What is…
“nitre” in the King James Bible?

also known as: niter

Hebrew: נֶתֶר —transliteration: nether

As he that taketh away a garment in cold weather, and as vinegar upon nitre, so is he that singeth songs to an heavy heart. —Proverbs 25:20 KJV

Various English word meanings have shifted over 400+ years. At the time of the King James Version translation of the Bible, its translation of the Hebrew word “nether” as “nitre” correctly reflected the 17th-century English usage and ancient understandings of the word nether.

The substance referred to differs from what “nitre” often means today: the mineral form of potassium nitrate (KNO₃), aka saltpeter, saltpetre; a soft, white, highly soluble mineral primarily found in arid climates or cave deposits. It has historical significance in the production of fertilizers and gunpowder.

The Hebrew word nether comes from a root implying “to release” or effervesce. It refers to a mineral alkali, specifically natron (sodium carbonate, Na₂CO₃, or washing soda) or a similar natural soda/lye. It is called “natron” 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 saltpeter.

Thus, modern translations of Proverbs 25:20 correctly say soda, not nitre.

Like one who takes away a garment in cold weather,
And like vinegar on soda, Is one who sings songs to a heavy heart. —Proverbs 25:20 NKJV

Like one who takes off a garment on a cold day, or like vinegar on soda,
Is he who sings songs to an aching heart. —Proverbs 25:20 NASB, LSB

Whoever sings songs to a heavy heart is like one who takes off a garment on a cold day, and like vinegar on soda. —Proverbs 25:20 ESV

This poetic proverb highlights the importance of emotional wisdom—well-intentioned but ill-timed comfort can aggravate pain, like mixing incompatible substances. The reaction with vinegar spoils the nether, perfectly suiting the proverb’s point about incompatibility.

Jeremiah

The Hebrew word נֶתֶר (nether / nēṯer, Strong's H5427) appears twice in the Old Testament: Proverbs 25:20 and Jeremiah 2:22. Modern translations render it as “lye,” “soda,” “natron,” or “alkali” for contemporary readers.

In Jeremiah the word refers to the property of nether as a strong alkaline cleansing agent, used figuratively for the futility of trying to wash away sin.