Common salt (chemically sodium chloride) like other salts is soluble in water, so one of
the most abundant natural sources of salt is the ocean. One liter of sea- water contains
about 25 Grams of salts (of which some 18 grams is sodium chloride).
17th century Irish scientist, Robert Boyle, was the first to show that sea –water owed
its bitter taste to materials that were dissolved in it when the seas were made and from
land that had been eroded by rivers. In fact, the salts in the ocean are the result of over
two billion years of disintegration f rocks of the earth’s crust, and mostly those which
are volcanic in origin. Soluble materials –like salt remain in the sea –water while the
insoluble materials have formed ocean sediment and sedimentary rocks. To day, rivers
are still transporting dissolved salts to the ocean, and much of these have been eroded
from sedimentary rocks that have previously passed through the same cycle. It is
probable that the amount of salt in the ocean has changed little over millions of years.
What causes Hurricanes?
Hurricanes, which are known by a variety of names throughout the world, including
typhoon and cyclone, are essentially violent tropical storms associated with extremely
high winds. In fact, the technical definition of a hurricane is a cyclonic disturbance with
wind speeds above 120kmph. A cyclone is a region of low air pressure (sometimes
referred to as a depression) and they cause the major changes in our weather. In the
tropics, the latitudes nearest to the equator, cyclones are usually weak and the weather
generally predictable. How ever, this pattern can change dramatically if a cyclone from
outside this area enters the tropics and the result may be a hurricane. The energy for these
great disturbances comes from the heat of the tropical oceans, giving strong, spiral air
currents with high winds.
Hurricanes can cause great damage if they reach and, whipping up huge weaves along the
coast and causing server flooding in addition to the damage caused by the winds. One of
the most divesting ever known swept of an estimated 500,000 people.
The wale
Whales are animals, or warm –blooded animals. They are highly intelligent, even the
smallest members of the animal kingdom. The largest member of the whale family is
the blue whale, which weighs as much as twenty-five elephants and is the biggest living
mammal.
Whales need oxygen, just as we do. They come to the surface of the sea to fill and empty
their lungs. The stale air in the lungs is exhaled in a great spout of water. The whale
inhales again in two or three seconds. It then dives under the sea, where it can remain for
almost fifty minutes without breathing.
Can Dolphins talk?
Since ancient times, the dolphin has been considered a special animal. But it is only
recently that research has discovered that the friendly, playful dolphin is highly
intelligent. Some scientists consider the dolphin to be even more intelligent than
chimpanzee.
Dolphins and porpoises belong to the same family as whales. They are all animals. But
much more is known about the dolphin than the porpoise. Dolphins adapt readily to
capacity, while porpoises, when taken out of their natural environment, go into shock and
die. All the performing `porpoises’ in aquariums are really bottle-nosed dolphins, and can
be identified by their beak –like snouts.

Dolphins cannot talk in the same way as human beings do. But they do communicate
with each other through a series of noises that sound to us like whistles, squeaks, creeks,
chirps, and clicks. Dolphins also make some sounds that are beyond humans’ range of
hearing. They make all their sounds by blowing different amounts of air through their
blow holes.
Much research has been done on the dolphin’s language, and more is still going on.
People haven’t been able to learn the dolphins’ language. Dolphins learn commands
given in our language and even understand them. Some bottle –nosed dolphins can even
imitate human words.