Bible dictionaries
Nitre
What Bible dictionaries say about “Nitre”, one article after the other.
Easton’s Bible Dictionary & Webster’s 1828 Dictionary
Nitre - (Easton's Bible Dictionary)
(Prov. 25:20; R.V. marg., "soda"), properly "natron," a substance so called because, rising from the bottom of the Lake Natron in Egypt, it becomes dry and hard in the sun, and is the soda which effervesces when vinegar is poured on it. It is a carbonate of soda, not saltpetre, which the word generally denotes (Jer. 2:22; R.V. "lye").
Matthew George Easton, Easton’s Bible Dictionary; Noah Webster, American Dictionary of the English Language (1828)
The article in Easton + Webster 1828International Standard Bible Encyclopedia (ISBE 1915)
ni'-ter (nether; nitron): Nitre as used in the King James Version does not correspond to the present use of that term. Nitre or niter is now applied to sodium or potassium nitrate. The writer has in his collection a specimen of sodium carbonate, called in Arabic naTrun, which was taken from the extensive deposits in Lower Egypt where it is found as a deposit underneath a layer of common salt. Similar deposits are found in Syria and Asia Minor. This is probably the "nitre" of the Bible. the American Standard Revised Version has rendered niter "lye" in Jer 2:22, and "soda" in Pr 25:20. Soda or lye has been used as a cleansing agent from earliest times. It effervesces energetically, when treated with an acid; hence, the comparison in Pr 25:20 of the heavy-hearted man roiled by the sound of singing to the sizzling of soda on which vinegar has been poured.
See VINEGAR.
James A. Patch
International Standard Bible Encyclopedia — James Orr, general editor and contributors; CrossWire SWORD module ISBE 2.2
The article in ISBE 1915Smith’s Bible Dictionary
William Smith; revised by F. N. Peloubet and M. A. Peloubet; CrossWire SWORD module Smith 1.3
The article in Smith