The Lake Charles echo. [volume] (Lake Charles, Parish of Calcasieu, La.) 1876-1898, 1892-09-23
NO 8o
THs VALUE oF DUST.
Its Psrticles Form Free Surfaces for ths
ColIeetien Of Yapor.

Its Particles Form Free Surfaces for the
ColleetieR Of Yapor.
How can Invisible particles be brought
within the range Of onr vision? That
was one Of the first Of the mary marvel-
ous discoveries Of Mr.. John AStken, n,
r. S., Falkirk, q distinguished physiciat.
whose remarkable work has revolution
ized branch Of meteorology Ha
showed that without dust Ia The air
there could be no fogs, no mist, no cloud
and probably no rain. The PARTICLES cf
dust are the free surfaces, which, under
certain conditions, attract the water
yapor Of the atmosphere to form fog.
Invisible before, they become visible
when clothed all over with the moisture;
unseen as dust, they become distinct Is
fog particles.
This can be easily verified. Il oTdi-
nary air be forced through filter Of
cotton wool into glass receiver, " il
deprived Of an It's dust PARTICLES. Let
steam be introduced into this receiver
from boiler, no change will be OBJ
served; the vessel is quite transparent
But if q jet of steam be introduced into
a similar vessel containing ordinary air,
it will be seen rising in dense clo1di
then q beautiful fog will be formed 80
dense that it cannot be seen through. IN
the former case. when there was no
dust In suspension, the air remained
clear; in the latter case, when the ordi-
nary atmospheric dust was in The yes-
sci, fog at once appeared The invisible
dust then is detected BY the introduc-
tion Of water vapor,
Until very lately it was thought that
particles of water vapor combined with
each other to form cloud particle, but
it Is now found that some solid body,
however small, is required for this
formation In fact, when there are no
dust PARTICLES on which the water yapor
at a proper temperature and pressure
can condense, there ID at present no
knowledge as to the point AZ which the
change viii take place, But the 9ne
particles Of dust in the air act as FREQ
surfaces ON which the water vapor con-
denses into fog, When there is abuRd-
ance of dust in the air and little water
vapor present there is an oyerpropor-
tion of dust particles, and the fog par
tieles are IN consequence closely packed,
but light in form and small in size, and
take the lighter appearance Of fog. Ao-
cordingly, If the dust ID increased ia the
air, there is 4 proportionate increase ef
fog.
But ON the other hand il the dust
PARTICLES are fewer in proportion to the
number OF molecules Of water vapor,
each particle soon gets weighted, springs
into visible existence as If by creative
hand, and falls in mist or ram. II the
water vapm had no dust at all on which
to settle, it would use the objects ON the
surface of the ground for tine same end
as the grass, leaves, tree branches oI
house projections. Moiaturewould then
be ever dripping, The occasional genial
rain, though at times lashed up TO q
biting storm of sleet, would require to
give place to q constant wetness on the
roads and grass,
Umbrellas would not be needed, but
india rubber protectors for the feet and
legs would be in constant requisition,
Even the irritable housekeeper, ever an
noyed at the unaoeountahle appearance
Of dust in rooms which she left for clean,
weuld prefer the old necessary evil ia
this dry dust form than see the walls
dripping and the floor wet, Good
Words,