Soap

(Jer. 2:22; Mal. 3:2; Heb. borith), properly a vegetable alkali, obtained from the ashes of certain plants, particularly the salsola kali (saltwort), which abounds on the shores of the Dead Sea and of the Mediterranean. It does not appear that the Hebrews were acquainted with what is now called “soap,” which is a compound of alkaline carbonates with oleaginous matter. The word “purely” in Isa. 1:25 (R.V., “throughly;” marg., “as with lye”) is lit. “as with bor.” This word means “clearness,” and hence also that which makes clear, or pure, alkali. “The ancients made use of alkali mingled with oil, instead of soap (Job 9:30), and also in smelting metals, to make them melt and flow more readily and purely” (Gesenius).

The Hebrew term borith is a general term for any substance of cleansing qualities. As, however, it appears in (Jeremiah 2:22) in contradistinction to nether , which undoubtedly means "natron" or mineral alkali, it is fair to infer that borith refers to vegetable alkali, or some kind of potash, which forms one of the usual ingredients in our soap. Numerous plants capable of yielding alkalies exist in Palestine and the surrounding countries; we may notice one named hubeibeh (the Salsola kali of botanists) found near the Dead Sea, the ashes of which are called el-kuli , from their strong alkaline properties.