BACKGROUND:
Salt is an important resource in the United States and
other nations. It is used every day in many aspects of our lives, from
manufacturing to water purification. It is also an essential ingredient for
maintaining a fluid balance in our bodies.
Salt crystallizes in a cubic pattern, and usually has
a cubic appearance in hand specimens. The melting point of salt is 800E C. It
dissolves easily in cold water and a little more readily in hot water.
Common salt, when mixed with ice, lowers the melting point of the ice,
making it melt. Salt is thus used on ice covered streets, so people or cars
will not slip.
Common salt is also used in many manufacturing
processes. It is employed as a preservative or seasoning in food processing,
for curing hides, and as a brine for refrigeration. It is used to make
sodium carbonate (washing soda), sodium bicarbonate (baking soda), sodium
hydroxide (caustic soda), hydrochloric acid, bleaching powder, and many
other chemicals. It is also used as a flux in metallurgical processes. It is
also an important ingredient in the manufacture of cement.
Salt, often said to be worth its weight in gold, has
played a vital role in nearly every civilization since the beginning of
time. It has served to preserve and improve the taste of food, as money, and
as a spiritual icon. Some examples are listed below:
- Ancient Greeks exchanged their slaves for salt
- Romans paid their soldiers partly in salt
- Chinese, in 2700 BC, wrote of 40 different kinds of
salt
- The French Revolution was sparked, in part, by a
salt tax
- Ancient Ethiopians used salt disks as a form of
currency
- In the United States, the Erie Canal was built
largely to transport salt
- In Slavic countries, salt is given to a bride and
groom to symbolize health and happiness
- Many of Napoleon's troops died during retreat from
Moscow due to a lack of salt
- The English increased their use of salt during
Queen Elizabeth's reign when she required her subjects to eat fish on
Wednesday and Friday
PROCEDURE:
- Show the Salt Institute video (can be purchased from The Salt
Institute website listed below). This presentation shows that salt is
essential for life. It will take students to far away places and trace
the historical importance of salt. It explores the collection and
packaging of salt, as well as its various forms and uses throughout the
United States, (including the "mining" and harvesting
technology used in the San Francisco Bay area.)
- Have the students write a paragraph on the importance of salt. They
can find information in the library or search the internet.
