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CORNELL UNIVERSITY.

THE
i ; Roswell P. Flower Libvary

- THE GIFT OF
a“ o ROSWELL P. FLOWER
FOR THE USE OF

THE N. Y. STATE VETERINARY COLLEGE
1897

  

 

 

 
‘ornell University Libra

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CATECHISM SERIES.

PUBLIC HEALTH

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420
P97
PREFACE.

T is hoped that the method of Question and Answer
here adopted will aid the Student in preparing

his work for Examinations—by suggesting possible
questions that otherwise might have escaped his
notice. In this way the book will be a great and
useful means of self-tuition. The small size of the
book, too, the absence of “packing,” will enable him
to run over the work the night before the Examination,

and recall the most important points to his memory.
PUBLIC HEALTH.

—_# Hee

WATER.

How much Water does the Body Require for Healthy Nutrition ?

Three and a half to five pints—70 to 100 ounces—in twenty-
four hours.

How much of this ts Derived through Food ?
About one-third—20 to 30 ounces.

How much Water is Required per Head in—
(a) “A Manufacturing Town ?”
Ans. 37 gallons.
(0) “A Non-Manufacturing Town ?”
Ans. 25 gallons.
(c) “A Rural Village ?”
Ans. 12 gallons.

What ts Peculiar about Rain Water in Manufacturing Towns ?

It is practically a very dilute solution of sulphuric acid, and
contains much suspended soot.

Name « Manufactory that Requires a very Large Supply of
Water ?
A gelatine manufactory; it uses as much as 10,000 persons
would.
6

For what Purposes is the Water Required ?

1. For domestic purposes, - - 12 gallons.
2. General baths, - - - : 4 on
3. For water-closets, - - - 6 on
4. Unavoidable waste, - 7 : 3 om

Total, 25 gallons.
This is per head in non-manufacturing towns.

Or take it thus—

1. Dietetic uses, - - - - 2 gallons.
2. Cleanliness, - - - - 16 on
2. For Sewers, - - - - 9 ou
4. Manufactories, - - - - 10 on

Total, 37 gallons.

What Amount is Allowed in the Army ?
15 gallons per head.

What Towns Require Little Water ?

Towns where the old-fashioned privies are used—“ privy
towns”—need much less than water-closet towns. In such towns
9 to 12 gallons per head will be enough.

‘Name some “ Privy” Towns ?
Norwich and Oxford.

Is this Apparent Waste of Water Real ?

No, It requires about this amount to pass from every house
in order to keep the sewers perfectly clean and clear.
How much Water would you Allow for Animals ?

For horses and cows, about 6 to 10 gallons,
For sheep and pigs, about } to 1 gallon,
‘

In Supplying a Town, what Amount of Water should be
aimed at?

50 gallons per head per day.

Give a Classification of Waters.
I. ‘Wholesome ” Waters—
(a) Spring.
(6) Deep well.
(c) Upland surface—z.e., uncultivated and unmanured
land, as hills and mountains,

IT. “Suspicious” Waters—

(a) Stored rain water.
(b) Surface water from cultivated land.

III. “ Dangerous” Waters—

(a) River water to which sewage gains access.
(b) Shallow wells.

Is “ Peaty” Water Bad ?

No; but it does not look nice, and is rather unpalatable.

What Happens to Sewage sent into Rivers?

It may be partially oxidised or otherwise rendered innocuous
by—
(a) The oxygen dissolved in the water.
(6) Green plants.
(c) Fishes.
(a) Deposition.
(e) Dilution.

Should the Sewage be sent into Rivers, therefore ?

Certainly not, and especially in the unpurified condition,
No river in this country is long enough to oxidise an appreciable
amount; and mere filtration will not remove the poison, though
it may clarify it.
8

Why are Shallow Wells so Dangerous ?

Because they are usually near old-fashioned privies, leaky

drains, and cesspools; and hence the sewage, etc., soaks into the
well, the water of which is thus apt to contain much “organic
matter.”

Is the Water Supply from Uncultivated Surfaces Good ?

Yes; it is probably the best means of supply, as we have
most command over it, The rain water is thrown off and stored
up before it is contaminated—e.g., Greenock, Edinburgh.

In Using the “ Suspicious” Waters, what should you Attend to?

To carefully collect, store and “filter.” Filtration will re-
move the impurities of rain water, together with leaves, excreta
of birds, vegetation.

What is Meant by ‘‘ Under Drainage” Water ?
It is water that has filtered through the soil, and is then

‘collected from drains 3 to 6 feet below the surface. Each acre
yields 30,000 to 70,000 gallons yearly.

Would this be a Good Supply ?

It often is; but, if it is from ‘‘manured arable land,” it is
not good, though even that is better than shallow wells. It is
best from uncultivated upland surfaces.

Will Filtering Purify the “ Dangerous” Waters ?

No; it will only clarify, but will not remove essential
poisonous matters.

How could you Render Shallow Wells less Hurtful ?

By puddling the walls with clay for 8 or 10 feet below the
surface, covering them in very closely, and using a metal pump
to abstract the water ; also remove all privies, dunghills, sewers,
etc, from their neighbourhood. Under these arrangements they
might do in a strait.
What ts a Shallow Well ?
One less than 50 feet in depth.

What are the Best Geological Formations to render the Water
Good and Sparkling as it Percolates through ?

In order :—
The chalk formations.
The oolite,
Greensand.
Hastings red.
New red conglomerate sandstone.

What is the Difference between an Ordinary Boring and an
“ Artesian Well” ?

An ordinary boring does not go through a retentive stratum ;
an Artesian well does—it taps the water imprisoned wnder the
stratum, which is thus under great pressure, and has probably
come from a great distance.

Name some Deep Artesian Wells.
Grenelle, in Paris, 1800 feet in depth.
Kissingen, in Bavaria, 1878 feet in depth.

The one at Grenelle drains a district or basin more than
100 miles distant from Paris.

Nume some Towns Supplied by “ Deep” Wells.

Canterbury, Cambridge, Bury-St-Edmunds, and Deal, have
deep wells coming from the chalk formations.

Birkenhead, Coventry, Leamington, and Southport, have deep
wells coming from the new red sandstone,

Bedford and Scarborough have deep wells coming from the
oolite,
10
Is Rain Water a Good Source of Supply ?

No; because—
1. The supply is uncertain.
2, The quantity falling in a given area is too small
for the inhabitants.
3. Expense of collecting.
4, Apt to become contaminated by storage.
5. It has a vapid taste.

What is the Average Rainfall in England ?

About 32 inches. In London and Edinburgh it is actually
about 24 inches.

- What Amount only can be Used ?

The quantity that runs off the soil of its own accord. As
a rule, one half or even seven-eighths is lost by evaporation or
sinking into the soil; so this would only leave about three
gallons for each person.

How much is an Inch of Rain per Square Yard ?
4°673 gallons.

How many Square Yards in One Acre ?

4840 square yards.

How much is an Inch of Rain per Acre?

3630 cubic feet, or 22,622 gallons; and this is equal to about
100 tons.

How would you Estimate the Rainfall as a Source of Water
Supply ?

Take the rainfall of the three consecutive driest years,
li
What happens to the Rain when it Falls?

1. Part is evaporated.
2. Part flows off the surface.
3. Part soaks into the soil.

How does the Rainfall affect the Temperature ?

One grain of water in being evaporated carries off sufficient
heat to raise 960 grains 1° F. This is because water, in being
converted into vapour, takes up and renders latent a great deal
of heat. When land is well drained, therefore, the country
becomes warmer, as there is less water to evaporate.

Name some Cities or Towns Supplied Wholly or Partly by
Rain Water.

It is almost the only supply of Venice and Constantinople,
and to a great extent supplies Gibraltar and Malta.

Name some Others ?

Many Dutch cities.

Why is this ?

Because they are, in many cases, below the level of the rivers
and sea, so that they cannot get rid of the sewage, which is
therefore apt to contaminate the water supply, from soakage
into the soil from cesspools, etc., and they have no springs fit to
drink, For these reasons they have to trust chiefly to collected
rain water.

Name two Diseases specially associated with Impure Water
Supply ?

Cholera and typhoid fever are intimately related to the water
supply. They have been shown by Pettenkofer to be specially
associated with the “ground”—or rather “ under-ground ”—
water.
12
In what Kind of Districts ts the Rainfall Greatest ?

It is greater in mountainous districts, and especially on the
leeward side of a mountain or the side facing the prevailing
winds—e.g., the hot vapour laden air from the Gulf stream
impinging on the Cumberland hills, causes a great rainfall in
some districts; so also the West Coast of Scotland is more
rainy than the East Coast. The effect of mountains is seen
near Ben Lomond, where the rainfall measures 91 inches.

What ts the Explanation ?

Air is able to hold more watery vapour in suspension the
higher its temperature; but the hot air impinging upon the
cold mountains is suddenly cooled, and therefore so much of
the vapour which it was, at its higher temperature, holding in
suspension is deposited as rain, as at the low temperature it
is unable to suspend it. Hence, on one side of a range of
mountains there may be fertile valleys, while on the other side
there is nothing but a desert—e.., the desert of Gobi is caused
by the Himalaya mountains,

How would you Estimate the Rainfall, say, on the Roof of a
House ?

Multiply the area by 144 to give the square inches, and this
again by the rainfall—this is now=cubic inches. To bring
this to gallons, multiply by 277:274 : or remember that a cubic
foot (= 1728 cubic inches) is = 62:5 lbs., and that a gallon is=
10 lbs.; therefore, a cubic foot is = 6: 25 gallons: also, 62°5 lbs.
is 1000 ounces, and this, therefore, is the weight of a cubic foot
of water.

Do you take the Slope of the Roof into account ?

No; just ascertain the jlat space covered by the roof, this
is = the joint areas of the ground-floor rooms, plus the thickness
of the walls and eaves,
13

How would you Judge of the Amount of a Well Supply ?

Empty it, and allow it to refill and note the time it requires,
and multiply by the size of the well. Regard the well as a
cylinder, and the cubic contents of a cylinder is = area of the
base x the height. Base is = a circle, and the area of a circle
is = twice the diameter x ‘7854.

How would you Estimate the Permanence of a Well ?

Ask the “oldest inhabitant ;” if no inhabitant, then judge
by the country: if there be a background of hills, then the
spring at its foot is probably permanent; if there is much CO,
in solution, is probably very permanent as it comes from a deep
reservoir in the limestone formations. One may also judge by its
temperature as to its depth, as deep wells are usually permanent,
especially of the new red sandstone and the chalk: the chalk
beds form one of the most extensive reservoirs known.

What Disadvantage is Present in Waters from the Chalk
Beds?

It is very hard; but the hardness is only “temporary,” and
it can be softened by Clark’s method (see after).

How much Chalk does it Hold in Solution ?
Every 1,000,000 gallons carry away 1} ton of chalk.

In Raising Water what is a “ Man Power”?
It is = 3300 foot Ibs.

What is a Horse Power? a Donkey Power? and One Horse
Power Engine ?
A horse power = 33,000 foot lbs.
A donkey power = 2 men.
1 horse power engine = 10 men.
Nors,—A gallon = 10 lbs,
14

What are the Characters of River Water ?

It is very like rain water, plus impurities from the soil, which,
of course, vary according to the kind of soil.

What is the Nature of Lake Water ?

It usually closely resembles river water, as lakes are usually
fed by rivers.

From whence ts Glasyow Supplied ?
From Loch Katrine.

Is this a Good Supply?

Yes; it is probably the purest natural water known. It only
contains about 24 grains of solid matters per gallon. This is too
little, and is probably its only drawback.

What are the Special Points about Underground Tanks ?

They must be water-tight, covered in and ventilated, and
deep rather than broad, to keep the water cool and prevent
evaporation, and they must be periodically and carefully cleaned
out. The walls may be of stone masonry, slate, etc.; common
mortar must not be used in their formation, as the lime is taken
up and the water becomes hard; use hydraulic mortar. If large,
must support the roof on piers or buttresses.

How do you Judge of its Capacity ?

A rectangular square of 16 x 10 will hold 1000 gallons for
every foot of depth. A circular one, with a diameter of 14}
feet will hold about the same amount. Divide the number of
gallons required by the whole population by 6-25, and multiply
by the number of days required, and this will give the size the
tank should be in cubic feet.

How many Days’ Supply would it probably be Required to
Contain ?

If the weather be dry, 120 days may be taken as the average,
15
Should Cisterns be Used ?

It may occasionally be necessary, but, at the best, they are
only necessary ev//s.

Of what Materials are they Usually Constructed ?

Usually lead; but zinc, slate slabs, and galvanised iron are
also used.

What is the Objection to Lead ?

Certain waters dissolve it to a considerable extent, and this
may cause lead poisoning.

What are the Speciul Points to be attended to in regard to
Cisterns ?

They should be well covered and protected from heat and
frost, should be easy of access and periodically inspected and
cleaned. They should not be in dark out-of-the-way corners,
and there should be a free circulation of pure air round them;
and they should themselves be ventilated. They should not
be near sleeping attics, or over water-closets, or near ventilating
pipes. No water for drinking or cooking should be obtained
from the same cisterns as that from which water is directly
drawn for the water-closets and sinks; and all water stored in
cisterns within the dwelling should be properly filtered after
it leaves the cistern. It is better to do without cisterns at all,
except for the water-closet and kitchen boiler. If there is a
cistern it must be so placed as not to damage the house should
it leak.

What are the Chief Points to be attended to in regard to the
“ Overflow Pipe” of a Cistern ?

It should never open into a sewer or water-closet pipe, because,
even though properly “trapped,” the “trap” might evaporate
16

and the gases pass up and be absorbed by the water. It must
have no communication with any other overflow or waste soil
pipe or drain. It should pass through an external wall and
discharge by an open end, some little way above the ground,
over a trapped grating; it should not, however, be near an
intercepting drain, trap or its grating, because, if the trap
evaporated, then gases are apt to be drawn up the pipe, by the
warmth of the house, to the cistern. A very safe and good
plan is to let the overflow pipe open into the roof gutters,
The end of the overflow pipe should be easily seen so as to
detect unnecessary waste. The overflow pipe should be used
only as a ‘warning pipe,” and open on the outer wall, so that
it can be readily seen. In this way it gives warning that some-
thing is wrong, as the cistern won’t overflow unless there be
something wrong with the valve of the inlet pipe. It may
also open into the bath or over a sink,

What is the Objection to its Opening on to the Outer Wall or
into the Roof Gutters?

It may become blocked up with ice in winter, and therefore
be useless, and the water thus overflow into the house.

Is it possible to take Water for the Water-Closet from the
General Cistern and yet keep it Pure ?

Yes; it might be possible, if the closet is fitted with a
“waste water preventer,” or if the pipe between the cistern
and the water-closet is always kept full of water—.e., THE
SUPPLY VALVE SHOULD BE ATTACHED TO THE WATER-CLOSET END
OF THE PIPE. In cases where the supply valve is at the cistern
end, it is impossible to keep the water pure, as the pipe between
the cistern and the basin, in the intervals of use, is full of gas
drawn up from the basin and closet, and the next time the
supply valve is opened, the gas bubbles up through the cistern
water, much of it of course being absorbed. The water-closet
should have a separate cistern for safety.
17

Should the Water-Closet Supply be taken Direct from the
Main?

No: water should never be taken direct from the mains for
water-closets, urinals, sinks, nor to hot water apparatus.

What are “ Waste Water Preventers ?”

They are forms of boxes holding a definite amount of water,
usually empting on the “syphon system.” With this apparatus
attached to a water-closet pipe we can only get a certain amount
every time the closet is used. This prevents the water being
turned on and left to run indefinitely.

How much Water does the Act of Parliament Allow for Each
Flush of the Closet ?

Two gallons for each flush; but this is too little to flush the
basin and clear out the traps well: and the further off the
water-closet is from the main sewer it requires still more.

What Special Points must be attended to in the Cleaning out
of Cisterns ?

The cistern must be frequently cleaned out, all chips of
mortar, etc., being very carefully removed, as they very speedily
corrode the lead or iron. It should always be cleaned out,
when, for example, the family returns from summer holidays,
and before drawing any water for cooking, drinking, etc., from
it. It should be cleaned out with a soft hearth brush, lightly
rubbed over it and with plenty of water; the sides must on no
account be scrubbed with a hard brush, or with sand or anything
rough, as this would remove the protective coating over the
lead, and expose the fresh bright lead surface to the action of
the fresh water, with the certainty that some would be absorbed
before another protective coating was deposited.

B
18
What ts the Chief Point in regurd to Domestic Filters ?

The material ought not to be “constantly” under water, but
ought to get time to be properly erated and oxygenised. It is
needless to say that a filter, however good at first, will not last
for ever.

1. It should be made of a proper material, which should not
colour the water nor add any impurity to it.

2. It must remove all suspended matters.

3. It should be easily cleaned or removed—say every three
months, as after three months’ use it is apt to contaminate the
water. /

4. The water should be allowed to pass through it very
slowly, so as to be in contact with the filtering material for
some time—at least one minute.

Give some Examples of Domestic Filters.

1. Purified animal charcoal.
2. Silicated carbon.

3. Spongy iron.

4. Carbide of iron.

5. An ordinary sponge.

What are the Objections to Charcoal ?

It is too expensive and soon loses its power.

How can it be re-Purified ?

By boiling with hydrochloric acid, to remove the earthy
salts.

What is Silicated Carbon ?

It is the residue left after the distillation of bituminous shale
—a coke mixed with mineral matters, two of carbon and one of
mineral matters,
19

What is “ Spongy Iron”?
It is prepared from hematite: the hematite is reduced with-

out fusion, at as low a temperature as possible. The water after
passing through this is apt to contain iron.

What is Carbide of Iron ?

It is a substance prepared by roasting a mixture of hematite
with saw-dust. -

In regard to the Placing of Water Pipes, what should be
attended to?
They should not be fixed on the outer face of an external
wall, nor yet even upon the internal face, especially walls facing
north or east, unless well cased and protected from frost.

What is the Best Protective ?

Probably a box filled with cocoa-nut fibre; sawdust decays,
and hair felt-rots.

In Cases where the Supply is Constant what should be between
the House Pipes and the Main ?
A good “screw down” tap should be placed at the entrance
of the pipe into the house, and this tap should be in charge of
the tenant.

Why?
So as to enable the tenant to turn the water off should the
pipes burst, and to empty them during frost.

Why do Householders usually state thut it is the Thaw that
Bursts the Pipes?

Because it is only when the thaw comes and the ice begins
to melt that the crack is discovered, as, of course, ice won’t flow
through a crack; but when the thaw comes, the ice plugging the
crack is displaced and water flows through.
20

Explain the Bursting of Pipes during Frost.

It is due to the fact that water, in freezing, eapands a little,
so that a cubic inch of ice occupies a greater bulk than a cubic
inch of water at the same temperature, and as the lead cannot
‘‘give” enough, of course it bursts.

Why are Lead Pipes su much used in Houses?
Because they are so handy for bends.

What is the Chief Objection?

Because the water acts on the lead, specially if the water be
highly oxygenated or contains much organic matter.

What follows from this?
That ‘‘shallow” wells are specially bad for lead pumps.

Mention another way in which a Lead Pump might be Dissolved
in Well Water.

Even in “hard” waters, the part of the pump -not actually
under cover of the water may be acted on thus: the water
evaporates from the surface of the well and fills the space
above with watery vapour, but this, in contact with the cold
lead, condenses as fine drops of pure water, and this pure water
dissolves a little of the lead and drips back into the well.

What Openings should there be in Pipes conducting Water to
Towns?

There should be “scouring valves” in valleys, so as to get
any sediment cleared out, and also taps at every half mile or so
to permit of repairs; also valve cocks at the summits of hills
and eminences, to let out air should it collect in the pipes.

Why is the Air Objectionable?

Because a comparatively small quantity will almost stop the
flow in pipes, unless the water is under great pressure; and
besides, it might be carried to the house pipes, where this is far
more likely to happen.
21
Give an Example of this?

The connecting pipe between two cisterns must “not be
bent upwards,” it must either be horizontal or bent downwards,
otherwise water won’t flow through unless under great pressure,
should there be a bubble of air in the pipe; the air, of course,
goes to the highest part and sticks there, and effectually prevents
the flow.

What about the Position of the Street Pipes?

In wide streets, or where there is much traftic, there should
be a service pipe at each side, to make the house pipes as short
as possible, and to be accessible without disturbing the traffic.
The water pipes, also, should be as far apart as possible from
sewers and gas pipes, as the risk of “ suction” from leaky mains
is very great, especially where the “intermittent system” is in
use.

What about the Depth of the Street Pipes?

It is a ditticult question ; if deeper than the gas pipes and
sewers, they are less likely to absorb “ gasses,” as gases of course
always tend to rise; but, on the other hand, liquid matters trom
the sewers percolate downwards, so that is a question of the
relative risks and likelihoods. If the sewers don’t leak, then
the water pipes should be placed below the level of the sewers
and gas pipes. ‘The sewers ought to be so constructed that they
will not leak; but, as the pipes are very often inferior—only
“seconds ”—and the work ‘‘scamped,” they very often do leak. |

Are Town Reservoirs Necessary ?

Very often they are, especially in certain districts, where
the demand for water varies at different hours of the day, and
THE GREATEST HOURLY DEMAND IS == DOUBLE THE AVERAGE
DEMAND. Lach reservoir should be large enough to contain at
least a day’s supply for the district in question, and should be
roofed in and ventilated.
22
What is meant by the “ Intermittent” and “ Constant” Supply ?

In the “intermittent,” the water from the reservoir is only
turned on certain days of the week, or at certain hours of the
day, and necessitates therefore a store in the house to last from
one to three days. In the “constant” system the water is
always turned on, and no store is required in the house except
for water-closets, sinks, and kitchen boilers.

What are the Objections to the ‘‘ Intermittent” System?

1. The chance of contamination is great.

2. There is often imperfect means of storage—e. g., often only
casks or tubs and often in the very worst possible positions, as
near privys, and overflow pipes into soil pipes, etc., so as to need
as short length of piping as possible. Besides, the mere fact
ot requiring a “store” is bad, and the means of storage is not
as a rule properly looked after, so that the water gets worse the
longer it is kept. Good water is spoiled and bad made worse
by the “intermittent” system. The necessity of supplying
cisterns also increases the expense; but the chief objection is
the great risk of rendering the stored water impure, as the
cistern is usually badly placed so that it cannot be cleaned, gases
are absorbed, dust and mice fall into the water, and it is usually
placed near a water-closet and the overflow pipe serves to allow
sewer gases to pass up to the water, which may thus become a
great means of spreading diphtheria and typhoid fever.

How may the Water be Contaminated in the Pipes by the
“ Intermittent” System ?

When the pipes and mains are empty of water, especially if
the joints be badly fitted or if there be holes in the pipes, foul
air is sucked in and fills the pipes and mains, and the next time
the water is turned on these gases are absorbed and carried to
the houses ; also if near leaky sewers, foul water may sipe into
the water pipes through leaky joints or holes, and be carried
into the cisterns the next time the water is turned on,
23
Could this happen with the “ Constant” System ?

Not if the water be under high pressure and not flowing
with too great velocity; but if the water flow rapidly past a hole
or leaky joint, foul gases, foul fluids, and debris might be sucked
in, or more properly forced in by the pressure of the surrounding
atmosphere, the rapid passage of the water along the pipe rare-
fying the air in the hole in question. The risk of this, however,
is far greater in the “intermittent” system.

What are the Disadvantages of the “‘ Constant” System—

(a) To Consumer 1
(0) To Water Company ?

The objections to this system are only removable failures,
there is no chance of contamination except in the pipes or
reservoir. The disadvantages are—

(a) To Consumer.—There are none if there be “ abundance”
of water, as at Glasgow; but if it has to be economised it is
often shut off, and the houses get none for hours, though this
is usually done at night. Again, sometimes a throttle valve,
ferrule, pin, or pea is put into the house pipe to reduce its
diameter, and then if the pressure be small the water only
“‘dribbles” into the house, and one must wait for a couple of
hours or so before enough water can be got for an ordinary
bath ; or, again, a water meter is put on and the water charged
accordingly, and this leads to sparing use and damage to health.
All these points, of course, are meant to save the Company’s
pocket, but tell against the consumer. It is best to have a
constant service at high pressure and direct from the main—
no cisterns, or storage tanks, or “ pea” in the throat of the
house pipe.

(0) To raz Company.—The “constant” system, it is said, is
apt to lead to great waste of water for bad fittings, fraudulent
abstraction of water, the fittings stolen and a great waste before
the theft is discovered. All this can be remedied by effective
control and proper appliances.
24
What are the Means to be adopted to Prevent Waste?

1. See that the fittings are good, with the best ‘screw 2
taps. ‘

2. Make the theft of fittings a specific offence punishable by
imprisonment.

3. Careful inspection by the Company’s Officers.

4, Allow no water pipe or waste, to open anywhere, where
the end of the pipe cannot be easily seen, so that waste could
be easily detected and prevented.

Name Towns Supplied by euch System.

Tue “ Constant ”—
Birmingham, Eastbourne, and Wigan.

Tue “ INTERMITTENT ”—
Bath, Oxford, and Tunbridge Wells.

What are the Causes of Waste in the ‘‘ Constant” System?

1. Escape between the main and the house ; this belongs to
the Water Company.

2. Careless consumption or wilful abuse. To check this the
Company’s Officers must supervise the taps and pipes, or waste
preventors may be introduced; the Company has also power
by Act of Parliament to enter houses and see that there is no
waste, and can also repair fittings at the expense of the tenant.

3. Waste from improper apparatus and fittings. All fittings
should be examined before they are fixed. In Manchester all
fittings are examined and stamped before they are sent out;
and in some places only authorised plumbers are allowed to
fix them up. If meters are used, do not charge for every drop,
like gas, because the people will not use enough and fall into
ill-health, sewers will become blocked, ete. Allow a certain

quantity each day, say 25 gallons per head, and only charge
above this amount.
25
What are the Usual Forms of Taps?

1. The plug tap, like the tap of a gas jet.
2. The screw down tap.

When may either the one or the other be Used ?

The plug tap shuts off the water by a single half turn, is
therefore rapid, and does very well in the intermittent supply
system, and also in pipes for cisterns as to sinks, etc. It is not
good in high pressure on the constant system, so for this, use
the screw down tap; the screw taps save the water pipes from
shock in the high pressure system: should a plug tap be used
in these cases, the sudden shock to the pipes is very great, as
the flow of water is checked so suddenly.

Which kind of Supply is best for the Poor?

The “constant” system, as there.are no cisterns to clean;
but it should deliver sufficient water at all times, and must be
distributed to every house and every flat of the house.

What should be the Size of the Water Pipes in the House?

In the “constant” supply pipes, half to one inch in diameter.

In the “intermittent,” one and a half to two inches.

What Strength should be Used ?

In Glasgow the weights used are—
4 inch diameter internally, 7 lbs. per lineal yard.

3 do. do. 10 do.
1 do. do. 14 do.
14 do. do. 18 do.

In London the weight is a little less.
26
How do you Calculate the Discharge from Pipes?

First find the velocity of discharge :—
Head x diameter of pipe
Length of pipe
All in feet. Take the square root and x result by 50,
and the result is = velocity in feet per second;

and
velocity x the area of the pipe, in feet, = the num-

ber of cubic feet discharged per second;
and
this x 6:25 = the number of gallons.

[Area of pipe = D? x‘7854.]

Give an Example of this.

Head, 32 feet.
Diameter of pipe, 4 foot.
Length of pipe, 100 feet.
32x4
“100
Square root of 16 = ‘4 and 44+50 = 20.
Velocity therefore is = 20 feet per second.
Let the sectional area be = one fifth of a foot.
Then 20x23 = 4
Discharge therefore = 4 cubic feet;
and

= 16

4x 6:25 = 25.
That is 25 gallons per second: this is in straight pipes.

What is the Eifect of Friction and Bends in Pipes?

The effect of “friction” is = “loss of head 3° the flow is
retarded and the water will not spout up to the same height
27

as the source; the effect of friction is greater the smaller the
pipe.
“Curves” retard the flow very much. In an angle of 40°
“loss of head” is = one-seventh of the original head.
An angle of 60° it is = one-third.
An angle of 90° it is almost = the original head.

In such cases the water won’t rise so high as the original
head, IF IT CAN GET OUT BEFORE; but still, if conducted in a
pipe, it will rise to the original height.

Does Water Dissolve Lead ?
Yes.

What are the Usual Sources of Contamination ?
Lead pipes and lead cisterns.

 

Whut Waters Act most on Lead?

Pure, soft waters, those highly oxygenated, and those con-
taining much organic matters, nitrites and nitrates,

Explain this.

At first the bright surface of the lead pipe is “ tarnished”
by the oxygen dissolved in the water, forming a thin film of the
oxide of lead; pure water will dissolve this to a certain extent,
or acids like nitrous and nitric unite with it, forming soluble
salts.

What Wuters act least on Lead?

Hard waters: those act least that contain much carbonic
acid, carbonates, phosphates and sulphates of lime, and mag-
nesium, and alkaline phosphates.

Explain this Fact.

The oxide may be formed at first as in soft waters, but the
acids present in hard waters, either free as carbonic, or combined
28

as phosphoric and sulphuric, form insoluble compounds with
the lead, and coat the interior of the pipe with a protective
and ‘riparneabile lining. Carbonic has great protective power,
though, if present in excess, may dissolve the compounds tormed
by producing soluble bi-carbonates. Lime salts are therefore
often spoken of as the “protective salts,” since they protect
from lead poisoning.

What is the Composition of the Protective Film Formed?

Carbonate and hydrate of lead with some phosphate and
sulphate; also some carbonates, phosphates, and sulphates of
lime and magnesia along with organic matters. It is this cover-
ing that must not be removed in clearing out the cistern.

Name other Conditions in which Lead is very apt to be Dissolved
in Water.

It is much more easily acted upon if galvanic action be set
up from the presence of dissimilar metals, as iron, zinc, or tin, as
lead pipes containing a certain proportion of zinc or vice versa,
or lead pipes lined with tin, and the tin cracking and allowing
the water to reach the lead. Bending lead pipes against the
grain is also bad.

What Amount is Required to Poison?

Any quantity over one-twentieth of a grain per gallon, as
a general rule, but apparently a less quantity has been known
to cause poisonous symptoms.

In a Household, who are Usually the First to be Affected by
Lead Poisoning, and why ?

The servants; because in the morning they draw aud use
the water that has been standing in the pipes all night, and for

this reason likely to contain a greater proportion of dissolved
lead.
29
How can Lead most Eusily be Detected ?

By means of sulphuretted hydrogen; the water is placed in
a tall glass jar, and then the observer looks down the jar against
a sheet of white paper.

What are the Characteristics of a Good Water Supply?

”

1. It must be of sufficient “ qnantity.
2. Of good general “ quality.”
3. It must be capable of due filtration.

4. It must be supplied at all hours of the day and night—
z.e., on the “constant” system.

What are the Characteristics of Pure and Wholesome Water?

1. It should be transparent, without suspended matters,
without smell or taste, well erated, and preferably without
colour—although peaty water is not necessarily other than quite
good.

2. The total solids should not exceed 8 grains per gallon,
of which only 1 should be dissipated by heat—unless it be in
“chalk water,” which may be allowed to contain 14 grains per
gallon of calcium carbonate, but only traces of the sulphate.

3. Matter destructible by heat should be under 1 grain, and
should scarcely blacken—allowance must be made for the de-
composition of calcium carbonate.

4, Reaction for nitrates, absent.

5. Reaction for nitrites and free ammonia, very slight.

6. “Albuminoid ammonia,” not more than ‘0056 grains per
gallon.

Water with a slight increase in the above quantities may
still be reckoned as “usable” though not pure water. It should
be sparkling from the presence of dissolved gases—carbonic acid
and atmospheric air. Small print should be read through a
depth of 2 feet.
——

30

What Substances ought specially to be Absent from Drinking
Water ?

Nitrites.

. Nitrates.

Ammonia and its salts.
Metallic salts.

Much organic matter.

. Alkaline sulphides.

. Sulphuretted hydrogen.

BY Se rie So et

What are the Characteristics of Rain Water?

It is almost as pure as distilled water—it is “natural” distilled
water, though it is apt to take up gaseous and suspended solid
matters in its passage through the air, as ammonia salts, nitrous
and nitric acids, and in some towns sulphurous and sulphuric
acids, and sulphuretted hydrogen; but the amount and kind of
materials thus taken up depends entirely on the state of the
atmosphere: its taste is vapid and unpleasant; it is very soft,
and therefore is much used for washing purposes, as it destroys
less soap and it is also good for making tea. It is highly erated,
thus—

Carbonic acid, , - - - 2.5 per cent.
Oxygen, - - - - 350 "
Nitrogen, = - - - - 62°5 "

It may take up lead or zinc from the surfaces on which it
falls.

Does it make a Good Water Supply?

It is good because of its purity and eration, but as a supply
it is bad as it is too uncertain, and large reservoirs are necessary,
and the water thus kept is apt to be contaminated.
31
Under what Conditions may it be Used with Advantage ?

1. Where the springs are bad from impregnation with earthy
salts, as in the ‘‘neutral ground” at Gibraltar, and in many
Dutch towns.

2. It may also be used with advantage during outbreaks of
cholera.

What are the Features of Ice and Snow Wuter?

In freezing, water becomes much purer, the salts and air
being almost all got rid of; when melted, therefore, ice water is
pretty pure, but heavy and non-erated. Snow water contains
the salts of rain water, with the exception of rather less ammonia;
the amounts of carbonic acid and air are very small: otherwise
it resembles rain water. The taste, however, is not pleasant.

Is Snow Water Unwholesome ?

Not of itself, but may be so by substances being thrown
upon it—e.g., as at Moscow, where the inhabitants had a
custom of throwing choleraic dejections on the snow round
their dwellings, and then melting it for domestic purposes:
in this way the spread of cholera was accounted for in 1832.
It is also said to cause gastric derangement.

What other Varieties of Water are there?

Suattow We.is.—These often contain much organic matters
(12 to 30 grains), and are not usually constant.

Deer WELLS anD Sprines.—In this case any organic matters
the water might at one time contain, are oxidised into harmless
mineral compounds: the water is also as a rule “hard,” as, in
its course though the soil and various deep strata, it becomes
impregnated with carbonic acid and takes up a good deal of salts
of very various kinds, especially lime salts. Artesian wells often
contain large quantities of the alkaline carbonates and sulphates
of lime.
32

River Water is softer than spring and well water, and
usually contains less mineral matter, but its composition is very
complex, and varies with season—-e.g., summer or winter: it
may also be contaminated with sewage, but as a rule river water
is fairly pure. Somé springs and wells contain much saline
ingredients that they are only used for medicinal purposes, and
are known as ‘mineral waters.”

Lake Water resembles river water, as lakes are fed by rivers,
but may contain much vegetable organic matters from their being
stagnant.

Marsa Warer always contains a large amount of vegetable
organic matters—12 to 40 grains or more: often much suspended
organic matters; salts are usually scanty—except the marsh be
near the sea—and consist of the carbonates, sulphates, and
chlorides of sodium, and calcium. It is always a suspicious and
impure water.

What is Distilled Water ?

It is water transformed into steam, or vaporised, by the
aid of artificial heat, and then condensed into water again by
the aid of cold: in short, it is vaporisation plus condensation.

Where is this Method frequently Adopted ?
At sea, as it affords an easy way of getting good water from

salt water, as the salts do not rise with the steam.

What is the Special Objection to the Water?

It is almost entirely free from air, and therefore very un-
palatable to some persons, and some say very indigestible.

How can this be Overcome ?

By allowing it to flow through a cask at some height, the |.

bottom being ee with fine holes to expose the water to
the air,
33

What other Precautions should be Taken?

To see that lead is not dissolved in the water, from the use
of lead pipes in the distilling apparatus or from zinc pipes
containing lead in their composition.

What is an “Impounding” Resérvoir ?

It is a reservoir formed by throwing a dam across a valley
through which a stream flows, and thus forming an artificial
lake—e.g., at the Moorfoot hills near Edinburgh.

Name a Disease said to be caused by Excess of Mineral Matters.

- Goitre ; due it is said to drinking water containing excess
of magnesian limestone or dolomite water (double carbonate
of calcium and magnesium). The action may also be helped
by iron impurity.

Where does this occur?
In Yorkshire, Derbyshire, and Switzerland.

What Methods are used to Purify Water?

1. Distillation.

2. Formation of a precipitate in the water, as in Clark’s
method.

3. Filtration.

Does Distillation completely Purify Water?
It gets rid of solid impurities, but not of carbonic acid,
ammonia, or other volatile bases.

What is Clark’s Method?

It is the addition of lime water to the water: the lime in
solution combines with the excess of carbonic acid that holds
the salts in solution, and throws down the carbonate as a fine
precipitate, and this, as it settles, also carries down suspended
matters. Hence, not only does this plan soften the water, but
it also frees it from suspended matters: it has no effect on the

sulphates and chlorides.
Cc
34
What Means are adopted to get rid of Organic Matters?

1. Exposure to aiy.

2. Boiling and agitation. -

3. Common alum.

4. Condy’s red fluid, and astringents, as ferric chloride and
the fruit of the strychnos potatorum.

| How does Alum Act?

This plan has been used for centuries in China and India to
purify from suspended matters. The carbonate of lime becomes
the sulphate, and this, with the aluminium hydrate produced,
entangles the organic matter and carries it to the bottom.

What is the Effect of Condy’s Red Fluid?

It removes bad smells and probably some organic matters
as well, by oxidation, as it readily gives up its oxygen: it may
also form a precipitate of manganic oxide, and thus carry down
organic matters. It may be used in foul smelling waters, by
adding a teaspoonful to 3 or 4 gallons and stirring constantly
till a permanent tint is left for five minutes; after this, filter
through animal charcoal.

What is the Usual Plan of Filtering Water ?

The water is first collected into large settling tanks, and
then filtered by ascent or descent, or both. The filters consist of
brick tanks open to the air, and at the lower part the filtering
layers are placed; the filter proper is usually from 3 to 5 feet
in depth. The upper two feet or so consists of sand; the lower
three, coarse gravel, becoming coarser and coarser as we pass
down. Sometimes there is a layer of bricks at the bottom.
The sand must be washed first with distilled water; white
sand is the best, and, if possible, it should be heated to redness
before use. The sand should be sharp and angular and not
too fine,
35
What Rate should the Water pass through the Filter?

From 70 to 75 gallons each square foot of surface in twenty-
four hours, or 700 gallons per square yard. Some do double
this amount.

How does a Filter like this Act?

The action is almost entirely mechanical. It acts by—
1. Straining. |
2. Removal of matters by adhesion to the sand.
3. Subsidence within the interstices of the filter itself.

It removes suspended matters, but only about 5 per cent.
of dissolved organic matters. As the action is mechanical
chiefly, it is therefore necessary to clean it occasionally, and
how often will depend on the nature of the water to be filtered.

How would you Clean it?

By removing half-an-inch or so of the sand on the top,
as this is the active part. The sand removed is then washed,
carefully cleaned, and may then be used over again,

What are the Best Domestic Filters?

1. Purified animal charcoal.
2. The magnetic carbide of iron or spongy iron,

3..A mixture of carbon, iron, and clay is also good.
(‘ Carferal.”)

How do such Filters Act?

Both mechanically and chemically, by oxidising the organic
matters; they remove both suspended and dissolved matters,
both animal and vegetable. The action, however, does not
go on indefinitely, and so they must be cleaned, but if the
amount of organic matter is small (under one or two grains
per gallon), the action is very permanent.
36
At what Rate should the Water pass through ?

Not too fast. The water should be in contact with the
filter for about four minutes.

How would you Prepare the Magnetic Carbide?
By heating red hematite with sawdust.

How is a Domestic Filter to be Cleaned ?

It may be taken to pieces every two or three months
(according to the kind of water), air blown through it, and,
if it is in a block form, well brushed; then pour a solution
of 20 or 30 grains of potassium permanganate to a quart of
‘distilled water with 10 drops of strong sulphuric acid through .
it. After this, a solution halfan-ounce of hydrochloric acid
to four gallons of distilled water; then rinse thoroughly with
plenty of distilled water, or good rain water. If the carbon is
not in the block form, it may be boiled with Condy, dried, and
reburned, and then used again.

What Diseases are said to be due to Impure Water ?

1. Diarrhea, from suspended or dissolved mineral, animal,
‘or vegetable matters; also from fetid gases, as sulphuretted
hydrogen.

2. Gastric disturbances, as dyspepsia, loss of appetite, where
the water is very hard.

3. Dysentery, from water rendered impure by sewage, sur-
face washings, etc.; coffee and red wine may help to prevent
. this as the tannin these fluids contain seems to act upon the
sewage: brandy is no use for this.

4, Ague and other malarious fevers, from marsh or ditch
‘water, due to the vegetable debris such water contains; so also
rivers draining dense forest land and rice fields,
37

5. Typhoid fever, cholera, and yellow fever can often be
traced to the use of impure water; probably the evacuations
gain access to the water, and there fermentation of the specific
virus occurs, which is then introduced by the water. This is
more likely to happen when the supply of water is intermittent,
or where the water-closets are supplied direct from the main ;
also, of course, in leaky mains and shallow wells in the neigh-
bourhood of privies, cesspools, cesspits, drains, and graveyards.

6. Gottre, from magnesian limestone waters, aiid some say also
from metallic sulphides, as iron and copper.

In what Forms may Nitrogen be found in Water ?

In any form, starting from fresh sewage matter, up to the
fully oxidised products, nitrates-+-as sewage matter, containing
nitrogenous organic matter when exposed to oxygen, especially
in the soil, undergoes a gradual oxidation.

Name the different Steps of this Oxidising Process ?
Starting with fresh sewage matters, we have :—

1. Organic matter, containing nitrogen; this is partially
oxidised, and we then get

2. *‘Albuminoid ammonia.” Still further oxidation gives
3. Fully or “ready formed ammonia,” The next step gives

4, Nitrous acid and nitrites ; and lastly, with full oxidation,
we have

5. Nitric acid and nitrates.

What 13 the Supposed Cause ?

Nitrification is believed to be due to the action of minute
micro-organisms.

Are Nitrates in themselves Harmful ?

No; they are perfectly harmless,
38
Why then is Water condemned when the Reaction for Nitrates
is well marked ?

Because although “nitrates” are harmless, yet their presence
points to their source, which is probably sewage matters finding
their way into the water. It is for this reason that the water
is condemned.

Would the Presence of Nitrates make you condemn every Water?

No; nitrates in water coming from deep chalk beds have no
such significance, as their source, the protoplasmic bodies that
once occupied the minute shells of which chalk is composed,
has all been completely oxidised long ago into the harmless
nitrates.

Whether would Nitrates or Albuminoid Ammonia in Water be
of more serious Significance ?

The “albuminoid ammonia,” as it is three or four steps
nearer the original source of contamination, and to this extent
imperfectly oxidised.

If Ammonia only is found in Water, what is its Significance ?

If ammonia alone be found in an otherwise clear and pure
water, without nitrites, nitrates, or chlorides, it is probably
derived from rain or “vegetable” organic matters ; but if, with
the ammonia, there be nitrites and chlorides in excess, it shows
that the water is polluted with animal organic matters, and is
not fit for use.

What is meant by the “ Hardness” of Water ?

Waters are called hard or soft according to the effect they
‘have on soap. When water lathers easily, it is said to be “ soft ;”
but when with difficulty, it is called “ hard.”
39
Explain this ?

A water only lathers freely when all the dissolved saline
constituents are decomposed, and this has first to be done by
the soap: the soap as it were, is first decomposed, the fatty acids
thus set free uniting with the bases in the water, forming oleates,
stearates, or palmates of lime and magnesia, and the alkali of
the soap uniting with the acids of these bases; then, after the

acids and bases are thus re-arranged, the water begins to lather
easily.

How is “ Hardness” divided ?
Into total hardness, consisting of :—

(a) Temporary hardness.
(0) Permanent hardness.

What is meant by “ Temporary” Hardness ?

The hardness that is got rid of by boiling the water, or by
Clark’s process.

What is it due to?

Usually the “carbonates” of lime and magnesia.

How does Boiling get Rid of this?

These salts are held in solution in the water by “excess of
carbonic acid.” Calcium carbonate itself, for example, is not
soluble in pure water. In boiling, the excess of carbonic acid
is driven off, the carbonates appear as precipitates, and when
the water is left at rest they subside.

What other Point does this Kaplain ?

The mode of formation of the fur or crust that forms in the
interior of boilers fed with hard waters,

1
40
What is Permanent Hardness, and what is it due to?

It is the hardness that is not got rid of by boiling, and it is
due to the presence of the “sulphates” of lime and magnesia,
chloride of calcium, etc.

ne

What ts meant by “ Degrees of Hardness

There are two meanings :—

1. Wanxtyn’s.—Here it means the number of parts or .
measures of a standard soap solution consumed by a gallon of.
water, in yielding a permanent lather, each measure—say a
cubic centimeter—representing one degree of hardness.

2. CuarK’s.—In this case it means the number of grains of
the carbonate or sulphate of lime, or its equivalent of other
soap-destroying salts, in a gallon of water; a degree of hardness,
therefore, corresponds to one grain of soap-destroying salts in a
gallon of water, and not as the last to the quantity of soap
whieh a gallon of water will destroy.

How much Soap does a Degree of Hardness destroy ?

About two and a half ounces of soap in each 100 gallons
of water, used for washing purposes, each grain of carbonate
of lime destroying ten grains of soap.

Name another Objection to Hard Waters.

It crusts boilers, and thus more fuel is wasted in heating
the water.

What would you call Soft, Hard, ete., Water ?

3 to 4 degrees of hardness is very soft.

8 to 10 degrees moderately hard.

20 + very hard.

At or below 6 may be called soft, above this hard,
41

What Proportion should exist between Temporary and Permanent
Hardness ?

If the total is 15 degrees, then of this about 10 or 12 should
be temporary, and the rest permanent.

Give a Classification of Waters according to “ Hardness.”

1, Rain water (softest).

. Upland surface.

. Surface water from cultivated land.
. Polluted river.

Spring.

. Deep well.

. Shallow well (the hardest).

NAO oF wl

What Process requires very Hard Water?

Brewing. In this case the water may contain as many as
28 or 30 degrees of ‘‘ permanent” hardness to the gallon—from
calcium sulphate—e.g., at Burton-on-Trent.

Why is this?
The hard water keeps out the colouring matter of the malt.

Why is River Water Hardest near its Source?

It is often very hard near the beginning, but as it flows on
the agitation caused by its flow over the stones gets rid of so
much of the carbonic acid, and a part, therefore, of the lime
salts is deposited on the stones, and thus the water becomes
softer.

What Domestic Plan is used to soften Water?

By putting a marble into the kettle; this, during the boiling,
rolls about agitating the water, and helps to drive off the
carbonic acid. It also lessens the deposit or “ fur.”
42
What Means could be adopted to Soften Water ?

1, Lime may be used.
2. Carbonate of soda may be used.
3. Soap may be used.

Give an idea of the Relative Amounts of euch required, and the
Expense entailed ?

1 cwt. of quick lime cost : . £0 0 8
43 ewts. of carbonate of soda cost 217 9
204 ewts. of soap cost . 3 “ . 47 1°58

So that 1 ewt. of lime will do as much as a ton of soap, and
of course at a very much less cost.

What are the Causes of Deposits in Steam Boilers ?

The driving off, by boiling, of the free carbonic acid, and
consequently the salts it held in solution are deposited.

2. The gradual concentration of the water, so that it is unable
to hold the salts any longer in solution.

What are the Disadvantages and Risks of these Deposits?

1. As the bottom of the boiler (next the fire) becomes
thickly coated, much more coal must be used to keep up the
steam ; hence this is wasteful, and entails more expense.

2. The boiler plates are allowed to become red hot, as the
water cannot reach the lower ones, and this leads to rapid
corrosion and wearing away of the plates and weakening of the
boiler.

3. The deposit or crust may crack, and allow the water
suddenly and directly to reach the red hot plates, and this is

followed by a very rapid generation of steam, and probably
bursts the boiler.
43
How are these Risks to be Prevented ?

1. Soften the water by Clark’s method before it is used to
feed the boiler.

2. Introduce some light matter into the boiler, to act mechani-
cally and keep the water in constant and violent motion, and
thus prevent deposits from taking place, and then blow out the
boiler frequently, thus getting rid of the granular debris.

3. Add ammonium chloride to the water: in this case a
decomposition takes place, the lime and magnesium salts become
transferred into the very soluble chlorides, while the carbonic
acid and free ammonia are driven off with the steam.

What is the Objection to this last Plan ?

The ammonia acts on the brass and copper fittings.

Deseribe Clark’s Process for Softening Water ?

The water is collected into large tanks and treated with as
much lime water as will neutralise the free carbonic acid present,
forming carbonate of calcium which is then precipitated with
the carbonate of lime previously dissolved in the water; this
gradually settles at the bottom, and in doing so carries down a
large amount,of the organic matter present. This plan may be
used. to soften water for paper mills or other manufactories ; and
also for town water supplies.

What are the Chief Objections to Clark’s Process ?

1. It requires large extra reservoirs when done on the large
scale, as large volumes of water have to be left at rest for many
hours ; this, of course, entails extra expense.

2. The great quantity of chalk that accumulates at the
bottom of the reservoirs, and that must be carted away occa-
sionally, also entailing extra expense.

3. The softened water is more likely to attack lead pipes.
4d,

EXAMINATION OF WATER.

How much is Required for a Complete Examination ?

From half a gallon to a gallon.

What Precautions have to be Observed in Collecting it?

The vessel must be very carefully cleaned ; an ordinary glass-
stoppered Winchester quart ( = about half a gallon) is usually
used. In a lake or pond, take the sample at some distance from’
the bank, and also at some distance below the surface, so as
to avoid scum and yet not disturb the mud at the bottom.
In towns, take it from mains or cab-stands. In a river, take it
from the centre, avoiding outlets of sewers or feeders.

What Gases are usually found in Water ?

Oxygen, nitrogen, and carbonic acid; sometimes marsh gas
(in marsh water), and sulphuretted hydrogen.

What Amounts are usually Present ?

Oxygen, about 32 per cent.; but the amount of this gas, as
well as of carbonic acid, depends on exposure to air, and on the
presence or absence of plants and animals and organic matters.

What Effect is likely to be produced by Organic Matters ?

The oxygen decreased, and the carbonic acid increased: the
amount of nitrogen is usually constant.

How are the Gases Estimated ?

By means of a mercurial trough, a graduated glass tube filled
' with mercury and inverted in the trough, a flask and connecting
tube. The water is put into the flask and gently boiled for
about an hour, and the gases are thus driven off and are collected
in the graduated glass tube,
45

Flow are the three Gases Separated ?

The “carbonic acid” is absorbed by caustic potash.
The “oxygen” by pyrogallate of potassium.
The “nitrogen” is read as the residue.

What are the Objections ?

1. Heat decomposes the carbonates,
2. It is impossible to get all the nitrogen and oxygen by this
method.

How is Sulphuretted Hydrogen Detected ?

1. By its smell = ‘rotten eggs.”

2. By a solution of the acetate of lead allowed to flow gently
over the surface of the water = “black streaks.”

3. By a solution of the nitro-prusside of sodium, having
first added a little caustic soda, as it only acts on sulphides =
“a violet purple colour.”

What is the Origin of this Gas in Water ?

From the de-oxidising influence of decaying organic matter
on the various sulphates present ; the sulphur and the hydrogen
unite to form the gas in question.

How do you detect Recent Sewage Contamination ?

By the “rapid” decolourisation of a solution of potassium
permanganate ; this would show the presence of much fresh
organic matters, most likely from sewage.

What are the Fallactes of this Test ?

Must first make sure of the absence of sulphuretted hydrogen,
ferrous salts and nitrites, as these substances would also very
quickly decolourise, the solution.
; 46
What is the Strength of the Solution ?

Two grains to ten and a half ounces of distilled water; ten
minims of this = one thousandth grain of oxygen.

What do you do before adding the Solution ?
Acidulate the water with a few drops of hydrochloric acid.

How long should the Colour remain if the Water be Pure ?

For at least five minutes; if gone before this time, more
must be added till the colour is pretty permanent: the amount
required and the rapidity of decolourisation will indicate the
nature and amount of the organic matters present.

What is the best Temperature for this Test ?
The whole process should be carried on at a temperature
of 140° F.
How do you Estimate the Total Residue or “Total Dissolved
Solids”?
By carefully evaporating a pint (20 ounces) of the water
to dryness, and then heat for some time at 150° C., until

the residue ceases to lose weight: this = the amount of the
“total dissolved solids.”

What is to be done neat ?

Heat the above to redness for a few seconds, and weigh
again.
What does this give you ?

The loss of weight is = the amount of “ volatile residue.”

Of what does it Consist ?

Destructible organic matters, nitrites, ammoniacal salts, and
sometimes chlorides.
47

What remains after the Volatile Residue is driven off?

The ‘saline residue,” consisting of the dissolved salts of lime,
magnesia, etc.

What Amount of Saline Residue should there be ?

Not less than 3 or 4 grains or more than 12 to 15 grains
per gallon.
It will be observed, therefore, that the “total dissolved
solids” consist of :—
(a) The volatile residue.
. (b) The saline residue.

In Heating the “Total Residue,” how do you roughly judge
of the Kind and Amount of Organic Matters ?

1. Smet. — A smell of ‘burnt feathers” indicates animal
organic matters. A smell of “burnt bread” indicates the
presence of vegetable organic matters.

2. Tue DrcrEE oF Coarrinc.—Organic matters always char
when heated :—
3 grains per gallon, causes some blacking.
6 " " causes a good deal.
10 " tt causes very marked blacking.

3. Detect nitrous acid (from the nitrites) by means of ozone
paper, or paper impregnated with iodide of potassium and
starch ;-this is moistened and held over the fumes arising from
the crucible.

How do you Estimate the Chlorine?

A measured volume of water is put into a white porcelain
basin, and to this is added a few grains of neutral potassium
chromate till the solution is slightly yellow. A graduated
solution of nitrate of silver is then dropped in from a burette
48

till a distinct and permanent red or brownish-red colour is pro-
duced. As 4 certain amount of the silver solution corresponds
to a given volume of chlorine, the extraction of the amount
present is a simple rule-of-three sum.

What is the Use of the Potassium Chromate?

It is to serve as an indicator, to show when the chlorine
has all combined with the nitrate of silver; the silver rather
combines with the chlorine present, but the moment that is
all used up it attacks the chromate, giving the distinct reddish-
brown colour of the chromate of silver.

How can you roughly judge of the Amount?
1 grain per gallon gives a haze.
4 noon gives marked turbidity.
10 ou " gives a well marked precipitate.

If there is much Chlorine present, what do you infer?
That it comes from:—
1. Strata containing chlorides of sodium or calcium.
2. Admixture with sea-water.
3. Liquid excreta of men and animals.

How do you Differentiate these Sources?

In the first two cases there is a great absence of oxidisible
or oxidised organic matters, although there is much chlorine
present. If from liquid excreta, there is also present ammonia,
nitrites, and nitrates, and probably also a good deal of oxidisable
‘organic matters, and probably also phosphoric acid.

Norz.—If nitrates markedly present and the water has
little action on Condy = “old or previous” sewage
contamination. But if there be nitrites, ammonia,
etc., and it has much action on Condy’s fluid, it
shows “‘recent” sewage contamination. So also if there
be much chlorine plus oxidisable organic matters, it
indicates recent sewage impregnation,
49
How are Nitrates Detected ?

1. By brucine solution and pure sulphuric acid. Pour the
acid down the side of the tube, so as to form a layer at the
bottom, under the mixed water and brucia solution. A pink
and yellow zone is found where the liquids meet, if nitric acid
or nitrates be present.

2. Concentrate the water, and add a mixture of sulphuric acid
and indigo; if nitrates be present, the blue colour disappears.

3. Concentrate the water—twenty ounces to about one
ounce — mix with an equal volume of ferrous sulphate, then
pour pure sulphuric acid carefully down the side of the tube,
so as to form a layer at the bottom. If nitric acid or nitrates
be present, a dark brown ring will be formed at the point of
junction of the two liquids.

4, Add sulphuric acid to the water, and then drop in a
solution of pyrogallic acid; this will give a pink and blue
colour, if nitrates be present.

If Nitrates alone are found in the Water what does it probably
indicate?

That it is due to the presence of nitrates of potassium or
sodium, or that it has come from animal substances of long
anterior date—e.g., the protoplasm of the foramenifera during
the formation of the chalk beds.

How ts Ammonia Detected ?

By Nessler’s solution (see after).

What is the Test for Nitrites?

Add a solution of iodide of potassium and starch to the
water, and then add sulphuric acid; if nitrites be present, this
should give an “immediate” blue colour.

What Precaution should be Taken?

Make sure that the iodide does not contain any iodate.
D
50
How are Sulphides Detected?

By nitro-prusside of sodium; this should give a violet
purple colour, —

Does this Distinguish between Sulphides and Sulphuretted
Hydrogen?

Yes, because it does not react with uncombined sulphuretted
hydrogen. A black colour with lead, but no colour with the
nitro-prusside, shows that the sulphuretted hydrogen is un-
combined.

What is the Test for Lime?

Oxalate of ammonium, which gives a white precipitate;
six grains per gallon gives a turbidity only.

How do you Detect Sulphuric Acid and Sulphates?
Chloride of barium and dilute hydrochloric acid give a white
precipitate. One and a half grains per gallon gives no pre-

cipitate till after standing. Three grains gives an immediate
haze.

How are Iron and Lead Detected ?

By means of sulphuretted hydrogen, giving a black pre-
cipitate or colour.

How are they Distinguished ?

Lead is only thrown down after the water has been acidulated,
say with sulphuric acid; whereas iron is only thrown in an
“alkaline” solution.

So H.S in an acid solution = lead.
H,S in an alkaline solution = iron.

What are the Conjfirmatory Tests for Iron ?

Red and yellow prussiates of potash; the red for the ferrous
salts, and yellow for the ferric: in each case a blue colour or
precipitate is produced,
| 51
How would you Estimate the Amount of Lead or Iron present ?

Leap.—Compare the colour produced by the natural water
with that produced in an equal amount of distilled water con-
taining a known amount of lead per gallon, when both are
treated with sulphuretted hydrogen.

Iron—Is estimated in the same way; compare the blue
colour produced in the natural water with that produced in pure
water containing a known amount of iron. Keep the tubes in
the dark for twelve hours or so, to prevent the blue precipitate
. from falling to the bottom.

How is the Saline or Ready-formed Ammonia Estimated ?

A pint of the water (20 ounces) to be examined are intro-
duced into a retort, connected with a Liebig’s condenser; into the
water put 10 to 20 grains of pure recently calcined carbonate
of soda, to make sure that the water is alkaline. The distilla-
tion is then commenced and carried on rapidly until about two
or three ounces have passed over; in this way any ready-formed
ammonia is carried over by the steam and is condensed in the
distillate, which is collected in a graduated tube and treated
with Nessler’s solution. If ammonia be present a yellowish or
brownish colour will be produced the depth of which depends
on the amount of ammonia present. The amount is estimated
by comparing the colour produced in pure water containing a
known amount of ammonia, with that produced in the natural
water, both being treated with Nessler’s solution.

How is the “ Albuminoid Ammonia” Estimated ?

When all the free ammonia has passed over, add to the water
about an ounce of a strong alkaline solution of potassium per-
manganate, and again carry on the distillation, and the amount
of ammonia estimated by Nessler’s solution as already described ;
the distillation is continued till the distillate is found practically
free from ammonia:
52

How is the “ Albuminoid Ammonia” expressed in the ubove
operation ?

In “terms of ammonia,” as the hot alkaline permanganate
transforms it into free or fully formed ammonia. It completes
the oxidation of the organic matters as far as free ammonia:
it is known as Wanklyn’s method.

Can the amount of Nitrogenous or Oxidisible Organic Matters
be expressed in any other way ?

Yes, in terms of “ oxygen required” to oxidise it.

How is this done ?

By means of potassium permanganate, in the presence of
sulphuric acid. A solution of a definite strength is made and
added to the water to be examined till no more of the solution
is decolourised, until the red tint is permanent for half-an-hour.

Does this Distinguish the different kinds of Organic Matter ?

No; recent sewage, ferrous salts, nitrites, and sulphuretted
hydrogen, all reduce and decolourise the permanganate solution
by removing its oxygen.

Name the two ways, then, in which the Permanganate may be
Used ?

1. In the presence of alkalies: here we get the amount of
organic matters in “ terms of ammonia.”

2, In the presence of sulphuric acid: in this case the amount
is expressed in terms of the “ oxygen required” to oxidise it.

If Ammonia alone be found in Water, what does tt indicate ?

It is nearly always present in small amount, probably from
rain; if there be much, and no nitrous or nitric acids or chlorine,
it probably comes from the decomposition of vegetable organic
matters—e.g.,in marsh water. If it exceeds ‘08 parts per mille,
53
it almost always comes from the fermentation of urea into am-
monium carbonate = dilute urine, very recent. In this case,

however, the water will be loaded with chlorides from the same
source.

What ts Nessler’s Solution ?

It consists of 108 grains of iodide of potassium dissolved
in a small quantity of distilled water: an aqueous solution of
mercuric chloride (corrosive sublimate) is added, until a slight
permanent precipitate is produced: now add 494 grains of
caustic potash, and make up the solution to 7 ounces with
pure distilled water. Mix, allow to settle, and draw off the
supernatant fluid for use as required.

What ts the Permanganate Solution ?

It consists of 882 grains of caustic potash, together with
35°27 grains of potassium permanganate in 10 ounces of distilled
water.

What Amount of Albuminoid Ammoniu is sufficient to Condemn

a Water ?
‘00 per mille = the purest.
02 to 05 " = very pure.
10 " = suspicious.
15 " = condemn.

What is Frankland and Armstrong’s Method fur Estimating
Nitrogen in Water ?

1. For the nitrogen present in the form of ammonia and
organic nitrogenous matter—first, destroy any nitrates or nitrites
present by means of sulpurous acid, and then evaporate a given
amount of the water to dryness: the total residue thus obtained
is then heated with oxide of copper in a combustion tube, and
the nitrogen and carbonic acid collected in a graduated tube.
The CO, is absorbed by caustic potash, leaving the nitrogen.
5A

9. For the nitrogen of the nitrites and nitrates, treat another
part of the water with strong sulphuric acid, and collect the
gases in a graduated tube near mercury; the nitrogen comes off
in the form of nitric oxide: the volume of this is then halved
for the amount of nitrogen.

What is Schultze’s Modified Method for the Determination
of Nitric and Nitrous Acids ?

By this method both are converted into ammonia by the
action of aluminium in an alkaline solution; the ammonia is
then distilled off, and the amount determined by Nessler’s
solution. ‘The reagents required are a solution of caustic soda
and sheet aluminium.

Name another Method for the same Purpose ?

The same object is attained by the ‘‘copper-zine couple”—
a piece of pure zinc foil and a 3 per cent. solution of sulphate
ot copper. The action is allowed to go on till a distinct coating
of copper is deposited on the zinc: the presence of oxalic acid
hastens the process. Afterwards distil off the ammonia, and
Nesslerise.

How is the Hardness of Water Ascertuined ?

By means of a solution of soap in proof spirit. It may be
done in two ways:—

1. Either by making the soap solution of a definite strength
by careful standardising, so that each measure (grain or cubic-
centimeter) is equal to a grain of soap-destroying salts per
gallon.

2. Or by making a water of a definite known hardness, by
means of pure distilled water and chloride of calcium, and then
seeing how much soap solution is required to neutralise the
hardness of a definite amount of the artificial water; then test
the hardness of the natural water, and compare the results;
55

Read thus:—If so many measures of the soap solution are
required to neutralise the hardness of a definite amount of
the artificial water containing a known amount of lime salts,
what is the hardness of the natural water that uses up, say
four times the amount of soap solution.

How is the Culcium Chloride Solution Made?

By dissolving a known quantity of pure white marble in
hydrochloric acid and evaporating to dryness, to get rid of the
acid, and then dissolving the residue in pure distilled water.

How is the Soap Solution Made?

Either by—

1. Dissolving a piece of soft potash soap of the B. P. in
equal parts of alcohol and water, and then filtering; or

2. Rub up so much of the lead plaster of the B. P. with
dry potassium carbonate, in the proportion of 150 to 40; lead
carbonate and potassium oleate (soft soap) are formed; dissolve
in rectified spirit, and filter.

How ts the “ Total Hardness” Estimated ?

A certain amount of the water under examination is intro-
duced into a wide-mouthed bottle, just as it is, and well agitated
to get rid of the carbonic acid, it being sucked out after each
agitation. The soap solution is then added from the burette,
with brisk agitation after each addition, until a lather is formed
which remains for at least five minutes over the “ whole surface ”
in an unbroken layer. The bottle is laid on its side. Let it lie
for half-an-hour and agitate again, and add a few more drops
of soap solution, if necessary; see that there is no break in the
lather, even after half-an-hour’s rest. Then read off the amount
of soap used up, and this = the degrees of hardness; only
deduct a little, as a certain amount of soap is required to
give a lather even in the purest water. This will then be the
“total hardness,”
56

How do you Estimate the * Permanent” and “ Temporary 2
Hardness ?

A known bulk of the water is boiled in a flask with a narrow
neck for an hour, care being taken to keep up the water to its
original bulk by the addition of distilled water; after the water
has thus been deprived of its carbonic acid, the hardness is again
estimated in the way just described; this result is then read as
the “ permanent hardness.” The difference between this result
and the one obtained by working with the natural water (total
hardness) gives the “temporary hardness”—that got rid of by
boiling. f

TaBLe oF Water ANALYSIS. .
Determine—
1. The total residue (total dissolved solids).
This consists of —
(a) Volatile residue.
(b) Saline or fix residue, consisting of—
(1) Chlorine.
(2) Earthy salts.
(3) Sulphuric acid.
(4) Sometimes iron and lead.
2. The products of organic matter—
(a) Ammonia (“ saline” or “ ready-formed”).
(6) Nitrous acid or nitrites.
(c) Nitric acid or nitrates.
3. The amount of oxidisible nitrogenous organic matter
(“albuminoid ammonia”).
(a) In “terms of ammonia.”
(b) In terms of “ oxygen required” to oxidise.
4, Hardness—

Pei (1) Temporary.

(2) Permanent.

 

BE, & 8, Livinasrone, Printers, 4 Melbourne Place, Edinburgh.
»

CATECHISM SERIE¢

 

 

PUBLIC HEALTH:

AIR AND VENTILATION.

EDINBURGH:
Ey & S: LIVINGSTONE,
1890.
THz 8e)

E. & §. LIVINGSTONE
4 MELBOURNE PLACE

EDINBURGH.
PREFACE.

T is hoped that the method of Question and Answer
here adopted will aid the Student in preparing

his work for Examinations — by suggesting possible
questions that atherwiae might have escaped his
notice. In this way the book will be a great and
useful means of self-tuition. The small size of the
book, too, the absence of “packing,” will enable him
to run over the work the night before the Examination,

and recall the most important points to his memory.
PUBLIC HEALTH.

 

AIR AND VENTILATION.

What is the Average Composition of the Atmosphere?
One hundred volumes of air contain—

Oxygen, - + = + 20°6 volumes.
Nitrogen, - - i - 77-9 me
Carbonic Acid, — - a 2 0-04 on
Watery Vapour, - x : 15 ’
Ammonia, - : 2 4

Ozone, - gi Be a a

Nitric Acid, - - = 5

Marsh Gas, - - -~ - Traces,
Sulphurous Acid, - -~— -

Sulphuretted Hydrogen, -

What are the Functions of the various Constituent Parts ?
“ Oxygen” is the supporter of animal life.
“ Nitrogen” serves to dilute the oxygen.
“Carbonic acid” and “ammonia” nourish plants.
“Ozone” is the great aerial scavenger.

Does the Amount of Oxygen vary ?
Slightly. It is about
20°96-"98 in pure mountain air.
20-90--87 in towns.
And least of all in low marshy places,

 
6,
What is the Amount of Watery Vapour ?
It varies from 1 to 12 grains per cubic foot.

Does the Amount of Carbonic Acid vary ?
A little: say from ‘02 per cent to 05. There is more in
sea air by day.

Give the Chief Constituents of Pure” and “ Very Pure” Air?
Purz Arr—

Oxygen, - - - - 20°96 per cent.
Nitrogen, - - - 79:00 "
Carbonic Acid,  - - - 00:04 "

Very Pure Arr—e.g., at seashore and heaths of Scotland—
Oxygen, - - - - 20°99 per cent.
Nitrogen, - - - - 78°98 on
Carbonic Acid, - - - 00:03 "

What is the Difference between the Weight and the Volume of

the Chief Gases ?
By Weight. By Measure.

Oxygen, 7 - - 77. = 79°19
Nitrogen, - - - 23... = 20°81

How does the Watery Vapour vary ?

It varies directly with the temperature: the lower the tempera- -
ture, the less can it hold in suspension, and vice versa. Usually
50 to 75 per cent. are Reels for complete saturation.

By iohat means are the Composition and the Purity oft the
Atmosphere maintained ?

' 1..By the great law of the ‘diffusion of gases.” Gases
tend to diffuse till the pressure of any given gas is the same at
every part of the globe.

2. Dilution by winds.
3. Oxidation by ozone, etc.
7

4, The fall of rain washes down the suspended matters and
absorbs the gases.

5. The green colouring matter of plants (Chlorophyll) in
the presence of sunlight and moisture decompose carbonic acid,
keeping the carbon, but giving off the oxygen. Plants also
absorb and decompose ammonia, and nitrogenous matters.

What is taken as the Measure of Impurity of the Air ?
The amount of “carbonic acid” present.

How can the Presence of this Gas be Detected ?

By means of passing the air through a solution of lime
water; the water soon becomes milky, from the formation of
the insoluble carbonate thus—

CaO + CO, = CaO, CO,.

‘

If Excess of the Gas be passed into the Water, what is the Result ?
The water becomes quite clear again.

“How is this?

It is due to the formation of the bicarbonate of calcium, which
is a soluble compound. It is usually said that the “excess” of
carbonic acid holds the lime salts in solution.

How could you Reproduce the Precipitate ?

By boiling the solution when the “excess” of carbonic acid
is driven off and the carbonate again precipitated.

What does this Explain ?
The “ temporary hardness” of water.

Is the Carbonic Acid the Real Impurity ?

No, by no means. It is the presence of nitrogenous organic
matters that constitute the real impurity, but the carbonic acid
forms an easily tested measure of the presence and amount of
these matters.
8

Name another and even better Test.

The nose of a person “just come in from the fresh and pure
outside air,” otherwise the sense is blunted and cannot be
depended on. Hence it is that persons “living” in a foul
atmosphere do not smell the disagreeable odour.

When does the Air become Dangerous and Disagreeable ?

It becomes “ very close and unpleasant” when the carbonic
acid reaches or passes 0°15 per cent., causing headache and rapid
deterioration of health.

Give Examples of the Evil Effects of Breathing Foul Air.

1. The “ Black Hole” of Calcutta.

2. The boat “Londonderry.”

In both these cases death was probably due to asphyxia
from the want of oxygen and excess of carbonic
acid, rather than to the organic effluvia.

3. Typhus fever, from re-breathing of fetid putrescent
matters; from overcrowding — “‘ochlesis”— as in jails (the
“Black Assize”), and camps.

4, Phthsis amongst soldiers.

5. Deaths from blood-poisoning, gangrene, and erysipelas,
in hospitals where the patients were overcrowded.

6. Glanders and farcy amongst horses.

7. Tuberculosis and phthsis amongst town cows.

How have these things been Improved?

By free ventilation and increased cubic space. Phthsis has
almost disappeared among soldiers; glanders and farcy among
cavalry horses; and diseases and deaths due to “ Hospitalism”
from hospitals.

What Gases Pollute the Air from Cesspools and Sewers?

Carbonic acid, carbonic oxide, nitrogen, sulphuretted hydrogen,
and ammonium sulphide. The oxygen is lessened and the
9

carbonic acid increased. ' It may also contain the special micro-
organisms of various diseases, as typhoid fever, cholera, autumnal
diarrhoea, diphtheria, putrid sore throat, and dysentery. Sewer
gases are often combustible.

Give an Example of this.

At Clapham, in 1829, twenty boys, out of twenty-two, were
affected from the opening of a drain at the school, though the
workmen escaped, probably because they were used to it or that
they did not form a suitable soil.

How is it that Typhoid Fever is more a Disease of the Rich
than of the very Poor?

The air carries the germs of the disease from badly trapped
drains, water - closets, etc., into houses, especially higher class
houses, because they are on a higher level usually, and the gas.
consequently tends to pass up to the highest point; and, besides,
these houses are more generally connected with the sewers,
through the medium of sinks and water-closets,-than are the
houses of the poorer people. Hence bad sanitary arrangements
are worse than none at all. It is specially bad when there is
a water-closet in the bedroom, as in many “high class” houses.

How is it that a heavy Fall of Rain will often stop Epidemics
of Cholera, Autumnal Diarrhea, etc.?

Because the fall of rain flushes out the sewers, washing away
the fermenting material, and also re-seals the traps.

What Changes does the Air undergo in Respiration?

1. It loses oxygen—about 4 or 5 percent.

2. It is heated some 13 or 14 degrees, only this varies with
the external temperature.

3. It obtains moisture—on an average about 10 ounces in
twenty-four hours.

4, It obtains carbonic acid in about 4 per cent. The air
loses a little more oxygen than it gains of carbonic acid, As
10

all the oxygen does not pass to combine with carbon, 1 per
cent. is apparently lost; hence, when an animal breathes in a
confined space, the Mincaheres is absolutely « diminished.

5. It obtains various organic impurities, as ammonia salts,
partially oxidised organic matters, etc.

How can these Organic Impurities be readily Detected ?

If one expires through ‘“ water,” the water very soon has a
bad smell; or if one breathe through a weak “solution of per-
manganate of potash,” the pink colour is destroyed; or through
“sulphuric acid,” when it darkens from the charring of the |
organic matters.

_ State—
» (a) The Amount of Oxygen Inhaled per Hour.
(0) The Amount of Carbonic Acid Exhaled. —

(a) 1346 cubic inches of carbonic acid are exhaled per ae
or ahout 636 grains, or ‘6 cubic feet.

(b) 1584 cubic inches of oxygen are inhaled per hour, or
about 542 grains.

In twenty-four hours about 26 ounces of oxygen are absorbed
and about 8 ounces of carbon exhaled, or nearly 28 ounces of -
‘ carbonic acid. 350 cubic feet of air pass through the lungs in
twenty-four hours.

What Gases Escape from—

(a) Alkali Works. |
(b) Chemical Works.
(c) Br ichfields,

(a) Hydrochloric acid gas, which destroys vesctalion round |
about the work.

(s) Ammonia, ammonium sulphide, and sulphuretted -
hydrogen.

(c) The air from brickfields is usually very peel and
‘contains much carbonic oxide.
11

| What Substance is often found in the Air of Printing Offices ?
It contains much antimony from the type metal—lead,
2 parts; tin, 1 part; and antimony, 1 part.
Nore then, in 24 hours—

10,000 grains of oxygen are consumed.
12,000 grains of carbonic acid are produced.
5,000 grains of water given off.

Compare the Carbonic Acid in Pure Atr and in Expired Air ?

In pure air, carbonic acid -04 per cent.
In expired air, - 4:70 "
or
Carbonic acid in 10,000 of pureair = 3 parts.
_ Carbonic acid in 10,000 of expired air = 470 n

Nore.—2000 persons will give off in two hours, 17 gallons
of water, and as much carbon as could be got from a hundred-
weight of coals.

What are the Natural Sources of Ozone ?

They are very numerous, oxidation of ‘metals, decomposition
of rocks, germination of seeds, growth of plants, falling of dew,
rain, hail, and snow, collision between air currents, passage of
lightning flashes, evaporation from saline fluids—e.g., the sea,
the dashing, splashing, smashing, and crashing of the restless
‘waves on rock-bound coasts. All these simultaneously develop
electricity and ozone. There is more ozone at high than at low
levels.

What are the Characteristics of “Ground Air?”

It is rich in carbonic acid, and very often is associated with
effluvia and organic gases, sometimes even sulphuretted hydro-
gen; clay soils especially give off much carbonic acid. Gases
from sewers may also escape into the soil, and these cause a
great increase in the amount of carbonic acid given off from the
surface. It is apt to give rise to malarious conditions.
12 sot
' Name an Example where this ts especially Bad and Dangerous ?
In houses built over newly “made soils” the “ground air”
is specially bad and dangerous for some time (say three years
at least), as the impure air from the miscellaneous collection ~
of rubbish on which the house stands is “drawn up” by the
warmth of the house—z.e., the warmth of the house acts as an
exhauster of the soil, and the atmospheric pressure outside then |
forces the air through the soil into the house.

What ts the Weight of a Cubic Foot of Air?

1 cubic foot weighs 536°6 grains; 100 cubic inches weighs
about 31 grains,

What are the Sources of Impurity in the Air?
1. Respiration of all living things.
2. Corrupt matters from disease.
3. Products of combustion in lighting and firing.
4, Solid particles and gases from trades and cooking foods.
5. Decay and putrefaction of vegetable and animal matters, %

Is a Candle a Safe Test as to the Presence of Carbonic Acid,
sufficient to Destroy Life—e.g., in a Mine or Old Well ?

It is safe enough in one way—that is, where a candle is ~
extinguished it would be death to venture; but a candle may
burn where a person would be choked. A candle will go out in
.25 per cent., but 5 per cent. will cause death.

How much Carbonic Oxide is Required to Produce Death ?
I per cent will cause rapid death, ‘5 per cent is poisonous,
and ‘1 per cent is injurious,

What is Water Gas?
It consists of nearly equal parts of carbonic oxide and |
hydrogen.

Why is it so Dangerous?
Partly from its apatite but chiefly because it has no
smell.
13

How might this be Prevented?
By adding some vapour to it which has a marked odour.

How much Ozone will Cause Death ?
When it reaches z}5th part of the atmosphere.

What is the Source of Sulphurous and Sulphuric Acid in the
Air of Towns? -

From the combustion of coals. For every 1000 tons of coal
consumed, 15 tons of sulphur are sent into the air in the form
-of sulphurous acid, and this is oxidised into sulphuric acid.
In Glasgow, alone, 300,000 tons of sulphur are thus sent into
the air, while London sends 75,000 tons.

What takes Place when Coal Gas is Burned ?

Carbonic acid, carbonic oxide, water, ammonia, and sulphur
compounds are produced. One cubic foot destroys the oxygen
from eight cubic feet of air, and produces two cubic feet of
carbonic acid, and two and a half grains of sulphuric acid. It
also raises the temperature of 31:29 cubic feet of air 100° F.

If the combustion is “imperfect,” then

, 67 per cent, of nitrogen is produced,
16 " water, and
5to6 n carbonic oxide.
Also sulphurous acid and ammonia.

What specially Favours the Production of CO?

‘When the gas is turned down low, so as just to leave a little
blue bead burning. This should never be done; either put it
out entirely or else leave it full on.

Compared with a Man, how much Air does an ordinary Gas
Burner Vitiate ?

A cubic foot of gas per hour destroys the atmosphere as
much as one man, and an ordinary burner will consume about
_ 8 cubic feet per hour; and each burner will therefore be equal
_ to three men, unless the products are removed by a special
‘channel, Hence the bad effects of gas-lighting.
14

How may this be Lessened ?
By the use of the electric light. This has lessened, in large

factories, the percentages of absences from illness considerably. “3

How is the Amount of Watery Vapour in the Air Estimated ?

 

There are many ways, but a convenient one is by means of

the wet and dry bulb apparatus.
What is the Principle of this Method ?

It consists of two thermometers, the bulb of one being E ms

covered with a piece of cambric, which is constantly kept moist
(the “ wet” bulb)—the bulb of the other one is not so covered
(the “dry” bulb). In dry air the amount of evaporation from
the ‘‘wet” bulb is great and rapid, and the temperature of that
thermometer consequently falls; but in dry air the amount of
evaporation is small, and therefore the fall of the temperature
is also small: the amount of watery vapour can therefore be
estimated by the difference between the readings of the two
thermometers.

Why does the Temperature Fall when the Water Evaporates ?

Because, when water is transformed into vapour or steam, | |

a large amount of heat is used up or rendered “latent,” and in
the present case this heat is extracted from the mercury in the
bulb covered by the moist cambric.

What should the Readings uf the Bulbs in a House be ?

Dry bulb should be from 63 to 65.
Wet bulb " 58 to 61.

The difference should not be less than 4° or more than 8°.
What is the Limit of Saturation ?

About 75 per cent. or less, or from 4:7 to 5 grains per cubic
foot, but this, as already stated, depends on the temperature,
thus—

at 60° F. it will require 5:8 grains for complete saturation.

At 50° F, it is saturated by 4:1 grains per cubic foot; while’ { -

d
7

 
15
How does the Carbonic Acid in a Room Differ from other
Impurities ? -
_ It diffuses equally through all parts of the room, whereas
the organic matters and watery vapour do not.

What Substances absorb the Organic Matters most ?

It is absorbed most by wool, feathers, damp walls, and'moist
paper; least by straw and horse-hair; as to colour, black absorbs
most, then blue, yellow, and white.

Give the Smell Test for these Organic Matters. :

It becomes perceptible when the carbonic acid reaches °07
per cent., and becomes extremely close and unpleasant when it
reaches ‘15 per cent.

Dr de Chaumont gives the following degrees :—

At ‘0568 per cent. Not close.

nu 0658 " Not very close.

u ‘0804 " Close.

n *0843 " Not very foul.

n *0921 mo! Pretty close.

un *0962 " Very close.

n +1090 " Extremely close.

n 1408 " Extremely close and unpleasant.

How can the Actual Amount of Organic Matter be Estimated ?

Draw a known quantity of the air slowly through pure
distilled water. The organic matters will be retained as free
ammonia, and as albuminoid ammonia, These substances are
then estimated as in water analysis. Distil to get rid of the
saline or ready-formed ammonia, and estimate its amount by
Nessler’s solution; then distil again, after adding a strongly
alkaline solution of permanganate of potash, when the albu-
minoid ammonia will be transformed into full-formed ammonia,
the amount of which is again estimated by Nessler’s solution.
It could also be estimated by drawing the air through a solution |
of known strength of permanganate of potash, containing free
sulphuric acid. In this case it is estimated by the amount of
“ oxygen required” to oxidise it.
+ © 16 .
Where do the Products of Firing and Lighting go respectively ?

Of firing, pass mostly into the atmosphere outside.
Of lighting, mostly into the air of the room.

Compare the Combustion of Dry Wood and Coal ?

1 b. of coal requires for its combustion 240 cubic feet of air,
and gives off many sulphur compounds.

1 bb. of dried wood only requires 120 cubic feet of air, and
gives off but very few sulphur compounds.

What is the great Difference between Complete and Incomplete

Combustion of Coal Gas ?

In incomplete combustion much “carbonic oxide” is pro-
duced.

What is the Poisonous Constituent of Coal Glas?

It is carbonic oxide, and when a person is killed by coal gas,
it is really a case of carbonic oxide poisoning. Sulphuretted
hydrogen, if present, is also poisonous; but in great quantity
this is an impurity and not a normal constituent of coal gas,
whereas carbonic oxide is a normal constituent.

How much Carbonic Oxide is there in Coal Gas?
About 4 to 5 per cent.

How much in the Fumes of Burning Charcoal ?
10 per cent.

How much Coal Gas is Required to Cause an Explosion?

10 per cent. in the air of ‘a room will cause an explosion
when a light is brought in.

What are the Luminous Gases in Coal Gas ?

Chiefly olefiant gas, and other hydro-carbons, having an
analogous composition—i.e, having double the number of
hydrogen atoms to the number of carbon atoms present.-
17

What ave the Non-Luminous Gases ?
Hydrogen, carbonic oxide, and marsh gas.

What are the Impurities of Coal Gas ?
Carbonic acid, sulphuretted hydrogen, and carbon disulphide.

What Amount of Sulphur is Allowable in Coal Gas?

The maximum quantity allowed is 20 grains of sulphur per
100 cubic feet of gas.

How are the Sulphur Compounds Detected ?

By means of paper soaked with a solution of acetate of lead.
When a jet of the gas is directed against this, if sulphuretted
hydrogen be present, the paper will be blackened.

What is the Objection to Sulphur Compounds in Coal Gas ?

In burning, it is given off as sulphurous acid, which is
very easily oxidised into sulphuric acid, and this spoils pictures,
hangings, furniture, ete.

How is it that the Atmosphere of Towns is. so Black and Foul ?

Because the suspended carbon and tarry matters of the smoke
do not rise higher than 600 feet, and therefore accumulate in the
lower strata of the atmosphere.

Should the Products of the Combustion are Coal Gas be Allowed
to Escape into Rooms?

No; they should be at once conducted to the outside by
proper ventilators over each burner. The retention of the
products cause great heat and humidity of the air of rooms.

Which Pollute the Air most—Coal Gas, Oil Lamps, or Candles ?

Coal gas gives off more carbonic acid than oil for an equal
amount of light, but less than petroleum. Candles spoil the
air more than gas—for an “‘ equal illuminating power”—but gas
gives off more watery vapour, and heats the air more, though it

does not produce more carbonic acid.
B
18

How can Carbonte Oxide be'Detected in Coal Gas ?
By means of a solution of cuprous chloride. This solution
becomes coloured black from the presence of carbonic oxide.

How does Carbonic Oxide Poison ? /
It is a light, very diffusible gas, and enters the blood very.
easily through the lungs, and combines with the hemoglobin of
the red blood corpuscles, forming a firm compound. It thus
displaces the oxygen, and prevents the corpuscles from carrying
any more; and from the firmness of the compound, it is almost
impossible to get rid of it in time to save the patient’s life,

What takes place when a Flame Impinges on a Cold Metallic
Surface?

(a) A “Luminous” Framz.—Soot is deposited on the cold
surface. This, by and by, may become heated to redness, car-
bonic acid produced; and then this, with the rest of the hot
carbon present, is reduced to carbonic oxide and is very apt to —
cause death.

(0) A “Non-Luminous” Fuams.—In this case there is no

soot or carbon deposited, and not the same risk, therefore, of

poisoning by carbonic oxide; but the hydro-carbons are imper-
fectly oxidised, and the products escape into the air of the room,
where they produce depression, and kill, like chloroform.

What Precautions, therefore, should be Taken?

If gas is used at all, don’t let it impinge directly on the
surface to be heated, and get a special flue to conduct the

' products of combustion to the outside at once—eg., in bath-

roonis,

What is the Peculiarity a the Blood in Cases of EanOnany by
this Gas? .
All the blood is of a “bright red” colour, both in the arterial
and the venous parts of the circulation, and the spectroscopic
appearances resemble those of arterial blood very closely,

 
19

How does Carbonic Acid cause Death ?

Mechanically. It is a very heavy gas, and diffuses very
slowly ; hence it fills up the air vesicles, and from the slow
diffusion oxygen cannot get down fast enough to support life.
In poisoning by this gas all the blood is of a very dark
venous colour.

What Diseases are Produced by Suspended Solid Matters in
the Air.

Respiratory affections, such as catarrhs, with or without
expectoration, bronchitis, emphysema, pneumonia, and chronic
simple phthsis.

Give Examples of these ?

Phthsis in stone-masons, millers, and miners; ‘miner's
" phthsis,” however, is not so common as seems to be generally
| supposed.

“Potter's asthma,” a form of emphysema, due to the fine
‘dust inhaled in this trade; so also in china scourers. In both
cases the dust is in an extremely fine state of division. ee
The steel-grinders are probably worst of all, as regards lung
affections. Pearl button-makers are also bad, and suffer from
bronchitis and hemoptysis; also pin-pointers, and electroplate
workers. . .

Cotton, flax, and shoddy factories are bad from the dust, and
suffer from bronchial affections.

Glass-makers, makers of grinding-stones, sand-paper, and
Portland cement, all suffer from dust.

Match-makers, from phosphorus poisoning and necrosis of
the lower jaw.

Makers of bichromate of potash suffer from ulceration and
destruction of the mucous membrane and cartilages of the nose,
though snuff-taking seems to prevent this; also from ulcers and
fistulous sores on the skin.

Brassfounders suffer from a form of ague, due either to the
20

fumes of zinc or copper—the metals forming brass. So also
coppersmiths and tinsmiths, from the fumes of the solder.

Painters and plumbers, from lead poisoning.

Silverers of mirrors and water-gilders suffer from mercurial
tremors.

Workers in arsenic, as makers of wall-papers, and artificial
flowers, and copper-smelters, suffer from arsenical poisoning.

How can these Bad Effects be, to a Certain Extent, Prevented ?

By proper ventilation, as in mines. In steel-grinding, use
the “wet” grinding if possible; have the wheel-boxes well
ventilated, and use respirators, either simply cloth, or a magnet.
In very dusty factories, have shafts, and ventilate by extraction.
In match-making, use the amorphous form of phosphorus, and
have plenty of the vapour of turpentine near the workers, For.

. painters, clean the hands carefully before eating, and use fitide
'' to drink containing sulphuric acid.

‘What are the Signs of “ Brassfounders’ Ague ?”

Lightness and oppression of the chest, nervous depression,
shivering, fever, an indistinct hot or a profuse sweating stage.

What are the Signs of Chronic Arsenical Poisoning ?

' Smarting of the gums, the eyes become inflamed and watery,
the eyelids edematous, eruptions on the skin like eczema, and a
silvery fur on the tongue. It may also go on to paralysis, more
’ or less general.

What are some of the Means of Purifying the Air ?

Free ventilation is the best purifier. Artificial means
may be—

1. Solid, as carbon, dried earth, and slaked lime.

2. Liquid, as solutions of lead nitrate, permanganate of
potash (Condy’s red fluid), and chloride of zinc (Sir W.
Burnett’s fiuid).

3. Gaseous, which are the most powerful, as ozone, chlorine,
bromine and iodine, sulphurous acid, nitrous acid, etc.
21

How does Carbon Act ?

Its action in the first instance depends purely on its physical
properties, due to the immense surface it presents for the absorp-
tion of gases, either from its porosity or from its fine state of
division. Afterwards, however, the absorbed gases are acted
upon chemically, being oxidised by the oxygen stored up in the
pores of the charcoal, as a cubic inch of charcoal absorbs nearly |
10 cubic inches of oxygen. The charcoal therefore acts (1) as
a deodorising agent, absorbing noxious gases; and (2) as an
oxidising agent, oxidising them into harmless products,

What Gases are most readily Absorbed ?

Ammoniacal gas and sulphuretted hydrogen—gases conspic-
uous among the offensive results of putrefaction. A cubic inch
of charcoal will absorb about 100 cubic inches of ammonia gas,
and 50 cubic inches of sulphuretted hydrogen. In the latter
case, the oxygen in the charcoal converts the hydrogen into
water, and the sulphur into sulphuric acid.

What kind of Charcoal is most Absorbent ?

Charcoal made from “ hard” woods, for in this case the pores
are finer and more numerous than in soft woods. Among the
best is logwood charcoal, and charcoal made from the shell of
the cocoa nut.

For what Purposes is Charcoal chiefly Used ?

To deodorise and, subsequently, oxidise sewer gases: the
ventilating openings in the streets are fitted with trays con-
taining charcoal in coarse powder. It is also used to absorb
organic emanations from disease; and for this purpose animal
charcoal and finely powdered peat charcoal are the best.

How does Charcoal lose its Power ?

By absorbing moisture into its pores chiefly, but also by
exhaustion of its oxidative powers.
22

How can it Regain its Powers ?

It regains its powers to a great dhe whan heated to iat
ness in a covered vessel.

How can Focal Matters be Deodorised ?

Probably best by means of dried earth, as in “ earth closets,”
and finely powdered earth in cases of artificial annus. Ferrous
sulphate is useful in treating the stools of typhoid fever.

How can Carbonic Acid be Absorbed ?

By means of exposing baskets containing unslaked lime in
the presence of the gas.

How can Sulphuretted Hydrogen best be got Rid of ?

By means of a solution of nitrate of lead, or of chloride of
zine (Burnett’s fluid).

For what Purpose was Chloride of Zine first Used ?

It was first employed by Sir William Burnett to. deodorise
and disinfect the bilge-water in ships.

What is Condy’s Red Fluid?
It isa strong solution of permanganate of potassium.

| For what Purpose is it Used ?

It is used to oxidise and destroy organic matters in sick-
rooms, on the hands, to decompose ammoniacal compounds and
absorb sulphuretted hydrogen ; it very readily gives up nascent
oxygen, especially in the presence of sulphuric acid.

flow is it Used ?

It is used exposed in flat dishes for the air of a room; in
tubs and basins, to receive the soiled linen and expectoration
of patients; also in the pot de chambre to receive the stools, and —
23

as an old sheet stretched across the doorway of the sick-room,
kept moist by sprinkling it with the dilute fluid. It may also
be used for water-closets, urinals, sinks, and drains, and is most
useful in removing the disagreeable odour of cats’ faeces below
beds, etc.

What ts Ozone ?

It is an allotropic modification of oxygen; it is sometimes
called condensed oxygen, as three volumes of oxygen condense
to form two volumes of ozone: it has a peculiar odour, and has
very powerful bleaching and disinfecting properties. It corrodes
india-rubber, and is completely soluble in oil of turpentine.

How can tt be Prepared Artificially ?

1. By passing a series of electric sparks through air or
oxygen; hence it is produced during the working of an electrical
machine,

2. By allowing a stick of phosphorus to oxidise slowly in
moist air.

3. By heating a platinum wire by a Bunsen cell.

4. By heating three parts of strong sulphuric acid with two
parts of permanganate of potash ; it will also be evolved slowly |
without the aid of heat.

How is its Presence Detected ?

By means of paper impregnated with starch and iodide of
potassium. The paper becomes blue in the presence of ozone,
as the iodine is set free and blues the starch: without the starch
paper would become brown not blue, and that method does very
well.

How can the Amount be Estimated ?

It can be roughly estimated by exposing a strip of prepared
paper for a given time, and then judging of the amount by the
depth of colour produced. In this way a scale of colour tests
may be formed,
24

‘How can Chlorine be Produced ?

1, From bleaching-powder by adding water, the carbonic
' acid of the air being sufficient to slowly displace the chlorine.
It is not, however, strictly speaking, “chlorine” that is given
off in this way, but ‘“‘hypochlorous acid;” the effect, however,
is the same, :

2. From four parts of hydrochloric acid, and one part of the
black oxide of manganese (“ pyrolusite”).

3. From four parts of common salt, two parts of sulphuric
acid, and one of the black oxide of manganese, with a little
water.

4. By mixing a solution of permanganate of potassium
with hydrochloric acid.

How does Chlorine Act ?

It only acts in “the presence of water or moisture,” but
when this is present it is a true oxidiser, the chlorine taking
the hydrogen and forming hydrochloric acid, while the oxygen
of the water in the nascent state, can then oxidise oxidisable
matters. In this way it decomposes sulphuretted hydrogen,
forming water and sulphuric acid, and also in a similar manner
decomposes ammonium sulphide,

What is Huchlorine ?

It appears to be a compound of anhydrous chloric and
chlorous acids, mixed with free chlorine.

How is it Produced ?

By the action of strong hydrochloric acid upon chlorate of
potash; place the two substances in a.saucer, containing warm
water, and the gas is slowly evolved.

How does it Act 2.

Just like chlorine, but is less irritating to the lungs, and the
odour is more pleasant, so that it can be tolerated readily enough
in a sick-room,
25

What Precautions are Necessary ?

It is a heavy gas, and therefore must not be placed on the

_ floor, but on a shelf high up, so that it will, fall slowly down:

of course, being an explosive gas, it must not be produced in
too large a quantity.

Can Iodine be Used ?

Yes; just expose the scales in a perforated box to the
air, or heat them gently: it acts like chlorine, but is not
so diffusible, and condenses easily.

Is Bromine Used ?

It might be, but it is far too irritating to the lungs, not to
speak of its very bad smell, All that is necessary is to expose
the fluid in a saucer.

How is Nitrous Acid Produced ?

From copper and nitric acid. The first result is nitric oxide,
but this very readily takes up oxygen from the air, and forms
nitrous acid. It is a very powerful oxidiser of organic matters,
and, like’ chlorine, “transfers” the oxygen of the air to the
organic matters in the nascent condition. It removes the bad
smell from the dead-house sooner than anything else. It is
very irritating to the lungs, however, and must therefore be
evolved slowly.

How is Sulphurous Acid Produced ?

1, The easiest way is to burn sulphur in the air.

2, By the action of sulphuric acid on certain metals, as lead
and copper.

3. By the reducing action of carbon, or substances containing
it, as wood, upon sulphuric acid.

How does tt Act ?

It only acts in the presence of moisture or water, and then —

ina way the very reverse of chlorine, as the sulphurous acid
takes the oxygen of the water, and gives up the hydrogen in
26 -~
the nascent condition. It is not therefore a true oxidiser,

though it decomposes sulphides, as sulphuretted hydrogen,
forming water and free sulphur.

How does it Extinguish a Chimney on Fire ?

In the same way: the sulphur is burned to form sulphurous
acid; this in the presence of moisture—say from a wet sheet in
front of the fire—removes the oxygen and sets the hydrogen ©
free; but hydrogen is not a supporter of combustion, and so
the fire is extinguished for want of oxygen.

‘What is the Popular Chimney Extinguisher ?
Common salt thrown on the fire.

Is this Good?

- No; the very reverse, as the fire is fed not extinguished,
since the chlorine set free takes up hydrogen and gives off the
oxygen, and so the fire is increased though “the smoke is
lessened,” and this is probably the reason of the popular belief
in common salt as a fire extinguisher.

Name some other Popular Disinfectants ?

Carbolic acid, camphor, and vinegar. The action of vinegar
is doubtful, but it does no harm and may do some good.

. What do you mean by Ventilation ?

It is the removal by a stream of air, without perceptible
draught, of the pulmonary and cutaneous exhalations of men,
products of combustion of lights, effluvia from persons and
discharges, etc.

What Points have to be attended to?

1. The amount of air required.

2. The original cubic space.

3. The direction of the ventilating currents.

4, The rate of movement of the currents, as there ought to
‘be no perceptible draught, even to the most sensitive.
27
In what Special Ways is the Air Vitiated?

_ 1, By increase of “temperature” up to 5° F. or so above the
general temperature, it feels fresh and comfortable; but when
it reaches 12° or 13° F. above this, it feels very close.

2. By increase of “ moisture.” When the moisture is three-
tenths only, all is well, but when it reaches 1 or 1} it is:
unpleasant. A very fair and healthy amount of moisture and
heat is shown when the dry bulb stands at 60° F., and the
moist bulb at 4° less—z.e,, 55° F.

3. By increase of organic matters and carbonic acid.

How are the Evil Effects Obviated ?
1. By diminishing overcrowding.
2. Supplying plenty of fresh air.

What are the Army Regulations as to Space?

In permanent barracks, - 600 cubic feet per head.
In wooden huts, = - - 400 " "
In hospitals at home, - 1200 " "

In hospitals in the tropics, 1500 " "
In wooden hospitals at home, 600 " "

What Space do Lodging-Houses Give?

As little as they can. The Metropolitan lodging-houses give
240 cubicfeet per head! The Dublin registered lodging-houses,
300 cubic feet. The Edinburgh lodging-houses, 400 cubic feet
as the minimum. ~

Is mere Cubic Space Enough?
Cubic space “alone” is not enough. The chief thing is to
secure proper renewal of the air.

What is the Limit of Maximum Impurity in the Air of a
Room?

It is 06 per cent of carbonic acid.
28

What does this Amount Include?

It includes the “initial” carbonic acid—viz,, ° ‘04 per cent.,
that exists in pure air naturally, and the ‘Tepes carbonic
acid—viz., ‘02 per cent.

* How much Air per Head per Hour is Required to keep up this
Purity?
It requires 3000 cubic feet of air per head every hour to.
keep up this standard.

How does this Affect the Space Required? —

The space ought to be such that this amount of air can be
passed through it for every person in the room every hour,
without perceptible draught, as a draughty room is not a
properly ventilated one.

How Often may the Air in a Room be Changed per Hour?

Jt may be changed three or four times an hour, but that is
all that can be borne in this country unless the air be artificially
warmed; hence, of course, the smaller the amount of space the
oftener must the air be changed in order to secure 3000 cubic
feet per head per hour.

What Space should be Allowed therefore?

From 750 to 1000 cubic feet per head. It is almost impossible
to ventilate “without” draughts if there is less than 600 cubic
_ feet per head. If the air be heated before it passes into the
room, and if the ventilation be perfect (which it never is), then
400 cubic feet might do. Aim, if possible, at 1000 cubic feet
per head.

Note, then, these Three Points,
1. The limit of maximum impurity is ‘06 per cent, of carbonic _
acid,
2. That we require 3000 cubic feet of air per heutt per hour
to keep up this standard of purity.
p 29
3. That we should, if possible, allow 1000 cubic feet of space

per head, as this will only necessitate three complete changes | .

of air per hour. If the space be 750, the air must be changed
four times per hour, as 4 x 750 = 3000. In estimating cubic
space allow 3 cubic feet for each person and 10 cubic feet for
each bed.

How would you Calculate the Required Amount of Air?
Let
e = the quantity of carbonic acid exhaled by an adult per

. hour—viz., °6 cubic feet.

r= the ratio per cent. to which it is desired to reduce the
vitiation—viz., ‘06 per cent.
R=the carbonic acid naturally existing in the air—viz.,
"04 per cent.
Then —*
rt
feet.
Reduce all the terms to cubic feet,
and r = ‘0006 and R = ‘0004, and so
6 ‘6  _ 6000

0067 O00 = DOI= 7 = 3000 cubic feet

per head per hour.

 

E- the required dilution of air per hour in cubic

How Fast must the Air go to Cause a Draught ?

Air at a temperature of 55° to 60° F., moving at the rate of
14 feet per second, does not cause a draught.

At 2 or 24 feet per second some people will feel a nen
but not all.

At 3 or 34 feet per second all can feel the draught.

If the air be warm it may move faster without causing, a
draught.

What Follows from this ?

That we must aim at having that amount of cubic space,
and an area of inlet for fresh air, that the currents will not need
to travel faster than 1} feet per second,
80

What Space is Allowed for Women and Children?

The same as for adult males—3000 cubic feet—unless in the
case of children under five years of age. Asarulea child should
' get as much space as an adult.

What are the Different Forms of Ventilation ?

1. Natura VENTILATION —i.e., by forces which are con-
tinually acting in nature, as diffusion, winds, and differences
in temperature.

2. ARTIFICIAL VENTILATION—1.¢., by forces set in action by
man. The air—

(a) May be drawn out = the “vacuum method,” or
(6) May be forced in = the “ plenum method.”

What are the Means of Natural Ventilation ?
1. By diffusion of “gases ;” the organic impurities de not
diffuse as they are not gaseous,

2. By winds.
3. By differences in weight and volume of masses of air of

unequal temperature,

How does Diffusion Act ?

Gases diffuse into space or through porous substances at a
rate inversely proportional to the square root of its density, and
therefore the lighter the gas the faster it diffuses.

Is the Hifect of Diffusion, as a Ventilating Agent, very Marked ?
Not very, but still appreciable ; thus, the diffusion through—
A square yard of sandstone is 5-7 cubic feet per hour.
A square yard of limestone, 6°5 cubic feet,
A square yard of brick, 7°9 cubic feet.
A square yard of mud, 14:0 cubic feet.

How does the Wind Act ?

1. By direct action, blowing through and through (“ perfla-
tion”), as in cross ventilation of large rooms, and hospitals with
31

windows on both sides of the ward. This plan is very apt to
be draughty ; it rushes in through open doors, windows, ete.

2. By diffusion through the walls of houses.

3. By its aspirating power, as blowing over a chimney ; the,
moving air causes a partial vacuum or rarefaction in its path, and
then the air naturally is forced from the place of greater pressure
to that where it is less; the wind therefore causes a current at
right angles to itself up the chimney.

What are the Objections to the Wind as a Ventilating Agent ?
1. The air may be stagnant.
2. Its movement is very uncertain and it is difficult to
regulate.

What do you mean by “ Still” Air?

Air is often called still when it is moving at the rate of 1 or
14 miles an hour.

What is the Average Rate of Movement of the Air in this Country ?
From 6 to 12 miles an hour.

Explain how Wind may impede Ventilation ?

Because air in motion (“ wind”) has weight, and it thus may
impede the exit of air from a tube, as it may actually blow down
the tube, according to the direction and angle of inclination of
the wind current.

Moving at the rate of 7 miles an hour, the wind exerts a
pressure of 4 ounces to every square foot.

At 10 miles an hour, 8 ounces.
At 14 miles an hour, 16 ounces or 1 pound.

This is one cause of smoky chimneys, and a state of matters
much helped by the use of cowls turning from the wind.

What are the Different Ways of Using the Window in Ventila-
tion ( Perflation ).

1. The windows may simply be opened. When this plan

is adopted they should be opened both at top and bottom to
32

obviate the sulle arising from draughts. By this plan _
the cold air is apt to pour in like a cascade on people’s heads, .
and not mix equally with the air of the room but make for the
nearest outlet in a stream.

2. The top of the window, or a part of it, may be made to
slope in when opened; this plan directs the current of cold air
up towards the ceiling, so that it will be warmed before it
descends, and then mix more equally all through the room.

3. May have a glass louver in the top centre pane.

4. May use double panes, the outer one open at its lower
border, and the inner one open at its upper border; here again
the current coming in will be directed upwards towards the roof,
the double panes, too, lessen to a great extent the loss of heat
- through the glass.

5. Potts’ plan was to make use of panes of perforated glass.

6. Dr Bird’s excellent plan is to raise the lower sash, insert
a piece of board so as to completely close up the opening thus
made ; in this way the fresh air comes in at the middle between
the sashes and is directed upwards towards the ceiling.

7. Boyle’s plan is to have a pane to open and shut by a
spring. ,

8. Another plan is to have a wire screen at the top, that
unfolds when the window is pulled down, and folds up when
it is shut; this ensures minute sub-division of the incoming
current, the difficulty is that the meshes are apt to be clogged.

Why are Double Windows Warmer than Single ?

Because between the two windows there is a layer of still
warm air, so that the glass of the inner window is much warmer
than the air outside.

What Happens with Single Windows ?

In a cold day the glass is as cold as the air outside, and
when the warm air in the room impinges upon it, the air is
* eooled down and rendered heavier, and so falls down upon
the persons in the room. This alone is une to cause an
uncomfortable “ draught.”
33
What are the Advantages of Shutters ?

With shutters an ordinary window is like a double window,
and therefore much warmer. Shutters are good for warmth,
quiet, and sleep.

What was Sylvester’s Plan ?

It was a plan used in Derby and Leicester more than fifty
years ago; it is both perflation or blowing in, and aspiration
or sucking out, by means of properly arranged cowls. A large
cowl is made to force the wind, by means of a vane; into this
the wind blows (‘ perflation”) and is conducted by a shaft to
the basement of the building, where it could be heated by a
stove, hot plates, or hot pipes, if necessary. This entrance
shaft may either be near the building, or at some distance from
it, according to the purity of the air, and its height will also
vary for the same reason. From the basement the air is led
by tubes to the various parts of the building, and then makes
its exit through tubes projecting above the roof, fitted with
cowls turning from the wind (“aspiration”).

Who else Adopted a Similar Plan?

Dr Arnott for the Field Lane Ragged School, the exit cowl
being a little higher than the entrance one in order to increase
its extractive power.

What are the Objections to this Plan? _

The movement of the air is unequal and difficult to regulate.

How is the Wind used to Ventilate Ships ?

In a similar manner, either by means of a canvas tube held
open by means of hoops and fixed so as to face the wind (wind
- sails).or by tubes fitted with cowls turning to the wind; in this |
way the wind is forced down between decks and into the hold
and to the furnaces in steam-vessels,
c
34

What are the Difficulties in this Plan ?

It is difficult to distribute the air so that it will not cause
draughts; to help this object the tubes may be bent two or
three times at right angles, and the inner end of the tube
enlarged and fitted with wire gauze to subdivide the air, or
valves to partially close the opening.

What is Potts’s Plan ?

_ It consists of a perforated hollow metal cornice running
round the whole room, and divided longitudinally throughout
its whole length into two separate channels by a plate attached
to the lower one; the fresh air is admitted through openings in
wall into the lower channel, and falls imperceptibly into the
room through the numerous perforations. The upper channel
communicates either with the smoke flue or with a ventilating
shaft, and the foul air passes into it through the numerous
perforations.

Is this a Good Plan ?
Yes; Mr Robson, architect to the London School Board,
speaks very highly of it. The cold air too readily descends
. from the lower channel, while the foul air being lighter rises to
the roof, and easily enters the upper channel.

What is Mr Varley’s Plan?

It consists of a perforated zinc tube, communicating with |
the external air, passing along the cornice of three sides of the
room, while on the fourth side is another perforated tube, con-
nected with the chimney.

What is M‘Kinnell’s Plan ?

It consists of a tube within another, the open areas of which
are equal. The inner tube is the outlet, because the outer one
. keeps it hotter and causes an up-current; it is also the higher
of the two, and should be fitted with a cowl turning from the
wind. The air entering the outer one is thrown up like a spray _
35

towards the ceiling by means of a flange. Both tubes should
be situated in the centre of the ceiling or roof. If there is a
fire in the room, both may become inlets; and if the doors or
windows are open, both may become outlets.

What is this Method best Adapted for ?

It can only be used in upper rooms or one-storied buildings.
It is best fitted for square or round rooms, or small churches.
It is not so good for long rooms.

What is Stallard’s Plan Sor Workshops and Factories ?

It is to have a double ceiling, the lower one consisting of
perforated zinc or oiled paper. The air space between the two ,
ceilings should be open to the atmosphere on all sides.

How does Unequal Weights of Air Act ?

This is the cause of the wind itself. If the air in a room
be heated or made moister, it expands and endeavours to
escape, because, bulk for bulk, it is lighter than the external
air, and it therefore passes out, or rather is forced out, and the
cold air passes in, to be in turn heated and again be pressed out.
The air expands one part in 491 from 1° F.

What is the Pressure of the Atmosphere ?

It is 14 lbs. on the square inch—ze., it is the weight of a
column of air, an inch square, and five miles in height.

With what Force would this Rush into a Vacuum ?

At a velocity of 1339 feet per second, as the velocity in feet
per second of falling bodies is almost equal to eight times the —
square root of the height through which they have fallen. In
this case the height is five miles.

But a Room is not a Vacuum, how fast will Air Rush into it ?

In this case the velocity will be due to a height that repre-
sents the difference of pressure outside and inside.
36 ©

' | What is 3 tha Rule’ 2

The height from the aperture at which air enters to that froth
which it escapes, multiplied by the difference of temperature
between the outside and inside, and divided by 491; this will
give the difference in pressure outside and inside.

Let the height be 20 feet, and the difference of temperature

_ 15° F., then—
20 x15
491
and eight times the square root of this = 6°248 feet per second,
per square inch, as the velocity of the inflowing current.

 

= 0°61 of a foot,

Will this be the Real Velocity ?

No; we must allow a fourth, or a third, and in some cases a
half, for friction. The lessening due to friction is in proportion
to the length of the tube. Angles greatly increase the friction.

What Total Size of Inlets and Outlets should be Allowed? ©

About 24 square inches per head for inlet, and the same for —
outlet; but it is necessary to have some means of lessening or
closing these inlets in very cold weather or in high winds.

“Where should the Inlets be Placed ?

They should be so placed as to be fed with fresh air from a
pure source; they should be short, direct, and easily got at to
be cleaned; they should be small and many, rather than few
and large—48 to 60 square inches should be the maximum
size. The end towards the room should be trumpet-shaped,
' or expanded so as to mix the air; and if placed above the heads _

of the people, the current should be directed upwards towards
the ceiling, and be finely divided. The outer end must be
‘protected from wind and rain and have some means of partly
closing it. Wire gauze at the inner end will also help to sub-
divide the current. They must not be placed too near an outlet
- or else the current will sweep right through ; theoretically they
37

should be placed low down, but if so, the air would have to be

heated; if the air is not heated it must be let in above the heads’
of the people, about 9 or 10 feet from the floor, and be directed

upwards towards the ceiling. The air may be filtered through

‘cotton wool or muslin or flannel, or it may be made to pass over

trays of water if it be too dry.

Where should the Outlets be Placed ?

If artificial heat cannot be used to aid the extraction, they
should be placed at the top of the room ; if artificial heat is to
be used they may be placed at any convenient point. Without
artificial heat they are to be placed at. the highest points and
the tubes should be as far as possible enclosed within walls, and
not outside an external wall, so as to keep the air from being
cooled and falling back into the room, or allowing the moisture
to be condensed and running down the pipe. They should be
as straight as possible, without angles, and should be quite
smooth in the inside. They may be round or square, and
should have a cowl at the outer end turning from the wind
to assist by aspiration, and prevent rain passing in, and lessen
the chance of down draughts,

What are the Causes of Down Draught ?

1. The wind may blow in and force the air down.

2. Rain may get in and evaporate and cool the air so that it
becomes heavier than the air in the room.

3. The tubes exposed to cold, as when they are placed on
the outer side of an external wall: this again cools the air and
~ renders it heavier.

4, There may be another outlet with greater discharge,

. How may Artificial Heat be Employed to Assist Extraction ?

By a chimney and open fire: surround the smoke flue with
foul air shafts ; a gas jet may be used to warm the outlet. An
ordinary chimney is enough for three or four persons,
38
What Plans are sometimes Adopted for Inlets ?

Perforated bricks are used sometimes; so gratings, and the
Sherringham valve. The Sherringham valve is one of the best;
it closes at will by a balanced weight, and slopes inwards and
upwards when open. The outer end is guarded by a perforated
brick or zinc grating; the air passes through the perforations
and is then directed upwards towards the ceiling.

What is Tobin’s Plan for Inlets ?

It consists of vertical tubes carried for a certain distance—
fully 6 feet—up the walls of the room, so as to obviate the
discomfort from down draughts. The tubes may be closed at
_will, and they usually open at a little distance above the heads
of the people, and the current is directed obliquely upwards
towards the ceiling. It is a very good plan for rooms or class-
rooms with windows only on one-side, but may be used for any.
large hall or church.

What is Arnott’s Chimney Valve ?

It is an opening into the chimney near the ceiling, so that
the air from the top of the room may readily enter the smoke
flue. The objections are that it may allow reflux of smoke or
soot into the room, and is sometimes a little noisy. It should
have a valve, set at an angle, of talc or mica plate, to prevent
reflux; and to avoid the noise, Mr Crossley has introduced his
patent noiseless ventilator, the valve of which is nicely balanced
by a ball of metal attached to a lever which rests on pivots.

How is Ventilation carried out in the Army ?

By means of shafts carried 4 to 6 feet above the roof, with

a louvre at the top. They are made of wood, and are smooth,

and have a flap to close it partly below.

1. On the ground floor, the area of the tube is 1 square inch
for every 60 cubic feet of space, or 10 square inches for each
man:
39

2, On the first floor it is 1 square inch for every 55 cubic
feet of space, or 11 square inches for each man.

3. On the second floor it is 1 square inch for every 50 cubic
feet of space, or 12 square inches for each man.

In addition to this there is the chimney, which, with Galton’s
stove, gives a section area of about 6 square inches for each man.
The total outlet, therefore, varies from 16 to 18 square inches.

Should the Exit Tubes be all one Height ?

Where there are several ventilating tubes used, they must all
be of the same vertical height, otherwise the highest will impede
the action of the lowest.

Should the Inlets or Outlets be the Larger ?

The openings for the admission of fresh air must be as
large or even larger than those for the escape of foul, otherwise
counter currents may set in and interfere with the exit and
cause draughts, and cool the foul air and let it fall back into
the room to be breathed ever again.

Whether is Ventilation more Difficult in Summer or Winter ?

It is much more difficult in summer than in winter, and
‘therefore one must see that there are sufficient tubes for summer
use, and close up some of them during winter.

What is the Best Form of Ceiling ?

A flat level ceiling is “not” good for ventilation, and is
still worse if in coffers. It should be dome-shaped, or like a
truncated pyramid, the centre being the highest point. In flat
or coffered ceilings there is much of the foul air left at rest,
which collects in the corners, etc.

What ts the Best Form of Ventilation ?

The kind that is spontaneous, self-acting, always in place,
cheap, easily provided, that does not easily get out of order,
and that requires no care from the inmates,
40

When is Foul Air most Harmful ?

The breath poison, like the malarial, chiefly affects persons
at night, though it is formed most during the day. During the
day the sun warms the earth and causes ascending currents ;
‘but at night the earth is cold, and the poisons lie close, to the
ground, and are not dissipated as during the day.

What Follows from this?

That sleeping rooms should be high, and take their air,
supply from a point at some distance above the surface of the
ground, More especially is this necessary in malarial regions ;
and in the absence of tall enough houses, or no houses at all,
the traveller should sleep in a tree all night.

What ts the Main Artery of the House as regards Ventilation ?

The staircase; from this the rooms are supplied and the fires
fed, hence the staircase should be cut off from the basements
and be provided with plenty of fresh air.

How should a Common Stair or Lobby be Ventilated ?

1. By the door itself. ,

2. By the fan-light above the door, which should be kept
open night and day in summer. In this way the various rooms
would be ventilated and the fires fed. In winter the air in the
lobby should be warmed.

Give Examples of Artificial Ventilation on the “ Vacuum
Method ?”
The air may be “ drawn out” on the extraction principle by—
1. Heat—e.g., the common chimney.
2. Steam jets.
3. Fan or screw.

What ts the Objection to the Common Chimney ?

Much of the heat is carried up the chimney, and is said to
be thus lost; probably seven-eighths pass off in this manner,
41

It is not altogether lost, however, as this lost heat serves as
a very efficient ventilating agent, Henan a good deal of fuel no
doubt is wasted.

How does the Fire Feed itself. with Air?

The air rushes towards it from the doors and windows, and
any other opening; but if the doors and windows are too tight
the fire will feed itself by causing a current down the chimney,
and this current enters the room in puffs carrying smoke with it,
this being one cause of smoky chimneys. To cure this provide
proper inlets. ‘

What is the Course of the Air Currents Feeding the Fire ?

The air enters say from beneath the door, passes towards the
fire-place, where it is heated—one part passing up the chimney
with the smoke; while the other curls up in front of the fire,
and back along the roof where it cools, falls down, and is again
drawn towards the fire-place.

Is the Room thus equally Warmed and Ventilated ?

No ; as the air entering is cold, the end of the room opposite
the fire is too cold, and the cold current along the floor chills
the feet, and besides the foul air is not properly mixed and
carried away.

Is the Chimney a sufficient Ventilator ?
Yes; it is outlet enough for four or five persons.

Where should Fire-places be Placed ?

They should be grouped in the centre of the house, because,
if in an external wall, much of the heat is lost by radiation.

How is the Waste of Fuel in an ordinary Grate to be Overcome ? .

By using the stove or grate designed by Captain Douglas
Galton.
42 :
Give a short Description of this Grate ?

It provides an air chamber at the back in which the air is
heated before it enters the room. If it be built on an outside
wall the air can pass directly into the air chamber, but if it be
on an inner wall a special fresh air channel must be provided
to feed the chamber. On the back of the stove projecting into
this air chamber are large flanges to increase the heating surface.
The smoke flue also passes through the chamber and helps to
heat the air too; the flue then becomes continuous with the
chimney. The fresh heated air enters the room at a louvred
opening, at a point between the fire-place and the ceiling, or by
two such openings—one on each side of the chimney breast.

' What are the Advantages of this “ Grate”?

1. It may be made to fit into existing fire-places.

2. It has the same cheerful appearance as the ordinary grate.

3. It produces the same degree of warmth in the room as an
ordinary grate, but with one-third the quantity of fuel.

4. The temperature of the room is more equable, and
draughts are avoided.

Mention some of tts Rivals ?

1. Boyle's grates, where the heated air enters through open-
ings along the top of the grate.

2. Shortand’s Manchester grate, where the heated air enters
through the shelf of the chimney-piece, or may he conveyed by
special tubes to bedrooms above.

How can Ordinary Grates be Improved ?

In order to economise fuel, the stream of cold air passing
through the “‘bottom” of the grate should be cut off, either by
using solid fire-brick bottoms as in Parson’s, Abbotsford, and
Kryle grates, or as Mr Teale has pointed out, by closing up
the open chamber under the grate by a close-fitting shield or

_ door, which aay blacksmith can make; these shields he calls
* economisers,”
43

What are Mr Teale’s Rules for Fire-places ?

1. Use as much fire-brick as possible in their construction.

2. Make the back and sides of fire-brick.

3. The back should lean or arch over the fire.

4. The bottom of the fire or grating should be deep from
before backwards—not less than 9 inches for a small room.

5. The slits in the grating should be narrow.

6. The bars in front should be narrow.

7. The chamber beneath the fire should be closed in front

‘ by a shield or economiser, or an iron plate may be used instead

to fit the bottom of the grate and laid on the bars.

How could you Assist the Ventilation of a Room by a Common
Chimney ?

By introducing Dr Arnott’s chimney ventilator, or Crossley’s
noiseless ventilator, or have a flue entering at the ceiling and
running alongside the chimney.

How could the Air in Large Houses be Easily Heated ?

By having coils of hot-water pipes, or stoves in the halls
and staircases; from this, the chief artery, the heated air can
then be admitted to the various rooms.

What are the Objections to Stoves ?
They are apt to dry the air too much.

How can this be Helped to a Certain Extent ?

By having a dish with water on the grate, to evaporate;
or coat the iron with silica.

How are Large Buildings best Ventilated ?

By having coils of pipes to heat the entering air, and then
having a large foul air extraction shaft or shafts, heated by a
furnace at the bottom, into which the foul air flues from all
parts of the building are conducted—e.g., asylums and prisons.
44

How is the Council Chamber of the Guildhall, London, Ventilated 2

It was ventilated by Messrs Doyle, by means of a number
of vertical shafts for the inlet of fresh air; the outer ends of
the shafts project about 3 inches from the wall, while the inner
ends open into the chamber at different heights so as to dis-
', tribute the air equally. The shafts are fitted with heaters which
are warmed by means of a gas jet fixed to the side of each shaft
and enclosed in a metal casing, and in this way the air entering
can be raised to any temperature by raising or lowering the gas
jets, and a constantly induced current of fresh air be kept up
whatever the temperature of the outside air be. The foul air
is extracted by shafts springing from various parts of the ceiling
through roseate perforations, converging to patent exhaust cowls
on the roof.

How are Coal Mines Ventilated ?

Also on the extraction principle; a furnace is kept burning
at the bottom of the “up-cast shaft,” and in’ this way a fresh
_ supply of air is drawn down the other shaft and made to traverse

the various galleries by an arrangement of partitions and double
~ doors which can be opened and closed at will.

How much Atr is Required in Mines ?

At least 2000 cubic feet per head per hour in well ventilated
mines, but in mines with much fire-damp it ought to be 6000
cubic feet.

If the Mine has only one Shaft, how is tt Managed ?
No mine ought to have only one shaft, but the single shaft

‘could be divided into two by a partition, one half being “down-

cast,” the other “ upcast.”

What ts “ Fire-Domp ug

It is a gas, known also as marsh-gas, as it is produced in
marshes by the decomposition of vegetable organic matters, as
leaves, wood, etc., in marshes and stagnant pools; and this also
45

has been its source in the coal seams during the processes
necessary for the formation of coal from vegetable matters of
bygone ages. Chemically it is known as hydride of methyl,
HCH, or CH,. It has no smell, colour, or taste, and therefore
the unaided senses alone cannot detect its presence in a mine.

How then can it be Detected ?

By means of the “safety lamp”; the gas passes inside the
gauze to the flame, and burns round about the flame of the
lamp with a bluish-yellow light—the “corpse light” of miners,
When this is the case, then this part of the mine should be
swept by the ventilating current, or else the workmen should
leave it altogether for a time.

What Volume of Air is Required to make the best—or rather
the worst—Explosion ?

Ten volumes of air to one volume of marsh gas: this would
form the most complete and destructive explosion.

What takes place when it Explodes?

: Carbonic acid and water are formed, and the mine glows
. like a furnace from the ignition of the fine coal dust in the air
of the mine.

What is the “ After-Danyp” ?
It is the carbonic acid, and it is as much to be dreaded as
the “ fire-damp,” as it kills by asphyxia.

How is it that a Fall of the Barometer indicates Danger to a
“ Fiery” Mine ?

Because the fall of the barometer indicates a fall in the
atmospheric pressure. Now, as long as the atmospheric pressure
is greater than the pressure with which the fire-damp tends to
escape from crevices in the coal seams, the fire-damp is im-
- prisoned. as it were, and only escapes by diffusion and from the
46

ordinary “makings ;” but when the atmospheric pressure falls
below the pressure of the fire-damp, then it issues freely from
the cracks, etc., in the coal seam; and this is what takes place
when the barometer falls below a certain point.

How is the Foul Air Removed from Ships ?

By means of tubes from all parts of the ship, opening into
the ash-pit beneath the cooking furnaces, and when the furnace
doors are closed the foul air is then drawn from all parts of the
ship to feed the fires. Another plan is to have an iron casing
surrounding the bottom of the funnels and upper part of the
boilers and steam pipes, leaving a space of three or four feet
between the casing and the pipes, and when the fires are lighted
there is a great draught, this arrangement acting as an extrac-
tion shaft, so that even the hold can be thus ventilated, and the
temperature of the stoke-hole is reduced from 130° to 60° F

What Plan is often used in Theatres and Churches ?

Chandeliers and “sun-burners” and other gas jets, and the
new “ventilating globe light.” In chandeliers and sun-burners —
there is a large central shaft surrounding the tube, taking off the
burnt products; and entering this outer tube are smaller tubes
taken to it from all parts of the building, and in this way when
the gas is lit there is a great draught.

How much will an Ordinary Gas Jet Discharge ?

One cubic foot of gas will produce heat enough to discharge
1000 cubic feet of air, and as an ordinary burner will burn: °
3 cubic feet per hour, the ordinary burner will thus discharge
3000 cubic feet; but unless the products of its own combustion
are removed at once by proper tubes over the jet, it will vitiate
9000 cubic feet per hour.

Is Extraction by Steam Jet much Used ?

No, it is almost given up: it might be used in factories
where there is plenty of spare steam.
47

How does it Act ?

The jet or cone of steam will throw a body of air 217 times
its own bulk into motion.

Is the Fan or Screw much Used ?

No; but the Archimedean screw may be used for small air
shafts and factories: it is said to draw the air out. The fan
is used in mines, and has been made to extract as much as
45,000 cubic feet of air per minute. It is also used in mills
where there is much dust as in Manchester, and also in paper
mills at some stages of the rag preparation. It is also used, it
is said, at the London Club, where it extracts at the rate of
1000 cubic feet of air per minute.

Give Examples of Ventilation by Propulsion.

1. By a fan or wheel enclosed in a box with a pipe passing
from it. (Desaguliers in 1734).

2. Arnott’s piston and cylinder, or his gasometer pump,
worked by hydraulic pressure.

3. The “ punkah” in India.

What is the “ Punkah” ?

It is simply a gigantic fan, suspended above a table or bed,
a line passing from it to the attendant outside, who pulls it and
thus sets the air in motion. The punkah may also be moistened,
and this increases its effect very much as the air is cooled’ by
the evaporation of the water.

< What is the Van Hecke System ?

It is a method used in France and America for the ventila-
tion of several large hospitals; the air is forced by a fan into a
basement chamber, where it is heated before it enters the wards.

_ Give an Example in this Country where Propulsion is Used on
the Large Scale.

‘St George’s Hall, Liverpool. The air is taken from the
48

basement and is washed by passing through a film of water
thrown. up by a fountain ; it is then passed in cold weather into
vessels for the purpose of heating it, and in which it can be
moistened by a steam jet whenever the difference between the
dry and the wet bulb exceeds 5°, and it is propelled along
different channels into the hall. In summer the air in these
“conduits is cooled by the evaporation of water.

What is the Best Form of Ventilution ?

On the whole, natural ventilation is the best; of the artificial
forms, extraction is better than propulsion, as regards cost,
efficiency, and stability. :

What are the Advantages of Propulsion ?

1. The certainty and ease with which the amount thrown in
can be altered.

2. The air can be taken from any point, and can be washed, :
filtered, cooled, and heated, at pleasure.

What are its Disadvantages ?
1, The great cost.
2. The chances of the engine breaking down.
3. Difficulties in distributing the air properly.

What Method was Used for the House of Commons long ago?

Desagulier’s plan was started in 1734, and was kept up thus
till about 1820. It was turned by a man, arid would either
blow in or suck out according to the way of turning.

What are the great Objections ?

It needs a man to turn the wheel, and is therefore apt to
be neglected; and is thus not always ready, not always in its
place, and often neglected when most needed—e.g., during a
heated discussion when there is usually a good deal of foul air
about,
49
What Points have to be Attended to in Fitting up a Fan?

It should. fit the box well, and have six or eight rays, and
the vanes should be fully one-half the length of the rays. It
acts most efficiently when the extreme points of its vanes move
about 80 feet per second, and the velocity of the issuing current
is about three-fourths of this, and this multiplied by the area
of the discharge pipe in square feet will give the cubic feet
discharged per second. An excellent wheel is Blackmann’s
“air propeller.”

How much Air does it Require to make a Pound ?
13 cubic feet.

What is Dr Chowne’s Plan of Ventilation ?

By means of an inverted syphon. The syphon in air acts
in a way the reverse of its action in water—the air goes up
the long leg and down the short. The chimney is the long leg,
and the short leg begins near the ceiling. This plan requires
heat to make the air in the long leg ascend.

- Before Desagulier’s Plan in the House of Commons, what Plan
was Tried ?

By means of artificial heat at the upper part of a ventilating
shaft.

What was the Cause of the Failure ?

The personal enmity and ingenuity of Mrs Smith the house-
keeper. She would not kindle the fire till the house was well
heated, and then, of course, the draught went the wrong way
and made the house hotter instead of colder.

‘What is Sutton’s Plan for Ships ?

A fire is kept burning, and pipes are brought from the part
requiring ventilation to feed the fire, and this causes an inrush
of fresh air: the pipes open into the ash-pit; or a large central
trunk could be used to feed the furnaces of the boilers, and pipes

pass from this to all parts of the ship.
D
50

How else ts this Plan Adopted ?

It is used to get rid of the effluvia arising from soap-boiling,
_ tallow-melting, etc. A pipe passes from the lid of the vessel to
- the ash-pit. :

. Nors.—Sutton’s method for ships, and Desagulier’s method
for the House of Commons, are good examples of the principle
of ventilation by artificial heat—extraction, or the “ vacuum
method.”

What was Dr Reid’s Method for the House of Commons?

There was a chamber beneath the house with a passage, and
into this passage two other passages of equal width opened, in
one of which is a warm water pedestal. The two passages have
folding doors that can be shut and opened, and on this the
temperature of the House depends— the one giving all warm
‘air, the other all cold, and so by adjusting the doors you can
‘get any mixture you like as to temperature, and any amount
you please. The fresh air enters the passages from Old Palace
Yard through a grating. The air thus prepared rises through
the floor of the House by a number of apertures, with platforms
over them to spread it, and then through openings in the actual
floor of the House, about 300,000 in number, and of the shape
of a truncated cone, with the narrow end upwards, to check the
dust and prevent them being choked up. The sides of the
House are brought forward, and the air passes up behind to the
Members’ galleries, where it enters in a similar manner. Over
the floors of both is a thick horse-hair mat, with big meshes to let
the air through. The force setting this air in motion is a large
ventilating shaft, at the bottom of which a fire is kept burning.
In summer the air was cooled by sprays of water, or by ice

_ hung in mats, just after it came through the grating from Old
Palace Yard. There was a second ceiling a few feet below the
original one, divided into three parts—a central and two side
parts. The side parts are glazed and slope at an angle of 30°
with the floor of the House; so also in the Members’ galleries:
The centre part of the ceiling is panelled, and each panel can
51
be raised several inches above their styles, and this lets the foul
air in between the roof and the ceiling. A large square shaft
passes from the hole between the two ceilings and joins the
tall ventilating shaft, in which a fire is kept burning, about ten

feet from the surface, and the draught can be regulated by a
“ damper.”

What is the Objection to this Plan ?

The dust is drawn up by the current from the haircloth
. carpet and is inhaled. To purify the air from the Thames
effluvia, the air may be treated with water sprays, or filtered
through canvas soaked in chloride of zine or bleaching powder,
or when very offensive through charcoal.

‘

‘What has to be Specially Provided for in Lighthouses ?

1. The large amount of water produced—20 pints per hour—
which condenses and freezes on the glass and dims the light.

2, The large amount of carbonic acid produced, which affects
the health of the keepers.

How ts this Carried Out ?

It was remedied by Faraday, who caused a central chimney
to be constructed through the roof of the lantern into the open
air, the upper end of the tube being protected by some kind

_of covering; then over the glass chimney of each lamp was
placed one end of a small tube, and this tube was then curved
up and opened into the central chimney. These tubes carried
off the watery vapour and carbonic acid.

What is Major Jebb’s System for Prisons ?

In the basement story is a large hot-water case or boiler,
which warms the incoming air; the air then passes by flues
under the corridor floor of the prison, and from this a small
flue branches off to each cell and enters at ‘‘the top” so as to
avoid draughts as the space is confined, and also to prevent the
occupant. of the cell from plugging up the opening. The foul
ee

air is extracted near the floor by means of a grating diagonally _

opposite the inlet flue; the small foul air flues join the main

flue placed on the roof, which ends in a shaft rising above the |
top of the building. In summer the air enters at the natural -

temperature, and a fire is lighted when necessary in the venti-

lating shaft, but in winter a fire is lighted in the heating

apparatus in the basement, and the heat from this passes up
the shaft and creates an up-current that ventilates.

How ts the General Post Ofice, London, Ventilated ?

It was ventilated by Mr Cowper by means of a large main —

trunk communicating with the open air at the top, while at the

bottom of the main is a large fan driven by steam power, which ©

forces air through the main at the rate of 30 feet per second.
The air on entering the main is filtered by three screens placed
vertically, with pockets beneath to catch the dirt; the screens
consist respectively of 12, 16, and 20 meshes to the linear inch.
The meshes become choked up with dirt in about three days
and have to be cleaned with a brush. From the main, branch
mains are given off to each room ; and from these, branches pass
fed by holes three-quarters of an inch in size: these smaller

tubes are perforated, and ramify all under the tables and where-

ever required. The rate of the current is about a foot and
a half per second in these branches, and no draught is felt. The
foul air is got rid of by suitable openings at the top of the room,
and the products of combustion from the gas are removed by
placing a funnel near each gas flame.

’. What are the Special Points about Inlets and Inlet Channels ?

‘1. The air should enter with a low velocity.

2. It should come in a little above the level of the heads of
the people.

3. It should be directed upwards towards the ceiling.

4, It should be minutely sub-divided.

- ‘When the inlets are “near the floor” they give rise to cold,
atid are also apt to become choked up ; if “near the roof,” they
53

soon cease to exist as a distinct current. The inlets must be
taken from a fresh source and about 2 feet from the ground,
the surface near being paved and sloped away from the wall so
as to carry off the wet quickly. If it is heated artificially, it
should be about 68° to 75° F.—-the average in-door temperature
being about 58° to 66° F. The air channels should be—

1. Short.

2. Direct.

3. Accessible, so as not to collect dirt, insects, etc., and thus

pollute the air.
"4, Filter, if necessary, through frames filled with cotton wool,
or sliced sponge may be used.

5. The shafts passing to each room should be independent
of each other, else foul air may pass from one into the other.
There should be as few turns as possible, and if turns are
necessary make the shaft higher. The circular form is the best,
as it gives the greatest area for the least surface.

How do Underground Channels modify the Air?

The temperature of the air is raised in winter, and lowered
in summer. These channels should be water and air tight, else
the ground air and water will tend to pass in unless the pressure.
of the air inside be greater than that outside.

What are the Objections to Tobin's Tubes ?

There is a good deal of friction; dust, insects, etc., are apt
to collect, and by and by make the air impure; they do not
readily act as outlets should necessity require.

How do you Judge of the Sufficiency of Ventilation ?
1. Measure the space for each person.
2. Investigate the movement of the air, its distribution,
inlets, and outlets, and the amount supplied.
3. Examine the contained air by the senses.
4, Examine it chemically and microscopically, if necessary.
5, Estimate the temperature, moisture, organic matters, etc.
54

In Measuring the Cubic Space, what Deductions have abe to:
— make ?

Allow 3 cubic feet for each adult, and 10 cubic feet for a_
bed, and deduct these from the estimated amount.

How do you Judge of the Dir ection of the Air Currents ?
There are many ways—
: 1. Smoke from smouldering cotton velvet.
2. Fibres of floss silk.
3. Small bits of feather or paper.
4. Ammonia, and hydrochloric acid gas.
5. Hydrogen balloons.

Is the Flame of a Candle Trustworthy ?—

Not when the currents are delicate. It requires a current
of some force to deflect it. It is useful to show whether an
‘opening is acting as an inlet or outlet.

How is the Rate of Movement Determined $

It may be judged of by: —

1. An anemometer. This is like a small sadeaal with
wheels and index, like an ordinary gas meter. It is allowed
to revolve for a known period, and then the number of cubic
feet read off the index, as, of course, the faster it goes the
greater is the number of cubic feet issuing in or out of any
opening. It should be placed in the ‘“‘centre” of the chimney
or air shaft.

2. By a manometer. Judge by the pressure exerted on the
‘surface, and how high the water is raised in the tube.

3. By calculation, by means of Montgolfier’s formula,

4. By the deflection of a candle flame, a deflection of 30° is.
said to indicate a rate of one foot in one or two seconds.

‘". What is the best Time to Test the Efficiency of Ventilation ?

Sometime between midnight and 5 a.m, ~
55

In judging by the Senses (Nose), what is Necessury ?

It is necessary to remain for sometime in the fresh open air
. before entering the room or ward, otherwise the sense of smell
is apt to be blunted.

' How is the Carbonic Acid Estimated ?

By ‘“ Pettenkofer’s method.”—Pure clean lime or bartya
water is used, and a glass vessel holding from half to one and
a half gallons. The jar is carefully cleaned and dried, and
then filled with the air of the room by pumping it in with a
bellows or bellows pump. Then 60 c.c. of clear lime or bartya
water are put in, and the mouth closed with an india rubber
cap, the vessel well shaken, and then left to stand for six or
eight hours. The carbonic acid is absorbed, and to this extent
- lessens the “causticity” of the lime water; as the causticity is
known beforehand, the difference will give the amount of lime
or bartya water that has united with the carbonic acid.

How is the “ Causticity” Estimated ?

By means of a solution of oxalic acid of known strength,
After the carbonic acid has all been absorbed 30 c.c. of the
water is taken and neutralised with the oxalic acid, and this
shows how much has been already neutralised by the carbonic
acid.

How is the Neutralisation Point known ?

By means of turmeric paper; go on till no brown stain is
produced on the paper.

Is any Correction Necessary ?

Yes; correct for temperature, if neceseary. 62° F. is the
standard temperature, and correction is necessary if the obser-
vation be made in a room below-or above this point ; because,
when the temperature is low, the air is condensed and more,
_ therefore, will be examined ; and if high, the air is rarer and less
is examined.
. eye

56

What other Plans are there for Estimating the Carbonic Acid ?

1. May use caustic potash, and then weigh.
2, May judge roughly of the milkiness of lime water by the

3. Angus Smith’s method is easy, and may be applied by
any one. The chief point is that a ten and a half ounce bottle
’ filled with the air of the room, and containing half-an-ounce
of lime or bartya water, should give no milkiness, provided
the air is as pure as it should be—z.e., if it does not exceed
“06 per cent in the air of the room.

How is the Nitrogenous Matter Estimated ?

In the way already described, by drawing the air through

pure water, and then estimating the “ammonia” and the
“‘albuminoid ammonia,” as under water analysis; or draw the
air through a solution of potassium permanganate of known
strength, and then estimate the undecomposed permanganate

by means of oxalic acid. This plan gives the organic matter in

the terms of “oxygen required” to oxidise it,

How is the Watery Vapour Estimated ?

1. By means of the dry and wet bulb thermometer (see
page 14), or

2. By means of the hair hygrometer. This is a human hair
freed from fat by ether or a weak solution of caustic potash;
one end is fixed, and the other is attached to a needle. It acts
more quickly than the dry and wet bulb thermometer.

How are the Sulphidés Detected ?
Sulphuretted hydrogen is best detected by means of blotting-
‘paper dipped in a solution of acetate of lead.
Ammonium sulphide is detected by paper dipped in a solu-
tion of nitro-prusside of sodium.

How would you Examine the Air Microscopically ?

Take a small bent glass tube, wash, dry, and heat it to
redness, and when cool place it in a freezing mixture. An india
57

rubber tube being then fixed to one end, the air is drawn slowly |
through ; the watery vapour of the air is thus condensed, and —
solid particles are carried down with it. A drop of this fluid
is then examined with an immersion lens. In exact analysis
of air, it is first caused to pass through tubes or bulbs contain-
ing caustic potash to remove the carbonic acid; then through
tubes filled with pumice stone soaked in strong sulphuric acid,
to remove the watery vapour; and then through a long tube
filled with bright copper heated to redness, to remove the
oxygen ; and what remains is then read: as nitrogen. The air ,
might also. first be passed through cotton wool to filter it from
suspended particles, and then through distilled water to remove
any ammonia present.

What are the Causes of Smoky Chimneys ?

1. From want of sufficient inlets from other places, and, there-
fore, it comes down the chimney to feed the fire.

2, The fire-place too wide and too high.

3. The chimney too high, and, therefore, the air cools and
falls back again.

4, The chimney too short and too wide. To cure this con-
tract the throat, and make all the air pass through the fire, as
with the large flue the air is not all heated.

5. One flue entering another, and if both are not going at
the same time, the smoke comes down.

6. Chimneys may overpower each other, if there are two in
one room and the fires are not kept equal, or in different rooms
communicating by a door; also, if all the doors and windows
fit tightly, the kitchen fire may overpower all the others.

7. The top of the chimney may be commanded by larger
buildings, or a hill, and the wind blowing over falls down like
’ a waterfall on the top of the vent. To cure this, raise the
chimney, or use a cowl.

8. Improper position of door, it being on the same side as

the fire, and when the door is opened the air rushes past the
i
58
fire and whisks out the smoke. To cure this, use a screen to
protect and direct the current past the fire, or shift the door.
_ 9, Room with no fire filled from another with a fire down
the cold funnel. For this contract, or close the opening entirely,
10. Badly shaped and fanciful chimney pots, with many
points and angles that only increase friction, and deflect the air
- down the chimney.
' 11. Cracked funnel, or a funnel placed in an outside wall.
12. Birds nests, etc., blocking it up.

What are the Objections to open Fire-places ?

1. They waste much fuel, as seven-eighths of the heat passes
up the vent.

2. Unequal heating at different parts of a room: radiant
heat being only one-fourth as great at double the distance from
its source.

3. Cold draughts from the doors and windows.

4. Cold foot bath; because the entering air is cold and
lies along the floor of the room; hence, cats prefer the seats _
of chairs to the floor itself.

5. Bad ventilation.

6. Smoke and dust.

‘7. Loss of time in lighting, if it goes out during the day
and in the morning.

8. Danger to property from fire.

9. Danger to person from fire.

10. Expense of attendance.

Open fires will draw the air from all parts of the house to
feed themselves, as from the basement, water-closets, sinks ; and
unless these are in projecting buildings, and cut off by lobbies
and double doors from the main part of the house, and are also
ventilated from the open air. The staircase is the chief feeder

of the fires and rooms, and, therefore, it should be cut off very

carefully from all sources of pollution, as the basement, water-
closets, and sinks.
er 59
What are the Advantages of the Simple Dutch Stove ?

_ Its simplicity, and it is chiefly used where fuel is scarce.
The heating effect is from the whole surface, and from the
surface of the flue as well, Can make use of almost the whole
heat, without draughts, dust, or smoke.

What are its Disadvantages ?

The air is spoilt—burnt, or has a sulphurous smell; it is also
too dry, and has undergone certain electrical changes. It causes
headaches, loss of appetite, and opthalmia. The flue, also, may
get red-hot and set fire to the house. A dish of water near

the stove helps to rectify the dryness. The metal of any stove - ;

should never be raised higher than 100° F., and never on any
account be allowed to become red-hot, as then carbonic oxide
may escape into the reoom—this gas having the power of passing

through red hot metal; but it also may be formed by the contact
of the carbonic acid of the air with the red-hot metal. The
joints of stoves should be very well made, lest during contraction
and expansion of cooling and warming, they become loose and
let out smoke, carbonic acid, carbonic oxide, etc. An elbowed
flue gives out more heat than a plain one.

Are Stoves Good Ventilators?

No; the air is apt to be stagnant. One pound of coal
requires 150 cubic feet of air for combustion, or say 200; now,
six pounds of coal per day would only require about 1200
cubic feet of air, and this is not enough to change the air once
perfectly. Besides, the slow combustion is apt to produce much
- carbonic oxide, because the draught is small and it may escape
into the room; occasionally, also, marsh gas is produced and
may cause explosions.

 

E. & 8. Lirvinastone, Printers, 4 Melbourne Place, Edinburgh.
CATECHISM SERIES.

 

PUBLIC HEALTH:

 
  

SEWAGE, AND ITS TREATMEN K

—

EDINBURGH:
fh & Ss LIVINGSTONE

1891.
TNC 2.30)

PRINTED BY
E. & 8S. LIVINGSTONE
4 MELBOURNE PLACE

EDINBURGH,
PREFACE.

T is hoped that the method of Question and Answer
here adopted will aid the Student in preparing

his work for Examinations—by suggesting possible
questions that otherwise might have escaped his
notice. In this way the book will be a great and
useful means of self-tuition, The small size of the
book, too, the absence of “packing,” will enable him
to run over the work the night before the Examination,

and recall the most important points to his memory.
PUBLIC HEALTH.

 

SEWAGE, AND ITS TREATMENT.

What is the Best Method of Sewage Removal ?

The water carriage system is best, for large towns at any rate,
if there is plenty of water and good drainage.

What ts meant by the “ Separate” System?

Where there are two sets of sewers, one set for the faces and
urine, etc., and the other for storm water, rain water, and subsoil
water. This plan is used in places that have to provide for the
treatment of sewage, so as to avoid excessive dilution, and
lessen the work at the pumping stations—e.g., as at Dover, Ely,
and Rugby. The set for the feeces and urine, etc., are usually
PIPE sewers ; while the other set for the storm, rain, and subsoil
water are usually DRAIN sewers, and are built of brick.

What are the Advantages of the Pipe Sewer System ?

1. There is no percolation of sewage into the soil when the
pipes are well jointed.

2. They can be quickly laid and require less excavation than
brick sewers.

3. They can be made of various curves for different positions.

4, More easily kept clean.

5. Avoid great dilution of the sewage, and therefore lessen
the expense of pumping, etc., in cases requiring special modes
of treatment.
What ts its Disadvantage ?

Tt does not provide for the removal of the subsoil water,
and in order to keep the soil in a healthy state a special set
of drains are required to dry it; the subsoil water can easily
percolate into drain sewers.

What is the Objection to Brick or Drain Sewers ?

They are leaky, as they let sewage out as well as subsoil
water in, and are therefore a great and constant source of danger
to water mains, the soil, and wells.

How are Sewers Ventilated ?

By means of man-holes and tumbling-bay with double
ventilating arrangment, with charcoal every 300 yards or so,
and lamp-holes at every 100 yards.

Is Charcoal an Unmixed Good ?

No; it is apt rather to impede the ventilation.

What Form is Usually Employed ?

Wood charcoal, in lumps about the size of coffee beans, well
sifted, and not more than three inches thick.

Notz.—The sewers should be absolutely water-tight and not
used to remove the subsoil water—though this mistake, in
Salisbury, was the means of reducing the deaths from phthsis to
a very remarkable extent, by drying the subsoil ; but the liquid
and gases are apt to pass out of the sewers and render the land
“excrement sodden,” and the air “excrement reeking.” In the
case of seaboard towns this is specially bad, because the sewage
is kept back in the pipes by the rising tide for many hours,
and they thus become large cesspools. Still, if the soil be well
drained and erated, it has an almost immeasurable power of
7

cleansing any liquid that may enter or pass through it, and
thus render defective work harmless. Drains should, therefore,
be separate from sewers, and only connected for the purpose of
flushing.

What is a “ Drain” ?

Properly speaking it is a conduit intended to praw out ot
the land through which it passes the water in that land, and
thus remove the wetness and dry the subsoil. In the “ Public
Health Act,” however, it is defined as a “branch sewer con-
necting houses with the main sewer.”

What ts a Sewer ?

It is a conduit for the discharge of filth.

What is a River ?

It is a surface drain.

What is the Relation between a “ Drain” and a “ Sewer”?

A drain should praw in water, while a sewer should be
water-tight ; in some cases, one may act as both.

What ts a “ Drain- Sewer” ?

Where the sewer and drain are laid side by side in the same
trench, as in the “ separate system.”

What is Sewage ?

Sewage is any refuse from human habitations that may
injuriously affect the public health, and consists of—

1. Liquid refuse removed by water.

2. Solid garbage and contents of ashpit, privy, etc., removed
by scavanger.
8
Should Liquid Sewage be Allowed to Flow into Rivers ?

No; it must not flow into rivers even from isolated
dwellings in country places, or even into canals, ponds, or lakes,
until it has been purified from all foul and noxious matters by
the best practicable and available means.

What Amount of Impurity is Allowable to Flow into Rivers ?

Not more than, in parts per 100,000, of—
Organic nitrogen, 0:3
Organic Carbon, 2:0 Dissolved matters.
Metallic Arsenic, 0°05
Mineral, - 3:00
Organic, : 1-0 \ Suspended matters,

What are the Objections to Subsidence Tanks and Precipitation

Methods ?

These methods only cuariry, they do not purify, and besides,
depend on servants. Chemical means are expensive; and
little dependence should be placed on manual service for
constant cleansing. The tank simply forms a big cesspool, and
may not, but very likely will, be a big nuisance, and is nota
good plan for isolated dwellings.

What is a Good Plan for Isolated Dwellings ?

To apply the sewage direct to the land itself, avoiding clay
soils, and under-drain well. The sewage of 3000 or more
persons may be purified by “intermittent downward filtration,”
by one acre, under-drained six feet deep. But the land should
have rest for two years; so use three acres instead of one—
a.e., one acre for every 1100 persons. This plan is specially good
for isolated dwellings and institutions, and will yield some return
in vegetables, crops of grass, etc. If “ wide surface irrigation”
be used, then take an acre for every 100 persons. Whatever
plan be adopted it is better to make it at some little distance—
9

say a quarter of a mile from the dwellings,—so as to avoid the
idea of a nuisance. The surface of the land should be ridged
and furrowed, and into these the sewage flows; while cabbages,
etc., are grown on the ridges.

What is Sub-Irrigation ?

Distribution of the sewage to the land below the surface by
pipes.

Is it a Good Plan ?

Not very; the pipes are apt to be choked up, and the land
becomes “excrement sodden,” and this cannot be detected for
some time after the evil has begun, by the positive wetness
of the land.

How are the Pipes Laid ?

The pipes used are two-inch agricultural drain pipes, placed
ten to twelve inches below the surface on a bed of larger pipes
divided into two equal parts ; the sewage flows out at the joints.
The evaporation and cold produced by this method is bad for
vegetables and human beings alike, just as it is a bad practice
to water flowers from the saucers of the flower-pots.

How should the Private Communicating Sewers (“ Drains” ) be
Made ?

The private sewer connecting the houses with the main
sewer (=the “Public Health Act” prain) should consist
of stone-ware glazed pipes, firmly jointed so as to be water
and air tight, as no water or roots of trees is to get in, and
no sewage to get out. Puddled clay is no good as jointing to
keep out roots of trees, nor in dry soil as it dries and cracks:
tarred gaskin and cement make the best joints. Iscape of
sewage at the joints not only spoils the earth in the neighbour-
hood, but it tends to choke up the pipe, as the liquid passing
through leaves the solid matters. .
10

Should these Private Sewers or Drains be allowed to Pass Under
Houses ?
No, not if it can be avoided, but in some cases it may be
necessary on account of the configuration of the ground.

If they must Pass Under the House how should they be Laid ?

They should be laid under a passage or paved floor embedded
in concrete, and carried from outside to outside, and at each
end a trap with a grated cover should be placed, with means of
flushing. The pipes should be relieved from pressure by arches
as it passes under the walls.

What Course should these Drains Take ?

They should take a direct course to the common sewer; if
this is impossible, then it must pass in straight lines from angle
to angle, and at’ each angle a shaft for ventilation and inspection
ought to be placed. They should be laid on a firm bed of concrete
to prevent sinking.

What is the Risk of Faulty Joints or Cracks ?

On account of the warmth inside the house, the pressure of the
air is less than the outside air, and the outside air will thus press
the obnoxious sewer gases through the soil into the house.

What is the best Form of Junction with the Common Sewer ?

The junctions should be curvep and delivered in the
direction of the main flow, and should enter apovz the average
level of the flow: it may be at right angles in man-holes.

Why is this ?

Because if the junctions be at right angles, the fluid entering
is suddenly brought to a standstill in a series of eddies, and
11

little hillocks of mud are deposited which retard the flow in the
main sewer ; they should open into the sewer at the upper part
of its circumference, above the level of the flow, so as to prevent
the sewage being backed into them from the common sewer.
Further, if the end of the pipes from the houses were always
under water, filth would subside and tend to choke up the
private communicating sewers from the houses (“drains.”) Still,
if the opening be below the water line, the flow in the main
sewer will trap it and prevent the entrance of gases to the
house drain ; but it must not be two low, otherwise the deposit
of sludge that is apt to take place will choke up the end of the
house drain.

What Inclination and Velocity should the Drains have ?

They should be inclined so as to give a velocity of not LESS
than three or mote than ten feet per second; in the case
of the lower velocity, the best glazed pipes should be used.
To secure this velocity in a four-inch drain, give a fall of 1 in
92 or more.

What Size of Pipe should be Used ?

They need not exceed six inches in diameter; they are often
less than this, but four to six inches is a fair size: the larger
the pipe the less fall is required. If the flow of sewage be
faster than four feet per second, grit, stones, etc., are apt to cut
and roughen the sides of the pipe.

What Point has to be Attended to in Connecting Water-Closets
with the Common Sewer ?

If possible, break the continuity of the drain between this
and the common sewer by means of a special trap, with ven-
tilation on both sides of the trap, so as to isolate it thoroughly
from the common sewer.
12
What do you Mean by a Trap ?

It is a name given to any valve which lets water through,
but stops gas or air.

What Form of Trap may be used to Disconnect the House Drain
From the Common Sewer ?

1. Potts’ Edinburgh Air-Chambered Sewer Trap.
2. Buchan’s Trap.
3. Hellyer’s Trap.

These all aim at fulfilling the required conditions—a trap
with ventilation both on the sewer side and the house side
of the trap,—and FRESH AIR can pass through the grating on
the house side of the trap: and pass up the house drain. The
ventilation on both sides of the trap prevents the sewer gas
forcing the trap, and also allows gases that pass through the
water by diffusion to escape into the open air, as well as fresh
air to pass into the house drain.

How should Sink Discharges be Arranged?

The pipe should be trapped inside and should NEvER be
connected pirEcTLY with the common sewer, but discharge in
the open air over the grated covering of a trap or gully, just
outside the wall of the house, and the trap itself should be
ventilated by a special shaft or pipe. A trap is better than a
gully, as the gully allows of a considerable amount of fluid to
remain unchanged for a long time, and this is apt to decompose
and produce gases that might pass up the pipe into the house.
A gully, however, is useful to catch the greasy matters, which
form a very great impediment to the discharge of sewage;
or Field’s flush tank may be used for the same purpose. The
grease should always be intercepted before it enters the
common sewer.
18

How are Gases from the Common Sewer kept from Entering the
House Drain?

Some use a light flap at the junction with the common sewer,
so that the water is said to pass out, but gases cannot get in;
but the ventilating shaft on the sewer side of the disconnecting
trap will usually be found sufficient. If the pipe open below
the level of the flow in the main sewer, it will be trapped and
gases prevented from entering ; but this should not be trusted
to without thorough disconnection of the house drain close to
the house. ;

Give the Size and Position of the Ventilating Pipes.

They should not be less than three inches in diameter, but
better if possible to be four inches; they should be carried up
above the roof, and should not terminate near windows or
close to chimneys, lest gases enter the house. The down pipes
for the rain water should not be used as ventilators—at least as
a rule ; a hood or cowl may be used on the top of the pipe, to
aspirate and prevent the rain going down.

What Arrangements should be made for Flushing the House
Drain?

Flush the water-closets well every time they are used; or
the liquid refuse from sinks may be collected and discharged by
Field’s flush tank, which also acts as a grease interceptor, and
may also collect the rain water from the roofs and the waste
water from the baths, and then empty itself periodically into
the house drain.

What Points are to be desired specially in a Water-Closet ?
1. It must be so placed as to give rise to no bad smell in
the house.

2. The fittings and traps must be good, so that no gases from
the sewer, soil pipe, or trap can escape into the house.
14
How is the First Point Best Carried Out ?

The water-closet should be against an ouTER wall, or in a
little projecting tower with free open-air ventilation, and with
a lobby and ante-room, or passage with cross ventilation between
it and the house, and have double doors—one for the water-
closet and the other between the lobby and the house.

The water-closet should not be near dwelling-rooms, and
NEVER in a bed-room.

As already pointed out, it must have a cistern to itself, and
must not take its water from the cistern containing water for
dietetic uses.

The ventilating pipe must not be near bed-room windows,
water cisterns, under the slates, nor near skylights, house
ventilators, nor chimneys, because of the risk of in-currents,
and there must be a separate pipe for each closet.

“Safes” are required for closets on upper storeys, especially
if used for slops.

The walls of the water-closet should be of white glazed tiles;
it should be well lighted and have lofty windows ; the seat-hole
should be one inch less all round than the basin. Before using it
the handle should be pulled up, and the water allowed to run
for a little so as to wet the basin; and after use, the lid should
be shut down and the handle held up for a minute or so, then
let down to fill the basin, and then again lifted up for a little
so as to insure clearing of the trap and basin,

How is the Second Point best Carried Out ?

By means of a double trap and double ventilation.

The Trars—(1) A syphon one in the soil-pipe, and (2) the
valve at the bottom of the basin.

The Vuntiation —(1) Continue the soil-pipe, full size,
above the roof, as already explained; and (2) Carry a branch
15

into it from the space between the syphon trap of the soil-pipe
and the valve at the bottom of the water-closet basin.

Nors.—Housemaids’ sinks and waste-water pipes should
open over a grating two or three inches above the level of
the soil.

Name a Specially Bad Trap and Water-Closet.

The D-trap and the pan-closet: they are often together.
They tend to collect filth, and render the air very impure.

Norz.—(1) No cesspool for the detention or collection
of putrefying liquid refuse should exist within or under any
dwelling.

(2) No sewer should pass under any dwelling, if it can
possibly be avoided.

(3) All-water closet pipes should be doubly ventilated and
doubly trapped.

(4) All pipes from sinks, slop basins, lavatories, baths, etc.,
should be disconnected from sewers, and should discharge
through the outer wall of the house over the grated covering of
the disconnecting trap or gully.

Should the Surface Water be Admitted to the Sewers ?

This would depend on the rainfall: this is greater and more
frequent in the west as compared with the east part of a country.
Also, whether the surface was much inclined, or non-absorbent.
If the surface water be very great it should be excluded, but
a little may be admitted with advantage to flush the sewers.
It will also depend on the fate of the sewage ; if it has all to
be pumped up a certain height, then the surface water should not
be admitted. So also if it has to be cleansed by precipitation,
etc., the surface water would make it too dilute. Also, if it is
admitted, the great pressure might cause injury to the joints
16

of the sewer. It is more important especially to exclude the
surface water if the sewage is tide-locked for the greater part of
the day, or where pumping is only carried on at stated periods,
and where no reservoirs are provided during the night. In such
cases, if a heavy rain-fall is allowed to enter the sewers, all the
small pipes are filled up and flood basements and cellars and
low-lying parts of the town ; and, besides, if the joints are bad,
sewage escapes into the surrounding earth. The sewers being
filled with water, too, forces the air in the sewers up to the
highest parts of the town, and may force traps. It is in this
way that very often at fashionable sea-bathing towns the highest
parts of the town, where the best houses are situated, are
subjected to the uprising effluvia from the lowest parts. The
foulest portions of the surface water should be admitted to the
sewers, but the clean part should be sent into the river or
stream.

Should the Road Detritus be Admitted to Sewers ?

It is best to exclude it, because of the great expense of
removal of the mud; it also makes it more difficult to treat
chemically, and lessens its value as manure.

On what does the Quantity of Sewage Depend ?

1. The population.
2. Local and special trades—e.g., paper mills and gelatine
works require a very large amount of water.

3. Sewage proper—the water supply.

How much Organic Nitrogen in Liquid Refuse is Allowed to be
Poured into Rivers ?

Not more than ‘3 in 100,000 parts.
17
Give Examples where this is apt to be Exceeded.

Paper Mill Liquid contains, 76°816 parts
Woollen " 14:380 41
Blanket " " 19508 !
Flannel u" " 91°185 "

in 100,000.

What is the Difficulty in Purifying these Fluids ?

The extraordinary state of dilution ; the only way seems to
be if it could be purified by the land itself.

How does the Daily Discharge from Sewers Vary ?

One-half the daily outflow is discharged in four to six hours ;
the smallest quantity is discharged from 10 p.m. to 8 am.,
unless in mining districts where they work all night.

What Points have to be Considered in Fixing the Size of
Sewers ?

1. The maximum outflow.
2. The amount of subsoil water admitted.
3. The maximum amount of surface water to be admitted.

What are the Special Points in the Arrangements of Common
Sewers ?

1. All common sewers should be laid in straight lines,
whenever their sizes are not sufficient to allow the passage of a
man to remove deposits.

2. They should have true and even gradients from point to
point ; and where curves must be placed, then increase the fall
to compensate for the friction.

3. In the streets they should occupy the centre, so as to be

equally accessible from either side.
B
18

4, At the junctions of one common sewer with another, and
in the case of all small sewers, at every change of direction and
every change of gradient, there should be a shaft, or man-hole,
or lamp-hole, to be used for purposes of ventilation, flushing,
inspection, and the removal of obstructions. -

5. Where sewers are so big as to allow a man to walk in
them, they need not necessarily be straight.

What is a Man-Hole ?

It is a hole to let a man down to the sewer and up again.

Where should they be Placed ?

At the junction of one common sewer with another, or at
the concentration of several; at points where the angle of
direction is changed, so as to examine and cleanse without
breaking up the street. The bottom should be grooved so as
to allow the sewage to flow readily through.

What is a Lamp-Hole ?

It is a hole to let a lamp down.

For what Tpirpose 2

To enable a man at the next man-hole to see whether any
obstruction exists, which may then be removed by flushing,
or a jointed rod. The flow can also be watched through the
lamp-holes. Man-holes and lamp-holes are also used to ventilate
sewers; and if properly arranged, no gas gets into the houses,
and there is no excessive odour in the street.

How Often should they Occur ?
About every 100 yards—not Lzss than this.
19

What Special Points must be Attended to at Junctions ?

The tributary flow must be delivered at such a height and
in such a direction as not to interfere with the main flow;
if unequal sectional diameters, they should not be at the same
level, but the smaller should have a fall at least equal to the
difference of the sectional diameter. If it is not above the level
of the main, then the small side sewers will be back-watered,
and deposit takes place in the submerged part, so that it is
choked by its own silt. Pipes of equal diameter should not
be laid as tributaries—e.g., a 9-inch with a 9-inch, or a 6-inch
with a 6-inch, but a lesser should be joined on to a greater—
é.g., a 12-inch to a 15-inch, a 9-inch to a 12-inch, and a 6-inch
to a 9-inch, etc. In new sewers leave side junctions for house
drains, even though they are not required at the time.

How Deep should the Subsoil Drains be ?
Eight to ten feet.

How Far should the Common Sewer be from the Houses ?

It must be within 100 feet of every house included in the
sewage system, according to the “ Public Health Act.”

In Laying out the Sewage System of a Town, what should
Always be Done?

There should always be a map made of the whole sewage
system of the town.

What ts the Ultimate End of all Sewage ?

It must ultimately pass into the sea, a tidal river, estuary,
or inland river; the fall, therefore, must always incline in that
direction, but before reaching the final outflow it must be
purified from all foul and noxious matters,
20

Should the Sewage of Seaboard Towns be Discharged into the
Sea ?

That depends: it cannot, or should not, be discharged into
the sea—

1. If the sea is used for bathing or recreation.

2. If the town extends down to the water’s edge.

3. Unless the town stands well above the sea, so that the
outfall sewer may be carried far into the sea without converting
such sewer into a large sewage reservoir.

What is a Great Objection to Carrying Sewers into the Sea ?

The sewage is impounded in the sewer during the time the
tide is in, and this is bad, as there is great generation and
evolution of gases through gullies, etc., into the streets and
through traps into the houses.

How is the Evil Effect of this Evidenced ?

By the increased death-rate: in a healthy district the death
rate should be 17 per 1000 of the inhabitants: In Brighton
it is often 20, and in Liverpool often 27:5 per 1000, and that
too even though there are special shafts for ventilation. The
“cellar population” suffers very severely in such cases. It is
worse in cases where the sewers are not water-tight—e.g., at
Liverpool the sewage outflow is double the water supply, show-
ing that subsoil water must get into the sewer, and therefore
during the tide-locking sewage must get out and soak into the
soil, rendering it “excrement sodden.”

How ts this to be Corrected ?

The sewage should be raised and disposed of above the tide
. level; or it should be PuRIFIED—or at least clarified—before
it is discharged into the sea, and a constant outflow should be
secured independent of the tides. In all cases where the sewers
are tide-locked, there must be some special means of ventilation,
21

What Becomes of the Sewage Discharged into Tidal Rivers and
Estuaries ?

It is carried out to sea by the ebb tide; and it would be
better, therefore, if there was some temporary means of storing
it, so that it could be discharged only during the ebb tide.

What is the Disadvantage of this Method of Disposal ?

The banks become muddy, and in hot weather give off a very
great stench when the tide is out; and this is much intensified
when the mud is mixed with sewage. It is worse also in
summer, when the flow of the river is diminished.

What ts an Estuary ?

It is the expanded mouth of a river, forming an arm of the
sea, and extending inwards as far as the flow of the tide—
so called because of the BoILING appearance waoen the tide
flows up. A frith, or more commonly firth, is another name
for the same thing.

What Ought to be Done in such a Case ?

The sewage must be clarified, as well as purified, of all
putrescible matters, although the purification need not be carried
to so great an extent as if it were going to an inland river,
because the water will not be used for domestic purposes.

What Degree of Purity is Required ?

1. It should be free from offensive odour.
2. It should be perfectly clear to the eye.
3. It should be neither alkaline nor acid.

4, It should not contain more than 60 grains of solid
matters, when dried at 240° F.; and
22

5. Not more than -75 grains of organic and ammoniacal
nitrogen per gallon.

6. Not more than 2 grains of organic carbon per gallon.

7. And not less than 1 cubic foot of free oxygen per gallon.

But even with this degree of purity the water must not be
used for domestic purposes.

What is Necessary Before the Sewage of Inland Towns be
Discharged into Rivers ?

It must be purified from all foul and noxious matters by the
best known practicable means.

What Degree of Purity 1s Required ?
We should not admit to inland streams—

1. Any liquid containing in suspension more than three parts
by weight of dry mineral matters, or one part by weight of dry
organic matters, in 100,000 parts by weight of the liquid.

2. Not more than two parts by weight of organic carbon,
or ‘3 of organic nitrogen in 100,000 parts.

3. If one inch deep gives a colour against a white surface.

4. If there is more than two parts by weight of any metal
except calcium, magnesium, potassium, or sodium in 100,000
parts.

5. If more than 05 parts of metallic arsenic in any form in
100,000 parts.

6. If more than one part by weight of sulphur, either as
sulphuretted hydrogen or soluble sulphuret.

7. If more than one part by weight of chlorine, after acidi-
faction with sulphuric acid, in 100,000 parts.

8. If the acidity is greater than two parts of pure hydro:
chloric acid to 1000 parts by weight of distilled water.

9. If the alkalinity is greater than one part by weight of
dry caustic soda to 1000 parts of distilled water.
23
How can this Degree of Purity be Obtained ?

By using the soil itself as the purifier, either by—
1. Wide surface irrigation.

2. Intermittent downward filtration pure and simple, or partly
also by chemical means and then using the filtration.

In the case of villages and hamlets, it is easy to find land for
the purification of the sewage.

What is meant by an “ Intercepting Sewer” ?

It is used to mean two things :—

1. The principal sewers cutting off existing sewers which
discharge into a river at low level.

2. The sewer which divides the high ground from the low
and keeps that portion of the sewage of a town which may be
discharged by gravitation from reaching the lower parts of the
town—the sewage of which has to be pumped up to the proper
level or into the intercepting sewer.

Give an Example.

In London 274 square miles are intercepted on the north
of the Thames; lower than this, 254 square miles have to be
pumped up into the main sewer.

Where is Interception Important ?

In seaboard towns—e.g., Brighton—as much as possible
should be intercepted and pumped and discharged above the
tide. If the outfall sewer is made into a reservoir during the
night, take care that is it not overcharged, and provide proper
ventilation.
24
What Velocity is Required to make Sewers Self-Cleaning ?

It depends on the nature of the sewage—

60 feet per minute is enough for clear sewage.
90 feet per minute is required for strained sewage.
150 feet per minute is required for ordinary sewage.

Large sewers require 176 feet per minute when three-
fourths full; 165 feet when one-half full; and 146 feet, when
one-third full.

30 feet per minute will not disturb clay or stones.
40 feet per minute will move along coarse sand.
60 feet per minute will move along fine gravel.
120 feet per minute will move along road pebbles.
180 feet per minute will move along angular stones about
a inch and three-quarters in diameter.

What is the Bottom Velocity of a Sewer ?
It is four-fifths of the mean velocity.

When do we get the Greatest Discharge from a Sewer ?

We get the greatest discharge from a circular conduit when
it is fifteen-sixteenths full.

And the Greatest Velocity ?

The greatest velocity is secured by keeping it thirteen-
sixteenths full.

What Fall should Sewers Have ?

A two-feet sewer, with cLEAR sewage and a velocity of 60 feet
per minute, requires a fall of 1 foot per mile or more.

If strained sewage be carried at a velocity of 90 feet per
minute, it requires a fall of 24 feet per mile,
25

Ordinary sewage, at a velocity of 150 feet per minute, will
require a fall of 74 feet per mile.

This shows the value of screening sewage, in cases of slight
fall.

How would you Calculate the Discharge from a Circular Sewer ?
Find the velocity in feet per minute thus—

V=55 VRx2H
R =hydraulic mean depth.
Hi = Fall in feet per mile.
V = Velocity in feet per minute.

Multiply the result of the sectional area of the pipe and

this will give the cubic feet per minute and one cubic foot
is = 6°25 gallons.

What ts the Hydraulic Mean Depth ?

It is the sectional area divided by the wetted perimeter: in
circular sewers it is always HaLF the actual depth.

How do you Find the Sectional Area ?
Square the diameter, and multiply by ‘7854.

What are the Advantages of Egg-shaped Sewers ?

The egg-shaped are better than the circular when the flow
varies from a small minimum to a large maximum. With the
small quantity the small end of the sewer scours better, and
the great size of the upper part affords space for the increasing
outflow. If the minimum flow be one-half the maximum, so
that the conduit is never less than half-full, there is no
advantage derived from the use of the egg-shaped sewer, but
rather disadvantage, for the circular are cheaper to construct and
of greater strength.
26
What are the Forms of Egg-Shaped or Oval Sewers ?

Tue Orp Foru—
Vertical diameter = 14 times the transverse.

Radius of inverts = 4 the transverse diameter.
Radius of sides = 14 times the transverse diameter.

Tue New Foru—
Vertical diameter = 14 times the transverse.
Radius of invers; = 4 the transverse diameter.
Radius of sides = 14 times the transverse diameter.

What Materials are Used in Sewer Construction ?

1. Bricks laid in cement or hydraulic mortar.
2. Stoneware pipes.

3. Concrete alone, or with bricks and pipes.
4, Iron pipes.

Under what Circumstances is Iron to be Preferred ?

At river crossings, and at sewer deflections, as in crossing
from one side of a valley to another, in passing through unsound
ground, and sometimes through closely inhabited districts.

How should Sewer Joints be Made ?

With tarred gaskin well caulked in, and finished off with
cement.

Is Puddled Clay Good ?

No; it is apt to swell and contract alternately, and crack
. when dry, and apt to be forced out, and roots of trees can easily
make their way into the pipes. The clay joints are almost sure
to be leaky.
27 se be

4
pb

What is Good Cement ? 2 eat er

Portland cement of 110 to 112 Ibs. to the striked riche,
and used in the proportion of one of cement to one of clean
washed sand. Roman cement sets more quickly. Cement must
be properly mixed and used aT ONCE.

What Kind of Bricks should be Used ?

The inner layer must be smooth, and all must be well
burned and well shaped. Examples—London stock, Gault brick,
blue Staffordshire, or fire-clay glazed on one side.

What Thickness of Stoneware Pipes should be Used ?

Well formed and well burned, and a thickness of not less
than one-twelfth internal diameter; and in small sizes the thick-
ness must be increased—eg., a 4-inch should be half-an-inch
thick, and an 18-inch about an inch and a half only.

How Deep should the Joint Socket be ?

An inch and a half in the smaller sizes, and two inches or
more in the larger.

What are the Use of Gullies ?

These are best with deep catchpits to catch the surface water
from the streets, etc., and retain the road detritus, but let the
water pass into the drain or sewer, as it is cheaper to remove
the road detritus and mud from the gully than at the end
of the sewer. It must be trapped to prevent the escape of sewer
gas.

What is a “ Storm Overflow” ?

It is an arrangement to act as a safety valve, connected with
the intercepting or outfall sewer which it may cross at right
28

angles; the opening into the sewer is so arranged that up toa
certain point the storm overflow drops the whole of its contents
into the sewer, but all excess is carried forward by its own
velocity and inertia past the opening and emptied by the storm
overflow into the river.

What is Necessary when the Sewer Ends in the Sea or a Tidal
River ?

A self-acting valve or flap at the end of the sewer, when it
opens into the sea or a tidal river below high-water mark level,
to prevent inflow of sea and keep out the wind which would
drive back the gases. It must be truly balanced and self-acting
and yield to the slightest pressure, close-fitting and face the sea,
and protected so that the waters do not act upon it directly,
making it move backwards and forwards, thus wearing it out.
If some such plan is not adopted the low dwellings and cellars
are apt to be flooded, as the sea will pass into the sewer, as at
Liverpool and Ipswich.

What are the Objections to Charcoal Baskets for Sewer
Ventilation ?

It is apt to be mixed with dust and become damp and lose
its power unless very frequently changed : if too closely packed
it impedes ventilation and when too loose and damp itis no

good: when too closely packed it stops the outflow of impure
air.

What are the Best Means of Ventilating ?

It is best to trust to a sufficient number of man-holes, lamp-
holes, and shafts, assisted by light flaps in man-holes and double
ventilation, as already explained, of the house drain opening
into the common sewer, by shafts or pipes carried up above the
29

level of the houses. ‘Free circulation of the air in the sewers
and incessant movement of the liquid are the best preventives
of the generation and carriage of injurious products by means
of the sewer gas—e.g., typhoid stools agitated in the presence
of fresh air undergo chemical change without generating any
injurious products; but in badly constructed and ill-ventilated
sewers the specific poison is rapidly reproduced and disseminated,
and the gases convey the infection, and as they are very light
they diffuse rapidly and seek the highest points—+.e., the house
drains and soil pipes of the houses in the highest parts of the
town, and usually, therefore, of the rich and well-to-do; and
hence the reason why typhoid fever is rather a disease of the
tich than the poor, and more especially is it due to the
pernicious habit of having a private water-closet in or opening
directly into the private bedrooms. This plan no doubt is
very convenient, but is very nasty and dangerous. The same
remarks also apply to wash-hand basins fixed in one corner of a
bed-room.

What are the Eifects of Pouring Hot Water into the Sewer ?

It is extremely bad and dangerous in unventilated sewers,
as the hot water makes the air expand and forces traps; but
if well ventilated, with free circulation of air, it does little or
no harm.

What Effect has the Changing Volume of Water ?

As the water rises the space is reduced, and hence the gases
are under great pressure and may be forced out through traps,
etc. ; and then when the water falls a tendency to a vacuum is
produced, and as air must be got the traps are forced in in the
‘opposite direction and left unsealed. Between morning and
noon is the time when hot water passes in usually, and also the
time of increased flow and therefore lessened air space; from
30

this time there is a gradual fall till next morning. The great
importance, therefore, of having free ventilation in the sewers
will be at once evident—

1. To get rid of foul gases.

2. To prevent their generation.

3. To let out the air, when the space is lessened by
hot water or increased flow.

4, To let in fresh air, when the space is increased
and the water cold.

What is the Amount of Feces and Urine voided by a Population
of 1000 Persons ?

Daily—
Feces, 156 lbs.
Urine, 250 gallons.

Yearly—
Feces, 25 tons.
Urine, 91,250 gallons.

What are the Objections to the old-fashioned Midden and Privy ?

They spread filth diseases—cholera, enteric fever, and
diarrhoeal complaints: they pollute wells, and soak into the
soil round about and pollute the air; the materials also decom-
pose, and this lessens their agricultural value. Leaky sewers
are almost as bad.

How may the Bad Effects be Lessened ?

In villages, if they must be used, they should be water-tight,
and small, so that they must be frequently cleared out. So
privies also; and if the receptacles are moveable, they are not
so bad if they are properly looked after.

What is the “ Pail” System ?

' Where the excreta are caught in pails or shallow tubs con-
taining some absorbent material or deodoriser, and often and
31

regularly removed by the Sanitary Authority of the place. The
pails usually contain crude chloride of aluminium or copper
sulphate ; they are then emptied into a trench formed of fine
ashes, with 30 lbs. of sulphuric acid to the ton, and the whole
well mixed. In three days it is turned over with a spade, and
again in twenty-one days, and after this it is pretty dry; it is
then screened and sold as manure.

Where ts this Plan Adopted ?
In Rochdale.

What is the “ Goux” System ?

It is a special form of the pail system. A shallow tub or
pail is lined with stable litter, loft sweepings, shoddy, sawdust,
spent tan or hops, mixed with soot, charcoal, crude ferrous
sulphate or gypsum. A layer 4 inches thick is first laid in the
bottom ; then on this a mould, 6 inches less all round than the
tub or pail, and then the material packed into the space at the
side all round and the mould removed leaving a hole. The tubs
are 164 inches high and 20 inches wide at the top. The
prepared pails are distributed to the houses, and the others
removed every two days: it is necessary that the Sanitary
Authority should look after them.

Where ts this Plan Used ?

It is used in Halifax. It is also good for Collieries.

What is Moule’s System ?

It is one form of the dry-closet system, dry earth is made
use of to cover and deoderise the excreta. It consists of a
wooden box, with a pail beneath, a reservoir for the earth above
and an apparatus for measuring and delivering the proper ,
quantity of earth every time the closet is used ; the earth must
be dry and loose.
32

How much Earth is Required ?

About 1} Ibs. for each stool, inclusive of the urine passed
with the stool: the rest of the urine, and the slops, etc., must
flow away by some other channel. If the urine too is to be
caught, then it will require 4 lbs. of earth every time the closet
is used.

For what is this Specially Suitable ?

Public establishments, private estates, and villages: it is
not suited for large towns. In Sir A. de Rothschild’s estate,
Moule’s closets are used, and they are all looked after by one
man. For villages, where the earth is easily got, it is very good;
and in country houses the earth may be dried and used again.
Charcoal could be used, and then it would only need one-fourth
the quantity ; but itis too dear and difficult to get.

What Forms of Earth are Best ?

1. Rich garden surface mould is the best.
Peaty soils.

. Black cotton soils.

. Clays.

. Stiff clayey loams.

. Red ferruginous loams.

. Sandy loams.

8. Sand and gravel—the worst of all, and almost useless:
chalk is also of very little use.

NI Oo BR oo BD

What are the Objections to Moule’s System ?

1. The trouble of providing a sufficient quantity of dry earth
of the proper kind—at least 14 Ibs for each dejection ; and for
urine and all, 4 lbs. are required.

2. The expense of cartage in bringing the earth into the
town and removing it again.

weel
33

3. It is offensive to the sight.

4. Difficulty of securing proper attention to the working |
of the closets.

5. Small value of the resulting manure—£2 to £3 per ton.

6. The excreta are retained in the neighbourhood of the
houses.

What are the Advantages of the System ?

1. It is cheaper in the original cost than water-closets.

2. It requires less repair.

3. It is not injured by frost.

4. It is not damaged by improper substances being thrown
down it.

5. It reduces the amount of water required by each
household.

Special means must be provided for the removal of slops,
rain water, and soil water.

Name a Modification of this System.

Morrelle’s plan of using riddled cinders, such as can always
be got from ordinary coal fires; the result, like the last, is then
worked up into manure.

Where is this Plan Used ?
In Salford and Manchester.

All such closets must be managed by the Sanitary Authorities
of the place, and not be left to individual preference. Ash-pits
and dust-bins must also be carefully attended to; they should
be protected from the sun and rain, well ventilated and small
in size, water-tight, and be very frequently cleaned out. All
cess-pits must also be perfectly water-tight, if they are to be
used at all, and even then all wells used for domestic purposes
must be at least 100 feet from any such cess-pit or sewer.

Gg
34
What is the Best Means for the Disposal of Liquid Sewage ?

By using the land itself ; dry earth is a good deodoriser, and
a good purifier if it be passed through it intermittently, so as to
allow it time to be erated and oxidised. The growth too of
grasses and vegetables gives a good return for the primary outlay
and working, and the land steadily increases in value from year
to year; of course the amount of profit will depend a good deal
on the demand for succulent grasses and vegetables.

Give Examples of this Method. ©
The cat. See also Deut. chap. xxiii. 5-13.

What is the Theoretical Manurial Vulue of the Excretu ?

An adult gives off in excreta 16°41 lbs. of nitrogen yearly,
which is sufficient to yield 800 lbs. of wheat or 900 lbs.
of barley. Liebig says that one can give enough nitrogen
for sufficient manurial matter to raise from an acre of ground
the richest possible crop every year. Besides the combined
nitrogen—which is the measure of the manurial value—we
have phosphates, which are also very valuable.

What is the Actual Monetary Value ?

This is measured by the combined nitrogen. About 124 lbs.
of ammonia is produced per head every year; this is worth
about eightpence or ninepence per lb. About 54 lbs. of
phosphates are produced per head per year; worth about
twopence per Ib. So that the actual monetary value of the
feces and urine of England and Wales alone is equal to
£5,000,000 every year.

The urine is about six times as valuable as the feces from
_a@manurial point of view. Chemical processes for the disposal
of sewage are about from four to six times more expensive to
the ratepayers than by using the land itself.
35
What are the Drawbacks to Sewage Farming ?

1. The outflow of sewage is constant, and must be disposed
of without nuisance, night and day, Sunday and Saturday, all
the year round.

2. The special character of the produce growing therefrom.

3. The farm requires a large amount of labour, and a large
outlay of money.

4, The home market for the prodded is limited ; and

5. If transported to distant markets will not pay, and the
larger the area of soil utilised the greater the loss.

What Crops are Best Fitted for Sewage Farms?

Fast growing succulent grasses, and market garden vege-
‘ tables —e.g., Italian ryegrass, mangolds, swedes, carrots, parsnips,
cabbages, potatoes, and onions.

What are the Solid Matters of Sewage ?

1. Bulky substances that can be removed by screening, as
corks, sticks, dead cats, etc.

2. Substances that quickly sink of their own weight, as road
detritus.

3. Very fine substances which are not deposited when the
sewage is in motion, except by adding chemical precipitants ;
when left at rest, it is deposited slowly, and this = “sludge.”

What are the Chief Precipitation Methods ?

1. By adding lime, 12 grains to the gallon stirring it and
then allowing it to settle; by this plan the ammonia is lost and
the solid matters are left in the water.

2, By adding the coarse salts of iron or aluminium, with or
without lime.

3. Phosphoric acid.

4, The A BC process—alum, blood, and clay and char-
coal, or crude aluminium sulphate.
36

i
Describe the A B CO Process.

When the aluminium sulphate or alum is added, the
alkaline liquid decomposes it and forms the hydrate of
aluminium, and this attacks the nitrogenous matters, but is very
light, and therefore, the clay is added to make it sink. The
‘carbon is to absorb and decompose foul gases, Lastly, a little
sulphuric acid is added to the mud to fix the free ammonia, and
then whole dried in hot revolving cylinders. ,

This plan is used at Leeds.

What is the Phosphate of Aluminium Process ?

Phosphate of aluminium and calcium is added to the sewage.
The aluminium curdles and coagulates the fecal matters; the
calcium draws the soluble phosphates from the sewage and
forms a precipitate, and this carries down the coagulated fecal
matters. It is then left in tanks to settle and the clear water
allowed to flow off, while the solids are dried. The water is not
fit for rivers.

Where is this Used, and what Becomes of the Effluent Water?

It is used at Hertford, and although the water is so filthy as
not to be fit for rivers used as domestic supplies, it is allowed to
flow into the Thames apove the intakes of the Water Companies
‘that supply London; but perhaps this is good enough for the
inhabitants of “the common sink of Paris and of Rome.”

What is the Sulphate of Aluminium Process ?

This is a plan introduced by Dr Anderson of Coventry. . The
crude sulphate is prepared from clay by adding sulphuric acid—
two pints of clay and one of acid. This is mixed well and
placed in a warm place to dry, and then it is added to the
sewage in a tank in the proportion of 1 1b. to the 100 gallons,
or 4 tons to the million gallons. To this is added common
lime, the aluminium hydrate is set free, and sulphate of calcium
is formed; the precipitates fall to the bottom and carry the
37

sewage with them. Now it is in the hands of a Company,
who—

1. Strain off the solids, to be used in orchards.

2. Then treat it chemically, as above.

3. The effluent water is filtered intermittently through the
soil, which is then cropped with ryegrass and osiers.

4, The sludge is dried and sold at about 35 to 40 shillings
per ton; and by fortifying it by chemical fertilisers it will
become worth from £5 to £6 per ton ; but even then the process
is not self-supporting.

What is the ‘‘ Scott Sewage Company ?”

It is burning the combustible parts of the sludge in the
manufacture of cement and limes. Slaked lime is added to the
sewage, and this causes a precipitate of the carbonates, phos-
phates, and silicates ; then clay is added to combine with the
silica and the alumnia: the precipitate is removed from the
tank and dried and then burned in kilns—once it is begun its
own organic matters are enough for fuel to burn it. The result
is then ground to a fine powder, the product being two tons
of Portland cement from one million gallons of sewage.

What is Liernur’s System ?

It is the “pneumatic” system. The town is divided into
districts of from 200 to 1000 houses, and each district centres
in an air-tight iron tank about 3 feet below the surface. This
tank is connected with the closets of the houses by air-tight
pipes. In the centre of the town is placed a central station,
with air-tight reservoirs and engines for pumping out the air:
the station is connected with each district tank by a separate
system of air-tight pipes. The pipes and tanks are exhausted
by the engines, so that the excreta is drawn or rather forced to
the central station by the atmospheric pressure: at the central
station the excreta is converted into a dry powder by means
of the exhaust steam.
38
Where is this Plan Used ?

In towns in Holland, Prague, Olmutz, and St Petersburg.

What are its Advantages ?

1. The pipes are emptied daily.
2. They are all 5-inch cast-iron pipes, with lead and tow
joints.

3. Should a hole exist in the pipes, the pressure is inward,
and matters would be “sucked in” and close it up.

4, There are no valves, only cocks that can be easily
examined.

5. Closets are without water, are funnel-shaped, and ven-
tilated from the funnel, and another ventilating shaft from the
soil-pipe.

6. Pipes cannot stop up by improper substances being thrown
down.

Means must be provided for removing sink refuse and liquid
refuse of trade by another set of pipes; so also the rain and
subsoil water.

The influence on health is good; there is no pollution of
air, water, or soil ; and typhoid fever, diphtheritic sore throats,
and cholera are banished.

What is Webster's Method ?

Treating the sewage by means of electricity ; the current is
passed through the sewage in the tank: in this way gases are
formed that carry the solid matters to the top. The fluid is
then agitated, the gases pass off, and the solid parts settle to the
bottom without any tendency to diffuse through the fluid again.

When should these various Artificial Methods be Used ?

Only when land cannot be obtained for the disposal of
sewage. Frost is no bar to its disposal by land, as the average
temperature of the sewage is higher than the outside air, so that
39
it will thaw the frozen land—the temperature in the sewers being
higher especially in winter and autumn. The land purifies the
sewage and the sewage fertilises the land; the soil filters, and

then the oxygen in the earth and vegetations on the soil destroy
it by chemical and vital action.

What is “* Wide Surface Irrigation” ?

It is a method for the disposal of sewage by using the soil
itself—e.g., irrigated meadows, as at Edinburgh. The sewage is
spread over a wide surface without precise regard to its REGULAR
absorption and infiltration. It is not or should not be flooded,
but such a quantity used as will satisfy vegetation without
waste, and the absorptive powers of the soil without overflow.
The land, too, ought to be under-drained at about the depth
of 6 feet from the surface, as this will remove the purified water
and also erate the soil, which is of great importance ; otherwise
it is apt to become a huge morass or swamp, and the oxidative
powers of the soil are impeded if not destroyed.

What is the Best Site for a Sewage Farm?

All sewage farms should be laid out on slopes; it must not
be too flat or too steep, and the land must not be too retentive
or too porous.

How much Land is Required ?

An acre for every 100 persons of prospective population.

What Crops are Best ?
Usually Italian ryegrass.

Name Suitable and Unsuitable Sorts.

SurraBLe—a soil naturally fertile gives the best and quickest
returns: the Best is loam, with a small proportion of gritty
gravel to allow of percolation,
40

The worst soils are stiff clays, coarse gravels, and boggy peat
lands; the clay cracks, and the raw sewage runs into the cracks
and fills them up. Still, if well under-drained and prepared,
clay might do, as at Harrowgate and Earlswood. But if such
land is undrained, the sewage often runs off as bad and filthy as
it was run on. If the soil be too free, it is also bad, as it runs
through it too quickly—e.g., Heathcote Farm, Leamington,
where each acre receives from 10,000 to 15,000 tons.

The best soil then for wide surface irrigation is a fairly free
soil, with a small proportion of clay to moderate its percolative
powers.

How much Should each Acre Receive ?

Fifty tons is enough to fertilise a growing crop.

What Depth is that over the Whole ?

Half-an-inch deep over an acre is = 50 tons, and 1 inch
is = 100 tons (or 101 tons, less 2 gallons)—#.e., 1 inch deep
over an acre is = 22,622 gallons, and 1 ton of water is = 224
gallons, and 1 gallon = 10 lbs.

What is the Use of Under-Draining ?

To prevent wetness, and allow the soil to be properly erated.

How Many should there be?

That depends: if the soil be free, then only few drains;
if retentive, many are required; and in clay soils they must be
as numerous as possible. The sewage must not be allowed to
travel directly over them.

What Surface Preparation is Required ?

Means to secure an even distribution of the sewage; it
should be in slopes—free soils requiring a gradient of 1 in 20
or 25, or less might do: depends on the nature of the soil.
41

Also require DELIVERING conDuits from the outfall sewer, with
TANKS sometimes, to separate the coarser parts of the sewage ;
and sLuIce cHAmBERs, to direct it at various points from the
delivering conduits into the DIsTRIBUTING CARRIERS, which are
formed by the ground itself: in these carriers there must be
stops of metal or wood, to direct the flow and supply all parts
of the soil evenly.

What are the Different Modes of Distributing the Sewage ?

1. The ‘“catch-water” system.
2. The “pane and gutter” system.
3. The “bed” system.

What is the “ Catch-Water” System ?

There is a series of carriers following the contour lines of the
ground, one under the other, with just sufficient fall to carry
the sewage forwards; by the help of stops, they distribute the
sewage over the land, and also “catch” the water that flows off
from the part above and so on, and this water may pass over
several. Even at the last it is not all absorbed, and some may
find its way into the stream uncleansed. This plan is well
suited in cases where Italian ryegrass is chiefly grown; but
with stiff clayey land, and in wet weather, it may flow off
very impure.

What is the “ Pane and Gutter” System ?

The ground is divided into wide beds, with but little fall,
and is fed from the top by gutters traversing its surface, with
panes so as to allow of even distribution. In this plan there is
‘often a good deal of waste, where the beds are large; and if
uneven, the sewage collects in pools, evaporates and leaves the
sludge, and creates a nuisance. Very often, too, large quantities
are used by this method—e.g., 15,000 to 20,000 tons per acre,
which is far too much.
42
What is the “ Bed” System ?

The land is formed into ridges and furrows in parallel
straight lines, with carriers or gutters along the ridges, with
stops at the sides to let the sewage out: the width of the
“beds” is from 30 to 150 feet, and the slope of the surface
from 1 in 25 to 1 in 150.

Describe another and Better Plan of Sewage Distribution.

It is better that the sewage should not pass over the surFacE
at all, but should pass down furrows between NaRRow ridges
formed by the hand or a double mould board plough. Crops are
grown on the ridges, and the space between is just sufficient to
separate the rows of plants from each other, and the sewage
soaks in close to the roots of the plants. When the crops are
removed the narrower ridges are split up by the double mould
plough, and the whole field laid out flat for the growth of other
crops, as wheat, oats, pulse, etc. The narrow ridges of course
are no good for the growth of ryegrass, but are specially fitted
for the growth of roots and vegetables.

Where is this Plan Used ?

On the plains of Genevilliers, near Paris. The green parts
of the plants never touch the sewage at all, the fertilising liquid
reaching the roots laterally.

' What is “ Intermittent Downward Filtration” ?

The land is divided into four equal parts, and each part is to
receive the whole sewage for six hours out of the twenty-four.

By this plan water-closet towns of 10,000 could be cleansed
on five acres, provided the ground be well under-drained to
a depth of 6 feet.

In this way the land is like an immense lung, filtering and
oxidising, alternately receiving and expiring air; each part rests
43

eighteen hours out of the twenty-four, and in doing so drains
itself and becomes refilled with air. By this plan a cubic yard
will cleanse 44 to 10 gallons in twenty-four hours,

What are the Objections Urged against this Plan ?

Dr Frankland, who first suggested the method, gives the
following objections—

1. There is no profit.

2. The manure is all lost.

3. The solids collect on the surface, and cause a nuisance in
hot weather.

Who is the Great Apostle of this Method now ?
Mr Bailey Denton.

Name a Place where it is Used ?
At Merthyr Tydvil.

How is it Conducted there ?

1. Three areas instead of one are in constant use, each being ©
capable of cleansing the whole sewage.

2. The areas are divided into ridges and furrows, and the
sewage is run into the furrows for one year at a time, and then
each remains free from sewage for two years in succession, and
devoted to plant growth.

3. On the areas actually in use, crops of succulent vegetables
are grown.

4, The area in use is so divided that one-third or one-fourth
of the sewage shall be applied to it for a fixed period each day,
so that there is a daily intermittency as well as a tri-yearly.
The ground is well under-drained 6 feet down.

How much Land is Required for this Plan ?
One acre for every 1000 or 1100 of the inhabitants.
44

Compare “ Wide Irrigation” with “Intermittent Downward
Filtration.”

Wine Irrigation means the distribution of sewage over as
many acres as it will wet, without super-saturation, having in
view a maximum growth of vegetables for the amount of sewage
applied.

INTERMITTENT DOWNWARD FitTration is the concentration of
sewage at short intervals, on as few acres of land as will absorb
and cleanse it, without excluding the production of vegetables
at the same time.

Should Clay Soil be Used ?

Not if possible, and if it must be used then it should be
trenched for 2 or 3 feet down and mixed with cinder ashes,
chalk, sand, or gravel.

What about the Under-Drainage ?

If in free soil, they should be deep and few—the deeper they
are the more perfect the filtration ; they should be under the
banks and barrow paths, and not directly under the furrows,
and 6 or 7 feet down; hence under every square yard there are
2 cubic yards of filtering material = 9680 cubic yards per acre.

How Much will an Acre Cleanse ?

Every cubic yard cleanses from 4 to 12-4 gallons per day, so
that a single acre will cleanse from 40,000 up to 124,000 gallons
per day.

What Surface Preparation is Required ?

It should be made roughly level, so that the sewage may be
applied evenly and divided into ridges, with furrows between.
The width of these will depend on the nature of the soil; the
more level the better for intermittent downward filtration. It
is well to have ventilating shafts at the junctions of the drains,
so that we may see how far the subsoil water rises, and it also
helps eration.
45

Are Sewage Farms a Cause of Ill-Health ?

No, they are not a cause of ill-health—e.g., Piershill Barracks,
near Edinburgh, Barking, Croydon (Beddington), and Norwood,
where the death-rate actually fell. Restalrig, near Edinburgh,
is surrounded by the irrigated meadows, and Regent Terrace
and Carlton Terrace are pretty near; but the barracks (men),
Restalrig (old people mostly), and Marionville (children) are
all healthy. The sewage farms are no cause of the spread of
entozoa (Cobbold)—e.g., in oxen fed for two years on the grass.
The cows in Edinburgh, too, are fed on the grass from the
irrigated meadows, and yet there is no word of any increase in
the frequency of cases of tape-worm.

Give a Résumé of the various Plans for Dealing with Sewage.

1. In small rising towns, may use the “double system” of
sewers: the sewage is not diluted, and can more easily be
used up, while the rest of the foul water can be returned
to the river.

2. Passing the sewage into rivers—very bad.

3. Liernur’s system (pneumatic).

4. Precipitation methods—

(1) By lime.

(2) Coarse salts of iron and aluminium.

(3) Phosphoric acid and phosphates.

(4) The A BC process.

5. Using the soil itselfi—the best of all.

(1) Irrigated meadows—wide surface irrigation.

(2) Intermittent downward filtration. Any of the four
elements of the ancients may be used—fire, earth
air, and water. Water carriage is the best.

What are the Objects of Sewers ?

1. To drain the surface.
2. To drain the subsoil. (1) -
3. To remove feecal and liquid refuse,
46

Notz.—Before 1815 it was illegal to allow sewage to pass:
into rivers: in 1847 an Act was passed to compel the passage
of sewage into rivers ; and at the present day it is not lawful to
pass sewage into rivers until it is purified by the best practicable
and available means.

What Points have to be Considered in Sewering a District ?

Consider—

1. The area of the district to be sewered.

2. The rainfall, and the proportion to be admitted into the
sewers. ;

3. The geological character and the physical outline of the
district.

4, The present and prospective population.

5. The water supply.

6. The sanitary appliances to be adopted.

7. The position of the outfall, and the mode of disposal of
the sewage to be adopted.

What Authority is Required ?

The Local Government Board, by provisional orders, when
sanctioned by Act of Parliament, can compel the execution of
sanitary works. If the works extend into the sea way, then we
must gain the assent of the Admiralty.

What ts the Fault of must Sanitary Laws ?

They are too permissive: it is “may” do so and so, instead
of “ sHALL” do so and so,

What are the Results of Sanitary Works?

1. Lessened death-rate.

2. Improved health and physical ability.

3. Natural prosperity.

4, Increase of health, which is capital, and less sickness.
47
What are the Three Chief Things ?

"1, Pure air, and plenty of it.
2. Pure water, and plenty of it.
3. Rigid cleanliness of person and house.

Are Beetles of Use?

Yes; they are often excellent scavengers.

Should the Rain-fall be Admitted to the Sewers ?

Small rainfalls give very foul water, and should be admitted ;
large, give pure water, and probably should be excluded. For
this purpose have a ‘‘storm overflow,” so that the water when
the velocity is great is shot past the opening into the sewer, but
when the velocity is low then it falls into the sewer. The water
spouting from an orifice forms a parabola, and when the velocity
is great the space‘fallen through is small, and when the velocity
is small the space fallen through is great, as it is longer exposed
to the influence of gravity. The rain is a scavenger of streets,
courts, yards, and roofs ; and when small is as foul as sewage.

What are the Oljections to Admitting the Rain Water ?

1, When the sewage has to be pumped it dilutes it too
much.

2. If the sewage has to be treated chemically, it is better to
exclude it.

3. Also probably in towns with tide-locked sewers, it should
be excluded.

Storm and spate waters should be excluded, as they might
burst the sewer, or, if made large enough to accommodate the
spate and storm waters, then in dry times the sewers would be
far too large and deposit sludge. If surface water pollutes
rivers, the Sanitary Authority is liable for the results. Much
of the rain water is absorbed into the soil and a good deal
of it evaporates from the surface, so that it is only a certain
48

percentage that will enter the sewers. In gravelly and chalky
soils it is almost all absorbed; if the district be steep, much
runs off and finds its way to the sewers, and little is absorbed.

What is the Objection to Too Steep Gradients in Laying Out
Sewers ?
If the gradients are steep the sewers act like chimneys,
drawing off the foul gases from the lower parts and dispersing
it to the higher parts.

How would you Estimate the Prospective Population ?

Get the increase for some years back, and calculate forwards — .

in the same ratio, or a little more. In manufacturing districts,
near large centres of population, the rate of increase is much
faster.

Do Water-Closets Increase the Amount of Sewage ?

The great consumption of water is due to the imperfect
. fittings ; the water-closets themselves do not materially increase
the water supply, nor increase the volume of sewage of the
towns. The sewage of midden towns is almost as great as in
water-closet towns; there is more chlorine in a given volume
in midden towns.

What ts a Sewer of Deposit ?

The old sewers were sewers of deposit, and very soon pean
choked up, and had to be made large enough to let a man in to
clean them out.

How was this?

It was due to faults in size, form, mode of construction, and
materials. The inverts were flat, the walls rough, corners
numerous, the flow was small and the velocity slow, the joints
were leaky, and for all these reasons the sewage was deposited.
These conditions must be reversed in order to secure “self-
cleansing sewers.”

 
49

What Velocity should be Allowed ?

In no case less than 2 feet per second, and usually much
greater: house drains should be 44 feet per second. Pipes of
6 to 9 inches in diameter need a velocity of 3 feet per second ;
pipes of 12 to 24 inches need 24 feet per second—the smaller
the sewer the greater the fall.

How much Fall should be Allowed ?

A 10-feet sewer needs a fall of 2 feet per mile.
A 5-feet sewer, 4 feet per mile.
A 2-feet sewer, 10 feet per mile.
A 1-foot sewer, 20 feet per mile.
If a sewer is not self-cleansing, it must be flushed occasionally.

What is the Cause of Motion in Sewers ?

Gravity is the sole cause of motion. The resistance is caused
by the bed and sides of the sewer: the nature of the materials
make little difference, because in every case it becomes covered
by a thin film of water, so that the friction is between two
layers of water.

* What is the “ Wetted Perimeter 2”
The part of the pipe touched or wetted by the water.

How is the Resistance Measured ?
It is inversely as the section of the pipe, and directly as the
velocity.

What is the Hydraulic Mean Depth in a Circular Sewer ?
When it is full or half-full it is always one-fourth the
diameter of the pipe or tube.

Should Sewers be Laid at the Back of Houses?
No, not as a rule, It is more economical to the Local

Authority, and safer, to place the public sewers in public
D
50

thoroughfares than in private land at the back of houses. If
laid in the back yards, they could. not be in straight lines, and
the manholes, ete., would interfere with the rights of private
property ; besides, the Local Authority has no right to enter
private property except by purchase. The objection to the
street has arisen from the fact that house drains have often
had to be carried through or under houses, but this is only true
when they are badly constructed and arranged. Sometimes it
is necessary owing to the outline of the district—e.g., Princes
Street, Edinburgh.

When are Intercepting Sewers Necessary or Advantageous ?

Often necessary to make the works pay. When the district
has a small longitudinal fall, but no lateral fall. May be necessary
for the safety of large districts, as the volume of sewage or rain
water can better be brought under control, than when the
district is large and all is allowed to fall to the lowest level.

Also in sea-coast towns, where the lower sewers are tide-
locked.

Can also be used in districts that overgrow existing sewers.

What Conditions ought a Sewer to Fulfil?

It ought to convey the sewage with maximum velocity, both
minimum and maximum flows, and be strong enough to resist
the weight of earth above and at the sides. The circular form
is the cheapest and strongest, and should be used where the
flow is uniform. ,

Should Gas Pipes be Laid in the same Drains with Sewage
Pipes?

It is better not. In Paris both gas and water pipes are
placed in the subway of the sewer; but the gas pipes are
dangerous from the risk of leaks, and then explosions occur
when a light is carried in by the workmen,
D1
What is a “ Small” Sewer ?

Eighteen inches in diameter and under: these are best
constructed in earthenware or concrete, and made circular.

What Size should be Adopted ?

No pusiic sewer should be less than 9 inches in diameter,
because if less it is very apt to be choked up: the number
of blocks or stoppages are greatest in the small ones, and least
of all in the 9-inch sewers.

Of what Materials should the Pipes be Made ?

Fire-clay or stoneware; of which, the latter is the better
material of the two. They should be impervious, uniform in
thickness, tough and strong, true in section and_ perfectly
straight, glazed inside and outside, and free from cracks of all
kinds, and should give a clear ring when struck.

What its the Best Glaze to Use?

Salt glaze is the best, because it goes through the whole
thickness of the pipe; whereas lead and glass glaze merely
varnish the surface.

Why should they be Impervious ?

To prevent—
1. The entrance and crystallisation of water in times of frost.
2. The formation of crystals in the interior in presence of
certain chemical compounds.
3. The direct chemical action of materials found in the
sewers,

How would you Test the Impermeability ?

Dry a part of the substance till it ceases to lose weight ;
then steep in water for twenty-four hours and then wipe, dry,
and re-weigh ; the best pipes absorb the least,
52

How would you Test their Chemical Resistance ?

Pulverise a small piece and boil it in hydrochloric acid,
and note the loss of weight. The clay should contain no lime,
because this when moist renders the pipes rotten,

How should the Pipes be Laid ?

The spigot end of the pipe is to be laid into the socket
of the other, and the spigot end directed or laid DOWNHILL,
The socket and pipe should be made in one piece. The pipe
must rest throughout its ENTIRE LENGTH on the ground, so that
it is necessary to cut out a small depression to hold the socket,
or else carefully pack up the part under the pipe, to give
support. Cement joints should be used, and the pipes must
be carefully held till it sets, and see that none passes into
the pipe and so roughens the interior. When the sewer is
conveyed under a dwelling, the pipes should be laid in asphalt.
Roman cement ‘sets more quickly than Portland cement, If
the pipes merely rest on the two ends, the pipe becomes
a girder, and breaks from the weight of earth above. Sewers
with vertical or straight sides require 50 per cent. greater
thickness than curved ones of the same dimensions.

What are the Objections to Ordinary Mortar in Sewer Building ?

1. The ammonia becomes oxidised into nitrous and nitric
acids, and forms soluble compounds with the calcium, which is
then washed away.

2. The carbonic acid in the sewage makes it take up some
of the lime in solution and removes it, so that only sand is left,
and the sewers therefore fail. Hence, therefore, always test
the mortar or cement by nitric acid before using ; let it stand
for ten days in a 10 per cent. solution, and it will be found that
Portland cement is the best.

In Flushing Sewers where would you Begin ?

Always begin at the lower parts of the district first, and
gradually work your way to the higher parts.
53
What ure the Effects of Heat in Sewers ?

It expands the air, and if the sewer is not properly ventilated
may force traps and leave them unsealed. ‘The temperature
varies with hot liquids and seasons.

In sewers the—

Summer temperature is below that of the atmosphere.

In Spring it is just equal to it.

In Autumn and Winter it is above the temperature
of the outside air.

Hot water expands the air and also heats the other water
present, and makes it less able to hold the foul gases in solution ;
hence, a rise of temperature makes the air of sewers offensive.

What are the Effects of the Ebb and Flow in Sewers ?

It leaves the sides of the sewers alternately wet and dry,
and thus leads to the production of vapour, and compresses the
air or allows it to expand as the case may be, and will force
the traps if there is no proper ventilation. Sewers from
morning till noon are expelling foul air, due to the “ flow ;” but
from noon till morn they are drawing in fresh air—the “ ebb.”
Sewers discharging into the sea or tidal rivers are apt to be
tide-locked twice a day, and fill with sewage, so that the gas
is forced out; and then during the ebb the air is drawn in.
These fluctuations, due to ebb and flow, make it necessary that
the sewers should be properly ventilated.

What Effect has Barometric Changes on Sewers ?

When the barometer, falls the pressure is less, and there
is an escape of sewer gas, and it also favours decomposition ;
an increase of barometric pressure (when the barometer “ rises”
enables the air to carry more watery vapour, and the sewage also
retains a larger volume of offensive gases in solution. A rapid
fall liberates foul air from the sewage, and hence the bad smells
felt in the streets and elsewhere ; but this is not due to defective
construction necessarily. Sewage at a high level contains air of
D4

less tension than sewage at a low level, and therefore in passing
from a higher to a lower level it tends to take up more air; and
hence FLOWING sewage tends to retain foul air in solution.

Give a List of the Forces Acting in Sewers ?

1. Gravity, the cause of the flow.

2. Heat, from hot liquids, ete.

3. The force of the ebb and flow.

4, Barometric changes.

5, Wind blowing up out-fall sewer, the end of which, there-
fore, should be protected.

6. Friction and leakage.

What is the Objection to Ordinary Ventilating Shafts ?

They are useless if the heat of the outside air be greater
than the air in the sewer, and at the season when ventilation
is most required it is of no use—z.e., in Summer.

Could we Use the Chimney Shafts of Manufactories ?

They might be used but there are many objections :—
. It spoils their use as chimneys.
. They must be larger than the manufactory requires.
. They are in private hands,
. They are useless when the fires are out, as on
holidays.
5. The gas, being often combustible, it may lead to
explosions.

Occasionally this plan is useful for the PartraL ventilation
of sewers, or of the sewage tanks at pumping stations. Lamp
columns may be used with advantage as ventilating shafts.

Hm Co bo

Should Rain Water Pipes be Used for Sewer Ventilation ?

No; in any case they would only be of use for house drains,
for in times of rain the end of the house drain is covered in
the sewer, so that gases could not get up. The water, too, in
the rain pipes would absorb the gases and carry them down.
55

Further, these pipes are under the eaves of houses and near
windows, so that gases would gain admission to the houses.
It is better to have short shafts of large area in the streets ;
they are as good as small ones of great height, and even better,
as there is less friction, and less pressure exists in the sewers
behind them.

What is the Objection to Ventilating into the Streets ?

It is bad, especially for children, and more especially in
narrow streets and confined places; the great safeguard is free
dilution of the foul air with the fresh outside air.

How may Water Traps Lose their Seal ?

1, The water may dry up.

2. The pipe may run full bore, and run past with such
velocity as not to remain in the bend at all.

3. It may be sucked out by a mere rag lying over the edge,
as a bit of dust cloth, this acting like the wick of a lamp.

4, It may be forced back by pressure inside the sewer, for
expansion of gases, etc. To these must be added bad con-
struction, insufficient dip, and inefficient ventilation.

To remedy this, flush the traps frequently, and have free
ventilation on both sides of the trap, and let the water run
into the pipes AFTER flushing.

How does a Firth or Tidal River Differ from the Sea ?

In tidal rivers and firths the ebb is much longer than the
flow, and therefore it is much better for the carrying away of
the sewage.

What ts a Penstock ?

It is a sluice fixed in a sewer to regulate or control the
current —e.g., to stop the flow and pen up the sewage for
flushing purposes. It is necessary in tidal out-falls as an
adjunct to tidal valves ; it is also used to direct the sewage
from one line into another,
56

When are “ Tank Sewers” Necessary ?

They are necessary when the sewers are tide-locked, and some-
times when pumping is necessary ; also in discharges into tidal
rivers, to collect the sewage during the flow tide, and discharge
it during the ebb tide, as this carries the sewage away. They
are formed by enlarging the out-fall sewer or some convenient
branch sewer, to store up the sewage for the time required.
Sometimes reservoirs are used instead, but tank sewers are
better, though they take a little longer to empty.

When are Inverted Syphons Used ?

They are used in carrying the sewage across navigable rivers,
streams, or valleys, and should be self-cleansing ; they should
have a wire rope or chain in the interior, so as to stir up any
sludge that may settle.

What is Necessary when the House Drains Come Through the
Wall ?

They must have ample space, and the part be protected by
an arch not resting on the pipe; if not, the pipes often fail
in new buildings, being broken by the “settling” of the walls
of the house.

What are the Best Pipes ?

Glazed stoneware. Sewer air and bits of lime will soon
corrode Leap pipes; Iron pipes become coated inside with a
layer of oxide, and feecel matters adhere to it; and Zc pipes
are very bad, as they are very soon corroded by the chemical
action of the feecal matters.

Edinburgh: Printed by H. & S. Lrvinostonx, 4 Melbourne Place,
J 69S

CATECHISM SERIES.

PUBLIC HEALTH:

 

WiLDAL olALlS i IGs:

LIFE INSURANCE.
DWELLINGS. CLIMATE.

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PRINTED BY
E. & S. LIVINGSTONE
4 MELBOURNE PLACE

EDINBURGH.
PREFACE.

T is hoped that the method of Question and Answer
here adopted will aid the Student in preparing

his work for Examinations—by suggesting possible
questions that otherwise might have escaped his
notice. In this way the book will be a great and
useful means of self-tuition, The small size of the
book, too, the absence of “packing,” will enable him
to run over the work the night before the Examination,

and recall the most important points to his memory.
PUBLIC HEALTH.

 

VITAL STATISTICS.

What is meant by this Term ?

It is the science of figures applied to the health history
of countries, and the study of the laws that govern the physical
condition of mankind. It deals with births, marriages, and
deaths, the diseases from which we die or suffer, and takes
into consideration age, sex, occupation of individuals, as well
as the diseases.

What are the Sources of Information ?
1. The Census returns.
2. Returns of births, marriages, and deaths by registration.

What Acts Relate to this ?

The English Registration Act of 1838, which was im-
perfect : it was improved in 1871. The Scotch Act, passed
in 1855, was much better.

What are the Uses of Vital Statistics ?

1. It gives information as to the health of the people.

2. It gives information as to the good or evil conditions
affecting the people.

3..It enables us to apply the above information to Life
Assurance.

4, It shows the fatality of different diseases at different
ages.

5. It shows also the influence of professions, trades,
locality, and age, on the well-being of the community.
6
How are the Returns Classified ?

They are classified according to the divisions and sub-
divisions of the country, as — Counties, Towns, Unions,
Parishes, Villages, and Streets, or Urban and Rural districts.
The districts in Scotland are Insular, Mainland, and Rural ;
and the towns are divided into—

Principat Towns—eight innumber— with populations
over 25,000.

Larcer Towns, with populations of from 10,000 to
25,000. ;

SMALLER Towns, with populations of from 2000 to
10,000.

Name the Eight Principal Towns.
1. Aberdeen.

. Edinburgh.

. Leith.

Dundee.

Glasgow.

Perth.

. Greenock.

. Paisley.

Go NS OUP ww bo

Who has the Charge of this Branch ?

All the charge of the Vital Statistics is entrusted to three
Registrars-General — in Scotland, England, and Ireland,—
who publish Yearly and Quarterly Reports for the whole
country, and Weekly Reports for certain large towns,

What is the “ Census” ?
It is the actual enumeration of the population.

How Often is tt Taken ?

In Great Britain it is taken every ten years. It has been
taken ten times: the first was on 10th March 1801, and the
last on Sth April 1891.
Tow is tt Taken ?

It is taken rapidly and simultaneously, by means of
schedules distributed all over the country, and these are all
filled up on a fixed date previously determined upon.

What Information does the Census Give ?

Besides the actual number of the population, it gives the
name, age, sex, rank or profession, and condition of every
person, and the relation they bear to the head of the family.
It also gives the number of inhabited and uninhabited
houses ; and enables us to group the population according
to age, sex, etc.

Whether are Males or Females more Numerous ?

Females: in England and Wales alone the excess is
close on a million.

To what is the Increase of Population Due ?

The IncREASE depends chiefly on the birth and death
rates: emigration and immigration affect it but very little.
During the last ten years there has been a very rapid
increase, due to the high birth-rate and the low death-rate ;
the high birth-rate gives an extra 26,774 persons, and the
low death-rate means the survival of 299,385 persons who
would have died if the death-rate had been as high as it was
during the previous ten years.

What is the “ Natural Increment” of the People?

It is the excess of births over deaths. The “actual
increment” can only be determined by ennumeration.

How is the Populution Estimated during the Ten Years
between one Census and the newt ?

We must first find the “estimate of population.” One
plan is to assume that the rate of increase between the past
8

census and the next will be the same as the rate of increase
between the last census and the previous one. Another
method is to add to the population of the district in question,
as enumerated at the last census, one-tenth the difference
between that number and the number obtained at the
previous census, for each year that has elapsed since the last
census ; and this will give the population for the end of the
first quarter—the period of the year during which the
census is taken. The death-rate, however, is calculated on
the estimated population of the second quarter—or the
middle of the year; so one-fourth part of the annual, or
one-fortieth of the actual, increase for the ten years, which
has taken place between the last census and the previous,
must be added to represent the increment for the additional
quarter. This method does not apply to new and rapidly
increasing districts; in this case we must find the number
of the houses in the district and the average number in each.
In finding the estimated population, take into account—

1, The excess of births over deaths.
2. The amount of emigration.

3. The amount of immigration.

4, The marriage registration.

Give a Detailed Example.
Take Edinburgh—

Population in 1881 was - - 228,346
Population in 1871 was - Se SLOG S78
Difference = 31,367

and this is = the increase for the ten years. The yearly
increase is of course one-tenth of this, or 3137, and this
added to each year will give the estimated population ; and
this number also is—the average increase for each year,

Now to find the death-rate, say for the year 1883.
y

The number of deaths was eighty-four in one week, and
this multiplied by 52 is = 4368, which is = the total
death-rate, provided the death-rate remained the same all
the year through.

But 1883 is two years after the census, and therefore add
to the population of 1881, twice 3137, to give the average
increase for the two years, and 228,346 +6274 = 234,620,
and this is the estimated population of 1883.

Then to find out the number of deaths per 1000,
multiply the total assumed death-rate for the year—4368—
by 1000, and divide by the population of that year (1883)
and this will give the number of deaths per 1000 of the
estimated population—

4368 x 1000 = 4,368,000, and

4,368,000 + 234,620 = 18:6,
and this is = the death-rate per 1000 during the year 1883.
To this, however, a little should be added to make up for
the extra quarter—from April to June inclusive—say 19
per 1000.

In registration the CAUSE OF DEATH is the most important,
and this may either be primary or secondary, thus—

In Enteric Fever death is often from Pneumonia.

In Scarlet Fever from Nephritis.

In Measles and Hooping-Cough from Bronchitis.
Phithsis from Diarrhcea.
Rheumatic Fever from Endocarditis.

What Circumstances will Affect the Mortality Statistics ?

1. Fluctuations of populations.
Prosperous or adverse times.
Peace or war.

State of the weather.

Improved Sanitary arrangements.

, Epidemics,

SS SS
10
What are the Sources of Information ?

The Registrar-General’s Reports; and for any special
district, the books of the District Registrar and those of the
Board of Guardians.

What Points should the Health Officer’s Weekly Report
Include ?
I. THe Birtu-ratE—
1. Live-born.
2. Still-born.
Il. Toe MarriaGE-rate.
III. Toran Deatu-Rate—
1. Death-rate at different ages—
(1) In Infancy—
(a) First week.
(d) First year.
(2) In Adults.
2. Death-rate from Zymotic diseases.
3. Classified death-rate from other causes.
4. Degree of healthiness or unhealthiness of the
district -—
(1) Number of persons constantly sick,

arranged according to age, sex, occu-
pation, and disease.

(2) Average duration of illness.
What is the Rate of Mortality ?
The number of deaths within any given area.
What is meant by “ Expectation of Life” or “ After Life
Time” ?

The probability of the age any one person of a given
population will attain, according to the rate of mortality
14

found to prevail within that area, regard being had to the
age of the party at the time of fixing the expectation.

How is tt Calculated ?

Willich’s formula is to take two-thirds of 80, minus the
age of the person. Thus at twenty the expectation of life
is 80—20 = 60, and two-thirds of 60 is = 40—die., the
person will in all probability, live for forty years.

Whut is the Law of Population Increase ?

Population, when unchecked, goes on doubling itself
every 25 years, or tends to increase in a geometrical ratio-—
i.e, 1, 2, 4, 8, 16, 32, ete. ; hence, the larger the population
the more rapidly, apparently, does it increase.

What Points should be Contained in a Death Certificate ?
1. Place.

Date.

Age.

Sex.

. Employment.

_ Cause of death, and whether primary or secondary
or both.

Dow wb

What is the Normal Death-Rate ?

About 11 per 1000; but in a town, 17 per 1000 indicates
a very healthy condition, and may be taken as a very fair
standard.

What is meant by “ Climaterics” ?

It is a popular belief that the years of human life, pro-
duced by multiplying 7 into the odd numbers 1, ay, 5-9;
are climacteric; and the last is the “grand climateric” for

men—?.e., 63; and the one before that the grand climateric
for women—ieé., £9.
12
What ts meant by the Death-Rate or Death - Toll ?
The yearly amount of mortality in the population,

expressed as the number of deaths occurring annually in
every 1000 of the population.

From what Datu ts it Ascertained ?

From the Registrar-General’s Annual Report of the
Mortality of the United Kingdom, but this only gives the
country taken as a whole. For any given district it must
be taken from the actual or estimated population, and by
consulting the books of the District Registrar and the books
of the Board of Guardians.

State, approximately, the Mean Death-Rate of Great Britian.
England and Wales, for 21 years—
Males = 23:15
Females = 21:58
Both = 22:36
In Scotland it is rather smaller—being 22:054.

What Causes Raise the Death-Rate in Towns ?

1. Over-crowding. The death-rate is high in direct, pro-
portion to crowding.

2. Want of fresh air and pure water.

3. Insufficient accommodation and bad drainage.

4, Profligate and intemperate habits.

5. Accidents.

6. In London and other large towns, many die in the
hospitals who ought to be accredited to the country. The
death-rate of many watering-places is high, because of the
numbers who go for the benefit of health, but only to die.

How is the Estimated Population of a District Obtained
according to the method pursued by the Registrar-
General ?

See page 7,
13

What is the Birth-Rate ?

It is the total births per year, divided into the rate per
1000 of the population living in the district at all ages.

Are Boys or Girls more Numerous at Birth ?

The male births are most numerous. In England and
Wales, the excess of boys is smaller than anywhere else ;
and it is greatest in Italy.

How does Place Affect the Birth-Rate ?

In urban districts the birth-rate is high, because the
marriage-rate is high, and the women are necessarily younger
than in country districts ; also, there is a high rate of infant
mortality, and this shortens the intervals of child-bearing.

In fashionable towns where there is a large number of
unmarried servants employed, the birth-rate is always low.

What is the Relation between the Birth-Rate and the Death-
Rate ? |
Where the birth-rate is high, so also is the death-rate for
that special town, because so many children die in infancy.

Is the Number of Illegitimate Births, a test of the Morality
of a Country or Nation ?

No, not necessarily. Of course if the percentage be
high the morality must be low in that particular branch ;
but a low percentage of illegitimate births is no evidence
of a high moral tone.

Give an Example ?

It is generally admitted that the French are the most
immoral people of modern times—of the truth or otherwise
of this assertion the writer has no personal experience, and
therefore cannot pronounce upon the truth of this statement,
—and yet it is the country with the smallest proportion of
illegitimate births.
14
How is this ?

Because the more immoral an individual or nation
becomes, they acquire the pernicious science of preventing
the natural consequences of their immorality—by taking
steps to prevent conception altogether, or else procuring
abortion at a later period.

Does the Total Death-Rate of a Country Represent the Actual
Death-Rate of any given District ?

.

No; the total annual death-rate does not represent the
actual death-rate in small sanitary districts. In estimating
the actual death-rate, corrections must be made for persons
not belonging to the district, as in hospitals, workhouses,
asylums, and for visitors, and also for deaths of persons
belonging to it but dying outside the district: the death-
rate of the division where the workhouse is will be higher
than it REALLY is, unless a correction be made as to the
residence of those dying in it; and the death-rate of the
surrounding district, will appear smaller than it really is,
unless indoor paupers belonging to it be counted: hence,
the importance of ascertaining the exact residence of those
dying.

Name the Zymotic Diseases.
Small-pox.
Measles.
Scarlatina.
Diphtheria.
Whooping-Cough.
Typhus and Typhoid Fevers.
Erysipelas. -

What is meant by “ Infant Mortality” ?

The total number of deaths under one year, compared with
the births, registered and expressed as so many per 1000.
15

What is the “ Rate” of Infant Mortality ?

The annual rate in England and Wales in 1882 was 141
per 1000: and the average for the ten previous years was
150 per 1000.

Seventeen per cent. die during the first year. One-third
of all deaths are children, and one-half of all before the
fifth year. Of every 1000 children born, 500 die within the
first five years of life—z.e., 50 per cent.

What are the Causes of this High Rate of Infant Mortality ?

During the first two years these are chiefly—teething,
digestive disturbances, and fevers.

1. Diseases of the Nervous System form the most
common cause of death during the first year, and is the
second most common cause under five years of age. The
convulsions of the child take the place of delirium in the
adult ; this is due to the predominence of the spinal cord over
the brain in the child. The Nervous affections may be—

(1) “ Functional ”—e.g., Convulsions, Chorea, Epilepsy.
4) “ Organic,” as Hydrocephalus.
. The Respiratory SystemM.—Diseases of this denier
a the most common cause of death under five years of
age ; as bronchitis, pneumonia, laryngitis (croup), phthisis,

3. The Digestive System comes next; as “ indigestion,”
vomiting, diarrhoea, constipation, leading on sometimes to
convulsions and death.

Give the Rate of Mortality at Various Ages ?

First year—17 per cent. die.

Under five years—50 per cent. die.

From this to puberty the rate of mortality declines, and
then SLOWLY increases up to 50 or 60 years: from this to
the end it increases at such a rate that it is doubled every
ten years.
16
How does Locality Affect the Death-Rate ?

It is high in towns and low in the country: in towns it
varies at different parts—in fact it increases in proportion to
the density of the population. In fashionable suburbs where
there is a large excess of adults of the ages in which a low
death-rate prevails, and where also the birth-rate is also low,
the death-rate is usually very low. In poor and crowded
places where no servants are kept, and where the birth-rate
is high, the death-rate is usually very high for reasons
already explained.

How does Season Affect the Death-Rate ?

Winter predisposes to diseases of the respiratory organs,
especially if the temperature be very low; summer pre-
disposes to intestinal disorders, and more especially if the
temperature be very high: the high temperature increases
the sick and death-rate from diarrhoea and filth diseases.
The death-rate is highest during the first quarter of the year
and lowest during the third quarter.

What does Longevity Embrace ?
It embraces—
1. The mean age at death.
2. The “expectation of life” or the ‘mean after
life time,” at various ages.

How do you Find the Mean Age at Death ?

Divide the sum total of the ages at death by the number
of deaths. It varies according to the proportion of young
and old; if the birth-rate be high, the “mean age” will be
low because of the high infant mortality. The mean age at
death is—

In England, - - 40 years.
In France, - - 34 years.
In Sweden, - - 31 years.
hf

What are the Periods of Life ?
First dependent period, from 0 to 20 years.

Useful or productive period, from 20 to 60 years.
Second dependent period, from 60 onwards.

What Effect hus Sanitation on these Periods ?

It has chiefly increased the useful or productive period.

What is meant by Morbidity ?

It means the “sick-rate,” or the amount of illness in a
community: for every death there are two years of severe
sickness.

In Judging of the Death-Rate, what Points should be
Considered ?

1. It may be due to a preponderance of adult and selected
lives, while the sanitary condition is by no means good.

2. It may not be above the average all over, while at
some parts it is excessively high.

3. A good sanitary condition is shown by the low death-
rate from INFECTIOUS diseases, fever, diarrhoea, and phthisis ;
and amongst children under five years from all causes.

4, Also consider the social causes, as intemperance, im-
morality, early and injudicious marriages.

What is a ‘‘ Legal Infant” ?

Any person under twenty-one years of age.

Give some Examples of the Effect of Occupations on the
Death-Rate.

Stone-masons, lapidaries, knife-grinders, especially “ dry”
grinding pin-pointers, button-makers, pottery workers, and
flax-hacklers, suffer much from lung affections, and very
often die young.

B
18

LIFE INSURANCE.

What is meant by this ?

It is a contract by which a person, termed the INSURER,
in consideration of a sum of money proportioned to the risk
(the PREMIUM), becomes bound to pay to the legal repre-
sentatives of the INSURED at his death, or to the insured
himself on his attaining a certain age, a sum of money
previously agreed upon at the time of making the contract.
The contract must be drawn up on stamped paper to be a
legal instrument. By this means individual members relieve
the State of the burden of keeping their offspring, ete.

How many Kinds of Life Insurance are there ?

1. The Proprietary.
2. The Mixed.
3. The Mutual.

Lzplain these more Fully.

In the Proprietary a FIXED sum is paid, the profits being
all divided among the proprietors.

In the Mrxep, the insured participate in a portion of the
profits, the rest being divided among the proprietors.

In the Murtvat, after paying expenses of management, the
whole of the profits are divided among the insured.

What is the Principle Underlying any System of Life
Insurance ?

The whole system is based upon the probable duration
of human life, and the value of the contributions of the
members of the society placed at compound interest.
19
How is the Probable Duration of Life Determined ?

By means of “life tables”—7.e., tables showing the
probable duration of life.

Name some such Tables 2?

1. The Breslau Table of Mortality, drawn up from the
Registers of the town of Breslau, in Silesia, by Dr Halley.

2. De Moivre’s two Tables.

3. The Northampton Table (Dr Price).

4, The Carlisle Table (Dr Heysham).

5. The English Life Tables (Dr Farr).

Comment on the following Cuse :—

A. B., compositor, aged 25, is proposed for insurance.
His father died at 30, “from a neglected cold.” <A sister
died at 17, ‘from bursting a blood vessel.” No other death
in the family. Height of A. B., 5 feet 10 inches; weight,
10 stones. No physical signs of disease are discovered on
examination. He has no complaints, except occasional
dyspepsia. Now—

1, What fuller Information is Required as to the
Family History ?

2. Is his Weight Satisfactory? If not, what should
it be?

3. Considering his Occupation, Family History, Bodily
Conformation, and Personal Health History,
state your Opinion, so far as the above State:
ments go, as to his Hligibility for Insurance.
20

FAMILY HISTORY.

1. You would have to find out about his mother, as to
her hereditary tendencies and present state of health. Also,
if he has any other brothers or sisters, and their present
state of health. Also about his father, whether he had
any inherited tendencies from urs parents, and also whether
HIS brothers or sisters are alive and well—if he had any.
The father’s occupation, habits as to food and drink, and
his general surroundings at home and at work, and his
previous attacks of illness and their nature, making special
inquiry for a possible history of Fistula in ano—in general
popular language, everything wrong in the region of the
anus is called “ piles.”

WEIGHT.
2. His weight is not satisfactory; it ought to be 12 stones
at least.

ELIGIBILITY.

3. The case is not a good one for insurance, and could
not be taken at the usual premium. His occupation is one
of the worst for a person at all predisposed to phthisis ; it is
often enough to bring on phthisis in the healthy, how much
more so in a case where the hereditary predisposition is
marked. The family history is not good: “neglected colds”
and “bronchitis” in popular language nearly always mean
phthisis pulmonalis. So also does bursting of a blood-
vessel: and the age—30 in the one case and 17 in the
other—supports this view. His weight is important, and it
is not enough; and with the history of occasional dyspepsia,
is still more suspicious, Looking at everything, the life is
not a “good” one,
21

What is the Relation of the Weight of an Individual to his
Height ?

The following table (Hutchinson’s) shows the relation-

ship :—

FEET INCHES ST. LBS.
A person 95 1 high should weigh 8 8
" 5 2 " 9 0
"! 5 3 " 9 4
" 5 4 " 9.18
"! 5 5 " 10 2
" 5 6 " io
" 5 7 " 10° > 3
"! 5 8 "! 11 i
" 5 9 " 11 ae
" D0 " 12.8
" Det " 12 22%
" 6 0 " 12 10

What is the “ Vital Capacity” of a Person ?

The “vital capacity” or the “extreme differential
capacity” is a term used to express the total amount of air
that can be given out by the most forcible expiration, after
the most forcible inspiration.

What is the Average Quantity, and how is tt affected by
Height ?
It is 230 cubic inches for a person 5 feet 8 inches high,

and increases or diminishes 8 cubic inches for every inch
above or below that height. (“ Hutchinson’s Law.” )
22

DWELLINGS.
What ts a Dwelling ?

livery structure inhabited by human beings, either con-
stantly or temporarily—e.g., hospital, school, factory, etc.,
and whether in town or village, park or paddock.

What is Important in Regard to the Site of a Dwelling ?

The site must be DRAINED—not SEWERED,-—and also the
ground-room dwellings. The ground is then able to absorb
so much liquid filth, and by the oxygen in it oxidise it
into harmless products. Drainage also prevents the up-
rising of the polluted liquid in the soil— ground-water ”—
and evolution of foul gases from evaporation into the air
permeating the basements of the dwellings. It also raises
the temperature slightly, as it prevents evaporation—by
removing the water from below; and water when it
evaporates must get its latent heat somehow, and in this
case it would take it from the air in the dwelling.

What Disease is Specially Associated with Wet Subsotl in
Towns—e.g., Damp Rooms or Floors ?

In towns on wet subsoil there is much phthisis, and the
wetter the worse; in towns standing on dry subsoil, there
is less phthisis.

Give Examples of this ?

After draining the subsoil the death-rate from phthisis
fell— :
49 per cent. at Salisbury.
47 per cent. at Ely.
43 per cent. at Rugby.
Lo
Cs

How was this Discovered ?

Quite by accident, in the case of Salisbury: new sewers
were laid, which also removed the subsoil water; but
although in this case much good resulted, yet, as a general
rule, the sewers should not act as drains for the subsoil
through which they pass.

What is the Result of Wet Soils in Districts (not Towns) ?

Ague: especially if the soil be loaded with vegetable
organic matters, and be only parTiaLLy under cover of the
water, so that parts are alternately moist and dry, as this
favours organic decomposition.

How was this Cured in the Fen District ?

By drainage, ague has almost disappeared from the Fens.
Ague was once the rule in every family during the Spring.
It sometimes recurs yet—not in spring but in Autumn,—
because the drainage was too complete ; so that during the
summer months and at the end of harvest the ditches are
NEARLY DRY, and therefore form an exhaling or evaporating
surface for noxious effluvia from decaying vegetable matters.
The draining, therefore, should be judicious.

How ts this Difficulty Got Over ?

The farmers let water into the ditches from rivers, during
the summer months, so as to “keep a water” always in the
ditches, and as nearly as possible at one level.

What Effect has Drainage of the Soil upon the Temperature ?

The temperature of drained land is raised from 13° to 3°,
which is equivalent to being transported 100 to 150 miles
southwards.
24
Explain this Effect.

The rain falls and fills the soil, and as there are no sub-
soil drains, there is no escape for it, but it is imprisoned in
the soil, and evaporates from this. Take 30 inches of rain
on every acre per year, and the daily weight of water
evaporated is equal to 8} tons. But watery vapour is just
steam, and in transforming water into steam 536 thermal
units are rendered “latent:” in other words, the heat
necessary to yaporise 84 tons of water would correspond
to 24 cwt. of coal in a steam boiler; every grain of water
requires heat enough to raise 960 grains 1° Fahr. Now this
large amount of heat must come from somewhere, and it
comes from the soil and the atmosphere round about the
wet land. The water evaporated is proportional to the
surface exposed; and hence is much greater from porous

solids kept wet—eg., the porous soll—THAN FROM THE
SURFACE OF WATER ITSELF.

Mention some other Beneficial Effects of Drainage.

It tends to keep the air pure, as it allows oxygen to
penetrate into the soil and oxidise organic matters, and
saves from scrofula and phthisis. Foul air fosters enteric
fever, catarrhs, bronchitis, pneumonia, inflammation of the
eyes, helps the spread of small-pox and scarlet-fever, and
prevents or retards the healing of wounds.

Give the Aspect and Shelter of the Site of Dwellings, and the
State of the Soil under and around.

The aspect—south-east. It should be sue_TERED from
the east and north-east winds. The soil under and around
should be dry, and if not naturally so it should be drained.
25
Classify Soils in Cellars and Basements.

1. Those that are impervious, and that resist absorption
—e.g., rocks, :

2. Those that are pervious and retentive, and absorb and
give off slowly—e.g., Clays.

3. Those that are pervious and free, and absorb and give
off quickly—e.g., Sands, Gravels, Chalks, and Mixed Soils.

What Amount of Water do these Soils Absorb ?

Granite and marble, hold a pint per cubic yard; red
sandstone holds 27 pints per cubic yard; and loose sandy
soils hold 40 to 50 gallons per cubic yard.

What ts the Result ?

They all keep the walls and floors damp, and in summer
they defile the ground air.

What is the Effect of Clay Subsoil ?

Clay subsoils give off vapour slowly, but in the end give
off more than free soils; hence, they are “‘cold” and form
very bad sites. Sand is like so many capillary tubes, and
the more holes the greater the surface and the greater the
evaporation. ‘ Water-logged” soils are bad, until the
subsoil water is lowered by drainage, not only to prevent
evaporation, but also to prevent the rise of water by
“ capillary attraction” to the cellar floors and foundations.

Is the Side of a River a Good Site ?

No, not unless it is well drained, because of capillary
attraction, keeping the basement and walls damp. Lung
diseases, rheumatism, and heart complaints increase in
proportion as the wetness increases.
26
How does the Mode of Drainage Differ in different Subsoils ?

If the soil is “free” a single drain will do for a wide
area, and should be as far from the building as possible,
lest they carry off sand, etc., and lead to “settlements” of
the walls of the house. In stiff clay soils the greater the
number of drains the better. Protect the drains from
roots of trees. Avoid if possible placing them under the
building and protect from the pressure of the walls, if it is
necessary.

How is the Water Prevented from Rising by Capillary
Attraction ?

To prevent the water rising in the walls and floors, lay
a bed of concrete six inches deep all over the base of the
dwelling, the walls on a foundation of concrete, and have
‘damp courses””—impervious cement and slate or asphalte
between the courses of bricks or stones—some use perforated
tiles ; and again hollow walls are good for damp. If the
basement floor is below the level of the natural surface of
the ground, there should be an area between it and the
house wall, as well as proper drains and sewers.

Would this Plan be Good in Clay Subsoils ?

No; in clay soils there should be no basements or cellars,
because they would always be damp, and therefore cold,
clay being so retentive. In this case the foundations should
be raised above the level of the clay, with free ventilation
between the surface and the floor of the dwelling.

What is the Cause of “‘ Dry Rot” ?

It is due to the growth of a fungus fostered by the damp
and darkness—e.g., as from dripping roofs. If once begun
it persists through dry and damp and darkness and light.
27
Are Old Sites cr Rubbish Heaps Good Sites ?

Must not build on rubbish heaps for at least two or three
years. If rebuilding on an old site, should take up all the
old drains and cess-pits, and have old wells all filled up with
concrete.

What Diseases Result from Dampness ?

Rheumatism, phthisis and bronchitis, and heart affections.

What Diseases Arise from Filth ?

Diphtheria, ulcerated sore throat, follicular tonsillitis,
croup, enteric fever, follicular stomatitis, diarrhoea, dysentery,
erysipelas, carbuncle, abscess, pysmia, hospital gangrene,
puerperal fever, infectious and epidemic filth pneumonia.

How Deep should the Drains be ?

They should be so deep that the subsoil water will not
rise within three feet of the foundations, and one foot must
be allowed for capillary attraction.

Are Porous Walls Good ?

They are not the best, as they absorb moisture and
organic matters, and by-and-by become a source of pollution.
If they are damp air cannot enter, as the pores are filled with
water, so that oxidation cannot go on, and the evaporation
of the water cools down the temperature. Parian cement is
impervious, but inelastic and apt to crack; the best coating
is good plaster, hme-whited ; it should be scraped now and
again and re-whited. A hollow wall loses less heat than a
solid one. Basements are like the soil, warmer in winter
and colder in summer.
28

Note then. Buildings should be—

1. Fire-proof.

2. Have a free circulation of air in and around, hence
they should not be back to back nor over stables.

3. On well-drained ground.

4, Have lofty rooms.

5. Plenty of light.

6. The water-closets, in projecting towers, or as far from
the house as possible.

7. Always have a map of the drains, sewers, and piping
of the house.

Squares with closed angles are bad as this prevents the
free circulation of air.

Glass roofs lose much heat; it is better to have a double
window, and in winter to warm the space between. Iron
and glass roofs, to be kept cool in summer, should be watered
by jets; lime-whiting also protects from heat. Windows
lose heat by radiation and conduction; less heat is lost
by double windows. The window space in houses should
be 1 square foot for every 100; in hospitals it should
be 1 square foot for every 60.

What Points should be attended to in Hot Water Apparatus ?

1. The boiler should be of wrought iron, properly tested
before use.

2. It should be inspected occasionally, and if necessary
cleaned.

3. Its pipes should be carried up within the building,
and not against an external wall.

4, Its cisterns should be placed in a position easy of
access, and well protected from frost.

5. Its safety valve should be easily adjusted, sensitive,
and placed in an easily accessible position to be taken to
29

pieces and refixed. Use valve of 135 lbs. to square inch,
or 9 atmospheres.

If there is no boiler, but merely a coil of pipes, as in
Perkin’s method, it is necessary to use an “ expansion pipe”
at the highest point of the apparatus, as water in being
heated from the freezing to the boiling point expands one-
twenty-third of its bulk; in filling the pipes, leave the
expansion pipe empty.

How would you judge of the Temperature of these Pipes ?

File a bright part on the pipes and watch the colour :—
If it becomes pale straw colour = 450° F.
If it becomes purple = 530° F,
If it becomes blue = 560° F.

What Relation has the Subsoil Water to Phthisis, Enteric
Fever, and Cholera ?

Any kind of wet subsoil gives rise to phthisis, whatever
the level of the water may be or its variation in level from
time to time; the strata may either be retentive of wet, or
they may be flat, so that they become “ water-logged.” If
saturated with sea-water it does not cause phthisis, and there
is but a small area of water level and it is often changed.

Any great or sudden change in the level of the subsoil
water, plus or minus, is almost sure to be followed by
epidemics of enteric fever. Without this change in the
waiter level, excremental pollution appears to be inoperative
in producing epidemic diseases. ‘The cholera in India is
coincident with low level of the subsoil water. Of course
it is not due alone to the fluctuation of the water level; but
this plus excremental pollution is enough, and is specially
favoured by certain kinds of soil. This shows the great
danger of leaky sewers in the presence of subsoil water,

 
30

Subsoil water is always on the move towards the sea or
rivers, and ready to carry pollution with it; in sloping
ground disease due to excremental pollution occurs only at
the lowest part. Excremental pollution also affects the
“sround air,” and the hot air and lessened pressure in
houses tends to “draw up” this pollution. It follows from
this that sewers should be perfectly water and air tight.

Should Sewers Act as Subsoil Drains ?

No, not in ordinary cases ; if it be possible to maintain a
constant flow into the sewer from the subsoil, as in swampy
districts, it may be admitted directly into the sewers.

Should Subsoil Drains and Sewers be Laid together ?

It is better not, as the sewers might leak. If they are
laid in the same trench, lay two lines of agricultural pipes
above the clay puddle. The sewers must be impervious.

State what you know about Variations of Temperature under
Different Conditions.

The equator ma 80° .F == Torrid:

80° to 60° - - ce ELOt,

60° to 40° =- - = Temperate.
40° to 24° . - = Cold:

Still colder” - : =—=.Polar,

The temperature lessens 1° F. for every 300 feet above
the earth’s surface, and from the equator to the poles it
lessens 9° F. for every 10° latitude. The proximity of the
ocean also lowers the temperature. Mountain ranges deprive
the winds of moisture and allow of more radiation from the
ground, as well as increased evaporation, and hence it
becomes very cold. Over declivities and rising grounds the
air becomes cooled, and flows down into the valleys, and
forms lakes of cold air.
31
What ws the Special Danger in Hot and Torrid Countries ?

In torrid and hot countries the danger is due to the heat
and moisture which favours decomposition of animal and
vegetable matters, and therefore it is unhealthy.

What is the Temperature of the Soul ?

The daily change does not extend more than 3 feet down,
and never below 40 feet, and the change at 24 feet is
extremely small. As we pass down the temperature increases
1° F. for every 55 feet, or say on an average 1 in 50.

What is the Effect of Snow ?

Snow is a bad conductor, and prevents the passage of heat
from the soil to the air during the winter months.

Is the Soil a good Heat Conductor ?

It varies; loam, clay, and rocks, are better conductors
than sand, and therefore do not become so hot as sand does:
sand becomes hottest of all soils on the surface, and humus
the least.

What is the Effect of Herbage ?

It lessens the amount of heat absorbed, because of the
constant evaporation, that carries so much of the heat away
with it.

What is the Effect of Trees ?

Changes of temperature ‘take place slowly among trees ;
they make the nights warmer and the days cooler. Vegeta-
tion makes the distribution of heat over the twenty-four
hours more equal. Forests lessen evaporation, but increase
32

humidity, because the woods cannot carry it off; they keep
the summer temperature lower and the winter higher—they
thus act like mountains or the sea.

What is the Average Rain-Fall ?
In England it is 32 inches.

How does it Vary ?

On the West Coast of Great Britain and Ireland it is
much greater, and varies from 75. to 150 inches. On the
East Coast of the same parts it is very much less, varying
from 20 to 28 inches. It is increased also by the proximity
of the sea, hills, and forests. In making calculations always
take the maximum and minimum rain-falls, and do not trust
to the average.

What becomes of the Rain ?

About two-thirds are lost by evaporation; plants and
animals use it up; a good deal sinks into the soil and
passes to rivers, the sea, and then evaporates for rain,
dew, etc. On this the moisture and ground water of the
soil depends.

Forests and turf retain the moisture, and protect the soil
and precipitate the rain from clouds; they thus have a very
important bearing in the water supply—e.g., in the Island
of Ascension. Vegetation also causes much evaporation.
Capillary attraction rises highest in chalk, and less in sand.

What is the Effect of Drainage on Temperature ?

It raises the temperature of fields 6° or 7° F., because the
evaporation is less and the percolation greater. Every cubic
foot of water evaporated, lowers the temperature of 3,000,000
cubic feet of air 1° F,
33
How does the “ Ground Air” Vary ?

It depends on the level of the ground water, and moves
in and out according to the barometric pressure and wind:
If there is much water the air carries vapour with it, and the
site therefore is cold and damp. Ground ought to be free
from water, and also from organic impurities. By-and-by
of course it becomes oxidised into harmless products; but
this produces carbonic acid, which is then carried up with
the ground air into the houses—the ‘‘ground air” some-
times contains as much as 50 per cent. of carbonic acid.
Substances decay much more quickly in open, loose soil.

Is Concrete Impervious ?

No, it is not impermeable because of the lime it contains,
and therefore it is better to use asphalte for house foundations
and basement floors.

How are Sites best Arated ?

Have a deep open area around each house below the level
of the basement floor, and have the floor raised. In this way
air can pass into the soil under the house.

Flow does the Ground Water affect the Healthiness of Sites ?

Low subsoil water, say 15 feet down, is healthy; high,
say 5 feet down, is not healthy. A fluctuating level is
specially bad, and still more so if the change of level be
rapid; and worst of all as the water is falling—e.g., fevers
and cholera are apt to follow on the secession of floods, as
the water dries from the soil: it does not come if the soil
be covered with water, because matters are less likely to
decompose. Keep the level low, therefore, if possible by
proper drains; and if it can’t be kept low, at least keep it

at one level.
Cc
34
How can a Damp Subsoil be Detected ?

Fogs appear soon over moist soil; also the vegetation is
greenest, and midges collect over moist places.

How do Plants affect Healthiness ?

They increase the moisture, and at night evolve carbonic
acid gas, and during the day also, if the sun is not shining.
Decayed and fallen leaves therefore, should always be quickly
removed.

How do Local Conditions affect the Sites ?

All sites are bad, if filthy ; to turn up soil impregnated
with decaying organic matters is bad, until the matters are
entirely oxidised—e.g., to turn up marshy land, may cause
an outbreak of ague. Clayey soils are cold and damp,
because of the little percolation, and hence predispose to
rheumatism and catarrhs: sand and gravel are good in this
country, if kept free from organic matters and water. In
hot countries it is bad, because it becomes so hot, unless it is
covered with grass. The air over clay soils is moist, but the
soil is less easily polluted by sewage, as it cannot sink in.

How does Soil affect the Death Rate ?

The fever rate is highest on alluvial clay soils and “ water
logged” ground; the general death-rate is highest on porous
wet soils.

Is an Elevated Site Good ?

Elevation is usually good, unless the wind blows over
marshes and malarial ground—e.g., a town on sloping ground
35

immediately above a marshy plain and with a mountain
range behind, is very bad, and the mortality is sure to be
very great. |

Give a Short Summary of the Points to be Attended to in
Securing a Healthy Site.
1. Avoid clay soils.

2. Avoid the foot of a slope, or deep valleys that receive
drainage from higher levels.

3. Avoid high positions exposed to winds blowing over
marshy ground, as this would predispose to fevers.

4, Elevated sites on the margin, or at the heads of steep
ravines are not, as a rule, good, as malaria may be carried
by air currents flowing up.

5. Rank vegetation is unhealthy, because of so much
decomposing matters in the soil, and also because the ground
is moist below.

6. In warm climates, muddy sea beaches, or river banks,
subject to periodic floodings, or marsh land with brackish
water is very bad.

7. But a porous subsoil, not too much vegetation, a good
fall for drainage, not receiving or retaining the water from
the higher ground, and the prevailing winds not blowing
over marshy land, forms a good site.

8. Also see that the local climate is healthy, soil dry and
porous, protected from the north and east by shelter, at a
sufficient distance to prevent stagnation of the air or damp ;
it should not be on too steep a slope, because the high rising
ground stagnates the air: the circulation of air round about
and under should be quite free. The house should be at
some distance from deep ravines, muddy creeks, ditches, and
undrained marshy ground, A good test is to inquire into
the rate of sickness and mortality in the district.
36

What are Pettenkofer’s Views as to the Cause of Typhoid
Fever ?

He believes that the conditions necessary for typhoid
fever are :—

1. Unusual height of the ground water, followed by a
rapid sinking.

2. Impurity of the soil from animal impregnation.

3. Heat of the soil.

4, Presence of a specific micro-organism or germ.

As already shown when the ground water sinks, air is
drawn into the soil, and when it rises the air is forced out
again more or less impure; the heat and moisture favour

decomposition. Pettenkofer holds the same views with
regard to cholera.

CLIMATE.

What is meant by “ Climate” ?

It embraces all those physical influences connected with
the soil, heat of the atmosphere, or water of a place, which
act and react on man and more or less materially affect his
well-being.

What is meant by “ Meteorology” ?

It is that department of natural philosophy, which treats
of the phenomena of the atmosphere that relate to weather
and climate, or the laws to which they are subject.

How is Climate Divided ?

Into Continental, Insular, and Mixed,
37
Explain these Terms ?

1. A ContTINENTAL climate consists of a very cold winter
and a very hot summer—e.g., Asia.

2. An InsuLar climate is characterised by a cool summer

and a mild winter—e.g., Europe.
3. A Mixep climate is one inclined to be continental in
winter, and insular in summer—e.g., North America.

What Purpose is Served by the Movsture of the Atmosphere ?

Tyndall has shown that the vapour of water exerts
extraordinary energy as a riddant and an absorbent of heat ;
and has shown that, as a consequence of these facts, the
watery vapour suspended in the air serves as a covering or
protection to the earth, shielding it from the sun’s heat
by day, and from the chilling effects of its own radiations
by night.

How can Storms be Predicted ?

In Europe stormy weather is accompanied by a DIMI-
NUTION OF ATMOSPHERIC PRESSURE. The existence of this
diminished pressure is made known by the fall of the
barometer, while the maximum depression is still a con-
siderable distance out in the Atlantic ocean. Collateral
information pointing to an advancing storm, may be obtained
from the direction of the winp and the cirrus cloud.

What Country is specially well Situated for giving Storm
Warnings ?

The United States of America: when the storm appears
in the Western States, bordering on the Rocky Mountains,
38

a message of warning is sent to the Central Office in
Washington ; in this case the prophecy is sure to be correct,
as the storm is actually seen advancing on them.

How is the Atmospheric Pressure Measured ?

By the barometer.

What Height of Mercury does the Atmosphere Support ?

About 30 inches, or 760 millimeters, at the level of the
sea.

What is the Pressure of the Atmosphere ?

Fifteen pounds to the square inch.

What is the Height of a Column of Air Supporting Thirty
Inches of Mercury ?

The heights of the columns of two fluids in equilibrium
are inversely as their specific gravities ; and as air is 10,784
times higher than mercury, the height of the atmosphere
would be 10,784 times 30 inches, or about five miles, if it
were composed of layers of equal density throughout.

What ts the Probable Height of the Atmosphere ?

Probably from fifty to sixty miles, as from its elasticity
and lessened pressure it becomes less and less dense as we
ascend; it may even extend to 200 or 300 miles, though
at fifty miles it is so rare that the effect on the twilight is
nearly inappreciable.
39

Could a Water Barometer be Used ?

Yes, it may be used; but there are several serious
objections— |

1. As water is nearly 14 times heavier than mercury, we
would require a barometric column of water of about 35 feet
long.

2. The space in the tube above the water is far from
being a true vacuum, but is filled with watery vapour, and
this presses upon and depresses the water column, with a
force varying with the temperature: at 32° it depresses it
half-an-inch, and at 75° it is depressed a foot.

The advantage of a water barometer is that it shows
changes of atmospheric pressure on a large scale.

How is the Mercury Prepared ?

It must be boiled in the tube to expel all the air and
moisture, and it must also be perfectly pure, otherwise it
will stick to the tube and impede its movements. When
pure and free from air, when the tube is inclined the mercury
will give a sharp metallic click against the top of the tube.

What are the Vurieties of Barometers ?

1. Cistern barometers—the best form.
2. Siphon barometers.

L’o what Errors ts the Cistern form Liable ?

1. Error of Capillarity.
2. Error of Capavity.

What ts the Error of Capillarity ?

The mercury is depressed in the tube a little below the
true level, and the smaller the tube the greater is this
depression: this is due to capillarity and takes place with
all liquids that po Nor wer the glass; the upper surface of
the mercury too is convex.
40
What is the Error of Capacity ?

It is due to the varying height of the mercury in the
cistern, as the barometer falls the mercury rises in the cistern,
and vice versa; but the height of the barometer is the
distance between the surface of the mercury in the cistern
and the upper surface of the mercury in the tube, and
when the one falls the other rises and wice versa, so that
sometimes the reading is too high, and again at other times
it is too low.

How ts it Corrected ?

By making the cistern as large as possible to REDUCE
the error, or by having a moveable bottom to the cistern,
that can be raised or depressed with a screw, so that before
reading the barometer the level of mercury in the cistern is

always set to zero—the point from which the instrument was
graduated.

Has the Siphon Barometer these Disadvantages ?

No; it has neither the one nor the other.

Then why is it not the Best ?

1. It is necessary always to take two observations—to
read the level at both ends of the tube, and this often results
in mistakes,

2. The open end allows impurities to enter and spoil the
mercury.

Mention other Kinds of Barometers.

The Wheel barometer or weather glass, and the Fitzroy
barometer—both forms of the siphon barometer,
faz +Q+-

LIBRARY,

& -+ Be
41 fe J
4 ~
What is the Aneroid Burometer ? TENE

The principle depends on the varying pressure of the
atmosphere upon an elastic metallic chamber partially
exhausted of air, and then by a series of levers a pointer
is made to travel over a graduated dial.

Ave these to be Trusted ?

No, not for long; they are not so exact as the mercurial
barometers, though they are portable and not liable to be
broken, and are therefore useful for nautical purposes and
for measuring heights.

What is a Vernier ?

It is an instrument for reading off the graduated scale
of the barometer, true to the zj> Or sj part of an inch:
it is named after its inventor—FPeter Vernier.

Explain its Construction and Mode of Use.

It consists of a piece similar to the barometer scale, along
which it slides, but 10 divisions of the Vernier are = 11
divisions of the scale—z.e., to 1,4, of an inch: hence oe

division os the Vernier is = the ,;/5 of an inch a the +5 of
aL: 10 .

& 745 OF quo Or to zoo and zGo—~e., im all 45; so also
two divisions are equal to +42, of a inch or 0:22, and

100
three = 0°33, and so on.

To use it: let the mercury stand between 29 and 30
inches. The Vernier is set so that its zero line forms a
tangent to the convex curve of the mercury in the column.
As this is between 29 and 30, put down 29 as the first

p eer *
@\
4?

figure, next count the tenths from 29 upward, and let the
Vernier indicate more than ;5, but less than 5%, and write
0°7, next find the point at which a division of the scale
of the Vernier and that of the barometer lie in the same :
straight line, say at figure 6 of the Vernier, and this therefore
is = 0:06, so the whole reading is 29°76 inches.

How is Temperature Measured ?

By the thermometer: a closed glass tube with a bulb at
one end and filled with mercury or spirits of wine.

Are Both Equally Useful ?

No: mercury is the best, owing to its uniform expansion
by heat, the readiness with which it indicates changes of
temperature, and the great range of its fluidity, but as it
freezes at 37°9° F. a spirit thermometer must be used to
register the greatest cold.

What are the Vurieties of Thermometers ?

1. Fahrenheit—with the freezing. point at 32° and the
boiling point at 212°: the space between, therefore, being
divided into 180 equal parts. This form is in common use
in England and America.

2. Centigrade (Celsius)—the freezing point is zero and
the boiling point 100°: the scale is therefore divided into 100
equal parts, and hence its name. It is used in France and
most Continental countries, and for scientific purposes.

3. Reaumur’s—freezing point zero, and the boiling point
80°: the scale is thus divided into 80 equal parts. It is
used in Germany and Russia.
43

How would you Convert Fahrenheit into Centigrade, and vice
versa 4
F. to C.—first subtract 32°, then multiply by 5 and divide
by 9.
C. to F.—multiply by 9, divide by 5, and add 32°, because
32° on the Fahrenheit scale is the zero of the Centigrade
scale.

What is meant by Maximum and Minimum Thermometers ?

Thermometers for recording the highest and the lowest
temperature during the twenty-four hours; they are self-
registering : mercury is used for the one, and spirits of wine
for the other. The former records the highest temperature
that occurs during the day; the latter the lowest temperature
that occurs during the night.

What Points are to be attended to in Placing Thermometers ?

They should be protected from the direct and reflected
rays of the sun, and at the same time have a free circulation
of air around them.

How is this Best Done ?

By using Stevenson’s Louvre Boarded Box: the box is
painted white, as this colour absorbs least of the sun’s rays.

At what Height should it be Placed ?

It is set on four posts of such a height that when the
minimum thermometer is hung in its place, it is exactly four
feet from the ground.

What Position should the Box Occupy ?

It should be placed at some distance from walls or other
objects, in an open space, and over old grass to which the
sun has free access during most of the day,
44
Where should tt not be Placed ?

It should not be placed on the north side of walls or
buildings ; nor over black soil—z.e., not covered with grass.

Why ?

The wall acts as a cooler during the day and during
summer, and as a source of heat during the night and during
winter; hence we do not get a sufficiently high day or
summer temperature, nor a sufficiently low night or winter
temperature, so that the daily range of thermometers so
placed is always small. If the box is placed over black
soil, which is more highly heated during the day, and cooled
to a greater degree at night than grass, the maximum
temperature will be too high, and the minimum too low.

How should the Instruments be Read ?

Open the lid of the box, do not touch the instruments,
and first read the dry and wet bulbs of the hygrometer,
so that THEY may not be affected by the heat of the person
standing near.

Then read the minimum, by noting the degree on the
scale at which the end of the index furthest from the bulb
is lying.

Next read the maximum, by noting the degree on the
scale at which the end of the index nearest the bulb is lying
(in Rutherford’s) ; for the others, read the upper level of the
mercurial column. Then set the maximum and minimum
thermometers, and close the box.

What are the Best Hours for Observation ?

For two observations—9 a.m. and 9 p.m.
For four observations—3 a.m., 9 a.m., 3 p.m., and 9 p.m
45

How does Interchange of Temperature among Bodies Take
Place ?

By Conduction, Connection, and Radiation.

What is meant by “Conduction” ?

The communication of heat from particle to particle ;
and it implies close contact with, or very near approach
to, a hotter body.

Give Examples ?
1. Place a poker in the fire, by-and-by the other end will
become hot.

2. The propagation of changes of temperature downwards
through the earth’s crust.

Why does Damp Air Feel Colder than Dry Air of the
same Temperature ?
Because damp air is a much better conducter of heat, and
conveys away the heat from our bodies more rapidly than
dry air, and hence the sense of cold.

Why does a Lump of Marble Feel Colder to the Hand than
a Mass of Wool, at the same Temperature ?

For the same reason; marble is a better conducter
of heat and conveys away the heat from the hand much
faster than the wool does, hence the feeling of greater cold.

Is Snow a Good Conductor ?
No; it is one of the worst.

How is this?

Because it is composed of crystals that have a large
quantity of air entangled among their interstices, just as
loose porous soils full of air are bad conductors.
46
How does Snow Protect the Soil ?

1. It prevents the escape of heat from the earth to the
air.

2. It sets a limit to the depth to which severe frosts
penetrate, thus protecting the roots of the plants.

What is “ Convection” ?

The process by which fluids and gases are heated by
circulation of their particles carrying the heat with them.

Give Examples.

The heating of water in a boiler; when heat is applied
to the bottom of the vessel the particles of water at the
bottom are heated and rendered lighter, and therefore rise
to the surface, while the colder and heavier particles descend.

It is also seen in the winds and in the currents of the
ocean; when the surface is heated by the sun, the air
resting on that surface is heated, becomes lighter, and
ascends, and colder air passes down to take its place.
Under the tropics the air becomes highly heated, and
ascends and flows off towards the poles, while cold currents
flow towards the equator.

What Benefits arise directly from this ?

It secures a more equable distribution of temperature
over the globe, thus mitigating the cold of the polar regions,
and moderating the severe heat of the tropics.

What is Radiant Heat ?

It is heat given out in rays from hotter bodies to colder
ones, and is constantly going on among bodies freely ex-
posed to each other, and tending to bring all bodies to the
same temperature.
47

Give Examples.

The heat derived from an ordinary fire, and felt though
we stand at some distance from it.

What is the Course of the Rays?

They proceed in straight lines in all directions from
their source, and are not diverted from their straight course
by winds; the intensity is proportional to the temperature
of the source, and inversely as the square of the distance
from the source.

What is “Solar Radiation” ?

When the surface of the earth is turned towards the sun
it receives more heat than is radiated from it (the earth) ;
the heat is radiated from the sun, and absorbed by the
earth, into which it passed by conduction.

How does this affect the Temperature of the Atr?

Badly conducting surfaces raise the temperature of the
air over the soil most; hence, a dry sandy soil, devoid of
vegetation, has the greatest effect—e.g., the sandy deserts of
the tropics. Loam, clay, and rock are not heated so high
as sand, and vegetation also protects from the direct rays
of the sun; and, besides, much heat is conveyed away by
evaporation of water from the pores of plants. Vegetation,
therefore, causes a more equal distribution of heat over the
twenty-four hours, lessening the cold of night and the heat
of the day.

What Influence do Forests Exert on Climate ?

Trees store up the heat of the day against the cold of the
night; changes of temperature take place very slowly among
trees; they thus make the nights warmer and the days
colder, giving the climate an InsuLaR character. Forests
also keep the summer temperature lower, and maintain the
winter temperature higher than it would otherwise be.
48
How do Forests Increase the Rainfall ?

In a large forest the temperature is lower than the
surrounding district and affects the rain-bringing winds in
the same way as a low range of hills—z.e., it cools the wind,
and so much therefore of the watery vapour it held in sus-
pension is thrown down as rain.

What is meant by the “ Specific Heat” of a Substance ?
The number of units of heat that is required to raise the
temperature of one pound of it by one degree.

What is the Specific Heat of Waiter?

Of all known substances it has the greatest specific heat :
for example the amount of heat necessary to raise one
pound of water 1° will raise one pound of mercury 33° ;
as compared too with the soil and the rocks of the earth’s
crust, water is in the proportion of about 4 to 1.

What is the Natural Consequence of this ?

The surface of the sea cannot be raised to nearly the
same degree of heat by the sun’s rays as the surface of the
land, and when the temperature is falling the sea cools much
more slowly than the land. The surface of the land may
be as high as 140°, but the surface of the sea rarely ever
exceeds 85°,

Name Another Result of this Fact ?

It is the cause of land and sea breezes, as the land is
much more heated, and cools much more rapidly than the
sea. In the morning a breeze sets in from the sea very
gently at first, and increases to a stiff breeze in the heat of
the day, and again sinks to a calm towards evening; after
this a breeze begins to blow off the land during the night
and dies away in the morning. It is due to the general fact
49

that the wind blows from a region of higher to one of lower
pressure ; now the land is heated toa much greater degree
than the sea during the day, by which the air resting on it,
being also heated, ascends, and the cooler air of the sea
breeze flows in to supply its place; but during the night
the temperature of the land falls below that of the sea and
the colder and denser land air flows away over the sea as 4
land-breeze.

How is the Surface Temperature of the Land Measured ?

By a maximum black-bulb thermometer, in an ordinary
maximum thermometer having its bulb covered with a thin
coating of lamp black.

How ts it Placed ?

It should be placed horizontally over short grass, so near
the ground as just to. be above the grass, and in such a
position that the sun may shine directly on the bulb for
as large a portion of the day as possible. It should point
directly to the sun at twelve o’clock.

How does the Surface of the Earth Cool during the Night?

It cools by radiating the heat it had absorbed from the
sun’s rays during the day into space: this is called terrestrial
radiation.

Why is a Cloudy Night Warmer than a Clear One?

When the sky is covered with clouds a large portion of
the heat radiated from the earth to the clouds is radiated
back again by the clouds to the earth, and hence the
- temperature does not fall so far or so fast: this is because
water vapour is a bad conductor. Also when the air is
saturated with watery vapour the night is warmer: the drier

the air the colder the night.
D
50
What Effect has the Deposition of Dew on the Temperature ?

It should raise the temperature as long as the dew is
falling, because in passing from a state of vapour to the
liquid state latent heat is given out.

How is the Cold of Radiation Measured ?

By means of the minimum black-bulb thermometer in
an ordinary minimum thermometer, with its bulb blackened.
It should be placed like the maximum black-bulb ther-
mometer.

What is Dew and How is tt Formed ?

It is the watery vapour of the atmosphere condensed into
visible drops, and takes place when the air is cooled below
the temperature at which it is able to hold the watery vapour
present in suspension. The hotter the air, the more watery
vapour is it able to hold in suspension; but during the
night, as the earth cools by radiation, the layer of air next
its surface is cooled below the point at which it can hold
the vapour present in suspension, and the excess is therefore
deposited as “dew.” The same phenomena is seen when
a glass of cold water is left for a little while in a crowded
room; and the moisture on the walls and window panes of
crowded rooms is due to the same cause. The quantity
of dew deposited depends on the degree of cold produced,
and the amount of watery vapour in the air.

What other Conditions affect its Formation ?

It is not deposited in cloudy weather because the clouds
prevent the loss of heat by radiation, nor in windy weather,
because the wind constantly renews the air in contact with
the ground and thus prevents the temperature from falling
sufficiently low. It is rarely deposited on the surface of
51

deep water, because the temperature of water falls so slowly
and is hardly ever low enough, as the cold water sinks, and
hot comes to the surface in its place.

What is Hoar Frost ?

It is dew deposited when the temperature is below the
freezing point, or rather, it freezes as it is deposited—frozen
dew.

What Effects are Produced by Lakes on Climate ?

If the lake is too deep to freeze then it renders the winter
more mild on its shores, and also modifies the excessive
heat of summer. If, however, the lakes are frozen it does
not modify the severe cold of winter, though it tempers the
summer heat: it is thus in North America where the large
lakes are frozen over, and here, therefore, there is a very
severe winter and a summer of insular coolness, The sea
also modifies the climate as it is very rarely frozen over.

What Effect do Forests Exert ?

The temperature is warmer at the base of a mountain and
up its sides when the slopes above are covered with trees.

How is this?

(1) The trees lessen radiation from the surface they cover,
and (2) they tend to stop the passage of descending currents
of cold air.

What is the Importance of this Fact ?

It is important for invalids, as it has been shown that
when the temperature falls beyond a certain point the death-
rate rises in the same proportion.
52
What is the Best Position for a Dwelling ?

Dwellings best protected from severe cold are those
situated on a gentle slope a little above the plain or valley
from which it rises, having a southern exposure, and the
ground behind planted with trees; sleeping rooms to be in
the higher flats, as at a little height from the ground the
night temperature may be many degrees higher than what
prevails near the ground. In camping out, for example, the
tent should be placed on a rising knoll or other eminence,
as the temperature is higher there than in hollows, even
though close at hand; this is shown by the natural choice
of resting ground at night by cattle and sheep, who select
the higher ground, in preference to hollows.

What is the “ Gulf Stream” ?

It is a great ocean current that starts from the Strait
of Florida, and flows northwards— or rather in a north-
easterly direction — forming the chief part of the North
Atlantic Ocean. It is much warmer than the rest of the
ocean near it.

What is the Effect of this Great Current ?

It has a most beneficial effect in modifying the rigors
of our northern water ; it raises the temperature of Shetland
39°, and of London 21° above what would probably other- .
wise be their winter temperature—Shetland 3° and London
17°. It also makes the west coast of the British Islands
warmer than the east coast, and the heat of the West
Coast increases as we pass southwards, while the tempera-
ture of the east is the same all over. The temperature of
the south-west of England and Ireland are 40° higher than
the west coast of Scotland. This explains the value of the
Isle of Wight as a water resort to those who require a mild
winter climate; but the south-west of England and Iveland
are also good,
53
What ts the Effect of Mountain Ranges on Temperature ?

Mountain chains deprive the winds that blow over them
of their moisture, and thus cause colder winters and hotter
summers in places to the leeward, as compared with places
to the windward, as they thus remove the protecting watery
vapour, and expose them more fully to the effects of solar
and terrestrial radiation.

Give Examples.

Norway and Sweden abroad; and at home, the east and
west coasts. For the same reasons the rainfall on the side
turned towards the prevailing wind is more rainy than the
other—e.g., the west coast is more rainy than the east coast.

What ts meant by “ Isothermal Lines” ?

They are lines on a map or chart drawn through all places
having the same mean annual temperature.

What other Lines are there like these ?

1. Isochemals, or lines of equal WintER temperature.
2. Isotherals, or lines of equal SumMER temperature,

What are ‘ Isobarie Lines” ?

They are lines on a map or chart drawn through all places
having the same mean atmospheric pressure, as shown by
the barometer.

What is the Hygrometer ?

It is the instrument for ascertaining the amount of
watery vapour in the atmosphere.
54

Name some of the Varieties.

1. The Harr Hycromurer of Saussure. The hair is
attached to a lever, and when the air is damp it absorbs
moisture, and becomes shorter. Its principle is absorption :
it is also called called a Hygroscope.

2, Danrett’s and Recnauti’s HyGRomETers, condensing
hygrometer or dew point instruments.

3. The usual method is by the Drv anp Wer Burs
THERMomETERS, a hygrometer of evaporation, also called a
psychrometer.

What would be the Result if the Air were perfectly free from
Watery Vapour ?

The air would permit the sun’s rays to pass through it
unimpeded, so that during the day the sun would burn up
everything, and then at night the radiation from the surface
of the earth would be so free and rapid that everything
would be destroyed by intense cold. The air, in fact, would
be perfectly transparent to the rays of heat—p1aTHERMANOUS.

Where is this Observed to a Limited Extent ?

On very high mountains—e.g., the Alps, where the sun
is scorching during the day, and the cold very intense at
night. It is also observed in the polar regions to a certain
extent, where the pitch on the side of the ship next the sun —
may be melted, while ice is forming on the other side—the
side away from the sun, and therefore in the shade.

What are the Kinds of Clouds ?

The simple varieties are—
1. Cirrus (crrrus, a curl).
2, Cumulus (cumuLus, a heap) —the cloud of the
day.
55

3. Stratus (stratus, spread or laid or a layer)—the
cloud of the night.

Two or more of the above may be combined in varying
proportions, and are named accordingly—e.g., Nimbus or the

. yain cloud is cumulo-cirro-stratus.

How is the Rain-Fall Estimated ?

By means of a rain-caucr. The simplest form consists
of a funnel opening into a receiver in which the rain is
collected, and from which it can be withdrawn and measured:
the funnel catches the rain, and also prevents evaporation,
but its rim must be truly horizontal, or else it will catch too
much or too little, according to the direction and force of
the wind. .

* How is the Gauge to be Placed?

It should be placed at least six inches from the ground
to avoid splashing, and in the centre of a level open plot;
the nearer the earth it is the more it catches.

Give a few Mean Annual Rainfalls.

Edinburgh and London, 24 inches.
Liverpool and Manchester, 35 to 36 inches,
Dublin, - - - 30 inches.
Glasgow, - - - 40 inches.

What is a Rainy Day?
A fall of rain equal to ‘01 or zg, of an inch.

How is the Velocity of the Wind Measured ?

Usually by the Hemispherical-Cup Anemometer (Robin-
son’s Anemometer). It consists of four hollow hemispheres
or cups screwed on to the ends of two horizontal rods
crossing each other at right angles, and supported on a
56

vertical axis which turns freely. When placed in the wind
the cups revolve like a wind-mill, and the arms are of such
a length that when a mile of wind has passed the ane-
mometer, 500 revolutions are registered on the dial of the
instrument.

How is the Force of the Wind Measured ?

By means of a water monometer.

What ts the Cause of the Discomfort Produced by the “ East
Wind” ?

It is because they are so very dry and cold, and a wind
of this character, wherever it comes from, is always as
injurious to animals and plants as the true “east winds :”
they probably come from Siberia, in Russia.

What are the Causes of the Winds?

1. Unequal atmospheric pressure: winds blow from a
region of a higher to a region of lower pressure: hot air
is lighter and ascends, and the cold rushes in to take its
place; hence differences in temperature at different parts
of the globe is probably one of the most important causes
of the wind.

2. Another equally important cause of a lowering of
atmospheric pressure is the presence of an excessive amount
of moisture or aqueous vapour in the atmosphere.

3. A third cause is the rotation of the earth.

 

Edinburgh : Printed by E, & S. Livinastonr, 4 Melbourne Place.
 

CATECHISM SERIES.

PUBLIC HEALTH:

MEDICINE. FOOD. BURIAL.
WATER-CLOSETS. DISINFECTANTS.
WARMING. HOSPITALS.

7

EDINBURGH:
E. @ SS. LIVINGSTONE,

1802.
C236)

PRINTED BY
E. & 8S. LIVINGSTONE

4 MELBOURNE PLACE
EDINBURGH
PUBLIC HEALTH.

—@_-

MEDICINE.
What is “ Endemic” ?

Diseases that are more or less limited to certain geographical
areas, and always more or less present among the inhabitants
of these areas, are said to be ‘‘ ENDEMIC” to these localities.

Give Examples ?

Yellow Fever in the West Indies.
Cholera in India.
Ague in Essex.

What is “ Epidemic” ?
When a disease spreads rapidly so as to incapacitate and
destroy great numbers of the people, it is said to be “‘ epidemic.”

What is “Pandemic” ?

Diseases that have no special local habitat—e.g., small-pox,
measles, ete.

How is Cholera Propagated ?

By the so-called epidemic influences. By infection in the
matters discharged by purging and vomiting ; these matters are
not infective as discharged, but soon ferment and rapidly
become dangerous, and so they should be rapidly disinfected ;
4

the specific poison is very dangerous if in a large volume of
water. Clothes, ete. soiled with cholera discharges, if not
disinfected, long retain their power of infection, and should
therefore always be disinfected at once.

What ts the Cause of Cholera ?

A specific micro-organism or poison, whose manifestations
depend chiefly on local and meteorological circumstances. Its
development is favoured by high temperature, stagnant atmos-
phere, and moisture—z.e., still, close, and hot. Impure water,
low sites, and emanations arising from decomposing animal
refuse and fermenting excrement. A Hwavy rainfall may check
its spread by diluting and washing it away, and by cleansing
the streets and sewers: a LIGHT and intermittent rainfall favours
its spread.

What Precautions should be Taken against the Spread of
Cholera ?

The dangers which have to be guarded against as favouring
the spread of cholera-infection are particularly two. First, and
above all, there is the danger of waTER supPPLIEs which are in
any (even the slightest) degree tainted by house refuse or other
like kind of filth; as where there is outflow, leakage, or
filtration, from sewers, house-drains, privies, cesspools, foul
ditches, or the like, into springs, streams, wells, or reservoirs,
from which the supply of water is drawn, or into the soil in
which the wells are situate—a danger which may exist on a
small scale (but perhaps often repeated in the same district) at
the pump or dip-well of a private house, or, on a large or even
vast scale, in the source of public water-works. And secondly,
there is the danger of breathing air which is foul with effluvia
from the same sorts of impurity, and for this reason—

(1) Immediate and searching examination of sources of
water supply should be made in all cases where the source is

 
5 ‘

in any degree open to the suspicion of impurity; and the
water both from public and private sources should be examined.
Where pollution is discovered, everything practicable should
be done to prevent the pollution from continuing, or, if this
object cannot be obtained, to prevent the water from being
drunk. Cisterns should be cleaned, and any connections of
waste-pipes with drains should be severed.

(2) Simultaneously, there should be immediate thorough
removal of every sort of house-refuse and other filth which
has accumulated in neglected places; future accumulations
of the same sort should be prevented; attention should be
given to all defects of house-drains and sinks through which
offensive smells are let into houses; and thorough washing
and lime-washing of uncleanly premises, especially of such as
are densely occupied, should be practised again and again.

Also, see that all choleraic discharges, whether by vomiting
or purging, are at once disinfected before they are cast into the
water-closet, etc. That all clothes, etc., imbued with the dis-
charges are at once disinfected ; and lastly, see that there is
no leakage from cesspools or drains into wells or other sources
of drinking water.

What Remedies are Suitable for an Epidemic of Cholera ?

1, Elixir of vitriol.

2. Lead and opium pill, with capsicum.

3. Aromatic powder of chalk and opium—for children and
young persons.

4, Ordinary mustard.

During a threatened epidemic of cholera, all diarrhea and
looseness of the bowels should be checked at once—

(1) By causing persons affected with looseness of the bowels,
who are usually very thirsty, to drink freely of cold water, to
which elixir of vitriol has been added in the proportion of half
a tea-spoonful of elixir to a tumbler of water.
6

(2) Should the diarrhoea, in spite of the above treatment,
continue for (say) two hours, a lead and opium pill should be
given, and the dose should be repeated after every loose motion.
If the patient, from weakness, be unable to follow his usual
employment, he should be put to bed—care being taken that
the limbs are kept warm, and that the bed is kept dry by means
of a sheet of oil-cloth, gutta-percha, or Macintosh between the
sheet and the mattress.

What further Treatment should be Adopted ?

Should the discharge from the bowels present the appear-
ance of water, and should there be urgent vomiting, cramps of
the limbs, together with general sinking or collapse, the case
should be regarded as most serious, and in the absence of a
medical man, mustard poultices should be applied to the belly
and chest for half-an-hour at a time, and should be followed
either by fomentations with warm water, or by bran or porridge
poultices on the same parts of the body. These mustard and
soft poultices should be alternated from time to time. Mean-
while the limbs should be well rubbed with warm cloths, and
the lead and opium pills regularly administered, as directed
above. This treatment may be advantageously employed for all
persons above 15 years of age. From 10 to 15 years the only
change recommended in the treatment is that half a lead and
and opium pill, instead of an entire pill, should be given as a
dose. Below 10 years of age, the aromatic powder of chalk
and opium should be substituted for the pill, and may be
administered in doses of one grain for each year of life. Thus,
an infant of one year should have one grain for a dose; and
under one year, half a grain; while a child of six years should
have six grains. The treatment otherwise is the same—care,
however, being taken in the case of children not to allow
the mustard to remain beyond TEN MINUTES in contact with
the skin.

Nore—(1) That persons in ordinary health, not affected
with looseness of the bowels, and who are careful to avoid
7

excesses of all kinds and to attend to daily ablution of the body,
can act as nurses without any great risk.

(2) That should cholera visit this country, no class of the
community is more likely to furnish victims to the disease, and
to carry it over the country, than tramps or beggars—it being
well known that want of food, scanty clothing, and exposure
to the inclemency of the weather, predispose the body to the
infection of cholera.

(3) That the prompt administration of medicines checks
the premonitory diarrhoea, and prevents the development of
the disease,

Hence the importance—(a) of attending to the condition
of all tramps and of the poorer population of the country
generally, and of seeing that they are supplied with the
necessaries of life; (6) by means of house-to-house visitation,
of ascertaining the state of the general health of the district,
and specially the existence of diarrhcea ; and (c) of supplying
suitable remedies for this most important premonitory symptom.

What ts Known about the Origin of Typhoid Fever ?

It is a filth disease, and usually arises by poisoning of the
air or water, or other ingesta, by decomposing filth; most
frequently it is the water from soakage of sewage into it. The
bowel discharges possess the specific infection in a very marked
degree.

What Points should be Attended to on an Outbreak of Typhoid ?

Disinfect at once all the evacuations before they are poured
out into the water-closet. Examine the water supply, the
drains and sewers, water-closets, especially the traps, close
polluted wells, and clean out and disinfect filthy privies. If
proper precautions are taken as to cubic space, ventilation, rest
and food, and general cleanliness, there is but little danger to
nurse or attendants either in this fever or in cholera.
8
What Conditions Generate and Spread Typhus Fever ?

Overcrowding (ocutests), deficient ventilation, clothing satu-
rated with cutaneous exhalations, squalor, dirt, and want ; and
a low state of the system, favoured by a moderate temperature.
The cutaneous and respiratory exhalations contain and convey
the infection; the air is contaminated and attaches itself to
and soaks into the walls, furniture, bedding, clothing, etc. It
does not, however, travel far through the air ; and if the room
is well-ventilated, the attendants run but little risk, and other
occupants none whatever. It requires close approach to, and
contact with the infected person and his dirty belongings, for
some time, to be infected. The poison rises to upper storeys,
and is kept especially by dark-coloured woollen things.

When is the Infection Strongest ?

From the end of the first week up to convalescence—just
when the smell from the skin and lungs is the strongest.

What other Names has this Fever ?

Jail fever, Ship fever, Camp fever, Hospital fever, Ochlotic
fever. It is also one form of ‘Brain fever,” so called because
of the frequency of cerebral complications.

What Precautions should be Adopted in a Case of this Fever ?

- Isolate the sick.

. Attendants should have had the disease.

. Visitors must avoid cLosz contact.

The room must be well ventilated by fires and windows.
. All useless furniture, carpets, and curtains removed.

. A free supply and free use of disinfectants in the room.

. Bedding and clothing disinfected or destroyed.

8, After convalescence, every piece of furniture, and the
whole room should be purified.

Noarwhr
Is Smaill-Pox Infectious ?

Yes, very; there is no contagion so strong and sure, and
none that operates at so great a distance. It is wafted from
house to house at opposite sides of the street, and from small-
pox hospitals. The poison is given off from the skin and
mucous surfaces of the patient; it is found in the exhalations,
excretions, secretions, and in the matter in the vesicles, pustules,
and scabs. It is volatile and contaminates the air, like typhus,
and is of very great vitality.

What Precautions should be Taken on the Outbreak of Small-
Pou?

1, Immediate and complete isolation of the infected person,
to a tent or shed.

2, Vaccinate those not already vaccinated, and re-vaccinate
those already vaccinated.

3. Careful disinfection of the house by sulphurous acid, and
destruction of all infected bedding, clothing, etc.

When is the Person Free from Infection ?

Not till all the crusts have fallen off and the scars all healed ;
the body sponged with water and some disinfectant, and bathed
several times.

What is Anown about the Poison of Scarlet Fever?

It specially attacks children between three and four years
“of age: the specific poison is very powerful and volatile, so that
persons should not remain long in the same room or house
unless protected, and the ventilation is very good and the
cubic space large. The poison is contained in everything that
proceeds irom the patient, especially the scales from the
skin, which are carried into the air and settle on clothing,
furniture, etc.
10

When ts the Patient Free from Infection ?

Not till the desquamation is complete and the surface of the
body well bathed and anointed with some disinfectant ointment:
desquamation is not usually compete till eight or ten weeks
after the beginning of the fever.

What is Known about the Poison of Diphtheria ?

It is said to be very often associated with sanitary defects—
though probably follicular tonsillitis is often mistaken for it:
also with polluted drinking water, and foul effluvia from drains,
cesspools, etc., and also with damp dwellings. It is most
common in rural districts, and usually prevails among children
and young adolescents. "When developed, the poison spreads
from the throat and breath, the excretions through sewers and
water-closets. Kissing or inhaling the breath of the infected
person is bad and often fatal. It is conveyed through clothing,
milk, the agency of schools, especially from children. The
Sanitary Authority, however, has power to close schools in
epidemics of diphtheria. In children, it is most often fatal by
closing up the chink of the glottis; in adults, from asthenia

and cardiac paralysis. ;

Give a Short Sketch of the Hygienic Treatment of Phthisis ?

1. Plenty of pure fresh air.

2. Gentle exercise in the open air daily.

3. A high, dry, and equable climate, even though cold, as
phthisis is most common in low-lying damp places, but is not
a disease of the Arctic regions. High winds shuuld be avoided:
a temperature of about 60° F. is the best.

4, Careful and proper dress.

5. Rest from sunset to sunrise.
6. Outdoor work in fresh air.
7. Cleanliness of body.
11
Under what Conditions does the Malarial Poison Arise ?

From decomposition of vegetable matters under PARTIAL
moisture, with a temperature above 60° F. If the marsh be
perfectly dry or flooded, the poison is not developed: it is
carried great distances by the wind and is most intense near
the ground. <A belt of trees may prevent the spread, and it has
almost disappeared from improved drainage.

Give a Short Historical Sketch of Typhus Fever ?

It was first known as the ‘Black Assizes,” Old Bailey, in
1756, where Judges and Jurors died, infected by the prisoners ;
hence, it was called “Jail fever.” It has been the great scourge
of armies in temperate climates, just as cholera and yellow fever
are in the tropics. It arises wherever persons are crowded
together in ill-ventilated and unwholesome dwellings. In
1489, 17,000 of the troops of Ferdinand besieging Granada
were destroyed by it. So also in the army of Charles V. during
the siege of Metz; and in 1556, in the army of Maxmillian IT.
in Hungary, and from this spread over all Europe. In 1620,
the Bavarian army lost 20,000 by it in a few months, and again
a large number in 1812-13. In the spring of 1856, in the
Crimean war, 17,000 of the French perished in three months,

How does Relapsing Fever Arise ?

Usually from poverty and exhaustion following on long
continued privation, together with overcrowding, poverty, and
destitution ; hence, it is called “famine fever” or “hunger pest.”
A spirillum is found in the blood, the sPIROCHETHZ OBERMERII.
It resembles ague in its relapses and enlarged spleen but has
no relation to the season of the year.

Give some Examples.

It spread in various parts of Scotland in 1817-18: the
Edinburgh and Leith epidemic in 1843: in the summer of
12

1855, after the hardships of the preceding winter, it spread
among the British troops in the Crimea: it also spread in
America from the Irish emigrants, but since then it seems to
have died out.

What is the Origin of Yellow Fever ?

It is usually limited to 40° N. latitude and 20° S. latitude,
and a temperature of 72° F. at least. It is usually endemic
in low districts on the sea-coast, and rarely occurs above 2500
feet above the sea level. It seems to be due to the accumula-
tion of fecal excreta round dwellings and to overcrowding.

It is characterised by “black vomit,” black stools, slow and
intermittent pulse: the black vomit and stools are probably
due to hemorrhage: the urine is often suppressed. The black
vomit is very acid and contains ammonia combined with some
substance ; caustic potash dissolves the sediment and sets the
ammonia free : the source of the ammonia is probably used for
the suppression of urine.

How does Yellow Fever differ from Malarious Fevers?

In Manarta—

. Quinine has a marked effect.

. The spleen is enlarged and softened.
. There is no albumen in the urine.

. The death-rate is small.

There is an absence of hemorrhages.

. There is no black vomit, nor marked yellowness
of the skin,

7. One attack does not confer immunity from another,
The reverse obtains in Yellow Fever.
In Yettow Frever—
1. It requires a higher temperature, 72° to 77° F.
2. The urine is albuminous.
3. The fever is continuous, not remittent.

The fever is carried about in ships, by the cargo, sailors, etc,

QD oR oo DH
15
What is the Cause of Malarial Fever ?

The poison is aerial and is exhaled from marshes or wet
ground loaded with decomposing vegetable matters, especially
when the ground is in the process of drying. It arises from
low swampy, humid and hot parts; the banks of rivers and
lakes, shores of great seas where the water flows slowly and
sometimes stagnates, where the vegetation is vigorous and where
amphibia abound, and rich soil imperfectly cultivated with
decaying vegetable and animal matters.

The poison requires a certain temperature to develop: it
varies also with season and with geographical position, as after
the rainy season when the loch is drying up, especially in low
swampy places, and extensive rice fields. 100 years ago it
was common enough in London. Ground alternately moistured
and then dried by the pirect rays of the sun is worst. Natives
of warm countries are less liable to be attacked by the poison,
new-comers most. The poison is most active at night, but spreads
along close to the ground in the direction of the wind: groves
of trees and running water check the spread of the poison.

What Precautions should be Adopted in Malarious Districts
Sor New-Comers ?

They should as far as possible adopt the habits of the natives:
take a daily dose of quinine: should not remain out long at
night, and sleep in the upper storeys of houses, or, failing that,
in trees; and should not on any account rest near the soil.
Fowler’s solution (“‘ague drop”) is useful as a prophylaxis or
curative agent.

What is Known respecting the Cause of Dysentery ?

It has followed the track of all large armies for the last 200
years, and prevails in besieged garrisons and in barren encamp-
ments. In countries where malaria exists it is always found
endemic and prevailing, as the East and West Indies, China,
14

Gibraltar, Coast of Africa, and the Eastern parts of Great
Britain. The night air, wet, fatigue, and all causes of privation
and bad hygiene predispose to it.

What is “ Glanders” and ‘“‘ Farcy” ?

Guanpers is characterised by congestion of the nasal mucous
membrane, with glutinous secretion and the presence of soft-
chancre-like sores ; the disease spreads into the various sinuses
connected with the nasal cavities, as the frontal, ethmoid, and
sphenoid, and also to the trachea and bronchi. There are also
pustular eruptions on the skin, like small-pox or ecthyma,
followed by suppuration or gangrenous ulceration of various
parts. One or other of the above may alone be present, or
they may be combined. Besides this, there is fever of a low
and malignant type.

Farcy is a general inflamation of the lymphatic glands and
vessels, as well as the tissue around, forming “farcy buds”
or ‘‘buttons”; these suppurate and secrete a specific virus.
“Button” farcy is limited to the glands and vessels. It will
be seen, therefore, that “‘glanders” affects the nasal passages
chiefly, whereas ‘“‘farcy” affects the lymphatics; but glanders
may produce farcy, and vice versa.

How does this Disease Originate ?

It arises in the horse, ass, or mule; in the horse, from bad
ventilation—e.g., on board ship, from dirty close stables, bad
food, and severe weather. It is contagious, and the affected
animal must be killed, and all animals touched by the disease.
It is spread by drinking from the same pail, or from licking the
rack, etc.

For those attending to horses, it is necessary to avoid contact
with the secretions of the mucous membrane, especially if there
is an abrasion ; if and abrasion is inoculated, it must be destroyed
by potassa fusa.
15
What ts Splenic Fever ?

It is a disease that is found among horned cattle, sheep, and
horses, and in a few others.

What other Names are Applied to it ?

In England it is called splenic fever or apoplexy, joint
murrain, black quarter evil, the “blood”: braxy (in sheep),
anthrax, and Siberian plague (in horses).

In Germany, it is known as Miltzbrand and anthrax.

In Frauce, it is called charbon, sang de rate, and mal de rate.

Does the Disease Occur in Man ?

Yes ; it occurs in man by direct contagion from animals.

What are its Varieties ?

1. External local form—“ malignant pustule.”

2. Internal form, with various names, as—
(1) Mycosis intestinalis (German).
(2) Hair-comber’s disease.
(3) Wool-sorter’s disease.
(4) And one form of Rag-sorter’s disease.

What are the Appearances in Cattle ?

The spleen is enlarged and swollen, and looks as if filled
with a blood clot—hence the name ‘splenic apoplexy ;” there
are also hemorrhages in internal organs, as the lungs, walls
of heart, kidney, and brain. There are glandular swellings in
the neck and mediastinum, especially in sheep, and effusion
into serous cavities. In the blood, large numbers of bacteria
are found—the BacILLUS aNTHRACIS, which is believed to be
the cause of the disease: they are found chiefly in internal
organs, especially the lungs, where the capillaries are crammed

full.
16
What do you Know about this Organism ?

It requires oxygen for its growth; this it takes from the red
blood corpuscles. Continued dryness kills; 8 atmospheres
of oxygen will also kill: freezing does not kill, but the
bacterium termo of decomposing fluids kills it. It multiplies
by spore formation.

What is Malignant Pustule” ?

The external local form of anthrax in man; it is a specific
septic form of gangrene. It is produced by contagion from
animals, and from the hides, hoofs, and hair of animals dying
from this disease.

It may arise—

1. From direct inoculation, as in butchers and farriers.

2. From hair, skins, wool, etc., as in hair-sorters, rag-
pickers, wool-sorters, upholsterers, etc.

3. From eating the flesh, milk, or butter of the affected
animals—very doubtful ‘‘braxy” sheep are constantly eaten
in the country at the farms where the sheep die, and are
exceedingly nice.

4. It may be carried and implanted on the exposed parts
of the body by bites of flies, ete.

What ts the Appearance of the Sore?

It is found on the exposed parts of the body, as the face,
neck, hands, and arms. It is at first a small hard pimple, red
and angry looking, with a red areola round it, like the bite
of a gnat; a little vesicle forms, and the part becomes
gangrenous, forming a hard, black, depressed eschar, with a
crop of vesicles round it; the spreading edge of the sore is
raised, though the gangrenous part is depressed. Beyond the
vesicles is a red erysipelatous-like blush. The tissues are full
of the bacillus, the lymphatics are inflamed and enlarged, and
death occurs from septic poisoning, or it may pass into some
of the internal organs.
17
Why is it Called a “ Pustule” ?

Because it never contains pus. This is of great importance
in diagnosis, as this gangrenous part when cut into does Nor
contain pus.

What are the Features of the Internal Forms ?

The lesion occurs in the alimentary canal and the respiratory
tract. The bronchial and mediastinal glands are swollen: there
may also be hemorrhage in the lungs and brain, mediastinal
cellulitis, pleural effusion. The mucous membrane of the
trachea and bronchi are swollen and infiltrated with bacilli—
in the tissues and lymphatics, not in the blood-vessels.

Note,—Typhoid fever is endemic.
Typhus is endemic and infectious.
Relapsing fever is epidemic and infectious.
Typhus is endemic in Ireland. ‘he poison of this fever
is lighter than the air, and therefore rises to the highest parts
of the wards, top rooms of houses, etc.
Typhoid is chiefly endemic in the British Isles, being—
Most in England,
Next in Ireland, and
Last in Scotland.
It is most frequent in autumn and the end of summer.
Typhoid occurs in the mansion: typhus and relapsing fever
in the hovel.
Relapsing fever is endemic in Ireland, and in Upper Silesia
(which resembles Ireland), inhabited by Poles.
Great cause—“ Penury pent up in airless dwellings.”
Typhus occurs in Winter and Spring.
Typhoid occurs in Autumn.
Relapsing fever is independent of season.
Typhus is most fatal at the onset of the epidemic.
Typhoid increases with the continuence, and is therefore

worse towards the end, of the epidemic.
B
18

FOOD.

What is the Composition of the Human Body ?

Albumen, 90:4 oS:
Fatty matters, 2°5 \ sane

Inorganic substances { ae . t = 768

100°0

Organised substances {

What amount of Nitrogen and Carbon does the Body Require in
Twenty-four Hours ?

300 grains of Nitrogen.
4800 grains of Carbon.
Or in the proportion of one of nitrogen to 16 of carbon.

What is the Ratio of these Elements in Albumen and Bread
respectively ?

In Albumen the ratio is one of nitrogen to 3°5 of carbon.
In Bread it is one of nitrogen to 30 of carbon.

What would be the Result of Living on Either Alone ?

On Albumen alone there would be a great waste of nitrogen ;
because to get the carbon we would have to take 7547 grains,
and this contains 1132 grains of nitrogen, or almost four times
too much. The result uf this is that there is a great deal of
profitless labour thrown on the excretory organs, in order to
get rid of the excess, injuring the kidneys, and inducing the
uric acid diathesis.
19

If one live on Bread alone, there is a great waste of carbon ;
for in order to get enough nitrogen we must take 9000 grains
of carbon, which is double the amount required: hence, the
necessity for a mixed diet.

Tn order to get 4000 grains of carbon from meat, we would
require to eat four pounds of fatless meat, whereas three-quarters
of a pound will yield 300 grains of nitrogen—e.g., two pounds
of bread and three-quarters of a pound of meat, with a little
dripping or butter, will give the proper amount of carbon and
nitrogen without waste.

What is the Weight of a Full-Grown Man?

About 154 lbs: consisting of—

88 lbs. of water, and
66 lbs. of solid matters.

What are the Gains and Losses of such a Body ?

 

 

Gain per day— riers
Solid dry food, = - - - 8000
Oxygen, - - - - 10,000
Water, - - - - 36,500

54,500

Loss per day— GRAINS.

Water, - - - - 40,000
Other matters, - - - 14,500
54,500

What Amount of Work should such a Body Perform ?

From 340 to 450 foot-tons—.e., to lift this number of tons
one foot high or its equivalent.
20
Give a Diet Table for Ordinury Work ?

OUNCES. GRAMMES. GRAINS.
Proteids, 45 or 130 or 2000
Amyloids, 14:2° or 404 or 4400
Fats, 3°0 or 84 or 1200
Salts, 1-0 or 30 or 400
Water, 36,500
22-7 44,500

It will be seén that about 23 ounces of solid dry food is
required, one-fifth of which is nitrogenous; half the ordinary
food is water, so that this will correspond to 46 ounces of
ordinary water, leaving 50 to 80 ounces of water to be taken by
other means.

The force-producing value of the diet is nearly 4000 foot-
tons.

The feeces passed per day, after such a diet, would amount
to about 2800 grains, containing about 800 grains of solid
matters.

Give a Diet for Idleness ?

OUNCES,

Proteids, - - - - 25
Fats, - - - - 1:0
Carbo-hydrates, - - 12:0
Salts, 2 eas 7 0-5

Water as before.

Give a Hard Work Diet ?

OUNCES.
Proteids, - - - - 6 to 7
Fats, - - - - 3°59 to 46
Carbo-hydrates, - - 18 to 22
Salts, - - - oe 12to 15

Water, ad libitum.

One hundred persons excrete daily 71:5 Ibs. of carbon and
4°5 lbs. of nitrogen : to make good this waste in a cheap manner,
21

say in a prison, give bread and water; but this is wasteful
of carbon, since we would require 380 lbs. of bread to give
sufficient nitrogen, but in this there is 128°5 lbs. of carbon, or
57 Ibs. too much. If we use purely animal diet we would
require 354 lbs. of lean meat to get enough of carbon ; but this
amount of lean meat contains 110 Ibs. of nitrogen, or 105 lbs.
too much. This also would be wasteful, besides injuring the
person’s health.

What is the Proper Proportion to Use?

For one hundred persons, as above, use—

200 Ibs. of bread.
60 Ibs. of meat, since—

CARBON. NITROGEN.
200 Ibs. of bread contains” - - 60 2
60 Ibs. of meat contains = - - 12 24

Total, 72 Ibs. “44 lbs.

This is just sufficient to make up for the loss, but more
would be given in actual practice to have a margin for
emergencies. It would also depend on the work done by the
prisoner. The work done by the body is reckoned as equivalent
to raiSing a man of 10 stones through 10,000 feet: in penal
service, one-half more is added to this—z.e., to raise 10 stones
through 15,000 feet.

Nore—10,000 feet is about equal to 34 miles.

In what Ways can the Energy for this be Obtained, or at what
Expense ?
Say—
3'5 lbs. of lean meat, cost 3s. 6d.
One-half Ib. suet, cost 54d.
Three quarts of milk, cost 6d.

Cheese, say 10d. worth, is as good as the
3°5 lbs. of meat.
22

Other methods would be by using nS and bacon, or
apples and cheese.

One hundred prisoners at hard labour would require—
58 lbs. of bread,
54 Ibs. lean meat, and
_ 63 Ibs. of potatoes.
This would be just ENovcH for the needs of the body and

for the work done; but it*would be advisable to add to this
some milk or porridge.

Hew do you judge if the Diet be Suficient—e.g., in Prisons ?

By the patient’s general health, and by weighing him care-
fully every week, so as to see whether he is gaining or losing
weight.

What Purposes do the various Food-Stuffs Serve ?

The Prorsips determine the absorption of oxygen and build
up and repair tissues, The Fats and Carpo-aypratss are the
great and direct sources of energy. The Sars determine
osmosis and nutritive tissue changes,

Give Examples of the Food Stuffs.

1. Proterps, as—
Albumen, as in eggs and meat.
Casein, in milk.
Myosin, in muscle.
Fibrin.
Gluten.
Legumin,

2, Fats, as— -
Suet.
Lard.
Marrow.
Butter,
Oils.
23

3. CARBO-HYDRATES, as—

Cane Sugar.
Grape Sugar.
Milk Sugar.
Starch.
Arrow-root.
Rice.
Potatoes.

What is the Type of Human Food?

Another complete food is the Egg.

What is the Composition of Mitk ?

cow. WOMAN.
Proteids (casein and albumen), 4°1 3°35
Fats (butter), - - - - 39 3°34
Milk sugar, - - - - 52
Salts, - - - - - 08 \ eat
Water, - - - - - 86 89°54
100 100

It will be observed the woman’s milk is more watery, and
that cow’s milk contains 14 per cent. of solids, while woman’s
milk only contains 10 to 11 per cent. The specific gravity of
milk varies from 1026 to 1030. Asses’ milk most closely
resembles human milk.

Could an Adult live on Milk Alone?

Yes, pretty nearly ; but he would require 8 to 10 pints in
twenty-four hours, but this would give him an excess of water
and fatty matters, which is disadvantageous to the adult, though
it is specially suitable for young persons.
24,
Give a Short Account of Milk Analysis ?

1. Take a 100 parts by weight of the sample, and evaporate
it as rapidly as possible to dryness in a water bath: weigh the
result, and note it as

“ Tota Soups.”
After this ignite it till the ash is quite white, and note this as

“ MineraL Matters.”

2. Evaporate a like quantity to a pasty consistence, add a
few drops of strong alcohol, and let it stand for a couple of
hours; after this digest it with ether at a gentle heat, then
pour off the ether through a weighed filter. Repeat this until
a drop or two of the ether leaves no perceptible residue on
being evaporated to dryness. Dry the residue at 100° C. and
weigh it, and note the result as

“Soxtips not Fat,”

3. Take its specific gravity by bottle, with the usual
precautions as to temperature: average, 1030 to 1032, and
cream reduces the specific gravity, and vice versa.

4, The amount of cream may be roughly estimated by
placing 1000 grains of the milk in a long narrow graduated
burette ; allow it to stand for twelve hours and then read off
the amount of cream thrown up.

Nors—normal milk should contain (about)—

1. Total solids, 12-5.

2. Solids not fat, not less than 9:0: less than this
shows probable adulteration by water.

. Fat, 2°5 to 3:5,

. Ash, ‘7 to ‘8.

. Specific gravity at 60° F. 1030 to 1034,

. Cream, roughly, 10 to 14 per cent.

Oo oO FR Cw
Per cent—

Water, - - - “ 2 89
Solids, ‘ - - - : - 11
100

(1) Proteids,  - - : 3°5

(2) Fats, - - - - 2°5

(3) Sugar, - - - - 48

(4) Salts, - - - - 2

11-0

The “reaction” should be neutral or slightly alkaline—due
to alkaline potassium phosphate.
Milk itself is simply an emuxsion of oil globules.

What Salts are Present in Milk ?

Salts of the alkalies and earths, just like those of the blood,
potassium salts being present in greatest abundance—phosphate
of potassium, chloride of potassium, much phosphate of calcium,
and traces of phosphate of iron.

What ts the General Composition of Pork and Bacon?

Pors—
Proteids,  - - - - - 9°8
Fat, - - - : - 489
Salts, - - - - - 23
Water, - - : - - 39:0

100

Dried bacon resembles it, but of course contains less water
and more fat—fat in bacon, 73°3 per cent.

Pork is indigestible from the fat it contains.

Bacon is more easily digested, because the fat it contains
is easy of digestion ; but this large amount of fat, means a large
excess of carbon in the food.
26

How is this Disadvantage Overcome ?

By cooking it with beans or meat: beans are very rich in
nitrogen,

What ts the Composition of Cheese ?

Proteids, - - - - - 33°5
Fats, : - - - - 24°3
Salts, - - - - - 54
Water, - - - - - 36'8

The cheese contains much nitrogen in small bulk, so that
half a pound of good cheese is equal to one pound of beef. In
“ripe” cheese there is less casein and more fat.

What is the Composition of Eggs ?

An egg weighs about 2 ounces, and consists of—

10 parts of shell.
60 parts of “ white.”
30 parts of yolk.

A single egg contains as much nutriment as 2 ounces of beef,
and four eggs therefore are equivalent to half a pound of beef.
The yolk contains much lecithin—a peculiar phosphorised and
nitrogenised fat, found specially in nerve tissue—and is there-
fore useful for brain work. Eggs contain all that is necessary
for the development of the young animal—except oxygen, which
is absorbed from the air. The “white” consists of albumen
and water; the albumen is very soluble, and enclosed in thin
walled cells: the yolk forms a yellowish emulsion. Lightly
boiled eggs are more easily attacked by the gastric juice, than
either raw or when hard boiled. °

How is the “ Freshness” of Eggs to be Tested ?
By their specific gravity and transparency. Good eggs
27

should sink in a 10 per cent. solution of common salt ; when
one looks through a good egg it is translucent, especially towards
its centre.

How could you tell the Age of a Fowl before the ais
of the Carving Knife ?

Young fowls have large feet and big joints; the old bird
has a thin long neck and violet thighs.’ The flesh of poultry
contains more proteids than lean beef, but less salts.

Sketch an Ordinary Diet.

Meat, = - - - - 8 to 16 ounces.
Bread, - - - - - 12 to 18
Potatoes, - - 2 : - 6

Milk, s - : - - 38

Butter, - - - - - di

Sugar, - - - - - 12

Salt, - - - - - 25

Tea, - - - - - 25

Coffee, - - . - - 33

How are the Tissues affected when Food ts withheld ?

The result is starvation: the body loses two-fifths of the
entire weight, and will then probably die.

The tissues waste thus—

Adipose tissue, - - - - 97 parts lost.
Spleen, - - - - - 63:1
Liver, - - - - - 56°6
Muscle, - - - - - 30°2
Blood, - - 17°6
Brain and Spinal Cia, aia Hart, 0

Probably the chief cause of death is loss of heat.
28

A woman requires one-tenth less food than the male.

Up to nine years of age the food should be chiefly milk and
farinaceous food.

At ten years of age, the child requires half as much as a
woman : at fourteen years of age as much as a woman.

Young growing lads require more food than a full grown
man.

What are the Characteristics of Good Meat ?

The cut section should present a marbled appearance, from
the mixture of fat and muscle. The colour should not be too
pale or too dark. If pale and moist, it shows that the animal
was young or diseased; if dark and livid, it shows that the
animal was not slaughtered, but died with the blood in it.
The muscles of pork, veal, and lamb are always pale. The
muscle and fat should be firm to the touch, not wet or sodden ;
the fat should be free from hemorrhagic points, and the suet
fat should be hard and white. Any juice exuding from the
meat should be small in amount, reddish in tint, and acid in
reaction. The juice of bad meat is alkaline or neutral. The
fasciculi should not be large and coarse, and should be free
from any mucilaginous or purulent looking fluid in the tissue
between.

The odour should be slight and not disagreeable; if the
odour,is bad, it indicates putrefaction or disease: and this can
best be detected by chopping a piece of the meat and drenching
it with warm water, and then smelling the vapour given off;
or thrust along clean knife into it, and smell it after with-
drawal.

If pale and flabby and watery, it shows that the animal was
probably suffering from consumption or the rot. Also examine
the ribs for pleuritic adhesions : the brain and liver for hydatids,
and the lungs for abscesses. Jor parasites use the microscope.
29
What Diseases render Meat Unfit for Human Food ?

1. Pleuro-pneumonia.

2. “Consumption.”

3. Rinderpest or Cattle Plague.

4, Anthrax or Malignant Pustule.

5. Splenic Apoplexy or “ Braxy” in the Sheep.

6. Foot and Mouth Disease in the last stage.

7. Rot or Fluke Disease in the Sheep.

8. Pig Typhoid.

9. Pig Measles.
10. Puerperal Fever or “ Dropping after Calving.”
11, All Acute Fevers.

What well-murked Afections are produced by Diseased Meat ?

1. Trichinosis, by eating pork infested with the trichina
spiralis,

2. Tenia solium, one form of tape-worm, from eating
“measly pork ”—pork infested with the cysticercus cellulosus.

3. Tznina medio-canellata, another form of tape-worm, from
eating measly beef—the most common form in this country.

What Means are used to Prevent Outbreaks of Scurvy ?

The use of lime juice, as well as fresh or preserved meats
and vegetables. Fresh vegetables should always be carried
on ship-board, notably raw potatoes, as they are very effective
and will keep good for a long time. Mollasses and fresh or
preserved meats should also be carried.

What Diseases are Specially said to be Conveyed by Milk?

1. Typhoid Fever.
2. Scarlet Fever.
3, Diphtheria.
And some would say that it may even be the cause of true
tubercular phthisis, but this is more than doubtful.
30
What Points should be inquired into in Examining Bread 2

1. See if there isan undue amount of water; take a weighed
quantity and dry it thoroughly. It should not contain more
than from 42 to 44 per cent. of water.

2. See if there is an undue amount of common salt.
Incinerate a known quantity, digest the ash in distilled water,
acidulate with a few drops of nitric acid, filter and treat with
nitrate of silver; collect, dry, and weigh the precipitate, and
calculate into sodium chloride: every 143°5 parts of this pre-
cipitate (7.e., Ag Cl) is = 58°5 parts of chloride of sodium.

Ag Cl = 143°5
Na Cl= 58:5
Since—
Ag = 108
Cl = 35:5
143°5
and
Na = 23
585

Therefore 143°5 parts of the precipitate of Ag Cl is equivalent,
as far as chlorine is concerned, to 58°5 parts of common salt.
Bread should not contain more than 1 per cent. of common salt.

3. Examine for the addition of alum. Incinerate a known
quantity, boil the ash in pure hydrochloric acid, filter and add
ammonia to the filtrate in excess, when a white precipitate will
be thrown down, consisting chiefly of phosphate of lime. To
this add a large excess of oxalic acid, this will dissolve the
phosphate of lime, but not the phosphates of aluminium or
iron: if any precipitate therefore remain wash, dry, burn, and
weigh it carefully, dissolve the result in strong hydrochloric
acid, estimate the iron by yellow prussiate of potash, calculate
into iron phosphate, and deduct this from the weight of the
precipitate left after adding the oxalic acid, and the result will
be the weight of alum added.
31

4. Find the total ash, by incinerating a known: quantity
and carefully weighing the residue. The ash should range from
1:5 to 2 per cent. If the ash is more than this and not neutral
but alkaline, it probably shows the addition of potatoes.

5. To detect cupric sulphate, add ferrocyanide of potassium
to the bread, when a brick-red colour will be produced.

BURIAL.

What Points have to be attended to in Land-Burial ?

The cemetery should be at some distance beyond the town:
the body should be buried at least 6 feet from the surface and
only one body in each grave; plants of quick growth and dense
foliage should be planted in the graveyard. The soil should be
dry and well-drained, and of an open porous nature.

What Area is Required for a Town ?

To calculate the area required for a town, take the death-rate
at 30 per 1000, and allow two square yards (or metres) for each
grave—i.e., for the grave and space between it and the next.
Another plan is to allow a quarter to half an acre for every
1000 of the population.

What is the Duty of the Medical Officer of Health ?

To find out the causes of increased death-rate in his district,
in order that steps may be taken to put this to rights.

What are the Various Parts of the Public Health Machinery ?

1. The Local Government Board, the Central Authority,
consisting of—
(1) Lord of the Privy Council.
(2) His Secretaries.
(3) President of Local Board.
(4) His Secretaries and Staff.
32

2. The Local Authority.
(1) Urban—The Town Council.
(2) Rural—The Board of Management of Poor.
These respectively appoint, and ought to pay—
3. The Medical Officer of Health.
4. The Inspector of Nuisances.

WATER-CLOSETS.

What are the Classes of Water-Closets ?
1. Water-closets, with valves—e.g., the Bramah.
2. Water-closets, with traps—e.g., the ‘“ Hopper.”
3. Water-closets, with both valves and traps.

What are the Requirements of a good Water-Closet ?

1. It should be non-odorous.
2. It should work effectually with a minimum supply of

water.
3. It should be simple in construction and not liable to get

out of order.

What are the Parts of a Pan Closet ?

It consists of four parts—
1. The basin.

2. The pan.
3. The receiver, in which the pan works.

4, The D-trap usually.

What are the Objections to this Closet ?

Though it is very often used because it is cheap, it is
cumbrous and a great nuisance, and is condemned by the Local
Government Board: the receiver becomes coated with fecal
33

matters, which remain moist and decompose, and gases form,
and these accumulate there in the comparatively large cavity ;
and when the closet is opened these gases come into the house,
and no amount of ventilation will remedy this. The D-trap
is also one of the worst possible of traps. The dip pipe goes
far down and dips into the water from 4 to 14 inches, and all
sorts of dirt collects on its outside and the large space above
it, and it cannot be cleaned out; and it is full of corners and
angles, which just collect dirt. The dip pipe is often badly
fixed—not far enough, or too far down, and not close to the
vertical side of the D. The dip pipe very soon, too, becomes
corroded both above and below the water line, and gases easily
escape from the sewers into the house. Sewer gas eats through
pipes, especially the part not under water.

Ls the Valve or Bramah Closet Good ?

It is not so bad as the last, as there is no pan, and the
receiver is only just large enough for a small valve to work
in ; paper, etc., is apt to stick in the valve and make it leak.
But with plenty of water, and double ventilation, it is a very
excellent closet—in fact, one of the best. In good houses it is
usually for private use and the use of visitors.

What is the “ Hopper” Closet ?

It consists of a simple basin and a trap; the basin is
pyramidal or hopper-shaped, and the trap a simple;,S bend.
With good traps, plenty of water, and good ventilation, it is a
very fair and useful closet, especially if placed in an out-house.
This or the pan closet, in good houses, is usually set apart for
the servants’ use: it is comparatively cheap.

What is Jennings’ Closet ?
It is also a simple basin and trap made, in one piece, of

earthenware, with a hollow plug which drains the water into
the basin.. The feces drop into a very large volume of water,

Cc
34

and when the handle is raised the whole is discharged with
great velocity into the trap below, and through that into the
soil pipe. The hollow plug is used for the basin overflow, and
this is probably an objection to this closet, and another is that
the basin and trap are in one piece. The water-closet cistern
should be separate from the other cistern for drinking and
cooking purposes; and each water-closet should have a waste
water preventer, with a big outlet pipe, so as to have a sudden
and good flush: a large volume delivered quickly is the best.

What Simple Plan may be adopted to prevent Traps from
Freezing ?

Add common salt to the water in the trap after the closet,
etc., has been used.

If the water-closet is meant to receive slops, or to act as a
urinal, the seat should be hinged so as to be turned aside and
prevent it being wetted: or a minature pot de chambere should
be at hand into which to urinate, and it can then be easily
poured into the basin of the closet. There should be a lead
safe under the water-closet to catch any water and prevent
damage to the ceiling of the room below; the pipe from the
safe should be carried out through an external wall, and have
no communication in any way with the soil or any other pipe.
A separate cistern must be used for the closets; “waste pre-
venters” are sometimes used under the water-closet seat, and
are meant to serve as a separate cistern, but this plan is not
good, because—

1. The water enters the basin with only slight force,

2. It is apt to become worn out.

3. It is not thorough disconnection between the water-closet

and the general water supply. >

Traps should be self-cleansing, and all pipes disconnected
where they enter the house, and flushed at the time they are
fouled ; use a copious flush suddenly, and not in driblets, At
the head of each drain there should be a flush tank to collect
the rain water, etc., and discharge itself automatically.
35
How could you Test the House Drains ?

1. Sex IF THERE ARE DRAINS, AND IF THEY ARE PERVIOUS.
Draw up the water-closet handle for a few minutes, and
watch if there is a flow past the grid of an external trap.

2. Sen ir THE Pires Leak.

Plug up the lower end of the drain with clay, and fill the
pipe with water: watch if it subsides, and how fast. If the
drain be very long, test it in 30 or 40 feet lengths. This is the
HYDRAULIC TEST.

3. Sgn ir THE PIPEs ARE AIR-TIGHT AND IF ALL THE OPENINGS
ARE TRAPPED.
To do so you can either use the peppermint or paraffin test,
or the smoke test. Make fumes of paraffin inside a closed
vessel over the grid at the outside trap, and force the fumes
up the house pipes by means of a small fan; or smoke made
from oily waste, such as engine-cleaners use, can be forced in;
and when the smoke is seen coming out at the ventilating
openings in the roof, then each room is to be visited and
carefully examined for the smell of paraffin, peppermint, or the
presence of smoke. This will show whether the pipes are
air-tight, or whether all the openings are trapped. In using
paraffin or peppermint to test the air-tightness, the fumes
should not be forced in under PressuRE; and probably, there-
fore, it is better to use peppermint and hot water without the
aid of a fan at all. In testing the venTiLation, however, it is
necessary to use slight pressure.

Jf the Drains are not Trapped, what ts the Result ?

If the drains are not trapped they become ventilators to
the house, or air inlets, because of the warm air inside the
house—like chimney shafts—especially when many fires are
going, and in the night and cold weather when doors and
windows are shut. i
36

What are the Advantages of Traps ?

If they are well sealed and self-cleansing, they prevent the
passage of foul air, unless under great pressure. If not well
sealed and self-cleansing, they simply become small cesspools.
Gases, however, may pass through water seals by diffusion.

How Deep should the Water Seal be ?
An inch and a half.

How would you Test Traps ?

By means of the smoke, peppermint, ether, or ammonia test.
Some would use Valerian and then put the cat into the room,
when it will go direct to the leak. |

What are the worst forms of Traps?

The Bell-trap and the D-trap. The Bell-trap is usually used
for sinks, and the D-trap for water-closets. Even when the bell
trap is in its proper position, its effect is doubtful; and as it
allows the water of the sink to pass through so slowly, the
servants usually take it out altogether—as it is quite loose—
and this opens up a direct communication between the sewer
or house drain and the interior of the house. The D-trap
simply accumulates dirt, and is one of the worst possible of
traps. Traps and “fittings” should not be in one piece, and
they cau be more easily examined and more securely jointed.
The trap should be as close as possible to the “ fitting "—e.g., a
water-closet—because, if there is a long pipe between, it simply
becomes a dirt collector and very offensive.

Give the Characteristics of a good Trap ?

1. It should be free from angles and corners and places
where filth could collect, and generate noxious gases.
2. It should have a tree way for discharges to pass through,
37
without breaking their form. A round pipe is best with a water
seal of 14 or 2 inches,

3. The body for fixing in horizontal pipes or drains should
be smaller than the inlet, so as to hold the smallest necessary
amount of water and be easily changed.

4, The minimum size should be used consistent with
security.

5. The water-way into the trap should be larger than the
body part, in order to secure a good flush.

6. The water must fall on the standing water in the trap,
and not on the side of the trap.

7. The inlet side of all traps fixed upon drains outside the
house should be open to the atmosphere, to let out bad air from
decomposing matters in the trap.

8. In cold countries the mouth of the trap should be sealed
over, or the ventilation taken at some distance from the trap ;
or keep it well down into the earth.

9. It must be self-cleansing, air-tight, and ventilated on
both sides.

If the Trap is made of Lead, what Weight should be Used?

Use 7 to 8 lbs. lead to the superficial foot, never less than
6 lbs. lead; and if much hot water is to pass through, do not
use less than 8 lbs. lead.

How are Traps to be Cleaned ?

By means of a cap and screw below the water dip and on
the house side of the trap; this is not necessary in water-closet
traps, because the hand can get down the basin to the bottom
of the trap, but it is necessary in sink and lavatory traps.

What are the Objections to the “ Bell” Trap?

The water is obstructed in its free passage, and the trap is a
receptacle for dirt: no body of water can pass quickly through,
38

‘because there is no room; and the servants therefore lift up
the cover, and put the house in direct communication with
the sewer. The water dip, also, is too small, being only three-
eighths of an inch, and the slightest back draught or puff enters
the house. It also very quickly evaporates, unless the water is
frequently changed.

What are the Objections to Antill’s Trap ?

When the grating is off this does not destroy the trap
certainly, but the water dip is too small and the trap is not
self-cleansing ; dirt and grease lodge in the corners, and there
is no free passage for the water to pass quickly.

Is the Gulley form of Intercepting Trap a good form ?

No; much water lodges in it, and filth as well, which
decomposes, producing foul gas that passes up the waste pipe
into the house; the water-trap, also, is not changed every time
the trap is used. It does very well for yards and courts, and
to catch the road detritus.

What is the Action of a Discharge of Water into a Drain?

Its action is double—driving and sucking: it drives before
it and sucks after it, and unseals traps from momentum and
syphonage unless they are ventilated. It will also force traps
at lower levels as it shoots past the opening of the drain,

What Size of Ventilating Pipe should be Used ?

From 3 to 4 inches is large enough even for from four
to six closets, one above the other.

How much Water should be allowed to Flush a Water-Closet 2

Three gallons is probably the best; it should be delivered
suddenly, so as to get rid of everything by one flush.
39

What are the Advantages of having a Ventilation Pipe in the
Valve Box of Water-Closets ?

1. It prevents the overflow from the basin being unsyphoned.

2. It allows the overflow to pass freely through the closet
traps. 3

3. It allows gases to escape that come from the trap if it is
not properly emptied.

When the Bramah closet is thus fitted, it is probably the
best.

What are the Stages of Sewer Gas Poisoning ?

1. The odorous or warning stage.
2. The narcotic or dangerous stage.
3. The actual disease stage.

4, Death.

What does “ Infectious” mean ?

A disease communicable from one person to another whether
by actual contact, or through the agency of such media as the
air, water, clothes, etc.; they are mostly “zymotic,” that is,
due to a special “ferment” or micro-organism, the growth of
which is believed to give rise to the symptoms. The micro-
organism is the “ specific contagium.”

What is “ Contagious” ?

A disease that can only be communicated through direct
contact is called contagious—e.g., syphilis,

Give Examples,

Small-pox and scarlet fever are very infectious.
Typhoid fever and erysipelas are limited very easily, provided
the sanitary conditions are good.
40

Can all be Propagated through the Atr ?

No. The poison of—
Small-pox
Typhus
Scarlet Fever
Measles

But the poison of—

Treo is non-volatile.

is volatile.

The volatile only should, properly speaking, be propagated.
through the air, though the specific contagion of typhoid fever
may be thus carried by means of fine dust, from dried stools, etc.

DISINFECTANTS.
What is a “ Disinfectant” ?

A substance that can prevent infectious diseases from
spreading, by destroying their specific poison, so that it loses
its power to infect—e.g., permanganate of potash.

What is a : Deoderiser” ?

A substance that removes or absorbs foul-smelling gases, or
disguises their smell by producing another and stronger smell—
e.g., Vinegar, and Eau de Cologne.

What are “ Antiseptics” ?

They very closely resemble disinfectants, but the term is
usually applied to substances preventing the origin of the
disease, whereas the “disinfectant” is used rather after the
disease has actually begun. Antiseptics check ‘or prevent
fermentation and destroy specific micro-organisms; they may
either act on organisms of definite form, as the various forms of
bacteria, or on unorganised ferments: in the one case, they
arrest the development and reproduction; in the other, they
check the catalytic action of the ferment.
4]

What way do the Antiseptics Act?

1, They may oxrpisz the ferment directly—as, for example,
permangamate of potash (Condy’s fluid); or indirectly, as

chlorine and water.

2. They may kill by the cuemicaL arrinity between the
antiseptic and the ferment—e.g., carbolic acid has an affinity

for albumen, and thus kills the micro-organisms, which are

protoplasmic bodies.

3. They may have a direct Toxic action on the micro-
organisms—as mercuric iodide, mercuric chloride, quinine, and

salycilates.

Give a List of the more Common Disinfectants ?

. Heat and Cold.

. Charcoal, especially animal.
. Chlorine.

. Nitrous Acid.

Iodine.
Bromine.

. Sulphurous Acid.

. Carbolic Acid.

. Terebene.

. Cupralum.

. Sanitas.

. Condy’s Fluid.

. Chloralum.

. Chloride of Lime.

. M‘Dougall’s Powder.
. Sulphate of Copper.
. Chloride of Zinc. .

. Green Copperas.

. day’s Disinfectant.

. Cooper's Salts.

. Bichromate of Potash or Chromic Acid.
42

How is Heat Applied ?

Dry heat is applied by means of a hot air chamber; it is
very effective, provided the article be freely exposed to it, and
for a long enough time at a high enough temperature.

What Temperature should be Used ?

Most articles of dress can stand a temperature of about
255° F. without scorching, but it is probably better not to go
above 230° F. lest they might be charred.

Is Chlorine a good Disinfectant ?

Yes, in the presence of water it is very powerful; but it
is not good for the sick-room, as it is too irritating for the
respiratory passages. .

How can tt be Produced ?

1. In Smaty Quantity.
2. In Lance Quantity.

It may be evolved slowly from—
(1) Chloride of lime (what is evolved is probably rather
hypochlorous acid and not pure chlorine).
(2) From Condy’s fluid and hydrochloric acid.
(3) From chlorate of potash and hydrochloric acid.

In large quantities from—
(1) Common Salt, manganese dioxide, and sulphuric
acid.
(2) From manganese dioxide and hydrochloric acid.
(3) Bleaching powder with some dilute sulphuric acid,

How is Nitrous Acid Produced ?

By means of strong nitric acid and copper filings.
43
Is it often Used ?

Not very; it is very good for removing the smell of the
dead-house, but cannot be used in living rooms, as the fumes
are very irritating and dangerous to the respiratory passages.

What ts Cupralum ?

It consists of terebene, copper sulphate, and potassium
bichromate.

What is this Used for ?

It is very good to disinfect bowel discharges, water-closets,
urinals, and drains.

What ts Chloralum ?

The chloride of aluminum.

What are its Advantages ? \

It is non-poisonous, non-volatile, inodorous, and very cheap ;
it removes foetor from effluvia even better than chloride of lime,
and arrests putrefaction.

What is M‘Dougall’s Powder ?

It is carbonate of lime and sulphite of magnesia, and is
therefore a means of conveying sulphurous acid.

What ts Green Copperas ?
It is ferrous sulphate.

What is its Use ?

It is useful to disinfect heaps of manure and sewage, and
cholera evacuations.
44
What is Cooper’s Salts ?

It is composed of common salt, calcium, and magnesium
chlorides. It is used for the sewers and streets: it is useful to
keep the streets moist and keep down the dust.

What Precautions, as regards Disinfection, should be Taken ?
1. In ANTICIPATION OF THE POSSIBLE APPROACH OF CHOLERA.

(1) All Local Authorities should at once provide themselves
with a supply of carbolic acid,* chloride of lime, and ordinary
quicklime,

(2) All open drains should be daily cleansed by sweeping,
and thereafter dusted with ordinary quicklime.

_ (8) Where pipe-drainage has been introduced into houses,
and, from the escape of offensive gases, is found to be defective,
—notice should at once be sent to the landlord and to the
sanitary inspector, and after a thorough flushing with water,
a solution of carbolic acid, made by adding two wine-glassfuls
of ordinary carbolic acid to a gallon of water, should be passed
down the drain daily, or oftener if necessary.

(4) After any dung-heap or other accumulation has been
removed, the site of the accumulation should be covered with
ordinary quicklime,

(5) Water to be used for drinking, cooking, and other
domestic purposes, which is suspected to be tainted, should in
all cases be boiled.

2. WHERE CHOLERA IS ACTUALLY PRESENT.

(1) To disinfect the vomited matters and discharges of the
patient. This may be readily effected by receiving them into
vessels containing two pints of the solution of carbolic acid
already mentioned.

 

* Use the crude carbolic acid for this purpose as it is cheap, and is
equally as effective as the purer varieties: use one pint of this to two
gallons of water.
45

(2) If possible, the discharges, etc., thus disinfected, should
be buried in the earth at a depth of at least two feet; or, if
passed into a drain, the drain should immediately afterwards
be flushed with water.

3. IN THE EVENT oF RECOVERY OR DeatH.

(1) The bedding and clothing should at once be destroyed
by burning.

(2) From two to four table-spoonfuls of ordinary flowers of
sulphur (according to the size of the apartment) should be
placed on an iron shovel along with some live coal or peat.
While the sulphur is burning, the door and windows of the
apartment should be kept shut, and should be opened only at
the expiry of an hour. The shovel should be supported over
a tub containing water.

(8) The bedstead, the floor, and the woodwork of the
apartment should be washed with the carbolic acid solution
already mentioned, and afterwards with ordinary soap.

(4) The ceilings and the walls should be thoroughly scraped
and washed, and afterwards coated with lime-wash containing
four tea-cupfuls of chloride of lime to the pail of lime-wash.

(5) Articles of clothing which have not been in immediate
contact with the sick, or which have been removed at the
commencement of the illness, should be disinfected by being
sprinkled with, and if necessary, steeped for a night in the
carbolic acid solution already mentioned.

(6) Should death occur, the body of the deceased should
be wrapped in a sheet which has been steeped in, and thoroughly
saturated with, the carbolic acid solution, and thereafter buried
without delay.

In the case of Infectious Fevers in a Dwelling-House, what
Precautions should be Taken ?

1. Complete isolation of the patient from all the other

members of the family at once, and as long as he is sick;

and keep up this isolation till all danger is past—eg., until
46

desquamation is complete in the case of scarlet fever—usually
in eight to ten weeks, but may be longer.

2. Choose a well-lighted room, and, if possible, higher up
than other rooms of the house, as in many cases the poison is
volatile, and therefore tends to rise to the highest point. The
room must be well ventilated by windows and fires,

3. Remove all useless furniture, such as carpets, curtains,
unnecessary chairs and tables, etc.

4. Secure the services of an obedient and trustworthy
attendant who will carefully carry out all orders of the medical
attendant as regards the disinfection of excreta, soiled linen, etc.

5. A sheet moistened and kept moist with a strong solution
of chloralum, sanitas, cupralum, Condy or carbolic acid, should
be suspended outside, over the door of the sick-room, so as to
complete the isolation.

6. The nurse must be isolated too, and must change her
clothes before leaving the house; the doctor must be careful
to wash his hands before he leaves the sick-room ; all dishes,
spoons, etc., and all articles of food once in the sick-room,
should be carefully isolated and avoided by the rest of the
family, and also by cats and dogs.

7. Infected clothing, soiled linen, etc., must be removed at
once, and immersed in a tub, containing some of the disinfectants
already mentioned, before they leave the room; the tub should
stand in the sick-room: saucers and flat plates filled with the
disinfectant may be also scattered about the room.

8. All the excretions, as feeces and urine, should be instantly
covered with the disinfectant, and received into vessels con-
taining it—the feces must be disinfected before they are
emptied down the water-closet: this is specially necessary in
typhoid fever. In scarlet fever and diphtheria, the expectora-
tion should be caught in little pieces of cloth, which must at
once be burned.

Nore that carbolic acid or turpentine must not be mixed

with solution of permanganate of potash.
47

9. In many cases it is better to remove the patient from the
place where he caught the disease, especially in the case of
typhoid fever. In convalescence from scarlet fever attention
must be paid to warm baths and frequent inunction with
some antiseptic ointment, so as to disinfect the scales. In
convalescence from any infectious fever, the patient must not
be allowed to read Books, as they are so difficult to disinfect
properly, and certainly never books from public libraries—his
reading should be confined to the newspapers and periodicals,
or such books as can be readily burned after being read.

How would you Disinfect Empty Rooms or Uninhabited Places ?

After the patient has recovered (or died) and left the sick-
room, it must be carefully fumigated with sulphurous acid ;
this acid is very useful for this purpose, because it is so easily
produced, is so cheap, and is very effectual. Clothing and
bedding should be removed to be disinfected by other means ;
the furniture should all be carefully and thoroughly washed
with a strong solution of chloralum and carbolic or terebene
soap, and removed from the room, Any article that would
spoil—e.g., a picture—must be removed from the room, and
articles that will not spoil should be turned up or hung on lines
stretched across the room, so as to expose them freely to the
action of the sulphurous acid. After this the doors, windows,
and chimney must be carefully closed up, all cracks and seams
admitting air also carefully plugged, the object being to keep in
all the sulphurous acid about to be produced, and also prevent
its admixture with the fresh outside air entering through cracks,
doors, etc. Then the sulphur should be set burning, and the
room carefully sealed up for at least an hour. At the expira-
tion of this time the doors and windows are to be widely opened,
the stuffing removed from the chimney and the cracks and seams
of the doors and windows, so as to allow the fresh air to blow
freely through it: it should be left thus for six hours or so, and
then the papering of the wall is to be removed and the walls
scraped, the ceiling to be washed with quick-lime and whitened,.
48

and the walls to be repapered and replastered if necessary ;
and lastly, the floors and wood-work scrubbed with chloralum,
or some other disinfectant, and washed with carbolic, sanitas, or
terebene soap.

How much Sulphur is Required ?

About 1 1b. for every 1000 cubic feet of space: this will
produce 11 cubic feet of sulphurous acid gas.

How and under what Precautions should it be Produced?

In an iron shovel, or some such vessel that will not crack,
supported on a pair of tongs, or bricks, over a bucket or tub
of hot water; this is because, should the sulphur run over the
edge of the vessel, it will fall into the water and not set fire
to the floor: the hot water is to produce steam vapour, as the
sulphurous acid vapour without watery vapour is inert. The
sulphur is made to burn by placing some live coal or peat in
the shovel.

Can Sulphurous Acid Gas be Produced in any other way ?

Yes; by means of lamps burning bisulphide of carbon.

How much ts Required ?

Sixteen ounces for every 1000 cubic feet.

What are its supposed Advantages ?

It does less harm to articles left in the room, and the room
does not require to be shut up so long afterwards,

How would you Disinfect Clothing and Bedding ?

In many cases clothing and bedding should be at once
burned, but if this is not done, they are best disinfected by
dry heat in a hot air chamber; hair mattresses will be better
49

to be teased out and fumigated or exposed to hot air and
afterwards to fresh air. In some cases clothing may be dis-
infected by being steeped in some antiseptic, as chloralum or
carbolic acid, and boiled: if a solution of permanganate of
potash be used, the articles should be merely immersed in the
fluid and afterwards rinsed out in cold water, otherwise they
will be stained. Rags and articles of little or no value should
be at once burned.

How are Water- Closets and Urinals to be Disinfected ?

By chloride of lime, chloralum, cupralum, or copperas ; for
cesspools and middens and manure heaps, use copperas, 3 lbs.
to the gallon of water; or cupralum or chloralum, each 1 Ib. to
the gallon.

What ts to be done in Fatal Cases ?

In cases of small-pox, scarlatina maligna, the body should
be washed with a strong solution of carbolic acid or chloralum,
or be at once enveloped in a sheet saturated with the same
antiseptics, placed in a.coffin as soon as possible, and plenty
of the antiseptic poured in, screwed down and buried as
soon as possible, or else be sent to the mortuary. The
linen worn by the patient at death should be buried or
burned at once.

Give a List of “ Trade Nuisances” ?

1. Keeping of animals, except under certain conditions,

2. Slaughtering of animals.

3. Industries in which animal substances are chiefly dealt
with—as gut-scraping, manure manufacture, melting of fat, and
soap-boiling.

4. Industries in which vegetable or mineral matters are
chiefly dealt with.

5. Trades which deal in mixed matters.
50

WARMING.

What is the Principle of Warming by Steam ?

The cold air surrounding the steam pipes rapidly condenses
the steam, which, in being condensed, gives out its latent heat.

What do you mean by the Latent Heat of Steam ?

The amount of heat which disappears in converting water
at 212° F. into steam of the same temperature.

How much ds this ?
536 thermal units.

What Becomes of this Heat ?

Jt is given out when the steam is condensed, and it is this
that heats the room.

What is the Surface Temperature of a Pipe filled with Steam
at 212° F.?

About 200° F.

What Size of Pipe would you Allow ?

A pipe four inches in diameter.

How much Pipe ts Required.
Allow—
1 square foot for every 6 square feet of glass.
1 square foot for every 120 square feet of walls ang roof.
1 square foot for every 6 cubic feet of air. ;
51
Is Air or Water more easily Heated ?

Air: the amount of heat sufficient to raise 1 cubic foot of
water one degree will raise 2850 cubic feet of air one degree.

How is the Condensed Water got Rid of ?

There must either be a siphon used for taking it off, or else
a float ball valve steam trap used.

If the Water were not Removed, what might happen?

The water would cause the steam to be condensed so rapidly
that a vacuum would be formed in the boiler, and hence the
boiler, unless it be specially strong, may be crushed in by
atmospheric pressure.

What has to be attended to in Jointing the Pipes?

Must allow room for expansion: cast-iron expands one-
eighth of an inch for every 10 feet. Lzap must not be used
in jointing as it becomes permanently expanded ; use iron or
tin instead : if lead be used, the joints soon become loose. The
pipes should not be connected with any part of the building ;
the horizontal ones should be laid on rollers to allow of free
movement during expansion and contraction.

Is Steam much used for Heating ?

No; it has long been superseded by lot water apparatus of
various kinds.

What are the Varieties of Hot Water Apparatus?

1. The Low Pressure,
2. The High Pressure.

Tue Low Pressurs.—In this the water is at or below the
boiling point: the pipes do not rise far above the boiler, and
52

therefore the boiler and pipes need not be vERY strong: one
pipe rises from the top of the boiler, traverses the places to be
warmed, and returns to terminate near the bottom of the boiler.
The boiler may be open or closed.

Tue Hicw Pressure.—tIn this the water is heated to 350° F.
and upwards, and is therefore constantly seeking to burst out
as steam, with a pressure of 70 lbs. or more to the square inch,
and therefore we must have a very strong or high pressure
apparatus. The pipe is of iron, about 1 inch in diameter, and
made very thick: the boiler should be very strong as every.
344 feet in height of pipe means 15 Ibs. to every square inch
of the interior of the boiler. The small strong pipes may be
made to open into larger pipes in rooms or corridors, etc.
Four-inch pipes are used for greenhouses, conservatories, and
hothouses ; and pipes of 2 or 3 inches for churches, factories,
and dwelling-houses.

How much Air should be Allowed for in Heating ?

Allow 4 cubic feet of air to be warmed per minute for each
person, and 1} cubic feet for each square foot of glass.

How much Air will a Cubic Foot of Water warm ?

A pound of water in losing one degree will raise 4 Ibs. of
air one degree ; but water is 770 times heavier than air, and a
cubic foot of water in losing one degree will raise 770 + 4 = 3080
cubic feet of air one degree. A square foot of radiating surface
of steam pipe is enough to heat 200 cubic feet of space,

Is it better to warm by Hot Water or Steam ?

By hot water, as it takes five and a half times as long to
drive water off as steam as it does to raise it from the freezing
to the boiling point.
53

How does an Open Fire warm the Air?

The fire warms the walls and furniture, and these in turn:
warm the air, so that the walls are warmer than the air.

Compure Brick and Iron Stoves.

Brick stoves and flues are worse conductors of heat than iron
ones, but the brick surface parts with heat more quickly than
an iron one. The slow conduction and greater thickness makes
changes in the fire less felt and keeps hotter longer after the
fire is out, and it does not spoil the air so much as an iron one.
Iron stoves heat rapidly, and the effect is therefore unequal
both on persons and on the air. They cool rapidly also, and
carbonic oxide is formed if they are allowed to become too hot.
It is better to line the iron stove with fire-brick, as it equalises
the effect on it better.

Whether is Cast or Wrought Iron worse ?

The bad effects are three times as great in CAST IRON.

What are the Special Merits of Galton’s Grate ?

1. It ventilates the room.

2. It maintains an equable temperature at all parts of the
room, and prevents draughts.

3. It throws more radiant heat into the room than other
grates.

4, The fire-bricks keep the fire from going out, and prevents
rapid changes of temperature in the room.

5. It economises fuel, it uses the spare heat, and insures
complete combustion.

6. It prevents smoky chimneys.

How ‘loes the Electric Light affect the Air of a Roum?

It sets free nitric or nitrous acid, and should be kept
separate from the air of a room.
54

HOSPITALS.
What is the best Site for an Hospital ?

It should be in an airy open space, or at the outskirts of the
city, and on a raised, dry, pure, porous soil.

What is the best Form of Hostal ?

The Pavilion style—ie., a collection of small hospitals,
connected by corridors—e.g., the Royal Edinburgh Infirmary.
The distance between the pavilions should be about twice the
height of the pavilions. This allows of a free circulation of air
round each pavilion,

How many Patients should be in each Ward ?

From twenty-four to thirty-two on an average: there should
be fewer in a Surgical ward than in the Medical. The number
in a Medical ward will depend more on the convenience
of nursing than on anything else, but this is not the case in
a Surgical ward.

How much Cubic Space would you allow in an Hospital ?

For an ordinary hospital, the usual figure is 1200 cubic feet ;
for infectious cases it should be from 2000 to 3000 cubic feet
for each patient. In the ordinary medical wards in Edinburgh
the space is 2220 cubic feet per head.

What should the Superficial Area be ?

90 to 110 square feet for each patient. This space is
necessitated for facilities of nursing and the conveniences of
ward administration. The height of the ward should be about
14 feet, and its breadth 25 to 30 feet.
55
How should the Windows be Arranged ?

A window between each bed, and the space between each
window should be about 6 feet 8 inches wider than the bed;
they should be 24 feet from the ground and about 1 foot from
the ceiling, and there should be a part at the top to open by
sloping inward: the glass should be plate to economise heat.
The windows at each side of the ward admit of cross ventilation
by perfilation, though it is apt to be rather draughty.

How should it be Heated and Ventilated ?

For fresh air inlets there should be a Sherringham valve
near the ceiling between each window, or else a Tobin’s tube.
For heating, use Galton’s grate and hot water pipes. The gas
jets should have a bottomless lantern and extraction flue over
each. The beds should be of iron and there should be as
little furniture as possible.

How should the Water-Closets, etc., be Placed ?

At the end in a little projecting tower, and shut off from the
ward by moving doors and lobby with cross ventilation. Allow
one closet for ten beds, or three for thirty-two.

What is the best Form of Floor for an Hospital ?

Hardwood, polished and varnished, laid on concrete for the
ground floor.

What is a Cottage Hospital ?

It is a hospital for the sick poor of rural districts, but
infectious and incurable cases are excluded.

How many Beds should it contain ?

Six beds for a population of 6000; it should not contain
more than twenty beds.
56
How are the Wards Divided ?
Three beds in male ward.

Two beds in female ward.
And one ward used for operating room.

How Large should the Hospital for Infectious Diseases be ?
One bed for every 1000 or 2000 persons in the town.

What Space should be allowed Jor Infectious Diseases ?

The floor space should be from 144 to 170 square feet: the
height as before, 14 feet; and the total cubic space, therefore,
from 2000 to 3000 cubic feet. Small-pox cases require most
space, and the wards should be well apart or completely cut off
from the other wards. Avoid curtains, carpets, etc.

What Space should be allowed in Schools ?

From 180 to 250 cubic feet fur each scholar: dormitories
should have at Least 240 for each occupant.

What Space is allowed in Convict Prisons ?

It depends whether the convicts occupy the cells during the
night only or both night and day. If only during the day the
space may be less, say about 250 to 300 cubic feet ; in the other
case, allow about 600 cubic feet.

 

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