The same as bor; vegetable lye (from its cleansing); used as a soap for washing, or a flux for metals -- X never so, purely.
see HEBREW bor
H1253. bor
I. בֹּר noun masculine lye, potash, alkali used in smelting metals Isaiah 1:25 **read probably כַּכֻּר as in a furnace (48:10); there seems no evidence that 'lye' (i.e. water mixed with the burnt ashes of plants containing potash, used formerly for washing) was ever used in refining gold or silver: compare J. NapierAnc. Workers in Metal {1856}, 15, 20, 25 WAM in SmithDB ii. 368; Amer. Rev. Ed. (1871, vol, iii), 1939. (see בֹּרִית).