One end of the soap molecule is attracted to oil and keeps away water, while the other end attaches itself to water and repels oil. This special quality of the soap molecule allows it to suspend oils, which attract dirt. Water can then wash away the soap and the dirt.
FAITH LAPIDUS: No one knows exactly when humans first developed soap. Archeologists have found containers filled with a material similar to soap while studying the ancient cultures of Babylon and Egypt.
One story says that soap got its name from Mount Sapo, a place where ancient Romans used to sacrifice animals to their gods. Rainwater washed melted animal fat and wood ashes down the mountain into a river where women were washing clothes. The women found that the ashes and fat combination made their clothes much cleaner. The story may not be true. But it is likely that the discovery of how to make soap may have been accidental.
STEVE EMBER: Soap businesses began to appear in England, France, and Italy during the Middle Ages. By the twelfth century, soap- making centers had developed in cities such as Marseilles, France and Savona, Italy. Later, Bristol, England also became an important city for soap production. Two scientists helped modernize soap production. The French chemist Nicolas Leblanc discovered how to make soda ash from salt in the late eighteenth century. As a result, soda, a main material in soap, became easier to make.
But this process also released large amounts of deadly hydrochloric acid gas. The Belgian chemist Ernest Solvay later developed a better method of soda ash production in the eighteen sixties.
最新
2013-11-25
2013-11-25
2013-11-25
2013-11-25
2013-11-25
2013-11-25