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Hebrew: borith mekabbeshim, i.e., “alkali of those treading cloth”
Mention is made (Proverbs 25:20; Jeremiah 2:22) of nitre and also (Mal. 3:2) of soap (Hebrew: borith) used by the fuller in his operations.
Nitre is found in Syria, and vegetable alkali was obtained from the ashes of certain plants. (See SOAP.)