Perth Amboy evening news., 1923-12-13
HASKLN,S
LETTER
COUNTING TILE DUST IN THE AIR
BY Frederic j. Haslxin

reau. EVERY Qay recOTuS VI Ilc
amount of solid material suspended
In the air are made at a laboratory
In Washington. Dust counts have
also been made in other cities, and
the upper air has been tested from
the Washington monument and by a
series of records made from air
planes.
The importance of dust has been
steadily gaining recognition in re-
cent years. The bureau of chem
istry gives a good deal of attention
to the study of dust explosions and
e of preventing them. Dust
laden air. especially in some kinds
Of mines and Industrial plants, is
now known to be a possible menac
to health, and the bureau of mines
and the department of labor warn
workers in certain occupations
against hazards of the air, and ex-
plain precautions to be taken against
them.
Soil experts and students of
weather conditions find evidence that
a single storm may transport a mil
lion tons of fine rock material a
thousand miles or more A violent
volcanic eruption sends tons of dust
into the air, where it may drift
about for two or three years, rising
as high as fifty miles in the air, and
travelling around the globe several
times. Krakatoa, which erupted in
1888, distributed so much dust into
the air that the rays of the sun
were intercepted. Some scientists
claim that the unusually cool
weather of that year was due to
the effects of dust from the great
volcanic explosion.
The weather bureaus research has
two definite aims. One is to help
the aviator, to whom dust is the
most important meteorological fac
tor. The other purpose is to collect
data which may show more plainly
dangers of certain kinds of dust in
the air about us.
The dust counting project is going
forward in the United States and
in eleven other countries, 1t was
started in 1922, when an i%nterna-
tional scientific conference in Rome
agreed to buy twelve dust-counting
instruments. One instrument was to
be furnished to each country that
would devote enough time to the
business of dust-counting to draw
some enlightening conclusions.
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Interest OF scientists at the on
ference was stimulated by the sug-
gestion that perhaps evidences OF
cosmic dust, waited to earth from
space, might be revealed by the in
v-estigations. DIR. II. II. Kimball,
who is in charge of the work in
this country, has found no speci-
mems of cosmic dust.
He says that il the earth encoun-
terrell a cloud of cosmic dust, the
cloud would surround our planet
and each one of the international
lust counting stations would find the
evide C in the air at about the
same time. In the case of dust
which fellows a volcanic explosion,
the characteristic particles reach
different regions at different times,
as the material is carried along by
air currents.
Dust brought to earth from an
other planetary body outside our at
m~osphere would probably be of ma
terials no different from those OF
earthly dust. The cosmic grains
would be identified mainly by shape.
They would be spherical, worn
smooth by friction in their long
journey, Instead of having jagged,
sawlike edges, such as tiny grains
of sand or coal dust have. Dust
of meteors is found, of course.
About a hundred tons of meteoric
material, which is@ mostly iron,
reaches the earth's atmosphere every
day, and much of this Is dust before
it comes to earth.
In one instance a British scientist
became almost convinced that he
had captured some specimens of real
cosmic dust. 1t was shown, however,
that the specimens were obtained
near a furnace, and the smoothness
and shape of the interesting sam
Piles proved due to heat from the
fire.
But If the cosmic dust is proving
elusive, the dust count at least goes
forward with dispatch. Dust has
been counted by different devices
for a number of years, but never so
Systematically nor exhaustively as
in the present experiment.
The instrument employed consists
of three essential parts: a dampen-
ing chamber in which moisture con-
denses on each particle; a small box
at lllt liz VI liiC ClldllibCI 1Ollldlli-
ing a narrow slit; and an air pump
which produces a partial Yacuum
back of the slit, so that a measured
quantity of air with the moisture
coated dust particles flows rapidly
through the slit, strikes a small
glass disk in front of it, and there
the dust particles stick.
With a high powered microscope,
tho GAinnf1Cf fhan nnVnfG tho rJIY11-
Der of particles on the glass disk
and makes his estimate as to the
number in each cubic centimeter of
air. The microscope magnifies the
| grains by 1000 diameters, or a mil
lion times in area. Dust grains sew
Observation-Disclosures of an inch in
diameter are the smallest that the
microscope reveals. Other methods
OF investigation prove that particles
smaller than this are many times
more numerous than those that can
be counted with the microscope.
Investigations show that cities
vary greatly as to business. In COM
paratively dust-free regions there
may be only a hundred or so par
ticles to a cubic centimeter of air,
! according to microscope count, while
in factory districts or in the down
town section of a smoky city there
may be as many as 1000 or ever
10000 on an ordinarily clear day
If o include the particles that are
too fine to be thus, counted, the num-
Der lurking in a room or street may
run into the millions Scientists have
set the figure of dust particles per
cubic centimeter in a dusty room
as high as IS, 600, 1000.
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In cities that burn soft coal and