Basics and Discovery of Atmospheric Chemicals - Air Pollution and Global Warming: History, Science, and Solutions - page 8

1.2.1.6. Sodium Carbonate (Solid)
Sodium carbonate [Na 2 CO 3 (s)] is a crystal mineral
first found by the Egyptians in the Lakes of Natron, a
group of six lakes to the west of the Nile Delta. The
Egyptians called it “nitrum.” Its name was modified
to “nator” by the Hebrews, “nitron” by the Greeks,
and “natrum” in the fifteenth century. Today, its min-
eral name is natrite .For centuries, it has been used as
an ingredient in soaps. Some chemical industry names
for it have been washing soda , soda ash , and salt
cake .The manufacture of sodium carbonate for use
in soaps resulted in acid deposition problems in Eng-
land and France in the nineteenth century (Chapter 10).
In the air, sodium carbonate is present in soil dust
particles.

Figure 1.5. Worker breaking sulfur inside volcanic
crater of Kawa Ijen, Indonesia. C Henri Faure/

Dreamstime.com.

1.2.1.7. Calcium Carbonate (Solid)
Calcium carbonate [CaCO 3 (s)] is a crystal present in
pure form in the minerals calcite and aragonite and in
mixed form in limestone, marble, chalk, and shells and
skeletons of invertebrates. Limestone is sedimentary
rock containing calcite or dolomite [CaMg(CO 3 ) 2 (s)],
marble is recrystallized limestone, and chalk (Figure
1.7) is fine-grained rock made of skeletons of microor-
ganisms. In the ancient world, chalk was used for writ-
ing. In the air, calcium carbonate is present in soil dust
particles. The name calcite originates from the word
“calcspar,” itself derived from the Greek word for lime-
stone, khalix .

1.2.1.5. Carbon
Elemental carbon ( carbo in Latin, meaning “charcoal”)
waswell known in the ancient world, although it is
unlikely that alchemists at the time knew that diamonds,
graphite (plumbago), and charcoal all contained carbon.
Carbon in diamonds and graphite is in pure crystalline
form. In charcoal, coal, and coke, it takes on a variety of
shapes and structures. In the ancient world, diamonds
were valued only for their rarity, not for their beauty,
because diamonds were not cut (and thus did not shine)
until the fifteenth century (Figure 1.6). Graphite was
used to make black marks on paper, and charcoal was
used as a fuel. Today, the emission of elemental carbon
(also called “black carbon”) in the form of soot particles
exacerbates global warming and visibility and causes
health problems.

Figure 1.7. Calcite rock formations in form of a
mushroom and a chicken in White Desert of Egypt.
C

Figure 1.6. Uncut diamond stones embedded in soil
within a mine. C Kheng Ho Toh/Dreamstime.com. Time De Boeck/Dreamstime.com.