The Cambria freeman. [volume] (Ebensburg, Pa.) 1867-1938, 1885-01-09
INTERESTING FACTS ABOUT AIR.

There is always wind at the burn
ing of a building. because the heated
air rises and the cold air rnshes in TO
take its place.
Sound depends on the presence of air,
because the air is put in motion by the
action Of the body producing the sound,
in the same way as pool of water is
disturbed by throwing in "A stone. The
vibrations of the air gradually extend
themselves uRtil they reach the ear, and
communicate the idea Of sound to the
mind.
This is easily illustrated by clasping
a small bell with the hand. so as to stop
the vibration, when the sound will in
stantly cease or if a bell be placed un-
der an air pump, as the air is gradually
exhausted, the sound will grow fainter
and finally cease altogether.
All solid bodies conduct sound more
readily than the air, and generally their
conducting power is in proportion to
density, iron conducting ten and a-half
times better than the air.
Smooth, calm water is a very good
conductor, and even the earth conducts
sound much better than the atmosphere.
Hence the Indians, by laying their heads
on the ground, will discover the ap-
proach Of game or the march of a body
OF men, when others in the same situa-
tiOn would hear nothing.
But it is it's agency in respiration that
renders the study OF the air most impor-
tant. In ordinary cases the lungs are
filled with air about twenty times a min
ute, frOm zen to fifteen cubic inches be-
ing inspired each time, according to the
size of the individual.
Thus every full grown person re-
quires from twenty-five to thirty hogs
heads OF air daily, more than one hogs
head an hour. Not only is this amount
withdrawn from the atmosphere, but an
equal quantity of impure and poisOLous
gas is returned in its stead.
So there is a double source of contain
ination, to say nothing of the immense
amount of matter thrown off by the
skin.
The air thus received into the lungs
IS brought into contact with the whole
mass of the blood by cOntriyance so
wonderful as to merit more particular
description.
If TIE assertion that ''the undevout
astronomer is mad" he true, much
more must the undevout anatomist ue
liable to the same accusation for in
nothing is the wisdom and skill of the
Deity more manifest than in the struc-
ture of the human frame.
The lungs consist of a light porous
substance. penetrated in every part by
minute cells, separated from each 9th
er by \ membrane OF 50 peculiar A struc-
ture that Ee air readily passes through
u, while the blood is retained.
These cells are SO exceedingly minute
that cubic ilcn contains 1000. coo of
them and the whole lungs about 1SO,-
GOO, 600. wish a superficial surface Of 30
600 square inches, or nearly 40 square
feet, and all wrapped up i'm mass not
more than ten inches in length and five
or six inches in diameter.
These cells are divided into layers, 50
arranged that the cells of one layer are
filled with air, while those of the layer
next adjoining are occupied with blood.
the two sets being separated by a meU-
brane 50 porous that while tbs blood is
Tstained, the air can readily pass thro'
It.
By this means the whole mass OF the
blood is brought periodically in contact
with the air. The oxygen, amounting
tOOne-ffth OF the whole, combines with
the carbon of the blood aud is expelled
from the lungs in the form of ca1bonic
acid gas, while the nitrogen is returned
in pure state.-EUery Other Saturday.