They're all rumored to use Dr. Bronner's ... in soap. It's mixed with an alkali, which is sodium hydroxide for bar soaps and potassium hydroxide for liquids. In this case, let's do liquid soaps.

Born in 1908 to a Jewish family that had been making soap since 1858, Emanuel Bronner was the third generation certified as a master soapmaker under the guild system of the time. In 1929, he brought ...