Nitre (נֶתֶר, ne'ther, from נָתִר, to tremble; Sept. ἀσύμφορον, Pr 25:20; νίτρον, Jer 2:22; Attic λίτρον, Plato, Tinceus, 60, D), a word occurring in Scripture only in the two places above referred to, where the substance in question is described as effervescing:with vinegar, and as being used in washing; neither of which particulars applies to what is now, by a misappropriation of this ancient name, called "'nitre," and which in modern usage means the saltpetre of commerce, but they both apply to the natr'on, or true nitrumn of the ancients. The similarity of the names which is observable in this case is regarded by Gesenius as of great weight in a production of the East, the name of which usually passed with the article itself into Greece. Both Greek and Roman writers describe natron by the words given in the Sept. and Vulg. Jerome, in his note on Pr 25:20, considers this to be the substance intended. Much has been written on the subject of the nitrum of the ancients; it will be enough to refer the reader to Beckmann, who. (Hist. of Inventions, 2:482, Bohn's ed.) has devoted a chapter to this subject, and to the authorities mentioned in the notes. It is uncertain at what time the English term nitre first came to be used for saltpetre, but our translators no doubt understood thereby the carbonate of soda, for nitre is so used by Holland in his translation of Pliny (31:10) in contradistinction to saltpetre, which he gives as the marginal explanation of aphronitrum. The word nether thus might be more properly rendered natron, a substance totally different from our nitre, i.e. nitrate of potash or" saltpetre." The original word nether is what is known among chemists as "carbonate of soda." It is found native in Syria and India, and appears there as the produce of the soil. In Tripoli it is found in crystalline incrustations of from one third to half an inch thick. Captains Irby and Mangles found lumps of this salt on the south-east shore of the Dead Sea. Natron, though found in many parts of the East, has ever been one of the distinguishing natural productions of Egypt. Hasselquist (Trav. p. 275) says that natrum is dug out of a pit or mine near Mantura, in Egypt, and is mixed with limestone, and is of a whitish brown color. The Egyptians used it (1) to put into bread instead of yeast, (2) instead of soap, and (3) as a cure for the toothache, being mixed with vinegar. Strabo and Pliny mention two lakes in the valley of the Nile, beyond memphis, where it was found in great abundance (Strabo, Geogr. [Oxf. 1807], xvii, p. 1139; Pliny, Hist. Vat. v. 9), and describe the natural and manufactured nitrum of Egypt (ib. 31:10). This substance, according to Herodotus, was used by the Egyptians in the process of embalming (2:76, 77). The principal natron lakes now found in Egypt, six in number, are situate in the barren valley of Bahr-bela- ma, "the Waterless Sea," about fifty miles west of Cairo, where it both floats as a whitish scum upon the water, and is found deposited at the bottom in a thick incrustation, after the water is evaporated by the heat of summer. It is a natural mineral alkali, composed of the carbonate, sulphate, and muriate of soda, derived from the soil of that region. Forskal says that it is known by the name of atrun or natrun, that it effervesces with vinegar, and is used as soap in washing linen, and by the bakers as yeast, and in cookery to assist in boiling meat, etc. (Flora Egyptiaco-Arabica [Hauniae, 1775], p. 45, 46; see Paulus, Sannmlung. v. 182 sq.). Combined with oil it makes a harder and firmer soap than the vegetable alkali. SEE SOAP. The application of the name nitre to saltpetre seems accounted for by the fact that the knowledge of natron, the true nitre, was lost for many centuries in England, till revived by the Hon. R. Boyle, who says he "had had some of it brought to him from Egypt" (Memoirs for a History of Mineral Waters [Lond. 1864-5], p. 86). See an interesting paper in which this is stated in the Philosophical Transactions, abridged, 1809, 13:216, etc.; and for a full description of the modern merchandise, uses, etc., of the natron of Egypt, see Sonini, Travels (Paris), vol. i, ch. xix; Andreossi, Memoire sur la Vallee des Lacs de Natron Decade Egyptienne, No. 4, vol. ii, p. 276, etc.;
Berthollet, Observations sur le Natron (ibid.), p. 310; Descript. de I'Egypte, 21:205; Beckmann. Beitrdge zur Geschichte der Erfindun en, 4:15 sq.; Michaelis, De Nitro Hebrceor. in Conmment. Societ. Regal. Praslect. 1:166; and Supplem. ad Lex. Hebraic. p. 1704; Shaw, Travels, 2d ed. p. 479; Gesenius, Thesaur. p. 930. SEE ALKALI.