THUNDER CLEARS THE AIR
The phrase "thunder clears the air" is familiar to all. It contains a very
vital truth, yet even scientific men did not know its full meaning until
just the other day. It came by experience to people who had been for ages
observing the weather; and it is one of the most pointed of the
"weather-lore" expressions. Folks got to know, by a sort of rule-of-thumb,
truths which scientifically they were unable to learn. And this is one.
Perhaps, therefore, we should respect a little more what is called
"folk-lore," or ordinary people's sayings. Experience has taught men many
wonderful things. In olden times they were keener natural observers. They
had few books, but they had plenty of time. They studied the habits of
animals and moods of nature, and they came wonderfully near to reaching
the full truth, though they could not give a reason for it. The
awe-inspiring in nature has especially riveted the attention of man.
And no appearance in nature joins more powerfully the elements of grandeur
and awe than a heavy thunder-storm. When, suddenly, from the breast of a
dark thunder-cloud a brilliant flash of light darts zigzag to the earth,
followed by a loud crackling noise which softens in the distance into
weaker volumes of sound, terror seizes the birds of the air and the cattle
in the field. The man who is born to rule the storm rejoices in the
powerful display; but kings have trembled at the sight.
Byron thus pictures a storm in the Alps:--
"Far along
From peak to peak, the rattling crags among
Leaps the live thunder! Not from one lone cloud,
But every mountain now hath found a tongue,
And Jura answers, through her misty shroud,
Back to the joyous Alps, who call to her aloud!"
Franklin found that lightning is just a kind of electricity. No one can
tell how it is produced; yet a flash has been photographed. When the flash
is from one cloud to another there is sheet-lightning, which is beautiful
but not dangerous; but, when the electricity passes from a cloud to the
earth in a forked form, it is very dangerous indeed. The flash is
instantaneous, but the sound of the thunder takes some time to travel.
Roughly speaking, the sound takes five seconds or six beats of the pulse
to the mile.
All are now taught at school that it is the oxygen in the air which is
necessary to keep us in life. If mice are put into a glass jar of pure
oxygen gas, they will at once dance with exhilarating joy. It occurred to
Sir Benjamin Richardson, some time ago, that it would be interesting to
continue some experiments with animals and oxygen. He put a number of mice
into a jar of pure oxygen for a time; they breathed in the gas, and
breathed out water-vapour and carbonic acid. After the mice had continued
this for some time, he removed them by an arrangement. By chemical means
he removed the water-vapour and carbonic acid from the mixed air in the
vessel. When a blown-out taper was inserted, it at once burst into flame,
showing that the remaining gas was oxygen.
Again, the mice were put into this vessel to breathe away. But, strange to
say, the animals soon became drowsy; the smartness of the oxygen was gone.
At last they died; there was nothing in the gas to keep them in life; yet,
by the ordinary chemical tests, it was still oxygen. It had repeatedly
passed through the lungs of the mice, and during this passage there had
been an action in the air-cells which absorbed the life-giving element of
the gas. It is oxygen, so far as chemistry is concerned, but it has no
life-giving power. It has been _devitalised_.
But the startling discovery still remains. Sir Benjamin had previously
fitted up the vessel with two short wires, opposite each other in the
sides--part outside and part inside. Two wires are fastened to the outside
knobs. These wires are attached to an electric machine, and a flash of
electricity is made to pass between the inner points of the vessel. The
wires are again removed; nothing strange is seen in the vessel. But, when
living mice are put into the vessel, they dance as joyfully as if pure
oxygen were in it. The oxygen in which the first mice died has now been
quite refreshed by the electricity. The bad air has been cleared and made
life-supporting by the electric discharge. It has been again vitalised.
Now, to apply this: before a thunder-storm, everything has been so still
for days that the oxygen in the air has been to some extent robbed of its
life-sustaining power. The air feels "close," a feeling of drowsiness
comes over all. But, after the air has been pierced by several flashes of
lightning, the life-force in the air is restored. Your spirits revive; you
feel restored; your breathing is far freer; your drowsiness is gone. Then
there is a burst of heavenly music from the exhilarated birds. Thus a
thunder-storm "clears the air."
After the passage of lightning through the air ozone is produced--the gas
that is produced after a flash of electricity. It is a kind of oxygen,
with fine exciting effects on the body. If, then, the life-sustaining
power of oxygen depends on a trace of ozone, and this is being made by
lightning's work, how pleased should we be at the occasional
thunder-storm!