Evening public ledger. [volume] (Philadelphia [Pa.]) 1914-1942, 1919-03-25
n TROPICAL WOOD
LIGHTER THAN CORK
Ho,o the Necessities Of Var Forced
Its Use in Life Rats, Mine
Buoys and AirpLanes


MANY years ago a manufacturer Of life
Av1 saving appliances at sea was sailing in
the tropics. When Off the coast OF Ecuador
he noticed that the natives used logs of a
very light wood for making RATS. Upon in.
quiry he learned that the wood was known
as balsa, which is the Spanish for raft, and
he was told that the tree was one of the
commonest second.growth trees in the trop-
ical jungles. The botanical name for 1t is
Ochromd ld1opuS. The tree resembles in
appearance the North American cotton
wood. The bark is smooth and the wood
looks like clear white pine. The leaves of
the young trees are very large, often from
two to three feet across, but they grow
smaller the tree increases in size. Bios
SONS appear when the tree is about three
years old. They emerge from green buds
standing upright like candles When the
flowers fall the seed pod develops till it is
about six inches long and one inch in di-
ameter, and when the seed IS ripe the pod
bursts, releasing large quantities of golden
brown cotton. A single pod yields enough of
the fluffy stuff to fill bushel basket. 1t is
used by the natives for stuffing pillows
and mattresses.
AS the tree grows continuously there
are no annual rings in a cross section.
And it grows rapidly that a tree of
from twenty-four to thirty inches in di-
ameter can be raised from the seed in
five or six years. 1t Is the lightest known
wood. for a cubic foot of it weighs only
7.3 pounds, whereas cubic foot Of cork
weighs 1871 pounds and the same amount
of spruce tips the scales at twentyseven
pounds. Quebrache, the heaviest known
wood. weighs ninety-one pounds to the
cubic foot. Balsa is surprisingly strong.
considering it's lightness. Tests made at
the Massachusetts Institute of Technology
showed that it would bear about half as
much weight as spruce before it broke.
FTNHE commercial use Of balsa had to wait
L until some way was invented to pre-
vent it's rapid decay. A method Of water
prooflng which would force a chemical
mixture to the center of any piece of
timber was tried on balsa and it was found
that it covered all the cells and ducts with
permanent air and waterproof film and
prevented decay. This happened before the
war. So when it was necessary to supply
the transports with lferafts and to make
buoys to support the floating mines in the
North Sea the government demanded balsa
wood RATS and buoys. More than 10000
of the RATS were delivered within seven
months. And the use of the wood to float
the mines made the mine barrage across
the North Sea possible. No other sub
stance used for the buoys would with
stand the long submerson or the shock
of the depth bombs.
FNHE demand for the wood became so
L great that experts were sent to Central
America and Ecuador to discover new
sources Of supply, and the government Sc
cured the services Of Prof. w. w. Rowles
head of the botanical department of Cornell
University, to educate the growers in the
best methods of cutting the trees. He
made exhaustive studies of the ways Of
planting and propagating balsa, and as
result Of his investigations great forests
are to be planted to supply the timber
needed for future use.
The lightness of balsa suggested expert
mentation with it's use in airship construc-
ton. Wing braces Of it veneered on both
sides with fiber board one thirty.second Of
an inch thick and cut into lattice web
have been built up into I-beams by the
addition Of quarter-inch strips Of spruce
an inch wide. One of these beams five
feet long weighs only one and half
pounds and it will hold a load Of $50
pounds on it's center. A spruce beam Of
the same size weighs much more and will
support only 500 pounds.
OWING doubtless to it's rapid growth
~ there is almost no woody fiber in balsa
A log of it is virtually pure cellulose Now,
cellulose is an excellent insulating material
because it conducts neither heat nor cold.
Tests with balsa have shown that its insu-
lating power is greater than any other
material in commercial use. 1t can be
used in ice boxes, refrigerator cars and
refrigerator ships. It's lightness would re-
duce the weight of refrigerator cars per-
ceptibly and would increase the cargo
carrying capacity of ships.
THE expansion of the uses OF this tropic
L wood through the necessities of war is
one Of the compensations Of the great con-
flict. 1t was known prior to 1914 just as
the airship was known. Navigation Of
the air has been advanced more nearly to
perfection in the last five years than in
all the preceding centuries since Icarus
and his father flew from Crete and the
adventurous youth went so near the sun
that the wax holding his wings to his
shoulders melted and he fell into the sea-
We know more Of chemistry than we did in
1914 because the chemists, driven by neces-
sity, have discovered new gases and new
combinations of old gases They have even
been able to extract argon from the air
| for initiating balloons and have thus made
| available gas of much greater buoyancy
than hydrogen and much more enduring
War has also proved the practicability of
the fabricated ship and Of the great gun
with a range Of seventy.five miles. 1t has
| perfected the submarine and the, depth
bomb and the microphone as means for
| destroying the undersea ships. But com.
mercially 1t has done nothing more inter.
esting or Of greater moment than the de-
| velopment of the many uses for little
| known and hitherto useless tropical tree.
We may in the near future be riding in
automobiles with bodies made Of balsa in
stead Of aluminium or pressed steel.