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Article: Soap: How Can Something Made From Grease Get You Clean?
- Article from:
- The Washington Post
- Article date:
- January 11, 1995
CopyrightThis material is published under license from the Washington Post. All inquiries regarding rights should be directed to the Washington Post. (Hide copyright information)
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At least 3,000 years ago somebody figured out that if you mix
ashes and grease, you can make not just really messy gunk but
something that seems almost the opposite. Mix the two under the right
conditions, as the ancient Romans and Phoenicians learned to do, and
you get soap.
Chemically speaking, you get a molecule with two parts -- a head
and a tail. The head is an alkali such as the potash that is abundant
in wood ash. The tail is a long, dangling chain of atoms called a
fatty acid.
A typical fat molecule, such as those discussed in the New Tech
piece (next door), is made of three fatty acid chains attached at one
point. (See triglyceride model in photo.) In making soap, the chains ...