MEDICAL BOOKSELLERS,
No. 1012 Walnut Street,
PHILADELPHIA.
THE LIBRARY
OF
THE UNIVERSITY
OF CALIFORNIA
PRESENTED BY
PROF. CHARLES A. KOFOID AND
MRS. PRUDENCE W. KOFOID
Entered according to the Act of Congress in the year 1898, by
LEA BROTHERS & CO.,
In the Office of the Librarian of Congress. All rights reserved.
DORNAN, PRINTER.
wir
TO THE
MEMORY OF MY FATHER,
TO WHOM I OWE SO MUCH J TO WHOM I CAN REPAY SO LITTLE,
THIS VOLUME
IS MOST AFFECTIONATELY
DEDICATED.
PREFACE.
•FoR a number of years past it has seemed to the author
that there was need for a manual or text-book which would
give a plain statement of the fundamental principles and facts
of Hygiene and Sanitation, together with such explanations
and details, based on American practice, as would serve to
make the work clear and readable.
Of all the medical sciences that is clearly the most impor-
tant which prevents disease instead of curing it, and deals with
communities as well as with individuals. The vital inter-
est and comparative simplicity of this science have already
attracted the laity in great numbers, as well as the medical
profession, and to this intelligent interest are largely due the
remarkable advances which recent years have witnessed in
methods of preserving the public health.
The desultory and often unauthoritative articles in the
daily press or monthly magazines are scarcely fit material
for satisfying this desire for knowledge, nor, on the other hand,
can we expect any extensive study of the larger volumes on
the subject. Smaller works exist, but they are either diffuse
and lacking in system, or they detail methods and devices
adopted abroad and out of harmony with conditions here. It
is important for the medical student, at least, that the in-
formation given in such a text-book as the present should be
as concise and systematic as possible, and that it should
devote special attention to those conditions with which he is
practically concerned.
For these reasons, and because I have as yet found nothing
which exactly comprises my idea, I have ventured to offer
this volume not only to my classes, but to all who are desirous
vi PREFACE.
of doing what they can to better the health of themselves and
of those about them. The volume deals with personal as
well as public health.
In the preparation of the work the principal text-books
have been fully consulted, as well as such recent magazine
and other articles of authority as were pertinent. Quota-
tions have been credited and references indicated, in order
that the reader may know where to seek for further details or
fuller information than the limitations of this work will per-
mit. Indeed, I should do wrong were I to give any one the
idea that this volume is thoroughly comprehensive, or even a
compendium of the whole scope of hygiene or intended to be
so. The science is already too great and too important to
be treated entirely in a single volume, and, as it is so inti-
mately concerned with every one's personal welfare, it is the
author's earnest hope and desire that not only his students
but others may use this as an adjunct to further and more
extensive reading, and that, inasmuch as hygiene is destined
to be even more important in the future than it is now, all
should make use of all possible sources of authoritative in-
formation.
Whatsoever may be the faults or shortcomings of the work,
the labor expended upon it will not have been altogether in
vain if it induces any one to take greater interest in the study
of all that which pertains to ' ' the preservation and promotion
of health and the prevention of disease."
The illustrations have been selected with special reference
to the text, and those of special devices or apparatus have
been chosen as trustworthy representatives of their respective
classes. For the four photo- micrographs of bacteria I am
indebted to the skill and courtesy of Dr. William Gray, of
Washington, D. G., to whom, and to all my other friends and
associates who have aided me in the preparation of the work,
I have many thanks to extend.
SENECA EGBERT.
PHILADELPHIA, MAY, 1898.
CONTENTS
CHAPTER I.
INTRODUCTION .17
CHAPTER II.
BACTERIOLOGY 32
CHAPTER III.
THE ATMOSPHERE— AIR 59
CHAPTER IV.
VENTILATION AND HEATING . . . ... 88
CHAPTER V.
WATER . 126
CHAPTER VI.
FOOD . . . 180
CHAPTER VII.
STIMULANTS AND BEVERAGES . . . .... 220
CHAPTER VIII.
PERSONAL HYGIENE 228
CHAPTER IX.
SCHOOL HYGIENE . 253
viii CONTENTS.
PAGE
CHAPTER X.
DISINFECTION AND QUARANTINE 266
CHAPTER XI.
THE REMOVAL AND DISPOSAL OF SEWAGE . . . .298
CHAPTER XII.
VITAL STATISTICS 327
CHAPTER XIII.
THE EXAMINATION OF AIR, WATER, AND FOOD . . . 339
A MANUAL OF HYGIENE AND SANITATION.
CHAPTER I.
INTRODUCTION.
HYGIENE may be defined as the art and science that
considers the preservation, promotion, and improvement of
health and the prevention of disease. It treats of the
laws of health in the broadest sense, and under the gen-
eral term may be included a number of subdivisions. For
instance, Sanitation or Sanitary Science is usually taken
to be concerned with matters pertaining to the general
public health, while Personal or Domestic Hygiene is
more closely related to the affairs of the individual or
household.
A little thought will show that under the general head
we may consider : 1 . The preservation and promotion of
health. 2. Practical disinfection and the means of avoid-
ing preventable diseases. 3. Adaptation of diet to the
prevention and cure of perversions of nutrition; and that
under one or another of these headings will fall the dis-
cussion of the air we breathe, the water we drink, the food
we eat, the soils and surroundings of our dwellings and
communities; and at the same time, the study of the means
of recognizing, avoiding, correcting, or removing all im-
purities affecting any of these. In addition, there must
2
18 A MANUAL OF HYGIENE AND SANITATION.
be the study of climate and meteorology; of clothing and
shelter; of the care of the sick, that they may not endanger
the well; the dangers of the abuse of stimulants, narcotics,
etc. ; the desirability of chaste and temperate living, exer-
cise, rest, etc.
Parkes says that, " taking the word ' hygiene' in its
largest sense, it signifies rules for the perfect culture of
mind and body. It is impossible to dissociate the two.
The body is affected by every mental or moral action; the
mind is profoundly influenced by bodily conditions. [So
is the moral conduct of individuals or communities.] For
a perfect system of hygiene we must train the body, the
intellect, and the moral faculties in a perfect and balanced
order. " Again, he says : (< Looking only to the part of
hygiene which concerns the physician, a perfect system of
rules of health would be best arranged in an orderly series
of this kind. The rules would commence with the regu-
lation of the mother's health while bearing her child, so
that the growth of the new being would be as perfect as
possible. Then, after birth, the rules (different for each
sex at certain times) would embrace three epochs: of
growth (including infancy and youth); of maturity, when
for many years the body remains apparently stationary;
of decay, when, without actual disease, though doubtless
in consequence of some chemical changes, molecular feeble-
ness commences in some part or other, forerunning general
decay and death. In these several epochs of his life the
human being would have to be considered : First, in rela-
tion to the natural conditions which "surround him, and
which are essential for life, such as the air he breathes, the
water he drinks, etc.; in fact, in relation to nature at
large. Second, in his social and corporate relations, as a
member of a community with certain customs, trades, etc. ;
INTR OD UCTION. 1 9
subjected to social and political influences, sexual relations,
etc. Third, in his capacity as an independent being, having
within himself sources of action, in thoughts, feelings,
desires, personal habits, all of which affect health, and
which require self-regulation and control. Even now,
incomplete as hygiene is, such a work would, if followed,
almost change the face of the world/'
The student will readily see that the scope of the science
is so vast that, in a limited work like the present one, it
would be impossible to go over the entire ground com-
pletely and thoroughly. The most that can be attempted
will be to discuss its fundamental laws as we now under-
stand them, especially those that are most closely con-
nected with the conscientious physician's duties and prac-
tice, and to show the reason of or the advantages resulting
from the pursuit of hygienic and sanitary methods based
on those laws and our experience. Hygiene is, however,
a science, in the study of which common sense must be
freely used, and if one but bring this to his aid and add
to it sincere attention, he will speedily find that there is
little that is difficult, beyond his grasp, or less than really
fascinating.
It always has been, as it always will be, an art to pre-
serve health and to ward off disease. Hippocrates, about
400 B. C., in his treatise on Airs, Waters, and Places,
was the first to define principles of public health or sani-
tation; he summed up the knowledge of his day concerning
hygiene under six headings, viz. : Air, Aliment, Exercise
and Rest, Sleep and Wakefulness, Repletion and Evacua-
tion, and the Passions and Affections of the Mind; and he
even pointed out that thelre must be an exact balance
between food and exercise, and that ' ( disease would result
from excess in either direction." The excellence of the
20 ^ MANUAL OF HYGIENE AND SANITATION.
Mosaic code of the Hebrews is acknowledged by all sani-
tary authorities, and its effects are seen to this day in the
comparative longevity of the race. The Greeks cultivated
to the extreme both the physical and mental faculties, and
had for their motto A sound mind in a sound body. The
Romans, in their aqueducts for conveying water to the
city and in the Cloaca Maxima, have left some wonderful
examples of sanitary engineering, which are, in certain
respects, not yet surpassed.
The development of hygiene as a science, however, has
been within comparatively recent years. Perhaps the
first great impulse among English-speaking peoples,
especially in matters pertaining to sanitation or u State
medicine," can be traced to the labors of Dr. William Farr,
and to the establishment, through his efforts, of the
British Registrar-General's office in 1838. Since then
the task of determining the principles and laws of health
has been carried on with unflagging zeal by workers
both here and abroad, and within the last dozen of years
or so the knowledge gained in the new study of the bacteria,
especially that regarding the causation and true nature of
infectious diseases, has furnished us with a wealth of facts
with and by which we may make the foundations of our
science more unchangeable and lasting.
It would be wrong, however, to give the impression that
hygiene is, as yet, an exact science. While it is rapidly
attracting popular notice and attention, and has attained
within comparatively recent years a dignity that it did not
hitherto have in this new world, it is already on a some-
what firmer basis in the old. But the brightest minds of
the day are still busy with many of its problems, and facts
and laws are being made clear that more firmly fix or
altogether change some of our beliefs and our practice.
INTRO D UCTION. 21
Especially is such new knowledge to be sought for in the
study of the prevention of disease, the domain of bacteri-
ology, parasitic diseases, and the chemistry of the animal
alkaloids and kindred compounds.
Perhaps a few statistics will help one to realize that the
study is not in vain, and that the promise of the future is
even more brilliant than the results and achievements of
the past. Three centuries ago the death-rate of London
was more than eighty per thousand ; now it is about
twenty. It is computed that in the eighteenth century —
the one preceding the introduction of vaccination — fifty
millions of people were killed in Europe by smallpox
alone; now it is practically almost an extinct disease. In
1872 Sir John Simon estimated " that the deaths which
occur in England are fully a third more numerous than
they would be if our existing knowledge of the chief
causes of disease were reasonably well applied throughout
the country, and that of deaths which in this sense may
be called preventable the average yearly number in Eng-.
land and Wales is about 120,000." In confirmation of
the accuracy of this statement, official reports show that
the average death-rate of England and Wales from 1862
to 1871 was 22.6 per 1000, and that of 1881 was 18.9,
this giving a saving of 92,000 lives annually; while for
1889 the death-rate was 17.9, indicating a yearly saving
of at least 125,000 lives, even with the correction for the
lowered birth-rate. Moreover, the death-rate from the
seven principal zymotic (infectious) diseases had dropped
from an average of 4. 11 for 1&61 to 1870 to 2.40 for 1881
to 1885, and that of typhoid fever from 0.39 per 1000 in
1869 to 0.137 in 1892. This for England and Wales. In
Munich from 1866 to 1881 the average yearly hospital
admissions of typhoid-fever cases were 594, or 3.32 per
22 A MANUAL OF HYGIENE AND SANITATION.
1000 of population, and the average deaths from this dis-
ease were 208 or 1.15 per 1000. From 1881 to*1888,
following the introduction of improved systems of sewer-
age, the average hospital admissions (typhoid) were 104,
or only 0.42 per 1000, and the average deaths were 40,
or only 0.16 per 1000 of population.
In this country a like improvement is to be noted,
though it is only within the last few decades that
much attention has been given to sanitary affairs. The
death-rate of most of our cities is being progressively
lowered, though the populations are constantly increased
by large numbers of ignorant and uncleanly immigrants
from abroad. Improved sanitary laws are being enacted
and enforced, streets better paved and cared for, houses
more properly constructed and ventilated, more attention
given to isolating the sick and protecting the well, and
the people in general are widely awakening to the impor-
tance of improving as well as maintaining the public
health. New York has reduced her death-rate within the
last decade (1887 to 1897) from 26.32 to 19.50; Chicago,
from 20.27 to 13.46; Philadelphia, from 21.85 to 18.72.1
Nevertheless, there is still much to be done. Tubercu-
losis, which causes from one-seventh to one-fourth of all
the deaths in the world, is practically a preventable dis-
ease, and we now not only know its cause, but also have
efficient means for a cure in a large proportion of cases, as
well as for its general prevention. So with a number of
the other infectious diseases. Every day marks an increase
in our knowledge of their etiology and the securing of
immunity from them, and not only must physicians make
use of this knowledge as they acquire it, and use their
1 From the Board of Health Reports of the respective cities.
INTR OD UCTION. 23
utmost endeavors to secure the enactment and enforcement
of sanitary laws and regulations, but they must realize
that a large part of their work lies in the enlightenment
and education of the people in all matters pertaining to
the public health.1
In the preparation of a study like the one on which we
are about to enter there is some question as to just what
may be the most advantageous order and arrangement of
the subjects to be treated. For instance, it would be
interesting to discuss our science in its relation, in turn,
to the individual, the household, and the people in general
— that is, personal, domestic, and public hygiene; and to
show wherein the treatment of these subdivisions is sim-
ilar and wherein they differ; and such a threefold consid-
eration would be not only logical, but extremely instructive.
However, since the bacteria have been shown to have so
important a part in many of the processes intimately con-
nected with health or disease, it will doubtless be advisable
to devote the opening chapter to a brief review of the
science of bacteriology. This done, it seems to the writer
that we shall, as beginners, obtain a more comprehensive
and thorough view of our subject if we pursue a method
somewhat as follows : First, to discuss air, water, and food
— three things absolutely essential to life — in all the vary-
ing conditions and circumstances under which they may
affect the bodily welfare, either for good or bad, of the
individual or of the community. Then, to take up in
1 It is encouraging to find that, although 10 per cent, of the whole number of
deaths recorded in Philadelphia in 1895 'were caused by consumption, a progres-
sive and marked lowering of the death-rate from this disease in that city is taking
place, and that, notwithstanding an increase in population of almost 40 per cent.,
the fatalities from this, disease are actually less in number than they were sixteen
or seventeen years ago. For example, the deaths from pulmonary tuberculosis in
1880 numbered 2692. a rate of 3.178 to the 1000 living ; while in 1897 there were
only 2388 deaths, or a rate of less than 2.1 to 1000 living.
24 A MANUAL OF HYGIENE AND SANITATION.
such order as may seem best the other themes, whose con-
sideration is only a degree less important than the above
in the preservation of health and prevention of disease;
such as climatology, habitations, disinfection and quaran-
tine, disposal of sewage, clothing, exercise, school hygiene,
etc. In this way, while the whole ground may not be
covered, the importance of the various subdivisions may
be estimated in their relationship to one another, and we
shall be the better prepared to pursue the study as oppor-
tunity may offer in the future.
It is doubtless in place just here to review briefly the
reasons why it is the special duty of the physician to be
able to recognize and remove insanitary conditions wherever
they may be found, and why he should make particular
and constant study of this science in all its branches and
developments.
Every true physician soon finds that the respect and
affection of his patients and associates are worth far more
than mere mercenary gain, and that his highest aim should
be to prevent disease rather than simply to cure it. And,
though this may seem to militate against his personal
interests, he is unworthy the name of physician if his
object and purpose is solely or primarily to make money.
However, the observer quickly learns that in a community
kept in good health and hygienic condition there will
always be more or less need of a doctor's services, in spite
of every effort to prevent sickness, and that such a com-
munity will pay more promptly and more liberally for
such services than one in which all sanitary precautions
are neglected. Health means ability to work and to earn
good wages ; and a healthy community means more busi-
ness, more money, and more comforts. Moreover, as a
rule, good wages ensure prompt and cheerful payment of
IN TROD UCTION. 25
the doctor's bills, as well as of others. We may note here
the close relations existing between sanitary science and
social and political economy — a relationship which is very
intimate, as we shall see from time to time in our work,
for as the physical condition of a people is bettered it
becomes more easy and more certain that they will like-
wise improve both mentally and morally.
Again, though the science of hygiene and sanitation is
comparatively a new one, public attention is being strongly
directed toward it, not only because it vitally interests
every one, but because new discoveries and new applica-
tions of the laws pertaining to it are being constantly
made, which are, in time, swiftly given to the world by
both the scientific and the popular press. This creates a
demand for first-class teachers, which demand is bound to
increase in the near future and promises materially to
exceed the supply. In fact, within a very few years not
only the medical, but the academic and scientific colleges
of the country will be compelled by powerful public opin-
ion to establish in their faculties well-equipped and well-
endowed chairs of hygiene and sanitary science, and it
will be from the ranks of the educated physicians of the
country that these teachers must naturally come. It will
not be long before the people in general realize that it is
as important that the college student or graduate be
instructed how to do his part in taking care of the health
of himself, his future family, and the community in which
he is to reside, as that he shall be well read in the abstract
principles of theology or the classics of dead languages.
So, also, considerably more time and attention than are
now accorded to it should be given to hygiene in the work
of the various normal schools for teachers. The gradu-
ates of these schools will have much of the physical as
26 A MANUAL OF HYGIENE AND SANITATION.
well as the mental welfare of thousands of young and
growing children in their keeping, and it is unquestionably
their duty to prevent or obviate the ills of school-life as
far as is in their power, and to give instruction in and
inculcate habits of living which will continually tend to
improve and preserve the physical health of those under
their care. One need scarcely intimate that, as the subject
and its study are comparatively new and the demand for
instructors is likely to be in excess of the supply, the
recompense of the latter should be accordingly lucrative.
Lastly, the time has come when a physician must neces-
sarily have a knowledge of hygiene, preventive medicine,
and sanitary science. Many States require as thorough
examinations in this as in any other branch of medicine,
before granting the right to practice within their bounda-
ries. So do the army, navy, and marine hospital services
of the Government. Moreover, the people generally, as
I have intimated, are awakening to an interest in sanitary
matters and the prevention of disease, and expect their
physicians to be well versed on all pertaining subjects; if
they find a doctor lacking in knowledge or interest in this
respect, they are apt to think, rightly or wrongly, that
he will also be deficient in the other branches of medicine.
Happily these causes all combine to place preventive on
the same high plane with curative medicine, and the time
is fast passing in which the chair of hygiene fails to have
a primary place in any thorough medical school.
It is evident that the successful physician and practical
student of hygiene must have a thorough knowledge of
three things : 1. Health and its laws; how to obtain and
preserve it. This, of course, implies a knowledge of the
human body and its functions, viz., of anatomy, physiol-
ogy, and physiological chemistry. 2. He must study dis-
INTR OD UCTION. 27
ease and its causes and nature. He must also understand
the distinction between diseases due to causes external
and those due to causes internal to the body; and that,
while some of these causes may be prevented or modified,
others, with our present knowledge, may not be so readily
overcome. 3. He must be conversant with and know
how to use the therapeutic agents, both preventive and
curative, that he has at his disposal, including not only
drugs, but also all substances and forces that he can make
efficacious to his purpose. The workman must know his
tools to be able to use them intelligently.
Health is " that condition of the body and its organs
necessary to the proper performance of their normal func-
tions/7 and disease may be defined as " a condition of the
body marked by inharmonious action of one or more of
the various tissues or organs, owing to abnormal con-
dition or structural change." It is, accordingly, well to
consider briefly the nature and causes of disease, that we
may the better understand the influence upon its preven-
tion or production of all those varying phases and con-
ditions of our .environment which we hope to study in
our work.
Disease is an entity, not a spiritual thing; a condition,
not a theory. Consequently, it is to be combated with
matter, force, and physical means, though not necessarily
with violence. In fact, when once we understand the
minuteness and delicate structure of the ultimate cells and
tissues affected, we realize that oftentimes the gentlest
application of the forces and means employed may be the
most helpful and efficient. But when one has seen the
ravages caused by it, as revealed in the pathological labo-
ratory and at autopsies, not to speak of its manifestations
in the living, as seen in the sick-room and in hospitals, I
28 A MANUAL OF HYGIENE AND SANITATION.
am sure that he cannot logically, or even for a moment,
give credence to those who proclaim that it can be dissi-
pated by the mere action of mind or of faith ; nor to those
others who declare that by subdividing and diluting and
subdividing again a single grain of substance, whether
primarily powerful or inert, you endow it with a miracu-
lous power to remove the "ills that flesh is heir to."
Virchow gave a priceless boon to modern medicine in his
theory of cellular pathology and in showing its superiority
to the old humoral theories and a priori reasoning. He
wrote "whatever outside of a cell acts upon it (abnormally)
works a mechanical or chemical change within it, which
change is disorder or disease."
For convenience sake, diseases may be divided into two
main classes, somewhat different in their origin, nature,
and character, although the dividing line between the
classes is not always as marked as it would appear to be
at first sight. The first class arises within the body
through some alteration or disturbance of nutrition and
assimilation, or of function, and may be called autogenetic.
The second class comprises those which, are due to causes
from without, favored, it may be, by either internal or
external predisposing conditions, but of necessity depend-
ing upon the reception or inoculation of the special cause,
which cause has the power of reproduction and develop-
ment, of vitality and virulence. Such diseases are called
contagious, infectious, specific, or zymotic.
A third class might also be indicated, which would
include those maladies which are almost purely psychical
and whose symptoms are largely notional and the result of
perverted imagination. But it is a question whether the
primary cause of such disorders is not an altered and
abnormal nutrition of the general nervous economy of the
INTR OD UCTION. 29
body, or else the reflex manifestations of irritative distur-
bances of distant organs.
In the first class, with our present knowledge, we should
place such maladies as rheumatism, gout, diabetes, neuras-
thenia, etc. ; while into the second will obviously fall all
that are now known to be due to living "germs" or
organisms, such as cholera, typhoid fever, malaria, etc.
However, we must not overlook the numerous 'impulses
often given to the causation of certain members of the
second class by faulty conditions of nutrition or assimila-
tion, as is especially exemplified in many cases of tubercu-
losis. The character of the soil may influence the growth
and product of the plant almost as much as the species
itself.
Prophylaxis is " the use of hygienic or other precautions
conducive to the prevention of disease;77 or it may be
defined as (t a series of methods or procedures whereby
disease is restricted and prevented by suppressing or
removing its predisposing conditions, and destroying or
modifying the exciting causes.77 Its first function, of sup-
pressing or removing predisposing conditions, is accom-
plished by sanitation'; the second, that of destroying or
modifying exciting causes, is carried out by disinfection.
The words "predisposing conditions77 should be used
instead of "predisposing causes,77 because these condi-
tions cannot in themselves originate a disease, though
they may make the system more susceptible to the excit-
ing causes of a disease.
As we have, as yet, very little definite knowledge of the
real nature of the exciting causes of autogenetic diseases,
they being developed and elaborated within the body, and
as disinfection, or the destruction and modification of these
exciting causes, is an essential feature of prophylaxis, we,
30 ^ MANUAL OF HYGIENE AND SANITATION.
at present, naturally look for more satisfactory results in
the application of prophylaxis to the second class of dis-
eases; but it does not prevent or restrict the employment
of certain prophylactic measures in regard to the first class,
such as the selection of proper diet, clothing, climate, etc. ,
and the removal or counteracting of all causes favoring
malnutrition. We may, therefore, say that sanitation is
the defensive, disinfection the aggressive part of prophy-
laxis.
To remove and suppress predisposing conditions and to
prepare the body to resist and repel the action of exciting
causes, we must not only strengthen its resisting powers,
but also make all external media as favorable to it and as
hostile to the exciting causes as possible.
The resisting powers of the body must lie in the indi-
vidual cells and tissues of the body, including the vital
fluids, and it is but natural to suppose that this repellent
action to noxious substances is best performed when the
cells and tissues are in most perfect health and most vig-
orous. This is not only good logic, but all our experience
and scientific research go to show that it has a firm foun-
dation in fact.
We shall soon learn that purity of the external media
and environment of the body is essential to its health and
that of its component tissues, and that conditions of
impurity in these media predispose to disease. We shall
also learn that a proper and sufficient supply of whole-
some food is essential to health, and that certain other
factors, as sex, age, clothing, climate, etc., may or may not
predispose to disease. In other words, if we strengthen
the resisting powers of the system to the fullest extent and
remove all predisposing .conditions, in all probability the
exciting causes will be inoperative, and there will be no
INTRODUCTION. 31
incurrence of disease. This is the essence of sanitation :
to secure perfect health, to increase the inherent power to
resist noxious and harmful influences, and to make all the
surroundings and environments of the body pure and free
from depressing factors. This applies equally to both classes
of disease; for with healthy cells and proper food there
will not be faulty nutrition and assimilation and the con-
sequent production of the exciting causes of autogenetic
disease; and with a vigorous resistance and pure sur-
roundings there is little opportunity for the germs of con-
tagious maladies to obtain a foothold within the system
long enough to reproduce themselves and cause their char-
acteristic diseases. The best means of preventing disease
is to learn and apply the best means of attaining and
retaining a healthy and vigorous state of the system, viz.,
to learn and observe the laws of hygiene.
CHAPTEE II.
B ACTERIOLOGY.
THE increase in the knowledge concerning the lowest
forms of life, and the discovery within recent years that
these often have a truly causative action in the excitation
of many maladies, have greatly facilitated the study of the
causes and prevention of disease. In fact, it is largely to
this advance in knowledge and to the confirmation of the
germ theory that much of the success of modern hygiene
and sanitation is due.
The unicellular, vegetal micro-organisms divide them-
selves into two general classes with respect to their manner
of reproduction, viz., those that multiply by budding — the
bladomyceteSj and those that increase by simple division or
fission — the schizomyedes. In the former class we have
the hyphomycetes or mould-fungi, and the saccharomycetes
or yeasts, examples of these being familiar to every one.
However, it is with the fission-fungi or bacteria, as they
are now more generally known, that we are most con-
cerned as sanitarians, since they practically include almost
all those vegetal micro-organisms that are more or less
closely connected with the production of disease, compara-
tively few of the yeasts and moulds being pathogenic, and
then only indirectly or in a minor degree.
Bacteriology, then, is the science of those unicellular,
vegetal micro-organisms that multiply by direct division
(fission), or, as occasionally happens, by the development
of spores. Its study consists in the examination by means
BACTERIOLOGY. 33
of the microscope of the form and method of growth
of these minute plants, in their artificial cultivation on
or in suitable media, and in the determination of the effects
of the inoculation of pure cultures upon animals. To this
may be added another field of research that gives promise
of rapid development in the near future, viz., the study
of the chemistry of the bacterial products and the reac-
tions produced by them in culture media and in living
tissues.
Although more than two centuries have elapsed since
the discovery of the bacteria by Leeuwenhoek (about
1680), and though Plenciz advanced what is practically
the germ theory of to-day as early as 1762, most of our
knowledge concerning the physiology, methods of cultiva-
tion, and differentiation of the bacteria have been acquired
within the last fifteen or twenty years. It is true that
some advance had been made in sterilization, and that
Cohn, by establishing the fact of spore-formation, demol-
ished the last arguments in favor of spontaneous genera-
tion, and confirmed the science of bacteriology; but until
the few years just preceding the last decade we had but
little knowledge as to the means of separating and isolating
the different species and making pure cultures, or of pre-
paring culture media, staining, etc.
As already intimated, the bacteria are unicellular organ-
isms, usually multiplying by a. process of cell-elongation
and fission. Being deprived of . chlorophyll, they cannot
absorb and decompose carbonic acid and ammonia, as do
the higher plants; but require-for their growth and nutri-
tion organic matter — usually soluble albumin — in the
presence of moisture. Hence they must be either sapro-
phytes or parasites. As the combination of albuminous
organic matter and water is extremely common, so the
3 .
34 A MANUAL OF HYGIENE AND SANITATION.
distribution of the bacteria over the earth is widespread
and practically universal.
Some of the bacteria may, however, under adverse con-
ditions, such as lack of nutriment or moisture, too alkaline
or acid a medium, extremes of temperature, etc., or, on the
other hand, as a result of the attainment of a stage of maxi-
mum development, produce spores which are much more
strongly resistant to deleterious influences than the bacteria
themselves. In this way the spore-forming bacilli may
FIG. 1.
Micrococci (gonococcus) in pus-cells. X 1000.
often survive the action of disinfectants or other agencies
that are sufficient to destroy other bacteria. Upon the
resumption or recurrence of favorable conditions the spores
develop into cells similar in form and nature to their parent
cells.
It is to be remembered that spores do not reproduce
spores, and that " a single cell produces but one spore."
1 Abbott : " Principles of Bacteriology," 1st ed., p. 31.
BACTERIOLOGY. 35
Under the microscope the spores are seen as highly refrac-
tive, spherical bodies that stain with difficulty, and evi-
dently have a very resistant envelope, probably of cellu-
lose. The interior of bacteria and spores is protoplasm.
So far as we positively know at this time, only certain
bacilli form spores, though there is a possibility that a
few of the spirilla and one or two species of micrococci
have the same faculty.
Again, under certain peculiar conditions some organisms
may develop another morphological change, the so-called
FIG. 2.
<*~*Y\S*k&&*i</ '-
- - • SV>-V
Tubercle bacilli in sputum, x 1000.
involution forms. These are doubtless pathologically dis-
torted cells, with probably less than normal resisting
powers, but which will again revert to the normal under
favorable conditions, providing the unfavorable environ-
ment does not first kill them.
Lastly, there are times when certain individuals of a
36 A MANUAL OF HYGIENE AND SANITATION.
species seem to have departed from the typical form, these
departures being only different phases in the normal devel-
opment. Thus a young bacillus may be shorter than the
adult and look much like a coccus, or a coccus about to
undergo division may be oval in shape and considerably
larger than the quiescent members of its species. But
one form of bacteria never permanently takes that of
another — micrococci are always inicrococci, bacilli always
bacilli, etc.
A thoroughly scientific classification of the bacteria is
scarcely possible as yet, owing to our incomplete knowledge
of their character, method of growth, physiology, etc.
However, there are a number of ways in which we may
subdivide them, none of them exactly scientific, perhaps,
but still sufficiently accurate and convenient for our pur-
pose. If we consider them as to form we have : (a)
micrococci, spherical in shape; (6) bacilli, which have one
diameter longer than another; and (c) spirilla, spirals or
segments of spirals. We shall have more to say hereafter
of the characteristics of each of these subdivisions. Accord-
ingly as they live best with or without air or oxygen they
are aerobic or anaerobic. Again, they may be named
according to their product; e. g., some produce colors,
chromogenic, others pus, pyogenic, etc. Lastly, they are
either saprophytic or parasitic. Some of the micrococci
are named according to the manner in which they grow.
If in pairs, they are called diplococci; in fours, tetracocci;
in threads, streptococci, etc. Groups or masses of micro-
cocci or bacilli held together by a gelatinous substance
are called zooglea. With one or two exceptions we know
but little about the spirilla. The germ of cholera — the
comma bacillus (?) — belongs to this class, and the cause of
relapsing fever is also probably a spirillum.
BACTERIOLOGY. 37
Most of the bacteria thrive best in culture media that
are neutral or only slightly alkaline, though a few species
seem to do better in slightly acid surroundings. So, also,
they do best at temperatures ranging between 20° and 40°
C. (68° and 104° F.), though they may grow between 5°
and 43° C. (41° and 109.4° F.). Any marked deviation
in the culture media from the neutral point or continued
exposure to extremes of temperature may either check the
Spirillum of Asiatic cholera. X 1000.
growth of the organisms altogether, and eventually destroy
them, or may cause spore formation, or the production of
involution forms, or may cause a change in the composi-
tion and the character of the chemical products which the
bacteria normally produce. This also holds good with
respect to any other condition or substance that may be
deleterious to the bacteria in their normal state; and we
shall see that this is important as having a decided influ-
38 A MANUAL OF HYGIENE AND SANITATION.
ence in lessening the virulence of pathogenic bacteria and
bringing about a condition of immunity to their attacks.
As it is rare to find isolated individual species anywhere
except in artificially prepared pure cultures, it is evident
that we must devise some way of separating the different
kinds of organisms one from another. This is best accom-
plished by the method suggested by Koch, viz., to intro-
duce the mixed kinds into some melted culture medium,
FIG. 4.
Bacilli of hog cholera showing flagellae. X 1000.
like nutrient gelatine, which solidifies on cooling, but
whose melting point is not sufficiently high to destroy the
vitality of the germs. If the fluid be then shaken, the
various species will be distributed through it, and upon
cooling each individual or group of individuals of the
same kind (zooglea) will be fixed in its place and become
the starting point of a colony of that special kind; and if
the gelatine be poured out before cooling upon sterilized
BACTERIOLOGY. 39
glass plates or into flat (Petri) dishes (Fig. 5), the subse-
quent work of counting, examining, and making cultures
from the colonies will be greatly facilitated. Moreover,
this process may be repeated until absolutely pure cultures
are obtained of each species in the original mixture.
FIG. 5.
Petri double dish, now generally used instead of plates.
Special care must be taken in this, as in all other bacte-
riological methods or operations, to prevent contamination
of our cultures, media, or apparatus by other organisms,
which are almost omnipresent, and which would prevent
any accurate results or deductions whatever, were they not
rigidly excluded or destroyed. Obviously, we may not
use the ordinary chemical disinfectants or antiseptics as
a means of destroying and removing these interfering
microbes, for by their action we should destroy or check
the growth of the bacteria we desire to cultivate ; but must
sterilize by heat all the articles we use, together with their
contents. This, if properly done, does not affect the nutri-
ent properties of the culture media, while it removes the
danger of subsequent contamination.
In sterilizing we may use either dry or moist heat, the
latter being by far more preferable in most cases (Figs.
6 and 7), since to be effectual it does not require so high
a temperature nor so long a time as does the former.
Moist heat, especially in the form of steam, is more pene-
40
MANUAL OF HYGIENE AND SANITATION.
trating than dry heat; beside, the dry heat requires to be
of so high a temperature that it may spoil for culture pur-
poses such substances as the nutrient gelatine. Glassware
and the like, however, may be quickly and advantageously
sterilized by dry heat. On the other hand, certain sub-
FIG. 6.
Steam sterilizer, pattern of Koch.
stances, like blood-serum, are ruined by moist heat con-
tinued long enough to destroy the spores possibly present,
as the latter need a much higher temperature to sterilize
them than the former. So we resort to fractional steril-
ization in such cases, exposing our materials for only a
short time to a temperature just sufficient to destroy the
bacteria, repeating the process after an interval which is
sufficient to allow the spores to develop into bacteria, say,
BACTERIOLOGY. 41
twenty-four hours, and sterilizing again a third time after
a like interval. Having thus sterilized the culture media
and apparatus, we prevent the access of contaminating
germs to the interior of our tubes and vessels by plugs of
sterilized cotton-wool, covering these, when necessary, with
rubber caps to prevent the evaporation of fluids or of
moisture from the gelatine, etc.
FIG. 7.
Arnold steam sterilizer.
As a basis for a number of culture media, we may use
beef -broth or bouillon, which is a fluid especially favorable
to bacterial growth, in that it contains an abundance of
albumin in solution. When a solid medium is desired,
either gelatine or agar-agar (a 'sort of vegetable gelatine
from Japan) may be added to this, giving us nutrient gela-
tine and nutrient agar-agar. Of these, the gelatine has a
melting-point below the temperature of the human body,
42 A MANUAL OF HYGIENE AND SANITATION.
while the agar has not, so we have to employ the latter
when it is desired to cultivate germs that grow best at the
body-temperature, although the development of most bac-
teria is usually more rapid and characteristic upon the
gelatine. Sterilized and solidified blood-serum is also used
for the cultivation of certain organisms, like the diphtheria
bacillus, and there are certain others which can only be
differentiated by their difference in growth upon boiled
potato, milk, etc.
The differentiation of the various species of bacteria is
to be made by noting their appearance and form under the
FIG. 8.
Kuled square for counting colonies.
microscope, whether they are motile or not, how they take
different stains, etc.; by observing their methods of growth
in or upon different culture media, whether they are
aerobic or anaerobic or facultative; at what temperatures
they do best, etc., and finally by studying their action and
the action of the substances they produce upon living
animals. In this way we may determine the characteris-
tics of each individual or species, and will eventually have
the groundwork and material for a strictly scientific classi-
fication of the schizomycetes. For example, the organisms
causing suppuration are micrococci, occurring in clusters
(staphylococci) or in chains (streptococci); the cause of
typhoid fever is a bacillus, and the cholera germ belongs
BACTERIOLOGY.
43
to the spirilla. The tubercle bacillus stains with marked
difficulty, but wheu stained is not readily decolorized by
a weak solution of nitric acid as are almost all other bacilli.
Some bacteria liquefy nutrient gelatine, others do not, and
almost none liquefy agar-agar. This liquefaction is not
FIG. 9.
Pocket-case containing sterilized culture tubes, platinum needle, and small
alcohol lamp used for obtaining cultures for diagnosis, etc.
a melting, but rather a probable peptonization, since the
gelatin will not solidify again after it occurs, as it will after
being subjected to moderate warming. Again, some bac-
teria produce one color or chemical substance in the pres-
ence of oxygen, and another in its absence; some only pro-
duce color in the light, others only in the dark, etc. Finally,
44 A MANUAL OF HYGIENE AND SANITATION.
as we already know, different pathogenic microbes produce
different maladies when inoculated in animals or human
beings, and the same germ may produce different results
in animals of different species or families.1
The subdivision of the bacteria into saprophytes and
parasites has been already noted, and it must be remem-
bered that not all of these microscopic plants are disease-
producers, much the larger proportion, in fact, being bene-
factors rather than otherwise to the human race.
The function of the saprophytic organisms is to break
up dead organic matter into simpler chemical compounds
and ultimately into carbonic acid, ammonia, and water;
these latter substances being once more utilized in the
nutrition of the higher forms of vegetable life, which are,
in turn, necessary to the existence of animal life upon the
globe. Indeed, it is only when the student of hygiene
fairly realizes the great scope of the functions of these
minute but almost omnipresent scavengers that he can
comprehend the important part they play in the purifica-
tion of our environment. In the air they possibly help
the oxygen to destroy the harmful effluvia and exhalations
of men and animals and the floating debris of organic
substances; in the soil, the common receptacle of the
wastes and refuse of vital activity, they quickly and con-
tinually convert these noxious additions into foods of the
highest value to growing plants; in running streams and
quiet pools they are of the greatest importance in the
removal of the dangerous impurities washed from the
surface of the land or recklessly discharged from human
habitations, factories, and the like. And not o'nly do the
saprophytes help mankind in this way, but members of
1 See Kenwood's " Hygienic Laboratory," pp. 466-70 ; also McFarland's " Path-
ogenic Bacteria," pp. 46-57.
BA CTERIOL OGY. 45
the class are beneficent in many others. For example,
they enable those plants, the leguminosae, which yield us
the largest supply of vegetable proteids, to derive much
of their nitrogen almost directly from the atmosphere;
they have much to do with the flavor and value of dairy
products, and new uses in which they may be employed
in the domestic or commercial affairs of life are being
announced from day to day. And thus we find this class
of the bacteria, which comprises by far the greater number
of species, to be our beuef actors and indispensable servants
both in preventing the accumulation of noxious and harm-
ful substances upon the earth and in really helping to
produce the food which we eat.
The parasitic bacteria, on the other hand, have their
habitat in or upon highly organized living matter, and
exist at its expense. They also produce in their growth
substances called toxins, that are either locally or generally
poisonous or harmful to the organism that is their host.
It is needless to say that it is in this class that we find the
disease germs, or pathogens, as some would call them.
It should not be forgotten, however, that the saprophytes,
in the decomposition of complex organic bodies, may also
produce ptomaines, more or less toxic to animal life. Of
these latter we may instance as good examples the dan-
gerous tyrotoxicon, a by no means uncommon product in
the decomposition of milk, ice-cream, etc., the cadaveric
poisoning of the dissecting-room, etc. But, while these
ptomaines are more or less characteristic of the respective
bacteria that produce them, each varies in its composition
and properties according to the substance upon or in which
it is produced.
We say that an organism is optional when it is at one
time a saprophyte and at another a parasite, or at one time
46 A MANUAL OF HYGIENE AND SANITATION.
aerobic and again anaerobic; and that it is obligate when
it has not this property of changing its nature according
to surrounding conditions.
Considering for the present the pathogenic bacteria
alone, we are naturally brought to the discussion of the
gerni theory, which is, that the exciting cause of each
contagious or infectious disease is some specific parasitic
organism, and that these diseases are communicated only
by the transference to and development of the specific
parasite or germ within or upon the infected individual.
Consequently, such diseases are transmitted from one per-
son to another, or, in some cases, from animals to men, or
vice versa, by means of these micro-organisms, and the
transference is by the air, water, food, or other fomites, or
by direct contact. It is evident that, if facts and knowl-
edge establish the truth of this theory, the prevention of
infectious diseases is greatly simplified, and becomes
merely a matter of combining effective sanitation, of
which we have spoken, with the destruction of the specific
exciting causes, viz., disinfection. Nor is it essential that
we any longer make the distinction between the terms
contagious, infectious, zymotic, and specific, that formerly
obtained, but all may be practically used synonymously.
The first of these terms used to be applied to those diseases
which were thought to be transmitted by direct contact
only, and " infectious ' 7 to those in which the transmis-
sion was by fomites. But we now know that germs of
the former class may be transmitted by air, water, food,
etc., and of the latter by direct contact, though the reverse
is what usually happens in the respective classes. The
term " zymotic" was formerly applied to those diseases
occurring in epidemics, and supposed to be due to fermen-
tative processes; if used at all, it should be given to any
BACTERIOLOGY. 47
disease due to a living germ. The term <f specific " should
only be given to those maladies which have a specific origin
— i. e.j which have been proved to be due solely to a single
organism.
That most communicable diseases are due to such germs
or kindred animal organisms is more than probable, and,
while there are some in which it has not been fully proved,
it is scarcely possible that any of these may arise from
insanitary causes without the presence of a living organism.
Our reasons for believing in the germ theory are based
on empirical and logical facts as well as theoretical
hypotheses. Leaving out, at present, the work already
done, it is evident that the matter that causes a disease,
the contagium, must, when introduced into a susceptible
person or animal, increase in quantity to an enormous
extent. Note, for instance, the amount of positively viru-
lent matter thrown off from a case of smallpox or scarlet
fever, and yet how very little is required to initiate a dis-
ease. No dead chemical substance has the power of being
increased to such an extent by simply finding a lodgement
in a suitable medium. The poison of contagion, whatever
it may be, evidently must have life and the power of
reproduction. Moreover, these causes of disease when
freed from the body may be carried long distances, and
may exist for years, and still retain their power for harm,
only waiting to find a suitable field before beginning to
multiply and cause the same identical malady as before.
Such causes must, therefore, be capable of entering a state
in which vitality is latent or dormant, and in which the
reproductive functions are for a time inactive. But we
do know that the spores of many bacteria, and sometimes
the bacteria themselves, may be carried long distances,
kept long periods of time, and even exposed to consider-
48 A MANUAL OF HYGIENE AND SANITATION.
able extremes of temperature, without being killed or
losing their power of reproduction and rapid multiplica-
tion. Again, we know that substances that are poisonous
to or that prevent the development of these bacteria and
kindred low forms of life, do, when properly applied or
used, prevent or remove the danger of contagion.
There is also in the development and progress of any
infectious diseases a direct analogy to the phenomena of
fermentation, whose causative organisms are of the same
order as these which we are considering; the same rapid
multiplication of cells in suitable media at proper tempera-,
tures, a period of incubation, and then changes in the cul-
ture medium, which, after going on to a certain extent,
check the further growth of the organism in that medium.
What it is in the medium that checks the growth of the
germ, we may not be able to determine a priori, but we
may assume it to be something hostile to the contagium, as
alcohol above a certain percentage is hostile to the yeast-
cell.
Lastly, if the proof of Koch's postulates is essential
to the acceptance of a given micro-organism as the cause of
a given disease; on the other hand, we must believe that
a certain germ is a cause of that disease, if not the only
one, if these postulates be proven about that germ in con-
nection with the disease.
To determine whether a certain organism is or is not
pathogenic it is necessary to experiment on living animals.
To do this we must use pure cultures of the organism and
carry out all our processes, including inoculations and
autopsies, under strictly antiseptic precautions. We must
examine the blood and various tissues of a diseased animal
microscopically; if bacteria be present in any of these, we
must make cultures from them, and if more than one kind
BACTERIOLOGY. 49
of bacteria be present, the various kinds must be isolated
and pure cultures made from each kind. When a pure
culture is at last obtained, it is studied both microscop-
ically and as to its characteristics on various media and at
different temperatures. Finally, healthy animals known
to be susceptible to the disease are inoculated from the
pure culture, and, after the period of incubation, carefully
watched for symptoms of the disease in question. Should
these manifest themselves, the animal is killed and the
blood and tissues carefully examined for the inoculated
organisms.
The postulates of Koch, which are necessary to prove
that a germ is the cause of a given disease, are: 1. The
micro-organism must be found in the blood, lymph, or
diseased tissues of a person or animal sick or dead of the
disease. 2. The micro-organism must be isolated from
the blood, lymph, or tissues and cultivated in suitable
media outside of the animal body. These cultivations
must be carried on through several generations until a
pure culture of the germ is obtained. 3. A pure culture
thus obtained must, when introduced into a healthy animal,
produce the disease in question. 4. In the inoculated ani-
mal the same organism must again be found.
In the cases of many diseases peculiar to human beings
alone the third condition must remain undetermined and
our chain of proof be broken, because we cannot endanger
human health or life by our inoculations. But in diseases
common to men and animals the experiments necessary can
be completely carried out, and where a germ can be proved
to be the cause, according to these postulates, of the malady
in animals, we can also fairly conclude that it is the cause
of the same disease in human beings. The specific germs of
a number of maladies common to man and beast have thus
50 A MANUAL OF HYGIENE AND SANITATION.
been determined, together with those of a large number of
affections peculiar to animals alone.
After infection or the reception of the contagium by a
susceptible animal there is a period of incubation before
the manifestation of the characteristic symptoms of the
disease, which period is variable according to the kind of
germ, and during which the micro-organisms are rapidly
increasing in numbers and their consequent power for evil.
After the pathological process is well under way we shall
find one of two conditions existing, viz., that " in which
the blood is the chief field of activity of the organisms,"
and the vessels of the victim are swarming with the
microbes — in other words, a true septicaemia; or else one
where " the poisonous results are not necessarily accompa-
nied by the growth of organisms in the tissues," these
latter, in all likelihood, not extending beyond the lym-
phatic glands nearest to the point of inoculation — i. e.,
a toxcemia. A good example of the former condition is
furnished by a case of anthrax or of pyaemia, and of the
latter, in diphtheria. However, we shall find in either
condition that if we isolate the peculiar product or toxin
of the specific germ, either from artificial growths upon
culture media, or from the blood or tissues of an animal
sick or dead of the disease, and inoculate this into a sus-
ceptible animal, the general symptoms and results pro-
duced are practically the same as in an ordinary case of
the disease. This goes to prove that the products of patho-
genic bacteria are toxic in character and poisonous to the
tissues, either locally or generally, and that infection must
be accordingly a chemical and toxicological process.
Another point to note just here is that these toxins are
i Abbott, loc. cit.
BACTERIOLOGY. 51
apparently harmful to the bacteria themselves whenever
they exceed a certain amount, as is shown by the fact that
most of the infectious diseases are self -limiting and by the
cessation of growth and even the death of the germs in the
various culture media after a certain length of time. It is
but right to state, however, that there is another possible
explanation of this latter phenomenon, viz., an increase in
the resistance of the infected body to the action of the
germs and toxins, and, in the case of culture media, the
marked change in reaction caused by the bacterial products.
Having thus obtained some knowledge of the exciting
causes of contagious diseases and of how they act, one of
the most important considerations is in relation to the pre-
vention of the incurrence of these diseases by the well,
and to the antagonizing or checking of the further action
of the cause in those already infected. It is well to dis-
infect and destroy disease-germs whenever and wherever
it is possible to do so, but it will be still better so to
strengthen and fortify the human body that the microbes,
even though received into it, will be unable to attack it or
do it harm. That we have the means of producing such
immunity in the case of one disease, at least, is well shown
by the history of vaccination, and the abundant work of
numerous investigators in recent years indicates that the
promise of similar results in many other maladies is by
no means vain. Certain it is that many animals and, in
some cases, men have been rendered apparently immune
to other fatal diseases, and the indications point to the
probability that the human race .will shortly have the same
protection against most of the contagious maladies that it
now has against smallpox.
With the knowledge that immunity to infectious dis-
eases may be produced accidentally or intentionally, and
52 ^ MANUAL OF HYGIENE AND SANITATION.
may be practically applied without a definite understand-
ing thereof, we need not consider the method whereby the
body brings about such immunity. Nevertheless, several
theories have been advanced in the attempt to explain the
phenomenon. Of these two have been practically dis-
proved, viz., the exhaustion theory of Pasteur, which was
that the pathogenic germs in their process of growth in
the body removed some material from the latter necessary
to their existence; and the diametrically opposite retention
theory of Chauveau, which was that the germs produced
some substance which gave immunity as long as it was
retained in the tissues. On the other hand, there are still
strong adherents to both the phagocytosis theory of Metch-
nikoff and the humoral theory of Biichner.
The phagocytosis theory is (t that immunity against
infection is essentially a matter between the invading bac-
teria on one hand, and the leucocytes of the tissues on the
other; that during the first attack of the disease the white
blood-corpuscles gain a tolerance to the poisons of the
bacteria, and so are able to resist the next incursions of
the enemy. " Biichner has apparently shown that the
blood-plasma, especially that of immune animals, is actu-
ally bactericidal to many virulent germs, and he attributes
this effect to the presence in the fluid of certain proteid
substances akin to globulin. These he terms alexins, from
a Greek word meaning to protect. Further, he believes
that they act chemically in causing the death of the disease
germs, and that the increased amount of alexins in the
blood of those who have acquired immunity is brought
about by a stimulation or " reactive change'7 in certain
cells due to the presence of the bacteria or their products.
Moreover, this humoral theory serves to account for the
natural immunity possessed by some individuals and ani-
BACTERIOLOGY. 53
mals, their body juices presumably containing, through
some cause or other, an extra quantity of the protective
proteids.
There is, however, another theory, that of the anti-
toxins, which, in view of recent developments and the fact
that it is the most capable of practical application, is prob-
ably the most important of all. It is well known that the
human system has the power of tolerating or accommodat-
ing itself to the action of almost any toxic substance — pro-
vided the latter be administered in sufficiently minute doses
gradually increased until it can in time withstand quan-
tities that would quickly prove fatal to one unaccustomed
to the poison. Ehrlich has further shown that, with the
alkaloids of certain higher plants, after a certain degree of
tolerance is attained the administration of the drug may
be much more rapidly increased, and that while up to this
point no change occurs in the blood, now, when the toler-
ance becomes so much exaggerated, a new substance is
produced which is capable of neutralizing the poison in
that individual not only, but also in others into whose
blood it may be introduced. Many experiments have
shown that this same production of antidotal or antago-
nizing substances may be brought about by the slow
administration of the toxins of pathogenic bacteria — some-
thing not hard to understand when we remember that the
bacterial toxins are just as much the products of plant-life
as are the alkaloids that Ehrlich used, and very much like
the latter in formula or composition.
On the other hand, the antitoxins, as these new sub-
stances antidotal to the toxins are called, have been found
to be albuminoid in character and very similar to the
nuclei ns. In fact, some attempts have been made to em-
ploy the latter in place of or in conjunction with the anti-
54 A MANUAL OF HYGIENE AND SANITATION.
toxins, with results which have not been altogether without
success and to which reference may hereafter be made.
Much credit must be given to the labors of Behring,
B-oux, Kitasato, and others, for the development of prac-
tical methods of using the anitoxins, methods which are
now recognized as eminently proper and even superior to
any others in the treatment of some of the most virulent
diseases. The great reduction in the mortality from one
disease alone — diphtheria — already attained through the
application of this treatment almost exceeds expectation
and belief, and the promise seems now to be that the
results with respect to tetanus and cholera and other deadly
maladies will be equally brilliant and add further glory
to this new science of bacteriology.
To some it may seem that either the humoral or the
antitoxin theory is identical with the discarded retention-
theory of Chauveau ; but it should be noted that, according
to the latter, the invading microbes themselves produce the
antidote or antagonizing substance, while Biichner's theory
attributes this production to the integral cells of the body,
which furnish the alexins normally in minute quantities to
the blood, and insists that the latter are germicidal to the
bacteria themselves; and, on the other hand, the antitoxins,
though produced by body-cells like the alexins, act chemi-
cally in neutralizing the bacterial poisons, and are depen-
dent upon the prior presence in the body of the toxins and
are a result of its acquired tolerance to the latter. With
alexins or antitoxins it is evident that the immunity will
last as long as these substances remain in the blood.
Nor is there any reason why the phagocytosis, humoral,
and antitoxin theories should not mutually support rather
than tend to discredit one another. There seems to be
good evidence of the phenomena upon which each of the
BACTERIOLOGY, 55
three is based, and, even with our present incomplete
knowledge of the blood and its component parts, it is not
difficult to conceive that while the alexins, and later the
antitoxins, protect the leucocytes by respectively weaken-
ing the vitality of the microbes and neutralizing their
products, the leucocytes, thus guarded and in full vigor,
attack and make way with the bacteria, which have lost
their virulence and power for evil. In other words, if the
production of the toxins of an infectious malady is not
too rapid, all three of these agents may combine to over-
come the enemy and not only to limit the disease but also
to give subsequent immunity for a more or less prolonged
period.
Nevertheless, experience will continue to show that,
whether one or all of these theories may be finally
accepted, or whether new methods by which the body
protects itself may be discovered, sanitation and a con-
dition of perfect health throughout the system are of the
utmost importance in warding off attacks of or securing
immunity from any of the pathogenic organisms, and in
withstanding their ravages, should disease be incurred.
A sound body, therefore, is a most vitally active and not
a passive agent for the prevention of such diseases.
Within a comparatively short space of time the anti-
toxins have been discovered, tried, and apparently practi-
cally adopted by the medical profession of the civilized
world as a safe and efficient means for the prevention or
alleviation and cure of several of our most dreaded dis-
eases. A short account of the usual methods of preparing
them will, therefore, probably not be uninteresting.
In the first place, it is necessary that the toxin of the
disease should be produced, which is commonly done by
growing the specific organism in a peptone-bouillon.
56 A MANUAL OF HYGIENE AND SANITATION.
When this has attained a powerful and definite virulency,
as determined by the effect on small animals of known
weight when inoculated with it, the organisms are de-
stroyed by some germicide, such as trikresol, or more
commonly the bouillon containing the toxins is filtered care-
fully to remove the germs. A small quantity, say one cubic
FIG. 10.
Filter for removing bacteria from fluid culture media.
centimetre, of the filtered bouillon is then injected into a
large animal, such as the horse, which should be in good
health and, preferably, should have been tested previously
by inoculations of tuberculin and mallein to eliminate the
possibility of the presence of tuberculosis or glanders.
The animal manifests the disturbances peculiar to the dis-
ease in question for a few days, but usually in a minor
degree, since the dose was quite small in proportion to its
weight; as soon as recovery is evident, another inoculation
of an increased dose is made, and so on until experiment
shows that the animal can withstand practically an unlim-
ited dose of the toxic bouillon and one which would have
BACTERIOLOGY. 57
been quickly fatal before the first inoculation. This is
evidence that the antitoxin exists in approximately suffi-
cient degree in the blood-serum. A quantity of blood is
then taken with the strictest antiseptic precautions from
the jugular or .other large vein of the animal, the latter
returned to its quarters, and the blood set aside on ice to
coagulate. This done, the clear serum containing the
antitoxin is drawn off, and to it is added a small quantity
of trikresol or other harmless preservative.
It is now necessary to determine the strength of the
serum. The fatal dose of toxin for guinea-pigs is readily
found by experiment. Behring, therefore, suggested, in the
case of diphtheria antitoxin, that the immunizing unit
be taken to be 1 c.c. of a serum of which 0.1 c.c. would
prevent oedema and death in guinea-pigs when injected
simultaneously with ten times the fatal dose of toxin. In
other words, the immunizing unit was to be sufficient to
overcome one hundred times the amount of the toxin
required to kill a guinea-pig.
FIG. 11.
Roux aseptic hypodermic syringe for administering antitoxin.
The antitoxin serums now administered are, however,
much stronger than this normal serum of Behring's, 10
c.c., the amount usually injected, containing from 600
to 2500 or even more immunizing units, the weaker
strength being used for immunizing those who have not
as yet incurred the disease. Much depends upon the
early use of the specific antitoxin in cases of diphtheria,
and probably also for the other diseases for which this
method of treatment will be found valuable. It is not
58 A MANUAL OF HYGIENE AND SANITATION.
to be supposed that the remedy has any power to repair
the organic lesions which have been caused by the action
of the powerful toxins. That the antitoxin treatment is
invaluable cannot be doubted. The statistics of Prof.
Welch, of Johns Hopkins Hospital, founded on a very large
number of diphtheria cases, " show an apparent reduction
of case-mortality of 55.8 per cent.," and where the appli-
cation was made in the first three days of the disease the
mortality was only 8.5 per cent, in over 1100 cases, as
against a mortality of 30 per cent, or more under former
methods of treatment. Another interesting report is that
of the Chicago Department of Health for 1896. In that
city in that year there were 2436 cases of true diphtheria
verified bacteriologically. The antitoxin was adminis-
tered to 2302 of these, with a resultant mortality of only
6.56 per cent., or 151 deaths. Moreover, 2016 other
persons exposed to the disease were inoculated with the
antitoxin in order to immunize them, and of these only
14 subsequently contracted the malady, and none died.
Further comment seems unnecessary.
Another practical method of securing immunity, advo-
cated and employed by several noted investigators, is as
follows : To produce, by cultivating the pathogenic bac-
teria under abnormal conditions, toxins of much less than
normal virulence, and then, after filtration or sterilization
of the latter in order to isolate them absolutely from the
causative microbes, to make a series of inoculations of pro-
gressively increasing strength, and thus directly bring
about a state of accommodation to or protection against the
germ and its toxin without serious risk to the subject.
CHAPTER III.
THE ATMOSPHERE — AIR.
THE composition of the atmosphere surrounding the
earth is remarkably uniform. It is practically always the
same everywhere, provided no obstacle be interposed to
the action of those natural forces by which this uniformity
is maintained. This atmosphere is estimated to be about
forty miles in depth, and its weight-pressure, of which we
have a visible manifestation in the action of the barom-
eter, upon the total surface of the adult human body is
equivalent to that of about fourteen tons. Any consid-
erable variation in this pressure may give rise to distur-
bances of health more or less serious, such as the cardiac
derangements and "mountain sickness'7 experienced by
strangers visiting high altitudes, or the " caisson disease "
of those who work in a compressed atmosphere. In fact,
it is not improbable that some of the vague disturbances
of comfort to which a large class of persons are subject will
hereafter be found to be due to the minor variations in this
pressure which are constantly occurring everywhere.
The average composition of the air in its normal state
is about as follows : Oxygen, 20.96 per cent, by volume;
nitrogen and argon, 79 per cent.; carbon dioxide, 0.04
per cent. ; aqueous vapor, the amount varying with the
temperature; a trace of ammonia, and a variable amount
of ozone, organic matter, sodium salts, etc. The varia-
tion in the percentage of oxygen may extend from 20.87
in towns to 20.98 in pure mountain air or far out at sea;
60 A MANUAL OF HYGIENE AND SANITATION.
in the percentage of CO2, from 0.02 to 0.05. So far as we
know at present, the nitrogen variation is almost infinitesi-
mal. The air is a mechanical, not a chemical mixture, and,
as indicated, there is always some change taking place in
the proportions of the various constituents. However,
the mixture is maintained in its wonderful uniformity by
the interdependent action of plants and animals, and by
the diffusion of gases, the law of which is that " a gas
expands into a space in which there is another gas as
freely and as rapidly as if there were a vacuum/7 Though
this agency, like the other, is continually operating, its
results are greatly facilitated by adventitious air-currents
and by the application of heat. When a gas is thus
diffused it will not separate again from the others under
ordinary circumstances.
Oxygen is the most important of the above constituents.
It supports all animal life; oxidizes, destroys, and renders
harmless organic impurities, and, by oxygenating the blood
and oxidizing the food for our tissues, gives us heat and
energy, the sources of all our thoughts and actions. The
supply to the atmosphere is constantly maintained by the
higher plant life, which decomposes carbon dioxide and
gives off oxygen to the air. In man the greatest limit of
life without oxygen or air is about four minutes. A
decrease in the proportion of oxygen in the air does not
manifest itself by untoward symptoms until there is less
than 13 per cent, by volume ; then, as it falls lower and
lower, the respirations become slower, deeper, and more
difficult, less oxygen is absorbed by the blood, and there
are dyspnoea, asphyxia, and death. This may occur within
a short time when the percentage goes below 8 per cent.,
and asphyxia supervenes very rapidly when there is as
little as 3 per cent, of oxygen.
THE ATMOSPHERE— AIR. 61
The main function of the nitrogen of the atmosphere
seems to be to act as a diluent and to prevent the too
energetic action of the oxygen. We know now, however,
that by the aid of certain bacteria at least one family of
plants, the leguminosae, is able to take nitrogen almost
directly from the air and to store it up for animal use in
the form of proteids. The ammonia ever present in the
air is also a source of nitrogen for some plants.
The gaseous element, argon, recently discovered by
Lord Kayleigh and Prof. Ramsay, comprises about 1 per
cent, of what has heretofore been considered atmospheric
nitrogen. Thus far little is known concerning it except
that its atomic weight is probably somewhat less than 40,
its density about 20, and that it is very inert, though
Berthelot has succeeded in making it combine with nascent
vapors of benzene under the influence of an electrical
discharge. That it is a constant component of the atmos-
phere for some definite purpose is more than probable,
but what this purpose may be is, as yet, unknown.
The carbonic acid present in pure air is of no direct use
to animals, but is essential to the support of vegetable life,
furnishing the carbon necessary for the formation of the
carbohydrates and proteids, which are, next to water, the
main constituents of plants. The proportion of carbonic
acid in pure air varies somewhat from time to time, owing
to the changing conditions. It is washed out of the air
by rain, and there is, therefore, less after a heavy storm ;
plants absorb it by day, and some give off a slight quan-
tity of it by night; the strata of the atmosphere near the
ground receive an excess of it, from the soil-air; it is a
constant product of the decomposition of organic matter
by saprophytic bacteria, etc. Though heavier than air, it
62 A MANUAL OF HYGIENE AND SANITATION.
is comparatively evenly distributed through the atmosphere
by the force of diffusion.
The normal proportion in the atmosphere varies from
0.02 per cent, to 0.05 per cent., but we may take the
average to be about 0.04 per cent. Should, however, any
important tests of the amount in-doors be required, the
percentage in the out-door air at that particular time and
place should also be determined for the sake of accuracy.
Within the limits just given the carbonic acid cannot be
considered as an impurity of the atmosphere, for it is ever
present in the air, and is as necessary to plant life as oxy-
gen is to animals. It is derived from the combustion of
carbonaceous materials, from the exhalations and excre-
tions of animals and men, and, as was indicated, in large
measure from the action of the saprophytic bacteria and
also of the budding fungi upon organic matter. More-
over, any excess above the percentage given is to be re-
garded not so much as an impurity as an indication that
certain processes are at work, which, by their products,
may make the air impure and unsafe for human use.
The amount of aqueous vapor in the atmosphere varies
constantly because the factors governing it — condensation
and evaporation— are constantly in action, these depend-
ing, of course, mainly upon the continual variations in
temperature. There is probably never a perfectly dry
air, unless it is made so artificially, and precipitation
occurs the moment the degree of complete saturation is
exceeded. The range of relative humidity is probably
from 30 per cent, to 100 per cent., this being equivalent,
according to the temperature, to a water content of from
one to twelve or fourteen grains to the cubic foot of air.
The best proportion for health has not been experimentally
THE ATMOSPHERE— AIR. 63
determined, but is generally considered to be from 65 to
75 per cent.
In all normal air there is at least a trace of ammonia,
either free or combined, a small amount of the salts of
sodium (especially near the sea) and of other minerals, and
a trace of organic matter. This last is part of the animal
and vegetable debris of the earth ; when it rises above a
trace it is to be treated as an impurity, as should any
excess of ammonia.
Minute particles of almost every substance known are
being constantly thrown off into the atmosphere, and it is
only the unceasing action of nature's purifying powers
that keeps the proportion within the limits of safety to
the human race. Solid particles, lifted up by the winds,
fall to the earth again, or, if organic, are partially oxidized
and decomposed by the oxygen and ozone. The gases are
diluted and diffused so as to be no longer harmful, or are
decomposed, or are washed back to the earth by rain or
snow. The great volume of carbonic acid is kept within
bounds by the action of the vegetable world. The natural
purifiers of the atmosphere, therefore, are the force of
gravity, diffusion, dilution by the air itself, winds, oxida-
tion, rain, and the action of plant life; arid so exactly are
these related to their work that never, when they have
opportunity to act, does the composition of the air vary
much from the normal for any great length of time.
The impurities in the atmosphere that are especially
liable to have a deleterious influence upon health may be
classed as follows : 1. Suspended matters. 2. Gaseous
and semi-gaseous substances, including : 3. Those especi-
ally due to respiratory, combustion, and decomposition
processes and which are particularly liable to contaminate
the air of dwellings or inhabited apartments.
64 A MANUAL OF HYGIENE AND SANITATION.
The most important suspended matters are sand, dust,
soot, pollen of various plants, micro-organisms of all kinds,
particles of epithelia, and other excreta thrown off from
animal bodies, and dusts or finely divided substances char-
acteristic of certain trades or industries. These may do
harm by clogging up the air vesicles of the lungs, and thus
obstructing respiration, though it is doubtful whether their
action is ever so mild or simple; by their irritant action upon
the respiratory passages; by being in themselves poisonous
or hostile to the system, or, as in the 'case of micro-organ-
isms, by the power they have in the causation of disease.
Such germs may lodge in the respiratory passages to do
their harm, or may be swallowed, and so cause maladies,
such as typhoid fever or cholera, which primarily affect
the digestive tract.
It is, however, questionable whether pathogenic organ-
isms, especially the bacteria, are commonly to be found
dissociated from other substances floating in the air.
Experiments by Cornet and others seem to show that such
microbes are apt to be adherent to dust particles, particu-
larly those of organic nature, and it is probable that free
bacteria could not long maintain their vitality in the out-
door atmosphere deprived of nutriment and exposed to
the action of light and oxygen. Beside, they are so quickly
diluted and reduced in numbers in proportion to any
reasonable volume of air, that the occasions must be rare
indeed when they could there cause disease. In-doors,
especially where ventilation is neglected, the case is differ-
ent, and there is no doubt that the air frequently becomes
the carrier of the dangerous pathogens.
We must also make a distinction as to whether the other
solid impurities are found in the out-door air or in enclosed
spaces; and, if in the latter, whether in healthy dwellings,
THE ATMOSPHERE-AIR. 65
in sick-rooms and hospitals, or in workshops and factories.
Out-of-doors, dust, sand, soot, pollen, waste dirt from dwell-
ings, street refuse, and the remains of plant and animal
life will predominate; in-doors the particles will be more
limited in variety, but not in importance. Among them
will be epithelium and other cells, possibly pus-corpuscles,
hair, bits of clothing, upholstery, food, etc. One might
also find arsenical or other poisonous dust from wall-paper
or paint. In hospitals there will probably be pus-cells.,
mycelia, bacteria, etc. Mills, factories, and mines have
their special atmospheres filled with particles peculiar to
the materials or occupation, which have a marked effect
for harm, in many cases, on the health of the workers.
The gaseous and semi-gaseous impurities of most impor-
tance are those resulting as products of human respiration
and cutaneous exhalations, as products of combustion,
peculiar gases from sewer- or soil-air, organic emanations
and vapors from decomposing animal and vegetable mat-
ter, and the volatile substances that characterize the vari-
ous atmospheres in and about gas-works, factories, and
other industries. Chemically, they may be classified as the
various compounds of carbon with oxygen or hydrogen,
and of these with sulphur, and as ammonia .compounds,
volatilized minerals and mineral acids, and many gaseous
and semi-gaseous matters of organic nature but indeter-
minate composition.
Inasmuch as certain of these impurities, viz., human
exhalations, combustion products, and not infrequently
the so-called sewer-gas, are particularly liable to be found
together as contaminants of the atmosphere of inhabited
rooms and dwellings, it will be advisable to consider them
in a class by themselves, and to study their effect upon
health both collectively and singly. The volatile excreta
5
66 A MANUAL OF HYGIENE AND SANITATION'
from the lungs and skin are carbonic acid, aqueous vapor,
and a considerable amount of nitrogenous organic matter,
to which the term " crowd-poison" is sometimes given. As
products of combustion from the ordinary lighting and
heating apparatus of dwellings we may have carbonic acid
(dioxide), carbonic oxide (monoxide), sulphur dioxide, am-
monia (with possibly its sulphide), and aqueous vapor. Of
sewer-gas and soil-air we shall speak later.
Carbonic-acid gas, contrary to the general opinion, can-
not be said to be directly poisonous or harmful to health
in the proportions in which it is likely to be found in
any dwelling or inhabited apartment. Although present
to the extent of not over 0.05 per cent, in normal out-door
air, numerous experiments indicate that both men and
animals may inhale much larger proportions than this with-
out apparent harm, provided the percentage of oxygen in
the air be maintained at or above the normal; an increase
of the carbonic acid from other sources than respiration
and combustion seems to have no appreciable effect upon
the system till it reaches more than 2 per cent. , and many
work daily in atmospheres containing almost this amount
as a result of their peculiar occupations, and dyspnoea does
not begin to occur, and then only in some, until the per-
centage goes above 3 or 4 per cent. In quantities above
these figures there is much difference of opinion as to the
effect of the gas upon the human economy, and the writer
is not aware that it has ever been determined beyond
question as to just what percentage is fatal. Prof. Parkes
states the lethal proportion to be from 5 to 10 per cent. ;
while another states that animals may be kept for a long
time in an atmosphere in which there is a high percentage
of carbon dioxide, provided the percentage of oxygen be
increased at the same time. Dr. Hime says that et it may
THE ATMOSPHERE— AIR. 67
be assumed that 10 or 20 per cent, is a dangerous
amount, m but Wilson2 shows that air having from 25
to 30 per cent, may be inhaled with impunity. It is
to be understood that the above percentages are all by
volume.
According to his size, an adult man at rest absorbs from
fifteen to eighteen cubic feet of oxygen and exhales from
twelve to fourteen cubic feet of carbonic acid in twenty-
four hours. Reichert3 says: "The amount of O varies from
600 to 1200 grammes (15 to 30 cubic feet) per diem, and
that of CO2 from 700 to 1400 grammes (12.5 to 25 cubic
feet) — approximate averages being about 750 grammes of
O and 875 grammes of CO2." The minimum excretion
may, therefore, fairly be taken to be about seven-tenths of
a cubic foot of carbonic acid for adult men and six-tenths
of a cubic foot for women, or for each person of a mixed
assemblage. Now, it is evident that it would require many
hours before a room of, say, 1000 cubic feet capacity would
lose enough oxygen to or gain sufficient carbonic acid from
a single adult occupant to produce even the slightest appar-
ent harmful results upon him, even though any ingress of
fresh air were absolutely prevented; and yet experience
tells us that long before the lapse of time necessary to
thus add sufficient carbonic acid to do harm, the air of
such a room will become exceedingly foul and actually
harmful to health. Moreover, carbonic-acid gas is odor-
less, while the air of inhabited, unventilated rooms is
characterized by a decidedly offensive smell that remains
for some time, even after adequate ventilation has been
secured and when chemical tests show the percentages of
1 Stevenson and Murphy, vol i. p. 945.
2 American Journal of Pharmacy, 1893, p. 561.
3 American Text-Book of Physiology, p. 536.
68 A MANUAL OF HYGIENE AND SANITATION.
carbonic acid to have been reduced to nearly the normal.
" The chemical analyses of the air of over-crowded rooms,
and the experiments upon animals made by many investi-
gators, indicate that the evil effects observed are probably
not due to the comparatively small proportions of carbonic
acid usually found under such circumstances. . .
The proportion of increase of CO2 and of diminution of
oxygen which has been found to exist in badly ventilated
churches, schools, theatres, etc., is not sufficiently great to
satisfactorily account for the great discomfort which such
conditions produce in many persons, and there is no evi-
dence that such an amount of change in the normal pro-
portion of these gases has any influence upon the increase
of disease and death-rates which statistical evidence has
shown to exist among persons living in crowded and
unventilated rooms. JM
Therefore, it must be something other than carbonic
acid that dangerously pollutes the air of our dwellings and
necessitates the provision of some system of ventilation.
However, with our present knowledge, we cannot say that
a diminution of oxygen and an increase of carbonic acid
in the atmosphere which one breathes habitually does not
tend to lower the general tone and perhaps the bactericidal
powers of the body, and thus render it more susceptible
to deleterious influences; and there is some evidence that
as the carbonic acid in the atmosphere increases there is
a lessening of the amount of this gas excreted from the
body; so that, on general principles, it will be always
wiser to use every reasonable means to maintain the
normal proportion of the various gases in the atmosphere.
* " The Composition of Expired Air and its Effect upon Animal Life," Drs.
Mitchell, Billings, and Bergey, No. 989, vol. xxix., Smithsonian Contributions to
Knowledge.
THE ATMOSPHERE -AIR. 69
Aqueous vapor is another of the substances excreted con-
tinually from both the lungs and the skin, but it is obvious
that, in itself, it cannot be directly harmful to the system,
for we find it ever present in all natural atmospheres, and
are continually replacing its loss from our bodies by imbi-
bition. The quantity daily thrown off from the lungs and
skin will depend on the temperature and humidity of the
atmosphere, the quantity of air inspired and water im-
bibed, and many other factors, but under ordinary con-
ditions the average excretion will be from 100 to 1700
grammes (about 3.5 to 60 fluidounces), though increased
exertion might cause even the larger amount to be greatly
exceeded. It is accordingly possible that this large quan-
tity of moisture, tending to saturate an atmosphere already
humid, might act indirectly upon the system by preventing
evaporation from the skin, and thus reflexly checking the
excretion of the waste matters by the sweat-glands, the
retention of these wastes in the system probably helping
to produce the depression, headache, and other symptoms
experienced by those breathing foul air. It has been no-
ticed that these symptoms due to foul air are more readily
manifested when the temperature of the atmosphere is
much below or much above the usual room temperature of
65° to 70° F. At low temperatures it is easy to saturate
the air, and beside, the excreting action of the skin is much
lessened by the cold; at high temperatures the humidity
is often already near the saturation point, while the exter-
nal heat tends to increase the quantity of water given off
by the lungs and skin. "At high 'temperatures the respir-
atory centres are affected where evaporation from the skin
and mucous surfaces -is checked by the air being saturated
with moisture — at low temperatures the consumption of
oxygen increases, and the demand for it becomes more
70 A MANUAL OF HYGIENE AND SANITATION.
urgent. m At 70° F. the aqueous vapor from an adult
body would completely saturate from 350 to 600 cubic
feet of air having the not unusual relative humidity of
75 per cent., while at 80° F. an equal or even greater
volume would doubtless gain its maximum of moisture
from the increase of perspiration due to the extra heat.
The third contaminant given to the air from human
bodies is an indefinite volume of offensive organic matter,
and until quite recently this has been looked upon as by
far the most harmful part of animal exhalations. But
lately a number of experiments by various investigators
have seemed to indicate that this organic effluvium is not so
dangerous as it has hitherto been considered, and that part,
at least, of the symptoms due to air vitiated by respiration
is to be attributed to the conditions already mentioned,
viz., a decrease of oxygen and an increase of carbonic
acid, heat, and moisture. It is also doubtful whether
much, if any, of this organic matter comes from the lungs
of healthy persons. " In ordinary quiet respiration, no
bacteria, epithelial scales, or particles of dead tissue are
contained in the expired air. . . . The cause of
unpleasant, musty odors in rooms may in part be due to
volatile products of decomposition from decayed teeth, foul
mouths, or disorders of the digestive apparatus, and in part
to volatile fatty acids given off with or produced from the
excretions of the skin , and from clothing soiled with such
excretions. ":! However, whatever may be the exact source
of this contamination, we know this concerning it, — that it
is decidedly offensive to the sense of smell, that it is
organic and nitrogenous, yielding ammonia, darkening
sulphuric acid, decolorizing permanganate of potash, and
1 Drs. Mitchell, Billings, and Bergey, loc. cit.
2 Ibid.
THE ATMOSPHERE-AIR. 71
rendering offensive pure water through which vitiated air
has been drawn. Moreover, it must in fairness be stated,
that, in spite of the later experiments, it has seemed to such
careful investigators as Brown-Sequard, D' Arson val, Mer-
kel, and others, to be directly poisonous to lower animals.
In general, it is given off proportionately with the carbonic
acid from the body, though this rule is not infallible; it is
apt to be unevenly distributed throughout the atmosphere
of the apartment, and is probably, therefore, not truly gas-
eous, but more like an impalpable dust; it oxidizes but
slowly, being evident for some time after fresh air has
been admitted and the carbonic acid has been almost re-
duced to the normal, and, while neither condensed nor dis-
solved in the aqueous vapor from the body, it is especially
attracted and retained by hygroscopic substances, such as
wool, paper, feathers, etc. Its smell is generally percep-
tible when the respiratory carbonic acid reaches 0.03 or
0.04 per cent., sometimes before this point is reached,
especially in sick-rooms or hospital wards, and is decid-
edly offensive when the total carbonic acid approaches
0. 1 per cent.
The most important of the impurities resulting from
the combustion of coal, the principal fuel substance, are
soot and tarry matters (to the extent of 1 per cent, of the
coal consumed), carbon monoxide and dioxide, aqueous
vapor, and more or less ammonium sulphide, carbon disul-
phide, hydrogen sulphide, sulphur, sulphur dioxide, and
sulphuric acid. The relative amounts of the oxides of
carbon — as well as of the other gases — will depend upon
the perfection of combustion; "-but it has been calculated
that for every ton of coal burnt in London something like
three tons of carbon dioxide are produced," and as that
city's coal consumption is over 30,000 tons per diem, we
72 4 MANUAL OF HYGIENE AND SANITATION.
can see that its atmosphere must receive the enormous
daily contamination of 300 tons of soot and 90,000 tons
of carbonic acid. No wonder they have an occasional fog
there !
The combustion products of wood are in the main
simply carbon monoxide and dioxide, and water, while
those of coke and of gas are practically the same as of
coal. From our heating apparatus, if properly constructed
and arranged, these products pass off almost directly to
the exterior of our dwellings and are rapidly dissipated, in
spite of their excessive volume, for " diffusion and the
ever-moving air rapidly purify the atmosphere from car-
bon dioxide," and, in fact, from the others also, with the
exception of the soot and tarry products.
Should, however, combustion be incomplete, or should
the stoves or other heaters be imperfect, the gases may
seriously or even dangerously contaminate the house-air,
the deadly carbon monoxide being particularly liable to
leak not only through the crevices but actually through
the heated cast-iron plates, etc., of stoves and furnaces.
Theoretically, a pound of coal requires 160 cubic feet of
air for its complete combustion, but practically from one-
half to as much more must be supplied.
On the other hand, practically all the devices for arti-
ficial illumination, with the exception of the incandescent
electric light, give off their combustion products, which
are much the same as those from coal, directly to the air
which surrounds them, and this contamination is, conse-
quently, a positive factor in the vitiation of in-door air.
" Every cubic foot of coal-gas yields, on combustion,
roughly, half its own volume, or 0.52 cubic foot, of car-
bon dioxide, and 1.34 cubic foot of water vapor," beside
some little carbon monoxide when ordinary burners are
THE ATMOSPHERE— AIR.
73
used. " Speaking generally, it may be said that each cubic
foot of gas burnt per hour from the ordinary burners viti-
ates as much air as would be rendered impure by the res-
piration of an individual; it, at the same time, will raise
the temperature of 31,290 cubic feet of air 1° F., and
yields 217 calories (a kilogramme of water heated 1°
C.) or 860 British heat-units (a pound of water heated
1° F.)."1
The following table2 will indicate the influence of various
lighting agents with respect to the condition of the room-
air:
^8
Sg
I8
fi
Oxygen
removed.
CO2 pro-
duced.
Moisture
produced.
•6
IIP*
111 III
gop. £0>8S
Cu.ft.
Cu.ft.
Cu.ft
Tallow candles .
2200 grains
16
10.7
7.3
8.2
1400 12.0
Sperm candles .
1740
16
9.6
6.5
6.5
1137
11.0
Paraffin oil lamp
992 "
16
6.2
4.5
3.5
1030
7.5
Kerosene oil lamp .
909 « :
16
5.9
4.1
3.3
1030
7.0
1
Coal gas, No. 5, batwing
5.5 cu. ft.
16
6.5
28
7.3
1194
5.0
burner.
Coal gas, Argand burner .
4.8 " "
16
5.8
2.6
6.4
1240
4.3
Coal gas, regeneration
3.2 " "
-32
.
3.6
1.7
42
760
2.8
(Siemens) burner.
Coal gas (Welsbach incan- 35" "
descent).
50
4.1
1.8
4.7
763 3.0
Electric incandescent light
0.3 lb coal
16
0.0
0.0
0.0
37
0.0
From this table it will be learned that the incandescent
light is the most satisfactory from a hygienic point of view,
and there is no doubt that its very general introduction of
late has done much toward removing a constant source of
vitiation, especially in those rooms of buildings which
require much artificial light, and are at the same time
Notter and Firth : Treatise on Hygiene, p. 140.
2 Ibid., p. 141.
74
MANUAL OF HYGIENE AND SANITATION.
difficult to ventilate. It is said that in a large bank in
London, in which several hundred persons are employed,
the absences on account of illness have been so far reduced,
apparently by the introduction of the incandescent electric
light, that the extra labor gained has more than paid for
FIG. 12.
Chimney.
Shade Support.
Mantle.
Mantle Support.
Chimney Support.
Gauze Tip.
Gas Spreader.
Corrugated Cap.
antle Carrier.
Centre Tube.
Bobesche Support.
Gallery.
Bunsen Tube.
Air Shutter.
.Adjustable Check.
Welsbach light.
the increased cost of lighting. The electric arc light is
said to form nitric acid; but even so, its effects are not so
harmful as those of the ordinary gas-burner, or lamp, or
candle. Next to the incandescent electric light in impor-
tance are the Welsbach and Siemens gaslights; but of
THE ATMOSPHERE-AIR. 75
these the latter has not the illuminating power, nor is it so
fitted for house use as is the former. The Welsbach light
makes use of the Bunsen flame (in which, by the way, the
carbon of the gaseous fuel is completely consumed and
converted into carbonic acid) to render incandescent a
non-combustible mantle or network, made of the salts of
certain rare earths which have the property of becoming
intensely luminous when sufficiently heated. It gives a
very white light of great illuminating and considerable
actinic power, and of practically unvarying intensity. In
fact, this quality of steadiness, in which it surpasses even
the incandescent electric light, is by no means the least of
its hygienic advantages, since such steadiness is an impor-
tant factor in the conservation of the eyesight.
Sewer-Gas and Soil- Air. What is commonly called
sewer-gas is but a mixture of a number of gases, such
as carbonic acid, carburetted hydrogen, ammonium and
hydrogen sulphide, nitrogen, etc., together with a consider-
able amount of fetid organic matters, the volatile or semi-
volatile products of animal and vegetable decomposition,
varying according to the condition of the sewer, the kind of
matter received therein, the amount of surplus water, etc.
The air from a closed cesspool may be extremely foul and
poisonous, so much so that the emanations have not infre-
quently brought death to those who inhaled them in full
concentration; on the other hand, the atmosphere of a prop-
erly constructed and well-flushed sewer may be almost as
pure as that above the surface. Bacteria are present in
varying numbers, with always the possibility of some of
them being the germs of specific diseases. But fresh sewage
is not so likely to contaminate the air above it with these
microbes as that in which decomposition has begun, since
Frankland has shown that solid or liquid particles are not
76 A MANUAL OF HYGIENE AND SANITATION.
liable to be scattered into the air by any disturbance the
sewage is likely to be subjected to until gases of decom-
position are produced. The bursting of bubbles of the
gas on the surface may then throw the bacteria into the
sewer-air. It has also been shown that " bacteria can
undoubtedly grow up the sides or walls of damp nutrient
sewers, and if these latter become at all dry, air currents
readily detach and disperse them."
Another class of impurities that may at times be found
in the air of dwellings are those coming from the soil and
soil-air. The soil, in hygiene, refers to all that portion of
the earth's crust that can in any way affect the health.
All soils contain more or less air — soft sandstones from
20 to 40 per cent., loose sands from 40 to 50 per cent.,
and loose soils often many times their actual volume
of air.
As the soil is the recipient of most of the solid and
liquid waste of all animal and vegetable life, and as the
myriads of saprophytic bacteria that inhabit its upper
strata are constantly working to convert this dead organic
matter into simpler compounds suited to the nourishment
of plant-life, the soil-air, taking the atmosphere above as
a standard, will usually be far from pure. It is rich in
carbonic acid and in organic vapors and gases, while the
proportion of oxygen seems to be always less than that
of the air above-ground. Moreover, the carbonic acid
increases and the oxygen decreases the deeper below the
surface the sample is taken. As much of the carbonic
acid evidently is derived from the organic pollutions, it
might be supposed that this gas could be taken as an index
of the degree of the latter, and so it might if other con-
ditions, such as permeability of soil, rate of circulation,
etc., were always the same. But they are not, and so the
THE ATMOSPHERE— AIR. 77
composition of the soil-air is practically not the same for
any two places, nor for the same place at different times.
It is constantly in circulation, even to a considerable
depth, but there is a hinderance to its free movement and
diffusibility, and this, together with the great variation in
the distribution of oxidizable and other contaminating
matters, causes the variations in its composition. The
carbonic acid, therefore, cannot be taken as an index of
the relative purity. Owing to evaporation from the
ground- water, the soil- air is always quite humid, and,
according to some writers, may also be laden with bacteria
and other light substances lifted up by the ascensional
powers of evaporation.
The forces that maintain the circulation of the ground-
air are the wind, the daily change of surface temperature,
the fall of rain, and, especially in winter, the local and
artificial conditions of civilization. A very slight wind
will drive the air through the soil for long distances, the
rise and fall of the ground-water has its obvious effect,
and the movement due to even slight changes of tempera-
ture is likely to be quite extensive and positive.
As sewage, house-wastes, and dirt of all kinds are par-
ticularly liable to contaminate the soil about any used
dwelling, the air of that soil will be more than likely to
be impure, and care must be taken that it is not drawn up
into the house. This is especially apt to happen in cold
weather when the house fires are lighted and the indoor
air is thus made much warmer than that outside, the
tendency then being for the soil-air to pass, if possible,
through the cellar walls and floors. These should be
made as near air-tight as possible, and special attention
should be given to the space underneath and about the
furnaces. As an instance of the importance of these pre-
78 A MANUAL OF HYGIENE AND S ANITA TION.
cautions, Dr. Hime1 gives an account of the fatal poison-
ing of four persons. Sufficient illuminating (coal) gas was
drawn through fifteen feet of soil and the foundation walls
of the dwelling from a broken pipe, although there were
only eight or ten inches of tramped earth above the latter
and the only aspirating force was the difference of temper-
ature within and without the house.
There is no direct evidence that the emanations from
bone-yards, soap-factories, garbage-incinerators, etc., are
really harmful to health, but they may be very decided
nuisances to those living near by, and all such places
should be properly controlled by the proper sanitary
authorities.
The atmosphere of mines and other excavations is sub-
ject to contamination by the excess of carbonic acid in the
soil-air, by gases from fissures in the rock and from blast-
ing agents, and by the products of respiration from men
and animals working in the mines, etc. The air in the
holds of ships is also likely to be foul, owing to the diffi-
culty of changing it sufficiently often, and frequently also
to the insanitary character of the cargoes. In such cases
proper ventilation should be secured by all means avail-
able, and special care taken that the impure air does not
affect passengers or crew.
Diseases Caused by Impure Air. As a rule, the
human system has the power of accommodating itself,
through habit, to withstand influences which, in one unac-
customed to them, would soon produce serious results. But
in spite of this, if the body be exposed for any consider-
able length of time to conditions of impurity or deteriora-
tion in its supply of air, water, or food, such conditions
1 Stevenson and Murphy : Treatise on Hygiene, vol. i. p. 949.
THE ATMOSPHERE— AIR. 79
will always tend to undermine health and increase the
susceptibility to disease, even though they cause no more
serious results. ' ' Statistical inquiries on mortality prove
beyond a doubt that of the causes of death which are
usually in action, impurity of the air is most important.
No one who has paid any attention to the condition of
health, and the recovery from disease of those persons
who fall under his observation, can doubt that impurity
of the air marvellously affects the first, and influences, and
sometimes even regulates, the second. . . . The air
may affect health by variations in the amount or condi-
tions of its normal constituents, by differences in physical
properties, or by the presence of impurities. While the
immense effect of impure air cannot be for a moment
doubted, it is not always easy to assign to each impurity
its definite action. The evidences of injury to health
from impure air are found in a larger proportion of ill
health — L e., of days lost from sickness in the year — than
under other circumstances; an increase in the severity of
many diseases, which, though not caused, are influenced by
impure air, and a higher rate of mortality, especially
among children, whose delicate frames always give us the
best test of the effect of food and air."1
The definitely marked diseases caused by the solid im-
purities in the atmosphere are almost all such as affect
the respiratory passages and organs, with the possible
exception of those engendered by specific bacteria and
other minute organisms. Much, therefore, depends upon
the physical character of the /dust and solid impurities.
Soft particles and those with edges smooth and rounded,
like soot and coal-dust, may apparently do nothing more
1 Stevenson and Murphy : vol. i. pp. 121 and 122.
80 A MANUAL OF HYGIENE AND SANITATION.
than clog up the air vesicles and finer bronchial tubes, and
in this way diminish the area of lung tissue exposed to
the inspired air, although it is questionable whether any
foreign matter in the lungs does not cause more or less
actual irritation. With most of us, however, such impuri-
ties are of little account if pains be taken to develop the
full respiratory capacity of the chest; but where the air
is heavily charged with such dust, it has a real effect upon
health and duration of life. In 1862 Sir John Simon
stated that with one exception " the 300,000 (coal) miners
of England and Wales break down as a class prematurely
from bronchitis and pneumonia, caused by the atmosphere
in which they live. The exception is important. The
colliers of Durham and Northumberland, where the mines
are well ventilated, do not appear to suffer from an excess
of pulmonary diseases, or do so in a slight degree only/7
Happily, since this was written satisfactory ventilation
systems have been placed in most of the collieries of Eng-
and, and the condition of the miners correspondingly im-
proved; but coal miners are still, as a class, particularly
liable to bronchitis, pneumonia, asthma, emphysema, and
fibrosis (fibroid phthisis), though they seem to be but
slightly subject to tuberculosis of the lungs or other
organs.
On the other hand, if the particles of dust in the air are
hard, angular, and sharp, the lung-tissues are readily lacer-
ated, inflammatory processes are quickly set up, and the
opportunity for the inoculation of tubercle bacilli and other
disease-germs is very great. The mortality from tuber-
cular phthisis among metal miners, needle-cutters, steel-
and tool-grinders, cotton-spinners, etc., is remarkable;
though they are also especially subject to asthma and
emphysema. Among Cornish tin miners, 68 per cent, of
THE ATMOSPHERE-AIR. 81
all sick are consumptive; of needle-makers, over 60 per
cent.; of flint- and glass-cutters and polishers, and of
grindstone makers, from 80 to 90 per cent., etc. It is
said that a mixture of minerals and metallic dust seems
to be more harmful than metallic dust alone, perhaps
because of the increased clogging of the air-vesicles by the
mineral matter.
Likewise, with other occupations where there is much
irritative dust floating in the air, the effect upon the
health of the worker is marked, and we will find lung
troubles prevalent and many sick and dying from phthisis,
as, for instance, among cotton-spinners, flax- and hemp-
dressers, pottery-makers, etc. Bad ventilation, accumula-
tions of noxious gases, improper habits, insufficient dis-
infection of sputa, and often the excessive humidity of
the air necessary in some of these pursuits, doubtless have
something to do with the high sick- and death-rates, but
withal, the marked effect of the solid atmospheric impuri-
ties cannot be denied. %
Again, workers in poisonous metals, compounds, or
gases, such as paintmakers and painters, type-setters,
gilders (using mercury), brass-founders, and coppersmiths,
etc., are subject to the respective poisons and the symptoms
produced by them, with a correspondingly increased mor-
tality.
Among the diseases that may be caused by the inhala-
tion or swallowing of specific micro-organisms floating in
the atmosphere are erysipelas, measles, scarlet-fever, diph-
theria, whooping-cough, infectious pneumonia, phthisis and
other forms of tuberculosis, and very probably epidemic
influenza; and, although the germs of cholera, typhoid
fever, and yellow fever are usually carried by the drink-
ing-water or food, they do sometimes find their way into
6
82 A MANUAL OF HYGIENE AND SANITATION.
the system from a contaminated atmosphere. Malaria
also is now practically proven to be due to a minute
organism, which, though not one of the bacteria, and
though usually introduced by the mouth with the drink-
ing water, is undoubtedly often present in the air of mala-
rial districts, and may be carried long distances thence by
the winds.
Lastly, the spores of certain fungi, which have been
found in the air of hospitals and elsewhere, are known to
cause skin diseases, such as the tineas and favus in men;
and it is almost as certain that the irritating or poisonous
pollen of certain grasses and other plants have much to
do with the causation or aggravation of such maladies as
hay- and rose-fever.
From what has already been said, it will be surmised
that it is scarcely possible, at present, to specify the exact
effect upon the health of each of the impurities given to
the air by the human body, and that the symptoms ob-
served to be due to air thus vitiated are very probably an
evidence of the combined action of these factors rather than
of any one of them singly. However, the writer feels that
the headache and oppression so commonly experienced are
often fairly attributable to the increase in the temperature
and humidity; that the disturbed nutrition and febrile
condition, lasting for hours and sometimes days after
exposure to air thus vitiated, are either effects of the
organic matter acting as a poisonous waste when taken
into the system, or results of the suppression of cutaneous
excretion dependent upon the high content of moisture in
the air; and that the respiratory carbonic acid in itself
can but rarely have much influence upon comfort or health.
If the respiratory and cutaneous vitiation be sufficient to
produce any acute effects, the immediate symptoms will be
THE ATMOSPHERE— AIR. 83
a discomfort and sense of oppression, followed by headache
and not rarely nausea and a rather decided rise of tem-
perature, all three of which may last for some time, even
after going into perfectly pure air. Those who habitually
live in such an atmosphere are almost uniformly languid,
pallid, and anaemic, subject to headaches, nausea, and loss
of appetite, and often to skin eruptions and disorders, and
are undoubtedly markedly predisposed to phthisis, pneu-
monia, bronchitis, scrofula, rachitis, etc. Moreover,
such an atmosphere apparently favors the rapid spread,
increases the severity of and retards the convalescence
from such diseases as diphtheria, scarlet fever, measles,
typhus, smallpox, etc. This may be due either to the
accumulation or to the actual multiplication by growth of
the disease germs in the foul air, or to its causing a
decrease of bodily resistance and an increase in predispo-
sition to such maladies.
When the proportion of impurities is very great, the
results may be very serious and even fatal, as in the well-
known cases of the " Black Hole of Calcutta;" of the
prison in which 300 captives of war were crowded after
the battle of Austerlitz (260 dying very soon after being
placed therein), and of the steamer " Londonderry," in
which, of 200 steerage passengers who were temporarily
crowded into a cabin (18 x 11 x 7 feet) during a storm,
seventy-two were dead and others dying when the cabin
was opened.
As regards the influence of combustion-products on
health, it will suffice to detail the symptoms produced by
the inhalation of the various gases. It will be difficult to
show that these gases, together with the coincident soot,
have any general effect upon health when escaping into
the out-door atmosphere, even when produced in such
84 -4 MANUAL OF HYGIENE AND SANITATION.
enormous quantities in cities as has been already indicated.
It is possible that the sulphur dioxide and other sulphur
gases might favor or aggravate attacks of bronchitis or
asthma in those living in the vicinity of gas-works, chem-
ical factories, etc., but too little comes from ordinary
chimneys to do much, if any, harm.
In-doors the case is different, for the gases from lights
and fires become more and more concentrated as the ven-
tilation is insufficient. The possible effects of varying
percentages of carbonic acid have been noted. We have
no evidence of cases of chronic poisoning by this gas,
although, as Parkes says : " The presence of a very large
amount of CO2 in the air may lessen its elimination from
the lungs, and thus retain the gas in the blood, and thus in
time possibly produce serious alterations in nutrition/'
In cases of acute poisoning by this gas — i. e., where it
is in great excess in the atmosphere — there is an almost
immediate loss of muscular power, and the person may be
unable to remove himself from the place of danger, while
others who go to help him may also succumb and more
than one be asphyxiated. Consequently, volunteer res-
cuers should remember to act with coolness and great
rapidity, and always to provide means for the prompt
removal not only of the one they would save, but of them-
selves. Fortunately, when one who has been overcome
by carbonic acid is brought into an atmosphere of pure
air before life is extinct and is aided by artificial respira-
tion, he usually recovers rapidly and completely.
Cases of poisoning by carbon monoxide are much more
serious. Recovery from its effects is slow and uncertain,
because this gas unites with the haemoglobin of the red
blood-corpuscles, paralyzing them, as it were, and render-
ing them unable longer to act as oxygen carriers to the
THE ATMOSPHERE— AIR. 85
tissues; while the union of carbon dioxide with the blood
is always an unstable one and readily broken as soon as
an interchange with a normal atmosphere is available.
Less than one-half per cent, of carbon monoxide in the
air has caused symptoms of poisoning, and more than one
or two per cent, is quickly fatal to animals. " It appears
that the gas, volume for volume, completely replaces the
oxygen in the blood, and cannot again be displaced by
oxygen, so that the person Hies asphyxiated; but Pokrow-
sky has shown that it may be gradually converted into
carbonic dioxide and be got rid of."
The symptoms of carbonic oxide (monoxide) poisoning
are feebleness, oppressed breathing, trembling, and ina-
bility to swallow; then " loss of consciousness, destruc-
tion of reflex action, and finally paralysis of the heart."
" Hirt says that at high temperatures (25° to 32° C.=
77° to 90° F.) it produces convulsions, but not at low
temperatures (8° to 12° C.=46° to 54° F.)." The blood
and muscles are made a brilliant red by this gas, dark-
ened by carbon dioxide. Claude Bernard says that a
mixture of these two gases is more destructive than either
separately, probably because it interferes with the conver-
sion of the monoxide to the dioxide in the blood, as was
shown by Pokrowski.
Illuminating or coal-gas — composed of hydrogen, light
and heavy carburetted hydrogens, a little nitrogen, and
carbonic acid, and from 5 to 7 per cent., or even more, of
the carbon monoxide — rapidly causes, when inhaled, gid-
diness, headache, nausea and vdmiting (?), confusion of
intellect, loss of consciousness, general weakness and de-
pression, partial paralysis, convulsions, and the usual
symptoms of asphyxia. Mixed in large proportions with
the air, death may ensue comparatively quickly, probably
86 ^ MANUAL OF HYGIENE AND SANITATION.
because of the large content of carbon monoxide; and it
is well to remember that the so-called water-gas, now so
extensively manufactured for fuel purposes and also for
diluting coal-gas, contains a much larger percentage of
carbon monoxide (sometimes from 30 to 40 per cent.)
than the latter, and that the symptoms resulting from its
inhalation will be in all likelihood more marked, more
rapid, and more deadly than with the undiluted coal-gas.
" The effects of constantly inhaling the products of gas
combustion may be seen in the case of workmen whose
shops are dark, and who are compelled to burn gas during
a large part of the day; the pallor, or even anaemia and
general want of tone, which such men show, is owing to
the constant inhalation of an atmosphere so impure."
Sulphurous acid gas (SO2) and sulphuretted hydrogen
(HaS) are each fatal to life, the latter when in a compara-
tively concentrated state; but they are offensive and irrita-
ting to the senses, and thus give warning of their presence,
so that there is less danger of their causing serious results.
Men can accustom themselves to much larger proportions
of sulphuretted hydrogen in the atmosphere than can
animals, but continued exposure to it is liable to give rise
to vertigo, headaches, slow and weak pulse, sweatings, and
loss of strength.
When sewer-gas or soil-air escape into the outer air
they are usually soon diluted beyond any power for harm;
but if either gains access to closed rooms or unventilated
dwellings, its effects upon the inmates is depressing and
decidedly bad. In either case, concentration of the im-
purities may cause acute symptoms, such as vomiting,
purging, severe headache and prostration, and either
soil-air or sewer-gas may at any time carry the germs of
infectious diseases. Their influence, however, is usually
THE ATMOSPHERE— AIR. 87
insidious, owing to dilution with the house-air, and the
more common symptoms will probably be pallor, languor,
frequent headaches, loss of appetite, diarrhoea, impaired
health, and often chronic anaemia. Children especially
suffer in nutrition, and with them febrile attacks may be
frequent; but with all the power of resisting such diseases
as typhoid fever, diphtheria, etc., is lessened and the sus-
ceptibility to them increased, the sickness more severe, and
the convalescence more prolonged. Indeed, sewer-gas and
soil-air probably aggravate all diseases.
In this connection Alessi has shown that when small
animals, such as rabbits, rats, and guinea-pigs, have been
exposed to sewer-air for some days, by far the larger
majority when inoculated with only a small quantity of a
slightly virulent typhoid culture contract the disease and
die, while almost none of those treated similarly in every
way excepting by the exposure to sewer-air, succumb. He
also showed that the inoculations were more deadly when
the previous exposure to the noxious gas had been less
than two weeks than when it exceeded that period, indi-
cating that persons accustomed to such contamination are
not apt to manifest the symptoms due to it so rapidly or
so seriously as are those who experience it for the first
time, a fact well known to all observers.
" There is undoubtedly a poisonous agency at work
when sewer-gas is inhaled, which, though it may not
directly act, yet so prepares the soil that the system is
unable to resist the invading organism when it comes."
1 Notter and Firth, p. 159.
CHAPTER IV.
VENTILATION AND HEATING.
As we are not usually able practically to destroy the
impurities of the atmosphere as fast as they are produced,
we have recourse to ventilation as a means for their dilu-
tion and prompt removal. We must not think, however,
that we do all that is necessary if we only renew the air
within our dwellings, for unless the source aud supply
from which we take that which is to replace or dilute the
vitiated air be pure and clean, any system of ventilation
which we may adopt will be of little value.
External ventilation of our buildings, streets, and cities
is of importance, then, as well as that which relates only
to the interior of our dwellings, workshops, aud places of
assembly. Numerous investigations and statistics, both
here and abroad, show that " the health of a town largely
depends upon the width of the streets, the general height
of the buildings, and the amount of yard space at the rear
of each which separates it from its opposite neighbor/7
It is also hard to overestimate the value of wide streets,
numerous diagonal ones, and frequent parks or open spaces,
especially in the most thickly inhabited portions of a city.
In this connection I may refer with advantage to some
work of Dr. H. S. Anders, of Philadelphia, in which he
shows that " the number of deaths from phthisis on a very
wide street is proportionately small compared with those on
almost any one narrow street/7 and " that there is plainly
and generally a high mortality rate from consumption
VENTILATION AND HEATING. 89
associated with street narrowness in not a small part of
Philadelphia, and that the relation between a high mor-
tality and narrow streets is a positive and vital one."
His statistics, covering a period of fifteen years, show that
in one city ward, certainly favored as to location, the ratio
of deaths from phthisis per square or block on streets over
to those on streets under forty feet in width, was approxi-
mately as 3 is to 5.
As regards internal ventilation, it will be well to deter-
mine at the outset the meaning and limitations of the term.
Parkes says: "It will be desirable to restrict the term
ventilation to the removal or dilution, by a supply of pure
air, of the pulmonary and cutaneous exhalations of men,
and of the products of combustion of lights in ordinary
dwellings, to which must be added, in hospitals, the addi-
tional effluvia which proceed from the persons and dis-
charges of the sick. All other causes of impurity of air
ought to be excluded by cleanliness, proper removal of
solid or liquid excreta, and attention to the conditions sur-
rounding dwellings." With the function of ventilation
thus limited, it will not be necessary to make provision
for such an abundant supply of pure air as might other-
wise seem advisable. It is evident, also, that the purity
of in-door air must almost always be relative and not
absolute, especially in a climate like ours, which, for a con-
siderable portion of the year, necessitates the warming of
the air and some consequent economy in its use.
It seems strange that more attention has not been given
to the possibility of purifying a vitiated atmosphere by
means of fire rather than by the removal or dilution of
the impurities, especially as we so often employ heat as an
agent to destroy or alter the harmful qualities of other
substances intimately concerned with our welfare. The
90 ^ MANUAL OF HYGIENE AND SANITATION.
objection that many would offer at first thought to such a
plan is that the fire would rob the air of all or most of
its oxygen, but a little calculation and consideration will
show that this is by no means a necessary result, and that
a proper apparatus might actually require but compara-
tively little of this gas and give off but little carbonic acid
as a combustion product to the atmosphere. So far as the
writer knows, but one device on the market has this func-
tion professedly embodied in it, and it apparently does
what is claimed for it in this respect. The possibilities of
the suggestion invite further investigation.
To discover the quantity of air desirable and consistent
with the requirements of good ventilation and the non-
interference with health, two factors must be determined :
(a) The extent to which the air of a room is contaminated
in a given time by the impurities it receives, and (6) the
limit of permissible impurity beyond which there will be
a possible risk or detriment to health. In accordance
with the above limitations of Parkes, the contaminating
substances will usually be comparatively few in number,
but the same rules are to be applied in the case of any
detrimental substances in the atmosphere at any time, pro-
vided their source or cause cannot be directly removed.
Although it is extremely difficult to determine quanti-
tatively the organic matter given off by human exhalation
in any given time, the carbonic acid, as has already been
stated, is usually given off in a reasonably constant ratio
with it, and can, therefore, be used as an index of the
amount contaminating the air. Taking Pettenkoffer's
figures, viz. , 0. 6 cubic feet of carbonic acid per hour per
head for a mixed assemblage at rest, 0.7 cubic feet for
adult males, and increasing amounts according to the
physical work done, which have been substantially con-
VENTILATION AND HEATING. 91
firmed by other investigators, we have the first factor (a)
of our problem determined for all cases where the products
of respiration are the only contaminants.
In establishing the limit of permissible impurity — the
second factor (b) — it will naturally be advisable to require
that the supply of air from without shall be sufficient not
only to be thoroughly consistent with health, but that there
may be no perception of impurity by the senses, the air of
the room remaining apparently as fresh and pure as that
out of doors. To this end Dr. de Chaumont made a large
number of observations (over 450), and found that as long
as the carbonic acid due solely to respiratory impurity did
not exceed 0.02 per cent., the in-door air did not differ
sensibly from that without, but that when the respiratory
CO2 reached 0.04 per cent., the air was rather " close/7
and the organic matter was becoming perceptible to the
sense of smell. Subsequent investigations have shown
that as long as the respiratory CO2 does not exceed 0.02
per cent, it has no perceptible effect upon the health ;
consequently, we may take this amount of carbonic acid
over and above the amount normally present at the time
in the outer atmosphere as our limit of permissible im-
purity in inhabited apartments.
Having now the two factors of our problem, it becomes
a simple matter of proportion to determine the amount
of fresh air to be supplied to each individual, provided
there are no other sources of contamination. The equiva-
lent of 0 02 per cent, is 0.0002 of a cubic foot of carbon
dioxide in each cubic foot of air. In a mixed assembly
each person exhales 0.6 cubic foot of carbon dioxide per
hour. Consequently, to dilute this respiratory CO2 prop-
o f{
erly, each person will need — - — or 3000 cubic feet of
/J 0.0002
92 A MANUAL OF HYGIENE AND SANITATION.
fresh air per hour. If the individuals are all adult males,
or if they are working, there must be a corresponding
increase in the air supplied, running up to 6000 or even
9000 cubic feet or more per head in certain laborious occu-
pations. This is the theoretical amount necessary for good
ventilation, but in practice we find that we can get along
with safety and comfort with somewhat less fresh air, be-
cause some of the bodily impurities are at once carried away
and out of the room by the draughts through the exits, or
through cracks and crevices in the walls and ceiling which
act as exits, and the incoming air does not, therefore, have
to mix with and dilute that portion of the impurities that
is so immediately removed. In other words, if 10 per cent,
of the vitiation is thus directly removed, 10 per cent, less
of pure air is needed to dilute the remaining contaminants
to the limit of permissible impurity; but as the quantity
and the consequent velocity of the incoming or of the out-
going air diminishes, less and less of the impurities are
thus directly removed, and experience teaches that almost
the full theoretical amount of fresh air is needed in prac-
tice to secure satisfactory results.
Provision must also be made for sufficiently diluting
the impurities from other sources of vitiation whenever
they are present. Although combustion products are not
usually as dangerous as impurities^ from the human body,
and though they are generally massed near the top of the
room, we should provide at least 1800 cubic feet of air for
each cubic foot of gas burned, and ten times as much for
each pound of oil consumed.
In sick-rooms and hospitals an exception must also be
taken to the equation in which 0.02 per cent, of carbonic
acid is taken as the permissible respiratory impurity, for
it is found that the organic matter exhaled from the sick
VENTILATION AND HEATING. 93
is much more offensive than that from the healthy, and is
noticeable to the senses when the respiratory CO2 is much
below 0.02 per cent. So, one-fourth or more of fresh air
at least must be added to the usual amount to be supplied
to the healthy, and the rule is to give the sick as much
as possible, provided it be properly warmed and dis-
tributed.
The use of the following formula will often be advisable
in solving problems relating to ventilation, viz. : - = d,
where e represents the amount of carbonic acid exhaled in
the given time, r the respiratory CO2 in parts per cubic foot,
and d the delivery or volume of fresh air in cubic feet. Ex-
ample: What will be the respiratory impurity in the air of
a room of 3000 cubic feet capacity which has been occupied
by three men for two hours, supposing that there has been
an ingress of 9000 cubic feet of fresh air in that time ?
Here e = 0.7 X 3 X 2 = 4.2, and d = 3000 + 9000 =
12,000. ^ = 12,000 : = r = 0.00035 = 0.035
per cent. CO2.
Before considering the means by which a sufficient quan-
tity of pure air may be supplied to buildings and apart-
ments, it will be well to note the following restrictions as
to the size and height of the rooms. If a room be too
small, the air therein will have to be changed often, the
velocity at the inlets will be increased, uncomfortable
draughts will be created, and the air will not diffuse itself
so thoroughly throughout the room. Experience shows
that even when the air is properly warmed it cannot be
changed much oftener than three times an hour without
discomfort to the occupants of the room, unless the venti-
lating apparatus be very perfect in its workings, and,
94 A MANUAL OF HYGIENE AND SANITATION.
therefore, expensive. Consequently, as we take 3000
cubic feet of fresh air to be the average amount required
per person per hour, the cubic space per individual should
be at least 1000 cubic feet, with a corresponding increase
where the occupants are all adult males, are all at work,
or are in hospitals.
Again, it must be remembered that the difficulty of
securing equable heating and ventilation increases with
the height of the room above a certain limit, and that
with the sick especially a certain amount of floor-space is
necessary, both for the separation of patients and conven-
ience of attendance. Ten or twelve feet will usually be
found to be the safe limit of height for all apartments
intended for continuous rather than temporary occupation,
and, consequently, there should be a minimum allowance
of from 85 to 100 or more square feet of floor-space
per head, and an increase even upon this in workshops,
hospitals, etc. However, there is no objection to high
ceilings if you are not limited as to floor-space, pure air
supply, and heat; and they may even be advisable in
rooms where many lights are to be burned. Again, these
restrictions regarding cubic and floor-space do not neces-
sarily apply to such buildings as churches, theatres, etc.,
which are occupied for only a comparatively limited time,
which can be thoroughly flushed out after use, and in
which it is evidently impracticable to allot to each person
the above floor area. Yet pains must be taken in such
assemblies to keep the atmosphere pure by whatever means
are necessary; while for school-rooms and the like there
must be extreme care that the pupils are not overcrowded,
and that they have a full supply of properly warmed air.
Any correct system of ventilation, in addition to the
above considerations, must take into account the source of
VENTILATION AND HEATING. 95
the air supplied, the distribution, and the heating or cool-
ing of the air when necessary.
The air supplied to any house should be taken from
well above the level of the ground, where it is free from
contamination and is constantly changing, and not from
cellars or closed areas, where the atmosphere is stagnant
and full of impurities. The conduits leading to the heat-
ing or ventilating apparatus should also be so arranged
that they may be frequently and readily cleaned; it is well
to have them covered with gratings to prevent objects
being thrust into them, and, in extreme cases, it may even
be advisable to filter the air through coarse cloth or fine
wire gauze to free it from dust and other impurities. In the
mechanical system of ventilation adopted in the chemical
laboratory of University College, Dundee, the air is filtered
by being passed through jute cloth (light Hessian) stretched
on frames seventeen feet long by four feet wide. In this
case the presence of the screen actually increased the de-
livery of the air by nearly 10 per cent., probably by pre-
venting eddies. The screens collected two and one-half
pounds of dirt in seven weeks. They last about a year,
and the cost is about 2d (four cents) a yard.1
The air may be kept in motion and efficient ventilation
produced (1) by those forces continually acting in nature,
producing natural ventilation, and (2) by these in combina-
tion with other forces set in action by man, giving artificial
ventilation. The three main forces of natural ventilation
are diffusion, the winds, and the difference in weight of
volumes of air of different temperatures.
Diffusion is constantly taking place between all the gas-
eous constituents and impurities of the air, and even goes
1 Stevenson and Murphy, vol. i. p. 51.
96 A MANUAL OF HYGIENE AND SANITATION.
on through brick and stone walls, but is insufficient in
itself to keep the air pure, though it does much to further
this. Moreover, as suspended matters are solid, not gas-
eous, they are not changed or removed by it.
However, the action of this force should not be ignored
in our calculations as being insignificant, for it is not
only continuous, but it affects the whole volume of the
atmosphere in maintaining its uniformity of composition.
u Roscoe found that when he evolved carbon dioxide in a
room the amount had decreased one-half from that cause
(diffusion) in ninety minutes."1 The rate of diffusion is
inversely as the square roots of the densities of the gases
concerned.
Winds are powerful agents for ventilation, and a slight
breeze passing through a room changes the air therein
many times in the course of an hour, and carries out by
its force many of the solid impurities not affected by diffu-
sion. Winds will pass through walls of wood, brick, or
stone, although their progress is markedly arrested by
much moisture in the walls and by paper or plaster.
The average rate of movement of the wind is consider-
able, but the difficulties in the way of applying them in
ventilation are the uncertainty of their direction and
velocity, the difficulty of regulating them, and the fact
that they may fail us at a time when we need their action
most. In winter they usually have to be excluded directly
from our houses, because a velocity of five or six feet
per second is not to be borne unless the air be pre-
viously warmed. We may, however, take advantage of
the fact that a small current with a high velocity will set
in motion a large volume of air, and that wind blowing
i Notter and Firth, p. 194.
VENTILATION AND HEATING.
97
across the top of a tube will cause an upward movement
of air in the tube. This is one reason why there is often
a draught up an unusued chimney and why it acts as a
good ventilating outlet. To utilize these perflating and as-
pirating powers of the wind, and to prevent back draughts
down chimneys and ventilating pipes, we make use of cowk,
either movable or fixed. We can so arrange these that
FIG. 13.
Cowl or ventilator' for aspiration.
the force of the wind either drives air into the house (per-
flation), or draws air out of it (aspiration). ' Very good
systems employing these have been put in operation, the
air being warmed, if necessary, by passing it over stoves,
steam coils, etc., and they are especially useful where the
7
98 A MANUAL OF HYGIENE AND SANITATION.
inner air is colder than that externally, and where arti-
ficial methods of ventilation dependent upon heat cannot
be employed, as in the holds of ships, deep basements,
etc.
The most important agent in natural ventilation is, how-
ever, the movement produced by variations in the specific
gravity of air. Though the wind might be included under
this head, being produced by the same force, the latter
acts independently of the wind, especially in closed build-
ings. As the air expands when heated, equal volumes be-
come lighter than they were hitherto and rise, and colder,
heavier air pushes in beneath to occupy the space. But
in all inhabited apartments a warming of the atmosphere
is continually taking place, not only by the lights and
fires, but also by the bodies of the occupants. The
movement is, therefore, a continual, though not neces-
sarily an equable one, varying as it does with the tem-
perature of the out-door air and the number and inten-
sity of the heating agents within. There being such a
heating and movement of the air, it follows that, unless a
room be perfectly air-tight, some of the apertures will act
as inlets and others as outlets, and the quantity flowing
out of the room will be practically equivalent to that flow-
ing into it. Therefore, though this force may not be as
powerful or efficient as strong winds at certain times, yet
being more constant, more readily calculated, and more
controllable, it is the one most to be considered in arrang-
ing a system of ventilation.
To determine the velocity of this influx or outgo of air,
we make use of the law that a fluid passes througli an open-
ing in a partition between two volumes of the fluid with
the velocity which a body would acquire in falling through
a height equal to the difference in level of the fluid on the
VENTILATION AND HEATING. 99
two sides of the partition. In the case of a current of
air we substitute for the difference of level the difference
in pressure on the two sides of the partition or opening,
•and this is expressed by the difference in temperature
multiplied by the difference in height of the openings of
entrance and exit, and divided by 491, T^T representing
the expansion of the atmosphere in volume and lessening
of density for each degree (Fahrenheit) of rise in temper-
ature. The velocity will, therefore, equal
/
^
(diff. in temp.) X (diff. in height).
~~
Example: What is the velocity of the current in a chim-
ney 40 feet high, the out-door temperature being 20° F.
and in-doors 70° F.? Answer : V= 8 . /5Q x ^ = 8 X
\ 491
2 +, or about sixteen feet per second.
In actual practice use is made of a table derived from
this formula, or else the velocity is determined directly by
means of the anemometer. Allowance must be made for
the friction of the air against the sides of the ducts and
against itself, amounting to from one-fourth to one-half
of the theoretical delivery, according to the length, size,
straightness, etc., of the inlets and outlets. The friction
will be inversely as the diameter of the openings and
directly as the length of the tubes; the shape of the open-
ings also affect it, and right angles diminish the current
one-half. Accumulations of dust and dirt greatly lessen
the velocity.
The velocity multiplied by the total area of the inlets
or outlets, with a proper allowance for friction, will give
the quantity of air passing through the rooms or series of
rooms in any given time.
One of the most difficult problems in ventilation is to
100
MANUAL GF HYGIENE AND SANITATION.
secure a uniform distribution of pure air through the
rooms, and to remove the impure air as fast as the pure
is supplied, thus preventing its mixing with the latter.
Certain circumstances always make the question compli-
cated: the size and number of inlets and outlets, the rate
and direction of motion, and the forces acting to produce
it must always be subject to constant change, and must
thus constantly alter the result. In fact, it is practically
impossible to devise a plan that will satisfy all conditions
at all times, and the best that can be done will be to select
that one which will give the greatest efficiency and most
satisfactory results under all ordinary circumstances.
FIG. 14.
Anemometer, used for measuring the velocity of air-currents directly, a, slide
for releasing or stopping the dial hands ; e, support for attaching the instrument
to a staff or cane.
The force of diffusion will always act as long as there
is any communication between the exterior and interior,
and no special attention need be given to it. We cannot
use the wind continually, for reasons already given, but
VENTILATION AND HEATING. 101
we should employ it whenever possible by opening doors
and windows, on account of its great power for sweeping
out solid impurities and thoroughly changing the air. In
cold weather, currents from windows, etc., should be
directed toward the ceiling, so that they may be diffused
and partially warmed before reaching the inmates of the
room. Numerous devices have been suggested for intro-
ducing unwarmed out-door air without discomfort, or for
diffusing it through the room: among these may be men-
tioned perforated bricks, or double-paned windows, valves,
screws, etc. A cheap and satisfactory temporary arrange-
ment is to place a board about four inches wide and just
as long as the width of the window-sash beneath the latter.
Or, better, have a light frame covered with fine netting
or wire-gauze, four or five inches wide made to fit above
the upper sash : the fresh air from without can now
enter freely between the upper and lower sash, being re-
flected upward by the inner surface of the glass in the
upper sash, and thus mixing with warm air before reach-
ing the occupants of the room; while the frame at the
top of the window becomes an outlet for the foul air, the
interference of the netting or gauze preventing too rapid
an outgo and consequent loss of heat. But in a climate
such as our own, and in all cold countries, special meas-
ures must be taken during the greater part of the year for
warming the out-door air before introducing it into occu-
pied rooms.
Where we intend to depend most upon the third force
of natural ventilation, viz.,, the movement of unequal
weights of air, we must provide openings for the entrance
and exit of air other than the windows and doors, so that
there will be a practically constant movement through the
rooms in a given direction, that we may be sure the air is
102
MANUAL OF HYGIENE AND SANITATION.
from a pure source, and that we may get the utmost ser-
vice from our appliances.
There is considerable difference of opinion as to the best
locations for inlets and outlets, and as the conditions are
necessarily different in every case, and as so many factors
are to be considered, it is difficult to lay down any general
rules. It should be an aim, however, to have the air well
FIG. 15.
Currents in room lighted by gas and heated by open grate.
distributed throughout the room or rooms, and to have no
direct draughts from the inlets either upon the occupants
or to the outlets. It is the writer's opinion that, usually,
the outlets should be located near the top of the room,
owing to the tendency of the used air to rise, and because,
in unventilated rooms, the foulest air for some time after
its contamination will be found nearest the ceiling. The
products of combustion from lights, etc., will also practi-
VENTILATION AND HEATING.
103
cally all be in the upper strata of air. If, however, pro-
vision is or can be made for a constant and sufficiently
strong aspirating force in the outlet ducts, it will be advis-
able to withdraw the used air near the floor level and
below, though not in too close proximity to, the inlet open-
ings, since in this way a more thorough distribution of the
incoming air and a greater dispersion of its contained heat
are secured. This is aptly shown in the illustration depict-
FIG. 16.
Currents in room heated by a ventilating grate.
ing the currents in a room heated by a ventilating grate.
(Fig. 16.) This principle is also involved in the well-known
Smead system of ventilation and heating, which still
further serves economy by carrying the foul air beneath the
floor of the room from which it is taken, thus warming the
floor with what heat the waste-air yet contains and gaining
the utmost benefit and value from the fuel. (Fig. 17).
The location of the inlets should depend on the tempera-
104 A MANUAL OF HYGIENE AND SANITATION.
ture of the incoming air; if it is cold, it should be admitted
near the ceiling, so that it may diffuse and be practically
warmed before reaching the inmates of the room; if it is
warmed, it may come in near the floor or below the middle
level of the room. Where much fresh air is required, it
is better to have a number of inlets and outlets than one
large one of each, as the distribution is then more certain.
The total area of the outlets may be the same as that of
FIG. 17.
Diagram illustrating the general system of ventilation.
the inlets, as the expansion of the air is scarcely great
enough to require a difference. The outlets should all be
on the same level, else the highest one will be the one of
greatest discharge and often the only one, the others pos-
sibly acting as inlets and drawing air from an impure
source. As the temperature varies from time to time, and
with it the current, some arrangement is needed for regu-
lating the size of the openings of the inlets or outlets to
VENTILA TION AND HE A TING. 105
suit the varying conditions. To supply 3000 cubic feet
of air per head per hour at a velocity of five feet per second
will require an inlet-opening of twenty-four square inches
for each person; but practically it is better to have a larger
opening, as the above velocity is uncomfortable unless the
air be well warmed. Outlet tubes should always be pro-
tected from cold and kept as warm as possible.
Artificial ventilation is that which is brought about by the
intentional application of the above mentioned and other
forces, and by means of special apparatus and devices, in
contradistinction to natural ventilation, which may act in-
dependently of human cognizance and intention. It may
consist in either extracting air from or forcing air into a
room or building, or in both together. In the first method
the object may be attained by heating the air in the outlet or
the outlet itself, or by the use of a fan, a screw, or a steam or
water-jet. Of the first of these the common house-chimney
is as good an example as any. As long as there is a fire in
a grate or stove connected with the chimney there will
be a constant upward current; and the area of the chim-
ney's cross section being known, and the velocity deter-
mined, as already indicated, by the anemometer or by calcu-
lation, the amount of air passing out of the room in this
way may readily be determined. In this connection it
may be stated that a chimney may thus act as the only
outlet, and all other openings into the room serve as inlets,
especially when the fire is strong, and that the upward
current will be practically equivalent to the amount of
incoming air. Moreover, the outgoing current may be so
strong as to overtax the capacity of the inlets, in which
case more or less of a vacuum will be formed in the room
and down draughts will probably be set up in the chimney ?
and smoke carried back into the room. The remedy is to
106 A MANUAL OF HYGIENE AND SANITATION.
enlarge the inlet area by opening a door or window, or to
lessen the draught by means of a damper in the chimney.
On the other hand, the inlets may be so large and the
current so strong that the air in the room cannot be prop-
erly warmed, in which case the size of the outlet should
be lessened by a damper, or there should be an increase in
the efficiency of the heating apparatus.
When we wish to draw air from distant and non-com-
municating rooms, the ducts may be led into a chimney
below or just above a fire, or, better, into a flue or shaft
alongside or encircling the heated chimney. The draught
is greater just above a fire than below it, but conduits
should not enter near the top of a chimney, for there the
extracting power is not so great and there is danger of high
winds blowing smoke and foul air back into the rooms.
Outlet flues should be alongside chimneys that are being
constantly used; should be as smooth as possible interi-
orly, and should be as high as the adjoining chimney to
avoid down draughts. The openings from the rooms into
these ducts should be as near the ceiling as possible, to get
the benefit of the high temperature of the upper strata of
air, unless, as previously indicated, there is certainty of the
extracting force being constant and sufficiently strong,
when the air may be taken from a lower level.
In hospitals and other places where a constant and inde-
pendent supply of heat can be afforded, extraction shafts
apart from chimneys may be used. These extraction shafts
may be heated by fires, steam pipes, or steam jets at the
bottom, or by steam or hot-water pipes coiled around the
sides. Some system like this is used in mines, where large
quantities of air must be extracted. There is an entrance
and an extraction shaft; large fires are constantly main-
tained at the bottom of the latter, the air is drawn down the
VENTILATION AND HEATING.
107
former, diverted through all parts of the mine by partitions,
and finally heated and carried up the extraction shaft.
\Ve may also use a jet of steam or water in place of heat
to extract air through a shaft, the openings of the foul-air
ducts being back of or behind the jet. It is said that a
steam jet may thus set in motion over two hundred times its
FIG. 18.
Air propeller, with electric motor attached.
own bulk of air. Lastly, fans driven by steam or water-
power have been employed to extract the air, though these
are usually more efficient in forcing in air. For instance,
one of 36 inches diameter, at 600 revolutions per minute
will extract over 18,000 cubic feet of air per minute.
In ventilation by propulsion or forcing in air, these
108 A MANUAL OF HYGIENE AND SANITATION.
large revolving fans are generally used. The advantages
of this system of ventilating are the certainty as to the
direction of current and amount of air supplied, and the
ease with which the quantity can be altered or measured.
The disadvantages are the high cost of power in most
cases, the inconvenience or danger from prolonged stop-
page from accidents to the apparatus, and some difficulty
in distributing the air. For instance, if it be forced in
through small openings or at too great a velocity it will
not mix properly with the air of the room . The increased
use of electric motors and lowered cost of running them
will doubtless serve to make this system of ventilation
more common in the near future.
House Warming-. In cold countries there must be
some resort to artificial heat in the winter season, and as
this subject is more or less inseparably and closely con-
nected with ventilation, it may be appropriately consid-.
ered at this time. Cold is depressing, uncomfortable, and
dangerous to the young and aged, and to women whose
habits of life keep them much indoors; though well-fed,
healthy, adult men may not be much affected, if accus-
tomed to it. In this country we need a higher tempera-
ture in our houses than in Great Britain, on account of
our drier climate; evaporation and consequent cooling of
the body take place more rapidly here, and so, while they
are accustomed to a temperature from 60° to 65° F., we
find from 65° to 75° F. to be no more than comfortable.
It needs but slight investigation to determine that we
practically make use of but two kinds of heat — radiant
and convected — in the heating of houses, and that of these
the latter is by far the most generally employed and the
most economical. Radiant heat, although it is the most
healthful and warms an object directly without raising the
VENTILA TION AND HE A TING. 109
temperature of the intervening air, has the disadvantages
of utilizing but a small proportion of the fuel value, of
decreasing directly as the square of the distance of the
object from the source of heat, and of being available only
in comparatively small apartments. Our best example
of radiant heat is that which conies from open fires, though
any highly-heated object, as a stove, gives off more or less
of it. Heat that is carried from one place to another by
heated masses of air, water, or steam, is said to be con-
vected, and because of the economy in its use and the ease
of distribution, especially in large spaces, it is the kind
most generally used. Conducted heat, which passes from
molecule to molecule of the conducting substance, acts too
slowly to be available to any extent in house-heating, and
may, therefore, be omitted from this discussion.
Just here it may be remarked that, under present condi-
tions, there are three things, any two of which we may have,
but not all three together, except in rare instances : they
are good ventilation, efficient heating, and cheapness.
The reason for this is that any good system of ventilation
necessarily and continually carries off a large quantity of
air with its contained heat, which latter is lost for heating
purposes and must be replaced at the expense of more fuel.
A heat unit cannot be used at the same lime to produce
ventilation and to heat objects other than the air it keeps
in motion. The principal aim, then, in establishing any
system of combined ventilation and heating must be to
heat, introduce, and carry off no more air than is necessary
for the requirements of good ventilation and health, and
to produce the heat for warming this air and the house
itself as economically as possible; though care must also
be had to secure- evenness of distribution, absence of
draughts, etc.
HO A MANUAL OF HYGIENE AND SANITATION.
The usual appliances for house-heating are open grates
or fireplaces, stoves, and hot-air, steam, and hot- water fur-
naces. To these may now be added electrical heaters, but
the cost of maintaining them at present prevents their use
by any but the wealthy.
Ordinary grates and open fireplaces give practically only
radiant heat, and render available only from 7 per cent, to
12 per cent, of the fuel efficiency. They also only heat
directly the surfaces of objects facing them, leaving the
remainder cold; and by reason of the great current up the
chimney are also apt to bring in large quantities of air from
without that has not been properly warmed, and to thus
cause injurious draughts. Where there is some additional
means of heating the air before it enters the apartment,
and where the chimney current is controlled by a damper,
they are valuable, not only for the good ventilation they
produce, but for the pleasing effect of the exposed fire.
To make open grates most effective for heating, the sides
and top should be inclined to the back at an angle of 135°,
so as to throw as many heat-rays as possible into the room;
the fuel surface should be concentrated, and there should
be a damper to prevent too rapid combustion and too
much heat and air escaping up the chimney. It is to be
understood, of course, that the objects warmed by the
radiant heat of the open fire do in turn give us convected
heat by warming the air surrounding them.
If, however, the back and sides of these grates be sur-
rounded by a space through which the air can pass and be
warmed by the heat that would be otherwise wasted, we
shall have a much better heating apparatus, since we thus
get both radiant and convected heat, and may obtain from
25 per cent, to 35 per cent, of our fuel efficiency. And
if outdoor-air be let into this air-space and warmed, the
VENTILATION AND HEATING. HI
ventilation will be greatly improved, other inlets will be
unnecessary, uncomfortable draughts will be avoided, and
there will be enough heat provided for one or more apart-
ments of moderate size. The air-chamber at the back
should not be too small, and there should be as much
heated surface to warm the incoming air as possible.
FIG. 19.
Jackson's ventilating grate. The outer casing is cut away to show space and
surface for warming the incoming air.
Stoves utilize a considerable percentage of the fuel —
75 to 80 per cent, or more — but do not remove much air ;
so ventilation has to be provided for in some other way
and is apt to be neglected. Stoves may also give off dan-
gerous gases and products of combustion if not properly
cared for, or if the damper in the stovepipe be entirely
closed. There should be as much surface exposed as is
possible without diminishing the heating capacity, so that
there may be much radiant he,at. It is often advisable,
especially in assembly or school-rooms and the like, to
surround the stove with a sheet-iron cylinder extending
from the floor toward the ceiling, and to bring in between
this and the stove a supply of fresh air from without.
112 A MANUAL OF HYGIENE AND SANITATION.
This air becomes heated and, passing out over the top of
the cylinder or drum, gives a plentiful supply of convected
heat, together with good ventilation. A suitable outlet
must, of course, be provided. Carbon monoxide and other
gases are known to leak through cast-iron when it is too
highly heated, so that stoves should not be allowed to be-
come too hot.
Other objections to stoves that are allowed to become
too hot are the excessive dryness of the atmosphere which
they cause, and the unpleasant odor due to the scorching
of floating organic substances that come in contact with
the hot iron.
The fuel most commonly used in both grates and stoves
is either wood or some kind of coal (bituminous, anthra-
cite, or cannel); but gas may often be advantageously em-
ployed instead of any of these, since the heat can be had
from it practically instantaneously, can be closely regu-
lated in quantity, and can be promptly checked when no
longer desired, and since there is no production of dust or
ashes in the room. The main objection to gas is that for
large rooms or prolonged or continuous heating it is
usually more expensive than the other fuels; but this does
not hold good for small rooms, and sometimes for isolated
apartments, or where the warmth is needed only tempora-
rily; and it is very probable that before long fuel gas will
be — it can be now — supplied at rates which will justify a
much more extended use of such fuel.
The ordinary kinds of gas-grates and stoves, especially
those which consume the gas incompletely, should all be
constructed with flues to carry off the products of com-
bustion directly, and this particularly when any large
quantity of gas is used. Theoretically, when the gas is
burned in a properly adjusted Bunsen or " atmospheric"
VENTILATION AND HEATING.
113
burner, the only combustion products will be carbonic acid
and water, the former of which is rapidly diffused into
the outer air, as has been shown, and is not likely to be
harmful in any quantities thus produced, while the aque-
ous vapor is beneficial to the atmosphere rather than other-
wise. However, it seems that in practice even these Bunsen
burners may sometimes give to the air a disagreeable odor
(said to be due to the formation of acetylene), and so need
flue connections.
FIG. 20.
Section of Backus' portable steam radiator for use with gas.
In this connection it may be interesting to describe one
form of gas-heater which, so far as the writer knows, is
unique. It is intended not only to consume perfectly the
gas it uses, giving nothing to the air but carbonic acid
and water, but also to destroy by fire the impurities of the
atmosphere of the room, thus doing away with chimneys
8
114 A MANUAL OF HYGIENE AND SANITATION.
or flues and the necessity of much ventilation. By a
peculiar arrangement, a continued current of air is made
to pass through the flame, thus burning the impurities,
whether gaseous or solid. The heat of the burning gas is
also used to convert a quantity of water into steam, thus
warming the containing chamber or coils of pipe, and these
in turn the air surrounding them, in this way warming
many times the volume of air possible to heat by the flame
alone. In addition, the normal humidity is maintained
in the atmosphere by the evaporation of water from an
open basin beneath the fire.
The ordinary openings of any room are amply sufficient
to allow the diffusion of the excess of carbonic acid — one-
half escaping in this way, according to Roscoe, within
ninety minutes — and to permit the ingress of enough air
fully to supply all the needs of the inmates and of the fire
itself. Experience and careful experiments seem to show
that the claims of the inventor are well founded and that
the apparatus is healthful in its operation and produces
no harmful effects, even after continued use for several
months.
At any rate there seems to be no reason why we may
not purify the air by fire instead of by dilution and re-
moval, the methods employed in the hitherto described
systems of ventilation.
Oil-stoves are now used quite extensively and, beside
being portable, have the same advantages as gas-stoves,
viz., that a considerable quantity of heat may be had
quickly and just as long as it is desired, and at a fairly
moderate cost. The combustion products necessarily mix
directly with the atmosphere of the room, and where rea-
sonably perfect burning is had doubtless consist of little
else than carbonic acid and water. One pound of oil, the
VENTILATION AND HE A TING. 1 1 5
hourly consumption of a rather large stove, will require
about 150 cubic feet of air for its complete combustion,
and will produce about twenty-five cubic feet of carbon
dioxide.
" We do not think that the experience has yet been
accumulated which would enable us to speak positively
of the innocuousness of a considerable admixture of car-
bonic acid with the air we breathe, but the knowledge that
in hundreds of cases oil-stoves are used for heating living
rooms and even bedrooms without apparent injury to the
occupants makes one feel fairly confident that the prod-
ucts of the complete combustion of hydrocarbons are not
injurious when mixed with such an amount of air as is
sufficient to dilute to a proper degree the respiratory prod-
ucts. . . . Experiments show that, provided the
combustion of the oil is complete, and that the ventilation
is sufficient for the ordinary effects of respiration, the use
of oil-stoves for heating purposes may be advantageously
employed in both day- and sleeping-rooms. The efficiency
of oil-stoves is increased by placing over them a diffuser
or radiator, so as to prevent the heated products ascending
direct to the ceiling; care needs also to be taken that only
the better kinds of mineral oil are used; if inferior quali-
ties of oil are burnt perfect combustion is more difficult
to obtain."1
The above remarks, as far as they apply to the health-
ful use of the air, may probably be used with equal justice
in regard to gas-stoves, provided that with such dilution,
their products give no obviously harmful or disagreeable
results.
The heating apparatus thus far described is such as we
i Notter and Firth, p. 228.
116 A MANUAL OF HYGIENE AND SANITATION.
are accustomed to employ for warming the air of single or,
possibly, of adjoining rooms. Where a whole dwelling or
other large building is to be heated, it will usually be of
advantage to do this from one point, and that not in any
of the living apartments. In this way we shall have a
centralization of fuel, both unburned and burning, and the
FIG. 21.
Spear's hot-air furnace.
ability to derive more heat from it; a lessening of the labor
and attention bestowed on the fires; the obviation of much
dust, dirt, and combustion-products in living-rooms, and,
presumably, a more equable and satisfactory warming of
the whole building. From such a central point the heat
VENTILA TION AND HE A TING. \ \ 7
is distributed by hot air, hot water, or steam, or by hot air
in combination with either of the other two.
Hot-air furnaces supply a large amount of convected,
but no radiant heat. There is a very prevalent opinion
that they are not healthful and that wherever possible
they should be substituted by some other means of heat-
ing; but when properly constructed and cared for a hot-
air furnace of the proper size is not only a good heater, but
a powerful ventilating agent; for the large supply of air
passing through it into the rooms above must in time find
an exit either through specially devised outlets or through
the innumerable cracks and crevices around all doors and
windows, and the ventilation will be accordingly.
One frequent source of trouble is too small a fire-pot,
giving insufficient heating surface and necessitating too
rapid and too intense combustion of fuel. There should
be a considerable expanse of surface, never too highly
heated, so that large volumes of air will be moderately
warmed, rather than small quantities over-heated and
" burned." Air too highly heated is very dry and offen-
sive to the senses — also, by taking excessive moisture from
the body through the skin and mucous membrane, it
increases the liability to frequent " colds" and conges-
tions. Moreover, a large quantity of air moderately
warmed will, perforce, be carried to all the rooms of the
house, warming them equably and driving before it the
air already there: whereas, a much smaller volume, exces-
sively heated by the same or even a greater amount of
fuel, will make its way along' the channels of least resist-
ance to certain favored rooms, overheating them and
•keeping the rest^of the house cold, beside preventing any
satisfactory natural ventilation.
All joints in the furnace must be as near gas-tight as
118 A MANUAL OF HYGIENE AND SANITATION.
possible, to prevent the combustion products passing from
the fire-box or smoke-flues into the air chambers and
thence into the house.
FIG. 22.
Hot-air furnace, showing cold-air inlet and hot-air flues. Only one of the lateral
branches of the main inlet above is shown.
The furnace should be located near the cold side of the
house — that is, the side on which the prevailing cold winds
impinge, for it is said to be as difficult to drive the air ten
VENTILATION AND HEATING. 1 1 9
feet against the wind as forty or fifty feet with it. It may
also be well, if the basement ceiling is low, to place the
ash-pit even below the level of the basement floor, in order
to give sufficient slope to the air-ducts; but in every case
the space beneath the furnace should be cemented or laid
in asphalt to prevent the drawing in of soil-air.
The air-supply should not be taken from the cellar, even
though the latter be apparently clean and free from any
contamination with soil-air, but should come from a clean
source out of doors, well above the ground-level and from
the direction of the prevailing winds. The cold- air duct or
ducts should be screened at the entrance to prevent the
admission of refuse or vermin, should be arranged to permit
of regular cleaning, should have a damper to regulate the
supply of air, and should have a cross-section of at least
two-thirds of the combined area of the hot-air flues lead-
ing from the furnace. It may be desirable to provide for
the filtration of the air through coarse cloth or fine wire
gause, especially if there be much dust in the incoming
air.
If possible, the hot-air flues or ducts should not be flat,
but round or square, to lessen the friction, and should be as
direct in their course and as nearly vertical as possible for
the same reason. They should be covered from the fur-
nace to the register openings with asbestos or other non-
conducting material, to prevent the loss of heat that
otherwise escapes from them into the cellar and between
the partitions. Lastly, their register-openings into the
rooms should not face the windows or prevailing winds,
unless absolutely unavoidable, for if they do, the passage of
warm air into the room will often be completely checked.
The following table, from Coplin and Be van, will indi-
cate the proper size for hot-air flues and registers :
120 A MANUAL OF HYGIENE AND SANITATION.
FIRST FLOOR.
Size of room in cubic
feet.
Size of pipe.
Size of register.
If round.
If square.
If round. If square.
Less than 1500 .
7 inches
4x9 inches
9 inches 7 x 10 inches
1500 to 2000 .
8 "
4 x 12 "
10 " 8x10 "
2000 to 3000 .
9 "
4x16 " 12 " 8x12 "
3000 to 4000 .
10 "
4 x 18 "
12 " 9x14 "
Economy will be subserved in most cases by taking care
to burn the fuel in hot-air furnaces quite slowly, since in
this way larger quantities of air are warmed and more
satisfactorily, and there is also less waste of heat through
the smoke-flues and up the chimney. Moreover, it is the
experience of the writer, that by working the furnace in
this way at low pressure, so to speak, the air from it will
practically never be too dry, nor need the addition of
moisture, something essentially necessary and yet most
often neglected where too little air is excessively heated.
When it is necessary to carry heat for a considerable
distance or to warm large buildings or blocks of buildings
from a central point, it will be better and more economical
to employ hot water or steam as the heat-transmitting
agent, on account of the high specific heat of the former
and the great amount of latent heat held by the latter.
" It is uneconomical to convey heated air any. long dis-
tance, as the amount of heat conveyed per cubic foot of
air raised to any practical temperature is so small and so
easily lost in transit. On this account Morin considers
the availability (of hot-air furnaces) limited to a horizontal
range of forty or forty-five feet from the heating appa-
ratus."1
1 Stevenson and Murphy, vol. i. p. 117.
VENTILATION AND HEATING. 121
An equal quantity of heat, viz., one thermal unit, is
required to raise one pound of water or fifty cubic feet of
air 1° F., and accordingly water will carry over four
(4.21) times as much heat as an equal weight of air at
the same temperature. " Further, a greater effect is pro-
duced when water, in the form of steam, is made the car-
rier of heat, because one pound of water — vapor — at 100°
C. (212° F.) will, in condensing to form boiling water,
give off sufficient heat to raise the temperature of 5.36
pounds of water (or 4.21 X 5.36 =22.5 pounds of air)
from 0° C. to 100° C. (32° F. to 212° F.)."
Hot-water heating may be by either the low-pressure or
the high-pressure system. In the former large pipes (gene-
rally four inches in diameter) are used, and, the system
being open to the air at its highest point, the temperature
of the water can never be much above 212° F. at any part
of the system. The water circulates comparatively slowly,
but, owing to the large volume, conveys much heat from the
furnace to the places where it is needed. The high-presnre
system employs small but very strong pipes, the water being
completely inclosed from the outer air, wherefore it attains
a high temperature, usually about 300° F., and circulates
rapidly. The necessary expansion is provided for by larger
pipes partly filled with air at the top of the circuit. The
maximum temperature is regulated by the proportion of
pipe exposed to the fire, usually one-tenth. Either of the
hot-water systems, but especially the low, require careful
planning and setting to maintain evenness of circulation;
but when the latter is complicated, as by many radiators at
various levels, or where a number of circulations have to
be supplied from the same boiler, it may be very difficult to
maintain an even head and an equable distribution of heat
in all. " If properly constructed and the heating planned
122 A MANUAL OF HYGIENE AND SANITATION.
for when the house plans are made, this hot-water system
is probably the most economical, both in fuel used and
repairs demanded. "l
Steam-heating methods are usually quite satisfactory,
not only because of the large quantity of heat carried,
but also since a rapid circulation is readily maintained,
even under adverse circumstances. The size of pipe used
will depend on the extent of the distribution, but the
calibre of the radiator should always be considerably larger
than that of the supply pipes, in order to favor conden-
sation and the consequent liberation of latent heat, and
every facility should be provided for the speedy return* of
the condensed vapor to the boiler. Care must also be
taken to prevent the condensation occurring in such a way
as to cause obstruction to the flow of the steam and the
disagreeable thumping and noise that result.
With either steam- or hot-water heating, the direct, the
indirect, or the direct-indirect method of radiation may be
used. Of these the direct method — that is, where the
radiators are placed in the rooms to be warned — is most
commonly employed in dwellings and other buildings of
moderate size; but it is open to the objections that in
itself it does not bring about a sufficient change of air,
that the necessary inlets and outlets for the latter are
rarely provided, and that when present they are indepen-
dent of the heating system of the house. Of course, these
objections are removed when the direct is combined with
the indirect method, or when a plentiful supply of pure
air is brought from without and is warmed by being made
to pass through the radiators (either open or enclosed in
boxing) before diffusing through the room, this being the
1 Coplin and Sevan, p. 325.
VENTILATION AND HEATING.
123
direct-indirect method. In the indirect method the radi-
ators are placed in suitable and convenient enclosures out-
side of the room, into which fresh air is brought from out
of doors and from which the warmed air is conveyed by
suitable ducts to the respective rooms above. If properly
FIG. 23.
Steam radiators and blower used in warming the clinical amphitheatre of the
Medico-Chirurgical College of Philadelphia, by the indirect system. (The casing
of the radiators is not yet applied.) Tempering radiator at left ; warming radiator
at right ; casing of fan between.
arranged, both the indirect and the direct-indirect methods
should furnish good and ample ventilation, the incoming
warm air pushing the used air of the room ahead of it
through the various openings in the walls of the room.
124 ^ MANUAL OF HYGIENE AND SANITATION.
Safety valves on steam boilers prevent any danger from
explosions, and automatic thermo-regulators make it pos-
sible to maintain a practically even temperature through-
out the house or building at all times.
In the Clinical Amphitheatre of the Medico -Chirurgical
College of Philadelphia, the indirect system is employed,
the details being as follows : The cold air is brought from
near the roof-level by a large shaft into the cold-air room,
where it is moistened by a spray and whence it passes
through a dust-filter, consisting of a double layer of fine
wire gauze. Thence it passes through tempering radia-
tor (to modify the temperature) into the revolving fan,
driven by its own engine, whence part passes through a
second and larger radiator to be farther warmed, and part
below the latter, the two currents again uniting and, after
mixing, passing through the flues into the amphitheatre
above. In this the temperature is regulated by a thermo-
stat (which governs a damper not shown in the cut) which
always permits the same volume of air to pass into the
flues, but controls the respective quantities of heated and
tempered air, so that the mixture practically does not vary
in temperature. In this way 900,000 cubic feet of air at
a fixed temperature can be supplied per hour.
For the private operating-rooms the system is the same,
except that the tempered and the heated air are not mixed,
but each is carried by separate flues to double registers in
the operating-rooms. In this way each operator can have
the temperature that he desires in his room at any time.
In very large buildings it may be advisable or necessary,
as above, to drive the air heated by the indirect method
into the rooms (the plenum or propulsion system), or to
withdraw it through special outlets by suction (the exhaust
system). Of these the former is preferable, since the
VENTILATION AND HEATING. 125
source from which the air is taken aijd the inflow through
the heating apparatus are both more certain.
To determine the amount of radiating surface needed
for any room we must multiply the volume of air to be
heated per hour by the difference between its temperature
in degrees Fahrenheit before and after warming, and
divide this product by 50, the quantity of air in cubic feet
raised 1° F. by one thermal unit. This will give the
number of heat units required to warm the air. Then
this quotient must be divided by the difference between
the temperature of the radiating surface and that of the
air when finally warmed multiplied by 1.75, the number
of thermal units given off per hour by one square foot of
hot water or steam-pipe for each Fahrenheit degree of
heat it loses. This will give the area of hot water or
steam-pipe required to warm the given volume of air.
Thus, to warm 6000 cubic feet of air per hour from 20°
to 70° F. will require 6QQO * (70 — 20) = 6000 heat
ou
units, and if the surface of the radiator be 200° F.,
(200° — 70°) X 1.75
of radiating surface needed. To this must be added at
least one-half square foot for each square foot of window
glass and 'for each square yard of outer wall exposed.
CHAPTER V.
WATER.
NEXT to air, water is the most important of all sub-
stances necessary to human life. While it has been often
demonstrated that man may do without food for a consid-
erable length of time, even for several weeks, he can
probably not survive much more than ten days without
water. But not only must we have enough to supply the
internal wants of the body and to replace that lost by
excretion, evaporation, and respiration; but from a sani-
tary point of view, a plentiful supply is needed to maintain
cleanliness of bodies, clothing, and dwellings, and, often-
times, to remove sewage, excreta, etc., from the vicinity of
inhabited places. The care of furnishing water in abun-
dance and of maintaining its purity is, therefore, entirely
within the domain of the physician and the sanitarian.
Before inquiring into the source whence we obtain the
water that we use it will be well to know what amount is
required by the body for its daily needs, and how much
for other necessary purposes, so that we may be able to
judge not only whether a given source furnishes pure
water, but also whether it gives a sufficient supply of it.
The average adult should take from seventy to one
hundred fluidounces per day for nutrition and the internal
needs of the body alone — about one -third of this being a
component part of the food, and the rest being taken in
as drink. The writer is of the opinion that the average
person does not imbibe enough water for the most health-
WATER. 127
ful action of his tissues and organs. Certain it is that in
most cases the plentiful use of a good drinking-water not
only greatly favors the body metabolism, but also materi-
ally assists in the flushing out and carrying away of the
various wastes and excreta of the system.
In addition to this we must supply a sufficiency for
cooking and for washing the food, body, clothing, house-
hold utensils, and parts of the house itself, and to remove
the household waste and sewage through the drains and
sewers provided for that purpose. Cleanliness is an essen-
tial requisite for the preservation of health, and cleanly
habits should be inculcated among all classes of people,
and every facility provided for removing filth of all kinds
from persons, clothes, and dwellings. This, of course,
cannot be done without a fair supply of water.
Experience shows that about twenty-five gallons per
head per day should be furnished for the above purposes,
and as the quantity used by domestic animals, manufactur-
ing establishments, municipal needs, etc., must be added
to this, fifty gallons or even more per capita should be sup-
plied daily, wherever it is at all possible. And though a
supply that permits of excessive waste may be inadvisable
and expensive, both to provide and by increasing the cost
of carrying it away after use, it is always better to have
too much than too little, and the disadvantages of too
scanty an amount are much greater than those of one too
large.
It should be stated, however, that most foreign cities are
supplied with much less water per capita than is appar-
ently needed by the municipalities of this country, and
yet they seem to have an abundance for all necessary pur-
poses and the requirements of public health. For instance,
London, with a population of over five millions, has an
128 A MANUAL OF HYGIENE AND SANITATION.
average daily supply that but slightly, if at all, exceeds
that of Philadelphia, with one-fourth the number of citi-
zens; while Berlin, which is of about the same size as
Philadelphia, had in 1893 an average daily supply of
filtered water of only 18.4 gallons per head, all of which
was sold to the consumers by meter, but to which must be
added considerably more that was from wells and was
exclusively used for manufacturing purposes, running
machinery, etc. It cannot be doubted that the quantity
wasted in many of the cities in this country is excessive,
and that the cost of supplying that part of the total quota
would go a long way toward improving and rendering
pure and safe the remaining part that is absolutely needed.
Whether the compulsory use of water meters is the best
way of bringing about an improvement in this respect
remains to be determined; but it is also a question whether
our larger cities, with rapidly increasing populations, can
afford to use the means necessary to safely purify the
enormous quantity of water now daily supplied to their
respective consumers.
As only a small portion of the quantity indicated above
is required for the internal needs of the body, it has been
suggested that two kinds of water be furnished — one for
drinking and cooking purposes and for the washing of the
body, to which especial attention as to purity should be
given; and another kind for all other purposes, its~com-
position and purity being disregarded, excepting possibly
as concerns the hardness. This would enable the authori-
ties to furnish a water purer than usual for those needs
where purity is of the greatest importance, and would
obviate the need of furnishing pure water abundantly for
all purposes; but the scheme would necessitate a double
set of reservoirs, mains, distributing apparatus, etc. , thus
WATEE. 129
materially increasing the cost; and there would always be
present the danger of the careless or ignorant using the
impure water for bodily needs, thus increasing the risks
and bad results that we wish to avoid. Therefore,
wherever there can be an abundance of pure water for all
personal and domestic purposes, if the authorities but take
pains to furnish it, it will be best to have but one supply
in dwellings, and this as pure and abundant as money and
the highest sanitary skill can make it; though there may
be little or no objection to using a different water for
factories, stables, city uses, etc.
As to the question of supply through meters, it may be
added that the suggestion has been made that the regular
charge for water begin only after a certain specified amount
per month per capita or per household has been furnished
free or at the lowest possible cost, thus d<5ing away with the
objection that those who need the water most for personal
and sanitary uses would be tempted to economize too
much if they had to pay for all they consumed. Whether
a city could afford to do this would have to be carefully
considered, and would probably depend largely upon local
circumstances.
Sources. Practically, all drinking-water has at some
time or other fallen upon the earth from the air in the
form of rain, hail, snow, or dew; but when we speak of
its sources we have reference rather to the place or locality
from which we collect it for use. The rain on reaching the
earth is disposed of in three ways : part at once evaporates
and goes back to the atmosphere, part flows off according
to the slope of the ground and collects in pools and streams,
and part sinks into the soil. The ratio which these three
portions will bear to one another will depend on the time,
place, character of soil, intensity of rainfall, etc. Conse-
130 A MANUAL OF HYGIENE AND SANITATION.
quently, we may classify the sources of potable waters —
as Leffmann does — as follows : Rain-water, collected im-
mediately as it falls from the atmosphere, in the form of
rain, dew, snow, etc.; surface-water, collected in ponds,
lakes, streams, etc., and in free contact with the atmos-
phere; subsoil or ground water, derived mainly from the
rain or surface water of the district, but which percolates
and flows through the subsoil, and is, therefore, not exposed
directly to the atmosphere; deep or artesian water, which
is separated from the ground water of the district by
one or more practically impermeable strata, and which
accumulates at a considerable depth below the surface.
Springs are caused by the outcropping of water-bearing
strata below the level of the water-line in them, and fur-
nish either subsoil or artesian water, according to the kind
contained in the respective strata.
Raia-water is, theoretically, the purest at our com-
mand, but in reality it takes up many impurities from the
air in its fall, especially in the neighborhood of human
habitations, and communities, and by the time it reaches
the earth contains ammonia, nitrous and nitric acid, and
in towns, sulphurous acid, soot, many bacteria, and even
microscopic plants. Moreover, the collecting surface upon
which it falls is apt to be covered with dust and impuri-
ties of all kinds, especially after continued dry weather,
which, being taken up by the rain-water, render it unfit
for use. However, if there be some arrangement for turn-
ing aside the first portion of rain that falls, it containing
the most of the impurities, and if the remainder be filtered
and stored in proper receptacles, the water may be of
excellent quality.
The main objection, however, to the sole use of rain-
water is that dependence is placed upon a very uncertain
WATER.
source, and one which is especially apt to fail when an
increased supply is most needed. The average rainfall in
Philadelphia is about thirty-nine inches per year; in very
wet years it is about one-third more, and in very dry years
about one-third less than the annual average. Each inch
of rainfall gives 4.67 gallons per square yard of area on
which it falls, equivalent to 22,617 gallons per acre.
Allowing sixty square feet of collecting surface per head,
and counting the loss by evaporation, etc., at 20 per cent.,
an annual rainfall of thirty inches would give only about
two gallons per head per day, or just about enough for
cooking and drinking purposes, and none for the other
needs of the household.
Rain-water may be collected from roofs or from a plot
of ground paved for the purpose with slate or cement, and
led by proper conduits to a cistern. It should be filtered
before passing into the cistern, while the cistern itself
should be such as to give no unpleasant taste or injurious
substance to the water, should be so situated that it will
receive no rubbish or impurities and that the water may
be kept cool, and should be cleaned regularly and often
enough to keep the water sweet and wholesome. As rain -
water contains considerable carbonic acid and other gases,
its solvent powers are marked, and cisterns should not be
lined with lead, copper, zinc, or iron, lest these metals be
taken up by the water and produce harmful results.
These remarks do not apply to the so-called rustless iron
now much used, but galvanized iron should not be used,
as it may give up zinc to the water.
Cement should be used in lining brick or stone cisterns
instead of mortar, as the latter may give up lime to the
water and render it hard. Underground cisterns for
storing rain-water should be condemned, since they are
132-4 MANUAL OF HYGIENE AND SANITATION.
liable to sewage contamination unless absolutely water-
tight. The overflow pipe from a cistern should not open
into a soil-pipe or sewer-pipe or drain, but always into the
open air, since water is so prone to take up the various
kinds of gas with which it comes in contact, and the
sewer-air might readily contaminate the entire contents of
the cistern.
Rain-water is especially valuable in cooking and wash-
ing, on account of its softness, water being called " hard"
when it contains an excess of the salts of calcium or mag-
nesium in solution. Hardness due to the presence of
calcium bicarbonate is said to be temporary, because it is
removed when the water is boiled, one molecule of car-
bonic acid being driven off by the heat, leaving the insol-
uble calcium carbonate behind. Hardness due to the other
salts of calcium and magnesium is called permanent, be-
cause it is not lost by boiling. In cooking with water
temporarily hard, the chalk is precipitated upon the sides
and bottom of the vessel and, being a non-conductor,
prevents the passage of heat, and thus wastes fuel.
Hard water may also prevent the proper softening of
certain foods, such as peas and beans, in cooking. In
washing and laundry work, the calcium and magnesium
salts unite with the fatty acids of the soap and prevent
the formation of a lather; for instance, one grain of chalk
wastes about eight grains of soap. As we do not call a
water hard unless it contains more than ten grains of
chalk or its equivalent per gallon, and as rain-water rarely
has more than one-half a grain per gallon, it is easily
understood why the latter is so valuable in the kitchen
and laundry.
A water-supply taken from rivers or smaller streams
not polluted by the refuse and sewage from towns, fac-
WATER. 133
tories, or cultivated farm lands higher np the stream, may
be fairly pure and safe to use. The best water of this
kind will be from hilly and uninhabited, uncultivated
tracts, with many small streams fed by constant springs
and uniting to form rapid creeks and rivers. Such water
may be tinged slightly with vegetable or mineral matters,
but, in general, such coloration is harmless. For storage,
dams may be thrown across convenient valleys, thus im-
pounding the water and at the same time keeping it
exposed to the oxidizing and aerating influence of the
atmosphere, and allowing the solid impurities to settle to
the bottom. Small lakes or ponds may be used to add to
supplies of this kind, provided they be not stagnant nor
have much decaying matter along their banks.
On the other hand, water from a stream which has
received the sewage from a village or town of any size,
or the refuse of factories, or the drainage from large tracts
of cultivated land, should be considered as at least suspi-
cious. Hi ver- waters are generally hard, and may contain
any of the minerals in the soils which they drain or over
which they pass; but the great danger is from impurities
of animal origin poured into them along their course. It
is not safe to depend altogether on the self-purification of
sewage-contaminated rivers, as was formerly done, though
much of the sewage and filth undoubtedly is removed,
part by oxidation by the air in the water, especially in
streams flowing over dams, rapids, etc., part by subsidence
or deposition along the banks, part by fish and animal-
culse, and much by the myria . s of the saprophytic bacte-
ria which such waters contain. If no additional pollution
is added, what is left unchanged by the above purifying
agencies is still further diluted by the supplies of pure
water that every stream receives from springs along its
134 A MANUAL OF HYGIENE AND SANITATION.
banks and in its bed, and from tributary streamlets, so
that, though the water may never be as pure as it was
originally, it may become or, by proper filtration or treat-
ment, be made a safe and usable water. But where the
proportion of filth exceeds a certain percentage, or where
sewage is being constantly added, the contained oxygen is
rapidly used up and oxidation ceases, fish and animalculse
cannot live in the water for lack of sufficient oxygen, and
though the heavier .and larger particles of the sewage sink
to the bottom or stick to the sides, they are stirred up and
set in motion by any increase in the velocity of the cur-
rent. The only remaining agents active in the destruc-
tion of the foul matter are the bacteria, and in themselves
they are often insufficient for the task, and the water thus
polluted is entirely unsafe for use.
The greatest danger from sewage contamination, how-
ever, is that it may at any time add the germs of conta-
gious disease to the water, which, multiplying rapidly, and
not being surely removed or destroyed by the ordinary
methods of water-purification, greatly increase the risks
to health from its use. It often, fortunately, happens
that, owing to the hostility of the saprophytic bacteria
of the water, or to the presence of certain chemical sub-
stances, or to other fortunate conditions, as of temper-
ature and the like, these pathogenic organisms do not
multiply as rapidly as they otherwise would, and are,
therefore, not as plentiful as one might suppose; but as it
never can be certainly told when a water so contaminated
becomes safe for use again, and as the population of most
towns and their consequent sewage production is constantly
increasing, while the quantity of water in the receiving
stream remains about the same, or is diminishing from year
to year, the use of such water should be avoided if possible.
WATER. 135
Water from large fresh-water lakes will be of the best
quality, provided it be taken from a point sufficiently dis-
tant from the shore to escape all danger of sewage con-
tamination. Chicago has apparently lowered the mortality
percentage from typhoid fever from 7.2 in 1891 to 2.1 in
1895, and 3.2 in 1896, by preventing as far as possible the
discharge of sewage into Lake Michigan, and by taking
the water-supply from the lake at a minimum distance
of one mile instead of 1400 feet from shore as formerly.
Water from small lakes or ponds, and even from storage
reservoirs, may become offensive to taste and smell through
the growth in them of minute vegetable organisms, such as
the algae, though it is not known that these are prejudicial
to health.
Ordinarily, water loses m uch organic matter as it perco-
lates through the soil, but takes up considerable carbonic
acid from the soil-air, which increases its solvent powers
so that it may take up some of the mineral constituents of
the soil through which it passes. When these mineral
substances become so great in amount as to give the water
a decided taste or medicinal properties, we call it a min-
eral water; but when the inorganic matter does not render
it objectionable to the taste or too hard, the water, whether
subsoil or artesian, will usually be considered to be quite
pure.
Attention has already been called to the pollution of
the soil. How then can the water in passing through it
lose its organic contents and become pure ? Partly by
mechanical filtration, but mainly through the combined
action of the saprophytic bacteria and the oxygen of the
soil-air, which rapidly convert the organic impurities,
both suspended and dissolved, into simpler and harmless
end-products. The substances of vegetable nature are
136 -4 MANUAL OF HYGIENE AND SANITATION.
ultimately resolved by these agencies into carbonic acid,
water, etc., while those of animal origin and containing
nitrogen, give rise to the various ammonia compounds, or
may be further oxidized into nitrous and nitric acids and
their salts, all entirely harmless in the proportions in which
they are found in the percolating ground-water.
The subsoil-water sinks through the ground till at some
level or other it reaches an impermeable stratum, where it
is retained in natural basins or escapes at some outcropping
of the stratum below the water-level, thus forming a spring.
The level of the water in these underground reservoirs
is constantly changing, according to the season, rainfall,
discharge from springs, etc., though the variation for any
given place is usually regular, and differs little from year
to year. It is from wells sunk to these water-bearing
strata and from springs that the majority of people who
do not live in towns or cities supplied by water-works obtain
their supply. These underground bodies of water are con-
stantly moving toward outlets at some point or another,
but the current is not rapid, owing to the friction and
capillary force of the particles of soil through which it
passes. For the same reason the surface of the water is
not horizontal, but curved, the curve being sharpest near
the outlet; and the difference in level between high and
low water will be least near the outlet; also, the higher
the level the greater the fall to the outlet, and the greater
the discharge.
The above remarks regarding the purity of this under-
ground water do not hold good for water from ordinary
shallow wells, under fifty feet in depth, and which do not
pass through an impermeable stratum, nor where the
water passes almost directly from surface to outlet, for in
both cases the complete filtering action of the soil and the
WATER. 137
removal of organic matter by the prolonged action of the
saprophytic bacteria are wanting. Owing to the lessening
of lateral resistance the surface- water passes almost directly
into the well (unless the wall of the latter be made water-
tight to almost the full depth), and may carry with it
solutions of all the impurities polluting the soil about the
well; and as wells drain a very considerable area — Parke
says one, in ordinary soils, whose radius is equal to four
times the depth of the well — there are few wells about
which such an area is not subject to dangerous pollution.
Moreover, the influence of pumping or other sudden with-
drawal of water from the well is even more important,
since it extends a distance from fifteen to one hundred
and sixty times the temporary depression of the water-
level, and impurities may thus be drawn into the well
which would ordinarily tend to flow away from it.
Especially about human dwellings, where wells are com-
monly located, is filth apt to be carried into the well, for
sewage and dirt of almost every kind is constantly increas-
ing in quantity in the soil about a house, with the ever-
present danger of it also receiving the specific germs of
disease.
Only such parts of this pollution as can be dissolved
may reach the water in the well, together with the bacteria
which pass freely through almost all soils when resistance
to the water current is so markedly diminished ; and it is
a strange fact that many waters thus polluted are spark-
ling and clear, with a pleasant taste and no bad odor, so
that all suspicion as to their true character may be want-
ing. Moreover, there is always danger that this contami-
nation may become so concentrated as to produce very
serious results, even though specific disease germs be
absent, and this may occur in various ways: (a) The well
138
MANUAL OF HYGIENE AND SANITATION.
may be so deep or the character of the soil such that in
ordinary weather the liquid passing through the soil is so
purified that it gives no bad properties to the water; but
if the soil is being continually infiltrated with dangerous
imparities, and if at last heavy rains or continued wet
weather supervene, there may be more and more of these
Depression of water in shallow well by pumping. A, well ; B, cesspool ; C,
underground water curve. (After FIELD and PEGGS.)
impurities dissolved and carried into the well until the pro-
portion of harmful matter in the water passes the safety
line, and we have marked illness or increased predisposi-
tion to disease among those using the water as a result; or
(6) in continued dry weather the ground-water may be
lowered to such an extent that the impurities that were
formerly well diluted become concentrated and dangerous
enough to cause sickness, even though there be no unusual
pollution of the soil about the well ; or (c) the water-level
in the well being suddenly or persistently lowered, a
greater area is drained and additional collections of sewage
may empty into the well. (Fig. 24.)
Deep wells are those over fifty feet in depth, or which
WATER. 139
go through an impermeable stratum, and do not get their
supply from the subsoil-water. Artesian wells are very
deep wells, piercing one or more impermeable strata.
Sometimes the water rises and flows out of the mouth,
in which case the well draws its supply from a water-
bearing stratum between two impermeable ones, and which
has its only outcroppings higher than the top of the well.
The water accumulates in this natural reservoir above the
level of the well-mouth, and is forced out as soon as the
opening pierces the uppermost impermeable stratum. It
is apt to be of much better quality than that from shallow
wells, since it usually represents the total percolation
through an extent of ground surface in comparison to
which the combined areas of pollution within its limits
are insignificant, the percentage of impurities in the water
being consequently reduced by dilution to much below the
danger point. It is for the same reason that there is such
a difference in the quality of spring-water and that from
most shallow wells. Though they seem to have a common
source, one is the composite water of a large district, of
which the average impurity or contamination per unit of
surface may be infinitesimal; the other is the special per-
colate from a limited area which is, for the reasons given,
particularly liable to be highly and dangerously polluted.
Artesian or deep-well water will also likely be very free
from organic matters, but possibly heavily charged with
mineral salts. Should these latter not be present, the
water will probably be of excellent quality, though if the
well be very deep, it may be too warm for immediate use
as a potable water.
Frequently well-water, and that most often from shal-
low wells, is the only kind available, especially in country
districts. In such cases care must be taken that impuri-
140 A MANUAL OF HYGIENE AND SANITATION.
ties are kept out of the well by all possible means, and if
this be done, water may often be had of safe and excellent
quality. The area about all wells should be kept clean
and the sources of all possible contamination removed.
Wells should be walled or cased, shallow wells to the
water-level, and deep wells to the first impermeable
stratum if possible, in order to cause the water to perco-
late through as much soil as possible before entering the
well. Wells should also have a good curb to keep out
splashings and drippings of muddy or dirty water.
The well should be as far as possible from any source
of contamination, especially if the latter be a constant one.
We must not forget that wells drain a large area. As the
ground-water has a constant movement in the direction of
natural outlets, the well should be so located that the cur-
rent flows jrom it toward any near-by cesspool or other
source of pollution. The direction of the underground
current can generally be determined by noting the loca-
tion of the nearest spring or water-course, by observing
the dip of the underlying strata, or by digging holes about
the well and dissolving salt or an aniline dye in them in
turn and testing the water from the well after a time for
the salt or color. If a well be much deeper than a neigh-
boring cesspool, it may drain from the latter, even against
the ground-water current, especially if the water in the
well be suddenly lowered. Again, dangerous impurities
have sometimes been carried into wells from long distances
through fissures or crevices in the rock.
The water from the well should be frequently tested for
chlorides and nitrates, these indicating sewage contamina-
tion, and this should be done especially after heavy rains
and also when the water in the well becomes low. The
taste and odor of the water should also be noted after
WATER. 141
standing or being heated. Some other source should be
sought whenever the tests show contamination, or when
there are cases of infectious disease near at hand. Boil-
ing the water and filtration are always to be recommended.
Wells in thickly settled towns should not be used to
supply drinking- or cooking-water, as the soil is always
more or less saturated with filth and sewage, and it is prac-
tically impossible in such places to locate a well which
will not be in constant danger of receiving harmful im-
purities.
The decision as to the quality of any water must in
each case be determined by all the circumstances available
which relate to it, and these should all be thoroughly
investigated before rendering an opinion, as some of them
may counteract the others. However, other things being
equal, the value of a water will probably be in accord
with the following table:
f 1. Spring- water, | Very
Wholesome \ 2. Deep well-water, palatable.
v. 3. Water from unpolluted streams, I Moderately
Suspicious / 4. Stored rain-water, palatable.
<. 5. Surface-water from cultivated land, ~|
Dangerous { 6- Sewage-polluted river-water, j- palatable.
I 7. Shallow well- water.
A good potable water should be perfectly clear, free from
odor or taste, cool, well aerated, and, if possible, soft, or
with only a mild degree of hardness. Circumstances must
determine the amount of dissolved matters permissible;
what is an excess in one case might not be so in another.
We may also classify waters as follows : 1. Pure and
wholesome water. 2. Usable water. 3. Suspicious water.
4. Dangerous water. (See table on page 179;) Pure waters
and usable waters may be used without filtration; those
of the third class should be filtered before distribution,
and also at the house before use, if possible, and a purer
142 A MANUAL OF HYGIENE AND SANITATION.
source sought out or all sewage-pollution prevented.
Those of the fourth class should not be used at all except
when it is absolutely unavoidable, and then only after
purification by all the means at command.
Inasmuch as most large cities must from necessity fur-
nish a water of the second or third, and occasionally even of
the fourth class, such water should be purified as much as
possible before distribution, by storage for a time in settling
reservoirs and by some effective system of filtration, com-
bined with chemical treatment, if necessary. As much of
the organic matter is oxidized, and many of the patho-
genic bacteria are destroyed by saprophytes and other
causes while the water is standing in the settling-reser-
voirs, a water originally suspicious or worse may often be
made quite usable by the above means properly employed.
Not only must the storage reservoirs and filtering appa-
ratus be kept clean, but care must be had that the dis-
tributing apparatus does not allow soil- or sewer-air or
sewage to be drawn in through leaks in the mains at
times when the flow is intermittent, and that lead pipes
are not used in the houses if the character of the water is
such that it acts on that metal.
Diseases Caused by Impure Drinking-water. A
polluted water may carry the organisms of infectious dis-
eases, or it may produce or favor the development of
diseases which are not due to specific germs. In addition
to this, and of at least equal importance from a sanitary
point of view, is the depressed state of the system that the
habitual use of impure drinking-water causes, and the
predisposition to disease that ensues. By the power of
accommodation and through long habit, a community may
become so protected against an impure water as to mani-
fest no striking symptoms, while strangers may be seri-
WATER. 143
ously affected by it; but even in such a case, the condition
of those habitually using the water will be apt to be
depressed and far from good.
The non- infectious diseases likely to be caused by im-
purities in the drinking-water are primarily those affecting
the alimentary tract, as dyspepsias, diarrhoeas, and other
disturbances having their origin in severe gastric or intes-
tinal irritation. So, also, impure water, even though it
do not contain the actual germs, may have much to do
in bringing on an attack of specific dysentery by so irri-
tating the lower intestine as to make it especially receptive
to the cause of the disease when introduced from another
source.
Large quantities of the sulphates of calcium and mag-
nesium are thought to have special influence in causing
dyspepsias, with loss of appetite, pain at epigastrium, etc.
An excess of iron in water is also prone to produce con-
stipation, headache, loss of appetite, and malaise. Goitre
and the formation of vesical calculi are each supposed to
be due to mineral or inorganic impurities, though the true
relation of impure drinking-water to these diseases is still
unsettled. " It has long been a popular opinion that
drinking lime-waters gives rise to calculi of the oxalate
and phosphate of calcium/' and the " opinion that impure
water is the cause of goitre is as old as Hippocrates and
Aristotle." Further study of the principles underlying
the new treatment of goitre with glandular extracts may
make it easier to determine whether bad water has or has
not a causative influence in the .production of the disease.
Diarrhoea may be produced by any of the following
impurities in water: Suspended substances of any kind,
but especially those of fecal origin; dissolved animal,
vegetable, or mineral matters, and fetid gases. The diar-
144 A MANUAL OF HYGIENE AND SANITATION.
rhoea produced by any of these contaminants may be so
severe as to simulate true dysentery and cause doubt as to
the diagnosis.
Certain, metals may be taken up from the earth's strata,
or from the lining of cisterns, and may produce their char-
acteristic and poisonous symptoms in the system. Lead is
one of these metals, and it will be well to note here the
waters that are especially apt to take up this metal. Pure
waters and those containing much oxygen act most power-
fully on lead, as do those containing organic nitrates and
nitrites, especially ammonium nitrate. Waters containing
carbonic acid and the salts of lime and magnesia and
those free of absorbed gases act least on lead, and car-
bonic acid seems even to protect lead by forming an insolu-
ble carbonate on its surface. Lead is mote easily dissolved
if other metals are in contact with it, probably owing to
electrolytic action. Lead should not be used for pipes
nor to line cisterns unless suitable tests show that the
water does not affect them, nor should any water be used
in which the tests show more than one-twentienth of a
grain of lead per gallon. Even water containing carbonic
acid may take up lead for a time from new pipes until the
insoluble carbonate is formed within them.
Of the infectious diseases, germs of typhoid fever,
cholera, dysentery, and malaria are usually carried into
the system by the drinking-water, while the same is often
true of yellow fever, scarlet fever, diphtheria, and kin-
dred diseases. But, as with the impurities causing non-
infectious diseases, water containing disease germs may
sometimes be used for a long time by those accustomed to
it without the development of the specific malady, and it
may only be after the system is weakened by excesses or
other predisposing conditions that the diesase manifests
WATER. 145
itself; or it may happen that only strangers and non-
acclimated inhabitants incur the disease. It has been sug-
gested that this immunity is probably brought about by
the very gradual introduction into the body of the disease
germs and their poisons, so that old residents are not
susceptible to the quantities of either of these which are
sufficient to give rise to the particular diseases in new-
comers.
Many instances have been recorded which practically
prove the transmissibility of infectious diseases by means
of drinking-water, and of these reference may be made to
the epidemics of typhoid fever at Lausen,1 in Switzerland,
and at Plymouth, Pa. ;2 of malaria on board the transport
ship "Argo";3 and of cholera in London.4 The writer
himself had an opportunity of investigating an epidemic
of typhoid fever in a small village in North Carolina.5
In this there were only four or five in about sixty cases
which were not undoubtedly due to the contamination of
the subsoil-water by the infected excreta from the first
case; and of four exceptions, which were all in one family,
the first was in all probability infected while in attendance
upon sick neighbors. It was also shown that with the
exception of these four, the cases all developed directly
along the lines of natural drainage leading from the resi-
dence of the original case — a boy, who came to the village
sick with the disease — and that the latest cases to develop
were those most remote from the starting point of the
infection.
Moreover, in most large cities of this country the
1 Pepper's System of Medicine, vol. i. p. 250.
2 Robe's Text-book of Hygiene, 2d edition, p. 63.
s Parke's Hygiene, 8th edition, p. 64, and Rone, p. 60.
* Rone, p. 64. s University Medical Magazine, May, 1892.
10
146 A MANUAL OF HYGIENE AND SANITATION.
typhoid fever death-rate is accepted as the direct index
of the character of the water-supply; and it seems to be
a fact almost without exception, that any marked improve-
ment in the latter will be followed by an immediate and
positive reduction in the former. The same may also be
said to hold good in regard to diarrhoeal diseases, while in
eastern North Carolina there has been a very marked
reduction in the prevalence of malarial fevers as a result
of the efforts of the State Board of Health to persuade
the people to substitute rain- or deep well-water for the
subsoil-water, which was almost universally used a few
years ago.
The ova of certain parasites, such as tape- or round-
worms, may often be taken into the system with the
drinking-water, and these upon developing may cause
disturbances more serious than the slight attention usually
given to them would seem to indicate. Any attack of
convulsions in a child or other manifestation of severe
reflex action should lead to the inquiry as to whether
these parasites may not be present and whether the water-
supply has not been a source of invasion.
Regarding the foregoing remarks, Parkes makes the
following statements : " 1. An epidemic of diarrhoea in a
community is almost always owing to either impure air,
impure water, or bad food. If it affects a number of per-
sons suddenly, it is probably owing to one of the last two
causes, and if it extends over many families, almost cer-
tainly to water. But as the cause of the impurity may
be transient, it is not easy to find experimental proof.
2. Diarrhoea or dysentery constantly affecting a commu-
nity, or returning periodically at certain times of the year,
is far more likely to be produced by bad water than by
any other cause. 3. A very sudden and localized out-
WATER. 147
break of typhoid fever or cholera is almost certainly owing
to the introduction of the poison by water. 4. The same
fact holds good in malarial fevers, and, especially if the
cases are very grave, a possible introduction by water
should be inquired into. 5. The introduction of the ova
of certain entozoa by means of water is proved in some
places, probable in others. 6. Although it is not at
present possible to assign to every impurity in water its
exact share in the production of disease, or to prove the
precise influence on public health of water which is not
extremely impure, it appears certain that the health of a
community always improves when an abundant and pure
water-supply is given; and, apart from this actual evi-
dence, we are entitled to conclude from other considera-
tions that abundant and good water is a prime sanitary
necessity. J ' The statistics already given and those to come
in later pages are confirmatory of the correctness of this
last assertion ; and sanitary authorities now realize that the
main cause of an increase in the death-rate of diarrhoeal
diseases is more often to be fairly attributed to a bad water-
supply than to improper food or untoward temperatures.
Even with respect to cholera infantum (which is generally
supposed to be principally due to the influence of exces-
sive heat upon the infant .and its food), a number of epi-
demics show a closer relation to impure water-supply than
to temperature changes.
The Purification of Water. Impurities in water may
be either solid matters in suspension, or dissolved sub-
stances, and may be organic or inorganic. Any turbidity
is due to solid particles, and water free from these is clear,
though it may have a color more or less deep from dis-
solved matters. Moreover, a clear water may contain such
solid bodies as bacteria, ova of parasites, etc., which are too
148 A MANUAL OF HYGIENE AND SANITATION.
minute to be seen with the naked eye. "Whether harmful
or not, all impurities should be removed in so far as is pos-
sible from all supplies of drinking-water. This may be
done to a considerable extent with large volumes of water
before it is distributed to consumers, and should always be
attended to by the latter if the water is not already clean
and within the limits of safety when they receive it. In
fact, a large city at the present time can scarcely have a
more important subject for consideration than that of
obtaining the purest possible water-supply for its people.
There is always a tendency among many to allow matters
to continue as they are, or as they have been in the past;
and a decided objection by others to incurring additional
expense for what may seem to them only aesthetic reasons;
but, no matter what may be the cost of providing a reason-
able supply of pure water for any large city's personal and
domestic uses, a very little consideration will show that
such expenditure is true economy from solely a financial
point of view, even though we ignore the misery and sor-
row of the sickness and deaths that are due to the use of
a polluted water.
As has been stated by the excellent authority quoted
above, " the health of a community always improves
when an abundant and pure water-supply is given.77
" The death of 3400 persons from cholera followed the
temporary supply of unfiltered water by the East London
Water Company in 1866, while the rest of London remained
nearly free from the disease,77 and in 1892 " Hamburg
lost 8605 citizens from the same disease alone,77 regarding
which " the health authorities found that the principal
cause of this epidemic was the polluted water-supply.77
i Hazen : The Filtration of Public Water Supplies, 1895.
WATER. 149
Again, after the scourge of typhoid fever in Plymouth,
Pennsylvania, in 1885, when there were 1104 cases and
1 14 deaths within a few weeks in a population of 8000, as
a result of the pollution of the water-supply by a single
person, great care was taken to determine the exact cost of
the " visitation/7 as some would term it. It was found
that the actual expenditure for the care of the sick was
$67,100.17; for loss of wages by those recovering, $30,-
020.08; a total of $97,120.25, to which should be added
a number of times the $18,419.52 that those who died
were earning per annum when taken sick. How much
cheaper in comparison would a protecting filter-plant have
been ! But overlooking special epidemics, and considering
the average annual typhoid death-rates of our cities, we
find that experience both here and abroad shows that
with a pure water-supply a fair death-rate from this dis-
ease is 25 per 100,000, and that any city may reasonably
expect to secure such a rate by observing proper precau-
tions. And yet only eight cities of over 50,000 popula-
tion whose mortality returns were given in the United
States Census Reports of 1890 had so low a figure. On
the other hand, there were five cities of over (and two of
less than) 50,000 that had 100 or more deaths per 100,000,
all using unfiltered river-water. The remaining forty-one
of those above 50,000 had rates varying from 26 to 98.
Counting each death as a loss to the community of $5000 —
not an excessive estimate according to the finding of courts,
and since most typhoid cases occur during the working age
of from fifteen to fifty years — " the saving due to filtration "
on the unnecessary deaths from typhoid fever " would
have paid for the entire cost of filters in the first year
they were in use" in the first seven of these cities; " in
sixteen others, with an aggregate population of 3,717,560,
150 A MANUAL OF HYGIENE AND SANITATION.
filtration would have paid for itself in two years or less/'
and in " eighteen others with an aggregate of 3,238,617,
filtration would have saved seven or more lives per 100,000
annually, and would have more than paid for the interest
and cost of operating the filters."
Lawrence, Mass., with a population of 44,654 in 1890,
built a filter at a cost of $67,000, and saved enough lives,
at $5000 per head, to pay for it within the first four
months that it was in use. In Chicago, when the simi-
larly estimated loss from typhoid deaths in the city and
suburbs amounted to over $10,000,000 in 1891, the aban-
doning of a shore inlet near the mouth of the sewage pol-
luted Chicago river in 1892 resulted in a reduction of 60
per cent, in the typhoid mortality during the following
year. Philadelphia also had a typhoid-fever mortality
rate of 40 per 100,000 in 1895, and of about 32 in 1896
and 1897, representing a preventable death-loss, as above
calculated, of from $400,000 to $850,000; whereas an
extremely competent authority has estimated (September,
1896) that the first cost of installing filters with all neces-
sary accessories capable of giving an average daily supply
of 100 gallons and a maximum of 150 gallons per capita
for the whole population would be only about $3,000,000,
and that the annual expense for operating these filters would
only be $166,000, the total annual outlay on the whole
capitalization thus being actually less than the death-loss
from one disease for one year. Nor must it be forgotten
that these figures do not include the cost of medical atten-
tion and nursing, nor the loss of time and employment by
those that recovered, nor do they consider the financial
loss due to sickness and deaths from other diseases than
typhoid fever that may be fairly credited to polluted
water-supplies. Can any one doubt where true municipal
WATER. 151
economy lies, and is there not abundant opportunity for
sanitary education and work in this direction alone for
many years to come ?
Purification before distribution may be by either or all
of three methods: subsidence, chemical treatment, and
-filtration.
The first method consists in allowing the water to stand in
large reservoirs till the greater part of the suspended mat-
ters have fallen to the bottom. If sufficient time be given,
much of the organic matter, whether solid or dissolved,
will be decomposed or reduced to simpler compounds by
the action of the sunlight, oxygen, animalcule, sapro-
phytes, etc. Most of the bacteria, also, especially the
pathogenic species, will disappear either by sedimentation
or by death from lack of favorable conditions. Conse-
quently, a water originally quite impure may be much
improved by this method alone, while if it is used in con-
junction with and preliminary to filtration, it will be addi-
tionally advantageous, in that it reduces the cost of the
latter by lessening the frequency and cost of cleaning the
filters.
What the capacity of the reservoirs and the time of
storage should be depends on circumstances. If it is the
only method of purification employed, and especially if
the water is very foul, the longer the time of storage the
better. Again, if the source of supply is variable in out-
put, or if it is liable to excessive pollution for limited
periods, the capacity should be such, if possible, that
water need not be collected during the emergency. On
the other hand, if the water is to be subsequently filtered,
the capacity of the reservoirs and time of storage need not
be so great. Most German authorities on filtration hold
that sedimentation for twenty-four hours or even less is
152 A MANUAL OF HYGIENE AND SANITATION.
sufficient, most of the solid matters being precipitated
within that time, if at all, and the filters being relied upon
to remove the remainder, especially the finer particles and
the bacteria. The English practice is to store the water
for a longer time, though local causes related to the source of
supply are the reason for this. Thus the Lea and Thames,
from which "the London companies take much of their
water, are subject to extra pollution in times of flood,
which are usually of short duration, and a sufficient reserve
for such periods is of obvious value.
All storage reservoirs should, of course, be kept free
from extraneous contamination and should be cleaned
from time to time. Weeds should be destroyed, as they
sometimes give a bad taste to the water. The water may
also have a bad taste or odor from algse and other species
of minute plants, which especially favor a pure water
exposed to sunshine. They are not known to be harmful,
but it may be necessary to cover the reservoirs to get rid
of them and their unpleasant properties.
Where a water is very hard or contains an excess of
mineral matter, it is frequently of advantage to treat it
chemically. If the hardness is due to the bicarbonate of
calcium in excess, it may be removed by the addition of
a solution of calcium hydrate to the water, the insoluble
carbonate of calcium being formed and precipitated. The
change is represented by the equation: CaOCO2CO2 -|-
Ca(HO)2 = 2CaCO3+H2O. Clark' s process, based on this
reaction, is as follows: About fourteen or fifteen hundred-
weight of lime is allowed to each million gallons of water,
the actual quantity of lime depending on the amount of
carbonate in the water. The lime is slaked in a tank into
which the water to be treated flows; the mixture is well
stirred and then allowed to stand for twelve hours, when
WATER. 153
the supernatant water is drawn off, the tank cleaned and
the process repeated. The water is not only softened in
this way, but the precipitate usually carries down with
it much of the solid impurities and organic matters in the
water. This process is extensively used in England, where
much of the available water is derived from the underly-
ing chalk beds, and thus has a superabundance of the
bicarbonate; but the writer is unaware that it finds any
general application in this country, though it might be an
advisable method of treatment in certain of our limestone
districts.
If alum (sulphate of alumina) be added to an impure
water, a decomposition of the salt occurs, the acid portion
combining with the bases in the water and forming a
flocculent precipitate of insoluble basic sulphates and alu-
minum hydrate, which entangles in it and carries down
the suspended impurities in the water, besides remov-
ing much of the dissolved organic and coloring matters.
Moreover, careful experiments have shown that the addi-
tion of only about one grain of alum per gallon, followed
by thorough agitation and subsequent settling for twenty-
four hours, will almost invariably give a water free from
germs and one that will tend to remain sterile for a con-
siderable time; this possibly being due to the removal of
the food-supply of the bacteria.1
The use of alum is especially advantageous when a
water contains a very fine silt or the like in suspension,
and which is not removed by subsidence even after a con-
siderable time. It is also to be used in conjunction with
or preliminary to mechanical filtration, which latter, at
the usual rate of operation, is oftentimes practically de-
i V. and A. Babes : Centralblatt fur Bakteriologie und Parasitenkunde, 1892,
vol. xii., No. 45.
154 A MANUAL OF HYGIENE AND SANITATION.
pendent upon alum for the furnishing of a safe water.
Comparatively little alum is needed, usually not more
than one, or at most two, grains per gallon, even with a
very dirty water, and if the supply is practically adjusted
to the condition of the water, as it should be, the extremely
minute quantity of free alum that may sometimes pass
through the filters is harmless and unimportant.
Should the water be lacking in sufficient bases, which,
however, is extremely improbable, it might contain when
filtered a very little free acid, which would be readily
neutralized by the addition of a correspondingly small
quantity of soda, the resulting salt affecting neither the
healthful ness nor the palatability of the water. It has
been suggested that the alum be first decomposed by the
addition of soda, then washed free from the resulting
sodium sulphate, and the flocculent hydrate of alumina
added to the water, thus avoiding the danger of either
free alum or acid in the cleared water; but experiments
show that the results are not as good as when alum alone
is used.
Regarding the danger from the use of waters purified
by the addition of alum, Hazen says : "Although alum
in large quantities is undoubtedly injurious to health, it is
neither a violent nor a cumulative poison; and the propo^
sition that one part of alumina in a million parts of water
is injurious to health must be regarded as conjecture rather
than as a matter of proof, or even of probability.'7
The Anderson process, which consists in the agitation
of the water with metallic iron before filtration, is em-
ployed at Antwerp and elsewhere; but it is not clear that,
with large quantities of water, better results are obtained
than by simple filtration. The idea is that some of the
iron is converted into soluble ferrous carbonate, which
WATER. 155
then oxidizes to insoluble ferric hydrate and carries down
with it the suspended and many dissolved impurities, and
thus facilitates their removal by sedimentation and filtra-
tion. The difficulty in using this process on a large scale
seems to be that the carbonate is not formed quickly
enough, and also that too much of the iron may remain
in solution even after filtration.
Filtration. For the purification of large quantities of
water, such as are needed for great cities, there can be no
question that sand filtration is, in the majority of cases,
the most available, satisfactory, and efficient method,
though it may often be advantageously preceded by sedi-
mentation or by chemical treatment, as already described.
The former especially, by removing much of the sus-
pended matters, will prolong the use of the filters between
cleanings, and thus materially lessen the cost of mainte-
nance; while the latter may greatly improve the chemical
quality of the filtered water.
Municipal filters of the type to be described are as yet
not widely known in this country, but they have been used
abroad with increasingly good results for upward of half a
century, and they now furnish the daily supply of water
to more than twenty millions of people. However, we
may take credit in the knowledge that the most thorough
and scientific investigation of their action and efficiency
has been made on this side of the Atlantic under the
auspices of the Massachusetts State Board of Health, and
that it is to this body that we are indebted for much of
the positive information that we now have concerning
them.
The limitations of this work do not permit a full dis-
cussion of the principles or merits of such filters; but the
following details are given that the reader may appreciate
156 A MANUAL OF HYGIENE AND SANITATION.
the simplicity of their construction and the efficiency of
their work. Those desiring more extended information
are referred to the Massachusetts reports that discuss this
subject, and to the excellent work of Dr. Hazen, already
mentioned,1 from which many of the accompanying state-
ments and the illustrations have been taken.
Almost without exception these filters now consist of a
layer of clean sand of a certain degree of fineness spread
upon a layer of gravel in a carefully prepared basin, the
whole being underdrained and proper arrangements made
for the controlling of the depth of water upon the surface,
rate of flow of the filtrate, cleaning of filters, etc.
Such filters act primarily as strainers to remove the
solid impurities from the water, but their efficiency is
much increased by the sediment itself that is retained
upon the surface of the sand, and which forms a filter
much finer than the latter and is capable of mechanically
preventing the passage of most of the bacteria always
present in a surface-water. It was supposed until com-
paratively recently that this removal of the bacteria was
largely due to the organisms themselves in the sediment
layer, and that by forming a felt-like growth they not
only increased the fineness of the strainer, but that by
acting as saprophytes they decomposed much of the
organic matter, and even killed the pathogenic bac-
teria. However, it now seems probable that for con-
tinuous filters the action is mainly mechanical, removing
suspended matters and bacteria, and but slightly affecting
the dissolved organic matters. On the other hand, in
intermittent filtration, where the conditions more nearly
resemble those taking place in the soil, and where the
i Filtration of Public Water Supplies.
WATER.
157
filters are periodically aerated, the straining action is less
perfect on account of the greater rate of nitration neces-
sary, but the nitrification and destruction of organic matter
due to the action of the saprophytes and oxygen are greater.
Intermittent filters might, therefore, prove to be the better
for the purification of sewage or a very impure water,
though usually their efficiency in removing bacteria seems
to be inferior to that of continuous filters.
The location of the filter beds with respect to the source
of supply and the storage reservoirs will depend largely
on local conditions, economy in cost of pumping, etc.
Settling tanks are almost essential where the water to be
filtered is very turbid, even at intervals. Reference has
FIG. 25.
General arrangement of filter plant.
already been made to the difference of opinion between
English and Continental authorities regarding the size of
these settling basins. As the filtration does not remove
hardness due to dissolved matters, it may also be advisable
to use the Clark process previous to sedimentation and
filtration. Part of the color due to peat or vegetable
matters is removed by ordinary filtration, and still more
may sometimes be taken away by the previous addition of
alum, but such preliminary treatment is unusual. Where
the water comes from a lake or from a river with a slow
current, settling basins are, of course, unnecessary.
158
MANUAL OF HYGIENE AND SANITATION.
Inasmuch as it is needful to govern the depth of the
water upon the filter-beds, and to prevent the disturbance
of the sand and sediment layer by the force of the enter-
ing current, some method of regulating the inflow is neces-
sary. The accompanying illustration shows a compara-
tively simple arrangement for this purpose.
FJG. 26.
0 5 10 15 20 Feet
Regulation of inflow used at Hamburg.
The total area of the filter-beds will depend upon the
amount of water needed, the rate of filtration, and the per-
centage of area out of use while being cleaned. The total
area is to be divided into beds varying in number accord-
ing to circumstances, so that one or more of these beds
may be cleaned while the rest are in use. Large beds
decrease the cost per acre, on account of less masonry, etc.,
being needed, but it may be more difficult to maintain an
even action over the larger areas. This latter point is,
however, largely governed by the size and arrangement
of the underdrains.
The walls and bottoms of filter-beds should be made
water-tight, that there may be no waste of the filtered
water on the one hand, nor any ingress of foul soil-water
WATER. 159
on the other. The form of the filter-bed is immaterial,
provided evenness of work over the whole area is not
impaired. Where the mean January temperature is below
the freezing point the beds should be covered, as the
formation of ice upon them seriously impairs their effi-
ciency, and as, moreover, a number of epidemics of typhoid
fever and certain intestinal diseases seem to be directly
traceable to ice-formation. This may have been on account
of the overtaxing of the filters through increased difficulty
in working, or because the sedimentation layer and the
sand were disturbed in the removal of the ice.
As already stated, the materials" used practically every-
where are clean sand and gravel, and the sharper the sand-
grains the better. At the Lawrence Experiment Station
of the Massachusetts State Board of Health " the size of
a sand-grain is uniformly taken as the diameter of a sphere
of equal volume, regardless of its shape. " Moreover, as
it is " the finest portion which mainly determines the char-
acter of sand for filtration/7 the effective size is taken to be
<( the size of a grain such that 10 per cent, by weight of
the particles are smaller and 90 per cent, are larger than
itself.77 As uniformity of grain is also important, the
uniformity coefficient is " the ratio of the size of grain
which has 60 per cent, of the sample finer than itself to
the size which has 10 per cent, finer than itself.77 Obvi-
ously, the velocity of water through a layer of sand will
depend upon the effective size of the sand, the thickness
of the layer through which the water passes, and the loss
of head or f rictional resistance of the sand. A rise of
temperature also causes a progressive increase in velocity.
The effective sizes of sand-grain in use in most of the
foreign filters average from 0.31 to 0.40 mm. In general,
it may be said that the finer the sand, the better is the
160 A MANUAL OF HYGIENE AND SANITATION.
quality of the normal filtrate and the less the danger of
an unsafe effluent in case the sediment layer is broken;
but, on the other hand, cost of filtration increases with the
smallness of sand-grain, since the filters must be cleaned
oftener and fine sands are harder to wash, as well as
because the velocity of flow is slower through fine sands.
All things considered, the best results will probably be
obtained with a sand having an effective size of from
0.20 to 0.35 mm. and a uniformity coefficient of not more
than 3, the lower the latter the better, and the selection of
the former depending largely upon the character and clear-
ness of the water to be filtered.
The thickness of the sand layer should be such that it
may be scraped a number of times before becoming so thin
as to require refilling. The German Imperial Board of
Health requires a thickness of at least twelve inches after
the last scraping; while the original thickness should be
from twenty-four to forty-eight inches, the thicker the
better, provided the cost of the filter be not made too
great and the rate of filtration be not too much dimin-
ished. The sand should be of the same degree of fineness
throughout.
As for the gravel beneath the sand, there is no reason
why it should be of excessive thickness. A depth of one
foot is probably sufficient, provided the stones are of vary-
ing size, so arranged that the sand above will not work
into and through the interstices, and that the water may
freely enter the underdrains at low velocity. The loss of
head in water flowing through a thin layer of gravel prop-
erly placed is comparatively slight. Foreign filters do
have a gravel layer of two feet or more in thickness, as a
rule, but careful experiments at Lawrence, Mass., show
that this depth is entirely unnecessary, provided that the
WATER. 161
gravel is properly laid as indicated, and that the under-
drains are not too far apart.
The underdrains should be of such size and so con-
structed that the frictional resistance which they offer to
the flow of the water is only a small percentage of that
of the clean sand, and that the rate of nitration is the same
over the whole area of the filter. There is usually a main
drain along the middle of the filter floor with smaller
parallel lateral drains leading into it at regular intervals.
The drains may be made of brick with open joints, or, for
the laterals, of tile, which is usually cheaper. Care must
always be had that the openings are sufficient in number
and size freely to admit the water.
The area drained should vary from about 300 square
feet for a four-inch lateral drain to 4400 square feet for a
twelve-inch main, the velocity of flow in these being
respectively 0.30 and 0.51 foot per second; while larger
drains should have a cross-section of at least one-six-thou-
sandths of the drained area. The European custom of
ventilating drains by means of pipes passing up through
the sand and water above is not to be commended, since
such ventilation apparatus is unnecessary, increases the
cost of the filters and, what is worse, may allow impurities
to contaminate the filtered water in the drain. Recently
it has been suggested that the filter-beds be constructed
directly over the storage reservoirs for the filtered water,
the beds being supported on suitable steel columns resting
on concrete foundations in the bottom of the reservoirs.
The bottom layer of gravel or broken stone would rest on
steel tubes or bars several feet above the level of the
water in the reservoir, thus allowing the filtrate to be
aerated as it falls through the intervening space. Theo-
retically it would seem that the plan is a good one, and
11
162 A MANUAL OF HYGIENE AND SANITATION.
actual results indicate that it practically is so. Some of
the advantages are the absence of underd rains and loss of
the resistance factor due to them, the aeration of the
nitrate as indicated, and also the practically continuous
aeration of the filter-bed itself, thus enabling the sapro-
phytic bacteria in the upper layers to carry on their work
of oxidizing and nitrifying the organic impurities of the
water.
The depth of water upon the filter-beds must be regu-
lated according to the rate of flow desired, the thickness
and resistance of the sand, etc. Although it has been the
FIG. .27.
Simplest form of regulation. Stralau filters at Berlin.
custom to keep the depth in excess of the loss of head,
this is not essential. On foreign filters the usual depth is
from thirty-six to fifty-two inches, though less than this
might suffice in many instances. The necessity of regu-
lating the inflow and of maintaining a constant level must
not be overlooked if uniform results are desired.
Summarizing the preceding statements, the rate of filtra-
tion and loss of head will depend upon the depth of water
WATER. 163
on the filters, the thickness of the sand-layer, size of sand-
grains, resistance of underdrains, temperature, etc., and
all these will likewise affect both the cost and the efficiency
of the filtration.
Two million gallons per acre per day will probably be a
safe rate of filtration to maintain continuously, though with
a clear water or in emergencies a rate one-half greater will
very likely not materially alter the quality of the filtered
water or increase the risk. But in general, as the rate
increases the efficiency decreases. Where the filters are
constructed above the storage reservoirs in the manner
described, it is claimed that much larger quantities of
water may be filtered in the given time with equally good
results. If this be so, it is probably due to the increased
saprophytic and oxidizing action resulting from the con-
tinuous aeration of the filter.
As the sediment accumulates and deepens upon the sur-
face of the sand, the rate of flow necessarily diminishes,
and it becomes necessary after a time to remove the de-
posit. This is done by carefully scraping off the top
layer of the sand to the depth of from one-half to one
and one-half inches, repeating the scraping as often as
may be necessary until the thickness of sand above the
underlying gravel is near the permissible minimum.
Then the sand which has been removed, and which has
meanwhile been thoroughly washed by a stream of the
filtered water, driven, if necessary, by a force-pump is care-
fully replaced, packed, and levelled upon the beds. How-
ever, these do not attain their greatest efficiency until a cer-
tain amount of sediment from the water has collected upon
them, and it is, therefore, not wise to use the filtered water
for some time after the cleaning and until bacteriological
tests show that the maximum purification is being attained.
164 A MANUAL OF HYGIENE AND SANITATION.
Domestic Purification of "Water. Boiling destroys
living organisms and disease germs; it also drives off the
carbonic acid and other gases of the water, and causes the
precipitation of many mineral substances held in solution by
these gases. This is especially the case, as has been stated,
where the water is hard from the presence of calcium
bicarbonate in excess, but iron is also often thrown down
by boiling. If the water contains a very fine sediment, not
removed by settling or filtration, it may be advantageous
to add a little alum and chalk to produce the flocculent
precipitate already described. Potassium permanganate
has little effect in purifying a foul water. Agitation with
iron filings may do a little good by favoring oxidation of
organic matters. Tannin is thought to destroy micro-
organisms, and a harmful water may sometimes be made
usable • by boiling with tea leaves or other astringents.
Citric acid is said to destroy algae. Aeration and agitation
improve a water after distillation or boiling by restoring
oxygen and also by oxidizing organic matters. Eemem-
ber that boiled water is prone to take up gases of any
kind, whether impure and offensive or otherwise. Organic
matters are got rid of by boiling, exposure to air, agita-
tion, addition of alum, astringents, charcoal, etc. ; bicar-
bonate of lime, by boiling or by adding caustic or slaked
lime; iron, by boiling and by adding lime-water. Cal-
cium and magnesium sulphate and chloride cannot readily
be removed. Some plants help to purify by means of the
oxygen which they give to the water.
House filters are dangerous unless properly cared for,
and may give more and worse impurities to the water
than they take from it. What a filter takes from a water
is left in the filter, unless otherwise removed, and an accu-
mulation of such impurities cannot improve the water
WATER.
165
passing through them. The organic matters will undergo
decomposition and putrefaction, and will furnish a good
culture medium for bacteria, and these together with the
putrefaction products will, in most cases, be carried through
the filter with and by the filtered water. A filter has no
miraculous power to annihilate filth, and, moreover, the
size of a filter must always limit the work it can do, what-
ever the materials used.
According to Parkes, the requisites of a good filter are :
1. That every part shall be easily accessible for cleansing
or renewing the medium. 2. That the filtering medium
have a sufficient purifying power and be present in suffi-
cient quantity. 3. That the medium give nothing to the
water favoring the growth of low forms of life. 4. That
the purifying power be reasonably lasting. 5. That there
be nothing in the construction of the filter itself capable
of undergoing putrefaction or of yielding metallic or other
impurities to the water. 6. That the filtering material
FIG. 28.
Tubes of unglazed porcelain for Pasteur filter.
shall not clog, and that the flow of water be reasonably
rapid; to which may be added : 7. That the filtering me-
dium be such that it can be readily cleansed and sterilized,
or else so cheap that the removal and replenishing may
not be neglected when necessary on account of the expense.
House filters may be divided into three classes : (a)
Those entirely disconnected from the water-supply pipes
of the house; (6) those connected with the water-pipes,
166 A MANUAL OF HYGIENE AND SANITATION.
but intended to filter only a limited quantity, as for
drinking, cooking, etc.; (c) those connected with the
house service-pipe and intended to filter all the water used
in the house. The same filtering media may be used in
all three classes, but it will be found best in the first two
to employ substances through which the water passes
slowly, while the latter class must necessarily filter the
water more rapidly in order to yield a sufficient supply.
FIG. 29.
Berkfeldt filter attached to tap.
It will often be advantageous to have a settling tank con-
connected with those of the first class, to prolong the safe
use of the filter as long as possible; while the same object
is gained in some of the second class by bringing the water
in at the bottom, in which case there should be a space
below the filtering medium to allow the suspended matters
to fall away from the latter. Those intended to filter the
whole supply of the house are generally cleansed by
reversing the current and washing the collected dirt out
of the filter into a drain or sewer, the first water passing
WATER.
167
through the filter after this is done being also discarded.
In such filters the quantity of filtering material should be
sufficient thoroughly to purify the water passing through
FIG. 30.
Pasteur filter with reservqir for filtered water.
it, and yet should not be so heavy that the reverse or
washing current 'cannot lift it and separate the particles
so that by their scouring action upon one another they
may be cleansed and all the dirt washed out. These
168
MANUAL OF HYGIENE AND SANITATION.
filters, also, may be so arranged that a small quantity of a
coagulant, like alum, is automatically added to the water
before filtration. If this be done, care must be had to
supply no more of the coagulant than suitable tests show
to be necessary, else the excess may be carried through the
filter in solution.
FIG. 31.
Multiple Berkfeldt filter with self-cleansing attachment.
No matter what kiud of filter is used, the drinking-
water should always be boiled in times of epidemics, or
when the water before filtration is especially impure; for,
though the Berkfeldt or the Pasteur-Chamberland filter,
and possibly a few others, are practically bacteria proof,
WATER. 169
there always remains a possibility that disease germs may
by some means pass through the medium or gain access to
the water after it is filtered. The writer's own opinion is
that with most good filters that are regularly and frequently
cleaned there is an action very similar to that which takes
place in filter-beds on a large scale, and that ordinarily few,
if any, bacteria pass through with the water; but, never-
theless, the risk should not be taken, if, at any time, there
is danger of incurring disease.
Filters in which the material is cemented up so that it
cannot be removed for cleaning or renewal should not be
used. Sponge, wool, etc., are liable to decompose and
give organic matter to the water, and cannot be thoroughly
cleaned. Asbestos acts only as a mechanical filter, and
may allow albuminous matter and disease germs to pass.
Asbestos-cloth may be used, however, to support the other
filtering media in those filters where the water-supply
enters at the bottom, and it has the advantage that it can be
perfectly sterilized by fire. Small tap filters are insuffi-
cient for the work required of them, and soon clog. Pocket
filters are simply strainers and have little oxidizing power.
They may be quite useful for tourists, hunters, etc., but
should be frequently sterilized by boiling. Ordinarily,
filters should not be placed in rain-water cisterns, but
outside where they may be easily cleaned.
The best filtering media are sand, animal charcoal, mag-
netic carbide of iron, spongy iron, etc. Unglazed porcelain
or bisque, as is used in the Pasteur-Chamberland filter, is
an excellent medium, and is practically germ proof, though
some observers state that bacteria will pass through un-
cleaned filters of this material after five or six days.
Others claim that these are not bacteria, but only the
mycelia of certain budding fungi with no power of repro-
170
MANUAL OF HYGIENE AND SANITATION.
duction. Stone filters may be good and resemble the por-
celain ones in action, but are apt to be slow, and must be
cleansed often.
FIG. 32.
Glass model of Loomis-Manning filter, showing filter in action.
Sharp, clean sand, not too fine, has fair filtering proper-
ties, as it stops most of the suspended matters and bacteria,
WATER.
171
beside oxidizing somewhat the dissolved organic matters.
It makes a good first layer for a filter, because it is cheap
FIG. 33.
Glass model of Loomis-Manning filter, showing material during cleansing.
and can be easily renewed or cleaned and sterilized by
boiling. Crushed quartz is of practically the same nature.
172 A MANUAL OF HYGIENE AND SANITATION.
Animal charcoal is, when fresh, an excellent material,
as it removes both suspended and dissolved matters,
organic and inorganic, and even color. It acts both me-
chanically and chemically, and with a good volume of it
water may pass through rapidly and be well purified.
But after a time it ceases to be effective, and water must
not be left in contact with it long, as it will give up
organic matter to the water again, and also phosphate of
lime, the latter especially favoring the development of
micro-organisms. Moreover, fresh organic matters, and
possibly bacteria are said to pass through it readily, though
dead or decomposing matter is rapidly destroyed. It
should be changed or cleansed, even when in sufficient
bulk, three or four times a year; oftener if the water to
be filtered is very bad. It is more efficacious than any
other substance in removing lead from water.
Magnetic carbide of iron is one of the best filtering
materials, as it has considerable power in oxidizing organic
matters, converting them into nitrates and nitrites, the
action being greater the longer the water is in contact with
it. It acts partly by surface condensation of oxygen;
partly, perhaps, by electrolytic action. If sand be used
as a first layer to remove solid matters, so that the water
reaches the carbide perfectly clear, and if the sand be fre-
quently renewed or cleansed, the carbide need never be
changed; but the filtration must be intermittent, so that
the carbide may be frequently aerated. Spongy iron has
an action very similar to that of the magnetic carbide on
organic matter, and, like it, the action is the greater the
longer the contact. It must be kept covered with water
to prevent rusting and caking, and should be renewed
about once a year. The small amount of iron that the
magnetic carbide and spongy iron give to the water may be
WATER. 173
removed by passing it through a layer of pyrolusite, a crude
oxide of manganese. A mixture of pyrolusite and sand,
or crushed quartz, makes an excellent filtering material.
Ice should not be added to filtered or drinking-water,
as freezing, even for a long time, may not kill certain
disease germs. Prudden has kept typhoid bacilli frozen
in ice for over three months without destroying their
power of growth and reproduction when brought to a
suitable temperature. The same objections do not, of
course, pertain to artificial ice carefully made from dis-
tilled-water as to that from polluted ponds or rivers; but
it is well to cool the water by placing it in stoppered bottles
upon ice or in vessels surrounded by ice, rather than by
adding ice to the water directly.
The examination of a drinking-water should have regard
to its physical, bacteriological, and chemical properties, as
well as to a consideration of all the circumstances affecting
its source, storage, and distribution. Consequently, a
decision on the purity of a water should be governed by
all the circumstances available: whether it is well-,
spring-, rain-, or river-water; whether it has been at any
time exposed to pollution; in what kind of a cistern or
reservoir it has been stored, etc.
A physical examination of water considers the color,
clearness, sediment, lustre, taste, and smell. Pure water
has a bluish tint, but most waters are grayish, greenish,
yellow, or brown. Yellow or brown waters are suspi-
cious, as the color may be due to animal matter or sewage,
though vegetable matters or iron may give the same color.
Green waters are usually harmless, the color being due to
vegetable matters. The color is judged by allowing the
sediment to settle and pouring off the supernatant water
into a tall glass vessel or tube to the depth of about
174 A MANUAL OF HYGIENE AND SANITATION.
twenty-four inches; the color is then compared with a
similar depth of distilled water, looking down through
both upon a white surface, or, after sealing the tops of the
tubes with glass plates, by looking through each in turn
at a white light.
The clearness of a water is to be estimated in the same
way as above, except that the sediment is to be shaken up
with the water. The depth needed to obscure print may be
used as an index. Where the solid matter will not settle,
owing to the minuteness and lightness of the particles, one
should determine whether the use of a coagulant and filtra-
tion is indicated, or whether boiling will tend to precipitate
the sediment. The sediment may be roughly judged by the
eye as to whether it is mineral or otherwise; it should also
be examined microscopically, for which purpose it may be
collected by using a centrifugal apparatus or by allowing
it to settle from the water in a conical glass, and then
removing it to the slide with a pipette. Mineral matters
are recognized by their crystalline or amorphous struc-
ture or by micro-chemical tests; vegetable cells, portions
of leaves, etc., by their structure and the presence of
chlorophyll; animal substances, as hair, wool, epithe-
lial and other cells, by their peculiar characteristics.
Dark brown, globular masses may come from sewage.
Anything indicating that water has come from human
habitation renders it suspicious, as it may contain sewage or
other polluting substances. Some of the larger animalculae
and sometimes iron may be detected with the naked eye.1
The lustre is supposed to indicate the amount of aera-
tion; it may be nil, dull, vitreous, or adamantine. It
should not be forgotten that a very impure water may be
clear, bright, and sparkling.
1 See J. C. MacDonald's Guide to Microscopic Examination of Drinking-water.
WATER. 175
Any badly tasting water should be considered suspicious.
Dissolved animal matters may be tasteless, but suspended
substances give a peculiar taste, whether animal or vegeta-
ble. Iron is about the only ordinary mineral that can be
tasted in small quantities. Good water depends for its taste
mainly upon its gases, and water free from gas tastes flat.
The smell of a water, if it has any, may be brought out
by heating gently to about 110° F., or by boiling it.
This may make evident a fecal odor, although sulphu-
retted hydrogen may mask this latter; in such a case the
sulphuretted hydrogen may be removed by adding a little
copper sulphate to the water. The odor may also be devel-
oped by allowing the water to stand in a corked bottle in
a warm place for a few days.
A bacteriological analysis is almost as necessary as a
chemical one, for purity in the one respect does not neces-
sarily indicate purity in the other. The presence of the
bacterium coli communis in a water, irrespective of any
pathogenic organisms, would create a suspicion of con-
tamination by fecal matter, as this microbe is practically
a constant occupant of the human intestinal tract.
Water may be collected for bacteriological analysis in
sterilized, closed bulbs blown from glass tubing. The
heat used in sealing the ends creates a partial vacuum
within the bulb, so that if the tip of one end be broken
off beneath the surface of the water, the latter is drawn
up into the bulb, which can then be resealed and conveyed
to the laboratory. But it is always best, if possible, to
inoculate the culture-media at the place where the supply
for examination is obtained, as the bacteria multiply rap-
idly in transportation, and some species may even destroy
others. This can be done by adding a small quantity of
water to melted nutrient gelatine and making plate cultures
176 A MANUAL OF HYGIENE AND SANITATION.
in the manner already described. The number of colonies
resulting therefrom will indicate practically the number
of bacteria in the quantity of water added to the gelatine.
The details of the tests and methods employed in the
chemical analysis of drinking-water will be given . in
another chapter. Here we need only consider the influ-
ence that the substances sought for in the analysis have in
affecting potability and within what limits we may con-
sider them as being permissible in drinking-water. The
water should be filtered or free from sediment for all the
tests, except in the estimation of nitrogen as ammonia
compounds and as organic matter, and of the oxygen-
consuming power of the water.
The amount of total solids will vary with the source of
the water, and much more might be present in some cases
than would be safe in others; but usually the proportion
should not exceed 50 or 60 parts in 100,000. Only a
small portion should be volatile, and there should be little
charring or ignition, except in the case of waters from
peaty soils; nor should there be any odor on ignition, espe-
cially of ammonia compounds, as that would indicate an
excess of animal organic matter. Deep well-water will
probably have much more total solids than rain- or river-
water, the excess being mainly mineral substances dis-
solved from the strata through which the water passes.
Even the purest waters contain a little chlorine, usually
in the form of sodium chloride; but as the latter is a con-
stant constituent of household slops and sewage in gen-
eral, any excess of chlorine above the amount common to
the water of the district, unless otherwise accounted for,
will be decidedly suspicious, and sewage contamination
should be looked for. So, also, any sudden increase in
the proportion of chlorine would very likely indicate the
WATER. 177
accession of some new supply of contamination to the water.
Unless accounted for by the strata traversed, more than three
parts of chlorine in 100,000 of water is very suspicious.
The presence of considerable "free ammonia " in rain-
water is not a bad sign, as it has probably been absorbed
from the air; but the same amount in subsoil- water,
especially if with an excess of chlorine, would indicate
probable contamination with urine, as this latter rapidly
undergoes ammoniacal putrefaction. In such a case there
will probably also be considerable " albuminoid ammo-
nia/7 but much albuminoid ammonia with little free
ammonia and chlorine generally indicates vegetable con-
tamination. The writer is acquainted with a case in
which the albuminoid ammonia and chlorine are in marked
excess, the former being altogether of vegetable origin —
from a peaty soil — and the latter characteristic of the
whole district. The free ammonia is, however, slight in
amount. An excess of free ammonia, chlorine, nitrates and
nitrites indicate animal contamination, though, if the pol-
lution be by effluvia alone, there may be no excess of
chlorine.1 The total ammonia in a usable water should
not be over 0.13 or 0.15 parts per 1,000,000. If there
is almost no "free" ammonia, the "albuminoid" may
amount to 0,10 parts per 1,000,000 without giving cause
for suspicion; likewise, if there is but little "albumi-
noid," there may be considerable "free" ammonia; but
if the " albuminoid" exceeds 0.5 parts per 1,000,000, the
"free" must not be greater than this proportion. The
simplest test for ammonia is by means of Nessler's reagent,
a solution of a double iodide of potassium and mercury.
It gives a yellow or yellowish-brown coloration when am-
monia is present.
1 Kenwood's Hygienic Laboratory, p. 49.
12
178-4 MANUAL OF HYGIENE AND SANITATION.
Organic matters of animal origin, and, therefore, nitro-
genous, are, during oxidation, converted partially into
ammonium compounds, and these, by the action of certain
bacteria, may be further oxidized into nitrites and nitrates.
" 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. 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 con-
tinuous 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 quan-
tity. "l Deep water may, of course, also contain nitrates
taken up from strata rich in these salts.
Although nitrites and nitrates are not at all harmful
in the quantities usually found in water, and though the
water containing them may have been thoroughly purified
by long filtration, their presence, as will be seen from the
above remarks, is important in determining the character
of the water. The presence of the slightest trace of nitrites
is always suspicious, and any marked amount of nitrates,
excepting possibly in a deep water, should require close
investigation; the nitrates and nitrites together measured
in terms of nitrogen should not exceed one part per million.
The hardness should not be greater than that indicated
by 20 or 30 parts of chalk in 100,000, and the more
u temporary" in proportion to the " permanent" hard-
ness the better.
Phosphates, not from phosphatic strata, help to indicate
sewage contamination. So, also, do sulphates, though
these by themselves may come from harmless sources.
1 Leffmann and Bevam : " Examination of Water," 2d edition, p. 13.
WATER.
179
It will be seen from the above that the opinion regard-
ing any water must be based on a broad consideration of
all the circumstances in connection with it, and not from
the presence or absence in it of any one or two substances,
which are not in themselves harmful. The presence of
poisonous metals above the limits of safety would, however,
alone contraindicate the use of a water. For instance, there
should not be more than one-twentieth of a grain of lead
or copper, one-fourth grain of zinc, or one-half grain of iron
in any water, and the faintest trace of arsenic condemns it.
The following table has been adapted from Parkes :
PROPERTIES.
Class.
Physical.
Microscopical.
Chemical
(Parts per 100,000).
I.
Colorless or bluish
Mineral matter ;
Chlorine under 1.4
Pure
tint ; transparent, i vegetable eiido-
Total solids under 7.14
water.
sparkling, and well l chrome; large ani- Ammonia under 0.007
aerated; no sediment mal forms ; no or- | Nitrogen, as nitrites
visible ; no smell ; ganic debris. \ & nitrates, under 0.023
taste palatable. Total hardness 8.5
II.
Colorless or slight
Same as for pure Chlorine under 4.3
Usable
greenish tint; trans- water. Total solids " 42.8
water.
parent, sparkling,
Ammonia under 0.015
and well aerated; no
Nitrogen, as nitrites
suspended matter,
& nitrates under 0.125
or easily separated
Total hardness 17.3
by coarse filtration
or subsidence ; no
smell ; taste palata-
ble.
III.
Suspicious
Yellow or strong Vegetable and ani-
green color ; turbid ; mal forms, more or
Chlorine 4 to 7
Total solids 43 to 71
water. considerable sus- less pale 'or color- Ammonia 0.015 to 0.023
peuded matter ; no less ; organic debris; Nitrogen, as nitrites
smell ; but any fibres of clothing or and nitrates
marked taste. other house refuse. ! 0.125 to 2.47
Total hardness,
above 17
IV.
Yellow or brown
Bacteria of anv Chlorine above 7.14
Dangerous color; turbid, and ' kiud; fungi; numer- Total solids " 71.4
water. ; not easily purified
ous vegetable or ani- Ammonia above 0.0225
i by coarse filtration ; mal forms of low I Nitrogen, as nitrites
large amount of sus- types ; epithelia or
pended matter ; any other animal struc-
& nitrates, above 0.026
Total hardness,
marked smell or
tures ; evidence of
above 28.5
taste.
sewage or ova of
parasites, etc.
CHAPTER VI.
FOOD.
THE use of food is necessary to build up the body
structure, to repair waste, and to furnish force and energy
for the proper action of all the organs, tissues, and parts of
the body. In addition, certain substances are needed, not
so much because they become a part of the tissue frame-
work or yield kinetic energy directly, as that they are
essential factors in the multitudinous chemical reactions
and changes that are continually occurring within the
living person. We may, accordingly, define a food as
anything that tends to fulfil any one of these functions,
provided it is not at the same time by nature harmful to
the economy and that it does not produce physiological
effects out of all proportion to its nutritive or metabolic
activities.
Strictly speaking, this definition might include air and
water, as the former is necessary to supply oxygen for
union with other foods or with the tissues themselves, in
order to produce the heat and vital energy of the body,
and the latter is needed to assist in the solution and assimi-
lation of food-stuffs, to maintain the fluidity of the body
juices and keep the tissues effectively moistened, to pre-
serve roundness of form, and to flush out and remove from
all parts of the system those waste matters and excremen-
titious substances whose retention gives rise to the symp-
toms of certain autogenetic diseases. But they are not
usually included in the category of foods, and, as we have
FOOD. 181
already considered them at length, they may be passed
over in this connection with but incidental reference here
and there.
If we classify foods according to their chemical com-
position, we may separate them into the followng main
divisions :
1. Proteids and albuminoids. 2. Carbohydrates. 3.
Hydrocarbons or fats, and 4. Salts, extractives, etc. Each
group is subject to different digestive and metabolic pro-
cesses, and each has usually a different office within the
body; for experience and careful experiments both show
that all forms of these different classes of food are needed
to sustain life and maintain health for any considerable
length of time, and that with them nothing else is abso-
lutely necessary; although what are sometimes called the
accessory food-stuffs and many pleasant volatile odors and
flavors are desirable and advisable adjuncts to the food
proper, since they greatly favor its reception, digestion,
and assimilation. But, though each class of food has its
own special function in the economy of nutrition, in times
of need or deprivation any one of the first three divisions
may, in a way, supply the place of either of the other two.
Fothergill1 epitomizes the use of the food-principles in
this way : " The carbohydrates are the body-fuel, the sur-
plusage being stored as fat; the albuminoids (proteids)
serve to repair the tissues as they wear out; the salts form
the blood-salts; the fat helps to bnild up normal health
tissues, the excess being burnt as body-fuel. That is the
real object of food."
While in the main correct, this is a broad statement of
facts, and it needs some qualification. For instance, just
i Manual of Dietetics, p. 5.
182 A MANUAL OF HYGIENE AND SANITATION.
as there is some wear and tear in any mechanical machine
while in use, which must eventually be provided for; so in
the human body with its manifold activities there must be
some destructive effect upon the body structure and tissue
framework, and it is to renew and replace this inevitable
loss of material that a part — perhaps the great part — of the
proteid food is taken. But we now also know that in addi-
tion to this simple repair and replacement of tissue, " the
presence of nitrogenized structure, and its participation in
the action going on there, is a necessary condition for the
manifestation of any vital energy or any chemical change,"
and we must feel that, entirely apart from the idea, of
repair, proteid food is essential to the maintenance of this
chemical and vital activity of nitrogenized tissue.
Confirming this, Pettenkofer and Yoigt have shown
that the absorption of oxygen is largely determined by
the nitrogenous substances composing the tissues of the
body, and that it is proportional to their size and vigor.
Moreover, it is known that proteids may be, in part, con-
verted into fat and possibly into other oxidizable sub-
stances, and thus become a source of body heat and energy.
So also with the fats and carbohydrates. While they
are not immediately nor entirely interconvertible, and
while neither class may be permanently excluded from the
diet, yet in emergency either may apparently fully sup-
plant and substitute the other for a time, and we cannot
yet say exactly how similar or dissimilar their service
within the body is.
However, while FothergilPs epitome needs this emen-
dation, known facts make it comparatively easy to gain a
fair idea of the differences and functions of the proximate
food principles, to which end some help will probably be
given by the following table :
FOOD,
183
! EXAMPLES.
, 1.
FUNCTIONS.
NITROGENOUS SUBSTANCES.
1. Proteids.
All substances containing nitro-
gen of a composition identical
with, or nearly that of albumin :
proportion of N to C being nearly
as 2 to 7, or 4 to 14.
1 (a). Substances containing a
larger proportion of nitrogen are
apparently less nutritious.
Proportion of N to C, about 2 to
5%, or 4 to 11.
(ft). Extractive matters, such as
are contained in the juice of the
flesh.
NON-NITROGENOUS SUBSTANCES.
2. Fats (or Hydrocarbon*).
Substances containing no nitro-
gen, but made up of carbon, hydro-
gen, and oxygen ; the proportion
of oxygen being less than sufficient
to convert all the hydrogens into
water.
Proportion of unoxidized H to
C, about 1 to 7.
3. Carbohydrates.
Substances containing no nitro-
gen, but made up of carbon, hydro-
gen, and oxygen ; the oxygen be-
ing exactly sumcient to convert
all the hydrogen into water.
Proportion of water to carbon,
about 3 to 2.
3 (a). Vegetable acids aiid pectous
substances.
Substances containing no hydro-
gen, but made up of carbon, hydro-
gen, and oxygen ; the oxygen be-
ing generally in greater amount
than is sufficient to convert all the
hydrogen into water.
4. Salts (mineral).
Animal :
Albumin, ; Formation and repair of tis-
Fibrin, sues and fluids of the body.
Syntqnin, i Regulation of the absorption
Myosin, and utilization of oxygen. May
Globulin, also form fat and yield energy
Casein. under special conditions. In
Vegetable : ! most foods the above, both ani-
Glutin, mal and vegetable, are parti-
Legumin. ally converted into peptones.
Gelatin, These perform the above
Ossein, i functions less perfectly, or
Chondrin, ' only under particular circum-
Keratin, stances.
These substances appear es-
sential as regulators of diges-
tion and assimilation, especi-
ally with reference to the gela-
tin group.
Olein, Supply of fatty tissues ; nu
Stearin, trition of nervous system ?
Margariu, Supply of energy, and animal
heat by oxidation.
Starch, Productive of energy and
Dextrin, animal heat by oxidation.
Cane sugar, Conversion into fat by deoxi-
Grape " | dation.
Lactin (or
milk sugar)
( More O than
is sufficient
to convert
all H into
H20).
Oxalic acid,
Tartaric "
Citric
Malic "
(No excess
of O).
Acetic acid,
Lactic "
Sodium
chloride,
Potassium
chloride,
Calcium
phosphate,
Magnesium
phosphate.
Iron, etc.
Preserving the alkalinity of
the blood by conversion into
carbonates ; furnish a small
amount of energy or animal
heat by oxidation.
Various ; support of bony
skeleton, supply for HC1 lor
digestion, etc. Regulators of
! energy and nutrition.
184 A MANUAL OF HYGIENE AND SANITATION.
Dietetics means " a systematic regulation of the diet for
hygienic or therapeutic purposes. " It considers all the
factors that affect the proper digestion and assimilation of
food. For instance, it is not alone necessary to determine
just what substances, in a chemical sense, the body needs
to sustain life and maintain health. Nor is it sufficient
to say that a man must have just so much of this and so
much of that food, for there must always be a variation
in both kind and quantity to meet the changing demands
of the system. With a few exceptions, no matter how
toothsome or healthful a certain food may be, it soon palls
upon the appetite if necessity compels its continued use
for a prolonged period, and this disgust may be so impressed
upon the memory of the senses as to cause them to prevent
the use of that food forever after.
The aesthetic factors in the preparation and serving of
food must also be taken into account, and the question of
pleasing the appetite has much to do with the progress
and completeness of digestion. Other things being equal,
palatable and agreeable foods are disposed of much more
satisfactorily than others not so, and physicians and
others should learn that especially in sickness the appear-
ance and palatability of a food have much to do with its
acceptance, not only by the patient, but by his stomach
as well. Cleanness and neatness in food, china, and
napery are of greater value than expense or show, and a
little attention and tact in such matters will often enable
a patient to take, enjoy, and retain food and nourish-
ment, even when he or she asserts and believes this to be
impossible.
Another factor of much importance in the digestion of
food, but one too often too lightly considered, is the mood
or state of mind when the food is taken and while it
FOOD. 185
remains in the alimentary canal. There is more than
moral philosophy in maintaining a cheerful and a tranquil
disposition during the daily meals and for a time there-
after; while there are numerous instances of most serious
results occurring from the giving way to anger or other
intense emotion at such times, the digestive functions being
either completely checked or, what is frequently worse, so
altered that the products are actually toxic in their char-
acter. And is not a dyspeptic often so because of his
pessimism, rather than a misanthrope because of his indi-
gestion ?
Before proceeding further it will be well to consider
briefly the physiology of digestion in so far as it concerns
the chemical changes occurring in the food while it is in
the digestive tract. These changes are brought about by
the action of certain bodies secreted or made by the diges-
tive organs and glands, which we have been in the habit
of calling unorganized ferments, but which would, perhaps,
better be known hereafter as enzymes. Unorganized fer-
ments were so called because they have not the definite
cell-formation, life, and power of reproduction which be-
long to the yeasts, mould-fungi, and bacteria which bring
about the fermentative changes in organic substances so
commonly within the knowledge of every one, such as the
conversion of saccharine solutions into alcohol, of alcohol
into acetic acid, etc.
The enzymes likewise act ujton organic matter, viz. , upon
the food which we eat, and — like the other ferments — ap-
parently simply by their presence rather than by entering
into actual combination with the matter acted upon, as do
ordinary chemical reagents. They are undoubtedly the
products of glandular protoplasm, probably proteid in
nature, and some, at least, very likely belonging to the
186 ^ MANUAL OF HYGIENE AND SANITATION.
group of nucleo-albumins, which latter form a component
part of every organic cell.
The knowledge of the digestive functions will be greatly
simplified for the student if he remembers that " with the
possible exception of the coagulating enzymes, the action of
the enzymes is that of hydrating agents: they produce
their effect by what is known as hydrolysis — that is, they
cause the molecules of the substance upon which they act
to take up one or more molecules of water; the resulting
molecule then splits or is dissociated, with the formation '
of two or more simpler bodies. "l
Thus the insoluble proteids and carbohydrates become
respectively the soluble peptones and sugars of their allies,
capable of absorption into the myriad capillaries that are
distributed throughout the lining membrane of the alimen-
tary tract; and even the change that takes place in the
fat digested is one that involves the taking up of some
water.
There are four characteristics of the enzymes worthy of
note : 1. That they are all soluble in water and glycerin,
the latter being specially useful in making stable prepara-
tions of them from the organs producing them. 2. f( That
very low temperatures (0° C.) retard or suspend entirely
their action, without, however, destroying the enzyme;
that for each enzyme there is a temperature at which its
action is greater/7 and that " in a moist condition they
are all destroyed by temperatures below the boiling-point;
60° to 80° C. are the limits actually observed.772 3.
" That they never completely destroy the substance upon
which they act,77 probably being retarded by their prod-
ucts when the latter reach a certain percentage. ' ' When
these are removed the action of the enzymes begins again.77
i American Text-Book of Physiology, first edition, p. 219. 2 Ibid.
FOOD. 187
4. " Except for very small quantities, it may be said that
the amount of change caused is independent of the amount
of enzyme present,7' or rather, " with increasing amounts
of enzymes the extent of action also increases, reaching a
maximum with a certain percentage of enzyme; increase
of enzyme beyond this has no effect." The amount of
change capable of being produced by a small amount of
an enzyme is enormous, good pepsin, for instance, having
the power of converting 2500 times its own weight of
proteid; but we must remember that this power is not
infinite, and that after a time all of the enzymes will cease
to act.
There are five groups or classes of enzymes to be found
in the1 animal body concerned with the proper digestion
of food, and it is interesting to note that examples of
each of these classes are also to be found in various mem-
bers of the vegetable world. The two principal remaining
classes, being neither of animal origin nor digestive agents,
need only be mentioned here: They are the glucoside-split-
ting and urea-splitting enzymes, the latter being produced
by certain bacteria and converting urea into ammonium
carbonate.
Considering the digestive processes in their order as the
food proceeds from the mouth through the alimentary
canal, we find that the first active secretion or fluid is the
saliva, and that its enzyme. is ptyalin, belonging to that
group which converts the insoluble carbohydrates (starches)
into soluble sugars, maltose, dextrin, etc. Pytalin acts
best in neutral or slightly alkaline media, at about the
body temperature (40° C.), and upon cooked rather than
raw starch. Its action is retarded or totally checked by a
low temperature or by strongly alkaline or very slightly
acid solutions, and the enzyme itself is actually destroyed
188 A MANUAL OF HYGIENE AND SANITATION.
by a slight increase in acidity or by a temperature of 65°
or 70° C. The reason it converts cooked starch so much
more quickly is probably because the heating process breaks
up the cellulose envelopes that protect the starch granules
within from its action, and upon which the pytalin has
almost no effect.
In addition to its digestive function, the saliva also
serves to moisten dry food so that it may be swallowed,
and to dissolve sapid and savory substances that they may
be duly appreciated by the organs of taste.
Our first hygienic lesson in regard to the digestive
functions is, therefore, that in order to get the full
benefit of the salivary secretions, all food, and especially
that of a starchy nature, should be well masticated and
retained in the mouth for some little time, instead of
its being " bolted" at once or after a hasty bite or
two. Nor should very cold nor very hot beverages be
taken at the same time with the food, for not only will
the action of the pytalin be thus retarded or destroyed,
but that also, as we shall see, of the gastric juice within
the stomach.
The food, having passed from the mouth to the stomach,
may still be acted upon for a few moments by the pytalin
until the latter is checked by the acid of the gastric juice.
The energy of digestive action is then transferred from
the starches to the proteid constituents of the food, the
chief enzyme now being pepsin, though we also find in
the gastric juice a coagulating ferment — rennin, which acts
upon soluble proteids like the casein of milk, to form
insoluble clots or curds.
Pepsin acts only in an acid medium (the acidity being
supplied normally by the free hydrochloric acid of the gas-
tric juice), and best at the body temperature. As stated,
FOOD. 189
extremes of temperature are adverse to its activity, and
may check it altogether, and, likewise, too much or too
little acid may have the same effect, from 0.2 to 0.3 per
cent, of HC1 being the normal amount and giving the
best results. Rennin seems in the normal stomach to act
only on the casein of milk, and curdles this probably
because it is then more easily digested by the pepsin and
by the trypsin of the pancreatic juice.
The action of the pepsin plus the acid upon the proteids
of the food is a hydrolytic one, and the end products are
practically hydrated proteids, substances especially diffusi-
ble and capable of absorption. The gastric digestion, there-
fore, after the ptyalin has been checked by the acid gastric
juice, practically has to do only with the albuminous or
nitrogenous part of the food, the remainder, or at least
that part of it not yet capable of absorption, remaining
unchanged until it passes on further into the intestines.
Soluble salts, sugars, and part, at least, of the peptones as
they are formed, may, however, be taken up by the stom-
ach capillaries, while the rest of the food-mass, kept ever
in motion by the muscular movements of the stomach-
walls, is being thoroughly mixed and converted by the
peptic action into the semi-liquid substance called chyme,
which is passed at intervals and in small quantities through
the pyloric opening into the .duodenum. Long before the
stomach has entirely emptied itself, which may only be
after several hours of activity, intestinal digestion is well
under way, and in some respects this is the most im-
portant as well as the most comprehensive process of all.
The three secretions to whose combined action the chyme
is now subject are the pancreatic juice, the bile, and
the intestinal juice. All are alkaline and quickly neu-
tralize the gastric acid; it scarcely need be noted, then,
190 A MANUAL OF HYGIENE AND SANITATION.
that the remaining enzymes act best or only in alkaline
media, though one of them, trypsin, may act in solutions
not too strongly acid.
In the pancreatic juice we find three enzymes, practically
the only remaining ones of much importance; although in
the rather scanty intestinal juice two others have been
found, one capable of converting starch into sugar, and
the other inverting cane-sugar into levulose and dextrose.
The bile contains no enzymes. The pancreatic ferments
are trypsin, which acts upon proteids and albuminoids
even more powerfully than pepsin, and likewise converts
them into peptones; amylopsin, which is practically iden-
tical in its properties with ptyalin; and steapsm, which
causes neutral fats to take up water and split into free
fatty acids and glycerin. .
Under the action of the trypsin all that portion of the
proteid foods which has not been completely digested in
the stomach reaches that stage in the upper intestines and
is absorbed therefrom. In fact, it is very probable that
the tryptic digestion is often the more important of the
two. As the action of the saliva upon the carbohydrates,
which form the greater bulk of our food, must of necessity
be very limited, it is evident that practically almost all
of the starch digestion is performed by the amylopsin,
aided in slight measure by the similar enzyme of the intes-
tinal juice. The salts and other soluble elements of the
food have already been absorbed, and there remain only
the fats or hydrocarbons.
Under the influence of the steapsin comparatively a
small portion of these is, as stated, separated into glyc-
erin and free fatty acids, and this action for some reason
takes place much more rapidly when aided by the bile
than with the pancreatic juice alone. Then, these fatty
FOOD. 191
acids unite with the alkalies and alkaline salts of the
above secretions, but especially of the bile and intestinal
juice, to form soaps, and these soaps aid in emulsifying the
remainder of the fats and thus making them ready for
absorption, which latter process is also facilitated by the
direct action of the bile upon the intestinal epithelium.
The digestive processes having been thus outlined, it
will be well to learn how they may be maintained as com-
plete and perfect as possible. In the first place, the cook-
ing of food is usually an essential preliminary. We cook
meats not only to make them more agreeable to the palate,
but also to facilitate digestion. The effect of cooking upon
muscle (flesh) is " to loosen the bundles of fibrillae from
each other, so that they are readily torn asunder or crushed
by the teeth," while the various connective tissues are
softened and gelatinized, not only thus becoming more
digestible and nutritious, but allowing the histologic ele-
ments which they bind together to separate and be more
freely acted upon by the solvent fluids. So with the
vegetables, the heat and steam soften and rupture the
cellulose envelopes of the various cells that the ferments
may the more readily act upon their contents; and at the
same time they bring about subtle chemical changes that
greatly increase the palatability of the food-stuffs.
Thorough mastication of the food is important for the
reasons already stated, and the cause of most dyspepsias
may be found in faulty habits of eating. Foster says that
in the stomach " the natural bundles of meat and vegeta-
bles fall asunder, the muscular fibres split up into disks,
and the protoplasm is dissolved from the vegetable cells ;"
but, " if the meat be not chewed properly, but ' bolted/
the solvent gastric juice can only act on the exterior of the
mass, while l lumps ' offend the stomach and arrest the
192 ^ MANUAL OF HYGIENE AND SANITATION.
gastric secretion." The importance of abstaining at meal-
time from beverages or other substances of too low or too
high a temperature has already been stated, and, as ail the
enzymes act best at the body temperature, care should
always be had to avoid the chilling of the abdominal
organs while digestion is under way.
Again, as the formation and action of the enzymes begin
with the ingestion of food and depend largely upon a
sufficient blood-supply to the organs concerned as long as
digestion continues, it is essential that the blood-current
shall not be diverted from these organs during this period
by excessive mental or physical demands, and that a con-
dition of cheerfulness, repose, and rest should wisely follow
every meal. Regularity as to the time of meals and the
avoidance of too great a tax upon any of the organs by
over-indulgence or intemperance in eating are likewise
both important matters and ones too often neglected.
It is interesting to note that in certain members of the
vegetable kingdom are to be found enzymes very similar
to those just considered, and that where the latter appear
to be deficient in quantity or action, these kindred ones
may be used with advantage. Thus, in the pineapple
and in the papaw are ferments akin to pepsin or trypsin,
and in the former another with the same action as rennin.
All are familiar with the diastase of germinating seeds
and its use in the making of beer, but not so common
is the knowledge that other seeds contain fat-splitting
enzymes much like steapsin.
The Amount of Food Necessary to Life and Health.
Considerable work has been done to determine just what
amount of the proximate food principles the average per-
son requires daily, and in this respect Moleschott's tables
are quite generally, accepted, having been constructed from
FOOD. 193
data gained by actual experiment and also by the con-
tinued observation of the effects of a number of dietaries.
According to these tables, a man weighing 160 pounds
and doing work equivalent to 300 foot-tons per diem will
need about 4.6 ounces of proteids, 3 ounces of fats, 14.25
ounces of carbohydrates, and a little more than 1 ounce of
salts. Prof. Yaughan believes that the average working
man in America requires daily, in round numbers, not
less than four ounces of proteids, two ounces of fats, and
eighteen ounces of carbohydrates.
It is essential that the proper proportion between the
ingested nitrogen and carbon should be maintained, and
this should be as one of the former to fifteen of the latter.
In addition, the individual needs from 70 to 100 fluid-
ounces of water daily, a good part of which, however, is
normally taken with the food. It must be remembered
that the above figures only represent average amounts, and
that climate, amount of exercise, the size and activity of
functional and excretory organs, and personal peculiarities
all serve to modify them in the case of any special indi-
vidual.
Other conditions not interfering too greatly, any combi-
nation of foods giving the above amounts of the proximate
principles at a reasonable cost will be an economical
and healthy diet, provided such food is acceptable to the
palate, is digestible, and contains nothing harmful to the
system.1
Fothergill thinks that, as a rule, we take too much pro-
teid food, especially in the form of meat, and that, though
this goes in the main for tissue repair, the latter requires
1 For such combinations, see Vaughan's Healthy Homes and Foods for the
Working Classes, and Mrs. Abel's Practical, Sanitary, and Economic Cooking.
Both are essays published by the American Public Health Association.
13
194-4 MANUAL OF HYGIENE AND SANITATION.
much less of such food than we ordinarily suppose, and
that the system does not need so very much of albumin or
its equivalents. In this he may be correct to a certain
degree, particularly as regards his fellow-Englishmen,
who are notorious meat eaters, and as to the facts that
tissue waste is comparatively slight, and that the body
framework rusts out rather than burns out. But in addi-
tion to the statements already made— »- that part of our nitro-
genous food regulates the demand for oxygen and that
part is doubtless a source of energy and may be converted
into fat — we should also remember that animal food is a
concentrated food, that much energy has been expended in
converting and storing it up from the vegetable world,
that it is stimulating, and that our digestive organs resem-
ble more closely, at least as far as comparative weight is
concerned, those of the carnivora rather than of the herbiv-
ora. These reasons, as well as the fact that proteids make
up a considerable part of the only typically complete food
that we have and which nature gives to the mammalian
infant, indicate that we should be as careful not to use too
little as too much nitrogenous food.
The proteid portion of our food is obtained from the
albumin of meat and fish, from milk and eggs, and from
the gluten of cereals and the vegetable casein (albumin)
of the leguminous plants, such as peas, beans, etc. The
proportion and properties of the albuminous matter vary,
of course, in each of these, and even in the same substances
under different circumstances; but all should be taken into
consideration and used interchangeably, if we wish to
obtain the greatest variety and benefit in feeding, together
with due economy of expense.
In this connection attention may be directed to the
peculiar fact that the leguminous plants, through the aid
FOOD. 195
of certain species of bacteria, are able to absorb and store
up in the form of proteids a considerable quantity of
nitrogen from the surrounding atmosphere.
The carbohydrates that furnish food to the body and are
one of the sources of the heat and energy upon which mus-
cular motion and vital activity depend, are practically all
derived, with the exception of milk sugar, from the
starches, sugars, and gums of the vegetable kingdom.
It has already been shown that much the greater part
of the digestion of carbohydrate food is due to the action
of the pancreatic enzyme — amylopsin, but we should not
forget the action of the saliva, nor that thorough mastica-
tion greatly assists the subsequent digestion by breaking
up the starch granules and exposing them more freely to
the action of the digestive juices. The latter object is also
obtained by crushing the cereals, and by cooking the
starch-bearing foods, for " grinding and cooking lessen
the labor of the jaws and salivary (and pancreatic) glands."
After the end-products (dextrose, levulose, etc.) of car-
bohydrate digestion have been absorbed from the alimen-
tary canal, part of them, at least, are reconverted in the
liver into animal starch or glycogen, and this portion
becomes a part of the body-store of fuel. Fothergill says :
" The liver stores up from each meal so much glycogen
and gives it off as required; otherwise life would only be
one dreary meal." Another and perhaps greater moiety
of the digested carbohydrates is converted into fat and
stored away as adipose tissue in various parts of the body,
a further reserve of fuel for any emergency. (t Many
authorities state that fat is formed directly from carbohy-
drates, and the weight of evidence appears to favor this
view; but whether it is so formed directly, or indirectly
by retarding the metabolism of the fatty and proteid con-
196 A MANUAL GF HYGIENE AND SANITATION.
stituents of the food, there is no doubt that the consump-
tion of carbohydrates results in the formation of fat within
the body." Moreover, "whatever the mixture of fats
taken in as food, the fat of the body always has the same
composition; this fact agrees with the conclusion that the
metabolism and deposition of fat in the body is due to cell
activity, and that the fat comes in part from the proteid
and part from the carbohydrate foods."2
Another important function of the carbohydrate foods
is the formation by their metabolism in the body of lactic
and other acids, which are of the greatest value in nutri-
tion and in maintaining the normal reactions of the body-
fluids. This is perhaps one of the chief reasons why fats
and carbohydrates are not interconvertible in any pro-
longed dietary.
Fat is essentially a compound of glycerin with one or
more fatty acids, usually stearic, palmitic, and oleic. The
digestibility of a fat largely depends upon its being fluid
at the body temperature; therefore, the more stearine,
whose melting-point is higher than this, a fat contains, the
less digestible it will be. For this reason butter is more
digestible than suet, lard than mutton fat, etc., and the
more easily assimilable cod-liver oil is that from which
the stearine has been removed.
Fat for food is derived from vegetable as well as animal
sources, many seeds and nuts and some cereals, as oats and
corn (maize), containing much fat. By improved methods
it is becoming possible to supply fats in purer, cheaper,
and more agreeable forms, so that they can now be freely
used even by the poor, the very class that needs them most.
Under normal conditions it is probable that the body-fat
1 Notter and Firth : Treatise on Hygiene, p. 254. - Ibid., p. 253.
FOOD. 197
or adipose tissue is almost never derived from the fat in
food, but rather, as stated, from the proteids and carbohy-
drates. But fat is also an essential part of tissue-struc-
ture, making up more than one-fifth of the solid matter of
the brain and one-sixth of muscle, and possibly serving
as fuel when the tissue is oxidized; and it is not impossible
that this tissue fat may come in part from that ingested as
food. The writer has already hinted at the possibility of
a combination of the newly absorbed fat with the argon
of the atmosphere in the lungs, and the consequent forma-
tion of new cells or vital material. In any case, how-
ever, fat is a very necessary part of a man's diet, for not
only is a small quantity necessary to the digestion of pro-
teids, causing the formation in the body of larger amounts
of fat than the quantity ingested and greatly improving
the physical condition; but it may be, and undoubtedly
often is, used directly as fuel when occasion requires
without first being stored up in the tissues. As it is a
concentrated fuel-food, it is to be used freely when we
want to keep the body warm or when we need extra force
for any increased exertion.
" On a diet rich in fat great muscular effort can be
undergone with but little destruction of muscular tissue,
and without increased urea discharge." The object of fat
in the diet, then, may be said to be as fuel to give heat
and energy, and, when necessary, to aid in the repair or
building up of active tissue.
The constructive property of fat is especially valuable
in the treatment of all wasting diseases, especially phthisis.
Fothergill emphatically declares that l ' the great food for
the strumous is fat," and also says: "Whenever there
is any tendency to tubercle the individual should learn
to eat fat, just as a seafaring man learns to swim. As a
198 A MANUAL OF HYGIENE AND SANITATION.
physician to a chest hospital I have learned to dread the
announcement that fat is no longer taken, especially if the
individual is of strumous build, with a small, narrow
chest. In my opinion, the existence of a considerable area
of affected lung where the digestive powers keep up is less
fraught with evil and less prognostically significant than
intractable wasting with very little disease in the lung."
In this connection, note that an excess of proteids in the
diet causes a more rapid oxidation of fat, and that an
excess of fat or of carbohydrates lessens the absorption of
oxygen and the oxidation of both fats and proteids. Also,
that the free use of fluids is thought to favor an increase
in the quantity of fat deposited in the body.
Fat is practically indigestible in the stomach, and some
stomachs cannot tolerate it, especially when taken with
other food ; although usually a little fat assists in the diges-
tion of proteids by stimulating the secretion of the gastric
juice. Cases occur not rarely in which it is necessary that
comparatively large quantities of fat should be ingested
and yet in which there is apparently decided gastric intol-
erance of it. In such event success is often to be attained
by giving the fat some little time after the regular meals,
when the gastric digestion is approaching completion and
the chyme is being passed out of the stomach to be further
subjected to the action of the intestinal digestants. It
may also be well to emulsify it partially or wholly, espe-
cially if there be faulty secretion of bile and pancreatic
juice, and sometimes to disguise its taste with agreeable
flavors. In this way there is generally but little trouble
in administering fats, even such as those which, like cod-
liver oil, have a disagreeable taste and odor. Failing in
this, we may still resort to inunctions, preferably of pre-
digested or emulsified fats, and often with considerable
FOOD. 199
advantage, since it has been experimentally shown that
after passing through the skin fat may be taken up by the
subcutaneous lymphatics and later be oxidized or meta-
bolized almost as completely as if it had entered the
system by way of the intestinal canal and thoracic duct.
Certain salts in certain proportions are necessary for
the maintenance of health in the body. " Lime, chiefly
in the form of phosphate, is absent from no tissue, and
there is reason to think that no cell-growth can go on
without it." Even the bacteria must have earthy phos-
phates for the purposes of growth. Chlorine, derived
largely from the sodium chloride of food, is necessary to
form the hydrochloric acid of the gastric juice, the chlo-
rides also keeping in solution the globulins of the blood
and body fluids and helping to dissolve the albumin.
Phosphorus is necessary in the formation of the lecithin
of nerve tissues, as well as for the phosphates above men-
tioned, and those of potassium, magnesium, etc., which go
to form bone. Potash salts maintain the alkalinity of the
solid tissues, and soda salts that of the body fluids. Iron
is essential for the construction and nutrition of the blood-
corpuscles, though small quantities of it are to be found
in almost every other tissue.
But not only must the above inorganic salts be given in
proper supply, but also certain ones of organic nature, in
order to prevent conditions of malnutrition or disease.
Those especially which are changed to form carbonates, as
the lactates, tartrates, etc., or their respective acids, help to
maintain the alkalinity of the system and appear to be
most essential, as a scorbutic condition seems to be inevi-
tably created or fostered by their absence. There is also
some evidence that certain gouty conditions may be due
to the removal of the natural vegetable salts by unwise
200 A MANUAL OF HYGIENE AND SANITATION.
methods of cooking. The fact of the carbohydrates being
an important source of these organic acids and salts has
already been mentioned.
Lastly, with many of our foods we require the addition
of certain flavors, condiments, etc., which, though they
have little or no real food value in themselves in the sense
of repairing tissue or furnishing energy, do much good,
when not abused, by making the food more palatable, by
stimulating the secretion of the digestive fluids, and by
acting as carminatives. These condiments should not be
omitted from the food of the sick or convalescent, for they
have a value of their own, and are il agreeable to the palate
and, in moderation, good for the digestive organs/'
As a review of the preceding statements, the following
quotation, from Notter and Firth,1 may be of value :
" With regard to the necessity for all four classes of
aliments, it can be affirmed with certainty that (putting
scurvy out of the question) men can live for some time
and can be healthy with a diet of proteids, fats, salts, and
water. But special conditions of life, such as great exer-
cise or exposure to very low temperature, appear to be
necessary, and Under usual conditions of life health is not
very perfectly maintained on such a diet. It has not yet
been shown that men can live in good health on proteids,
carbohydrates, salts, and water, etc., without fat.
" The exact effect produced by the deprivation of any one
of these classes is not yet known. An excess of the pro-
teids causes a more rapid oxidation of fat, while an excess
of fat lessens the absorption of oxygen, and hinders the
metamorphosis of both fat and albuminous tissues. The
carbohydrates have the same effect when in excess, and
appear to lessen the oxidation of the two other classes.
1 Treatise ou Hygiene, p. 256.
FOOD. 201
u It is generally admitted that the success of Banting's
treatment of obesity is owing to two actions : the increased
oxidizing effect on fat consequent on the increase of meat
(especially if exercise be combined), and the lessened
interference with the oxidation of fat consequent on the
deprivation of starches.
" Health cannot be maintained on proteids, salts, and
water alone; but, on the other hand, it cannot be main-
tained without them/'
It will be impossible to go into details concerning all
the articles commonly used as foods, but there are certain
facts that should be well known and which cannot prop-
erly be omitted from a work of this kind.
Milk is a typical food-stuff, complete in itself, in that it
contains all the food principles, and these in nearly the
proper proportion, at least for infant life. The casein and
albumin represent the proteids; the cream, the fats; and the
lactose or milk-sugar is a concentrated carbohydrate — all
being in combination with sufficient salts and water.
It should constitute almost the sole food of infants during
the earlier months of life; and that it is capable of sustain-
ing adult life almost indefinitely, especially where there is
little demand for heat or the expenditure of force, has been
shown in numerous instances. • Coplin and Bevan mention
the case of a patient who lived and thrived on milk alone
for over thirteen months, and of another who lived for
three years on the same diet. But, of course, the limited
proportion of carbohydrates, even though concentrated, is
not all-sufficient for the maintenance of great vital activity,
and for persons in ordinary life some addition to the diet
is necessary.
The albumin of milk is coagulated by heat, but the
casein, which constitutes the greater part of the proteid
202 A MANUAL OF HYGIENE AND SANITATION.
element, is clotted by an acid or by an enzyme, such as
rennin ; and as both of these are present in normal gastric
juice, it would seem that the preliminary coagulation of
casein was essential to its proper digestion. It should be
remembered, however, that the casein of cow's milk forms
a much harder and firmer clot than does that of human
milk, and that the former should, therefore, never be
introduced into the stomach in large volumes, but should
rather be taken slowly and preferably with other food
which will help to divide the curd mechanically. In the
feeding of children an alkali, such as lime-water, mixed
with the milk is thought to soften the curd and possibly
facilitate digestion.
Outside of the body, fermentative changes due to certain
bacteria may convert the milk-sugar into lactic acid, which
coagulates the casein and (( sours " the milk. Another
peculiarity of casein is the tenacity with which it holds
large quantities of phosphate of lime, one of the most
valuable of food-salts.
Sometimes it is advantageous or necessary to predigest
milk for infants or sick persons, but if the digestion be
carried beyond a certain point, the consequent peptones
and albumoses will give the milk a bitter and disagreeable
taste. In the feeding of infants it must not be forgotten
that the percentage composition of human milk is different
from that of cow's milk, and that the latter will need dilu-
tion to decrease the proteid proportion, but an increase of
fat and carbohydrates. As a child grows older and more
active, it becomes necessary to add to the milk additional
carbohydrates. These should be easy of digestion and
soluble, milk-sugar and predigested starches in the form
of maltose an,d its allies being preferable.
Milk should always be kept as cool as possible and in
FOOD. 203
closed vessels, not only to prevent the absorption of dis-
agreeable odors and harmful gases, to which it is very
prone, but to exclude dirt and bacteria. As it is an excel-
lent culture medium, and as it is commonly liable to be
exposed to contamination by organisms from many sources
before it reaches the consumer, fermentative or other
harmful chemical changes are almost certain to occur in
it if the temperature conditions are at all favorable. For
this reason, it is necessary that the greatest care should be
used in the handling of the milk from the time it leaves
the cow until it is used, and for the feeding of children
and whenever there is any possibility of it being the car-
rier of disease germs of any kind, it should be properly
sterilized and then kept sterile until used. In fact, steril-
ized milk, modified to resemble the human secretion, will
usually be superior to any other artificial food for infants,
but the sterilization should always be done before fermenta-
tion has begun and harmful products have been developed
in the milk. The sterilization may slightly alter the taste
and other properties of the milk by coagulating the albu-
min, bat it is doubtful whether it makes any real change
in its digestibility.
The cream of milk is fat in its most digestible and
acceptable form, and should not be removed from milk if
the latter is to be used as food. If the milk seems to be
too rich, it may be advisable to skim it, giving it in some
form or other with the regular meal and reserving the
cream until a couple of hours or so later, when gastric
digestion is approaching completion. One may also often
escape the use of cod-liver oil and similar fats by taking
cream in this way — either plain or flavored and whipped
— some little time after the meals.
Skimmed milk and buttermilk may be used freely as
204 A MANUAL OF HYGIENE AND SANITATION.
beverages, as both are refreshing and healthful, with some
food value; buttermilk is also very acceptable to many
persons on account of its lactic acid. " Koumiss " and
" kefir " are both prepared from milk through the action
of certain fermentative organisms, which also bring about
a partial digestion of the casein. Each contains carbonic
and lactic acids, though in different proportions, some pep-
tones or albumoses, and a little alcohol. They are agree-
able to most palates and are usually retained and utilized
by stomachs rebellious to almost all other foods.
Milk may be a factor in the causation of disease in a
number of ways. The products of the fermentative action
already referred to are a frequent source of serious intes-
tinal disorders in infants and even in adults; while if
further decomposition occurs, a very poisonous ptomaine,
called tyrotoxicon, is apt to be developed and to cause
even fatal results to those using the milk. This same
substance is also liable to occur in any milk-product, such
as cheese or ice-cream, and is usually the cause or agent
in the cases of poisoning by such products that are so
frequently reported.
Again, the active principles of plants which the cow has
eaten may be transmitted by the milk and produce their
physiological effects. But a graver question is whether
disease may be transmitted directly from the animals to
man by this almost universal food-stuff. Every one knows
that the milk from sick cows may cause marked disturb-
ance of health, and there now seems to be fair evidence
that cattle are subject to certain diseases identical with or
very similar to human maladies, the milk serving as a
carrier for the contagium.
Scarlet fever and diphtheria may be mentioned as dis-
eases suspected of being transmitted in this way, and there
FOOD. * 205
is no longer any doubt in regard to tuberculosis. Though
some authorities still question whether this disease can be
thus transmitted unless the milk-glands themselves are
affected, the great prevalence of the disease among cattle
and experimental evidence both make it certain that milk
is often tuberculous, and many believe that by far the
larger number of the many cases of infantile tuberculosis
have origin from this source.
Milk may also become a disease carrier through care-
lessness in handling by infected persons or by the admix-
ture with it of water containing disease germs. Epidemics
of diphtheria, scarlet fever, typhoid fever, and cholera
have all been traced to a contaminated milk-supply, and
it is a question whether many of the more or less local
outbreaks in cities are not of this character. The writer
is personally cognizant of five cases of undoubted scarlet
fever that occurred almost simultaneously in one locality
and in which, apparently, the only common source was the
milk-supply. He was unable to discover that there had
been any illness either among the cattle or in the family of
the milkman in question, but he has always felt that there
was considerable evasion in replying to the inquiries made.
The possibility of milk as a source of danger to health
having been shown, the lessons to be had are these: that
not only must there be the greatest care in the handling
and keeping of milk until it is consumed, but there must
also be frequent and careful inspection of the animals
from which it comes and of their environment; that no
milk from any diseased cow should ever be used as food;
that wherever there is the suspicion or possibility of the
milk being contaminated with disease germs, it must be
thoroughly sterilized, and that any change from its normal
condition should also forbid its use.
206 A MANUAL OF HYGIENE AND SANITATION.
Fortunately, good milk can almost always be had so
cheaply and readily that no serious hardship inures in the
strict observance of these rules, and the public should be
educated to demand as well as fairly to pay for pure milk
from healthy animals, these matters being even more im-
portant than that the quality, as shown by analysis, should
always be up to a certain standard.
Good milk in balk should be opaque, of clean ivory-
white color, should have no peculiar smell or taste nor
any deposit on standing. Nor should it show any change
in taste or appearance upon boiling, excepting the forma-
tion of the slight skin of coagulated albumin due to the
heating. Details regarding the composition of milk and
the methods for its examination will be found in the final
chapter of this volume.
Cheese is a most valuable food-stuff, and, as a milk
product, should be considered at this time. Good cheese
usually contains twice as much nitrogen and three times
as much fat as the same weight of meat, but many persons
apparently find it difficult of digestion and can eat but
little of it. This is perhaps because the nutriment is so
concentrated and because, as usually eaten, it forms a
pasty, solid mass in the stomach into which the gastric
secretion cannot penetrate. Mattieu Williams has re-
marked that we habitually use cheese in the conditions in
which it is most indigestible — either in its raw state or
cooked into a leathery mass; and he asserts that if the
cooking is such that it is thoroughly mixed with other
articles of food, or if we will masticate it with other food,
so that this commingling of particles takes place, it will
be found to be quite digestible by almost every one. He
also advises the addition of a small amount of potassium
carbonate in the cooking, as this favors the solution of the
FOOD. 207
casein and replaces that salt removed in the whey. It
goes without saying that, as a food, only cheese made from
whole milk, or from that to which extra cream has been
added, satisfies all requirements, and that skim-milk
cheeses are decidedly less nutritious than those having the
full proportion of fat.
Butter, consisting as it does largely of the fat of milk,
is a highly nutritious article of food and one of the most
digestible of its class. It should be pure, sweet, and free
from rancidity, and while some of the substitutes offered
in its stead are entirely wholesome, they should never be
sold as butter or used to adulterate it. Neither should
butter contain an excess of water, nor of casein, as its food
value is thereby accordingly lessened.
Eggs yield almost their full weight of food in a concen-
trated and very digestible condition, and are valuable on
this account, as well as for their palatability and their
value in the preparation of many dishes. Containing
practically no carbohydrates, they have sufficient food
material in themselves for the complete development of
the living chick with the aid of nothing external except
the oxygen which passes through the shell : the lack of
the carbohydrate element, one of the essential food princi-
ples ordinarily, is supplied by the heat from the mother
hen or incubator, which is sufficient for the development
and maintenance of the vital processes, since the un-
hatched creature wastes almost no energy in physical
activity.
The white of egg is almost pure albumin with a little
water and some salts; the yolk contains about 30 per cent,
of fat and some albumin. The albumin coagulates at
about 170° F., but if it is exposed to a higher temperature
for any but a very short period of time, it becomes hard
208 A MANUAL OF HYGIENE AND SANITATION.
and difficult of digestion. A so-called " soft-boiled " egg
is scarcely more difficult of digestion than an uncooked
one, and is certainly more palatable to almost every one.
Eggs, milk, and cheese may be made into many nutri-
tious combinations which furnish food especially agreeable
to the sick, as well as to those whose appetite and digestive
functions have not been impaired.
Good meaty when deprived of its contained water, is a
concentrated food, and is used not only on account of the
large amount of nutriment it contains, but for its rich and
agreeable flavor. It represents much vegetable matter
converted into its present palatable and more digestible
form by the metabolic activity of the animals from which
it came. It contains all the essential food principles, the
carbohydrates, however, being present as muscle sugar or
iuosite and, as in milk, in very small proportion. In all
fresh meat there is much water, but more in lean meat
than in fat; fat bacon contains 60 per cent.; lean beef,
from 75 to 78 per cent, of water. As the proportion of
fat increases the quantity .of albuminoids or proteids
decreases : thus, lean beef may have only 2 per cent, of
fat to from 20 to 24 per cent, of proteids; while bacon
has about 24 per cent, of fat to 15 per cent, of proteids.
Of the varieties of meat commonly used, beef is the
most nutritious. Good beef should not be too pale nor too
dark, should show no blood clots, have almost no odor, be
elastic and not soggy to the touch, be well marbled with
clean, white fat, and have compact flesh. Dark beef indi-
cates that the animal was not properly bled, or has had some
febrile disease; wet and flabby meat, that it is approach-
ing decomposition. The flesh of young animals is more
tender than that of older ones, but not as digestible, partly
because the young flesh cannot be so thoroughly masticated
FOOD. 209
and the fibres so well separated. Therefore, veal is not as
digestible as beef, nor lamb as mutton. " Young flesh is
less stimulating and nutritious and more gelatinous than
that of the adult. " (Vaughan.) Veal should not be too
pale, as that indicates ante- mortem bleeding or too young
an animal. The calf should be at least one month old
before the killing.
Mutton is more digestible than beef, but not so nutri-
tious. Its flavor is objectionable to some. Pork is an
economical food for the poor man, as good pigs store up
three times as much of the food they eat as does the ox.
The flesh is also easily preserved by drying or smoking,
and ham and bacon are exceptions to the rule that dried
meats are more indigestible than fresh ones. Again, pork
fat furnishes much heat for cold weather by its oxidation
and combustion in the body. But it must be remembered
that it requires good digestive apparatus to dispose of it,
and that much pork is not to be advised for those of
sedentary habits.
The flesh of poultry is acceptable to most palates, if not
too old and tough. White meat is more digestible than
the dark, but not so nutritious or rich in flavor, since the
latter is more highly nitrogenous. Chicken broth is more
nutritious and more laxative than that made from mutton.
Fish is not sufficiently stimulating to constitute the
chief flesh diet of a people, but it furnishes variety, and
undoubtedly should be used largely by those subject to
neurosal affections, on account of its contained phospho-
rus. White- meated fish are more delicate in flavor and
more easily digested, but not so stimulating as those of
red flesh. Some fish are poisonous, either by nature or
from inhabiting foul waters; while any fish may become
so if undergoing decomposition. Shell-fish are particu-
14
210 A MANUAL OF HYGIENE AND SANITATION.
larly liable to develop poisonous ptomaines in the process
of decomposition, and, consequently, only such as are
absolutely fresh should be used. Oysters and clams which
have been taken from a water contaminated by sewage
may also convey the germs of infectious diseases, such as
typhoid fever; an instance of this having been proven in
the case of a recent epidemic of the latter disease in Con-
necticut, which was investigated and reported by Prof.
Conn, of Wesleyan University.
" The following meats should not be eaten: 1. The
flesh of all animals dead of internal diseases, or which
have been killed while suffering from such diseases, or
animals killed by overdriving. 2. The flesh of animals
with contagious diseases that may be transmitted to man.
3. The flesh of animals that have been poisoned. 4. The
flesh of animals with severe infectious diseases, as pyaemia,
etc. 5. Flesh that contains parasites that may be trans-
mitted to man. 6. All putrid flesh.'7 (Gerlach.)
Competent inspectors should be and are appointed by
Government and State authorities to examine the various
meats offered for sale in the large cities, and undoubtedly
do much good in preventing the sale of meat that is unfit
for use. Unfortunately, from false ideas of economy,
they are too few in number in many communities to be
able to attend to all the work that is required of them.
Coplin and Bevan give the following as diseases which
are to be specially guarded against, and also discuss the
symptoms of these maladies and the appearances they pro-
duce in the flesh and viscera of animals killed while suffer-
ing from them: In cattle, epidemic pleuro-pneumonia,
foot- and mouth-disease, contagious typhus, anthrax,
tuberculosis, actinomycosis, Texas fever, dropsical affec-
tions, and indigestion. In sheep, braxy, variola ovina,
FOOD. 211
black quarter, phthisis, fluke disease, and gid. In
swine, anthrax, hog cholera, measles, and trichiniasis.1
It should also be remembered that the intestinal para-
sites, such as tape- worms and round worms, often, if not
usually, gain entrance into the system through the inges-
tion of meat containing them in their embryonal or larval
Therefore, in cooking meat, every part should be heated
to at least 160° F. to destroy any disease germs or para-
sites it may contain, as very rare meat may still contain
these organisms in a living state. Tuberculosis, for
instance, may be incurred by eating flesh imperfectly
cooked, since its germs are hard to kill; though it must
be said that this disease is not so likely to affect the mus-
cular tissues of an animal as others of the maladies men-
tioned. The development of ptomaines in flesh may also
make it very poisonous, and this is especially likely to
occur in meats that have been kept a long time after kill-
ing or in those preserved in cans or other packages that
have been imperfectly heated or sealed.
Meat is cooked to improve it in appearance and to make
it more agreeable to the palate and digestion. The effect
of cooking upon muscle tissue is " to loosen the bundles
of fibrillse from each other so that they are readily torn
asunder or crushed by the teeth/7 Perfectly cooked flesh
is more savory than when it is either underdone or over-
done. Foster says that in the stomach "the natural
bundles of meat and vegetables fall asunder, the muscular
fibres split up into disks, and the protoplasm is dissolved
from vegetable cells.7' However, "if the meat be not
chewed properly but l bolted/ the solvent gastric juice can
1 Manual of Practical Hygiene, 1st edition, p. 132, et seq.
212 A MANUAL OF HYGIENE AND SANITATION.
only act on the exterior of the mass; while ' lumps ' offend
the stomach and arrest the gastric secretion.'7
Meat cooked before rigor mortis sets in may be tender;
cooked during the rigor, it is tough, and is masticated with
difficulty; after the rigor is past the meat becomes tender
again when cooked, provided it was so originally.
In cooking meat, the ultimate condition in which we
wish it to be should always be kept in mind, and pains
should also be taken not to overcook or use too high a
temperature. The processes pursued in making a good
soup or broth, and in cooking so that it may retain all its
juices, salts and flavors, are radically different. In the
first case, it is desired to extract as much of soluble con-
stituent of the flesh as possible, and to do this the meat
should be cut into small pieces and allowed to remain for
a time in cold water, this afterward being very gradually
raised to a temperature of about 160° F. In this way the
juices exude and the salts and soluble parts of the meat
are dissolved before the pores are closed by the coagula-
tion of the albumin.
On the other hand, if it is desired to retain the juices
and savor in the meat, the piece should be large as pos-
sible, that the surface exposed will be small in proportion
to the volume. The piece is then to be first subjected to
a temperature as high as possible, that the surface may be
cooked at once and the albumin coagulated, the juices
being thus prevented from escaping by the sealing of the
pores. In boiling this end is attained by plunging the
meat at once into boiling water; in roasting, by having
the fire or oven very hot. After this first heating it is
best to diminish the degree of heat somewhat, that the
subsequent cooking of the interior may go on more slowly
and the temperature within may not rise above the_coagu-
FOOD. 213
lating point to make the fibres hard and stringy. Meat
cooked in this way should be tender, juicy, and full of
flavor. Broiling or grilling is, of course, but a modified
roasting.
Soups and broths made of meat juices alone and without
the addition of other substances are stimulating rather than
nutritious, as they contain little albumin, carbohydrates,
or fat. However, if certain vegetables be added to the
soup, the latter will gain sufficient of these food-principles
and be highly nutritious, and such vegetable soups are of
great value in all schemes of economic cooking. Bones
are also of value on account of the salts, gelatine, and
other soluble organic matter which they contain, and
with vegetables they make especially nutritious and easily
digested soups.
The meat from which soup is made, on the other hand,
is not all that is desirable, for though it still contains albu-
min and fat, it has lost its salts and savoriness, and
is unpalatable and, therefore, not easily digested. It
needs something — a sauce or condiment, or preferably, a
meat extract, for meat extracts are nothing but thin soups
evaporated to dry ness or condensed. Or, if both soup and
the meat be taken at the same meal, the things lacking in
each are supplied in the other, and the needs of digestion
and nutrition are supplied.
Frying meat, as is commonly practised, should not be
condoned or tolerated, as it renders the albumin of the
flesh extremely tough, beside soaking it with fat or grease,
and thus greatly increasing the difficulty of its digestion.
But frying by total immersion in boiling fat is an excellent
way of cooking meats containing much water, and espe-
cially fish, for the boiling point of fat or oil is very high,
and the meat is instantly cooked on the outside, while the
214 A MANUAL OF HYGIENE AND SANITATION.
water in the interior, being converted into steam, prevents
the ingress of fat by its expansion, cooks the albumin, and
leaves the flesh in a light, flaky condition. But the fat
must be boiling hot when the meat is immersed, and the
latter must not be allowed to remain in the former longer
than just suffices for the perfect cooking.
Beef-tea, as ordinarily made, is only a thin extract of
beef, the stimulating properties of which will be consid-
ered hereafter. To make a -beef-tea containing any con-
siderable amount of nutriment, the meat from which the
juices have been extracted should be dried, pounded fine,
and all fibrous and tendinous portions should be removed.
This pounded beef should then be added to the liquid
extract, which then only is really a food. However, the
mixture should always be seasoned, even for the sick, that
it may be thoroughly acceptable to both palate and stomach.
In making the extract, remember that the meat should be
cut into very small pieces and added to cold water in about
the proportion of one pound of lean meat to one pint of
water, and that the whole should be brought to the boiling-
point very slowly.
The cereals form one of the most valuable kinds of
foods. All but rice contain considerable proteid matter —
from 10 to 20 per cent. — beside carbohydrates which pre-
dominate, some fat, and a goodly proportion of phosphates.
Rice has only 5 per cent, of proteids to 75 per cent, of
starch, but it is easily digested, and is, therefore, a valu-
able food for the young and the sick; it is also well fitted
for a chief food for dwellers in hot climates on account of
its low heat production.
Wheat is the most nutritious cereal, and bread made
from it is aptly called " the staff of life," since it is a
food which, with the addition of a little extra fat and
FOOD. 215
albumin, furnishes the essentials in proper proportion for
the support of life. Barley closely resembles wheat in
composition, and rye also is rich in nutriment, though
perhaps a little more difficult of digestion than wheat.
Oats are valuable on account of the large amount of fat
they contain — over 5 per cent. — beside a full share of
proteids, starch, and salt. Corn or maize, though not a
true cereal, furnishes a valuable food with considerable
fat; it also contains a vegetable fibrin. The proteid con-
stituents of the cereals are vegetable albumin, casein, and
gluten, the last of these being most abundant in wheat
and, perhaps, of the highest food value.
Grinding breaks up the grain and the starch granules of
the cereals, aids in separating indigestible parts, and renders
the starch much more suitable for cooking. Wheat flour
ground by the old method should be soft and smooth, but
that made by the new roller-process is more apt to be
slightly granular. It should not be too white, as that
indicates a lack of the proper proportion of gluten, and
should contain everything but the outer husk of the grain.
The inner coats should be retained in the flour, as they
hold a good part of the gluten and practically all of the
grain salts. Corn-meal should be dry and powdery, or,
at least, not too granular. Flour of any kind should be
kept well covered in a dry place, and should contain no
living organisms nor any adulterants.
Bread is practically made of flour, water, and salt;
though sugar, milk, etc., may be added to improve the
flavor. As flour and water alone make a tough and
indigestible mass, bread is leavened to make it easier of
mastication and digestion, and for this purpose either
yeast, baking powder, or aeration is employed. Yeast at
the proper temperature rapidly converts the starch or
216 A MANUAL OF HYGIENE AND SANITATION.
sugar into carbonic-acid gas and alcohol, the former of
which in escaping makes the dough porous and light, the
walls of the cavities it produces being kept from collapsing
by the tenacity of the gluten until the heat has fixed them
permanently. As the heat of baking dissipates both the
gas and alcohol, from 10 to 12 per cent, of the weight of
the flour used is lost by this method. Moreover, if the
fermentation goes beyond a certain point, lactic and acetic
acids are formed, and the bread becomes " sour/7 Con-
sequently, it has been advised that the yeast method be
discarded and that the leavening be done by means of
baking-powders or aeration. Carbonic-acid gas is evolved
from the baking-powders upon the application of heat and
moisture, and the bread is made light by the gas, with no
loss of food substance, and, if the powders are pure, with
nothing harmful being added to the bread. There should
be no alum or other adulterants in the baking-powders,
any more than in the bread itself. Alum unites with the
phosphates of the flour, rendering them insoluble and pre-
venting their absorption from the alimentary tract. Bread
may also be leavened on a large scale by forcing air or
carbonic-acid gas under high pressure into the dough, or
by mixing the flour with water heavily charged with the
latter gas. In this method, also, there can be no loss of
food material nor any detriment to the bread, provided
cleanly precautions are observed.
Good wheat bread should be almost white, light, sweet,
spongy, and with a crust easily broken and equal in bulk
to about one-quarter of the loaf. As considerable of the
starch has been converted into dextrine in the crust, the
latter is more easily digested than the interior of the loaf.
Fresh bread is not nearly so digestible as that which is a
day or two old. As stated, bread needs only a little added
FOOD. 217
fat and albumin to make it a perfect food, and this it gets
almost if not quite sufficiently in the butter which we
commonly use upon it.
The vegetables in common use are valuable articles of
food, in that they give us the larger portion of our carbo-
hydrates and also furnish an agreeable variety from day
to day. In the fresh state they contain considerable water
— from 75 to 90 or 95 per cent., the residue being mainly
one or the other of the carbohydrates. Potatoes exemplify
this well, since they contain but little proteids and fat,
and practically all of their solid matter is starch. On
account of their customary cheapness and ease of growth
and storage they are usually considered to be a good article
of food for the poor man, but it should not be forgotten
that other foods which are apparently more expensive may
actually at times be cheaper than potatoes, both on account
of containing those principles which the latter lack and
because they may require less expenditure of digestive
energy. Beets contain much sugar and are nutritious,
palatable, and easily digested. Cabbage, cress, spinach,
and other greens, are especially valuable for the organic
salts which they contain, and because they serve so well
as relishes. Celery and lettuce are nerve sedatives, and
asparagus acts as a diuretic and is thought to be of special
benefit to the kidneys.
The seeds of the leguminous group of plants, such as
peas, beans, lentils, etc., contain from 22 to 25 per cent, of
proteid matter in the form of vegetable casein, and almost
50 per cent, of starch. It is on account of this abundance
of food-matter that they make such a valuable addition
to soups and the like, and for the same reason they should
also be considered and used in any dietary where economy
of expense is to be a factor. Green peas and beans are
218 A MANUAL OF HYGIENE AND SANITATION.
much more digestible than those that have ripened and
dried, though, of course, they do not yield as much food,
weight for weight, as the latter.
All vegetables should be cooked so as to retain their
salts, or else the water in which they are cooked and
which contains these salts should be used in making soup
or broth, to be served at the same meal with the vege-
tables. This is especially advisable with regard to pota-
toes and sweet potatoes, as their soluble salts have much
to do with their digestibility. It is for this reason that a
properly roasted potato is always better than a boiled one,
and that steamed vegetables are both more palatable and
more digestible than those which have been cooked under
water. In fact, Mattieu Williams has even suggested that
possibly one reason why gout is so prevalent among Eng-
lishmen is because they habitually eat boiled vegetables
and throw away the water in which these have been cooked.
The salts not only help in the digestion of the starches,
but they furnish bases to unite with and render soluble
the irritating acids that produce the gouty symptoms. It
should also be remembered that the dried legumes should
always be softened by soaking before cooking, and that
they as well as other vegetables should be cooked, when-
ever possible, in soft water.
Fruits are especially valuable on account of their flavor,
acceptability to the palate, benefit to the digestion, and for
their laxative action. Ripe fruits may be eaten freely, but
in most cases, preferably early in the day. Eresh fruits
are usually better than those dried or otherwise preserved ;
but where the former cannot be had, the latter should be
used freely, and all should be used whenever possible
throughout the year. Green fruit, or that which has begun
to decay, should not be eaten, for obvious reasons.
FOOD.
219
Nuts are nutritious on account of the high percentage
of fat that most of them contain, but are difficult of diges-
tion unless carefully masticated. Recently pastes made
from various nuts have been placed on the market, and
are to be considered as an agreeable addition to our die-
taries. Prepared starches, such as arrow-root, tapioca,
sago, etc., are very digestible and, therefore, useful, espe-
cially in the preparation of food for the young or the sick.
The following diagram may be of service to some in
determining the value of certain food-stuffs.
PIG. 34.
RELATIVE VALUE OF STAPLE FOODS.
HEAT A ENERGY WATER FLESH A BONE f
C".' ' ..". '"~) c ) in
CHAPTEE VII.
STIMULANTS AND BEVERAGES.
THE essential function and property of stimulants is
to liberate some of the latent force of the body, and they
are of use and value in sudden emergencies, to tide the
system over important crises, to hasten a tardy convales-
cence, or, perchance, to whip up a flagging digestion so
that it may the better prepare food for the repair of waste
or the supplying of body fuel. Those stimulants, exclud-
ing drugs, with which we are most concerned are of three
classes, viz., nitrogenized vegetable stimulants, such as tea
and coffee; nitrogenized animal stimulants, as beef-tea and
meat-extracts; and alcohol. All these are " force-libera-
tors," though alcohol may sometimes act the part, in more
moderate measure, of a "force-producer," and it is well
to remember that they scarcely give anything at all to
renew or replace the energy which they set free.
This being so, care should always be taken that some
food may be supplied during or shortly after the stimula-
tion produced by the agents in question, in order that the
body may have a new store of force to replace that which
has been liberated. Especially is this necessary in cases of
sickness, and as the soluble carbohydrates furnish fuel and
consequent heat and energy to carry on the vital pro-
cesses, these even more than other kinds of food are to be
supplied and will generally be well received and utilized
by patients or others in need of stimulation; and, just as
we must not depend on stimulants alone to the exclusion
STIMULANTS AND BEVERAGES. 221
of food, so also must we take care not to continue their
use any longer than is necessary to attain our object, and
likewise must not over-stimulate or carry the action so far
that the body is left poor and weaker in force than before
the use of the stimulants began.
For example, beef-tea constantly stimulates the vital
and nervous functions to greater activity, this requiring
that either tissue or food be oxidized to produce the neces-
sary energy. But beef -tea, as ordinarily made, gives no
food in itself, and, unless this be otherwise supplied, the
body tissue must be consumed and the result must be in
the end disastrous; and yet this is what occurs to many
patients through the mistaken idea that beef -tea is both
nourishing and stimulating. When " whole beef-tea "
(the recipe for which has already been given) is used these
remarks do not apply, since it contains some true food,
though even here soluble carbohydrates may be wisely
added.
The stimulating factors in ordinary beef -tea are the
extractives, such as kreatin and kreatinine, which are pro-
ducts of the wear and tear of life, intermediate between
living, active tissue and the final excretory matters, such
as urea and uric acid; hence, they can have little, if any,
real food value. Beside these the beef-tea contains only
the salts of the meat, which, though valuable, are not force
producers.
The active principles of the nitrogenized vegetable stim-
ulants resemble very closely in chemical composition not
only the meat extractives, but also those drugs, like
strychnine, which are used in medicine as tonics and cere-
bro-spinal stimulants, and they act physiologically in a
similar though milder manner.
As beverages tea, coffee, and cocoa supply fluid for the
222 A MANUAL OF HYGIENE AND SANITATION.
system and that stimulation of the assimilative functions
that gives the sense of comfort after their use; cocoa and
chocolate having also the advantage of supplying some
food. But these beverages can all be abused in their use
as readily as can beef-tea or alcohol, and " tea- or coffee-
drunkards" are not uncommon in our hospitals or in
private life. The teacup is not always the one that
" cheers but does not inebriate." Women especially who
drink much tea are apt to be nervous and dypseptic, to
have the " tea-drinker7 s heart," and to suffer from head-
aches and neuralgias. They depend upon tea to take the
place of food, and soon use up what little store of force
they may have had, since they fail to replenish it with
new fuel-food.
Men are more addicted to the use and abuse of »coffee,
and often manifest symptoms directly traceable to it.
While caffeine increases heart action, and may be used to
advantage in cases of cardiac debility, for the same reason
it should be taken with caution and in moderation where
the cardiac action is already too vigorous. Vogel has
advised the use of strong coffee with cream as a tonic and
food in debility accompanying the acute diseases of chil-
dren.
It is interesting to note that among all nervous, ener-
getic people the use of some one or the other of these
stimulant beverages is common, and that " total abstain-
ers" from alcohol seem instinctively to take to tea or
coffee. And while it is probably theoretically true that
the healthy person would better abstain entirely from the
use of stimulants, except in emergencies or at rare inter-
vals, yet this almost universal demand and use of them
probably indicates that under our present high tension of
living there is a practical physiological demand and need
STIMULANTS AND BEVERAGES. 223
for them that perhaps had better be satisfied in a measure,
but with moderation and judgment.
Alcohol Liebig says " alcohol stands only second to
fat as a respiratory material/7 but adds that " the same
effect could be produced in the body by means of saccha-
rine and farinaceous articles of food at one-fourth or one-
fifth the cost." Fothergill also holds "that the chief
portion of the alcohol ingested undergoes consumption in
the body/7 but insists that " the question of ' alcohol as
a food J can never be separated or divorced from that of
' alcohol as a stimulant' or as a force-liberator." Again,
Liebig writes, that " the use of spirits is not the cause but
the effect of poverty. It is the exception to the rule when
the well-fed man becomes a spirit-drinker. On the other
hand, when the laborer earns by his work less than is
required to provide the amount of food which is indispen-
sable in order to restore fully his working power, an
unyielding, inexorable law or necessity compels him to
have recourse to spirits. He must work; but in conse-
quence of insufficient food, a certain portion of his work-
ing power is daily wasting. Spirits, by their action on
the nerves, enable him to make up the deficient power at
the expense of his body; to consume to-day that quantity
which naturally ought to have been employed a day
later." This may also be the case where there is an
abundance of food, but where it is improperly chosen for
the needs of the individual or ruined in the preparation
by bad cooking. Education in the principles of the
scientific and economical selection of food and its prepara-
tion may thus become a means of preventing those diseases
that depend on or are aggravated by insufficient or im-
proper food, and consequent alcoholic excesses. The effect
of alcohol upon the weak and savage races is much more
224 A MANUAL OF HYGIENE AND SANITATION.
marked and disastrous than upon the civilized and strong;
so it harms the health of the underfed and overworked
much more than it does that of the well-fed man of
means and leisure, and women and children more than
adult men. This latter point is to be remembered in
practice.
Remember also that, while alcohol is partially a respir-
atory stimulant, it is a force-liberator and consumes the
body store, and unless given with other readily oxidizable
food the risk is run of putting a patient " in a grave never
dug by Nature/' especially where there is already danger
of the patient sinking from exhaustion. But it is just in
these cases, when given with other food, that we find alco-
hol a most valuable therapeutic agent. Give it with foods
that produce heat and force — i. e., some form of the solu-
ble carbohydrates, as maltose, malt extracts, milk, milk-
whey, or even sugar. "Where the assimilative powers are
weak it may be advantageous or necessary to partially or
wholly predigest these foods; but above all, remember to
replace what alcohol takes from the body, or physiological
bankruptcy will ensue. Note also that, though alcohol
may be in one sense a food, it is a very costly one, and
that intoxication must occur long before a man could get
the equivalent of a full meal.
Alcohol is to be used in sickness practically to sustain
the vital powers, to meet emergencies, and to lift the
patient over obstructions in the road to health; and such
use requires a thorough knowledge of its action coupled
with the highest judgment.
In malt liquors there is considerable maltose left un-
changed, thus combining with the alcohol a soluble carbo-
hydrate of the highest value, and these brewed ales, etc.,
may often be used with benefit as tonics, especially where
STIMULANTS AND BEVERAGES. 225
convalescence is prolonged. The stronger distilled liquors
are diffusible cardiac stimulants, and are especially valu-
able in emergencies, but the continued use of them must
only be advised with great caution. Fothergill gives two
excellent rules for the use of alcohol by the healthy :
" First, never have alcohol in the brain when it has work
to do; second, a little alcohol betwixt a man and past
trouble is permissible; but it is not well to put a little
alcohol in front of a coming trouble. " Murchison, in
his work on Fevers, lays down these rules for practice,
which it would be well for all to adopt : u What are the
conditions of the animal economy in which alcohol may
be of positive use? That there are such conditions, I
believe cannot be denied by any one who has honestly
studied the subject; but they are not the conditions of per-
fect health. It is especially when the circulation is weak
or sluggish that a daily allowance of alcohol may do good.
Thus : 1. Alcohol is useful in the course of most acute
diseases, when the organs of circulation begin to fail, as
they are apt to do. A moderate quantity usually suffices.
The large quantity still sometimes administered may do
harm by inducing congestion of internal organs. 2. In
convalescence from acute diseases, or from weakening
ailments, when the circulation remains feeble and the tem-
perature is often subnormal, alcohol is useful in promoting
the circulation and assisting the digestion. 3. In persons
of advanced life the circulation is also often feeble, and a
moderate allowance of alcohol often appears to be bene-
ficial. All other conditions of the system marked by
weakness of the muscular wall of the heart, whether per-
manent or transient, are usually benefited by alcohol."
vAlcohol is a good servant, but a bad master. King Cham-
bers says : " Let alcohol be taken never as a stimulant or
15
226 A MANUAL OF HYGIENE AND SANITATION.
preparative for work, but as a defence against injury
done by work, whether of mind or body. For example,
it is best taken with the evening meal or after toil. Let
the increase in the desire for and the power of digesting
food be the guide and limit to the consumption of all
alcoholic liquids. Let the forms be such as contain the
least proportion of fusel oil. Let all with an hereditary
tendency to hysteria or other functional diseases of the
nervous system refrain from its use altogether, even
though as yet in good health."
Beverages.
To comment individually upon the multitude of non-
alcoholic and non-stimulating beverages that are now more
or less generally used, is both impracticable and unneces-
sary, nor will an attempt to classify them be of much value.
For the most part they serve only to please the palate;
though if in this way they bring about a greater ingestion
of fluids when these are needed, their service cannot be
considered a vain one. For it has already been stated
that an ample supply of drinking water or other fluids
taken daily and habitually is essential to the satisfactory
removal of the various waste matters from the body, and
that without it the latter may readily develop conditions
favoring disease.
Moreover, it is true that certain gases and salts held in
solution in such beverages increase this excretory action,
and may be highly beneficial in appropriate cases; but it
should be a matter of caution that where such therapeutic
results are thought to be necessary, competent medical
advice should be the guide as to the kind and quantity of
the agents used. This comment is justified by the fact
that of late many substances possessing decided physio-
STIMULANTS AND BEVERAGES. 227
logical power have been advertised and sold in the form
of one beverage or another directly to the laity, who, being
incompetent to judge as to whether or not such substances
are actually needed in their individual cases, may actually
do themselves much harm in this way.
Only such beverages, then, as are quite simple in their
nature or as are advised by competent medical authority
should be used. If they are artificially made and water
is the solvent fluid, as it will be in most cases, there should
also be certainty that it comes from a clean and safe source,
lest it carry the germs of disease. There is no doubt that
frequently the cheaper bottled drinks which are dispensed
so generally are made from water that has been subject to
more or less dangerous pollution, and there is the addi-
tional risk that arises from the imperfect cleansing of the
bottles for these liquids which have been returned to be re-
filled. A little thought as to the dangers which do exist in
relation to this matter will be convincing as to their gravity.
Many of the most popular beverages are highly charged
with carbonic-acid gas under pressure, and the fact that
so much of this gas can be taken into the system in this
way without apparent harm, and its free elimination,
would seem to be additional evidence that it in itself could
not be so very harmful in the atmosphere, even when in
proportions considerably greater than the normal.
In conclusion, it may be said that a free use of all such
beverages as are known to be clean, safe, and wholesome
will probably be found to be entirely favorable to health,
unless there be some contraindicating reasons peculiar to
the individual himself; and that their substitution when-
ever possible in place of the alkaloidal and alcoholic stim-
ulants is to be commended on hygienic as well as other
grounds.
CHAPTEK VIII.
PERSONAL HYGIENE.
THE proper consideration of this subject demands an
ample volume rather than the limits of a single chapter,
for the ultimate aim of all sanitary work is the preserva-
tion and betterment of the health of the individual, and
beside, the factors that affect the well-being of the person
are so multitudinous in their number and in their phases
that no brief discussion can comprehend them all.
However, much that pertains to personal hygiene and
that requires no repetition for its application has already
been given in the preceding pages; so that it is hoped that
if the reader will exercise that virtue of common sense
and reflection that is so essential in this study, the remarks
to be added will be helpful in suggestion and in answering
many questions, even though they may not be considered
in any way as complete discussions of the respective
themes.
Each age has its own requirements, and that which may
be entirely satisfactory or permissible at one time may not
be so at another. To attaiu the best results it will often
be necessary to even anticipate with prophylactic measures
the birth of the child; and broadly speaking, much of the
welfare of future generations lies in the care of those now
living.
The advances in physiological and biological science in
recent years have done much for all humanity, but in no
respect, perhaps, have they been of more service than in
PERSONAL HYGIENE. 229
determining the great influence of environment and in
establishing the fact that the presence or absence of dis-
ease is oftentimes, if not always, due as much to the pre-
disposing conditions and physical status of the individual
as to external and exciting causes. What may cause only
a trifling ill in one may bring about most serious evils in
another whose environment is not so fortunate.
Life has been defined as the power of an organism to
continually adjust its internal conditions to its external
conditions, and as long as this is done satisfactorily life
persists. The secret of personal hygiene and health,
then, must lie in determining the relationship between
the internal and external conditions of the individual's
organism.
" Know thyself " is advice good for the body as well as
for the mind or soul, and knowledge of the right kind can
do no harm. He who knows his personal and physical
nature and acts accordingly is well equipped to fight
against the ills of life, and the study of the relationship
above referred to will help the thinking man so to care
for himself that in all probability his days will be pro-
longed.
But a caution or two must be interpolated here. It is
well known that "expectant attention " too persistently
directed toward a certain organ may lead to decided alter-
ations or disturbances in the functions of that organ; and
again, unless one well understands the mysteries of human
physiology, a little imperfect or insufficient information in
this respect may lead to the assumption or pursuit of habits
and practices actually dangerous to health . Too much ill-
advised care and attention may be just as full of risk as
too little, and physiological egotism without a sound basis
may have a bitter reward.
230 4 MANUAL OF HYGIENE AND SANITATION.
What is needed is that each one should study carefully
the phenomena of his daily life, should determine care-
fully and accurately the purpose and reason of each of
the respective functions, and then, not forgetting their
mutual interdependence upon one another and that all
should work in harmony, should endeavor to do that
which will best facilitate the functional activity with the
least expenditure of energy.
This may be more or less readily taught to and incul-
cated in the young, but with much greater difficulty can
we affect tie mature or aged; for we are all creatures of
many habits, and the impress of these may resist to the
utmost any and all endeavors to modify or remove them.
To quote what has already been written: " The essence
of sanitation is to secure perfect health, to increase the
inherent power to resist noxious and harmful influences,
and to make all the surroundings and environments of the
body pure and free from depressing factors. "
With this preface, the following discussions are added
in the hope that they may be of some assistance in deter-
mining the way of right living and in securing the welfare
and health of every individual.
Heredity.
In the broadest sense heredity is a characteristic jointly
possessed by two cells, furnished by respective parents,
which join and form a fused cell, which carries on its
evolution under certain governing impressions indelibly
stamped by the two parental lines of descent; but, in the
ordinary use of the term, it may be defined as the trans-
mission to the offspring from parent or ancestor of a trait,
type, temperament, characteristic, or predisposition which
has a governing or influencing effect upon the growth or
PERSONAL HYGIENE. 231
nature of that offspring. This transmitted impression
may be either for good or for evil. Consequently, as hygi-
enists, we must use the influence and power that we have
to further the transmission of beneficial or elevating char-
acteristics only, and to prevent the bequest of harmful
influences and hereditary diseases to the generations to
come. " The germ of the unborn infant must be complete
and untainted in all its nature, otherwise we cannot hope
for a vigorous and perfect growth or development."
As the family is the foundation of the State, and society
is a congregation of men for the purpose of acquiring
greater power and more comforts through mutual co-opera-
tion, the latter, whether domestic or civil, has some right .
to make men understand that they must care for the health
of the generations to follow, and to enact just laws look-
ing to the prevention or obliteration of transmissible
infirmities. And history seems to show that no great
nation has ever been destroyed or overwhelmed until its
people had first neglected or abused the laws of hygiene,
heredity, and sociology.
We find that a married couple have generally, beside
themselves, the welfare of five human beings within their
keeping. To produce healthy children and ones not prone
to disease both parents should possess good constitutions,
and they should take great care not to weaken these by
excesses of any kind, physical or mental, nor, as far as
lies in their power, by any chronic disease. It is evident
that children of parents that have been conscientious
observers and followers of Nature's laws must have a
better chance for health and superiority all their lives.
In this climate the proper age for marriage is considered
to be about twenty-four or twenty -five for the man, and
nineteen or twenty for the woman, though this must vary
232 ^ MANUAL OF HYGIENE AND SANITATION.
with the state of development of the parties concerned.
Some of both sexes mature at a considerably earlier period
than do others, and it would be unjust to say that they
were not fit for the duties of marriage till they reached
the age of slower-growing ones. Usually, however, before
the ages given, development is not complete and the whole
organism is in a transition state. We know that the use
of any organ before it has attained its complete growth or
development is very apt to cause exhaustion, or perhaps
premature degeneration of that organ, and we cannot but
believe that children developed in immature sexual organs
must be deficient in true vital force and energy. It is
often noticeable that a child apparently strong and vigor-
ous may have but little power to resist disease, or may even
be strongly predisposed to some infirmity; in such cases
there will likely be some defect or taint in the parent stock.
Distinguishing characteristics are more apt to be trans-
mitted in the early married life of parents, because their
organs and forces are then more vigorous; but if a couple
marry when quite young, and before their own organs are
fully developed, their elder children may be more deficient,
mentally and physically, than their later ones.
Late marriages are not likely to be as fruitful as earlier
ones, possibly owing to the increased difficulty of parturi-
tion on the part of the mother and her consequent unwil-
lingness to undergo the ordeal more than a few times.
But healthy middle-aged persons may have even healthier
children than those who have married too early.
In features, constitution, sense-organs, shape of head,
etc., the child is most apt to resemble the father; while it
will likely follow the mother in the shape of the trunk and
in the formation of internal organs. The character and
mental qualities of the child may come from either parent
PERSONAL HYGIENE. 233
or both. Maternal impressions during pregnancy undoubt-
edly often have a marked effect upon the coming infant.
Hereditary influences are generally transmitted directly
from parent to child, but we occasionally find a cessation
of the trait or predisposition for one or more generations
and then a recurrence. To such a peculiarity we give the
term atavism.
A disease may be truly congenital — that is, transmitted
directly from parent to offspring — as syphilis, scrofula,
etc. ; or there may be only an inherited predisposition to
the disease, as toward tuberculosis, etc. Physicians have
thus a twofold duty : first, to do all they can to guard
against the transmission of such diseases; second, to com-
bat the disease or any tendency toward it as soon as any
symptoms thereof are discovered or it is suspected in the
child. The first duty can be accomplished, theoretically,
by preventing generation and production on the part of
those unfit to produce offspring, and practically, within
certain limits, by fighting the causes and their effects in
the individual, especially at the ages or times when these
have the greatest force or are most apt to manifest them-
selves. For the second, the child must be immediately
placed in the most favorable hygienic surroundings, and
everything possible done to prevent the further develop-
ment of the disease or predisposition. In many cases
such early interference will accomplish much good, and the
disease may be averted entirely. Especially is this true
of those inheriting the tuberculous diathesis.
The most important of the hereditary or transmissible
diseases are syphilis, tuberculosis, scrofula, cancer, gout,
hysteria, epilepsy, certain physical deformities, certain
skin diseases, insanity, and criminal tendencies of various
kinds. But what may appear to be a direct and actual
234 A MANUAL OF HYGIENE AND SANITATION.
inheritance of a disease may only be the production of
the disease in that person by the same agents, environments
and morbid conditions as caused or favored the disease in
the parent. However, even here there is very possibly a
transmitted predisposition to the acquirement of the dis-
ease, rendering it all the more easy for it to manifest its
symptoms upon slight provocation.
There should be no haarriage between persons inheriting
predispositions to the same disease, especially if they be
relatives, and " a person affected with hereditary or well-
marked constitutional syphilis, or having a strong con-
sumptive taint, or tendency to mental unsoundness, should
not marry at all."
Defective eyesight is very apt to be transmitted to chil-
dren, and the latter should be carefully examined and, if
necessary, fitted with proper glasses before being placed
at school or at any work requiring much use of the eyes.
Infirmities which do not prevent marriage from being
fully accomplished, or which do not tend to the degenera-
tion of the offspring, are not good reasons alone for forbid-
ding marriage, but all that have such a tendency are. A
man should not marry a woman too far advanced in life,
nor one that is very feeble, delicate, or deformed, espe-
cially as to the chest or pelvis. Hysteria, convulsions
and epilepsy due to organic disease should prevent a
woman from marrying, though some extremely nervous
and hysterical women are much benefited by marriage, and
have healthy children. So with many women who have
uterine congestions and displacements before marriage.
Evidence seems to indicate that marriage between rela-
tives is reprehensible, the danger increasing with the near-
ness of relationship, the children of such marriage being
prone to disease and to defects in the sense-organs, espe-
PERSONAL HYGIENE. 235
cially the eye and ear, or in mental qualities. This is
probably because the strong or advantageous points or
characteristics do not seem to be transmitted either in
man or animals with the same ease or readiness as are the
faults or weaknesses. However, any advice on the subject
must depend upon the special circumstances in each case,
but chiefly on the health and degree of relationship be-
tween the parties.
Exercise.
Exercise is generally considered to mean simply the
action of the voluntary muscles, but it has a wider mean-
ing than this. Every organ in the body is capable of
being exercised in some way or other; and if not prop-
erly exercised an abnormal state is almost certain to
ensue. " Life is organization in action." Each organ
has its own special stimulus, and if this be normal in
amount and character, we should have health. Also, the
trained use of an organ makes it more effective in the
performance of its functions. But deficiency in exercise
favors a lack of nutrition, wasting in size and eventually
degeneration of tissue; while, on the other hand, too much
work may favor hypertrophy and tissue degeneration.
Proper muscular exercise is highly beneficial to health,
and in the end actually necessary to the proper perform-
ance of functions in other organs; it is consistent with
and necessary to health. But, to be of value, the exercise
must consist of movements of sufficient force to necessitate
energetic contraction of the muscles; we must do work.
This necessitates resistance as an element, and we may
define physical exercise as voluntary labor. We need the
resistance to obtain the proper contraction of the muscles,
the contraction for their disintegration, the disintegration
236 A MANUAL OF HYGIENE AND SANITATION.
for their renewal, etc. ; for we know that upon the con-
stant destruction and disintegration of tissues depends
their subsequent renovation, and that the strength and
vigor of all parts of the body and of the whole depends
upon its newness.
Beside the fact that proper physical exercise makes the
voluntary muscles larger, harder, stronger, and more
quickly responsive to the will, and that it increases the
functional capacity of the involuntary muscles employed,
it largely promotes health and strength by quickening the
circulation and increasing the respiratory powers. During
muscular action (contraction) there is a conversion of
potential energy into motion, a call for more food, an
increased demand for and consumption of oxygen, and an
increased production of and elimination of carbonic acid
and other waste matters.
This increased demand for oxygen and elimination of
carbon dioxide necessitates increased action of the respi-
ratory organs — the lungs, and this is one of the greatest
advantages of physical exercise. The respirations are in-
creased in frequency and depth, the lungs expanded, the
air vesicles flushed out and refilled with each inspiration.
Doubtless many cases of pulmonary tuberculosis could be
prevented or cured if only people could be taught to take
proper exercise and to breathe properly, for we rarely find
the lungs fully expanded except in the outdoor worker or
athlete. Consequently, the movements of any given exer-
cise should be with speed and force sufficient to quicken
and deepen the respiration; and, conversely, if any severe
exercise is to be undertaken or a course of training begun,
especial care must be had to develop the lung capacity.
A man walking at the rate of four miles per hour
inspires five times as much air as when reclining at rest,
PERSONAL HYGIENE. 237
which latter amount is, for an adult, about 480 cubic inches
per minute. Or, as Pettenkofer has shown, a man on a
day of rest absorbs 25 ounces of oxygen and throws off
32 ounces of carbon dioxide and 29 ounces of water; on a
day of work he absorbs 33.6 ounces of oxygen and ihrows
off 45 ounces of carbon dioxide and 72 ounces of water.
In other words, the elimination of pure carbon on a work-
day is more than three-fourths of a pound.
Muscular exercise is necessary, therefore, for the proper
elimination of waste carbon from the body, and, as the
action of the muscles is checked and lessened if the carbon
dioxide produced by their action is not immediately carried
off by the blood and eliminated by the lungs, it follows that
during exercise there should be nothing to impede the cir-
culation or the action of the chest and lungs, and that all
tightness of clothing, especially about the ^aist, neck, and
chest, should be avoided. Moreover, inasrr^ stheamount
of carbon dioxide and other waste mati - ; eliminated is
so very much increased during exercise, a much larger
amount of pure air is needed, and all rooms and buildings
wherein exercise is to be taken should be well ventilated.
After exercise an increased amount of carbonaceous food
and of water must be supplied to replenish the system for
what has been eliminated. The increase of carbon is prob-
ably best given in the form of fat rather than the carbo-
hydrates, though there is some difference of opinion on this
point; and of all fluids, water is doubtless the best in ordi-
nary cases for training. As a general rule, alcohol is harm-
ful, because it benumbs and deadens the nerves and will,
and, as every voluntary impulse must originate in the brain,
anything that interferes with the communication between
it and the muscles must lessen the promptness with which
they respond and the consequent efficacy of their work.
238 4 MANUAL OF HYGIENE AND SANITATION.
The use of a small quantity of malt liquor, however, as a
tonic or after the exercise is finished may not be harmful,
but the decision as to its need or use should be left to the
physician or trainer rather than to the one taking the
exercise.
By exercise the action of the heart is increased in force
and frequency, the pulse is made full and strong if the
work be not too excessive or sudden, and the flow of blood
and other fluids is increased throughout the whole body.
As long as the heart is not overtaxed the pulse beats are
regular and even, though suddenly increased exertion may
make the rate very rapid. Ordinary exercise increases
the rate from ten to thirty beats per minute. Excessive
exercise leads to palpitation and hypertrophy of the heart
(one reason why any training should be under a competent
trainer) ; but, on the other hand, deficient exercise leads to
a weakening of the heart-action, and probably to dilata-
tion and fatty degeneration. If at the beginning of a new
exercise the heart-action becomes irregular, rest should be
taken, and the exercise then begun in a more gradual way.
The heart stimulus is due to the increased amount of blood
in its cavities, but it should be remembered that the venous
circulation is largely due to the muscles. " Every muscle
is a little heart/' and these, by their contraction, con-
stantly tend to drive the blood onward to the true heart
and lungs.
Exercise greatly increases the amount of perspiration
from the skin, this perspiration containing water, salt, and
considerable waste matter. The evaporation of the water
tends to keep the body cool; but there is not much danger
of chilling the body during exercise, on account of the
great heat production. As soon as work is stopped heat
production is checked, the body cools off rapidly, and then
PERSONAL HYGIENE. 239
there is danger of chilling unless more clothing be added.
Flannel is best for this, because it is a non-conductor of
heat, and prevents too rapid cooling of the body. Keep
the skin clean so that the sweat-glands may be unob-
structed in the performance of their functions.
Exercise increases the appetite, partly because of the
increased demand of the muscles for food and partly on
account of the increased circulation of the blood through
the liver and the vessels of the alimentary tract, this
causing a more perfect digestion of food.
If exercise be taken too soon before meals either the
stomach, by calling the blood from the exhausted muscles,
will prevent their proper repair and rest; or the muscles,
calling the blood from the stomach, will prevent the proper
formation of the gastric juice when food its introduced. If
exercise be taken too soon after eating, it is apt to prevent
the flow of blood to the stomach and the formation of
gastric juice; or, by forcing the contents of the stomach
into the intestines before gastric digestion is completed,
and before the food has reached a condition in which the
intestines can make use of it, to cause intestinal irritation
and indigestion.
Proper physical exercise favors a symmetrical brain
development, as exercise of the functions of the centres
governing the action of the muscles must favor the growth
and development of those centres. " Hand culture, apart
from its value per se, is a means toward more perfect brain
culture;7' and exercise by itself alone is truly educational,
although this feature of it may be more fully developed
and emphasized by proper systems and methods. The
great trouble is that it is extremely liable to be misap-
plied, misunderstood, or neglected.
The aim of training should be to increase the capacity
240 A MANUAL OF HYGIENE AND SANITATION,
of the lungs and the breathing power, to make the muscles
more powerful, more responsive to the will, and their
capacity for endurance greater, and to lessen the amount
of adipose tissue. Systematic exercise helps one to resist
disease, because by it waste matters are carried off, pores,
glands and organs are kept active and healthy, and active
tissues take the place of weak and sluggish ones.
Fatigue is due to lack of contractile material in the
muscles to continue work, to the exhaustion of nerve-
force and motor impulses from the brain, and to accumu-
lation of waste products in the muscle.
Active exercise is that brought about by one's own
movements ; passive, that produced by something outside
or collateral to one's own power.
It is hard to determine how much exercise any given
person ought to take, as the personal equation varies so
much. The average healthy man should do work to the
equivalent of 150 foot-tons daily. The work of walk-
ing on a level at the rate of three miles per hour is said
to be equal to that of raising one-twentieth of the body
weight through the distance walked. According to this,
a man of 150 pounds in walking one mile does work equal
to 17.67 foot-tons, and he would have to do work equiva-
lent to walking about nine miles at the above rate to get
the proper amount of daily exercise.
This seems like an excessive amount, but if the work
done in one's daily vocation be taken from this, it will not
leave so very much for the daily health-task; and while the
natural disinclination of many to exercise grows stronger
by indulgence, and while urgent reminders are wanting and
the evils arising from the neglect, abuse, or misuse of exer-
cise are not so very immediate or apparent, they are still
certain and not at all consistent with good and perfect health.
PERSONAL HYGIENE. 241
Bathing1.
In health we make use of baths and bathing for the
cleansing of the body, the stimulation of the functions of
the skin, and as a tonic to the whole system. A proper
bath properly taken is exhilarating and thoroughly en-
joyable. Baths are also to be employed in sickness as a
means of cure, but such use of them is foreign to the
present discussion.
Dr. H. C. Wood says: " Cleanliness and the mainte-
nance of the proper condition of the skin require the use
of the bath at least twice a week. In some very delicate
persons the general bath produces marked depression, but
this can almost always be avoided by the use of very hot
water. If the hot or warm bath be employed habitually,
it should be preferably taken at night, and, unless under
very exceptional circumstances, the hot bath should always
be followed by cold sponging or the cold shower-bath, or
by a plunge into cold water. " The temperature of a cold
bath may be from 40° to 75° or 80° F. ; that of a tepid
bath, 75° to 85° or 90° F.; a warm one, 85° to 100° F.;
a hot one, from 100° to 110° F., or even hotter. A cold
bath is taken not so much for its cleansing as its tonic and
stimulating effects; the others are used mainly for their
cleansing properties, though if followed by the cold
sponge, shower, or dip the sense of exhilaration produced
will be marked.
Cold baths taken immediately after physical exercise
while the body is still warm, but after perspiration has
ceased, and followed by good rubbing and friction of
the skin, dispel fatigue and give a sense of buoyancy
and lightness. The shock of the first contact of the
water to the skin is but momentary, and can be withstood
16
242 A MANUAL OF HYGIENE AND SANITATION.
by most persons, unless there be serious organic disease;
and the reaction produced certainly compensates for the
momentary discomfort. If the bath be taken in the open
air, there is the additional benefit of a plentiful supply of
fresh air for the lungs, of the physical exercise and
increased circulation induced by swimming or combating
the surf, and, if in the sea, of the stimulation of the skin
by the salt. In fact, sea bathing may be advantageous to
a marked degree where the circulation and action of the
skin are sluggish. Or a sea-bath can be imitated at home
by adding about one pound of salt to the gallon of water.
Those who are subject to organic heart disease should
not indulge in sea-bathing nor in deep fresh-water bathing
where a sudden tax may be made upon the strength and
the heart-action be disturbed or checked. Women who
are menstruating or who are in the later months of preg-
nancy should not take cold baths.
Baths should not be taken too soon after meals, because
digestion may be lessened or entirely stopped by the blood
being called from the stomach to the skin and muscles, and
nausea and vomiting thus induced. " There can be no
doubt that many of the cases that are called e cramps/
and which frequently result in drowning, are due to this
cause. "'• In cold baths the head should be immersed first,
i( to avoid increasing the blood-pressure in the brain too
greatly, which might result if the body were gradually
immersed from the feet upward.772
The following rules, issued by the English Royal Hu-
mane Society, are worth noting : " Avoid bathing within
two hours after a meal, or when exhausted by fatigue,
or when the body is cooling after perspiration. Avoid
i Robe's Text-Book on Hygiene. 2 Ibid.
PERSONAL HYGIENE. 243
bathing altogether in the open air, if, after having been
a short time in the water, there is a sense of chilliness,
with numbness of the hands and feet; but bathe when
the body is warm, provided no time is lost in getting
into the water. Avoid chilling the body by sitting or
standing undressed on the banks or in boats after having
been in the water. Avoid remaining too long in the
water, but leave the water immediately if there is the
slightest feeling of chilliness. The vigorous and strong
may bathe early in the morning on an empty stomach;
the young and those who are weak had better bathe two
or three hours after breakfast. Those who are subject to
giddiness or fainting, or suffer from palpitation or other
sense of discomfort of the heart, should not bathe (out of
doors) without first consulting their physician."1
After any kind of a bath the body should be thoroughly
dried, not only to restore and accelerate the circulation of
the skin by the friction and to prevent the cooling by the
evaporation of the water, but also to prevent chafing and
eczematous eruptions where the skin is subject to friction
of clothing. Warm or hot baths should not be taken if
the person is to be exposed to the cold within several
hours, and the same rule applies to Turkish, Russian, and
vapor baths: so these latter should not be taken away from
home in cold weather, unless the bather takes pains to rest
well after the bath, and then to wrap up well before going
into the open air.
In all warm baths in health the principal object is to
secure the cleansing effects, and to be effective their use
must be systematic. The pores of the skin are self-
cleansing only to a certain degree, and the free use of
1 See also " Sea Air and Sea Bathing," by Dr. John H. Packard.
244 A MANUAL OF HYGIENE AND SANITATION.
warm water is most beneficial in removing dry epithe-
lium, sweat, dirt, and grease. If the pores of the skin
are obstructed there are not only irritation and eruptions
of the skin produced, but more work is thrown upon the
kidneys, and these if affected will break down the quicker.
Soft water is to be preferred for ordinary bathing and
washing, because it often prevents or reduces cutaneous
irritation, and because it saves soap.
A Turkish bath consists : 1. Of a dry, hot-air bath at a
temperature of from 120° to 170° F., or even higher, from
ten to thirty minutes. This causes in most persons ex-
treme perspiration, with no sense of discomfort, but rather
a very pleasant sensation. After this come : 2. A hot
shower-bath to wash off the sweat. 3. Shampooing,
massage, and scrubbing, to thoroughly remove all dirt,
loose epithelium, and perspiration from the skin. This
is in moist air at from 100° to 110° F. 4. A warm
shower-bath gradually changing to a cold one, and then
a thorough drying of the body and a rest for a quarter or
half an hour. A Russian bath differs from this only in
that moist air at 150° F., or less, is used instead of dry
air for the first bath.
It has been said " that a person ought never to stay in
either the hot air or steam-room if in any wise oppressed,
or to use very cold water afterward if one feels any
shrinking from it." Nor should one who is very corpu-
lent or subject to organic heart disease take a Turkish or
Russian bath without the advice of a physician. But for
healthy persons they are very pleasant, and in most cases
beneficial, provided they are not taken too often and that
one does not indulge in them too long at a time.
The terms sun-, mud-, sand-, and pine-needle baths are
self-explanatory. These are used in treating certain di&-
PERSONAL HYGIENE. 245
eases, and are supposed to do some good, especially in
rheumatic affections.
Clothing.
There is scarcely anything that can be said on this
subject with which almost every one of ordinary intelli-
gence is not in some respects conversant. According
to Dr. Poore, the main objects to be sought in clothing
the body are: " 1. To maintain the temperature and, by
preventing the loss of animal heat, to diminish to some
extent the demands for food. 2. To allow the chief heat-
regulating mechanism — z. e., the evaporation from the
skin — to proceed with as little hinderance as possible. 3.
To allow all muscular acts the greatest possible freedom,
and to avoid the compression of the body in so far as may
be possible. 4. To protect the body from heat, cold,
wind, and rain. 5. To disguise as little as may be the
natural beauties of the human figure/'1
The substances from which articles of clothing are
usually manufactured are wool, silk, cotton, linen, leather,
and furs, although almost everything that can possibly be
fashioned to suit the needs or fancies of the wearer is or
has been utilized for the purpose. Goods of all manner
and kind are woven from the first four substances men-
tioned, either singly or in combination one with another,
and felts are made from wool, hair, or fur, these latter
being made, not by weaving, but by an interlacing and
matting together of the fibres by pressure and rubbing.
In a general sense wool is probably the most valuable
of clothing materials, in that in a variable climate, or where
there are sudden changes of temperature, it is the safest for
1 Stevenson and Murphy : Treatise on Hygiene.
246 ^ MANUAL OF HYGIENE AND SANITATION.
the wearer to use. While, taking fibre for fibre, it prob-
ably does not vary so much from linen or cotton as a heat
conductor as is generally believed, it is usually woven in
such a way as to entangle large quantities of air in its
meshes, thus preventing either sudden cooling or heating ;
and beside, it is extremely hygroscopic, taking up water and
perspiration very readily and giving them off slowly, thus
reducing the cooling by evaporation to a minimum and
regulating the heat-dissipation of the body. All who are
at all subject to rheumatism or to such symptoms as are
dependent on sudden temperature changes should wear
woollen garments next to the skin the year round, varying
the thickness and weight, of course, to suit the season, and
children and others subject to digestive disturbances will
usually be greatly benefited by the constant use of woollen
(or, in case that is too heavy, a silken) band about the
abdomen.
As it is ordinarily woven, some persons cannot tolerate
wool next to the skin on account of its irritating proper-
ties. These latter are obviated, however, if the undergar-
ments be made of pure wool woven by methods similar to
that introduced by Dr. Jaeger, or of a mixture of wool
and cotton. The Jaeger method, by the way, provides for
the escape of moisture from the material and for the air
permeating freely through its interstices.
Silk is a good non-conductor of heat, and is almost as
hygroscopic as wool, so that it is good material from which
to make warm clothing. Its great natural beauty and the
facility with which it takes coloring matter also make it
desirable from an aesthetic stand-point, but its great disad-
vantage is its high cost. For those who cannot wear wool
next the skin and to whom the cost is no objection, silk is
an excellent material for undergarments.
PERSONAL HYGIENE. 247
Cotton is probably the most generally used for clothing
of all the fibres. It is hard and durable, is not as hygro-
scopic by far as wool, and is, above all, cheap, so that it
furnishes the -bulk of the clothing for the masses. If
smoothly woven and of a light color, it makes extremely
cool garments for warm climates or seasons. On the other
hand, if warm clothes are desired, the cotton must be
woven so as to have large air spaces in the fabric, the air
acting as an especially good non-conductor of heat and
preventing the lowering of the body temperature. Cotton
should not be worn next the skin by those subject to sud-
den temperature changes, nor during exercise, unless it is
changed in the latter case immediately after the exercise,
or some additional clothing is added to the body to prevent
too rapid evaporation and cooling.
Linen is valued for its purity of color when bleached,
and for its durability. It is more expensive than cotton,
but its hygroscopic and heat-conducting properties are
about the same as the latter. It is especially desirable for
making clothing for hot climates and for articles of dress
that are easily soiled and need frequent cleansing.
Furs provide extreme protection against the wind and
cold, both on account of the impermeability of the skin
and of the large quantity of air entangled in the fur itself.
Leather is utilized for foot-coverings, etc. , on account of
its durability, pliability, and practical imperviousness to
moisture, especially when oiled; and in cold countries is
also used for body garments, on account of its resistance
to the wind and the efficacy with which it keeps the body
surrounded with a layer of warm air.
With the possible exception of rubber, which is especially
useful for the protection which it gives from wet and wind
and rain, other materials from which clothing is made need
248 A MANUAL OF HYGIENE AND SANITATION.
not be mentioned here, because of the comparative rarity
of their use and their close resemblance to those already
mentioned. The value of any material for clothing pur-
poses, however, may be said to depend upon the slowness
with which it permits the passage of heat to or from the
body and the evaporation of water, the amount of air its
meshes contain, its impermeability to the wind, or else its
special adaptability to some special purpose.
Certain materials are manufactured from combinations
or mixtures of two or more of the four fibres first men-
tioned, and it sometimes become necessary to distinguish
these one from another and to determine the proportion of
each in the goods. This is done by microscopical exami-
nation, each fibre having its own peculiar characteristics,
and by chemical reactions. Some of these latter are as
follows: Wool and silk dissolve in hot liquor potassae or
sodse of a specific gravity of 1050, while cotton and linen are
not affected. Wool and silk are stained yellow by strong
nitric or picric acid; cotton and linen are not. Sulphuric
acid affects wool but little, slowly dissolves silk, and
changes cotton or linen into a gelatinous substance that is
colored blue by iodine. Hot concentrated zinc chloride
dissolves silk, but not wool; and copper dissolved in am-
monia rapidly dissolves silk and cotton, linen more slowly,
but only swells the wool a little.
Cloths are often fraudulently sophisticated in the process
of manufacture, and their value greatly lessened thereby.
Wool is mixed with "shoddy," which is made from old and
used woollen rags, torn asunder and then respun with an
addition of fresh wool; silk is heavily weighted with salts
of tin, iron, or with other substances, and cotton and linen
are stiffened and glossed with an excessive amount of
starch, white earth, or the like. Shoddy can be deter-
PERSONAL HYGIENE, 249
mined by the use of the microscope; the weighting of silk
by chemical reactions and solutions; and overstarching,
etc., of cotton and linen by washing and drying.
It will not be advisable here to go into the consideration
of the influence which the shape and style of the individ-
ual garments of ordinary use have upon health, for that
would require a much longer discussion than the present
space would allow ; but the general rule may be laid
down that each article of clothing should be adapted to
the peculiar needs and occupation of the wearer, and that
it should in no wise interfere with the proper develop-
ment, use, or physiological functions of any part of the
body.
When exposed to the sun's rays or to other sources of
radiant and incandescent heat, fabrics absorb heat, irre-
spective of the constituent materials, but in the following
order as regards color : White, light yellow, dark yellow,
light green, Turkey red, dark green, light blue, and black,
the latter color absorbing more than, and light blue almost
twice as much as white, the material in each case being
the same. In the shade the absorption depends more on
the material than on the color.
Lastly, it should be remembered that, as disease germs
are readily conveyed from place to place and from one
person to another by the clothing, and especially by that
which is hygroscopic by nature, care should be taken to
keep the garments in as cleanly and aseptic condition as
possible, to disinfect them whenever they have been ex-
posed to infection, and, for those who are much among the
sick or liable to infection, the use of smooth, closely woven,
non-hygroscopic over or outer garments that can be readily
cleansed, such as cotton or linen, is to be highly recom-
mended.
250 ^ MANUAL OF HYGIENE AND SANITATION.
Light.
The important influence of sunlight in the development
and maintenance of a healthful condition in all higher
organisms, both animal and vegetable, is well known by
every one; but as yet there is a lack of information as to
the exact physiological methods and processes which are
due to this great force. We know that for the plants
chlorophyll is the intermediary agent which largely assists
in the conversion of carbonic acid and the storage of carbon
in various compounds, and that the presence and action of
this chlorophyll are largely dependent upon the light-
supply; while for the animal kingdom, and especially for
the human race, it is evident that the effect of sunlight is
manifested more or less directly upon the blood and skin,
though the whole body quickly manifests a marked appre-
ciation of its presence or absence. But when this has
been said, there is little else that can be added as a matter
of positive information. No one knows just how the
pallid and anaemic child that has been reared in the shade
and dark can be converted into the tanned and ruddy
picture of health in so short a time, but the results are
unquestionable.
The subject demands much further study, and it may
not be out of place to indicate one or two directions in
which the investigation may, perchance, be wisely pursued.
In the first place, there has doubtless been too little
appreciation of the fact that the sunlight in its totality
has many other rays of force than those which manifest
themselves alone to our sense of sight. The existence of
the ultra-violet rays and the fact that these are more
powerful actinically than those of the ordinary spectrum
have been satisfactorily demonstrated, and the only ques-
PERSONAL HYGIENE. 251
tion is as to what the true power and influence of these
invisible rays may be. It is not certain as yet that some
of them, at least, are not closely related to the new mani-
festation of force discovered so recently by Rontgen, and
there is good reason to believe that the penetrative powers
of light as regards the human body are not yet fully
known or appreciated.1 Nor can we tell how much of
that power of the sun whose effects we feel and see is in
nature on that borderland between light and electricity
that is as yet so vague and unknown.
Again, the destructive effect of sunlight, and of light
from minor sources as well, upon the germs of disease and
other low forms of life, is now a matter of common knowl-
edge, though many are not aware that it has been proven
that this germicidal action of light is directly in relation
to its actinic power. Considering this, with the statements
of the preceding paragraph, may we not surmise that hostile
organisms, even in the deeper tissues, are overcome both
in this way and by the improved condition of the blood
due to the light, and that this helps to explain the good
results that follow the open-air treatment of many diseases
and abnormal conditions ? The tubercle bacilli are espe-
cially susceptible to its influence, and every one knows that
an abundance of sunlight is just as essential to the tuber-
culous patient as is plenty of good food, pure air, or proper
clothing.
More might also be said in reference to the possible and
1 Some experiments by the author and by numerous others seem clearly to in-
dicate that some of the radiant energy from the sun, and in lesser degree from
other sources of light, is able to penetrate substances hitherto considered opaque
and to produce phenomena similar to those due to the Rontgen ray. Conse-
quently, if the experiments referred to are well founded, the penetrative ability
of this energy, as regards the human tissues, would seem to be more than prob-
able.
252 ^ MANUAL OF HYGIENE AND SANITATION.
probable chemical activity of the light in and upon the
metabolic processes of the animal body; but as there is
still the uncertainty of hypothesis and theory, it may be
wiser to simply leave the foregoing suggestions as food for
thought and incentives to further research and investiga-
tions.
CHAPTER IX.
SCHOOL HYGIENE.
IT might have been remarked in the chapter on Per-
sonal Hygiene that the best time for applying and observ-
ing the laws of hygiene is in the days of childhood and
youth, for then the whole organism is plastic and yields
readily to both external and internal impressions and
forces.
This being so, the great influence of the factors common
to school life may be readily conceived, and inasmuch as
the average child will be subject to them for a large part
of from eight to ten or more years, the importance of a
study of school hygiene will not be denied. It concerns
the parent, the physician, and the citizen, and its investi-
gations must consider the personal hygiene of the scholar,
the condition of his health, his habits, the amount of
work done, the sanitary environment and requirements of
the school-room or building, the furniture, the ventilation
and heating, and the influence of all these upon the indi-
vidual's state and development.
Next to the scholar himself and his parents, these mat-
ters are of especial interest to the physician, for, beside
being one, who from his special training and education is
often called to act upon school committees and boards of
education, he has to treat many disturbances of health in
the young which have their origin or cause in the harmful
or insanitary conditions of school life.
There are disturbances to which all children are subject,
254 A MANUAL OF HYGIENE AND SANITATION.
whether in school or out; but a special class are markedly
influenced by school life or work, and to these abnormal
conditions we may give the term "School Pathology. "
Of some of these overwork is the cause; others are set up
by other factors.
Overwork, coupled with depressed vitality, may give rise
in children to one or more of the following troubles : Dys-
pepsia, headaches, nervous derangements, chorea, epilepsy,
neurasthenia, backaches, menstrual disorders, and, in some
cases, consumption. On the other hand, bad arrangement
of seats and desks, improper location of windows, black-
boards, etc. , may cause spinal and other physical deformi-
ties, defective eyesight, etc. Of the first class, even where
the amount of work may not seem or may not really be
too much for the capacity of the child, worry about rank
or over an approaching examination may have a harmful
effect upon a nervous temperament. This is especially so
if the examinations come at the end of a spring term,
when the scholars are all more or less worn out and debili-
tated. The forcing process should be avoided as far as
possible, and if grades are to be given at all, they should
be as much as possible for the work and attendance during
the term, and not so much for the actual work done at
examination time.
Moreover, young children should not be kept in school
for too many hours in the day, nor should the school be
looked upon by parents as a place to which to send chil-
dren to keep them out of the way and from mischief.
Edwin Chadwick has shown that a child from five to seVen
years can only attend to one subject for about fifteen min-
utes; one from seven to ten, for twenty minutes; from ten
to twelve, for twenty-five minutes, etc., and that the length
of individual lessons and likewise the total day's work
SCHOOL HYGIENE. 255
should be arranged accordingly. The very early years of
school life should be given to inculcating correct habits of
attention and of morals and to training the will and power
of concentration, rather than to the teaching of any special
knowledge.
But it is probably the work attempted outside after
school hours, and not the actual work done in the
school, that is most responsible for the breaking down
of health, especially in older scholars. In Cleveland, in
1881, of 186 girls in the high school, 29 per cent, of those
who studied less than two hours, 70 per cent, of those
studying from two to four hours; 93 per cent, of those
studying from four to six hours, and 100 per cent, of those
studying over six hours daily out of school, had poorer
health while at school. Of these same girls, the percent-
ages of those whose health was " very poor while at
school/ ' dividing them the same way as regards over-
work, were respectively 14 per cent., 40 per cent., 66 per
cent., and 100 per cent. This loss of health was attributed
by the parents to stair-climbing, irregularity of meals,
worry about rank and examinations, etc., but Dr. Goodell
says: (( So commonly do I find ill health associated with
brilliant scholarship, that one of the first questions I put
to a young lady seeking my advice is, ' Did you stand
high at school ?? ' Another writer says : ' ' The effects of
anxiety are worse than carrying heavy loads."
While a child is at school its mind should not be wea-
ried by outside tasks, as music or painting lessons, nor the
body weakened by social dissipations, late hours, and indi-
gestible food. Girls are more susceptible to disturbances,
and are more subject to them, because they are more will-
ing to undertake extra or double work than boys, and
because they are more ambitious and worry more about
256 A MANUAL OF HYGIENE AND SANITATION.
rank. In all children the obtaining of good health and
a sound constitution is of the first importance. Youth is
the time for gaining health, not for losing it; for building
up sound bodies and constitutions, not for breaking them
down, and school life should always have the former as
one of its greatest ends. Of what use is all the learning
one may gain before the age of eighteen, if there be no
strength to use it afterward in the battle of life ?
School-life is sometimes responsible for dyspepsia by
interfering with the regularity of meals, the children miss-
ing the midday meal and having to depend upon a meagre
lunch, often of sweets and indigestible food. This is espe-
cially important when the rest of the family dine at noon,
and there is only a light meal served in the evening.
Again, many habitually lose their breakfast through fear
of being late, or else bolt the food without masticating it,
and gulp down hot coffee or tea before starting on a run
for school. But often the loss of appetite is due simply
to lack of fresh air and proper exercise. Such dyspepsias
are to be treated by attention to the foregoing points rather
than by medicine.
Headache is a common disturbance among school chil-
dren, and may be due to any one of several causes, among
which are overwork — producing irritability and disturb-
ances of cerebral circulation — bad air, eye-strain, etc. The
eyes should always be examined when headaches are per-
sistent, and any defects corrected by proper glasses. Asso-
ciated with the headaches frequent bleeding from the nose
may occur, and should not be overlooked, as it may in-
dicate circulatory disturbance.
One of the most common symptoms of nervous derange-
ment is sleeplessness or restless sleep, and this condition
should give warning that something is wrong. Dr. Folsom
SCHOOL HYGIENE. 257
says: "I doubt whether there is an exaggerated preva-
lence of manifest or well-marked diseases of the nervous
system among school children. If due to the school- drill,
my impression is that they come for the most part later in
life, after the children have left school, and because of
constitutions weakened during school years, instead of
strengthened as they should be." Children subject to
chorea or epilepsy should not attend school, not only for
their own sake, but for that of the other children, who
may be unduly affected by their nervous manifestations.
They should be educated quietly and cautiously, with
proper treatment and plenty of outdoor life. Neurasthe-
nia or general break-down may occur, usually from over-
work, and especially among young women. It may come
on unexpectedly after the examinations, when the strain
and excitement are removed. Menstrual disorders are also
apt to occur among girls that are being overworked men-
tally, and we ought to remember that at the time this
function is developing the system is undergoing a heavy
strain. Also, to certain women rest from customary work
is necessary at the time of the periodical recurrence, and
excuses for absence at this time ought to be freely granted.
It has been said that " girls get through as much work as
boys, working in their own way."
The development of consumption may be due to the
school-life, though it is hard to say how frequently this is
the case. Bad air and overwork are both important
factors in its production, and if these are forced on under-
fed or predisposed children the disease may be provoked.
" In a consumptive family the steadfast rule should be
that the mind be wholly subservient to the body's welfare."
The main cause of spinal and other deformities and
defective eyesight is apt to be found in faulty construction
17
258 A. MANUAL OF HYGIENE AND SANITATION.
of seats and desks, improper location of windows, etc.,
though excessive work or strain may maintain a low vitality
and act as a predisposing condition. The latter point is
shown by the fact that spinal curvatures are more preva-
lent in those especially prone to weakness of the muscles,
as women and girls.
But no desk or seat will remove original weakness of
muscle as the one important predisposing condition, and
children cannot be made strong by supports. <e Spinal
curvature is not only a product of low vitality, but does
harm by permanently fixing vitality at a low standard. "
Bad seats and desks not only cause spinal deformities, but
help to cause defective eyesight by making the scholar
hold the book too near the eyes and by making him bend
his head so that the circulation of blood is impeded and
ocular congestion favored. However, no seat can be de-
vised in which a child will maintain a correct or " normal "
position for any length of time, as this is an impossibility
for young children; but the true aim should be to furnish
a seat in which one will naturally assume the correct posi-
tion after having temporarily taken any other. " Move-
ment is a child's way of resting; rest is a kind of work,
to be taught by degrees. " Seats should have backs to
prevent fatigue, but a comfortable back gives support to
the lower part of the spine rather than to the shoulders
and upper part of the spine. Many foregin authorities
advise seats with backs only high enough to support the
lower part of the spine, and low enough for the scholar to
rest his elbows upon them while studying. The following
points, suggested by Dr. Lincoln, are worth noting : " 1.
The chair is often too high for young scholars. The most
convenient plan may be to provide footstools. 2. The seat
from back to front ought to be long enough to support the
SCHOOL HYGIENE. 259
whole thigh. A more or less spoon-shaped hollow in the seat
is commonly thought desirable. The curve of many settees
is such as to produce pain at the point where the tuberosi-
ties of ischium rest on the wood; the support is there not
wide enough. 3. Seats must have backs. The straight,
upright back reaching to the shoulders is bad; a straight
back, slightly tilted, is not bad. American seats are com-
monly curved, with curved backs. 4. The edge of the
desk should come up to, or overlap, the edge of the seat.
The recognition of this fact is a recent discovery. 5. Most
of our best desks are too high relatively to the seat, doubt-
less to prevent the pupil from stooping. Something is
gained in convenience of reading by this plan, but it in-
terferes with correct positions in writing. The elbows,
hanging freely, should be only just below the level of
the lid." For near-sighted children the higher desk
may be a necessity in writing; if the desk is made low a
portable writing-stand may be placed on top of it when
necessary.
Windows on only one side of a large school-room may
not give sufficient light for the desks most remote from
them. Consequently, there should be windows on two
sides, preferably adjoining ones, of large school-rooms.
The windows should be at the back and to the left of the
scholar, thus giving the best light upon the desk for either
reading or writing. They should not be placed in front of
the scholars, as the continuous light and glare is very try-
ing and injurious to the eyes. They should extend almost
to the ceiling and have square tops, to admit of as much
light as possible. Blackboards should have a dead-black
surface, not a glossy one, and should be on the sides of
the room on which there are no windows. Walls should
be of a neutral tint, not glaring white.
260 A MANUAL OF HYGIENE AND SANITATION.
Construction of School-houses. The principles
already given as to ventilation, heating, water-supply,
etc., apply here as elsewhere. From 1800 to 2500 cubic
feet of fresh air should be supplied to each scholar per
hour. In cold weather this should, of course, be satis-
factorily heated. The air-ducts, both inlets and outlets,
must be large enough to change the air without causing
injurious and uncomfortable draughts; and these ducts
should be as short and free from bends as possible, or better,
the rooms should open into the supply and exhausts shafts
directly. The air may be warmed either by steam or
hot-water coils or by a furnace, though preferably by the
former, to avoid " baking " the air, and also preferably by
the indirect system. There is no objection to having addi-
tional heating apparatus in the school-room, provided it is
guarded so that the scholars may not be accidentally
burned. Any system that will give a sufficient supply of
fresh air properly heated will of necessity be more expen-
sive than the old way of not ventilating at all except by
opening the windows at recess time, but experience shows
that the increase in expense is not so very great, as so
much heat is lost by opening the windows in this way,
and the benefit to the children more than compensates for
the additional outlay. Country schools may be heated
by stoves surrounded by sheet-iron drums, and ventilated
with fresh air brought in from without near the bottom
of the stove. Passing up between the stove and drum
the air is warmed and gives good ventilation without
chilling or draught. As great a length of stovepipe should
be exposed as possible, to get the full benefit of the heat
from it.
The school-house should be on dry and well-drained
soil, as dampness is not only depressing to all constitu-
SCHOOL HYGIENE. 261
tions, but is an important factor in the causation of phthisis
and strumous diseases. There should not be too much
shade about, and as many rooms as possible should have
sunny exposures. If the sun is annoying during the ses-
sion, it may be excluded by inside blinds or shutters, but
we must not lose sight of its helpful influence in the de-
struction of bacteria and purification of organic matters.
Basements of school-houses should be well lighted, water-
tight and dry, and should be kept scrupulously clean, that
moisture and noxious gases may not be drawn into the
rooms above. If properly arranged and cared for^ they
may be used as play-rooms in bad weather when it would
be unwise to send the scholars out of doors.
The water-supply should be free from all impurities and
as good as can be had. In the country, if from a neigh-
boring farm-house spring or well, it may be contaminated
by leakage from cesspools and barnyards. Or the school
water may be taken from a neighboring spring or stream
which is receiving contamination from the school-house
cesspool or other sources. For this reason, teachers should
be taught to make the test for chlorides and the reason
for it, and should make this test frequently. If cause for
suspicion arises the use of the water should be stopped at
once.
Water-closets and urinals, where in use, should be kept
clean by a competent janitor, and the principal or head-
teacher should see that this is done. In the country, the
pail or earth-closet system should be substituted for the
usual privy-vault or cesspool, and it should be the duty of
some one apart from the teacher, regularly appointed and
paid by the school directors of the district, to see that
removals are made at proper intervals; the teacher should
maintain supervision over the daily condition of affairs.
262 A MANUAL OF HYGIENE AND SANITATION.
If possible, the out-houses should be connected with the
school-house by covered ways, that the children may not
be exposed in inclement weather; but these ways should
be open or else constantly ventilated by open windows on
either side. Cesspools should be at least fifty feet distant,
and should drain away from the school-house.
Ample provision must be made for the rapid escape and
for the safety of scholars and teachers in case of fire or
panic. Fire-drills should be regularly practised in all
schools of two stories or more, and presence of mind incul-
cated, that emergencies may be met with safety. The
comfort of the child should not be forgotten in the con-
struction of the school-house, though preservation of
health is the main aim.
School Quarantine. As certain diseases are conta-
gious, it is necessary that school authorities have, a right
to forbid the attendance of such persons as have been
exposed to infection until all danger of transmitting the
disease to others is passed. This power is usually, how-
ever, exerted only in the case of those diseases most dan-
gerous to life and health, though the stringency of the
regulations varies at different places. Smallpox, scarlet
fever, diphtheria, measles, and even whooping-cough ought
always to be quarantined, and it would be better to keep
children out of school who are afflicted with minor dis-
eases of this class till all danger of infection is over,
as it is only by rigid measures like this that we may
finally be able to wipe those maladies out of existence.
Local boards of health should make and enforce rules
looking to the prevention of the spread of the graver
contagious diseases, and should, when necessary, close
schools and school- buildings till all danger is past. Dr.
Lincoln gives the following as a system of general regu-
SCHOOL HYGIENE. 263
lations: " 1. Persons affected with diphtheria, measles,
scarlet fever, or smallpox (varioloid) must be excluded
from the schools until official permission is given by the
board of health for their readmission. 2. Persons living in
a family or house where such a case occurs are also excluded
until similar permission is given. 3. This permission is
not to be given until sufficient time has elapsed since the
occurrence of the last case to insure safety, nor until the
premises have been disinfected under the direction of the
board of health. 4. If a child suffering from one of
the above diseases attends school, the premises of the
school must be disinfected under the direction of the board
of health before they are used again. 5. Physicians,
teachers, school officers, and school "children knowing of
such cases of disease should at once report them to the
board of health. 6. The board should also notify the
school authorities of all such cases. 7. Notice must be
sent to the family by the school authorities, acting con-
jointly with the board of health."
Children having had one of the above-named diseases
may return to the school with safety after the following
periods: " Scarlet fever, six weeks from date of rash, pro-
vided desquamation and cough have ceased. Smallpox
and chicken-pox, when every scab has fallen. Whooping-
cough, after six weeks from commencement of whooping,
provided the characteristic spasmodic cough and whooping
have ceased, or earlier if all cough have passed away.
Diphtheria, not less than three weeks, if convalescence
is completed; there being no longer any form of sore
throat nor any kind of discharge from the throat, nose,
eyes, ears, etc., nor any albumin uria." Rules and regu-
lations like the above, when promulgated, " should have
the force and authority of law, and should be enforced, if
264 A MANUAL OF HYGIENE AND SANITATION.
necessary, by the entire power, including school officers,
etc., of the State/' It is to be hoped that we shall soon
have a means of inoculating persons against all contagious
diseases, as we now do against smallpox. At present
boards of health and school boards should insist on the
vaccination of all school children. In Illinois, from 1880
to 1883, .the deaths from smallpox among un vaccinated
children were 48 per cent.; among the vaccinated, only
0.9 per cent. In this city all who desire it are vaccinated
free of charge by the vaccine physicians, and it is com-
pulsory for all school children.
Regulations similar to the following, suggested by
Lincoln, should be in force in every school district :
(( Every child entering the public schools must show a
certificate from some reputable physician, giving name,
age, residence, approximate date of vaccination, date of
examination, result of examination, the last two to be of
the physician's own knowledge. The fact of vaccination
must be entered on the school record and on lists for pro-
motion and transfer. The school authorities shall annu-
ally report the number of those not protected to the State
Superintendent of Education. School authorities may
order the exclusion of non-protected persons, after suffi-
cient notice, where they think the measure required for
the public health. He- vaccination at the age of fifteen
may be required under similar circumstances. Those
unable to pay should be furnished with free vaccination
by the school authorities. A physician's certificate of
protection by a previous attack of smallpox is equivalent
to a certificate of vaccination."
Contagious ophthalmia is a disease often prevalent in
institutions and occasionally in primary schools, and re-
quires great care to prevent its invasion and spreading, as
SCHOOL HYGIENE. 265
well as to effect a cure. Those afflicted with it should be
quarantined until there is no further discharge or till the
granulations on the inner surface of the eyelids have disap-
peared. Enfeebled health and poor and insufficient food
favor its development, but the chief means of contagion
is by the use of the same wash-basins and towels by a
number of children.
School children should not be allowed to attend the
funerals of companions dead of a contagious disease, nor
should funerals be allowed in school-houses under any
circumstances, owing to the effect on the thoughts and
sensibilities of nervous children.
Boarding-schools and institutions should have an in-
firmary where contagious diseases may be isolated, and
should make that isolation as complete as possible from
other scholars and inmates. At the beginning of a term it
may be well to subject any who have been exposed to conta-
gion to a delay until the probable period of incubation for
the special disease is passed, the period dating from the time
of exposure. With the above precautions it will rarely
be necessary to close a school, unless a disease be markedly
epidemic and malignant.
CHAPTEK X.
DISINFECTION AND QUARANTINE.
As has already been stated, disinfection is that part of
prophylaxis which has to do with the destruction or modi-
fication of the exciting causes of disease, and we may
accordingly define a disinfectant as " an agent capable of
destroying the infective power of infectious material."
Moreover, as with our present knowledge we are practi-
cally limited in the use of disinfection to the infectious
diseases only, a disinfectant must also be a germicide.
Theoretically, it should also have the power of destroying
the poisonous properties of the toxins which the disease
germs produce, and which create the characteristic symp-
toms of the specific diseases; but whether all good disin-
fectants have this power is by no means proven, and is
not altogether essential, since by killing the germs we
check the further production of the toxins, and disinfect-
ants are mainly used not so much to cure or stop a disease
in a patient as to prevent its extension to others. But, in
a popular sense, the term disinfection is given a wider
meaning than is above indicated, including not only the
use of antiseptics and deodorants, but often the actual re-
moval of filth and all matters favorable to the growth or
spread of disease germs. It is needless to say that these
latter may be part of the prescribed duties of a disinfector,
but are not the essential functions of a disinfectant.
It will be well here to make the distinction between
disinfectants and antiseptics and deodorants, as the terms
DISINFECTION AND QUARANTINE. 267
are often wrongly used interchangeably, and there is a
common belief that whatever is a deodorant or an anti-
septic is also a disinfectant. An antiseptic is an agent that
retards or arrests bacterial growth and the consequent pro-
duction of toxins or ptomaines, though it does not neces-
sarily kill the micro-organisms themselves; and though
some antiseptics are germicidal, others are not and, there-
fore, as a class they cannot be considered or used as dis-
infectants. But, on the other hand, " agents which kill
bacteria in a certain amount prevent the multiplication of
the latter in culture fluids, when present in quantities
considerably less than are required to destroy vitality.7'
So, a diluted germicide may act as an antiseptic and may
be used therefor. For instance, chlorinated lime, which
is a good disinfectant in solutions of proper strength, may
arrest further bacterial growth or action in a mass of
sewage or filth and prevent the latter acting as a culture-
medium for disease germs, even though the agent be
totally inadequate in quantity to kill all the micro-organ-
isms' present. In the same way, it may act as a deodorant
— which, by the way, is an agent that simply removes or
destroys offensive odors, and is not necessarily either a
disinfectant or an antiseptic — both by checking the further
action of saprophytic bacteria and the formation of putre-
faction odors, and by actually decomposing and oxidizing
those of the latter already formed.
In practical disinfection it is also well to remember that
while masses of dead organic matter may not in some cases
contain disease germs and may be even hostile to them, in
general the reverse of this is more likely to be true, and
decaying matter often furnishes a good field for the increase
of pathogenic organisms. Moreover, the noxious gases
given off to the air and the poisonous products added to the
268 ^ MANUAL OF HYGIENE AND SANITATION.
drinking-water from such masses may also do much harm
by depressing the system, lowering the vitality, and acting
as predisposing conditions to the incurrence of such filth
diseases as cholera, yellow fever, typhoid and typhus fever,
diphtheria, etc. ; and when time or opportunity do not
permit of the removal of such dangerous accumulations,
their power for harm should be checked permanently or
temporarily by the use of suitable disinfectants or antisep-
tics.
But when we are actually dealing with disease germs,
disinfection, to be trustworthy, must be carried out to the
best of our ability with the means at our command and
with strict attention to the minutest details. " There can
be no partial disinfection of infectious material ; either its
infectious power is destroyed or it is not. In the latter
case there is a failure to disinfect/7
This is because the undestroyed living bacteria still have
the power of reproduction, and may, within a very short
time under favorable circumstances, equal or even exceed
the number that was present before the unsuccessful disin-
fection was attempted.
The knowledge as to the efficacy of any substance as a
disinfectant is obtained from the accumulated experience
of practical sanitarians and from experiments on suscep-
tible animals and in culture media. with infectious matter
treated with presumably disinfecting agents. The knowl-
edge gained must stand the test of scientific deduction,
and a substance is not a disinfectant simply because, in
one given case, infection did not occur after its use. To
be of value the deductions must be made from considerable
accumulated and practical experience. " Negative evi-
dence should be received with great caution ;" but if the
experience of practical sanitarians is confirmed by careful
DISINFECTION AND QUARANTINE. 269
culture and inoculation experiments, our knowledge of
the value of any agent becomes more definite and our
practical work more exact. From these inoculations and
experiments it has been found that the infectious germs of
different diseases differ in their power to resist the different
disinfectants; but nevertheless it may be stated that " in
the absence of spores, a disinfectant for one is a disinfec-
tant for all." Consequently, we are able to simplify and
classify the agents at our disposal, and to make more
effectual use of them. Note that there is nothing in the
tests mentioned to disprove the efficacy of disinfectants,
whatever the nature of the infecting material, and whether
the germ theory be accepted or not.
Some agents that are powerful against all other organ-
isms completely fail in destroying the vitality of spores,
and thus our list of disinfectants available in all cases is
still further reduced. In the case of a disease germ that
does not produce spores, as that of cholera, and probably
also of scarlet fever, smallpox, yellow fever, etc., agents
may be used that are really powerless against spores, but
in doubtful cases only those should be used that have the
power of spore destruction.
We may classify the disinfectants of which we may
make practical use as thermal or chemical, though there
are undoubtedly certain secretions and tissues in the body
which have the power of destroying infective matters,
giving each person more or less immunity against certain
diseases, and these we may term physiological disinfectants.
Of the thermal disinfectants fire is the most efficacious,
as it destroys all organic matter, but it can only be used to
destroy articles of little value or that cannot be safely
disinfected in any other way. For instance, it will usually
cost more than they are worth to disinfect thoroughly by
270 A MANUAL OF HYGIENE AND SANITATION.
other methods old mattresses that have been used in an
infectious case, so it is best to burn them.
All things considered, steam is probably the most efficient
disinfectant, as it is cheap, easily used and manipulated,
and is less liable to injure the articles to be disinfected.
We employ it under pressure, when its temperature is
correspondingly increased, or in the streaming state (live
steam), the latter being almost as efficient as the former,
FIG. 35.
Steam sterilizer for small articles.
but requiring a little longer time. For instance, steam at
240° F. is said to kill the most resistant spores almost
instantly, and streaming steam at 212° F. will probably
produce the same effect within thirty or forty minutes.
Special apparatus for disinfecting large articles by steam
is now or doubtless soon will be established in every large
city by the municipal authorities and others, as a sanitary
precaution and to prevent the spread of epidemics.
DISINFECTION AND QUARANTINE.
271
In the absence of spores, bacteria are killed by hot water
even below the boiling point, and it is probably safe to say
that boiling for half an hour will kill all known disease
germs, especially if a little washing soda be added to the
water; although spores of certain harmless bacilli are said
to have resisted boiling for several hours. In the absence
of chemical disinfectants, boiling water may be used to
FIG. 36.
Steam disinfecting chamber for clothing, bedding, and other large articles.
disinfect excreta, etc., and all clothing from the sick or
the attendants upon the sick should be well boiled before
washing, whether other disinfectants are used or not.
Dry heat is far less penetrating than moist, and must,
accordingly, be used at much higher temperatures and for
a longer time. At 300° F. it will require three or four
times as long to do what steam at 212° or 220° F. will
do, and, moreover, it is very apt to injure clothing or other
272 A MANUAL OF HYGIENE AND SANITATION.
organic materials exposed to it at high temperatures for so
long a time as is necessary. Consequently, it is only to be
used to disinfect articles that would be spoiled by moisture
or chemicals, and even then it is better to employ the
" fractional ' ' method — i. e., exposure to high tempera-
tures for short periods only, but for a number of times,
with sufficient intervals between the exposures to allow
the development of any spores that may possible be
present.
Regarding the chemical disinfectants, it must be remem-
bered that it requires a certain amount of each to disinfect
a given quantity of bacteria, and also that, with all disin-
fectants, time is an important element, and none act abso-
lutely instantaneously. Heat, however, facilitates and
increases the rapidity of action of the chemical disinfect-
ants.
Chlorinated lime (chloride of lime) is one of the best and
cheapest disinfectants. It should contain at least 25 per
cent, of available chlorine, should be kept covered from
air and moisture, and fresh solutions should always be
made as needed. Its power is due to hypochlorite of
lime, which is freely soluble in water and readily decom-
poses in contact with organic matter, giving up chlorine
gas — a most powerful disinfectant. " Germs of all kinds,
including the most resistant spores, are destroyed by this
solution ; but it must be remembered that the disinfectant
itself is quickly decomposed and destroyed by contact with
organic matter, and that if this is present in excess, disin-
fection may not be accomplished, especially when the
germs are imbedded in masses of material which are left
after the.hypochlorite of lime has been all exhausted in the
solution/7 Labarraque's solution, a solution of chlorinated
soda, is a fair disinfectant, but does not keep well, and
DISINFECTION AND QUARANTINE. 273
chlorinated lime is equally as good and much cheaper.
However, the soda solution has scarcely any diagreeable
odor, and makes a pleasant disinfecting bath for the person.
It must contain at least 3 per cent, of available chlorine.
Bichloride of mercury is one of the best germicides that
we have, and is effective in comparatively weak solutions.
It corrodes metal, and so cannot be used to disinfect waste-
pipes, etc. ; and it combines with and coagulates albumin,
which interferes somewhat with its action. This coagula-
tion is prevented to a degree by the addition of tartar ic
acid to the disinfecting liquid. The same result is said to
be obtained if one part of peroxide of hydrogen (fifteen
volume solution) be added to three parts of a corrosive
sublimate solution of any strength. But for the above
reason it is best not to use corrosive sublimate in disin-
fecting excreta, as these always contain more or less albu-
min, and a lime solution is better and more certain. As
carbolic acid also coagulates albumin, it is not well to use
it for a like purpose.
Carbolic acid is effective in the absence of spores, and,
according to Koch, should have first place in disinfection
against the cholera germ. It is of doubtful value, how-
ever, in cases of typhoid fever, as it is said that the typhoid
bacilli can be cultivated in a medium containing J per
cent, of carbolic acid. Solutions should always be made
by first dissolving the acid in glycerin, and should usually
contain 5 per cent, of acid.
Copper sulphate is a fairly good disinfectant in the
absence of spores; is a deodorant, and is cheap. It may
be combined with bichloride of mercury to color the solu-
tion of the latter and to get the benefits of its deodorant
powers, which the corrosive sublimate does not have. Use
may be made of the following formula: Corrosive subli-
18
274 A MANUAL OF HYGIENE AND SANITATION.
mate (bichloride of mercury), 4 ounces; copper sulphate,
1 pound; water, 1 gallon.
Zinc chloride is a good antiseptic and deodorant, but not
a very powerful disinfectant. A 5 or 10 per cent, solu-
tion will kill germs without spores.
Calcium hydrate, when mixed with water to make a thin
whitewash (milk of lime), is said to be a good disinfectant,
especially for excreta, etc., and is one of the cheapest and
easiest to obtain. It should be added to the infectious
matter in excess or until the mixture is decidedly alkaline,
and will require from one-half to two hours to disinfect
thoroughly.
An extremely valuable disinfectant for local or topical
applications to the person is hydrogen peroxide or dioxide
(H2O2). It is harmless, even when taken internally; is
effective in comparatively weak solutions, and is especially
active in the destruction of pus organisms. It is usually
supplied in the form of a 15 per cent, solution in water
and, at present, only its high cost prevents its more ex-
tended use.
Until the discovery, in 1892, of the great disinfecting
power of formaldehyde or formic aldehyde by Trillat and
Aronson, about the only gaseous disinfectants of practical
value were chlorine and sulphur dioxide.
Of these, chlorine is the most powerful and efficient,
but the distressing and oftentimes serious symptoms which
it produces when accidentally inhaled, and the bleaching
effect that it has upon many articles, have both tended
to prevent its common employment. Like the sulphur
dioxide, it acts best in the presence of moisture, and, there-
fore, steam should be simultaneously introduced and liber-
ated in the room or enclosure in which either of these
disinfectants is used. Sufficient chlorine for 1000 cubic
DISINFECTION AND QUARANTINE. 275
feet of space may be generated by carefully pouring two
fluidounces of strong sulphuric acid and three fluid-
ounces of water, previously mixed and cooled, upon eight
ounces of sodium chloride (common salt) and two ounces
of manganese dioxide. The acid must be added to the
water little by little and with care, and the salt and man-
ganese should be in an earthen vessel upon a bed of sand,
to prevent injury to the floor or carpet.
Sulphur dioxide (SO2), though not so positive in its action
as chlorine, is more frequently employed on account of the
lesser risk and trouble connected with it. It probably
kills germs not containing spores if sufficiently concen-
trated and in the presence of moisture, and is, therefore,
useful in the fumigation of rooms and of articles that
cannot be subjected to steam heat or chemical solutions.
But it will bleach or tarnish many articles, and for this
reason and the fact that it is much inferior to formalde-
hyde, it will hereafter probably be almost entirely sup-
planted by the latter whenever that can be obtained.
To secure sufficient concentration at least three pounds
of sulphur should be burned for every 1000 cubic feet of
space, care, of course, being had that there is no risk of
igniting the floor or any articles in the room.
Formaldehyde (formic aldehyde), both in its gaseous state
and in solution, is undoubtedly one of the best and most
efficient disinfectants now in use. It has considerable
penetrating power, although less than steam or than was
claimed for it at first by its more enthusiastic advocates,
while for surface disinfection it acts almost immediately.
It is, therefore, much better in this respect than the chlo-
rine or sulphur dioxide already mentioned, and where it is
properly used, only such articles as bedding, mattresses,
and pillows, that can be better treated with steam, need be
276 A MANUAL OF HYGIENE AND SANITATION.
removed from an infected apartment. Clothing, rugs,
hangings, etc., that can be freely exposed to it are quickly
sterilized. Another important feature is that it does not
act destructively on either clothing or furniture, and that,
although it is quite irritating to the conjunctivas of the
eyes and to other mucous membranes when concentrated,
it is virtually non-poisonous.
Formaldehyde is readily absorbed and held in solution
by water to the extexnt of 40 per cent, by weight of the
latter, but as soon as this proportion is exceeded there is a
polymerization of the gas and a solid (paraformaldehyde
or paraform) is precipitated, which is only resolved again
into formaldehyde at a temperature of 275° F. The 40
per cent, solution is practically identical with the prepa-
ration which is commercially known as formalin, and
has usually an addition of 10 per cent, of methyl alcohol
to further guard against precipitation. Very weak solu-
tions (1 or 2 per cent.) of the gas are still effectively dis-
infectant, while its virtue as an antiseptic persists even
when the dilution is carried to a remarkable degree.
One peculiar effect of the solutions is that of rendering
connective tissue and all gelatinous substances insoluble
in either hot or cold water, and it is probably to this that
its germicidal activity is largely due, since the food supply
of the bacteria, if not the substance of the latter them-
selves, is partly of this nature. For the same reason it
hardens and disagreeably roughens the skin, which tends
to prevent its use for topical applications.
Several methods have been devised for the production
or liberation of formaldehyde in rooms and buildings in
such volume as positively to secure both surface and pene-
trative disinfection. Of these, the best results seem to
have been obtained where a solution of the gas, such as
DISINFECTION AND QUARANTINE. 277
formalin, is heated and vaporized. For instance, in Tril-
lat's apparatus the solution is heated, calcium chloride
also being added to further insure against the precipitation
of paraform. A simpler device, called a regenerator,
allows the solution to flow in a fine stream through a
copper coil heated to redness by a flame beneath, the gas
and vapor then passing directly into the room in a super-
heated and effective condition. Both of these methods
have the advantage that the apparatus may be operated
* FIG. 37. FIG. 38.
Trillat's autoclave or apparatus for Regenerator for vaporizing for-
liberating formaldehyde. maldehyde solutions.
outside of the room to be disinfected, and the action ac-
cordingly controlled; also that the amount of gas liberated
depends directly upon the strength and quantity of the
solution evaporated.
In the Schering method, the solid paraform is heated in
a receptacle over an alcohol lamp, the volume of resulting
formaldehyde depending, of course, upon the amount of
paraform used. This method has yielded some excellent
results experimentally, and is of special value in disinfect-
278
MANUAL OF HYGIENE AND SANITATION.
ing small rooms, closets, and sterilizing cases made for
instruments, dressings, etc.
Probably the cheapest and most common form of appa-
ratus is that which has been devised, in the form of a
portable lamp, to develop the gas directly by the oxidation
of methyl alcohol, the vapors of the latter being made to
pass over or through tubes or coils of heated metal, and to
be thus converted into the disinfectant gas. Considerable
formaldehyde can doubtless be produced in this way, but
FIG. 39.
FIG. 40.
Schering's lamps for volatilizing parafonn.
the amount at any time is uncertain and the results indefi-
nite, since part of the alcohol vapors are polymerized and
part are further oxidized into compounds such as carbon
monoxide and carbon dioxide. Therefore this method is
only to be advised for comparatively small apartments or
enclosures, and not where certainty of disinfection is
important.
Whenever formaldehyde is employed as a gas all the
apertures in the room should be carefully and tightly
closed, since, having the same specific, gravity as the air,
its diffusion takes place rapidly. Moreover, after a suffi-
DISINFECTION AND QUARANTINE.
279
cient volume of the gas has been liberated, it should be
allowed to act as long as possible, preferably for twenty-
four hours at least, since the time element is just as impor-
tant a factor with this as with other disinfectants.
Lastly, the gas is an excellent deodorant, combining as
it does with the effluvia from decomposing substances to
produce odorless compounds. Its odor, in turn, may be
quickly dissipated from a room by evaporating a little
ammonia therein.
The following table of Koch and Jaeger is added to
show the comparative disinfectant strength of some sub-
stances occasionally used for the purpose:
Disinfectant.
Bichloride of mercury
Silver nitrate . . . .
Acid, hydrochloric . . 2
{2
15
Ferrum chlorate ... 5
Calcium chloride . . 5
Potass, permanganate 5
Caustic Ume . . {«™l
Strength.
1 to 20,000
1 to 1,000
1 to 12,000
1 to 4,000
1 to 2,500
2 to 100
100
100
100
100
100
100
100
Acid, carbolic
Formaldehyde
(K. Walter).
to 1,000
10 to 100
1 to
3 to
100
100
Objects submitted Time required
to experiments. for destruction.
Anthrax spores. 10 minutes.
Anthrax spores.
Anthrax spores.
Cholera and typhoid
Diphtheria.
Anthrax spores.
Anthrax spores.
Anthrax spores.
Anthrax spores.
Anthrax spores.
Anthrax spores.
Cholera.
Typhoid.
Staphylococcus and
streptococcus pyog.
Anthrax spores.
/Nearly all patho-
\ genie germs.
Anthrax spores
All other patho-
genic germs
1 minute.
70 hours.
2 hours.
2 hours.
10 days.
53 days.
8 days.
6 days.
5 days.
Iday.
6 hours.
6 hours.
} &-11 seconds.
24 hours,
f Less than
1 30 minutes.
15 minutes.
| 1 minute
In any case of infectious disease special attention should
be given to disinfecting the excretions and secretions which
are known to be most likely to contain the disease germs,
280 A MANUAL OF HYGIENE AND SANITATION.
viz., the desquamating epithelium in measles and scarlet
fever, and likewise the renal secretion in the latter; the
dejecta in typhoid fever; the sputum and possibly the
dejecta in tuberculosis; secretions from the throat in
diphtheria, etc.
During the course of the illness there should be no
more communication than is absolutely necessary between
the occupants of the sick-room and those in the rest of the
house, and a sheet should be hung at the door and kept
moist with some disinfecting solution, as this will largely
prevent the escape of infected dust particles through the
doorway. All articles going from the room, whether
dishes, clothing, or food, should be submerged in a disin-
fectant or covered with a cloth wet with it, and should be
burned, boiled, or otherwise disinfected as soon as possible
thereafter. Excreta should be disinfected as soon as dis-
charged from the body, but should not be emptied into a
water-closet, sewer, or cesspool till the disinfectant has
had ample time to do its work. Ventilation should be as
perfect as possible; sunlight should be admitted whenever
it will not injure or annoy the patient, and, above all, clean-
liness in every respect should be insisted upon as being
most essential.
It is taken for granted that, if possible, before the occu-
pancy of the room by the sick, all upholstered furniture,
heavy drapery, and everything not absolutely necessary
were removed from the room. Even the carpet should be
taken up and rugs used temporarily in its place. If this
is done, the work of disinfecting the room after it is no
longer needed by the patient will be greatly facilitated.
Where the use of formaldehyde is not available, the final
disinfection should be carried out as follows : All bed-
clothing, etc., should be either submerged in some disin-
DISINFECTION AND QUARANTINE. 281
fectant solution or in boiling water, or else covered with a
sheet wet with a disinfectant, and boiled as soon as possible
thereafter. No clothing should be sent away from the
house to be laundered. Bedquilts, blankets, mattresses,
etc. should be subjected to steam sterilization if possible;
if not, the blankets and quilts should be carefully sterilized
by boiling, and the mattresses would better be burned. The
carpet or rugs should be carefully taken up, carried to an
open space, well beaten, and then hung in the open air for
a time, provided they cannot be sent at once to some
place where steam sterilization is available. All furni-
ture and the woodwork of the room should be washed
with corrosive sublimate solution (1 to 500 or 1000), tak-
ing care to get the fluid into all crevices. The floor
may be scrubbed with lye, and then mopped and flooded
with a corrosive sublimate solution. The walls should
also be wiped with cloths wrung out of this solution and any
paper upon them removed before fumigaton, unless it be
new and free from cracks. Or the walls may be rubbed
down with the crumb of bread and the latter burned, as the
bread contains much gluten, to which the dust and bacteria
adhere. Fumigation will scarcely be necessary, and is
usually of somewhat doubtful efficiency. If it is employed,
all openings from the room, cracks, crevices, etc., should be
closed on the outside, and sufficient gas (chlorine or sul-
phurous acid) liberated by suitable means. The vessels
containing the gas-generating substances should be placed
in larger vessels containing water to avoid the danger of
fire, and vapor of water should be liberated in some way
simultaneously with the gas, say by placing hot bricks or
the like in the water, as neither chlorine nor sulphurous
acid has much disinfecting value except in the presence of
moisture. The room should then remain closed for twenty-
282 A MANUAL OF HYGIENE AND SANITATION.
four hours and, lastly, should be well ventilated for a
day or two before being furnished and occupied again.
Should it be possible to use formaldehyde, the disin-
fection is much simplified, for comparatively few articles
need be removed from the room, while the remainder will
probably be thoroughly sterilized by the proper use of a
sufficient quantity of the gas, say that liberated from one
pint of a 40 per cent, solution for each 1000 cubic feet of
space.
Quarantine.
Quarantine may be described as the methods and meas-
ures imposed by a government — local, State, or national —
to prevent the introduction of infectious disease into the
country or from one locality to another. Although the
term in itself is misleading, being derived from the Italian
" quarante," and signifying the period of detention of the
first Venetian quarantines, it is now generally taken to
indicate the entire routine of inspection, disinfection, and
detention, without regard to the length of time involved.
While all civilized nations have from the earliest times
recognized the importance of separating those afflicted with
epidemic disease from the well, the development of the
idea and practice of quarantine has necessarily been con-
sequent upon the growth of commerce; and while there
had practically always been isolation for leprosy, the first
quarantine enactments, in our meaning of the term, were
put in force in Venice about the beginning of the fifteenth
century as a barrier to both the black and the Egyptian
plague. Then it was realized that epidemic diseases were
transmitted by those attacked, a bureau of health and a laz-
aretto were established, the effects of those who died of the
plague were destroyed, and the period of detention of incom-
ing vessels, passengers, and cargoes was fixed at forty days.
DISINFECTION AND QUARANTINE. 283
As time went on and the plague spread over the whole
of Europe, the number of lazarettos was largely increased,
especially in the eighteenth century. Of these, the one
at Marseilles became the most noted, not only because it
was located at one of the most important ports of the
Mediterranean, but because of its excellent care and man-
agement. Thanks to the increased efficacy of quarantine
and other sanitary regulations, as the knowledge concern-
ing them developed, the plague rapidly subsided soon after
the beginning of the present century, and interest in it
was supplanted by that in relation to the frequent epi-
demics of cholera and yellow fever that began to alarm
the civilized world, and it is to prevent the ingress of
these latter diseases, together with small-pox and. typhus
fever, that the present quarantine regulations are in the
main devised.
With the knowledge already gained regarding the
nature and causes of infectious diseases, their periods of
incubation, etc., it is at once evident that it will be neither
necessary nor wise to fix upon a prolonged and arbitrary
time during which vessels or passengers must be detained
in quarantine. All that is needed is that the proper inspect-
ing officers shall be satisfied that there is no danger of
contagion entering the country, and where any detention
is necessary it is only for so long as will suffice for the
disinfection of the vessel, cargo, and passengers' effects,
and to cover the period of incubation of the suspected
disease.
The present quarantine laws of the United States, and
the latest regulations of the Treasury Department based
upon them, are especially designed to afford the greatest
possible protection to the country against the importation
of disease with the least possible detention of incoming
284 A MANUAL OF HYGIENE AND SANITATION.
vessels and passengers. An important innovation that
facilitates both these ends has been the establishment of
quarantine in foreign lands, as it were, viz., the inspection
and, if necessary, disinfection by officers of this govern-
ment of all vessels, passengers, and cargoes leaving a
foreign port for any port of the United States. This
undoubtedly greatly diminishes the danger of the intro-
duction of any contagious disease; but, in addition, there
is that section of the law that provides that the President
may, whenever the condition of affairs shall seem to war-
rant it, " prohibit, in whole or in part, the introduction of
persons and property from such countries or places as he
shall designate and for such period of time as he shall
deem necessary."
Accordingly, every vessel clearing from a foreign port
for this country must obtain from the United States con-
sular officer of the port, or from the medical officer ap-
pointed for the purpose, a bill of health, " setting forth
the sanitary history and condition of said vessel, and that
it has in all respects complied with the rules and regu-
lations in such cases prescribed for securing the best
sanitary condition of the said vessel, its cargo, passen-
gers, and crew." Before signing the bill of health the
consular or medical officer must be satisfied that the
conditions certified to therein are true, and must per-
sonally inspect " all vessels from ports at which cholera
prevails, or at which yellow fever, smallpox, or typhus
fever prevails in epidemic form," and " all vessels carry-
ing steerage passengers." Moreover, the vessel must be
clean in all parts before taking on either passengers or
crew, and all parts liable to infection must be disinfected,
if any infectious disease has occurred on the last voyage.
The bedding provided for steerage passengers must also
DISINFECTION AND QUARANTINE. 285
be destroyed or else disinfected before being used on
another voyage.
The regulations also indicate what kinds of cargo, com-
ing from or through infected districts, may or may not be
shipped, and what kinds must invariably be disinfected
under any circumstances.
As to the passengers, while they are divided into two
classes, cabin and steerage, no person suffering from
cholera, smallpox, yellow or typhoid fever, scarlet fever,
measles, or diphtheria is allowed to ship; nor should pas-
sengers ship from an infected port. Steerage passengers
and crew who have been exposed to smallpox must be
vaccinated before shipping unless they can show proof of
immunity by former attack or satisfactory vaccination. If
the steerage passengers and crew have been exposed to
typhus-fever infection they may not embark until fourteen
days after such exposure and the disinfection of their bag-
gage, while steerage passengers from cholera-infected dis-
tricts must be detained in suitable quarters for five days,
' ' the said period to begin only after the bathing of the
passengers, disinfection of all their baggage and apparel,
removal of all food brought with them, and isolation from
others not so treated." The same rules as to detention
and disinfection are to be applied to those coming from
places where the plague, yellow fever, or smallpox is prev-
alent in an epidemic form, and if one of these diseases or
cholera breaks out in the detention barracks there must be
a repetition of the five days' isolation, disinfection, etc.,
dating from the removal of the last case. Cabin passengers
from cholera or other infected ports or districts should pro-
duce satisfactory evidence as to their place of abode for the
five days immediately preceding embarkation, and if there
is any reason for the belief that any one of these or his
286 A MANUAL OF HYGIENE AND SANITATION.
baggage has been infected, such passenger is to be detained
as long as the inspecting officer may deem wise, and his bag-
gage is to be disinfected.
Every passenger must also have an inspection-card,
stamped by the consular or medical officer, giving name
of passenger, and of ship, port, and date of departure, etc. :
and all baggage of passengers must have a label bearing
the seal or stamp of the United States consular or medical
officer, the name of port and of the vessel carrying the
baggage, and the statement and date of inspection or
disinfection.
It is evident that if these regulations at foreign ports,
together with those required at sea — viz., rigorous clean-
liness and free ventilation of the vessel, daily inspection
by the ship's physician, isolation and disinfection of the
sick, etc. — be properly observed, there can be but little
chance of the germs of quarantinable disease gaining
entrance to our country, and, since the duration of the
voyage will in most cases exceed the period of incubation
of most of the contagious diseases, if none of these mani-
fest themselves on shipboard at sea there will be no need
for any detention at the port of entry beyond that which
the inspecting officer stationed there requires for the per-
formance of his duties, viz., to inspect the vessel, bill of
health, crew, and passengers, and their lists and manifests,
ship physician's clinical record of all cases treated, and,
when necessary, the ship's log.
This inspection service is to be maintained at every port
throughout the year, and is in force not only with respect
to all vessels from foreign ports, but regarding any vessel
with sickness on board, vessels from domestic ports where
cholera or yellow fever prevails, or where smallpox or
typhus fever prevails in epidemic form, vessels from for-
DISINFECTION AND QUARANTINE. 287
eign ports carrying passengers having entered a port of
the United States without complete discharge of passen-
gers or cargo, and vessels having been treated at national
quarantine stations that are located a considerable distance
from the port of entry of said vessels. Moreover, the
duties of the inspecting officer above stated are only the
required minimum standard, and such other regulations
may be added by legal State or local authorities as may,
for special reasons, be necessary.
If the inspecting or health officer is satisfied that the
vessel is not infected, and all the foregoing requirements
have been complied with, he gives his certificate, to be
delivered to the collector of customs of the port, and no
vessel is permitted to land any of its passengers or cargo
unless it have this certificate, together with the bill of
health, etc., from the port of departure, as evidence that
the regulations have been properly observed. On the
other hand, if vessels arrive under the following condi-
tions they are to be remanded by the authority of the
Secretary of the Treasury to the nearest national or other
quarantine station, where proper accommodations and ap-
pliances are provided for the necessary disinfection and
treatment of the vessel, passengers, and cargo; and only
after treatment and after obtaining a certificate from the
proper officer that the vessel, cargo, and passengers are
each and all free from infectious disease, or from danger
of conveying the same, can a vessel be admitted to entry
to the ports named in the certificate.
The conditions under which arriving vessels are to be
placed in quarantine are these : "A. With quarantine dis-
ease on board, the quarantinable disease for the purposes
of these regulations being cholera (cholerine), yellow fever,
smallpox, typhus fever, and leprosy. B. Having had
288 A MANUAL OF HYGIENE AND SANITATION,
such on board during the voyage or within thirty days
next preceding arrival; or, if arriving in the quarantine
season, having had yellow fever on board after March 1st
of the current year, unless satisfactorily disinfected there-
after. C. From ports infected with cholera or where typhus
fever prevails in epidemic form, coming directly or via
another foreign port, or via United States ports, unless
they have complied with the United States quarantine
regulations for foreign ports; also vessels from non-infected
ports, but bringing persons or cargo from places infected
with cholera, yellow fever, or where typhus fever prevails
in epidemic form, except as subsequently noted. D. From
ports where yellow fever prevails, unless disinfected in
accordance with these regulations, and not less than five
days have elapsed since such disinfection.
" The following exceptions may be made to Rules C.
and D. with regard to vessels quarantined against on
account of yellow fever : (1) Vessels arriving from
November 1st to May 1st may be admitted to entry.
(2) Vessels bound for ports in the United States north of
the southern boundary of Maryland, with good sanitary
condition and history, having had no sickness on board at
ports of departure, en route or on arrival, provided they
have been five days from last infected or suspected port,
may be allowed entry at port of destination. But if said
vessels carry passengers destined for places south of this
latitude the baggage of said passengers shall be disin-
fected, and such baggage shall be labelled. (3) Vessels
engaged in the fruit trade from ports declared safe for this
purpose by the Supervising Surgeon-General of the Marine
Hospital Service may be admitted to entry without deten-
tion, provided they carry no passengers and have carried
no passengers from one port to another, and have no
DISINFECTION AND QUARANTINE. 289
household effects or personal baggage in cargo, and have
complied with the rules and regulations made by the Sec-
retary of the Treasury with regard to vessels engaged in
said trade."1
Moreover, all passengers other than those occupying
first or second cabin, and all persons arriving on vessels
that have had smallpox on board, must be vaccinated or
detained in quarantine not less than fourteen days, unless
they can show satisfactory evidence of recent vaccination
or of having had smallpox; and all effects and compart-
ments liable to convey infection must be disinfected.
" No case of leprosy will be landed, and vessels arriving
at quarantine with leprosy on board shall not be granted
pratique until the leper with his or her baggage has been
removed from the vessel to the quarantine station. If
the leper is an alien passenger and from a foreign port,
action will be taken as provided by the immigration laws
and regulations of the United States. If the leper is an
alien and a member of the crew, and the vessel is from a
foreign port, said leper shall be detained at quarantine at
the vessel's expense, until taken aboard by the same vessel
when outward bound. "2
There are ten national quarantine stations and a number
of others under State or municipal control; those which
have steam disinfection chambers and other efficient equip-
ments are located at Portland, Me. ; Boston, New York,
Sandy Hook, Delaware Breakwater, Reedy Island in the
Delaware River, Cape Charles, Baltimore; Wilmington,
N.C. ; Savannah, Blackbeard Island, Ga. ; Charleston, Dry
Tortugas, Key West, Mullet Keys, Pensacola, Mobile,
Chandeleur Islands, New Orleans, Galveston, San Diego,
i Quarantine Laws and Regulations of the United States. 2 Ibid,
19
290 A MANUAL OF HYGIENE AND SANITATION.
San Francisco, and Port Townsend; the ten national ones
being included in the list.
The essential requisites for a properly equipped quaran-
tine station, after the selection of a proper location — which
should be convenient, but not in the line of future city
growth — are the following:1 1. A boarding station, includ-
ing boat-house and boatmen's quarters. 2. A boarding-
boat, preferably a steamer. 3. An anchorage for the de-
tention of infected vessels. It should be safely out of the
track of commerce, convenient but not too close to the
main quarantine establishment, sheltered, and with good
holding ground for anchors. 4. A fumigation steamer
with appliances for generating and forcing sulphurous-
acid (or formaldehyde} gas into vessels, and with tanks
and pumps for disinfecting solutions. 5. A wharf, in
water at least twenty feet deep, and upon which are con-
structed a warehouse, tanks for disinfecting solutions, and
a disinfecting house containing steam disinfecting cham-
bers. 6. A lazaretto or hospital for the treatment of
contagious diseases. 7. A hospital for non-contagious dis-
eases. 8. Barracks or quarters for the detention in groups
of those who may have been exposed to contagion or
infection. 9. Quarters for medical officers. 10. A cre-
mation furnace.
When a vessel is remanded to quarantine by the inspect-
ing officer at a port of entry, its treatment and that of its
cargo and passengers will depend largely upon the disease
with which it is infected, being more severe if the latter
is cholera or yellow fever. In case of infection by either
of these diseases, the vessel is at once sent to the anchorage,
and must remain there until the passengers have been dis-
i RohS's Hygiene.
DISINFECTION AND QUARANTINE. 291
charged and the vessel purified, and in any case there must
be no direct communication allowed between quarantine,
or a vessel in quarantine, and any person or place outside.
Moreover, if cholera has occurred on board, all passen-
gers and all of the crew, except such as are necessary to
care for her, must be at once removed, the sick to be sent
to the lazaretto or hospital, others specially suspected must
be carefully isolated, and the remainder separated into
small groups, between which there must be no communi-
cation. Those who are especially liable to convey infec-
tion must be bathed and furnished with sterile clothing
before entering the barracks, and no articles capable of
carrying infective matter, especially food, should be taken
into the barracks. If the disease has occurred in the
steerage, all the steerage passengers must be bathed and
their clothing disinfected; and in any case all steerage
baggage and effects, and any other baggage, etc. , that has
been exposed to the infection, all articles of the cargo
likely to be infected, and all living apartments, furniture,
and such other portions of the vessel as may possibly
retain or convey infection must be disinfected. The water-
supply must be changed at once, the tanks thoroughly dis-
infected by steam or permanganate of potash solution, and
refilled with water from a pure source or with water
recently boiled. The water-ballast of a cholera-infected
vessel, or of one from a cholera-infected port, should
never be discharged in fresh or brackish water without
previous disinfection, and the ballast-tanks should be re-
filled with sea- water or else be disinfected before refilling.
Nothing is to be thrown overboard from a cholera-infected
vessel in quarantine, but everything that is to be destroyed,
even deck-sweepings, should be burned in the furnace.
The disinfection of the holds of vessels is to be by
292 A MANUAL OF HYGIENE AND SANITATION.
mechanical cleansing, by an acid bichloride of mercury
solution (1 to 800) applied under pressure, and by sul-
phurous-acid gas (10 per cent, volume strength) for from
twenty-four to forty-eight hours. All ballast must be
discharged or disinfected before the disinfection of the
hold, and all solid . ballast must be disinfected before
being discharged into fresh water. The steerage and fore-
castle are to be disinfected by live steam, if possible, for
at least half an hour, and, if not, by sulphur dioxide and
bichloride solution, as was the hold. Baggage, bedding,
carpets, etc., are to be removed with caution and to be
disinfected by steam or by boiling, and, finally, all wood-
work of the vessel is to be thoroughly cleansed mechani-
cally and then washed with an acid bichloride of mercury
solution (1 to 1000).
Under date of August 5, 1897, the Secretary of the
Treasury issued a circular to State and local quarantine
authorities t( amending Article 5 of the quarantine regu-
lations to be observed at ports and on the frontiers of the
United States, by adding two paragraphs, 8 and 9.
"Disinfection of steerage, forecastle, and cabin of vessels by
formaldehyde gas. After the removal of the bedding, car-
pets, and furnishings, all apertures being tightly closed,
the steerage, forecastle, and cabin of a vessel may be dis-
infected by formaldehyde gas in a percentage of not less
than 2 per cent, per volume strength, the time of exposure
to be not less than twelve hours. The gas may be gen-
erated by the following method :
"From an aqueous solution, containing 40 per cent, of
the gas, known under the names of formaldehyde, formol,
or formolose. The gas is best evolved from these solutions
by the addition of from 10 to 30 per cent, of a neutral
salt, preferably calcium chloride or sodium nitrate, and
DISINFECTION AND QUARANTINE. 293
heating the mixture in a special boiler. One litre of a 40
per cent, solution of formaldehyde gas will evolve about
1425 litres (50.1 cubic feet) of the gas at 20° C. (68° F.),
and will be sufficient for 17 cubic metres (2505.5 cubic
feet) of space.
" After the disinfection of apartments by formaldehyde
gas, the latter should be neutralized by ammonia gas,
evolved from water of ammonia by heat, or by evapora-
tion from water of ammonia sprinkled upon the floor.
The quantity of water of ammonia required for neutrali-
zation, after the above-named method, is as follows : 1 J
litres (1.26 quarts) of water of ammonia for each litre
(1.01 quarts) of formaldehyde solution.
"Disinfection of clothing, bedding, upholstered furniture,
articles of leather, etc. , by formaldehyde gas. These may
be disinfected by formaldehyde gas in the ordinary steam
disinfecting chamber, the latter to be provided with a
vacuum apparatus and special apparatus for generating
and applying the gas. The gas should be applied in a
dry state in not less than 20 per cent, per volume strength,
the time of exposure to be not less than one hour.
"The application of the disinfectant can, of course, be
modified to suit the circumstances of the case, but the fore-
going will be useful as indicating the principles which
must be followed."
As to the passengers and others who have been isolated
in groups, they are to be inspected twice daily by the physi-
cian and remain under his constant surveillance, and can
have no communication with any one in a different group
or outside of quarantine, except through the quarantine
officer. The water- and food-supply is to be strictly
guarded, and is issued to each group separately. The
latter is to be simple in character and abundant in quan-
294 ^ MANUAL OF HYGIENE AND SANITATION.
tity, but no fruit is to be permitted. Strict cleanliness is
to be enjoined, disinfection wherever necessary, and, in
case cholera appears in any group, the sick will be imme-
diately removed to the hospital, and the rest of the group
bathed and their effects disinfected, and all then removed
to other quarters, if possible. None are to leave quaran-
tine until five days after the last exposure to infection and
the final disinfection of such effects as were taken to bar-
racks; and no convalescent may leave quarantine until a
bacteriological examination shows him to be free from
infection.
As has been stated, the treatment of vessels infected by
other diseases is not necessarily so severe as the above, but
in each case every effort is made to allow no loophole for
the entrance of infection into the country; and in the case
of yellow fever there is to be the same isolation of all not
required to care for the vessel and a detention of at least
five days after disinfection has been thoroughly performed
and completed. The detention for typhus fever is to be
twenty days, and for smallpox fourteen days, the detention
dating from the last exposure to either disease.
No vessel may leave quarantine until she has a certifi-
cate from the health (quarantine) officer that she has in all
respects complied with the quarantine regulations, and
that, in his opinion, she will not convey quarantinable
disease. She is then said to be granted free pratique.
The law farther provides that " When practicable, alien
immigrants arriving at Canadian and Mexican ports, des-
tined for the United States, shall be inspected at the port
of arrival by the United States consular or medical officer,
and be subjected to the same sanitary restrictions as are
called for by the rules and regulations governing United
States ports; that inspection cards will be issued by the
DISINFECTION AND QUARANTINE. 295
United States officer at the port of arrival to all such
immigrants, and labels affixed to their baggage, as in the
case of foreign ports; and where such immigrants are not
inspected at the port of arrival they shall enter the United
States only at certain designated points on the frontier,
and then only after such inspection, detention, disinfec-
tion, vaccination, etc. as may be necessary or required by
the officers there stationed.
There is also provision for the inspection of State or
local quarantines from time to time by the Supervising
Surgeon-General of the Marine-Hospital Service, or by
an officer of that service detailed by him; and for the
observance at all quarantines of such additional rules and
regulations as may from time to time be promulgated by
him.
Inland Quarantine. Under this heading may be con-
sidered the means that may be employed to prevent an
epidemic extending from one locality or district to another,
although the principle and aims are practically the same
as those of maritime quarantines, viz., to define certain
boundaries beyond which no person or thing capable of
carrying infection may pass, and to establish certain
points of ingress or egress on these boundaries where
there may be the necessary detention, inspection, disinfec-
tion, etc.
The sanitary cordon " consists of a line of guards, mili-
tary or civil, thrown around a district or locality, either
to protect the same from the surrounding country when
infected, or to protect the surrounding country from the
infected district or locality." "It is not intended to
bottle up all the people who are caught within an infected
district, but, on the contrary, is intended as a means of
exit to those who will not carry with them contagious dis-
296 A MANUAL OF HYGIENE AND SANITATION.
eases to the people beyond.m It may be single or double;
in the latter case the inner line closely encircles the well-
defined infected locality, and the outer line the whole sus-
pected territory. This latter may be removed as soon as
it is evident that the space between it and the inner line is
not infected. To be efficient the cordon must be so guarded
that, even though it be many miles in length, no unauthor-
ized person may pass through it, while at certain places
upon it camps of probation or detention must be estab-
lished, where all persons coming from the infected locality
may be kept under observation for a time equal to the
period of incubation of the disease in question. These
camps of probation or detention are to be distinguished
from the camps of refuge, which were first suggested by
Surgeon-General Woodward in 1878, and which are
" simple residence-camps established to receive the popu-
lation of an infected community when it has been deter-
mined to depopulate the infected district.77
At these camps of probation provision must be made
for inspecting every person and disinfecting all baggage
before entering camp, for isolating the occupants and
housing and feeding them in the most comfortable and
sanitary manner during the detention, for inspections
twice or thrice daily, for the isolation and care of the sick
in hospitals at a safe distance from camp, and for the issu-
ance of a certificate granting " f ree pratique" when the
period of detention is over.
A notable instance of the sanitary cordon was that about
the city of Brownsville, Texas, and along the Rio Grande,
in 1882; and of a probation camp, that at Camp Perry,
Florida, in 1888.
* RohS's Hygiene : Quarantine.
DISINFECTION AND QUARANTINE. 297
In addition to these measures it may be necessary or
advisable to establish a railroad quarantine, as follows: At
certain convenient points, which will be the only points
of egress by rail from the infected district, an inspec-
tion service and disinfecting station are to be maintained
throughout the epidemic. Here all the baggage and
freight is to be properly disinfected and all passengers
are to be examined by the official inspectors; if the latter
are from the infected locality, or have not a certificate from
some recognized health officer as to where they have been
for the previous days corresponding to the incubative
period of the disease, they are to be at once remanded to
the nearest camp of probation, there to undergo the neces-
sary detention. Moreover, it may seem advisable to pre-
vent any passenger cars going beyond the infected district,
and to disinfect all freight and baggage cars that do so.1
1 In the foregoing chapter the author has attempted to present briefly the prin-
ciples and the regulations of quarantine as practised in the United States at the
present time ; but the reader is referred for further details to the extremely inter-
esting and valuable chapter on the subject in Rohe's " Text-Book of Hygiene,"
by Dr. Wyman, the present Supervising Surgeon-General of the Marine-Hospital
Service.
•CHAPTEK XI.
THE REMOVAL AND DISPOSAL OF SEWAGE.
THE waste from dwellings is of three kinds : house-
sweepings and the ashes from fires; the waste from kitch-
ens, scraps of food, etc., commonly known as garbage;
and sewage, the most important, consisting as it does of
the solid and liquid excreta of the body, together with
waste water from wash-tubs, bath-tubs, kitchens, laun-
dries, etc.
Ashes alone have little effect upon the health, except
that they absorb moisture readily, and if allowed to accu-
mulate in a cellar may do much to keep it damp and
mouldy. For the same reason, if they be mixed with
refuse vegetable matters, putrefaction is favored and nox-
ious emanations given off. The dust from ash heaps may
also be carried into the house and largely increase the solid
impurities of the air therein. Consequently, ashes should
be frequently and regularly removed from the premises.
Kitchen garbage readily decays, and if allowed to re-
main in the vicinity of the house may pollute both the air
and soil about it; but inasmuch as it has some value as a
food for animals, there is usually no difficulty in having
it removed by scavengers without expense or delay. Care
must be had, however, that this is done properly, and that
all receptacles are kept in as cleanly a condition as possi-
ble. Most large cities now find it safer to collect and
cremate the garbage at the expense of the municipality,
rather than to allow private individuals to keep large
THE REMOVAL AND DISPOSAL OF SEWAGE. 299
numbers of animals within or near the city limits for its
consumption. Even though the former plan be the more
costly, experience shows that this garbage may be com-
pletely consumed in properly arranged crematories at con-
venient localities without inconvenience or annoyance to
the residents of the vicinity, thus saving the expense and
time necessary for conveying the garbage beyond the
municipal limits.
The kind of waste to which we give the name of sewage
is, however, of most importance to sanitarians, since it is
always a possible factor in the production of disease, and
since it presents the most difficulties in respect to its re-
moval from dwellings and the ultimate disposal of it.
In addition to the substances already named, and which
usually come from dwelling-houses, sewage may contain
the liquid excreta from stables, the refuse from factories
of all kinds, the drainage from polluted soils, and the
excess of rain-water not taken up by evaporation or
retained in the soil. Its composition must, therefore, be
always complex and variable ; but there will practically
always be present in it chloride of sodium, ammonia, car-
bon monoxide and dioxide, hydrogen and ammonium sul-
phide, fetid and decomposing organic matter, and myriads
of bacteria. Fresh sewage will not be as offensive to the
senses as that in which putrefaction has commenced, nor
will the gases arising from it be as dangerous to health.
Frankland has shown that " solid or liquid matter is
not likely to be scattered into the air from the sewage
itself by any agitation it is likely to undergo until gas
begins to be generated in it;" and it is really doubtful
whether the air of a properly constructed and well-venti-
lated sewer can be shown to contain a harmful excess of
injurious gases and organisms. However, it is essential
300 A MANUAL OF HYGIENE AND SANITATION.
that sewage should always be removed from the premises
of a dwelling as soon as possible after its production and
before decomposition begins.
When the above-mentioned constituents of sewage are
to be disposed of collectively, the water-carriage system is
usually the best. Although the pneumatic system (wherein
air-tight pipes extend from the dwellings, etc., to reser-
voirs from which the air is periodically exhausted and the
sewage thus drawn into them), would seem to be advan-
tageous where the topographical conditions do not permit
of natural drainage, it is always subject to the danger of
breaks occurring and destroying the action, and seems to
have been practically successful in but very few instances.
On the other hand, where house refuse only is to be
considered and where the waste water can be kept from
the other parts of the sewage, or where the water-supply,
the physical conditions, or the cost of constructing the
necessary sewers prevent the use of the water-carriage
method, recourse must be had to the pail or earth-closet
system. The use of primitive privy-vaults or cesspools is
most insanitary and dangerous, and should be condemned
in almost every instance. Where the necessity for one of
these seems imperative, it should always be made abso-
lutely water-tight, so that none of the contents may escape
to pollute the surrounding soil and soil-air and to contam-
inate the ground-water in the neighborhood. Moreover,
the pits should be properly ventilated and should be
cleaned out regularly and often, which may be done satis-
factorily and without offence by some form of odorless
excavating apparatus, such as is now commonly used.
No drains or sewers should empty directly into a cess-
pool, but these should always be trapped and have com-
munication with the open air, and no cesspool should
THE REMOVAL AND DISPOSAL OF SEWAGE. 3Q1
empty into a common or public sewer. It should be
noted that the contents of such a vault, or of a simple pit in
the earth, undergo putrefaction rather than natural decom-
position, because of the lack of sufficient oxygen supply
and of the adjunct action of the nitrifying bacteria which
are found only in the uppermost layers of the soil. It is
also probable that many disease germs will survive and
multiply better in the contents of such a vault than in
sewage or refuse treated by the methods to be hereafter
described.
In the pail system the more solid waste matters, and
especially human excreta, are collected in a suitable pail
or tub, which, holding only a limited amount, must of
necessity be removed and emptied regularly and often. If
the outbuildings used for this purpose be kept clean and
properly ventilated, such a system will be both economical
and healthful.
Advantage may here be taken of the great deodorizing,
nitrifying, and oxidizing power of fine dry earth, and
various forms of earth-closets have been devised to be used
in conjunction with the pail-system. If a quantity of dry
earth, in bulk about twice that of the dejecta, is thrown
upon the latter after using the closet, they will be rendered
perfectly inodorous and inoffensive. For this purpose
loam and clay are best, though sifted ashes may be used
with almost as good results, but sand or gravel will not
be so efficient as the loam or ashes. Moreover, owing
probably to the action of the nitrifying bacteria in the
earth, all trace of the peculiar nature of the organic com-
pound is quickly destroyed, and the mixture soon be-
comes practically humus and an excellent fertilizer.
The pail or earth-closet must, of course, be separate and
apart from the dwelling, as it is impossible to have the
302 A MANUAL OF HYGIENE AND SANITATION.
same means of keeping the gaseous emanations and effluvia
out of the house as with the water-carriage system; and
it also goes without saying, that the liquid house-slops,
wash-water, etc., must be kept separate from the fecal
waste, which should be kept as dry as possible to lessen
putrefaction and to increase its possible value as a fertil-
izer. Nor should this liquid waste be allowed to soak
into and pollute the soil about the house. It should be
collected in a water-tight reservoir, whence it can be
removed at frequent intervals, or, better yet, carried by
suitable drains to a kitchen garden or other land at a
proper distance from the house, and be there disposed of
by irrigation or sub-irrigation.
As one can readily see, this pail system is especially
well adapted to isolated houses and small communities,
where each householder can take care that the necessary
details are properly attended to, and where, as is likely,
there is not a general water-supply, or where the expense of
constructing the necessary sewers would be too great. But
even in cities as large as Manchester, England, " where
four-fifths of the people are obliged to have earth-closets/7
the system is said to have proved entirely advantageous
and practicable.
Where there is a common and general supply of water
throughout the house or to a number of houses there
must be some provision for carrying off the waste water,
and as this latter will have probably become polluted in
its use, it will be advantageous to utilize it to remove the
other sewage. In fact, where the conditions are favorable
the water-carriage system will usually be found the best
of all, because it is more nearly automatic, and depends
least on human interference and efficiency.
The necessary apparatus comprises, on the one hand,
THE REMOVAL AND DISPOSAL OF SEWAGE. 303
that which belongs to the building and its premises, viz.,
the house fixtures, pipes, and drains; and, on the other
hand, the common or public sewers which receive the sew-
age from the above and convey it to its place of ultimate
disposal.
Sewage-plumbing and House-drainage.
The essence of any good system for the removal of sew-
age from a dwelling or building is simplicity. Therefore,
inasmuch as it has already been stated that sewage should
always be removed from the premises as soon as possible
after its production and before fermentation or putrefac-
tion begin in it, it is evident that in such a system we
should have for our object and should provide for : " 1.
The speediest possible removal from the house to the
public sewer of excretal and other refuse by means of
water. 2. The prevention of the deposit of foul matter
in any part of the drainage system and of percolation
into the soil of polluting liquids. 3. The establishment of
a current of air through every part of the soil-drains and
pipes, in order to disperse any foul gases that may form
and to allow them to escape with safety into the open air.
4. The prevention of any entry of air from soil-pipes,
drains, and waste-pipes into the house. 5. The exclusion
of the air of the common sewer from the house-drains and
the house; the last being, perhaps, the most important, as
the air of the public sewer may at any time contain the
active germs of specific disease/71
This is to be done in the manner to be described. The
soil-pipe is that which receives the sewage from water-
closets and, usually, from the waste-pipes of other fixtures,
i L. C. Parkes : Hygiene and Public Health, 2d edition, p. 139,
304 A MANUAL OF HYGIENE AND SANITATION.
such as the bath-tubs, washstands, sinks, etc., and which
connects them with the house-drain; the latter is the con-
duit connecting the soil-pipe with the sewer. Waste-pipes
convey the contents of washstands and other fixtures to
the soil-pipes or to a branch of the house-drain.
The soil-pipe is usually located almost entirely within
the house, although, were it not for the danger of its con-
tents freezing, it would be better to have it fastened to the
wall outside. It is usually made of cast or wrought iron,
should be at least four inches in diameter, should convey
the sewage as directly as possible from the fixtures to the
house-drain, and must extend unobstructed from the latter
to several feet above the roof, ending where winds and
currents from high walls and chimneys will not interfere
with its free ventilation. Every branch of the soil-pipe
more than eight feet in length, or to which two or more
water-closets are connected, should also be extended above
the roof, or else be extended and connected to the main
soil-pipe above the highest fixture connected therewith, as
there must be no closed ends wherein foul or stagnant air
may collect. All joints must be absolutely air-tight, and
the pipe must be so secured that any vibration or settling
of the building will not be likely to destroy its continuity.
In new buildings, especially, all soil-pipes should be ex-
posed or else covered in with panels easily removable at
any time to permit of inspection or repairs. Any hidden
pipes or those difficult of access should be of extra heavy
materials, and extra care should be given to the joints and
supports. The soil-pipe and house-drain should both be
as smooth as possible interiorly, and in the construction
they must be carefully inspected to prevent any of the
material used in daulking or cementing the joints from
projecting within to prevent the free flow of sewage.
THE REMOVAL AND DISPOSAL OF SEWAGE. 305
Outside of the house the house-drain may be of iron or
of glazed and impervious earthenware, but no earthen pipe
FIG. 41.
WASH BASIN
WASH BASIN
V
BATH-TUB/
Diagram illustrating the sewage-plumbing of a house. The traps of the rain-
leaders at their junctions with the house-drain, and the name of the latter, have
been accidentally omitted.
should be permitted within five feet of a foundation wall,
and where any part of the house-drain is within the build-
20
306
MANUAL OF HYGIENE AND SANITATION.
ing it should be of iron and securely fastened to the
foundation- wall above the cellar floor. The connection
between it and any soil-pipe should be by means of a
rounded elbow and not by an abrupt right angle. The
house-drain should not be less than four nor more than
ten inches in diameter, should be laid on a firm founda-
tion, should have air-tight joints, and should have a slope
toward the sewer of at least one-half inch to the foot.
A house-drain should not empty into a cesspool, unless it
is absolutely necessary, and in such case the cesspool must
be well ventilated and also separated from the drain by
a trap. Nor should any cesspool empty into a sewer.
PIG. 42.
Method of connecting soil-pipe with house-drain.
If a house-drain empty into a sewer of the ' ' combined ' '
system there must be a trap just before its junction with
the sewer to prevent the passage of sewer-air back into
the house, and there must also be an opening for fresh air
between this trap and the foot of the soil-pipe, so that
there may be a constant current of air through the drain
THE REMOVAL AND DISPOSAL OF SEWAGE. 307
and soil-pipe to the exit above the roof, and the air in the
soil-pipe thus kept from becoming foul and stagnant. But
if the house-drain empties into a sewer of the " separate "
system, there need be no trap between the drain and
sewer, for the reasons to be hereafter stated; however, the
fresh-air inlet between sewer and soil-pipe is always
advisable, as it tends to further assist ventilation.
Where rain-water conductors empty into house-drains
or sewers, they should be separated from the latter by
traps having a seal of not less than five inches, to prevent
sewer-air passing up through them to the vicinity of win-
dows, etc.
In the house all water-closets and other fixtures should
be as near the soil-pipe as possible, that there may be no
long stretches of foul waste pipe underneath the floors,
and all connections with the soil-pipe should be made at
an acute angle, that the discharge into the latter may not
interfere with its free ventilation. Each fixture must be
separately trapped and the trap must be located as near
its fixture as possible. There must be no connection be-
tween a fixture and the soil-pipe or house-drain which is
not trapped.
A little reflection will show that provision has been
made for each of the five specified requisitions for the
system, and that if the foregoing specifications are observed,
the air in the soil-pipes will be almost as pure as that of
the house itself, and the absorption of foul gases by the
water in the house-traps and their subsequent dispersion
into the atmosphere of the house will be almost impossible.
But there must always be both an inlet and an outlet for
air to the house-drain and soil-pipe, and free communica-
tion between these; otherwise the air in the soil-pipe can-
not be changed, and foul gases will accumulate, which by
308 A MANUAL OF HYGIENE AND SANITATION.
their pressure might overcome the seal of some of the
traps.
Traps are " appliances placed between house conven-
iences (fixtures) and soil-pipes and drains or sewers, to
FIG. 43. FIG. 44.
These illustrations show how a uniform calibre prevents the accumulation of
dirt in a trap, and how angles and corners favor such accumulations.
prevent sewer-gas gaining an entrance into the house."
Most traps are too complicated. The simpler a trap
the better, provided it have sufficient seal. Mechanical
appliances are liable to become clogged and not to fit
FIG. 45.
S, or siphon, trap, with opening for ventilation pipe.
tightly, thus allowing the passage of sewer-air. The S,
or siphon, trap is as simple as any, is of uniform diameter
throughout, has no corners or projections to catch dirt, and
THE REMOVAL AND DISPOSAL OF SEWAGE. 309
is thoroughly cleansed by each fair flow of water through
it. The value of a trap does not depend so much on the
amount of water it contains as on the depth of the seal.
On account of evaporation the water-seal of a trap soon
FIG. 46.
FIG. 47.
Bell trap.
CudelPs trap.
becomes lessened or destroyed, unless its fixture be in fre-
quent use; it is, therefore, advisable to have as few fixtures
of any kind in the house as the comfort or convenience of
the inmates will allow. So, also, if a house is to be left
FIG. 48.
FIG. 49.
Bower's trap.
Pot trap (for kitchen sinks, etc.).
unoccupied for a time, it is well to cover the water in the
traps with oil or glycerin to prevent the evaporation of
the former.
310
MANUAL OF HYGIENE AND SANITATION.
The seal of a trap may be broken by siphonage, either
by a rush of water through it from its own fixture, or by
a rush down the soil-pipe from a fixture higher up, and
this is especially liable to occur if the trap be some dis-
tance from the soil-pipe, or if the fixtures above discharge
a large amount of water at once. To prevent this open-
ings are sometimes made at the top of the traps on the
FIG. 50.
McClellan's anti siphon attachment. Sectional view of vent, with cup lifted
out of the mercury by the inflowing current -of air, indicated by the arrows-
(ROH£.)
side next the waste- or soil-pipe and connected with vent-
pipes, which should open into the soil-pipe above the
entrance of the waste-pipe from the highest fixture, or into
a separate ventilation-pipe. But this greatly increases the
expense, and as the vent-pipes, to be efficient, must be
almost two inches in diameter, they also favor evaporation
from the trap. If the trap is properly constructed, the
THE REMOVAL AND DISPOSAL OF SEWAGE. 3H
soil-pipe of proper size and height, and if the fixtures be
placed as near the soil-pipe as possible, there will be but
little danger of siphonage occurring. Where it does occur,
McClellan's anti-siphon attachment is said to work advan-
tageously, being inexpensive and permitting a free ingress
of air to the trap, but no egress of air from the soil-pipe
into the house. It is also said that if the fixture be
connected to the soil-pipe by a divergent opening, siphon-
age will be less likely to occur.
All waste-pipes, soil-pipes, and house-drains should be
tested before use by closing all openings and forcing in air
to a pressure of at least thrity pounds to the square inch.
Leaks may be detected by plugging the lower openings
and filling the pipes with water, or by pouring an ounce
of oil of peppermint into the highest fixture and quickly
following this with several gallons of hot water, the heat
volatilizing the oil, whose odor escapes at every opening
in the pipes unprotected by a trap or water-seal. The
heat imparted by the hot water will also help to trace out
hidden soil-pipes.
All fixtures should be exposed to the free ventilation of
air underneath and about them, and water-closets and
washstands should not be closed in with carpentry work.
Traps should also, if possible, be where they may be
opened and inspected at any time. Under each fixture
there should be a drip-safe to catch any leakage or
overflow of water, but the pipes, if there be any, leading
from these should never empty into waste- or soil-pipes;
they should lead preferably to the open air, and not to
the cellar, as the air in most cellars is bad, and thus gains
access to the house. Even if these drip-safe pipes are
trapped and open into the soil-pipe, the water in the trap
is replenished so rarely that evaporation soon destroys the
312 A MANUAL OF HYGIENE AND SANITATION.
seal and allows the air to pass from the soil-pipe into the
house.
8
The overflow pipe of old-fashioned wash stands and
bath-tubs is objectionable, as it collects dirt of all kinds,
THE REMOVAL AND DISPOSAL OF SEWAGE. 313
soap, epithelium, etc., and it is almost impossible to clean
it. Besides, it will often be found opening into the waste-
pipe below the trap, thus allowing the free passage of sewer-
air into the room. When new fixtures are being put in
they should, preferably, be such as make use of the stand-
pipe principle in the stoppers, and that have no separate
or concealed overflow-pipe or outlet.
Water-closets. The requisites for a good water-closet
are: that it does not allow the escape of sewer-air from
FIG. 52.
Pan closet.
the soil-pipes into the house; that it is thoroughly and
easily cleaned each time after use; that there are no
hidden parts in which filth can collect, or which cannot
be readily cleaned; that the flushing or washing out of a
closet be done in such a way that dirt or spray be not
thrown into the air of the room; that there be sufficient
water-supply to wash out the bowl and trap each time, and
to refill them to the proper level; that the trap itself is
314 A MANUAL OF HYGIENE AND SANITATION.
not siphoned or left empty by a discharge of water from
this or another fixture.
Of the different kinds of water-closets the pan and the
valve closets are the oldest and the worst, and should not
be used. They consist of a receiving bowl, the bottom of
which opens into a swinging pan or is closed by a valve.
The pan or valve and the lower part of the receiving bowl
are enclosed in a larger bowl, the container, connected
with the soil-pipe and trap. The depth of water in the
FIG. 53.
Valve closet.
receiving bowl is regulated by the depth of the pan in
pan closets, and in valve closets by the location of an
overflow outlet. In both kinds the contents of the receiv-
ing bowl are discharged into the container by the tipping
of the pan or valve, and, consequently, the sides of the
container, as well as the under side of the pan or valve,
soon become thickly coated with filth. This, being
hidden, accumulates, decomposes, and contaminates the
air in the container, which air is of necessity discharged
THE REMOVAL AND DISPOSAL OF SEWAGE. 315
into the room as often as it is displaced by the contents of
the receiving bowl. In valve closets the overflow-pipe
from the receiver furnishes an additional way by which
the foul air may pass from the container into the atmos-
phere of the room. It needs no argument to show that
these closets are decidedly dangerous to health.
Plug or plunger closets are those in which the outlet
above the trap is stoppered by a plunger, this being
usually in a chamber at the side of the receiving bowl.
FIG. 54.
Plug or plunger closet.
The bowl and side chamber holding a considerable quan-
tity of water, the trap is well flushed out each time of use;
but the side chamber and plunger, being hidden and not
easily cleaned, soon become coated with filth and danger-
ous to health, as there is nothing to prevent the air from
passing from this chamber into the room. Moreover, the
plug may not close the opening completely, thus allowing
a continual waste of water. A trapped overflow-pipe in
the plunger keeps the closet from overflowing.
316 ^ MANUAL OF HYGIENE AND SANITATION.
Hopper closets consist simply of a bowl connected below
with an ordinary trap, and, as there is nothing to get out
of order, this kind is theoretically one of the best. The
objection to long hoppers is that dirt is apt to stick to the
sides and become offensive, but this can be prevented if it
is so arranged that water begins to flow down the sides as
soon as the closet is put to use, thus preventing adhesion.
Short hoppers have not this objection, as the feces fall
directly into the water in the bowl and are carried out
FIG. 55.
Short-hopper closet.
through the trap as the bosvl is flushed. All water-closets
should have a flushing rim encircling the top, so that all
sides of the bowl may be washed down and cleansed each
time the closet is used.
Wash-out closets retain considerable water in the bowl,
and are emptied by a strong flush of water from the flush-
ing rim. They are simple, do not readily get out of order,
and are much in favor at the present time. As they are
a modification of the short-hopper closet, so is the siphon
closet a modification of the wash-out.
In the siphon closets the contents of the bowl and trap
are lifted out by a siphonic action, and then the bowl and
THE REMOVAL AND DISPOSAL OF SEWAGE. 317.
trap are refilled, as in the case of wash-out closets, by an
after flush. In the Dececo closet — a siphon closet — use
is made of the principle involved in the Field flush tank.
Hopper, wash-out, and siphon closets should be supplied
FIG. 56.
Wash-out water-closet. (PARKES.)
from water-closet cisterns, which should give down a cer-
tain and sufficient volume of water with only a short pull
on the chain. The bowl and trap should also be refilled
from the cistern after use.
*
PIG. 57.
Dececo siphon closet. (PAKKES.)
Water-closets should not be connected directly to the
water-supply pipes of the house, as air from the closets
may be sucked into them at times when the water-supply
is cut off, and the water afterward contaminated by it.
.318
MANUAL OF HYGIENE AND SANITATION.
But this is hard to avoid in pan, valve, or plug closets,
and is another serious objection to their use.
Vent-pipes from the bowl and seat of water-closets must
be large, and must not open into the soil-pipe but into the
open air; they must not open near a window nor any place
from which air is taken into the house, but may open into
a flue which is constantly heated, as a kitchen chimney, or
may themselves be heated and have a current maintained
in them by a small lamp or gas-jet. In this way the
room in which a water-closet is located may be effectively
ventilated.
Water-closets should never be placed in dark closets,
nor in bedrooms or living-rooms, but should always be in
separate rooms that have free communication with the
open air by means of a large window or by a ventilating
shaft of at least four square feet area throughout its entire
length. It is also advisable that bedrooms should not
FIG. 58.
Automatic ejector for disinfecting traps, water-closets, etc.
communicate directly with bath-rooms, etc., containing
water-closets, unless there is every assurance that the
closet and plumbing connected with it are first class in
every particular.
THE REMOVAL AND DISPOSAL OF SEWAGE. 319
A recent device which is intended for attachment to the
flush-pipes of water-closets and to the waste-pipes of other
fixtures between them and their traps, automatically dis-
charges with each flow of water through the respective
pipes a sufficient quantity of a disinfectant to destroy and
prevent all growth of micro-organisms in the traps or
their contents. This, when used, will aid not only in
preventing the escape of harmful or disagreeable gases
into the house, but will render the addition of disease-
germs to the contents of the public sewer almost impos-
sible.
Sewers. These are the conduits provided to receive
and convey the contents of house- and other drains to the
place of final disposal or discharge. They may be of
either of two kinds — "combined" or "separate" Sewers
of the former class, which have heretofore been most com-
monly used in this country, are constructed to carry off
all kinds of sewage, the waste liquids, etc., from factories,
street washings, and the surplus rain-water of the district
drained by them. As this necessitates a size and capacity
sufficient to receive the greatest probable rainfall upon the
area drained, in addition to the sewage, it is evident that
the depth of the normal daily flow of the latter will be so
shallow and the current so sluggish as greatly to favor the
settling of the solid and semi-solid constituents, the obstruc-
tion of the sewers, and the development of bacteria and
sewer-gas. To ob.viate this and to insure a more rapid
flow by keeping the depth of sewage as great as possible,
the smaller conduits, at least, are generally made ovoid in
section, the smaller end, of course, being downward.
"Combined77 sewers are not only more expensive to con-
struct and to keep in repair than those of the separate sys-
tem, but greater care must be had to see that they are at all
320 A MANUAL OF HYGIENE AND SANITATION.
times properly ventilated. The main advantage claimed
for them is that the expense of constructing separate con-
duits for factory wastes, street washings, and the excess of
rain-water is avoided; but this is a doubtful one, both in
respect to economy and sanitation.
PIG. 59.
Section of ovoid sewer of " combined " system.
The ventilation of sewers of this kind is usually suffici-
ently provided for by the inlets for street washings and rain-
water, located at street corners, etc. ; but if these are not
close enough together to keep the sewer atmosphere con-
stantly changing and reasonably pure, other ventilation
openings must be made. But in all cases the air from sewers
THE REMOVAL AND DISPOSAL OF SEWAGE. 321
of the combined system must be excluded from house-
drains, etc., by the traps which have already been described.
To the sewers of the " separate7' system only the sew-
age proper from dwellings and, occasionally, from small
factories, is admitted, the rain-, surface- and soil-waters
being removed by other drains or channels. The advan-
tages of this system, which is now indorsed by almost all
sanitarians, are that the volume of sewage to be carried is
comparatively small and constant, and that it can be cal-
culated very approximately from the daily water-supply
and population; that the cost of construction is much less
than that of sewers of the combined system, and that,
while it is perfectly available and satisfactory for large
cities, it is the only one that small communities would
consider or can afford; that the sewage is more concen-
trated and uniform in composition, and can thus be better
utilized as a fertilizer or disposed of in whatever manner
may be desirable; that the sewers, having smaller and
smoother walls, are more frequently and effectually
flushed, and that they are more completely ventilated and
altogether better suited to the work to be performed.
The disadvantages of sewers of this class are that a com-
munity must have two sets of drains, one for sewage
and the other for rain, street, and factory waters, and that
after a long dry season the street washings, etc., may be
very foul; but these are outweighed by the advantages
above mentioned.
" No sewer of this system should be more than six
inches in diameter until it and its branches have accumu-
lated a sufficient flow at the hour of greatest use to fill
this size half full, because the use of a larger size is waste-
ful and because ventilation becomes less complete as the
size increases. The size should be increased gradually and
21
322 A MANUAL OF HYGIENE AND SANITATION.
only so rapidly as is necessary by the filling of the sewer
half full at the hour of greatest flow; and the upper end
of eacli branch sewer should be provided with an auto-
matic flush-tank of sufficient capacity to secure the thor-
ough daily cleansing of so much of the conduit as from
the limited flow is liable to deposit solid matters by the
way."
FIG. 60.
Field's annular siphon flush-tank. (PARKES.)
There should be no traps between house-drains and sewers
of the separate system, since, having no rain-water inlets,
the latter would otherwise have no openings for ventilation.
Moreover, since the ' ( separate ' ' sewers are so regularly
and thoroughly flushed, the air in them is not likely to be
so impure, and there is not the same reason for excluding
it from the house-drains, etc., as there is regarding the
air from "combined" sewers. The junctions of house-
drains with sewers of the separate system should be by
divergent openings, so that the air may pass freely into
the drain as the sewage empties into the sewer.
Should one desire, however, to separate his house-drain
from the public sewer by means of a trap, and thus pre-
THE REMOVAL AND DISPOSAL OF SEWAGE. 323
vent the ingress of sewer-air into his premises, the venti-
lation of the sewer can be secured by providing a vent-
pipe between the trap and the sewer. But in no case must
the inlet-pipe on the other side of the trap, between it
and the house, be omitted; nor should the two air-pipes
be so near together that air from the former will be likely
to be drawn into the latter.
All sewers should be laid on a good foundation with
sufficient fall to give at least a velocity of two feet per
second to the flow. If made of bricks they should be
laid in a mortar made of cement and sharp sand, and all
sewers should be as smooth as possible inside to prevent
the arrest of particles of sewage. Sewers of the com-
bined system should not be pervious to the soil- water, as
the liquid sewage is as apt to pass from them to the
soil and to pollute it dangerously, as the soil-water is
to pass into the sewers. But the rain-water drains of
the separate system may also be employed to drain the
subsoil.
The ultimate disposal of sewage is a matter of con-
siderable importance which commonly does not receive the
attention it deserves. The usual method in this country
of discharging the sewage into a running stream is repre-
hensible, because the natural purification of a water thus
contaminated must always be slow and more or less uncer-
tain, and because the risk to those using the polluted water
must be a constantly increasing one. Where the district
drained and supplied by the stream is a sparsely settled
one, and where the volume of fresh or running water is
very large in proportion to the quantity of pollution it re-
ceives, the objections to the disposal of sewage in this way
may be theoretical rather than practical; but as the popu-
lation increases and the ratio of pure water to filth de-
324 A MANUAL OF HYGIENE AND SANITATION.
creases beyond certain limits, the question becomes more
serious and pertinent.
Other methods of sewage disposal resemble closely those
already described for the purification of water, in that they
make use of subsidence, chemical treatment, and filtration.
The sewage is collected in large tanks, with or without the
addition of certain chemicals, such as lime, alum, and sul-
phate of iron, to increase the precipitation, and the sus-
pended impurities are allowed to settle to the bottom of the
tanks, whence they can be removed, squeezed partially dry
in hydraulic presses, and either disposed of as a fertilizer or
cremated. The clear effluent or liquid part of the sewage
may be allowed to flow at once from the settling tanks into
a convenient watercourse, provided it is there well diluted,
or may be filtered through an area of porous soil or through
prepared filter beds. If the filtration is properly done the
filtrate will contain nothing harmful, and may be allowed
to flow where it will without danger. A properly pre-
pared filter bed of twelve inches of sand upon eighteen
inches of gravel or magnetic carbide of iron, with an area
of one acre, is said to be able to purify from one to two
million gallons of clarified — effluent — sewage in twenty-
four hours.
Other ways in which sewage may be disposed of are by
intermittent downward filtration, by irrigation, and by
sub-irrigation. The soil to be used for this purpose
should be porous and loamy; if clay, it should be well
broken up and mixed with ashes; sand does not do well,
especially at first in these methods. The sewage impuri-
ties are removed partly by mechanical filtration, but espe-
cially by oxidation, the latter being due partly to the air
in the interstices of the soil, but chiefly to the saprophytic
bacteria, which rapidly convert the organic impurities into
THE REMOVAL AND DISPOSAL OF SEWAGE. 325
nitrates and nitrites. In each of these methods the sewage
should be applied intermittently, so that the air in the soil
may be periodically renewed.
By intermittent filtration we mean " the concentration
of sewage at short intervals, on an area of specially chosen
porous ground, as small as will absorb and cleanse it; not
excluding vegetation, but making the produce of secondary
importance. The intermittency of application is a sine
qua non even in suitably constituted soils, wherever com-
plete success is aimed at/7 The land should be levelled
and underd rained with tile drains at the depth of five
or six feet, and should be divided into four parts, no
part to receive sewage for more than six hours. An
acre of properly prepared soil will thus dispose of the
crude sewage of 1000, or the clarified sewage of 5000
people.
Irrigation means "the distribution of sewage over a
large surface of ordinary agricultural ground, having in
view a maximum growth of vegetation, consistently with
due purification, for the amount of sewage supplied/7
Sub-irrigation is a modification of this, the sewage being
delivered through porous drains a few inches beneath the
surface of the soil. Unless very porous, the land should
be underdrained; it should also be levelled to prevent the
sewage flowing off the surface too rapidly. The under-
drains need not be nearly so close together, however, as in
the intermittent filtration system. The crops raised on
irrigation farms are perfectly healthful in every respect,
and there can be no reasonable objection to their use; there
would be decided objection, however, to watering the
vegetables with sewage water.
The sewage of from one hundred to three hundred per-
sons per acre of irrigation area can be safely disposed of
326 A MANUAL OF HYGIENE AND SANITATION.
by this method, and it is to be especially recommended for
isolated houses, for small communities, or for charitable or
other State institutions.
Electricity has also been suggested as an agency for the
purification of sewage, but seems to be still too expensive
for the purpose.
CHAPTER XII.
VITAL STATISTICS.
SCIENCE is classified knowledge. By arranging known
facts and units into groups, and considering them from
different points of view, we discover the scope of a partic-
ular science, and are also led to the discovery of new facts.
In hygiene it is necessary to have this classification of
facts to know what progress we are making, for the true
test of any sanitary procedure is its efficacy in preserving
health and preventing disease, and we cannot know
whether it is efficient or not unless we tabulate and study
the results and at the same time eliminate disturbing fac-
tors. In this connection it is to be noted that our facts
must be accurate and derived from sufficient experience,
and that the disturbing factors are especially liable to be
numerous.
It is evident that we may study disease by direct obser-
vation at the bedside and at the post-mortem table, or by
experiment; and while our knowledge in the past has been
gained principally by the former method, we now, since
the advent of modern bacteriology, may further investi-
gate many diseases by reproducing them in susceptible
animals. In this way we soon learn that some diseases
are much more preventable than others, and we endeavor
to discover the respective causes and predisposing condi-
tions of each that we may the more readily estimate their
effects and take measures to restrict and prevent their
action .
Our observations may be of two kinds : 1. By noting
328 ^ MANUAL OF HYGIENE AND SANITATION.
and comparing individual cases, or by following the track
of a particular outbreak or epidemic. 2. By observing
large classes and groups of men, which necessitates a record
of births, marriages, diseases, and deaths. The considera-
tion of such records constitutes the study of vital statistics,
the most important object of which is, as Dr. Billings says,
" to give warning of the undue increase of disease or death
presumed to be due to preventable cause, and also to indi-
cate the localities in which sanitary effort is most desirable
and most likely to be of use." The reader will also notice
how the study of vital statistics broadens out into the
science of demography — the study of the life of people
and communities.
At this point it will be well to note certain elementary
principles which must be observed in any statistical in-
quiry, in order that the results of that inquiry may have
any value whatever. These are:
1. Our facts, or numerical units , must have precise, defi-
nite, and constant characteristics. For example, in tabu-
lating the death- or sick-rate from typhoid fever, every case
used in the calculation must be accurately diagnosed
and must be undoubtedly one of that disease. If there
is any doubt as to preciseness, it is better to omit that unit.
2. The units are to be arranged into groups. These
groups must have dividing characteristics so definite that
there can be no doubt into which group each unit will
come. No unit must be in more than one group at one
time. It is difficult to group complex facts so as to prop-
erly analyze them and to discover all possible phases.
3. Having decided and arranged the groups, we must
have a constant numerical standard by which the relation
of the various groups to the total units may be expressed.
It is generally 100 or some multiple of 100.
VITAL STATISTICS. 329
4. We must determine the variation in the proportion
or relation of the component groups to the whole in similar
series of cases. While only an approximation to an inva-
riable proportion may be had in any one series, it may be
shown mathematically that as the number of units in the
series increase there is a greater probability that the pro-
portions will remain the same, and that we may calculate
the limits of variation by Poisson's formula, as follows:
If, in the formula m -f- n =• q, m be the number of units
in one group and n the number in the other, the propor-
tion of m to q will be — , and of n to q, U , and these propor-
tions will vary in succeeding series within the limits indi-
cated by 2 + 1 - —1 Consequently, the greater the value
__
of <?, the less will be that of 2 -y — — , or the limit of varia-
#3
- m i n
tion from and _.
q q
Example : Suppose that in a series of 1000 cases of
typhoid fever 700 recover; then, according to the above
formula, the limit of variation in the next series of 1000
similar cases would be 40, and the recoveries would be
between 660 and 740.
The arithmetical mean is usually employed in medical
inquiries, though the increase in population is estimated
by geometrical progression. The probable error or vari-
ation from the arithmetical mean is about two-thirds
(0.6745) of the mean error, which latter is the mean of the
mean error in excess and the mean error in deficiency. The
mean error in excess is the difference between the mean of
the series and the mean of all the units of the series above
the mean. The mean error in deficiency is the difference
330
MANUAL OF HYGIENE AND SANITATION.
between the mean of the series and the mean of the units
below the mean.
The relative value of two series is as the reciprocals of
the squares of their probable errors. Thus if the probable
error of series A is 10 per cent, and that of B is 2 per
cent., the value of A to B will be as y^ to ^, or B will
be twenty-five times as valuable as A.
FIG. 61.
Graphic chart, showing percentages of typhoid-fever deaths in total mortality
in four cities. Unbroken line, Chicago ; lower line, New York ; short dashes,
Philadelphia ; long dashes, Boston.
The relative value of two or more series is also as the
square roots of the numbers of units in the respective
series. From the above it is evident that the results from
an average cannot be absolutely applied to any particular
case, for there is always the chance of such variation as
may be determined by Poisson's formula or by the estima-
tion of the probable error. We apply averages to the
aggregates of facts, and they will approach exactitude if
VITAL STATISTICS. 331
they are founded on a sufficient number of facts. We
must be careful in estimating the value of means and aver-
ages and in giving credit or blame accordingly. Dr. Guy
says : " Averages are numerical expressions of probabili-
ties; extreme values are expressions of possibilities.7'
Statistical results are frequently expressed by graphic
representations (see Fig. 61), and these are very valuable,
especially for class or similar demonstration.
The numerical units employed in the study and the cal-
culations of vital statistics are persons living and persons
dead, and the groups into which these units are classified
are characterized by such distinctions as age, sex, occupa-
tion, locality, etc. The sources from which we derive our
information regarding these units are two, viz., the census
or count, which every civilized country makes period-
ically, and the returns of births, marriages, deaths, and
cases of contagious disease made to local governing sani-
tary bodies, such as boards of health, etc. These latter
returns localize the units and help especially in the classi-
fication, in which locality is a factor.
The census returns give not only the population, but
particulars as to sex, age, race, occupation, etc. Of these
the age-record is most important, as the death-rate varies
most according to age.
The natural increment of a population is the excess of
births over deaths, but the actual increment differs from
this, however, according to the difference between emigra-
tion and immigration. And as the rate of increase does
not always remain the same, estimates of population at
times other than of the census cannot be exactly accurate.
Thus, we may have a lowered death-rate and yet a decrease
in both the natural and actual increment, owing to a greatly
lowered birth-rate and to increased emigration, both of
332 A MANUAL OF HYGIENE AND SANITATION.
which may be primarily due to a long period of oppression
or financial distress. However, to estimate the population
for times other than the census year, we assume that the
rate of increase, whether positive or negative, that pre-
vailed between the last two census enumerations, will con-
tinue until the next is taken.
Now, as populations increase in regular geometrical
progression when the rate of increase is constant, which
we assume, it can readily be shown that log. R = — (log.
P' — log. P), where R is the annual ratio of increase, P the
population of the census before the last, and P' the popu-
lation of the last census. If we now multiply the log. of
R, the annual ratio of increase, by the number of years
since the last census, and add to it the log. of the last
census (log. P'), we will have the log. of the population
at the middle of the present year — e. g. ,
8 (log. of the pop. 1890 — log. pop. 1880)
~IO~
+ log. pop. 1890 = log. of the population on June 30,
1898.
For the reasons already given, such an estimate will
not be absolutely accurate, and it would, consequently, be
well to have a census taken every five years for certain
data. The more accurate the estimate for any year hap-
pens to be, the more reliable will be the statistical results.
It is also to be noted that in this country the census is
taken at the middle of the year, and that death-rates, etc.,
are based on the population estimated, as above, for the
middle of the given year.
We may also estimate the population from the number
of houses and use this as a check on the above estimate.
The number of persons living in each house averages about
VITAL STATISTICS. 333
the same for each city, but differs for different cities.
Local authorities always tend to overestimate the popula-
tion, and a police census is invariably too high. Another
method of approximately estimating the population in
small and slowly increasing districts is to add to the pop-
ulation of the last census one-tenth of the difference
between it and the population of the preceding census for
every year since the last census.
As has been stated, we get the number of births, mar-
riages, deaths, etc., from the registration records, the
proper data being furnished to the registration bureau by
duly authorized persons. For instance, the law should
require a burial permit for each death in order to identify
the person and to guard against criminal acts or neglect,
and the death certificate on which the burial permit is
issued should give the name, sex, color, age, occupation,
and especially the cause of death of the deceased. The
diagnosis concerning this last item should be as correct as
possible, and the primary as well as the secondary cause
of death should be given. And while it is difficult to
determine the actual cause of death in many cases without
a post-mortem examination, there is, fortunately, not much
uncertainty usually in diagnosing the diseases of which
we most want statistical information, especially the so-
called preventable or infectious diseases.
As a consequence of the above, the certificate as to the
cause of death will need to be signed by some one com-
petent to determine that cause, viz., by an educated physi-
cian; and it is, therefore, necessary that the State should
define who is and who is not an " educated physician. "
And as this information and the other required returns
which the physician makes, as well as his professional
services in general, are for the sake and benefit of the
334 A MANUAL OF HYGIENE AND SANITATION.
citizens of the State, it is evidently to the State's interest
that it be very careful and explicit as to the qualifications
of the physicians whom it allows to practise within its
borders.
Another reason for the enforced return of a certificate
and the issuance of a burial permit for every death is,
that that is about the only way in which it is possible to
secure a record of all the deaths. Any system for col-
lecting the list of deaths only at the end of the year will
lose from 25 to 40 per cent, of the number.
The gross death-rate varies with the size of the com-
munity. Newly settled communities have a lower death-
rate than older ones, because the proportion of adults is
larger and of children smaller in the former. With
large communities and short periods the probabilities of
error are very great, and the longer the period the less
likelihood of error. Birth-, marriage-, and death-rates
are usually calculated as rates per thousand of the popula-
tion living at tha middle of the given year, and are deter-
mined by multiplying the number of births, marriages, or
deaths by 1000, and dividing the product by the population.
Fair death-rates are 9 to 16 per 1000 in rural districts
and small villages; 14 to 18 per 1000 in towns of 5000
to 20,000; 17 to 20 in cities of 25,000 to 100,000, and
18 to 21 in cities over 100,000. If the death-rates are
much lower than this, the chances are that the population
has been overestimated or that all deaths have not been
recorded. If more than this, there is probably some
special cause for the high mortality.
In statistical computations we must exclude the popula-
tions and deaths in hospitals, prisons, etc. , except for such
of the inmates as belong to the district in which such
institution is located.
VITAL STATISTICS. 335
To find the weekly or daily death-rate, the number of
deaths for the week or day must be divided by the so-
called weekly or daily population : the weekly population =
The monthly population equals the daily population mul-
tiplied by the number of days in the month.
The zymotic death-rate is the rate from the seven princi-
pal zymotic or infectious diseases, viz., smallpox, measles,
scarlatina, diphtheria, whooping-cough, fever (typhoid,
typhus, or other continued fever), and diarrhoea.1 It is
given per 1000 of population, and in the same way we can
give the special rate for any particular disease. For ex-
ample, the zymotic death-rate for England and Wales
from 1861 till 1870 was 4.11, for 1871-80 it was 3.36, and
for 1881-90, 2.30; a striking proof of the decided benefits
following proper attention to hygiene and sanitation.
The mortality from certain diseases is affected by age,
sex, race, occupation, density of population, seasons,
cyclical changes, etc.
Contrary to the general rule, the rate of infant mortality
is not expressed per thousand of population, but measured
by the proportion of deaths of infants under one year to
the births registered in that year, and is determined by
multiplying the number of deaths by 1000 and dividing
the product by the number of births.
The infant mortality-rate is always high, owing to vari-
ous causes; viz., early marriages and weakly parents,
hereditary tendencies or diatheses, insanitary surround-
ings and unfavorable social conditions, improper feeding,
insufficient clothing, infant life insurance, etc.
1 Wilson : Hahd-Book of Hygiene, p. 566.
336 A MANUAL OF HYGIENE AND SANITATION.
Death-rates vary greatly for the different ages, being
much higher for the first five years of life. For this
reason, it is well to express the death-rate of children
tinder five as the rate per thousand of the children under
that age, rather than as a percentage of the total number
of deaths. Otherwise, a town with a large number of
children might apparently have an abnormally high death-
rate. There might also be a difference in the death-rates
of two localities due to sex-distribution, for the sexes differ
in their susceptibility and resistance to the various dis-
eases. More boys are born everywhere than girls, but
more males die than females, so that the tendency is to a
preponderance of the latter, except in newly settled coun-
tries or localities. Age- and sex-distribution favor a low
mortality in rapidly increasing towns, new localities, and
manufacturing districts; in rural districts they tend to
increase the death-rate.
Consequently, when the death-rates of two or more
towns or localities are to be compared, there must be cor-
rections for age- and sex-distribution. The mean annual
death-rate of the country for the decade preceding the last
census for each age and sex is applied to the town or dis-
trict, with age- and sex-distribution according to the last
census. The total number of deaths thus calculated, mul-
tiplied by 1000, and divided by the population of the last
census, gives the standard death-rate of that town. The
mean annual death-rate of the country divided by the
standard death-rate gives the factor for correction, which
being multiplied by the recorded death-rate of any year
gives the corrected death-rate. The comparative mortality
figure is determined by multiplying the corrected local
death-rate by 1000 and dividing by the death-rate for the
whole country, and only indicates that the same popula-
VITAL STATISTICS. 337
tion which gave 1000 deaths in the whole country gave or
would have given so many deaths in the town or district
in question.
The morbidity- or sick-rate of a community is difficult
to estimate, since there is usually no complete record and
registration of cases of disease. Where returns are re-
quired to be made of the infectious diseases, the morbidity
due to them may be determined in the same way as the
mortality for the locality. It is estimated that there is a
total of about two years' sickness in a community for
every death, and members of beneficial societies are said
to average about one and one-half weeks7 sickness annu-
ally. In this connection, the following definitions are
given of terms that are employed in discussions of vital
statics, especially in relation to longevity:
The mean age at death of a population is the average
age at which death occurs in that population, and is indi-
cated by the total of the ages at death divided by the
number of deaths. Inasmuch as it depends largely on
the age-distribution of the population, it is neither a good
test of longevity nor of sanitary conditions, except when
it is calculated or taken from life-tables for an entire
generation.
The probable duration of life is the age at which any
number of children born will be reduced one-half, the
chances thus being even that each will survive to that age.
For a million children the probable duration of life is
for males less than forty-five years; for females, forty-
seven years.
The mean duration of life is the same as the mean age
at death when the population is stationary as to age- and
sex-distribution. Otherwise, it is indicated by the mean
after-lifetime.
338 A MANUAL OF HYGIENE AND SANITATION.
The expectation of life is the mean after-lifetime of a
person at any age, as indicated by a life-table, or, in other
words, it is the average number of years which persons of
that age continue to live. At birth it is identical with
the mean duration of life, and " as applied to communi-
ties, it is the mean lifetime of a generation of persons
traced by the life-table method from birth to death, and is
the only true test of the health of populations." Accord-
ing to Dr. Farr, " a life-table is a barometer which indi-
cates the exact measure of the duration of life under given
Circumstances, and is indispensable in gauging the influ-
ence of sanitary or insanitary conditions."
The essential factors of a life-table are the number and
ages of the living and the number and ages of those that
die, and these factors are obtained from the mean popula-
tion for each age and sex and from the total death returns
between two censuses.
CHAPTER XIII.
THE EXAMINATION OF AIR, WATER, AND FOOD.
IN this final chapter the author has endeavored to
arrange a series of methods for the examination or analy-
sis of the subjects respectively considered, in such a manner
that any one who has had a little laboratory experience may
be enabled to determine their hygienic condition, sanitary
influence or degree of purity, and this at the cost of a
minimum of time and expense.
The methods outlined have been selected from a variety
of sources, and some have been specially modified for the
purpose; so that while it is not claimed that they will give
the absolutely accurate results desired by the professional
bacteriologist or chemist, it is believed that, if carefully
carried out, they will not fail to yield the information
sought for, viz., whether the sample of air, water, or food
examined is sanitarily pure or safe for use within the
accepted limits.
Only such apparatus is to be used as can be readily
obtained or improvised without much expense, and every
effort has been made to render everything clear to the
student and reader, so that he may not hesitate to under-
take the necessary investigation whenever occasion requires
or an opportunity offers.
For further details regarding any of the methods, should
these be found necessary, reference may be made to the
text-books indicated, as they will render clear any points
that may here seem uncertain or abstruse.
340 A MANUAL OF HYGIENE AND SANITATION.
Air.
The solid impurities in the atmosphere may be collected
for microscopical examination as follows: Tightly cork a
large glass funnel and fill it with cracked ice. As the aque-
ous vapor of the air condenses on the exterior, the dust par-
ticles adhere to the moistened glass, and are carried down
by the condensed water into a vessel placed below, in
which they are allowed to settle. From this they are
transferred by means of a pipette to clean slides and
examined under the microscope. Dr. Dixon's apparatus
may often be used advantageously, especially where it is
desired to examine the dust in the air of a number of
localities within a short time.
To make a qualitative bacteriological examination the
air may be drawn through sterilized glass tubes coated
interiorly with gelatin. Bacteria and their spores, moulds,
etc., adhere to this coating, and from each individual or
group of individuals colonies develop, from which pure
cultures and subsequent bacteriological experiments may
be made; or the sterilized gelatine may be exposed in flat
(Petri) dishes to the air for a short time to allow the bac-
teria, etc., to fall on the surface. The tubes or dishes are
then covered and set aside to allow the colonies to develop.
To make a quantitative bacteriological examination a
known quantity of air may be drawn through a tube filled
with sterilized granulated sugar. The sugar is then trans-
ferred to tubes or flasks of melted and sterilized gelatine,
and dissolves and leaves the bacteria, etc., free to develop
in the gelatine, which may be poured out before cooling
upon sterilized glass plates or flat Petri dishes. A tem-
perature just sufficient to melt the gelatine will not be too
high to harm the bacteria.
The number of colonies that develop may be assumed
EXAMINATION OF AIR, WATER, AND FOOD. 341
to represent the number of living micro-organisms in the
volume of air drawn through the tube or that fell in the
dishes.
Test for Carbonic-acid Gas, CO2. Prof. Boom's
Modification of Wolpert's Method. Make a mark on any
test-tube, say one inch from the bottom. Fix the bulb of
an atomizer to a small glass capillary tube, sufficiently
long to reach to the bottom of the test-tube, and in such
a manner that a definite quantity of air is forced from the
bulb through the tube at each compression. To use: Fill
the test-tube exactly to the mark with a saturated solution
of lime-water, take the apparatus into the out-door air and
find put how many compressions of the bulb are needed,
driving the air slowly through the lime-water each time,
to make the lime-water just turbid enough to obscure a
pencil-mark on white paper placed beneath the test-tube
and viewed from above.
Then rinse out the test-tube, fill exactly to the mark
again with lime-water, and repeat the process in the room
the air of which is to be examined. We then assume that
the out-door air contains the normal amount of CO2, 0.04
per cent, (unless we happen to know the actual amount in
the atmosphere at the time), and estimate the percentage
of CO2 in the air of the room by the following proportion :
The number of compressions of the bulb required in
the outer air : the number of compressions required in
the room : : x : 0.04; x = the percentage of CO2 in the
air of the room. If the actual percentage of CO2 in the
outer air is known, substitute this for the 0.04 per cent,
in the formula. Care must be taken in using this device
not to draw any of the lime-water up into the bulb.
A Modification of Angus Smith's Method. To a mode-
rately large, wide-mouth bottle (one quart) fit a perforated
342 A MANUAL OF HYGIENE AND SANITATION.
rubber stopper, the perforation being just large enough
to admit the tip of a 1 c.c. pipette, fill the bottle with
the air of the room by filling it with water and then
emptying it in the room; fit in the stopper and introduce
1 c.c. at a time of a standardized alkaline solution, slightly
colored with a few drops of a neutral alcoholic solution of
phenol phthaleine; close the perforation with a piece of glass
rod and shake the bottle well after each addition of the
alkali, noting when the color ceases to be discharged by the
CO2 of the contained air. Then, since the quantity used of
the alkali solution indicates a certain definite amount of CO2:
The number of c.c. used multiplied by the amount of C02
each c.c. represents, multiplied by 100, and divided by the
capacity of the bottle in c.c. less the number of c.c. of solution
used = x = the percentage of CO2 in the air examined.
A suitable alkaline solution may be prepared as fol-
lows : Dissolve exactly 4.766 grammes of pure sodium
carbonate (free from the water of crystallization) in one
litre of distilled water. Each c.c. of this solution is
equivalent to 1 c.c. CO2. For use : to 10 c.c. of this
solution add a few drops of neutral alcoholic solution of
phenol phthaleine and dilute to 100 c.c. Each- c.c. of
this dilute solution is equivalent then to 0.1 c.c. of CO2,
and used as above will give close results. The phenol
phthadeine is used as an indicator, as it loses its color as
soon as all the CO2 is absorbed and the alkalinity of the
soda solution is destroyed. The stock solution should be
kept in well-filled, tightly stoppered bottles. Example:
If 9 c.c. of the above dilute solution be used, and the
capacity of the bottle is 1200 c.c., then
9X0. 1X100 _ 90 . _ 00755
-1200=9- -1T9T-
the percentage of CO2 in the air of the room.
EXAMINATION OF AIR, WATER, AND FOOD. 343
Pettenkofer's Method. Into a large, clean bottle filled
as above with air of the room, 50 c.c. of a clear saturated
solution of lime-water (or barium hydrate) is introduced,
the bottle stoppered and then well shaken so that the air
may be thoroughly mixed with lime-water. The strength
of the lime-water, being unknown, is determined by means
of a solution of oxalic acid of such a strength that 1 c.c.
corresponds in alkalinity to 0.5 c.c. of CO2. (Such a
solution is made by dissolving exactly 2.84 grammes of
pure crystallized oxalic acid in one litre of distilled water.)
Into 25 c.c. of lime-water in a beaker, this acid solution
is run from a graduated burette until the alkalinity of the
lime-water is just destroyed, the neutral point being indi-
cated either by means of a few drops of phenol phthaleine
solution in the beaker, or by turmeric paper, the latter
being colored brown, and the phenol phthaleine retaining
its color as long as the solution is alkaline. When the
lime-water is exactly neutralized the exact amount of the
acid solution used is noted. Then, after the time necessary
to allow the complete absorption of the CO2 in the testing
bottle by the lime-water therein, viz., eight to ten hours,
25 c.c. of that lime-water is measured into a beaker and
the alkalinity determined exactly as above by means of
the oxalic-acid solution.
Now, inasmuch as part of the alkalinity of the lime-
water in the bottle has already been neutralized by the
carbonic acid in the air of the bottle, and as 1 c.c. of the
acid solution corresponds to 0.5 c.c. of CO2, it will re-
quire less of the acid solution to neutralize the lime-water
from the bottle than was required for the same quantity
of stock lime-water, and this difference expressed in c.c.
will express the number of c.c. of CO2 in the air of the
bottle or of the room from which it was taken.
344 A MANUAL OF HYGIENE AND SANITATION.
For, though each c.c. of acid solution is equivalent to
only 0.5 c.c. of CO2, the loss of alkalinity of only one-
half the lime-water introduced into the bottle has been
determined and the total loss of alkalinity would have to
be expressed by a difference of twice as many c.c. of acid
solution used multiplied by 0.5 c.c. CO2. The quantity
of carbonic acid in the bottle having been thus deter-
mined and the capacity of the bottle found by measuring
the quantity of water it will hold, the percentage of car-
bonic acid in the air is readily determined.
Example : 25 c.c. of stock lime-water requires 30 c.c.
acid solution; 25 c.c. of lime-water from bottle requires
27 c.c. acid solution.
Therefore, 30 ' c.c. — 27 c.c. = amount of carbonic
acid in the bottle, which contains (for example, say)
2550 c.c.
Then o= = °'12 per cent co° in the air
of room at current temperature and pressure.
Water.
To test for color, turbidity, etc., compare with distilled
water, using tall glass jars, and looking down through
equal depths upon a white surface. The smell of a water
may be detected by heating it to about 140° F. for a few
minutes in a glass-stoppered bottle. This test may or
may not indicate fecal contamination. Few polluting
impurities, when only in moderate quantities, give any
taste to water, and a dangerously polluted water may
have a good taste. Iron in small quantities, one-fourth
of a grain to a gallon, will give a taste to the water.
Use caution in tasting suspicious waters. Aeration is
EXAMINATION OF AIR, WATER, AND FOOD. 345
indicated by the lustre of the water and by the presence
of air bubbles on the sides and bottom of the vessel.
FIG. 62.
Bottle for collecting water at different levels.
Test for Chlorine. Solutions required. (I) Standard
nitrate of silver solution : to 1 litre of pure distilled water
add 4.788 grammes of pure silver nitrate; one c.c. of this
solution is equivalent to 1 m.g. of chlorine. (2) Potas-
sium chromate solution — a 5 or 10 per cent, solution of
346 A MANUAL OF HYGIENE AND SANITATION.
potassium chroraate made up in distilled water free from
chlorine.
Process. To 100 c.c. of the water add a few drops of
the potassium chromate solution, and then run in from a
burette or graduated pipette the silver solution, adding it
drop by drop and stirring the water with a glass rod.
Continue until a faint but permanent orange-red tint has
been produced, showing that all the chlorine has combined
with the silver, the persisting reddish color being due to
silver chromate. The number of c.c. of silver used indi-
cate the number of m.g. of Cl in 100 c.c., or parts per
100,000; this multiplied by 10 gives the number of m.g.
of Cl in one litre, or parts per million. If the water
contained but little chlorine, accuracy will be furthered
by evaporating 250 of the water to 50 c.c. over a water-
bath, and proceeding as above; the result multiplied by 4
will give the amount of chlorine in one litre.
Test for Nitrates. Solutions required. 1. Phenol-
sulphonic acid: 6 grammes of pure carbolic acid; 37 c.c.
strong sulphuric acid, and 3 c.c. distilled water. 2.
Standard potassium nitrate solution: Add 0. 722 grammes
of fused potassium nitrate to one litre of distilled water.
Each c.c. of this solution contains 0.1 m.g. of nitrogen
as nitrates. The water used in making the solution must
be free from nitrates.
Process. Evaporate 10 c.c. of the water to be exam-
ined (or 25 c.c. if it is presumably low in nitrates) just to
dryness, add 1 c.c. of phenol-sulphonic acid, stir with a
glass rod, and add 1 c.c. of distilled water and three drops
of H2SO4, warm, and add 25 c.c. distilled water and
NH4HO to excess and dilute with water to 50 c.c.
Treat 1 c.c. of the standard solution in an exactly sim-
ilar manner and compare the tints produced, diluting the
EXAMINATION OF AIR, WATER, AND FOOD. 347
darker until the tints match exactly, and calculating the
amount of nitrogen present by the amount of dilution
necessary — e. g., the tint from 1 c.c. of standard potassium
nitrate solution is darker and needs the addition of 50 c.c.
more water — i. e., up to 100 c.c. Therefore, 100 c.c. : 50
c.c. : : 0.1 m.g. N : x = 0.05 m.g. nitrogen as nitrates in
the 10 c.c. of water examined. The test depends on the
fact that the phenol-sulphonic acid is converted by the
nitrates into picric acid, which goes to form ammonium
picrate upon the addition of ammonia giving a yellow
tint to the water. The amount of picric acid and picrate
formed depends on the amount of nitrates present.
Test for Nitrites. Solutions required. 1. Sulphanilic
acid: dissolve 0.5 gramme of sulphanilic acid in 150 c.c.
of dilute acetic acid, sp. gr. 104. 2. Naphthylamine
acetate: boil 0.1 gramme of solid naphthylamine in 20
c.c. of distilled water, filter through a plug of washed
absorbent cotton, and mix the filtrate with 180 c.c. of
dilute acetic acid. 3. Standard sodium nitrite solution:
dissolve 0.275 gramme of pure silver nitrite in pure
water and add a dilute solution of pure sodium chloride
until a precipitate ceases to form, and dilute to 250 c.c.
with pure water. For use, dilute 10 c.c. of this solution
to 100 c.c. Each c.c. of the dilute solution contains 0.01
m.g. nitrogen as nitrites. Keep the solution in the dark
when not in use. All water in these solutions must be
free from nitrites; likewise all water used in tests, except
the sample under examination.
Process. To 25 c.c. of water to be examined, placed
in a cylindrical vessel, add 2 c.c. each of sulphanilic acid
and naphthylamine acetate solution, using a separate
pipette for each; in a similar cylindrical vessel dilute 1
c.c. of the standard sodium nitrite solution to 25 c.c. with
348 ^ MAX UAL OF HYGIENE AND SANITATION.
nitrogen-free distilled water, and add the same quantity of
the above reagents to it; compare the colors at the end of
five minutes and estimate the amount of nitrites by diluting
the darker tint until it matches the lighter; the result will
give the quantity of nitrogen as nitrites in the water, and
should not be over a trace. The above test is a very
delicate one.
Test for Hardness. Solutions required. 1. Soap solu-
tion: dissolve 10 grammes of castile soap in one litre of
weak (35 per cent.) alcohol. 2. Standard lime solution:
dissolve 1.11 grammes of calcium chloride in 1 litre of
distilled water; 1 c.c. of this solution is equivalent to 1
m.g. of calcium carbonate.
Process. Find out how much soap solution is needed
to make a lather with 100 c.c. of distilled water, as fol-
lows: Place the water in a flask holding about 250 c.c.,
and run in the soap solution from a burette, a few drops at
a time, corking and shaking the flask well after each addi-
tion ; the lather should have a depth of at least one-fourth
of an inch and be permanent for five minutes. Then
standardize the soap solution by diluting 5 c.c. of the stand-
ard lime solution to 100 c.c. with distilled water, and find
out how many c.c. of the soap solution are necessary to
make a permanent lather as above with it; this quantity,
less the number of c.c. needed to make a lather with 100
c.c. of distilled water, represents the amount of soap solu-
tion that will neutralize 5 m.g. CaCO3 or its equivalent;
lastly, determine in the same way the number of c.c. of
soap solution necessary to make a permanent lather with
100 c.c. of the water to be examined; subtract the quan-
tity necessary for 100 c.c. distilled water and estimate the
amount of CaCO3 or its equivalent present, as follows —
e. g., it takes 2 c.c. of soap solution to make a lather with
EXAMINATION OF AIR, WATER, AND FOOD. 349
the distilled water, and 12 c.c. with the diluted lime solu-
tion; then 12 c.c. — 2 c.c. = 10 c.c. = 5 m.g. CaCO3,
and each c.c. of the soap solution = 0.5 c.c. of the stand-
ard lime solution, or 0.5 m.g. CaCO3; consequently, if
100 c.c. of the water examined require 17 c.c. of soap
solution, it must contain (17 — 2) X 0.5 = 7.5 m.g., and 1
litre of water contains 75 m.g. of calcium carbonate or its
equivalent.
Tests for Lead, Copper, and Iron. To 50 or 100
c.c. of water in a white porcelain dish, or in a tall glass jar
over a white paper, add a few drops of ammonium sul-
phide; a dark coloration or precipitate indicates the pres-
ence of either lead, copper, or iron, due to the formation of
their respective sulphides. Then add a few drops of HC1 ; if
the color disappears Fe only is present; if it persists Pb or
Cu is present. In the latter case add a few drops of acetic
acid and about 1 c.c. of a strong solution of potassium
cyanide; if the color disappears it is due to Cu; if it per-
sists it is due to Pb. If Pb only is present the above test
will detect one-tenth of a grain per gallon. The above
tests may be corroborated as follows : Partly fill two test-
tubes with the original water; to one add a little potassium
chromate solution; an opacity and the deepening of the
color to canary yellow indicate lead. To the second add
a drop of HC1 and a few drops of potassium ferrocyanide
solution; a blue color indicates iron, either ferrous or ferric;
a bronze or mahogany-red color indicates copper.
Quantitative tests for the above metals may be made
by making standard solutions of the respective elements,
treating a measured quantity of the original water with
the proper reagent as indicated above, and comparing the
color produced with that given by a definite quantity of
the respective standard solution.
350 A MANUAL OF HYGIENE AND SANITATION.
Test for Phosphates. Solution required. Ammo-
nium molybdate: dissolve 10 grammes of molybdic anhy-
dride in 41.7 c.c. of NH4HO (sp. gr. 0.96) and pour
slowly into 125 c.c. of HNO3 (sp, gr. 1.20); allow to
stand in a warm place for several days until clear.
Process. Slightly acidulate 500 c.c. of water with
HNO3, evaporate to 50 c.c., and add a few drops of Fe2Cl6
and NH4HO to slight excess; filter, dissolve the precipi-
tate in the smallest possible quantity of HNO3 and evapo-
rate to 5 c.c. ; heat nearly to boiling, add 20 c.c. of
ammonium molybdate solution; keep the solution warm
for one-half hour. If there is an appreciable quantity of
precipitate, collect it on a small weighed filter-paper, wash
with distilled water, dry at 100° F., and weigh. The
weight of the precipitate multiplied by 0.05 gives the
amount of PO4 in the 500 c.c. of water.
Test for Free and Albuminoid Ammonia. Wank-
lyn's Method. Solutions required: 1. Standard ammo-
nium chloride solution: dissolve 0.382 gramme of pure-
dry NaCl in 100 c.c. ammonia-free water ; each c.c. of
the dilute solution contains 0.01 m.g. of nitrogen as
ammonia. 2. Alkaline potassium permanganate solution :
dissolve 200 grammes of KHO (in sticks) and 8 grammes
of potassium permanganate in 1 litre of distilled water,
evaporate to about 750 c.c. to drive off the ammonia
present and make up to 1 litre again with ammonia-free
water. To make ammonia-free water, add about 1
grain sodium carbonate to the litre of distilled water and
boil until about one-fourth is evaporated. 3. Nessler's
reagent: dissolve 15 grammes KI in 100 c.c. of distilled
water and 17 grammes HgCl2 in 300 c.c. of water; add
the HgCl2 solution to the KI until a permanent precipi-
tate is formed, then dilute with a 20 per cent, solution of
EXAMINATION OF AIR, WATER, AND FOOD. 351
NaHO to 1000 c.c., add HgCl2 solution till a permanent
precipitate again forms, and allow to stand until clear;
this reagent gives a brown or yellowish-brown coloration
if NH3 be present in water, and improves on keeping.
Process. Place 500 c.c. of the water to be examined
in a retort, connect with a condenser, and boil gently so
that the water may distil over slowly. The retort, and
condenser should have been thoroughly rinsed with am-
monia-free water. Collect the distillate, 50 c.c. at a time,
in Nessler tubes, add 2 c.c. of Nessler's reagent to each
50 c.c., and determine the amount of ammonia or nitrogen
in each as follows: Place in another Nessler tube 50 c.c.
ammonia-free water and 2 c.c. Nessler's reagent, run in
from a burette the standard ammonium chloride solution
until the color exactly matches that of the first 50 c.c. of
the distillate. Repeat the process with each 50 c.c. of
distillate until the test shows no more ammonia is coming
over from the retort. The total amount of ammonium
chloride solution used indicates the total amount of nitro-
gen of the free ammonia. Usually all the free ammonia
will come over in the first 150 or 200 c.c. of distillate.
Compare the colors by looking down through the tube on
a white surface. If the first 50 c.c. gives a precipitate
with the Nessler reagent it must be diluted and the
amount of nitrogen estimated from the diluted distillate.
The free ammonia being determined, allow the retort to
cool and add to the water remaining in it 50 c.c. of the
alkaline permanganate solution. This converts a certain
proportion of the nitrogenous organic matter into ammo-
nia; distil as before, estimating the amount of nitrogen
in each 50 c.c. of the distillate until no more ammonia
comes over. The amount of ammonium chloride solution
thus used will indicate the nitrogen of albuminoid ammo-
352 ^ MANUAL OF HYGIENE AND SANITATION.
nia, and the total amount of ammonium chloride solution
used in the whole process gives the nitrogen of the free
and albuminoid ammonia in one litre of water.
Pood.
Milk. Good Milk. Characteristics : Ivory white,
opaque, neutral or slightly alkaline reaction, no sediment,
no unusual or offensive taste or odor, sp. gr. 1029 or above;
cream, 10 to 40 per cent, by volume; fats 3 per cent, or
more; total solids, 12.5 per cent, or more.
Water is indicated by low specific gravity and by low
percentage of cream.
Skimming is indicated by a slightly raised specific
gravity (2°), by a low percentage of cream, and by a poor
color, though the deterioration in color may be disguised
by the addition of annatto, etc.
Watering and skimming are indicated by lowered specific
gravity, by low percentage of cream, and by poor color.
The specific gravity is determined by the lactometer, in
using which correction must be made for temperature, pro-
vided the latter varies much from 60° F., the standard.
The percentage of cream is determined by the cream
gauge or creamometer; the milk should be allowed to
stand in the creamometer for at least eight to ten hours,
and should be covered.
A very high percentage of cream tends to lower the
specific gravity theoretically; but when a milk is rich in
fat it is also rich in solids not fat.
An acid reaction, unless very slight, indicates souring
of the milk or the addition of some preserving acid. A
strongly alkaline reaction indicates the addition of some
substance like chalk, sodium carbonate, etc., to increase
EXAMINATION OF AIR, WATER, AND FOOD. 353
the specific gravity. Such addition is verified by an excess
of total solids, and by the effervescence of the latter — after
drying — upon the addition of a drop or two of HC1.
To determine the percentage of total solids: Weigh a
small evaporating dish, preferably platinum, add 5 or 10
c.c. of milk, and weigh dish and milk to get weight of
milk; evaporate to dryness over water-bath, completing
the drying in a water-oven until there is no further loss of
weight; weigh dish and contents (total solids); subtract
weight of dish, multiply by 100, and divide by weight
of milk. Result : the percentage of total solids.
To determine the percentage of ash: Ignite the total
solids over the naked flame until all black specks have
disappeared; cool and weigh; multiply weight of ash by 100,
and divide by weight of milk. Result : percentage of ash.
To determine the percentage of fats : Proceed as above
with 10 c.c. of milk, and evaporate until the residue is a
tenacious pulp, extinguish the flame, fill the dish half full
of ether, stir, and pound the residue thoroughly with a
glass rod, filter through a small filter-paper, reserving the
filtrate; add more ether to the residue, stir as before, and
filter, repeating the process three times or till the residue
is perfectly white; wash the filter-paper well with ether
and evaporate all the ether to dryness; weigh the residue
— the fat — multiply by 100 and divide by the weight of
milk. Result : percentage of fat.
Where a medical centrifuge is available for use, the
following method for the fat-determination will be found
to give results that are probably accurate to within one-
fifth of 1 per cent, of fat :
Two solutions are necessary: 1. Fusel oil, 37 c.c.; wood
or methyl alcohol, 13 c.c.; hydrochloric acid, 50 c.c. 2.
Sulphuric acid, sp. gr. 1.83.
23
354
MANUAL OF HYGIENE AND SANITATION.
Into the milk bottle, which is made to fit the centrifuge
and which has a long graduated neck, 5 c.c. of the milk
to be examined is introduced by means of a pipette, and
FIG. 63.
Bottle lor determining percentage of fat by means of the centrifuge.
to this 1 c.c. of the alcohol solution (1) is added and the
mixture well shaken by hand. The sulphuric acid is
then added, little by little, with frequent shaking, until
EXAMINATION OF AIR, WATER, AND FOOD. 355
the bottle is filled to the topmost (zero) graduation. It
is then rapidly whirled in the centrifuge until only the fat
occupies the neck as a clear layer, when the actual per-
centage can be read from the graduations. When the milk
is very rich — i. e., containing more than 5 per cent, of
fat — it will be necessary to dilute the milk with an equal
volume of water, and then to multiply the result by 2.
Likewise, cream should be diluted with four parts of
water and the result multiplied by 5. The same principle
is employed in the Babcock and other cream testers now
largely used by dairymen, etc.
Test for annatto: A percentage of cream considerably
lower than the color of the milk would indicate justifies
the suspicion that some coloring matter has been used.
This is frequently annatto.
Coagulate one ounce of milk with a few drops of acetic
acid and heat, strain, and press out excess of liquid from
curd; triturate the curd in a mortar or dish with ether, de-
cant ether and add to it 10 c.c. of a 1 per cent, solution of
caustic soda; shake, and allow to separate; pour off the upper
layer into a porcelain dish, put in two small disks or strips
of filter-paper; evaporate gently. Annatto will dye the
disks an orange or buff color. Moisten one disk with
dilute sodium carbonate to fix the color; touch the other
disk with a drop of stannous chloride. Annatto will
give a rich pink color. This test is sensitive to one part
of annatto in 1000 of milk, and with milk in any condition.
Test for boric acid : In igniting total solids boric acid
or boron gives greenish tinge to flame. Place in a porce-
lain dish 5 c.c. of milk, one drop of strong HC1 and two
of a saturated tincture of turmeric. Dry on a water-bath,
remove as soon as dry; cool, and add one drop of ammonia
on a glass rod. A slaty-blue color, changing to green, is
356 A MANUAL OF HYGIENE AND SANITATION.
given if borax is present. This test will show one one-
thousandth grain of borax. Less will give the green
color, but not the blue.
Butter and Oleomargarine. Good butter should have
good taste, odor, and color; it should not be rancid, and
should not contain too much water nor salt, nor should it
have any added coloring matter. The average composition
should be about as follows : Fat, 82 per cent. ; casein, 2
per cent, (not over 3 per cent. ) ; ash or salts, 2 per cent. ;
water 13 per cent. Butter fat is a compound of glycerin
with certain fatty acids, some of them volatile and soluble
in hot water, others non-volatile and insoluble in hot water.
Oleomargarine consists of ordinary animal or vegeta-
ble fats, melted, strained, cooled with ice, worked up with
milk, colored, and salted. These fats are usually beef or
mutton fat, lard, or cotton-seed, palm, or cocoanut oil.
If care and cleanliness are observed in the manufacture,
oleomargarine is not harmful nor innutritions, but it should
not be sold as butter.
Fraud is to be detected by observing the difference in
composition and properties of the fats. For instance :
BUTTER FAT. BEEP FAT, ETC.
1. The specific gravity is very rarely Beef fat, etc., is never above 904.5.
below 910, never below 909.8.
2. The soluble, volatile fatty acids Rarely more than % per cent. , never
average between 6 and 7 per cent., above yi per cent.
never below 4.5 per cent.
3. The insoluble fatty acids form Generally about 95 per cent,
about 88 per cent, of the total weight
of butter fat.
4. The melting point of the fat varies Rarely, if ever, above 82° F.
from 86° to 94° F. ; is usually from 88°
to 90° F.
5. Is readily and completely soluble Less so and leaves a residue,
in ether.
6. Under the microscope pure butter The contours of the small oil globules
fat consists of a collection of small oil are less distinct, and the larger ones are
globules, with an occasional large one. more numerous and irregular in size.
No crystals, except when the fat has Crystals of the non- volatile acids are
been melted. often seen.
EXAMINATION OF AIR, WATER, AND FOOD. 357
To determine the specific gravity : Melt a quantity of the
butter in a beaker in a water-bath at about 150° F. After
a time, when the fat is perfectly clear and transparent,
carefully decant the fat from the lower stratum of water,
curd, and salt into a fine filter; collect the filtrate and pour
into a specific-gravity bottle, which has been previously
weighed, both when empty and when filled with distilled
water at 100° F. See that the bottle is exactly full of the
fat, wipe clean, and weigh when the temperature is as near
100° F. as possible, because solidification soon begins
below this temperature. Subtract the weight of the
bottle, divide by the weight of the water which the bottle
contains, and multiply by 1000; the result is the specific
gravity.
To find the melting point : Pour a little melted fat into a
small test-tube (2" x J") and cool. Partly fill two beakers
of unequal size with cold water; place the test-tube in the
smaller (taking care to allow no water to mix with the
fat), and the smaller in the larger, and gently heat the
outer beaker. Suspend a thermometer in the smaller, near
the test-tube, and note the temperature when the fat begins
to melt; this is the melting point.
To determine the percentage of insoluble (non-volatile) fatty
acids: To 6 grammes of butter fat add 50 c.c. of alcohol
containing 2 grammes of caustic potash (KHO) and boil
gently for fifteen or twenty minutes to saponify the fat.
Dissolve the soaps thus formed in 150 to 200 c.c. of water,
and decompose with about 25 c.c. of dilute hydrochloric
acid. The separated fatty acids are poured upon a weighed
filter-paper, washed with two litres of boiling water, dried
at 95° to 98° C. and then weighed. The weight of these
insoluble fatty acids should not be over 90 per cent, of the
weight of the butter-fat.
358 A MANUAL OF HYGIENE AND SANITATION.
Flour and Bread. Wheat Flour. Characteristics:
Almost perfectly white, smooth, and free from grit; no
mouldy or unpleasant odor ; cohesive when lightly com-
pressed; no signs of parasites under the microscope; water
less than 18 per cent. ; ash less than 2 per cent, or more.
To determine the percentage of water and ash: In a
weighed platinum (or porcelain) dish place about 50
grammes of flour, weigh, and dry over a water-bath for
an hour or so; then complete the evaporation in a water-
oven until there is no further loss of weight; weigh, sub-
tract this weight, less the weight of the dish, from the
original weight of the flour. Multiply the remainder by
100 and divide by the original weight of the flour. The
result is the percentage of water. Then ignite the dried
flour in the dish and incinerate till there are no longer
any black particles and only the ash remains; cool, weigh,
subtract weight of dish, multiply the remainder by 100,
and divide by the original weight of the flour. The result
is the percentage of ash.
To determine the percentage of gluten : By means of a
glass rod, mix a weighed quantity of flour with a little
distilled water into a stiff dough; then repeatedly wash
away the starch and soluble constituents, kneading the
dough with the rod or fingers, and continuing until the
wash- water comes away clear ; the gluten and a small
amount of fat and salt remain. Spread out on a weighed
dish or crucible lid, dry in a water-oven, and weigh; mul-
tiply by 100 and divide by the original weight of the flour.
The result is the approximate percentage of gluten. The
gluten should pull out into long threads; otherwise, it is
poor.
An excess of water impairs the keeping quality and
lessens the amount of nutriment in the flour. An excess
EXAMINATION OF AIR, WATER, AND FOOD. 359
of ash indicates the addition of mineral substances. A
deficiency of gluten indicates that the flour is not pure
wheat flour. Parasites and fungi especially affect or live
in old or damp or inferior flour.
To test for mineral substances : Shake a little flour in a
test-tube with some chloroform, and allow it to stand for
a few moments. The flour floats and any mineral matter
sinks to the bottom, when it can be removed with a pipette
and examined under a microscope.
Wheat Bread. Characteristics : Fairly dry, light, and
spongy; clean and nearly white; of pleasant taste; not
sodden, acid, or musty; ash, not over 3 per cent. ; no para-
sites or mouldiness; no flour other than wheat; but little,
if any, alum; no copper sulphate.
Test for alum: Add 5 c.c. of a 5 per cent, tincture of
logwood and 5 c.c. of a 15 per cent, solution of ammo-
nium carbonate to 25 c.c. of water; soak a crumb of the
bread in this for a few minutes ; drain and gently dry.
Alum is indicated by a violet or lavender color; its absence
by a dirty-brown color on drying.
Test for copper sulphate : Draw a glass rod dipped in a
solution of potassium ferrocyanide across a cut slice of the
bread; copper is indicated by a streak of brownish-red
color.
Test for ergot in flour or bread : Add liquor potassae; a
distinct herring-like odor (due to propylamine) is appreci-
able if ergot be present.
An excess of water, an unnatural whiteness, and a low
percentage of ash in bread indicate the addition of rice.
Potatoes give an increased percentage of water and an
alkaline ash.1
1 For further details see Fox's " Examination of Food, Air, and Water," and
Kenwood's "Hygienic Laboratory."
INDEX.
ACCESSORY foods, 200
Air, 59
bacteria in, 64
currents, 102
diseases due to impurities in,
78
examination of, 339
filtration of, 95
-propeller, 107
-supply, source of, 95
Alcohol, 223
Alum, test for, 359
use of, in water, 153
Ammonia, "albuminoid," 177, 351
"free," 177, 351
test for, 350
Amylopsin, action of, 189
Anderson's process, 154
Anemometer, 100
Annatto, test for, 355
Antiseptics, 267
Antitoxin theory, 53
Antitoxins, 53
method of preparing, 55
statistics of use of, 58
Aqueous vapors, 62, 69
Argon, 61
Artesian wells, 139
Artificial ventilation, 95, 105
Ashes, 298
Aspiration, 97
Atavism, 233
Atmosphere, 59
composition of, 59
impurities in, 63
weight of, 59
Atmospheric contamination, extent
of, 90
index of, 90
BACILLI, 37
Backus heater, 113
Bacteria, classification of, 63
definition of, 32
differentiation of, 42
discovery of, 33
in air, 64
parasitic, 45
pathogenic, 46
saprophytic, 44
separation of, 38
Bacteriology, 32
Bacterium coli communis, 175
Bathing, 241
rules for, 242
sea-, 242
time of, 242
Baths, cold, 241
Russian, 244
Turkish, 244
warm, 243
Beans, nutritive value of, 217
Bedding, disinfection of, 281
Beef, 208
-tea, 221
recipe for, 214
Berkfeldt filter, the, 168
Beverages, 226
Bichloride of mercury, 273
Bile, action of the, 190
Boric acid, test for, 355
Bread, 215
wheat, 359
Broths, 213
Butter, 207
examination of, 356
Buttermilk, 204
CALCIUM hydrate, 274
Camps of detention, 296
of probation, 296
of refuge, 296
Carbohydrates, functions of, 194,
195
362
INDEX.
Carbohydrates, sources of, 194
Carbolic acid, 273
Carbon monoxide, poisoning by, 84
Carbonic acid, 61
effect of, 66
excretion of, 67, 237
poisoning by, 84
tests for, 341
Carpets, etc., disinfection of, 281
Census, the, 331
Cereals, the, 214
Cesspools, dangers of, 300
Characteristics, transmission of, 232
Cheese, 206
Chemical treatment of water, 152
Chloride of zinc, 274
Chlorides in water, 176
test for, 345
Chlorinated lime, 272
soda, 272
Chlorine, 274
fumigation with, 281
test for, 345
Cisterns, 131
Clark's process, 152
Closets, hopper, 315
pan, 313
plunger, 314
siphon, 315
valve, 313
wash out, 315
Clothing, 245
absorption of heat by, 249
advantages of woollen, 246
conveyance of infection by, 249
materials for, 245
purpose of, 245
sophistication of, 248
tests of materials for, 248
Coal gas, composition of, 85
poisoning by, 85
Coffee, 221
Cold baths, effect of, 241
Combustion products, 71
influence on health of, 83
Comparative mortality figure, 336
Convected heat, 109
Cooking, object of, 190, 211
thoroughness of, 211
Copper sulphate, 273
test for, 359
test for, 349
Corrosive sublimate, 273
Cotton, 247
Cowls, 97
Cramps," cause of, 242
Cubic space, 94
Culture media, 41
DEATH-RATES, 334
daily, 335
of cities, 22
standard, 336
zymotic, 335
Deep wells, 138
Deodorants, 267
Detention at port of entry, 286
camps of, 296
period of, in quarantine, 287,
293, 294
Devices for ventilation, 101
Dietetics, 183
Diffusion, 95
rate of, 96
Digestion, physiology of, 184
the gastric, 188
the intestinal, 189
the salivary, 187
Digestive ferments, 184
Direct-indirect radiation, 122
radiation, 122
Disease defined, 27
methods of study of, 327
Diseases affecting animals used for
food, 210
classification of, 28
due to impure air, 78
due to impure drinking-water,
142
due to respiratory vitiation, 82
hereditary, 233
transmissible by milk, 204
Disinfectants, chemical, 269
comparative table of, 279
thermal, 269
Disinfecting chamber, steam, 271
Disinfection, 29, 266
evidence of, 268
of infectious cases, 279
of rooms, 280
of water-closets, 319
thoroughness of, 268
Disinfector, duties of, 266
INDEX.
363
Domestic purification of water, 146
Drinking-water, infection by, 145
Duration of life, mean, 337
probable, 337
Duty of physicians, 24
EARTH-CLOSETS, 301
Economy in heating, 109
Eggs, 207
Enzymes, 184
action of, 186
characteristics of, 185
classes of, 186
Ergot, test for, 359
Estimation of radiating surface, 1 25
Examination of air, 339
of butter, 356
of flour, 358
of food, 352
of milk, 352
of water, 344
Exercise, 235
amount necessary, 240
effect upon brain development,
239
upon digestive organs, 239
upon heart action, 238
upon heat production, 238
upon respiration, 236
Exhaust system, 124
Expectation of life, 337
Extent of atmospheric contamina-
tion, 90
External ventilation, 88
FACTORS of ventilation, 90
Fans, 7
Farr, Dr. Wm., 20
Fatigue, cause of, 240
Fats, constructive property of, 197
digestibility of, 195, 198
functions of, 195, 196
melting point of, 357
properties of, 356
sources of, 195
todetermine specific gravity
of, 357
Filters, action of, 156
cleaning of, 163
construction of, 158
Filters, material for, 169
Filtration, 155
of air, 95
rate of, 163
regulation of, 158
Fire, disinfection by, 269
Fish, 209
Fixtures, location of house-, 306
trapping of, 306
Floor-space, 94
Flour, examination of, 358
test for minerals in, 359
Flush-tanks, 322
Food, 180
amount necessary, 191
classification of, 181
cooking of, 190
definition of, 180
examination of, 352
function of, 180, 181
Formaldehyde, 275
methods of using, 276
production from methyl alco-
hol, 278
regenerator for vaporizing so-
lutions of, 277
solutions of, 276
Formalin, 276
Formic aldehyde, 275
Formula for ventilating problems,
93
Free pratique, 294
Fresh-air supply, 91
Fruits, 218
Frying, 213
Fumigation, 281
Furnaces, hot-air, 117
Furs, 247
GARBAGE, disposal of, 298
Gas stoves, 112
Gaseous impurities, 65
Gastric digestion, 188
Germ theory, 33, 46
arguments for, 47
Germicides, 266
Gluten, to determine percentage
of, 358
Glycogen, 194
Grate fires, 110
Ground-water, 135
364
INDEX.
Ground- water, current of, 136
purification of, 135
HARD water, 132
diseases due to, 143
Hardness of water, 178
permanent, 132
temporary, 132
test for, 348
Health denned, 27
Heat, air movement due to, 98
convected, 109
disinfection by dry, 271
radiant, 108
transmission of, 121
Heredity, 230
Hippocrates, 19
Hospitals, purity of air in, 92
Hot air flues, 119
size of, 119
furnaces, 117
air supply of, 119
limitations of, 120
location of, 118
requirements of, 117
Hot-water heating, 121
House drainage, 303
-drain, 304
construction of, 305
niters, 164
classification of, 165
requisites of, 165
warming, 108
Humoral theory, 52
Hydrogen dioxide, 274
peroxide, 274
sulphide, 86
symptoms due to inhaling,
86
Hygiene denned, 17
personal, 228
reasons for study of, 24
school, 253
scope of, 17-19
ILLUMINATING gas, composition of,
85
poisoning by, 85
Immunity, theories of, 52
Impure air, diseases caused by, 78
Impure water, effects of, 142, 148
Impurities due to combustion, 71
due to respiration, 67
gaseous, 67
in air, 63
mortality due to, 80
Index of atmospheric contamina-
tion, 90
Indirect radiation, 122
Infection by drinking-water, 145
Influence of lighting agents, 73
Inland quarantine, 295
Inlets, location of, 103
Internal ventilation, 89
Intestinal digestion, 189
Involution forms of bacteria, 35
Iron, test for, 349
Irrigation, 325
KEFIR, 204
Koch's postulates, 49
Koumiss, 204
LABARRAQUE'S solution, 272
Lake water, 135
Lead in water, 144
test for, 349
Leather, 247
Life-table, factors of, 338
Light, 250
germicidal effect of, 251
influence upon health, 250
upon metabolism, 252
penetration of, 251
Lighting agents, influence of, 73
Lime, chloride of, 272
chlorinated, 272
milk of, 274
Limit of permissible respiratory
impurity, 91
Linen, 247
Liquid waste, disposal of, 302
Location of inlets, 103
of outlets, 102
Loomis-Manning filter, the, 170,
171
MARRIAGE, proper age for, 231
Mastication, value of, 190
INDEX.
365
Mean after-lifetime, 337
age at death, 337
Meat, composition of, 208
diseased, 210
Micrococci, 37
Milk, 201
as a carrier of disease, 204
care of, 202
examination of, 352
of lime, 274
sterilized cream, 203
Mines, atmosphere of, 78
Mortality, cause of infant, 335
due to impurities in air, 80
rate an index of water-purity,
149, 150
of infant, 335
rates, 334
Movement of heated air, 98
Mutton, 209
NATURAL ventilation, 95
Nitrates, 178
test for, 346
Nitrites, 178
test for, 347
Nitrogen, 61
OIL stoves, 114
Oleomargarine, 356
Open fireplaces, 110
Ophthalmia in schools, 264
Organic excretion, 70
matters in water, 178
Outlets, location of ventilation,
102
Overwork, effects of, 254
Oxygen, 60
absorption of, 237
PAIL-SYSTEM, the, 301
Paraform, 276
Parasites, 45
Pasteur filter, the, 168
Pathogenic bacteria, 46
Pepsin, action of, 187
Perflation, 97
Permissible respiratory impurity,
limit of, 91
Personal hygiene, 228
Petri dish, 39
Pettenkofer's method, 343
Phagocytosis, theory of, 52
Phosphates, test for, 350
Plenum system, 124
Plumbing for sewage, 303
Pneumatic system, 300
Poisson's formula, 329
Population, daily, 335
estimation of, 332
increment of, 331
weekly, 335
Pork, 209
Portable steam radiator, 113
Postulates of Koch, 49
Predisposing conditions, 29
Products of combustion, 71
Prophylaxis, 29
Propulsion system, 124
Proteids, functions of, 193
sources of, 193
Ptomaines, 45
Ptyalin, action of, 186
Pumping, effect of, 138
Purification of air by fire, 89
of ground-water, 135
of river-water, 133
of water, 147
by subsidence, 151
domestic, 164
Purity of air in hospitals, 92
QUARANTINE, 282
conditions requiring, 287
inland, 295
laws, purpose of, 283
origin of, 282
original meaning of, 282
railroad, 297
regulations at port of depart-
ure, 284
of entry, 287
during voyage, 286
school, 262
stations, location of, 289
requisites for, 290
treatment of cargoes in, 291,
293
of passengers in, 291, 293
of vessels in, 290
366
INDEX.
RADIANT heat, 108
Radiating surface, estimation of,
125
Eadiation, direct, 122
-indirect, 122
indirect, 122
Kailroad quarantine, 297
Eain-water, 130
cistern, 131
Registers, size of, 120
Removal of sewage, 298
Respiration impurities, effects of,
67
Respiratory vitiation, diseases due
to, 82
River-water, 133
purification of, 133
Roasting, 212
Rubber, 247
SALIVARY digestion, 187
Salts, function of, in digestion, 199
sources of, 199
Sanitary cordon, 295
science, 17
Sanitation, 17, 29
Saprophytes, 44
Schering^s lamps, 278
method of disinfection, 277
Schizomycetes, 32
Scholars, headache among, 256
prevention of infection of, 262
School furniture, arrangement of,
258
influence of, 257
-houses, care of, 261
construction of, 260
location of, 260
ventilation of, 260
warming of, 260
water-supply of, 261
hygiene, 253
infirmaries, 265
pathology, 254
quarantine, 262
-rooms, lighting of, 259
work, duration of, 254
Sea-bathing, 242
Sedimentation, 151
Septicaemia, 50
Sewage, chemical treatment of, 324
Sewage, composition of, 299
disposal of, 323
intermittent filtration of, 324,
325
-plumbing, 303
requirements of, 303
purification of, 324
removal of, 298
treatment by irrigation, 325
by sub-irrigation, 325
Sewer-gas, 75
bacteria in, 75
influence on health, 86
Sewers, 319
" combined," 319
construction of, 323
" separate," 321
shape of, 319
ventilation of, 320, 322
Shallow-wells, 136
Shoddy, 248
Sick-room, care of, 280
disinfection of, 286
Silk, 246
Smead system, 103
Soil, the, 76
-air, 75
circulation of, 77
influence on health, 86
-pipe, the, 303
location and construction
of, 304
-pipes, testing of, 310
ventilation of, 304
Solids, total, in water, 176
Soups and broths, 213
Source of air-supply, 95
Special diseases due to impurities
in air, 87
Spirilla, 37
Spores, 35
Statistical inquiry, principles of,
328
Steam, disinfection by, 270
-heating, 122
Steapsin, action of, 189
Sterilization, 39
fractional, 40
Sterilized milk, 203
Sterilizers, 40
Stimulants, cautions in use of, 224
classification of, 220
INDEX.
367
Stimulants, function of, 220
indications for use of, 224, 225
Stoves, 111
gas, 112
objections to, 112
oil, 114
Sub-irrigation, 325
Subsidence, 151
Subsoil-water, 135
Sulphate of copper, 273
Sulphur dioxide, 275
fumigation with, 281
Sulphuretted hydrogen, 86
Sulphurous acid gas, 86
Surface-water, 132
TEA, 221
Theory of antitoxins, 53
of Biichner, 52
of Chauveau, 52
of Metschnikoff, 52
of Pasteur, 52
Total solids in water, 176
Toxaemia, 50
Toxins, 45
Trap, bell-, 309
Bower's, 309
Cudell's, 309
inspection of, 310
McClellan's an ti- siphoning,
309
Traps, 307
S, or siphon, 307
seal of, 308
sink or pot, 308
siphoning of, 309
vent-pipes for, 309
Trillat's method of disinfection, 277
Trypsin, action of, 189
Typhoid fever, 150
Tyrotoxin, 204
VACCINATION of scholars, 264
Variety of food, necessity for, 183,
200
Vegetables, the, 217
Velocity of air-currents, 98
Ventilating grates, 111
problems, formula for, 93
Ventilation and heating, 88
Ventilation, artificial, 95, 105
devices for, 101
external, 88
factors of, 90
internal, 89
natural, 95
of sewers, 320, 322
of water-closets, 318
Ventilators, 97
Vital statistics, 327
numerical standard of,
328
variation in, 329
WASTE PIPES, 304
Water, 126
ammonia in, 177
bacteriological analysis, 175
bottle for collecting, 345
-carriage system, 302
chemical treatment of, 152
chlorine in, 176
classification of, 141, 179
-closets, disinfection of, 319
location of, 318
requisites for, 312
ventilation of, 318
diseases caused by impuritit
in, 142
double supply of, 128
effects of impure, 149
examination of, 173, 344
excretion of, 237
ground or subsoil, 135
hardness of, 132
lead in, 144
meters, 129
nitrates in, 178
nitrites in, 178
phosphates in, 178
-purity, index of, 149, 150
quantity of, necessary, 126
rain, 130
river, 133
sewage pollution of, 134
sources of, 1 29
storage of, 151
supply of cities, 127
surface, 132
the examination of, 173
the purification of, 147
368
INDEX.
Water, total solids in, 176
Wells, deep, 138
shallow, 136
Well-water, pollution of, 137, 140
Welsbach light, the, 74
/, Wheat, 214
Winds, 96 .
Wool, 245
ZINC chloride, 274
Zooglea, 37