Page:The New International Encyclopædia 1st ed. v. 18.djvu/374

* SODIUM. 320 SODOMA. invented in 1886 by Castner, and consists in re- ducing sodium liydioxide by an iron carbide pre- pared by adding finely divided iron to melted pitch and coking the mixture in large cylinders. The metal is distilled over into condensers and is ])uriiied by passing through linen under petro- leum at about 100° C. (212° F.). Sodium (symbol, Xa : atomic weight, 23.05) is a very soft" wliite metal possessing a silvery white "lustre when freshly cut. Its specific grav- ity is 9.85, and its melting point is 95.0° C. (204° F.). It is one of the best conductors of heat and electricity, and is one of the most electro-positive metals. Its vapor is colorless when seen in thin layers, but has a purple or violet tinge by transmitted light when seen in quantity. Sodium Inirns with a bright yellow ilame when licated in the air. When thrown into cold water it decomposes it, liberating hydrogen, but not with sufficient heat to ignite the latter, unless the temperature of the water is above 60° C. (140° F.). The metal readily takes up oxygen, and in consequence finds its chief use inthe preparation of aluminum, boron, mag- nesium, and silicon by reduction from the oxides. Sodium forms alloys with many metals, and the amalgam with mercury is employed in the ex- traction of gold. It combines with oxygen to form a monoxide (Xa.O) and a peroxide (Na,0.), of which the former may be obtained by heating sodium hydroxide with sodium, yield- ing a gray mass, which melts at a dull red heat ; while the latter, which is a white solid that deliquesces in the air, is formed by heating metallic sodium in oxygen. The salts of sodium are among the most im- portant of the commercial chemicals. Chief among them is soilium acetate, which is pre- pared by treating acetic acid or vinegar with sodium carbonate, filtering the solution and con- centrating to crystallization. Sodium arsenate is prepared by fusing arsenious acid, sodium car- bonate, and sodium nitrate, dissolving the result- ing mixture in hot water, filtering, and crystal- lizing. The colorless crystals thus obtained are oflicial in the pharmacopa?ia and are used in skin diseases and as a substitute for arsenic. Mixed with sugar this salt is frequently em- ployed as a poison for flies. Sodium hromide and sorlium iodide, which are prepared by decompos- ing, respectively, ferrous bi'omide and ferrous iodide with sodium carbonate, are white crystal- line compounds that find some use in medicine as nervous sedatives. Sodium carhonate, which is the soda of commerce, is a colorless crystalline odorless compoiuid with a strong alkaline taste, which is found native in many mineral waters and as efflorescences in the neighborhood of soda lakes. Sodium hiearhonate or 'acid' sodium car- bonate is made by passing a current of carbon dioxide through a strong solution of sodium carbonate vmtil it is saturated and then allowing the mixture to crystallize, yielding a colorless compound which finds extensive use in the manu- facture of baking powders and of artificial min- eral waters, and also in medicine as an antacid. Sodium, Jiiipophoxphite is prepared by treating calcium hypophosphite with sodium carbonate and rccrystallizing the resulting product from alcohol. ' It forms small colorless crystals that are deliquescent and finds some use in medicine as a restorer in exhausted conditions of the nerv- ous system, and as an ingredient in the syrup of hypophosphites. Sodium hyposulphite, or more correctlj- sodium thiosulphate, is prepared by decomposing soluble calcium thiosulphate with either sodium sulphate or sodium carbonate, resulting in the formation of a colorless crystal- line compound that is efflorescent in drj" air, and is used in photography as a solvent for the unal- tered silver chloride or bromide on the film, and in medicine as an alterative and resolvent. Sodi- um silicate is prepared commercially by fusing sodium carbonate with sand and a small quan- tity of charcoal in a reverberatory furnace and then dissolving by prolonged boiling in water. (See Water-Glass. ) Sodium sulphite is ob- tained by passing gaseous sulphur dioxide into a solution of sodium carbonate and eva])orating the mixture to drj'ness or crystallization, result- ing in a colorless, transparent, efflorescent com- pound that is used as a bleaching agent under the name of antichlore, in the manufacture of paper, for the purpose of removing the last traces of chlorine from the bleached pulp : it is also employed in medicine as an antiferment. See also Soda: Salt; Saltpetre; Glauber's Salt; etc. SODOM (Heb. Sed«m) and GOMOU'RAH (lleb. 'amoruli). Two ancient cities near the Dead Sea. almost invariably spoken of together in the Bible. With Admah. Zeboiim, and Bela or Zoar, they formed the five 'cities of the plain,' which on account of the wickedness of their inhabitants are said to have been destroyed by a rain of brimstone, perhaps also accompanied by an earthquake. Lot and his family were the only ones who escaped. His wife, however, for disobedience was turned into a pillar of salt (Gen. xix. 1-29; Deut. xxix. 2.3; Zeph. ii. 9: Isa. i. 9). Some scholars sa,v the cities were at the northern end of the Dead Sea. others at the Sdutliern end. Names like Jebel Usdum (Sodom) and Zoara or Zughar (Zoar), at the southern end, point to a tradition of the existence of the cities there. The biblical story of the destruc- tion of the cities is considered by many critics similar to tales found among Arabs (and other nations) regarding the sudden disappearance of places. Those who thus deny the literal truth- fulness of the narrative call attention to the weird character of the district around the Dead Sea. fatal to plant' and animal life, as naturally suggesting the thought of some catastrophe. See Lot, SODOM, Apple of, A name sometimes given to the fruit of Solanum sodomseum. Many im- satisfactory attempts have been made to deter- mine the source of the true apple of Sodom or mad apjde of the Dead Sea region mentioned by Strabo, Tacitus, and Josephus, and described as beautiful to the eye. but filling the mouth with bitter ashes if tasted. One explanation is that it is a kind of gall (q.v.) growing on dwarf oaks. These beautiful, rich, glossy, purplish- red galls are about 2 inches long and W2 inches in <liameter, and are filled with an intensely bitter, jiorous. and easily pulverized substance. SO'DOMA, II, properly Giovanni Antonio Bazzi (1477-1549). An Italian painter of the High Renaissance. He was born at Vercelli (Piedmont) and studied for six years with Mar- tino de Spanzattis, a painter on glass. He then came under the influence of Leonardo da Vinci, probably at Milan, and though he maintained an