Not the substance used in making gunpowder, but natron, a mineral alkali composed of several salts of soda. It effervesces with vinegar, Pr 25:28, and is still used in washing, Jer 2:22. Combined with oil, it makes a hard soap. It is found deposited in, or floating upon, certain lakes west of the Delta of Egypt.

(Pr 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").

(See FULLER.) Pr 25:20, "as vinegar upon nitre so is he that singeth songs to an heavy heart." To the feelings of the heavy at heart songs are as grating and irritative as acid poured on alkali. Nitre is carbonate of soda or potash; mixed with oil it was used as "soap" (borit): Jer 2:22.

The natron of the moderns, not what is now called nitre, which is saltpetre. As vinegar upon natron or alkali (which would effervesce and evaporate) so is the unsuitableness of singing mirthful songs to a heavy heart. Pr 25:20. It is a mineral alkali, and with oil is made into soap. Jer 2:22.

Nitre.

Mention of this substance is made in

Pr 25:20

"and as vinegar upon nitre"--and in

Jer 2:26

The article denoted is not that which we now understand by the term nitre i.e. nitrate of Potassa--"saltpetre" --but the nitrum of the Latins and the natron or native carbonate of soda of modern chemistry. Natron was and still is used by the Egyptians for washing linen. The value of soda in this respect is well known. This explains the passage in Jeremiah. Natron is found In great abundance in the well-known soda lakes of Egypt.

NITRE, ???, Pr 25:20; Jer 2:22. This is not the same that we call nitre, or salt-petre, but a native salt of a different kind, distinguished among naturalists by the name of natrum. The natrum of the ancients was an earthy alkaline salt. It was found in abundance separated from the water of the lake Natron in Egypt. It rises from the bottom of the lake to the top of the water, and is there condensed by the heat of the sun into the hard and dry form in which it is sold. This salt thus scummed off is the same in all respects with the Smyrna soap earth. Pliny, Matthiolus, and Agricola, have described it to us: Hippocrates, Galen, Dioscorides, and others, mention its uses. It is also found in great plenty in Sindy, a province in the inner part of Asia, and in many other parts of the east; and might be had in any quantities. The learned Michaelis plainly demonstrates, from the nature of the thing and the context, that this fossil and natural alkali must be that which the Hebrews called nether. Solomon must mean the same when he compares the effect which unseasonable mirth has upon a man in affliction to the action of vinegar upon nitre, Pr 25:20; for vinegar has no effect upon what we call nitre, but upon the alkali in question has a great effect, making it rise up in bubbles with much effervescence. It is of a soapy nature, and was used to take spots from clothes, and even from the face. Jeremiah alludes to this use of it, Jer 2:22.