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English Pages [56] Year 1966
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i
The "Reason
Why
9
Books
TREE PRODUCTS Irving
and Ruth Adler
The John Day Company
New
York
The "Reason Why" Books by Irving and Ruth Adler AIR
ATOMS AND MOLECULES COAL EVOLUTION FIBERS
HEAT HOUSES INSECTS AND PLANTS IRRIGATION: CHANGING DESERTS TO GARDENS
LEARNING ABOUT STEEL (former title: The Story of a MACHINES MAGNETS NUMBERS OLD AND NEW NUMERALS: NEW DRESSES FOR OLD NUMBERS OCEANS
Nail)
RIVERS SETS
SHADOWS STORMS
TOUCH AND SMELL THE EARTH'S CRUST THINGS THAT SPIN TREE PRODUCTS WHY? A BOOK OF REASONS WHY AND HOW? A SECOND BOOK OF REASONS YOUR EARS YOUR EYES TASTE,
Copyright All rights reserved.
or by
any means
No
©
1966 by Irving and Ruth Adler may be reprinted, or reproduced in any form mechanical or other (including but not limited to photo-
part of this book
electronic,
copying, recording, or a process of information storage and retrieval), without permission writing from the Publisher, The John Day Company, Inc., 62 West 45th
m
10036 Published n the same da ° y '
Hmit,,! Library of Congress Catalogue Card Number: Printed in the United States of America
AC
Street
in
Canada b y Longmans Canada
66-10575
Contents
A
Great Treasure
What
Is
4
a Tree?
6
Inside the Living Tree
8
The Use of Trees in Ancient Times The Use of Trees: From Ancient Times From Forest Tree into Log From Log into Lumber
11 to
1500
15 17 18
Other Uses for Logs
20
Wood Charcoal from Wood
22
24
Plywood
25
Facts about
Other Man-made Building Materials from
Wood
28
The Early History of Paper The Story of Wood Pulp
31
Paper from Chemical Pulp
35
Naval Stores
38
We Use Barks We Use Fruits We Use
40
Sap
U.
S.1386132
32
42
44
Lignin
45
Trees for the Future
46
Word
47
List
A
Great Treasure
Trees are one of our greatest treasures.
We plant trees near our homes because their leaf -covered
Their leaves
branches give us shade.
make
soft
sounds as gentle
winds blow through them. to hear these sounds.
nests in the branches It is
We
It is
pleasant
Birds build their
and hollows
of trees.
pleasant to hear the songs of birds. plant trees near our
homes because
trees are beautiful to look at.
Farmers plant blocks of
trees near their
farmhouses and barns as a protection against strong winds.
Windbreaks help
keep barns and houses warm. Farmers plant belts of trees around their Shelterbelts
fields.
keep strong winds from blow-
u
>
away the good topsoil in which farmers grow their crops. Trees that grow close together over great stretches of land make up forests. Forests are the homes of wild animals and birds. The roots of forest trees prevent ing
and keep
floods
away by heavy
soil
from being carried
rains.
Trees are a great treasure, too, because
many products we get from them or make from them. We get products such of the
as fruits, nuts
the trees are trees to
still
make
This book
from
trees
from
trees.
and saps from
is
standing.
trees while
We
cut
down
other products from them.
about the products
we
get
and the products we make
What
A
tree
is
Is a
Tree?
a living thing that belongs to the family of
plants. Its roots hold
it
firmly in the ground. It has a
The trunk is made up of many layers, one inside the other. The innermost layer of the trunk is called the pith. The outermost layer is called the bark. There are layers of wood trunk shaped like a cylinder (SILL-in-dur).
in
A
between the pith and the bark.
The crown
of a tree
is
usually
and branches. The crown
palm tell
trees,
is
made up
of
tree has a crown.
made up
some
trees,
only of leaves.
one kind of tree from another
of leaves, twigs
is
such as certain
One way we can
by the shape
of
its
crown.
There are two main families of
trees.
family of conifers (KON-uh-furs).
One
family
is
the
The other family
Needles and cone of a pine, which
is
a conifer
is
the family of broad-leaved trees.
Trees in the conifer family usually have long, thin,
needle-shaped leaves. Most conifers keep their leaves
all
year round. These conifers are called evergreens. Pine,
hemlock and spruce are examples
Some evergreen
of evergreen conifers.
conifers are used as Christmas trees.
Conifers produce seeds that have no protective covering.
The
seeds are on the scales of a cone. Conifers are
also called softwoods.
Broad-leaved trees usually lose their leaves each year
and grow new leaves the next
year. Trees that lose their
leaves each year are called deciduous (dih-SIJ-yuh-wus) trees.
Maple, oak and birch are examples of deciduous
broad-leaved
trees.
The seeds
of broad-leaved trees
have
a protective covering. Broad-leaved trees are also called
hardwoods.
Leaf and
fruit of
an oak, which
is
a deciduous hardwood
Inside the Living Tree
A
like
tree,
all
living things,
(SELLS). There are many
Each kind
of cell has
the tree alive and
its
make
made up
of cells
different kinds of tree cells.
own it
is
special job to
do
to
keep
grow. Cells are so small they
can be seen only with the help of a microscope. Cells reproduce selves
by
(
REE-pruh-DYOUS
from the ground. Certain
of the trunk carry water all
or
make
cells like
draw up water and mincells in
the
woody
and minerals from the
parts of the tree. These cells are called
lum)
them-
splitting in two.
Cells in the roots of the tree erals
)
cells.
layers
roots to
xylem (ZY-
Cells in the leaves of the tree use water, air
and energy from sunlight
to
make food
for the tree.
Some root cells have root hairs. The root hairs grow out into the soil. They
draw
in minerals and water from the soil that
them.
surrounds
6*3**sr"
Other
cells in
the trunk, on the innermost side of the
bark, carry water with food in parts of the tree.
em)
cells.
These
it
from the leaves
phloem
cells are called
The water with minerals
or food in
(
to all
FLOW-
it is
known
as sap.
A
tree
grows
in
two ways.
It
grows
in height
and
its
trunk grows in thickness.
When new
cells in
cells,
There
is
the tips of the branches split and form
the tree grows in height. a layer of cells
between the phloem and the
KAM-bee-um When cambium cells split in two and form new cells, some of these cells become new phloem cells and others become new xylem cells. In this way a new layer of cells is added to xylem called the cambium
(
)
.
Bark
Phloem
Cambium Pith
Xylem. This tree has five rings of xylem cells.
Diagram
of the trunk of a tree, cut crosswise
9
the trunk of the tree and the tree grows in thickness. This
growth mer.
If
is
faster in the springtime than
the trunk
is
it is
in the
sum-
cut crosswise, the difference between
summer growth next to it shows up as a ring around the pith. You can find out how old a tree was when it was cut down by counting the number of tree rings. Each ring stands for one year of the spring growth and the
the tree's age.
Some softwood
trees
have a network of tiny canals
running through their bark and wood. These canals are called resin
(REHZ-in)
canals. Special cells along the
make a liquid called oleoresin (OH-lee-ohREHZ-in). The oleoresin collects in the resin canals. Every plant cell has a cell wall around it. The cell wall is made up largely of tiny fibers of cellulose SELL-yuhlohss In woody plants the fibers of cellulose are held resin canals
(
)
.
together by a chemical called lignin
makes the
cell
wall
(
LIG-nin )
.
Lignin
stiff.
Count the tree
10
old
was
was
cut
rings.
this tree
down?
How
when
it
The Use
Man
of Trees in Ancient
Times
has been making things from trees and getting
things from trees for thousands of years. Earliest
man was
a food-gatherer. His food consisted
of the animals
he
berries, fruits
and nuts he
killed, the fish
with wooden spears,
trees.
He
roots,
killed animals
and throwing-sticks.
fires.
He dug up
He
roots with
He gathered nuts and fruits that Earliest man had no permanent home.
wooden digging grew on
collected.
clubs
cooked them over wood
he caught and the
sticks.
He made his home wherever he could find food. About 7,000 years ago man began to raise his own move from place to place in search of it. He settled down in one place. He built permanent shelters. He made tools and furniture. He food.
Then he no longer had
Wooden
to
throwing sticks used by ancient food gatherers 11
.
«.
Wooden implements
made about 4000 years ago
made
clothing and dishes.
of the materials
He built and made
he found nearby. Trees grew
the places
where man made
often used
wood and
and making
things out in
his settlements.
most of So
man
other tree products for building
things.
much people who
Great forests covered years ago. So the
of
Europe thousands
lived in central
of
Europe
made many things from wood. They built wooden houses.* They made wooden tables and benches. They made wooden mallets, ladles and bowls. They made dishes by sewing together pieces about 4,000 years ago built and
of birch bark. °
For more information see Houses by the same authors, The John Day Company, 1964.
12
There were no trees
palm
forests in ancient Egypt. Tall
grew well because
The
of Egypt's dry climate.
Egyptians sometimes used the long, strong leaves of the
palm
trees for
making the framework
of their houses.
They covered this framework with river mud. Because there was almost no rain, these dried mud houses lasted a long time.
The Egyptians
also
wove mats and
baskets
out of palm leaves. Other kinds of trees also grew in
Egypt. But these trees were small and produced
Some
wood was used
wood
for
mak-
ing hoes and plows. Sometimes the Egyptians used
wood Then
of a poor quality.
of poor quality for
they covered the of gold.
cause
of this
making furniture and
wood with
The Egyptians had
wood
of
statues.
plaster, paint or thin layers
to
import good wood. Be-
good quality was
scarce, the Egyptians
This Egyptian statue
is
more than 3000 years It is made of wood,
old.
and
is
painted black and
The eyes are of colored stone. The gold.
claws are of
silver.
Peg
Two ways wood
-«
Peg
the ancient Egyptians joined small pieces of
learned to piece together small pieces of good wood,
They learned how
make plywood by gluing together thin layers of wood. They made many beautiful objects this way. The ancient Egyptians discovered that wood with resin in it burned slowly and very well. They made torches from resinous woods. The ancient Egyptians knew how to preserve joining
them very
carefully.*
to
animal hides by tanning them. Tanning changed the hides into leather. b
ning*
Oak
The Egyptians used oak
galls contain a lot of
galls for tan-
tannin (TAN-in), a
chemical that preserves hides.
The most important tree that grew in ancient Iraq was the date palm. It is still Iraq's most important tree. The people who lived in ancient Iraq used the date palm in hundreds of ways. They made furniture from its wood. They used its leaves for making ropes and mats. They ate its fruit. They also made wine from its fruit. They made charcoal from its fruit pits. They pounded the pits into
meal that they used
as flour
and
as food for cattle.
* For more information see Learning about Steel through The Story of a Nail by the same authors, The John Day Company, 1961. *° For more information see Insects and Plants by the same authors, The John Day Company, 1962.
14
A
chair
The
made 700
legs,
years ago.
arms and back were
turned on a lathe.
The Use During
of Trees:
this
From Ancient Times
to
1500
period people developed better ways of
wood and other tree products. They also developed new uses for wood and invented new tree products. Woodworkers learned how to bend wood by steaming it. Long flat pieces of bent wood were used for making
using
barrels.
Wood was
of chairs.
bent for making the backs and legs
Woodworkers
also learned
LAYTHE
Small pieces
on a lathe
(
)
.
how to turn wood of wood of a very
good quality were turned. They were used of chairs
as the legs
and couches. Woodworkers learned how
to
improve the quality of the wood they used by seasoning it.
The growing
up through out.
its
tree contains a lot of
roots.
Some wood
Freshly cut
also cracks
woodworkers learned how
if it
wood
it
shrinks as
draws
it
dries
dries too quickly. Early
to dry 15
water that
wood
slowly, or season
it,
before they used
it.
One way
by removing the bark from still
they seasoned
wood was
trees while the trees
standing. This exposed the water-carrying
to the air.
The
air
slowly dried
were
phloem
up the water.
many new industries developed. People learned how to make glass and developed better ways of making metals. Glass and metals were made in During
this
period
furnaces at very high temperatures. Charcoal was the fuel for these high-temperature furnaces. Charcoal
was
made from wood. During
Wood Oak
this
period people learned
how
to
make
soap.
ashes were used in soapmaking. galls
continued to be used for tanning leather.
Charcoal, a fuel made from wood, was used to heat the furnaces in which glass was made. 16
From As a
tree grows,
sunlight.
So
it
A
Forest Tree into its
forest tree
A
grows very close
forest tree
a long, straight trunk. trees
leaf-covered branches reach for
cannot spread outward.
for sunlight.
can be
made
The production
The
grows
is
room
way
for the
in height
and develops
of logs begins in the forest.
some
In this
can only reach upward
long, straight trunks of forest
which
trees are to
be
There a
some
cut. In
of the trees are selected for cutting.
These are usually the oldest fects.
It
to other trees.
into logs.
tree expert decides forests only
Log
the forest
younger
space for planting
new
trees or trees that is
thinned out so that there
trees to trees.
grow
well.
There
In the Douglas
however, whole blocks of trees are cut
Block-cutting of Douglas 17
have de-
down
fir
trees
fir
is
also
forest,
at the
same
A logger tree
cuts
down
a
with a power saw.
A
logger saws the tree up into logs. This is called bucking.
Douglas firs
of trees,
baby
are planted. In the cleared block the
baby
As soon
time.
firs
as the block has
can get the
full
been cleared
sunshine that they need in order to
grow.
Men saws.
called loggers cut
They
cut
them
down
as close to the
Then they remove all saw the trunk up into
is
They may be
ground
power
as possible.
the branches from the trunk and logs.
This
logs are then taken to a mill for use.
the trees with
is
called bucking.
where they are prepared
carried to the mill
a river nearby, the logs
may be
to the mill. 18
The
by
truck. If there
floated
downstream
From Log into Lumber are to be made into lumber
Logs that sawmill.
A
conveyor chain carries the logs to the top of
Each
a sloping platform on the sawmill floor. is
rolled
down
log carriage.
The
and forth along a
carriage rolls back
trimmings, called slabs, are carried
Then
log in turn
the slope and placed on the platform of a
metal track to a saw that trims the bark
belt.
are taken to a
the trimmed logs are
off
off
sawed
the log. These
by
a conveyor
into
rough lum-
ber.
Next, the rough lumber
which cuts with
its
off
is
carried to an edger sate
the lumber's rough edges.
edgings cut
off, is
wim
then cut into boards of
different lengths.
differ-
The edger saw cuts off the lumber's rough edges.
Trimmer saws cut the lumber into boards of
The lumber,
Wood
away at this time. The trimmed boards are placed on a pair of moving chains. As the boards are carried along by the chains, they are sorted by quality. The next step in preparing lumber for use is seasoning it. Some lumber is stacked out in the open air for seasonent lengths.
with defects in
it is
cut
KILLS
Other lumber
is
seasoned in dry kilns
a dry kiln, hot air
is
circulated around stacked lumber.
ing.
Lumber
that
is
kiln-dried can
may
Open-air seasoning
woods usually take longer
be seasoned
it is
in a
)
In
.
few days.
take several months.
Hard-
to season than softwoods.
The seasoned lumber then goes where
(
to a planing mill,
given a smooth surface. In the planing mill
the seasoned lumber
is
made
into flooring, siding, mold-
ing and other kinds of boards. Slabs, edgings
wasted. Sawdust factories that
and pieces is
make
of
wood with
not wasted either. other
defects are not
They
are sold to
wood products from them.
Other Uses for Logs Railroad tracks are supported by crossties. Crossties
wooden beams
may be made from
ern pine or Douglas
fir.
logs of oak, south-
Since crossties rest on the ground,
moisture from the ground makes them longer
if
Creosote
called
rot.
They
last
they are painted with a wood-preserving (
KREE-uh-soat )
is
20
a good wood-preserving
oil.
oil
that
is
made from
Telephone and
coal.
electric poles are
logs of southern pine that
preserving
Wood into
made
oil.
piling
is
driven into the floor of the ocean or
swampland and
100
from
have been treated with a wood-
bottoms to support
river
road bridges and even buildings. Piles as
chiefly
feet. Piling
pine and Douglas
is
fir
made mostly from that have
piers, rail-
may be
as long
logs of southern
been treated with a pre-
servative.
Smaller logs are
made
into fence posts.
Fence posts
are often treated with preservatives. Large branches are
cut into logs for firewood.
Logs are
also
made into wood pulp and plywood. See (
pages 25 and 32.)
These posts have
just
been treated with creosote. 21
Facts about
Telephone and
Wood
strong to be able to support the wire that
made from Douglas
them. Poles
are strong. Utility poles der.
Douglas
fir
must be
electric poles (utility poles)
must be
fir
is
strung from
and southern pine
tall,
straight
and southern pine produce
and
slen-
straight
tall,
bend a little in strong winds without breaking. Wood can bend and come back to its original shape. For this reason, we say slender logs. Utility poles must be able to
wood is elastic (uh-LASS-tick). So utility poles are often made of wood. Wood piling and railroad crossties the
must
also
Wood
be strong and
is
elastic.
light in weight. Its lightness
handle without very heavy ter
can easily
Balsa ness
wood
it
is
lift
the
lifting
wood he
makes
equipment.
it
A
carpen-
uses for building a house.
the lightest of woods. Because of
its
has been used for making airplane wings.
Maple
Walnut 22
easy to
light-
Wood
does not change
its
temperature quickly with
quick changes in the temperature of the
wood feels warm to wood is used a lot for So
do not
furniture.
is
around
it.
why wood
one reason
Houses made
of
lose their heat quickly in the wintertime.
Some wood is
the touch. This
air
is
easy to work with a carpenter's
easy to turn on a lathe. This
and cabinetmaking. furniture
Wood
made
direction in
in the
which
its
is
good
for furniture
with a nice grain
and cabinetmaking,
the pattern
wood too.
The
tools. It
is
grain of
good
for
wood
is
wood by its growth rings and the wood cells grow. The grains of
maple, walnut, oak and cherry are shown below.
Some wood has unusual qualities that give it special uses. The tree lignum vitae (LIG-num VY-tee) is very hard. Moving parts made from it never need oiling. It is used to swells
line the propeller shafts of ships.
when
it
gets wet, so
it is
Oak
used
Teak hardly
in shipbuilding.
Cherry 23
Wood
Charcoal from
When wood burns the
wood produce
in the
open
gases driven out of
air,
flames and smoke. After the gases
have burned up, the flames and smoke die down. The
wood wood
shrinks is
and turns
black. This wrinkled charred
charcoal. It burns with almost
gives off a great
amount
burns up and the
fire
Burning wood
no smoke and
of heat. Finally the charcoal
goes out.
open
in the
air is
not a good
way
to
make charcoal, because then the charcoal burns up, too. One way of making charcoal is by burning wood very slowly in a kiln. The wood burns slowly because hardly any air passes through the kiln. The slow burning forces the gases out of the wood. The gases do not catch on fire but pass out through an opening in the
were made by covering a kilns
were made
of brick.
pile of
kiln.
wood with
They were
Early kilns
earth. Later,
called beehive kilns,
because of their round shape. Small portable beehive kilns
have been made of sheet metal. Kilns are made of
concrete and fieldstone, too.
Charcoal (
is
usually
made now by
C AR-bun-ih-ZAY-shun
in
an
airtight
Baking drives
made
oven and off
)
method. The wood
is
baked
at a
is
placed
high temperature.
the gases, which are collected and
wood by-products. The baked wood becomes The carbonization method of making charcoal
into
charcoal.
the carbonization
24
^^^{gi^54*^^^
Charcoal making 400 years ago. The man is heaping logs on the pile at the right. The pile at the left is covered with earth. The wood inside this pile is burning slowly. is
better than the kiln method. It takes less time than the
kiln
method. The gases and
tars are
made into other products. One of the most important
uses of charcoal today
as a cooking fuel for barbecues.
cues
make
is
usually
made
briquettes,
first
not wasted but are
Charcoal used in barbe-
into briquettes
a paste
is
is
(bri-KETS). To
made from crushed wet
Then the paste pillow-shaped briquettes by a press-
charcoal and cornstarch or potato starch. is
formed
into small,
ing machine.
The wet
briquettes are then dried in an
oven.
Plywood
The Egyptians made plywood because they had very little beautiful wood. They were able to produce beautiful wood surfaces for cabinet work by gluing a thin sheet 25
(vih-NEAR)
or veneer
to a piece of ordinary
make plywood
of
wood with
a beautiful grain
wood. Like the Egyptians, we
to put a nice
also
veneer surface on ordinary
wood.
We
make plywood because plywood has many that lumber does not have. Plywood is made
also
qualities
by gluing together three or more
The
grain of each ply
next to ing.
it.
laid across the grain of the plies
is
usually
made with an odd number
of
(WARP-ing)
or
This keeps plywood from warping
bending by
itself.
formed more to use for
wood
is
wood.
This keeps plywood from swelling and shrink-
Plywood
plies.
is
plies or layers of
However, plywood can be shaped and
easily than solid
curved surfaces
much
ness. Panels of
wood. This makes
like chair
backs and
good
it
seats. Ply-
stronger than lumber of the
same
plywood can be made much
larger than
pieces of lumber
sawed from
logs.
thick-
This fact makes build-
ing with plywood faster than building with lumber.
The tree
is
story of
cut
plywood begins
in the forest
down and the trunk is trimmed
At the plywood factory the trunk will is
fit
is
of
off
the logs and the logs
makes veneer cutting on a rotary of veneer
lathe.
comes
easier.
The off
branches.
cut into lengths that
into the veneer-cutting machines.
taken
its
where the
may be
Then
the bark
heated. Heating
Most veneer cutting
picture shows
how
is
done
the thin sheet
the log as the log turns against the 26
Log on a rotary
lathe
The
cutting blade of the lathe.
sheet of veneer
cut into pieces. Pieces with defects are cut time.
The trimmed
is
away
then
at this
pieces are dried. After drying, the
pieces are joined together to
make
full-size sheets of
veneer. Both sides of each veneer sheet are then coated
with glue. Waterpoof glue that
is
to
is
used for making plywood
be used outdoors. The glued sheets are assem-
bled so that the grain of each sheet grain of the sheets next to are placed in a hot press.
hot press
make
is
laid across the
Then the assembled The heat and pressure it.
sheets of the
the glued sheets stick to each other,
forming a plywood panel. After the plywood panel leaves the press,
it is
sawed
to the right size
and sanded.
Panels are usually sawed so that they measure 4 feet by 8 feet. Panels measuring 40 feet have been special purposes.
27
made
for
Other Man-made Building Materials from
Wood
(LAA-mu-NATE-id) wood — Laminated wood is wood that is made by gluing together many layers of wood. The grains of the layers usually lie in the same direction. Each layer is made up of many small pieces of wood that have been glued together. The pieces of wood are seasoned before they are glued. This keeps laminated wood from cracking and shrinking. Using lamLaminated
inated wood, great arches and rafters for supporting roofs can
be made from small pieces of wood. Some of
these arches are
more than 150
— Hardboard
feet long.
man-made board made from wood fibers. The fibers are made by exploding wood chips with steam. The fibers are made into a wet mat that has about the same size as the finished hardboard panel. The wet mat is then placed in a hot press where heat and pressure press the mat of fibers into a thin hard sheet. The fibers are held together by the lignin in them. Because hardboard is made from wood chips, hardboard can be made from healthy pieces of wood of Hardboard
any
size.
a
Sawmill trimmings are often used
hardboard. Hardboard also
is
is
in
making
used as a wall paneling.
It is
used for making cabinet backs, drawer bottoms and
counter tops. Particle
(
P AR-tih-kul board )
28
— Particle board is a build-
Laminated wood used making the head of
for
a golf club
Laminated wood arches
Papreg
in
tube form
sheet and
.
ing material that
made from
is
are held together
by
wood
small bits of
that
which they have
a chemical with
been mixed. Particle is
board
faced with
used as a wall paneling. Sometimes
is
wood veneer or hardboard. Wood
sawdust and other sawmill leftovers are used
it
shavings, in
mak-
ing particle board.
Modified (MOD-ih-fide) tcoods
means
to change.
Wood
crack, shrink, swell,
when
it
ture.
Wood
gets
cells
modified so that
or
change
ing pressed at the
with a
Wood
same time
is
is
in
will not
way
tempera-
empty spaces
Modified
resin.
that
wood
When
which has been
modified without be-
called
impreg
(
IM-preg)
layers of veneer are modified is
called
under heat
compreg (COM-
and knife handles are sometimes made out
preg. Tool
compreg.
If
sheets of paper are treated with resin
then modified under heat and pressure, a product sults that is
known
as
is
used for making patterns for automobile
is
and pressure, the product
of
the
filling
it
shape in any
its
of veneers, each of
treated with a resin.
bodies.
is
modified by
is
made up
Impreg
word "modify"
wet or when there are changes
around the wood usually
warp
— The
very strong and
is
papreg (PAY-preg).
tubes and pipes.
It is
and re-
lighter than metal. It It
is
can be bent to form
used for paneling walls and coun-
ter tops.
30
The tub is filled with a mixture of water and shredded rags. A thin layer of rag pulp covers the screen. The man shakes the screen while the water drains
off.
Making paper by hand 400 years ago
The Early History
of
Until about 150 years ago paper
Paper
was made by hand
way the Chinese had made it 2,000 years earlier. It was made mostly from linen and cotton rags and cloth. The rags and cloth were shredded and beaten into a pulp of linen and cotton fibers. The pulp was then mixed the
with water.
A thin
layer of the
a wire screen and the water
wet pulp was spread over
was allowed
to drain off.
The screen was shaken while the water was draining to make the linen and cotton fibers stick together to form a mat. When the thin layer of matted fibers had dried, it was a piece of hand-made paper. Making paper by hand took a lot of time. So paper was very expensive and not very much was made. The first paper-making machine was invented in 1798. Even though paper could then be made in less time, there
was
a shortage of paper because linen
still
The paper shortage ended making paper from wood was dis-
and cotton rags were
when
a
covered.
method
of
scarce.
The Story
of
Wood
Pulp
The first step in making paper from wood is to make wood pulp. Wood pulp is wood that has been broken
a
down
so that
its
cellulose fibers are separated.
made from the softwoods — pine, spruce, hemlock and fir. It is made from sawed logs and from sawmill slabs and other trimmings. The first step Most wood pulp
in
pulp-making
is
is
to
remove the bark from the
logs.
There are three ways of making wood pulp. Each
own kind of paper. One way of making wood pulp is by cooking
method produces
its
the
wood
with certain chemicals. First the peeled logs are cut into
The wood chips are then placed in a huge vat called a digester. The digester cooks the chips and chemicals under pressure. The chemicals dissolve the lignin and resins in the wood. The chemicals, lignin and small chips.
removed, leaving a pulp of almost pure
resin are then
cellulose fibers.
Pulp made
pulp. Chemical pulp
is
in this
made
also
A
is
for books.
Chemical pulp
used for making plastics and man-made
second way of making wood pulp
peeled logs of stone.
called chemical
into good-quality writing
and wrapping paper and paper is
way
The
wood under water
cellulose fibers are
is
by grinding
against a rough grind-
ground
off into
along with the lignin and the resins. Pulp *
*
fibers.
the water
made
in this
For more information see Fibers by the same authors, The John Day Company, 1964.
32
Wood at a
Peeled logs on the way to the chipper
Chips being carried
to
^
|fe»
X
the digester
Digester
Making chemical pulp
1^
for pulp arriving paper mill
way
is
called groundtvood pulp, because chemically
no different from wood.
called mechanical pulp
made by the mechanical method of grindPaper made from mechanical pulp is very weak.
because ing.
It is also
it is
it is
Newsprint, the paper on which newspapers and some
made mostly from mechanical chemical pulp is added to make the news-
magazines are printed,
A
pulp.
little
is
print stronger. Newsprint
A
way
is
a very inexpensive paper.
making pulp
partly chemical
and
partly mechanical. Peeled logs are cut into chips.
The
third
wood
of
chips are softened a
little
is
by cooking them with
mild chemicals. The softened chips then pass between a pair of quickly spinning plates that
pulp. Pulp (
made
Semi means
change them into
way is called semichemical pulp. Many kinds of cardboard cartons are
in this
half.
)
made from semichemical
pulp.
Paper
fiber
tubes
made from chemical
m
pulp
A
pulp beater
y. S. 1386i3 ;>
Paper from Chemical Pulp Before pulp
is
made
into paper,
it
must be thoroughly
washed, cleaned and screened. The pulp spraying of a
huge
it
with water as
cylinder.
it
is
washed by
turns around on the outside
Washing removes any chemicals and
other materials that stick to the cellulose fibers after they leave the digester. Cleaning and screening remove dirt
and uncooked wood chips and separate the
fibers
by
Then the pulp is bleached to make it whiter. The pulp now passes on to a large tank called a beater. Water and pulp are mixed together in the beater. If the size.
35
A
mixture of water and pulp
The dried paper
is
is
run onto a moving screen,
wound up 36
in
a huge
roll,
pulp
is
being
made
into colored paper,
dye
is
added
to
the mixture in the beater. Certain chemicals are also
added
to the mixture in the beater to size paper. Sized
paper doesn't soak up liquids
on with pen and
ink.
easily, so
it
can be written
The pulp may then go on
The refiner rubs and them shorter. Shorter
to a re-
finer.
cuts the cellulose fibers,
ing
fibers
When finer,
as
more water
is
added
until the mixture has
as pulp. This
watery mixture then goes
onto a long, wide moving belt,
made
As the screening moves along
side to side.
together in drains
The
run
of fine wire screenit
also shakes
from
The shaking makes the cellulose fibers stick a mat. At the same time, some of the water
sheet of wet pulp
is
carried through
many
pairs
which press out more water. Next the sheet
travels over a series of hot cylinders
A
is
off.
of rollers
ing.
99 times
paper-making machine. The mixture
to the
ing.
finer paper.
the mixture of water and pulp leaves the re-
much water
on
produce a
mak-
half-mile of paper
in a minute.
may
finish the dry-
pass through the dryers
wound up in a roll. Rolls paper-making machine may measure 25
The dried paper
that leave the
which
is
feet across.
The
large paper rolls are usually cut into smaller rolls
or into sheets before they are sold. 37
Naval Stores In the days of
wooden
sailing ships, supplies of tar
always had to be on hand. Cracks between the wooden boards of a ship were waterproof.
with tar to
The ropes that held up the sails were treated keep them from rotting. Because tar and
products related to in
it
were used mostly
has
many
Naval
resin
keeping ships
leaf
and
produced by
is
woody
and pan are nailed
which grow
layer
is
The
South are the
A
to the tree just
still
standing
long, crosswise slash is
removed and
A
layer of tree shows.
metal gutter
under the
slash.
Then
sprayed with an acid. The acid makes
the gutter into the pan.
made about
steady flow of gum. barrels
States the long-
in the
slashed bark
the oleoresin begin to flow.
ones, are
made from
of oleoresin.
in the bark.
woody
are
collected from trees that are
the outermost
the
They
trees in the pine family. Oleo-
without damaging them much.
made
This
called naval stores even though
gum. In the United
slash pines
main sources
Gum
stores.
other uses today.
also called
is
is still
stores are tree products.
oleoresins
is
for
good condition, they were called naval
family of products it
with tar to keep the ship
filled
New
The
slashes, just
down
above the old
every two weeks to keep up a
The gum
which are taken
oleoresin flows
is
collected in
to a distillation
38
(
wooden
DISS-tuh-LAY-
shun) plant.
Gum
from the stumps of resinous
have been cut down
is
also gathered to
trees that
be used
for
mak-
ing naval stores.
The
chief products
made from and
tion plant are turpentine for thinning paint. It
Turpentine is
used to
violin
is
also
is
used
size paper. It
bows
to
oleoresin at the distilla-
rosins.
Turpentine
used in making paste
used
waxes.
making some medicines. Rosin
in is
floor
is
rubbed over machine
keep them from
belts
and
sticking. Baseball players
rub rosin over their hands so their hands won't stick to the bat or the ball. Rosin
and printing
inks.
Gutter and pan for collecting oleoresin
Spraying with acid to make the oleoresin flow
is
also
used
in
making paints
Sap Before the white
knew
We
Use
man came
North America, the
to
wounds in certain maple trees had a sweet taste. They even knew how to make sugar from the sap. Today the maple sugar Indians
industry
that the sap that flowed from the
an important farm industry in the North-
is
eastern part of the United States.
the industry
The raw material
of
the sap of the sugar maple or the black
is
maple. In the sugar maple and the black maple, sap
moves
through the xylem in the springtime under great pres-
The pressure
sure.
in the
than the pressure of the tree. If a
hole
is
made
xylem
time
at this
air against
is
greater
the outside of the
into the xylem, the sap will flow
through the hole to the outside. Farmers make use of fact
when they
tap maple trees in the early spring.
Farmers tap maple the xylem.
A
this
trees
by
drilling a
few holes
metal spout, sometimes called a
into
spile, is
placed in each taphole. The spout works like an open faucet through which the sap can flow.
hung under each spout
bag
is
The
pails or
The
it is
to catch the flowing sap.
collected sap
made
products. In very
many
pail or plastic
bags are emptied several times a day into
large buckets.
house where
A
is
taken to the sugar-
into syrup, sugar
and other maple
modern sugar bushes (woods with
sugar or black maples ) the sap 40
is
pumped through
Hanging a
pail
under a spout
Bringing the sap to the sugar house 41
plastic tubing
from the taphole right
In the sugarhouse the sap in the sap
thicker.
is
driven
The
sap,
As
which was pale yellow
Maple syrup
syrup.
boiled.
boils,
it
water
and the sap becomes sweeter and
off
brown. The sap
light
is
to the sugarhouse.
is
boiled until
it
in color, turns
becomes a thick
used as a flavoring. Further
is
boil-
ing produces a thicker mixture which can be used as a spread.
what in
When
is left is
almost
maple
molds or cut
all
the water has been boiled
sugar.
Most bark.
trees
The
We
candy.
Use
form a layer of cork on the outside of the
waxy
walls of the cork cells have a
material in them. This
and
Maple sugar can be shaped
like fudge. It is a
Barks
airtight.
off,
makes the cork
The cork oak
cells
or fatty
waterproof
that grows in countries near
Cork when
is
stripped off
the cork oak
about 25 years
is
old.
New
cork cells grow forming new layers of cork.
These new
lay-
ers are stripped off every 9 years.
42
the Mediterranean Sea produces very thick layers of cork. Its cork cells are filled with air.
of the cork
oak
cause the cork
and
airtight,
made
is
many
into
cells are filled
with
Cork from the bark
useful products. Be-
air
and are waterproof
cork floats easily in water. So pure cork
used to make
life
jackets
makes cork a good
and
floats.
The trapped
air
Cork
insulating material, too.
is
is
crushed and mixed with other materials to make insulation
board and
floor tile.
The cork cells in the bark of some trees have tannin in them. The bark of the hemlock, chestnut oak and quebracho (key-BRAH-cho) has a lot of tannin in it. The extracted from the bark of these trees and
is
used for tanning leather. Tannin for making leather
is
tannin
is
also extracted
from the wood of the chestnut and the
quebracho and from the leaves of the sumac.
The bark
cells of
liquid called latex
may be
tapped.
(
The
some
trees
L AY-tex latex
is
)
.
produce a
sticky,
milky
Trees that produce latex
then gathered and
is
manu-
factured into rubber/
The
outside bark of the cinchona (sin-KO-na) tree
that grows in the
Andes Mountains
contains a chemical called quinine is
(
in
South America
KWY-nine
)
.
Quinine
used as a drug to treat the disease malaria. The white
pine, cherry
and witch hazel are some other
trees
whose
barks are used for making drugs. *
For more information see Fibers by the same authors, The John
Day Company,
1964.
Walnut
Apple
Some
fruits
we
each
eat. Part of
away
cut
fruit is
to
show
the seeds.
We
Fruits
The its
fruit of a tree
is
Use
the part of the tree that contains
seeds.
In a conifer, the fruit
the cone.
is
conifer are on the scales of the cone.
decorations. Craft shops use
them
for
The
seeds of the
Cones are used
making
as
novelties.
Cones are used on Christmas wreaths. In a broad-leaved tree, the fruit consists of a seed or a
group of seeds with
its
the protective covering
protective covering. Sometimes is
fleshy, as in the apple, the
cherry, the orange or the peach. fleshy coverings.
We
eat
some
of these
Sometimes the protective covering 44
is
hard and stony or woody. These hard as nuts.
We
some
eat the seeds of
Oils are extracted or taken out oil,
fruits are
nuts.
from
fruits.
Coconut
extracted from the fruit of the coconut palm,
in
soapmaking. Oil from the
is
used for making candles. Oil from the
cacao (kuh-KAA-oo) tree butter and cocoa. Olive
the olive tree. Olive
cooking
oil.
also
It is
fruit of the
made
is
oil is
African
used
is
oil
palm
fruit of the
into chocolate, cocoa
extracted from the fruit of
used as a salad
oil is
known
oil
and
as a
used in the manufacture of some
soaps and drugs.
Lignin
For the papermaker, lignin dissolved and will
be made
removed
is
a nuisance.
It
must be
to free the cellulose fibers that
into good-quality writing
and book paper.
Lignin that has been separated out in papermaking is
made into
useful products.
lignin useful in the
Its
binding properties make
manufacture of cement products and
animal-feed pellets. Lignin that has been separated out
oil wells.
Lignin in the
muds that are used in drilling muds keeps the drill points from
sticking.
Lignin
used
in
papermaking
is
added
is
also
to
Artificial vanilla flavoring
in leather tanning. is
made from
lignin.
Re-
cently a chemical containing lignin has been used as a
drug.
The drug
is
used as a
painkiller.
45
Trees for the Future
One
half of the land area of the
ered by forests.
Now
world was once cov-
only one third of the land area has
man
a forest cover. Forests have disappeared because
has been thoughtless.
he burned
Man
forests to clear
has been thoughtless
them
when
Man
for grazing.
has
been thoughtless when he cut down
trees to clear fields
new
trees in their place.
for
farming and has not planted
As a
result of
man's thoughtlessness,
do not have enough
trees to supply their
lumber and other
tree
enough
products.
trees to prevent floods
many
countries
needs for paper,
They do not have
and conserve
their supply
of water.
In countries that
still
have a good forest cover, the
people must use their forests wisely. They must plant more trees than they cut down to provide tree products .;***
for their
growing populations. In countries where
forests
have been destroyed by thoughtless burning, clearing
and grazing, the
first
task
is
great tree planting programs.
to rebuild the forests
Then
the world will have
a forest cover that can meet the needs of of the
by
all
the people
world for tree products. Then the world will have
a forest cover to help prevent floods
water supply.
and save the world's
Word
List
Cambium (KAM-bee-um) — A
layer of cells just under-
neath the phloem from which
phloem Cellulose
up the
cells are (
formed.
SELL-yuh-lohss )
cell
new xylem and new
— The tiny fibers
wall of a plant
Conifer (KON-uh-fur)
—A
that
make
cell.
tree that produces
its
seeds
on cones. Conifers are usually evergreen. They are
also
called softwoods.
Cork
—A
layer of cells
on the outside of the bark. The
walls of cork cells have a
them
makes cork
that
waxy
cells
waterproof and
Deciduous tree (dih-SIJ-yuh-wus) leaves each year
Fruit
— The
airtight.
— A tree that loses
and grows new leaves the next
its
year.
part of a plant that contains the seeds.
Lignin (LIG-nin)
woody
or fatty material in
— The chemical inside the cell wall
of
plants that holds the fibers of cellulose to-
gether.
Phloem
(
FLOW-em — A )
layer of cells inside the stem
that carries sap from the leaves to
all
parts of the tree.
— A chemical that preserves hides. Veneer (vih-NEAR) — A thin sheet of wood. Wood pulp — Wood that has been broken down so that Tannin (TAN-in)
its
cellulose fibers are separated.
Xylem
(
ZY-lum )
carries sap
—A
layer of cells inside the stem that
from the root
to all parts of the tree.
9^*
About the Authors
Ruth Adler have
Irving and
written
more than
sixty
books about science and mathematics. Dr. Adler has
been an instructor sity
and
of the
at
in
mathematics
Columbia Univer-
at
Bennington College, and was formerly head
New York City high
mathematics department of a
school. Mrs. Adler,
who
formerly taught mathematics,
science and art in schools in the
New
York
area, recently
also taught at Bennington. In addition to
working with
her husband writing this book, she has joined with him
on 26 other
titles in
the Reason
the illustrations for most of
other books written
Why
them
series
and drawn
as well as for
many
by him.
Books by Irving Adler alone and books by him collaboration with
Ruth Adler have been printed
different foreign editions, in 14 languages
and
in
in
83
in 10 re-
print editions.
The Adlers now
live in the
Town
of Shaftsbury, near
Bennington, Vermont.
PHOTOGRAPH CREDITS Pages 19, 27, 29, 32, 36 - American Forest Products Industries Page 42 — Armstrong Cork Company Pages 1, 10, 17, 18, 21, 22, 23, 29, 34, 35, 38, 39, 46, 47 - U.S. Forest Service Page 41 — Vermont Development Department
48
The
WHY
REASON
Books
by
Irving
and Ruth Adler
"They are excellent"— New York Herald Tribune
"The best of the matter is that, with authors like the Adlers, their name is a guarantee. One can be certain that not only is the exposition clear and logical, but that the scientific — The Horn Book Magazine matters presented are correct and up-to-date."
EVOLUTION "The Adlers present
their
all
books with great
young readers
simplify difficult matters for
.
.
.
scientific
accuracy and have the ability to
Well presented and
interesting."
—Catholic Library World
COAL "Described in this interesting, well -written text are the uses, origin, mining processes, and chemistry of coal. Pictures of methods and equipment are particularly useful." —Library Journal
THINGS THAT SPIN "A
helpful
— The Horn Book Magazine
and stimulating book."
SHADOWS "An
easily
understood explanation of the causes and uses of shadows."
—ALA Booklist
NUMBERS OLD AND NEW "A
fascinating book for the student interested in mathematics."
—American Library Association "Exceptional book about
how we came to count as we do." —Child Study Association of America
WHY? A "I'd suggest that
it
be given
to a child
collecting unrelated facts."
Book of Reasons with an inquiring mind and acquisitive instinct for —Virginia Kirkus
AND PLANTS
INSECTS "The
interrelation of plants
trations in
two
and
insects, for the
colors."
middle grades. Attractive and useful illus—The Horn Book Magazine
ATOMS AND MOLECULES "Successfully aiming at the eight-to-ten -year-olds, the Adlers introduce chemical symbols
and chemical formulas
.
.
.
even a
bit of
nuclear chemistry."
—The Horn Book Magazine
FIBERS uch needed, factual book on wool, rubber,
silk, fiberglass,
and man made, this includes flax, cotton, and numerous other less common ones." —Library Journal
fibers, natural
nylon, rayon,
HOUSES "In keeping with others in the series, this survey of dwellings simple. Recommended."
_,
JOHN DAY,!
*
CMMNTCE9 o
is
comprehensive, clear and —Libraru Journal