The following is the results of your search for fuller's soap.
Fuller's soap: (Heb. borith mekabbeshim, i.e., "alkali of those treading cloth").
Mention is made
(Proverbs 25:20; Jeremiah 2:22) of nitre and also
of soap (Heb. borith) used by the fuller in his operations. Nitre is
found in Syria, and vegetable alkali was obtained from the ashes of