Easton's Bible Dictionary: M. G. Easton, M.A., D.D.

Fuller's soap

(Heb. borith mekabbeshim, i.e., "alkali of those treading cloth"). Mention is made (Pr. 25:20; Jer. 2:22) of nitre and also (Mal. 3:2) 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 certain plants.

Original from The Bible Foundation - bf.org. They claim public domain status for their original text.