It is not applied to any use, and, being decomposed by water, it does not form salts with acids.
Cklorise and sodium form oaly one compound, the important one, common salt, formerly called muriate of sods, and now chloride of sodium (Noel). Of all natural soluble saltsthis occurs in the greatest quantity. It is met with solid, constituting rod. salt, in solution in salt springs and in the ocean, and In small quantity in almost all spring and river water. [Satv-TRADE; SODIUM. in NAT. HIST. Div.] This salt may be obtained artificially, either by the direct action of chlorine gas on sodium, or by saturating hydrochloric acid with soda; by evaporating the solution, common salt is obtained, which, in what ever manner or from whatever source procured, has, when pure, the following properties :—it is colourless, inodorous, has a purely Blaine taste unmixed with bitterness ; is transparent, brittle, and easily reduced to powder ; its specific gravity is about ; when exposed to moist air, it deliquesces; it crystallises in cubes, which form under common circumstances is but little subject to modification. It is almost as soluble in cold water as in boiling. Water at 32° dissolves more than at 60' ' • 100 parts of water at 58' dissolve 36 of salt, and in a boiling saturated solution, the temperature of which is 100 parts of water hold 4P2 of salt in solution. A saturated boiling solu tion does not deposit crystals on cooling, evaporation being necessary to produce this effect ; in pure alcohol it is insoluble. At a red heat common salt fuses, and on cooling it becomes a transparent brittle mass ; the crystals contain no water of crystallisation, but decrepitate strongly when heated, owing to the expansion of mechanically inter posed water. At a bright red heat it sublimes in the air, end tinges flame of a blue colour.
The uses of this salt have been known from the earliest ages. It is employed not only in seasoning food, but in preserving meat from putrefaction. It is used occasionally as a manure. In chemical manu factures it is employed for preparing hydrochloric acid, sulphate and carbonate of soda, and several other salts, and in the preparation of soap.
Sodium combines with fluorine, bromine, iodine; sulphur, phos phorus, &c. ; the compounds which they form are unimportant, not being extensively applied to any useful purposes. Their formation is accomplished by methods similar to those employed in the preparation of the corresponding salts of POTASSIUM.
Salts of 0.ride of Sodium, or 0.risalts of Soda.
It is perhaps scarcely requisite to state that these salts are never prepared by directly acting upon the metal sodium, although for pur-_ poses of curiosity they might all of them be eo procured. The first which we shall notice is— /Citrate of Soda (NaO, salt may be prepared either by adding the metal, or soda, its oxide, to nitric acid • as a natural product it has, however, of late years been largely imported from Peru, where it forms a deposit similar to that of nitrate of potash in India. Nitrate of soda has a cooling saline taste, is inodorous and colourless; in a moist atmosphere it deliquesces; it readily crystallises, and the form of the crystal is an obtuse rhomboid • so obtuse indeed, and so near a cube, that the salt was originally called cubic nitre, to distinguish it from potash nitre, the crystals of which are prisznatip. According to Gay-Lussac, 100 parts of water at 32° dissolve 73 parts of this salt ; and at 212', 173 parts : water at 60° dissolves half its weight. It is sometimes found with crude nitrate of potash.
Like nitrate of potash, it deflagrates with charcoal ; but owing to its property of attracting moisture, it cannot be used in the manufacture of gunpowder. It is, however, used largely in making nitric acid, sulphuric acid, and as a manure.
There are three compounds of carbonic acid and soda; namely, 1, carkmate ; 2, sesqui-carbonate; and 3, bi-carbonate.
1. Carbonate of Soda (Na0, CO,+10 Aq.).—This salt, formerly called rulsearbonate of soda, was obtained from lumina or kelp: the former being the ashes of the Salsola soda, and prepared in Spain ; the latter the ashes of burnt sea-weed, manufactured in Scotland. Since the duty has been taken off common salt, carbonate of soda is prepared, for the numerous uses to which it is applied, by first converting common silt into sulphate of soda by means of sulphuric acid, and then treating the sulphate, or sall-cake, as it is called, with small-coal and chalk in a reverberatory furnace ; the result is a mixture of carbonate of soda sad oxyerulphide of calcium, termed Latbsodu, or black-ash, when this is treated with cold water, the oxysulphide remains undissolved, while the carbonate of soda is taken up by the water, and by evaporation to dryness yields what is called soda-ash.