killing the fish and other organisms that
live in them. Acid rain also damages
various kinds of vegetation, including
farm crops and trees. In addition, acid
rain corrodes, or wears away, surfaces of
buildings and other structures.
By the early 1990s tens of thousands of
lakes had been destroyed by acid rain.
The problem has been most severe in
Norway, Sweden, and Canada. Damage
from acid rain is not limited to the
countries that produce the pollution.
This is because winds carry the pollution
around the globe.
Despite much discussion between many
countries, there is still no clear solution
to the problem. The chief reason is that
it is expensive to control the pollution.
However, since the damage from acid
rain to the environment is permanent,
the environmental costs are greater.
Acne
Most teenagers and some adults experience
a skin condition called acne. Some
cases of acne are very mild and go away
without leaving any signs. Others are
more serious and may cause scarring.
Boys are more likely than girls to have
severe acne.
Lesions (abnormal bumps or spots) on
the skin are the main symptom of acne.
Acne lesions are commonly known as
pimples. They occur especially on the
face and neck.
Acne is caused by changes inside the
body that affect the skin. These changes
occur naturally as a boy or girl reaches
puberty, or matures. At that time the
body produces more of chemicals called
Acid rain can be very damaging to trees
and other plants. The branch on the left has
been affected by acid rain. It looks much
different than the branch on the right.
18 Acid Rain BRITANNICA STUDENT ENCYCLOPEDIA
hormones. Some of those hormones
speed up the skins production of oil.
The extra oil clumps together with dead
skin cells to clog pores, or tiny openings
in the skin. As the oil gland under a
clogged pore makes more oil, the pore
swells up to form a pimple.
There is very little a person can do to
prevent acne. However, there are treatments
for clearing up acne and ways of
preventing acne from getting worse.
Washing the skin twice a day with a
mild soap can be helpful. This removes
some oil and dead skin cells that help to
clog skin pores.
In some cases a doctor may prescribe
medicine to treat infections caused by
acne. Doctors may also suggest medicated
lotions or creams that can be put
on the skin.
#More to explore
Hormone Skin
Acropolis
Ancient cities were often built around a
fortress on top of a hill. When a city
spread to the area below, the high part
came to be called the acropolis, which
means city at the top in Greek. The
best-known acropolis is in Athens,
Greece.
The buildings of the Athens Acropolis
were made mostly of white marble. Parts
of some of the buildings, including a
temple called the Erechtheum, are still
standing today. The Erechtheum had a
porch with marble columns in the shape
of female figures.
The most famous surviving building is
the Parthenon. The Parthenon was built
almost 2,500 years ago and was dedicated
to the goddess Athena. Athens was
later ruled by Christians who made the
Bumps called pimples are the main sign of
acne.
The ruins of the Parthenon stand out on the
Acropolis in Athens, Greece.
BRITANNICA STUDENT ENCYCLOPEDIA Acropolis 19
Parthenon a church. In the 1400s Turkish
forces took control of the Acropolis
and made the Parthenon an Islamic
mosque. In 1687, during a war, some
gunpowder stored there exploded,
destroying the middle of the building.
In 1801 a British diplomat named Lord
Elgin took many sculptures and carved
panels from the Parthenon and brought
them to England. They were put on
display at the British Museum. The
Greek government, however, asked for
their return to Greece. The sculptures
remained on display while the dispute
continued into the 21st century.
#More to explore
Athena Athens
Acupuncture
Acupuncture is an ancient Chinese form
of healing. It involves piercing the skin
with thin needles to relieve pain. Today
acupuncture is also popular in Europe,
the Americas, and Australia.
Modern doctors accept that acupuncture
can control pain and nausea. Some doctors
recommend acupuncture along with
regular medical treatments for such ailments
as asthma, high blood pressure,
indigestion, and stress. Doctors in China
have even used acupuncture instead of
drugs to stop pain during surgery.
People who practice acupuncture must
take courses to learn how to do it correctly.
In many places only medical doctors
may perform acupuncture.
During treatment the patient lies on a
table while the acupuncturist sticks special
needles into certain points on the
body. The needles are made of metal and
are about as thick as a human hair. They
normally go less than 0.5 inch (1 centimeter)
into the skin. There are hundreds
of possible points where the needles can
be stuck, each with a different effect.
Doctors are not sure how acupuncture
works. Some think that the needles
cause the body to produce pain-killing
chemicals. Others think that the needles
block pain signals from traveling along
the nerves to the brain. Some think that
acupuncture acts like a placeboa treatment
that works only because patients
believe it will.
Adams, Abigail
Abigail Adams was the wife of President
John Adams and the mother of Presi-
A woman receives an acupuncture
treatment.
20 Acupuncture BRITANNICA STUDENT ENCYCLOPEDIA
dent John Quincy Adams. Her reading
and her family life gave her a good
understanding of politics. She strongly
favored American independence and
universal liberty. She was also determined
to overcome the limits that were
placed on women at the time.
Abigail Smith was born on November
22, 1744, inWeymouth, Massachusetts.
As a girl she studied the books in her
fathers large library.Women could not
go to college then, but Abigail received a
good education at home.
In 1759 Abigail met the young lawyer
John Adams. They shared interests in
reading, writing, and politics. They married
in 1764 and settled on a farm in
Braintree (now Quincy), Massachusetts.
They had five children. Abigail, John
Quincy, Charles, and Thomas survived
to adulthood.
John Adams law practice and political
duties kept him away from home much
of the time. Abigail Adams stayed in
touch with her husband and other
family members by letter. Her letters
are full of her opinions on the
important issues of the day. This was
during the time when the American
colonies began to fight for
independence from Great Britain. She
wrote in favor of American
independence. Like her husband, she
also believed that slavery had no place
in a country dedicated to freedom.
In 1789 John Adams became the first vice
president of the United States. Eight years
later he became the second president.
Even during those terms Abigail was
often inMassachusetts running the
family farm. In 1800, however, she
moved with the president into the White
House, which was unfinished at the time.
After Adams term as president he and
Abigail returned to Quincy and settled
comfortably into retirement. Abigail