The morning news. [volume] (Savannah, Ga.) 1887-1900, 1891-12-27
CURIOUS THINGS ABOUT DUST.
Without It There Would Be no Rair
or snow or Hail

without II There Would Be no Rain
or snow or Hail
From the Chicago tribune.
A highly interesting article on ''Dust" by
J. g. Mcpherson describes the discovery
made q few years ago by John Aitken OF
Falkirk. Scotland, in regard to the presence
and behavior OF dust particles in air and
water, and especially in the atmosphere
He fonnd that without such dust there
could be no rain, nothing but continuous
dew in moist climates. There would
be no need for umbrellas. but
also no means Of preventing the
skin and clothing from being constantly
wet. Invisible dust Is absolutely necessary
for the production of fog, cloud, mist, snow,
sieet, hail and rain, their fine particles act
ing each as a nucleus around which the
vApor in the air clusters to form q cloud
particle. By means OF al ingenious appa-
ratus these dust particles have been counted,
and found TO range from about 81. 900 900
down to only thirty-four in the cubic inch
in air. The greatest number was found
10 room after crowded meet
ing. and the least on the top
of Ben Nevis, which Is the highest
mountain In Scotland. This explodes the
old theory that the particles OF water vapor
have to combine with each other 10 form a
cloud particle. and perhaps may lead up to
ducing rain, unless that DO abandoned alto
gether. 1t leads up to the idea that grant
ing Il sufflciency of moisture In the air it
may be made to condense by seattle ring
among it q large number Of dust particles,
each OF which will attract around i5 the ma
terial part Of cloud. that being the first
step in the process Of producing rain. Tor
which a mere defamation, however great, is
neffectual.
Mr.. Aitken has also shown that the Drills
fancy and variety Of the coloring often OBJ
served at sunset are due to suspended dust
in the atmosphere. He argues that in the
upper air there must always be dust, for
without it no clouds could be formed to
shield US from the suns scorcbing rays, and
Of cosmic dust there must be q considerable
quantity suspended in the cir, which 10 pro-
duced by the waste from the millions of
meteors that daily fall into 1t. The ire
mendous eruptions at Krakaroa, in
the straits OF Sunda. are computed
to have thrown up no less than
10000 cubic yards of dust which
actually fell around the volcano, while the
decks of vessels hundreds Of miles away
were covered with 1t. Much OF this dust
remained In the air for several years, and
gave the brilliant sunsets 70 often described.
If our atmosphere we're perfectly devoid of
dust tho SUMS light would simply pass
through without being seen, and total dark
ness would ensue soon after the sun dipped
below the horizon. The length of our
twilight, therefore, depends upon the
amount of dust in the atmosphere. And
this leads up to thought not stated in the
article Ii Is that the arg 1ment adduced
to prove that the mooas atmosphere 10 not
sufficient to balance more than tie thirtieth
part of an inch Of mercury in the barome-
ter may be a bad one. IL amuch larger
quantity of air than that were free from
dust particles there would be an absence Of
the refraction which has hitherto been
supposed inseparable from an aerial en-
velope. Hence the moon may have more
air surrounding her than she has hitherto
been credited with, but there would be no
opportunity for the snowfall which some
have fancied to occur recently on our sateI-
lite.
The sources Of the dust In our atmosphere
are numerous, in addition to those previ-
ously mentioned. On and near the sea the
air is tmpregnated with brine dust. But
burned sulphur is the most active of all
substances as a fog-producer il tue cities.
No less than $50 tons of the products Of the
combustion of sulphur from the coal used
are thrown into the atmosphere Of London
every day in winter. But the power
ful deodorizing ana antiseptic prop
critics OF the sulphur assist In
sanitation, and the writer hints that II may
be better TO bear the Inconvenience of fogs
than be subjected to the evils of a pesti-
leucs. This srooke can, howevar, be dissi-
pated by electric discharges, and the air is
in this way cleared by lightning. The or
ganic germs that float In the air are also
causes of diseases. as well as filth, but they
are less harmful thaA they would be il not
repealed from the lung surface OF the
healthy human being who breathes air conf
tanning them.