Plant oils matter: agricultural soap

Soap properties were discovered 3,000 years ago by the Romans. Animal fat had dripped down into the ashes of a cooking fire and that mixture dripped into a river where clothes were washed. People noticed that this fatty-ashy mixture cleaned clothes better than plain water. The science in this story is that the animal fat contained fatty acids and glycerine (triglycerides). The ashes contained a type of salt (a base known as alkali). When combined, the triglycerides and alkalis made soap. Today, the long names on the list of ingredients on a soap package, like “sodium stearate,” or “sodium palmitate,” are the names of the specific fatty acids present.