The San Francisco call., 1904-02-27
AbOnt asbestos.
BY MALCOLM MCDOWELL.

tAuthOr shop Talk on w hOnQers OF the
Crafts.")
Copyright, 1904. by Joseph B. Bowles)
Asbestos, one of the most wonderful
of substances dug out of the earth, has
been much in the public eye since the
IrOquois Theater disaster. Now, it is
reported, the bulk of the worlds sup
ply for many years to come has been
secured by the Standard Oil interests
for the purpose of making freproof
timber and tunnel sheathing.
The supply Of asbestos is limited.
Most of it comes from Canada, and it
is found in Oregon, Idaho, California
and other Western States. 1t also is
mined in the Italian Alps, whence
most of the supply came before it was
discovered in Canada. But, except in
the later country, the veins of the
greasy-feeling, silky-like fibrous stuff
are too thin to be worked with profit,
for the problem of mining asbestos is
found in the disposition of the foreign
matter in which the asbestos is en-
tombed. In the Canadian mines only
about per cent of the material quar-
ried is asbestos; the rest is made up of
rock and other refuse.
Asbestos occurs in veins, varying
from half an inch to four inches thick,
between layers of hornblende crystals.
The longer, tougher fibers are found in
the deepest diggings; the less valuable
asbestos-that is, the short, easily pull
verized fibers-are found near the sur
face. The mining is much like rock
quarrying. Holes are drilled and
dynamite exploded to blast out layer,
which falls to the floor of the work.
ing. The workmen break out as much
OF the pure asbestos in as large Jumps
as possible, load the Jumps into tubs
or skips and send it to the surface,
where boys and young men cob" or
crumble the rock away from the as
bestOs.
The Jumps of asbestos are packed in
rough bales and shipped to this coun-
try to be manufactured into the fin
ished product. The asbestos as 1t
comes from the mine is of yellowish
or greenish color, the edges furred
with loose fiber. The best grades Of
asbestos are white, and the fiber is
long enough to be carded and spun
into yarn and then woven into a
greasy-feeling, dirty white cloth,
which is fireproof, acid proof and
weather proof.
When the Jumps of raw asbestos
reach the factory they are placed into
machines, which crush them until the
fbers are lOosened into fluffy, cottony
masses. From the crushing mill the
hbers pass into another machine which
separates the long and short fibers and
at the same time throws out any stones
or other refuse matter. The short fibers
are ground up into a pulp or powder,
according to the use for which they are
intended, while the longer fibers are
gathered together TO be woven into
cloth.
1t is this cloth which is used for max
ing fireproof drop curtains for thea
ters. The asbestos yarn also is made
into gloves and mittens for glass and
iron workers and a finer cloth is woven
for acid filters. To catalogue the uses
of asbestos would be a long task, for
within twenty years its applications
have multiplied so rapidly that ii now
can be regarded as one of the most
versatile of manufactured products
Combined with colors and oils it makes
a paint which makes anything it coats
either fireprOOf or nearly so. Asbes-
tos, combined with canvas, felt or like
material makes an excellent roofing
or ceiling material and the roofs of
many factories, warehouses, docks and
like structures are covered with asbes-
tos treated material. Wood pulp or
other substances which can carry the
asbestos is used for covering steam
pipes.
Mineral WOOL is the nearest thing
to asbestos which man has been able
TO make on a commercial scale. AS
first it was made from Stag, the refuse
from blast furnaces, but the wool
was too brittle and melted at too low
a temperature to be used as a sub
stitute for asbestos. Metallurgists took
the matter in hand, analyzed asbestos,
and made up the proper mixture from
sand, fire clay, limestone, kaolin and
iron Stag to give a product which pos
sessed many of the characteristics OF
asbestos. Now limestone, broken glass,
broken dishes, iron Stag and pieces of
fire brick are melted down in a suit
able furnace and blown into the fibrous
stuff called mineral WOOL"
When the mixture is melted into a
liquid by the intense heat of the fur
mace small opening is made and the
molten stuff escapes in a stream about
an inch in diameter. AS it falls a Jet
of steam or compressed air, issuing
from fiat noZzles, is turned on to il
and blows it, a fine spray, through a
window into an adjoining room. The
action of the jets upon the stream of
molten sand, iron, clay and glass spins
it out into beautiful white fibers. which
on cooling look like washed wool. This
material is used largely as a non-con-
ductor of heat. 1t is packed around
Steam pipes and boilers to retain heat
and packed around refrigerators to re-
! tain the cold. II also is used for fire
proofing" buildings and for ''deadening''
walls and floors. but compared with as
hc- &C.