
    sor of Diseases of Children, Chicago Medical College.

 No. 15. HALL.  GENERAL PATHOLOGY AND MORBID
    ANATOMY. 91 Illustrations.  By H. Newberry Hall, ph.g.,
    m.d.,  late  Professor of Pathology, Chicago Post-Graduate Medi-
    cal School.   Second Edition.

 No. 16.  DISEASES OF  THE  SKIN.  By Jay T. Schamberg,
    m.d., Instructor in Skin  Diseases,  Philadelphia  Polyclinic.  With
    99 handsome Illustrations.

 Price, each, Cloth, .80.        Interleaved, for taking Notes, $1.25.

  In preparing,  revising,  and  improving Blakiston's ? Quiz-Com-
 pends T the particular wants  of the  student have always been kept in
 mind.
  Careful attention has been  given to the construction of each sentence,
 and while the  books will be  found  to  contain  an immense amount of
 knowledge in small space, they will likewise be found easy reading;
 there is no stilted repetition of words; the style is  clear, lucid, and dis-
 tinct.  The arrangement of subjects is  systematic  and thorough ; there
It a reason  for every word.  They contain over 600 illustrations. 
        Morris'

    Anatomy
             Second Edition,
          Revised and Enlarged.
790  Illustrations, of which many
            are in Colors.
  Royal Octavo.  Cloth, $6.00 ; Sheep, $7.00 ;
            Half Russia, $8.00.
From The Medical Record, New York.
  '  The reproach that the English language can boast of no
treatise on anatomy deserving to be ranked with the masterly
works of Henle, Luschka, Hyitl, and others, is fast losing
its force.  During the past few years several works of great
merit have appeared, and among these Morris's " Anatomy "
seems destined to take first  place in disputing the palm in
anatomical fields with the German classics.  The nomencla-
ture, arrangement, and  entire general  character resemble
strongly those of the above-mentioned handbooks, while in
the beauty and profuseness  of its illustrations  it surpasses
them. .  .  .  The ever-growing popularity of the book
with teachers and students is an index of its value, and it
may safely be recommended to all interested."
*** Handsome  Descriptive  Circular, with
  Sample Pages and Colored Illustrations,
  will be sent free upon application. 
 
32SS 
 
 
 
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