BLEACH
(Heb. “Nether”).
It would be better to translate as “natron”, a carbonate of soda obtained from nature and used by the ancients (Prov. 25:20, translated here as “soap” in KJV).
Carbonate of soda was found in Asia Minor, in Syria, and especially in a valley of lakes with alkaline deposits in Lower Egypt, the Wadi eI-Natroun, about 100 km west of Cairo.
It was used to embalm Egyptian mummies.