554 



SODA WATER 



SODIUM 



continued until fusion takes place. The ammonia 

 is recovered from the liquid filtered from the bicar- 

 bonate of soda by heating it with lime. After the 

 ammonia U driven off by neat the remaining liquid 

 u calcium chloride, which U generally run to 

 waste. 



See Lunge Treatise on the Manufarturr of Sulphurie 

 And and Alkali (1880); Diagram, with Key of the 

 LebUno Soda Prooeu, by J. J. Miller, 1891 (for itudenU) ; 

 Journal of Ckemical Induttry (vol. for 1888), containing 

 paper by Mr Chance on Sulphur Recovery. 



Soda Water. See AERATED WATERS. 

 Suderharan, a seaport of Sweden, on a bay of 



the i tulf of Bothnia, 13 miles N. of Gene, exports 

 some 250,000 tons of iron and timber (in 600 vessels) 

 annually. It has been frequently burned down, the 

 last time in 1865. I'op. 9044. 



Sodium (syra. Na ; eqniv. 22^29 ;sp. grav. 0-973) 

 is one of the metals of the alkalies, its oxide being 

 soda. Its properties closely resemble those of the 

 allied metal potassium. It is of a bluish-white 

 colour, is somewhat more volatile than potassium, 

 and further differs from that metal in having a 

 higher fusing-point about 208 (97 C.), a greater 

 specific gravity, and in not catching fire when 

 dropped in water (unless the water is heated), 

 although, like potassium under similar conditions, 

 it partially decomposes it and liberates hydrogen, 

 and at tlie same time communicates a strong 

 alkaline reaction to the solution. If, however, 

 a piece of unsized paper is placed on the sur- 

 face of cold water, and the sodium is placed on 

 the paper, the metal takes fire and burns with 

 a deep yellow (lame. Strictly speaking, it is the 

 liberated hydrogen rather than the metal which 

 burns ; but a little sodium, volatilised by the 

 heat, burns with the hydrogen. When heated 

 in the air it burns with its characteristic yellow 

 flame, and is converted into soda. When ex- 

 posed in vacua to a red heat it assumes the 

 form of vapour, and admits of distillation. Like 

 potassium, it must lie kept immersed in naphtha, 

 o as to exclude the oxidising action of the 

 air. As a reducing agent it is little inferior to 

 potassium ; and as its combining power is lower, 

 and it is obtained much more cheaply, it may 

 Usually be advantageously substituted for potas- 

 sium in reducing operations. Sodium does not 

 occur in the metallic form in nature, but its com- 

 pounds are very widely distributed. It is found by 

 tar the most abundantly in the form of chloride of 

 sodium (or common salt), but it likewise occurs as 

 alliite or soda-felspar, cryolite (the double fluoride 

 of sodium and aluminium!, lx>rax (the biborate of 

 soda), trona (the sesquicarbonate of soda), and 

 Chili saltpetre (nitrate of soda). Duhaniel in 1736 

 discovered that potash and soda ( now known to be 

 tli<' oxides Hi potassium and sodium) were distinct 

 1 todies. Sir H. Davy first obtained the metal 

 Sodiu-n in 1807. The symbol of this metal, Na, 

 U the abbreviation of Natrium, which U derived 

 from \ntro. , one of the old names of native car- 

 bonate of soda. 



The methods of obtaining sodium are similar to 

 those already described for obtaining potassium. 

 Intimately mix 30 parts of common soda-ash with 

 13 parts of smajl joal and 3 parts of chalk, knead 

 tin-in into a Mill' paste witli oil, heat tlirm in a 

 cove-'d iron pot till the oil is decomposed, and 

 finally distil them in an iron retort with the pre- 

 cautions which are noticed in describing the pre- 

 paration of potassium. The object of adding the 

 chalk is to prevent the separation of the char- 

 coal from the carlmnate of soda when the latter 



fuses. This mixtun ^lil to yield nearly one- 



evpnth of its weight of sodium. 



Sodium combines with all the elementary gaseous 



bodies, and two of these combinations, those w ith 

 oxygen and chlorine, are of extreme importance 

 and value. With oxygen sodium forms two coin 

 pounds an oxide, ba,U, and a peroxide, No./).. 

 The latter is of no practical value. The oxide 

 (soda) was formerly known as fossil or mineral 

 alkali, to distinguish it from ]x>tosh, which, fium 

 the source from which it was procured, was termed 

 vegetable alkali. Anhydrous soda, Na,O, is pro- 

 cured by burning the metal in dry air ; it is of a 

 yellowish-white colour, powciiully attracts mois- 

 ture, and retains the water so firmly that it cannot 

 be expelled by heat. Hydrated or caustic soda, 

 NaHO, closely resembles, both in it* properties 

 and in the mode of procuring it, the corresponding 

 potash compound. It is, however, not so fusible 

 as the latter, and is gradually converted, by ex- 

 posure to the air, into carbonate of soda, which is 

 also an infusible salt in its anhydrous state. Solu- 

 tion of hydrate of soda (or soda lye) is largely em- 

 ployed in the arts. It is prepared by lioiling a 

 tolerably strong solution of carbonate of soda in 

 milk of lime until a portion of the filtrate ceases to 

 effervesce on the addition of an acid. The solid 

 hydrate has a specific gravity of 2 - 13, and the 

 quantity of anhydrous soda in any solution may 

 be closely approximated to by determining the 

 specific gravity of the fluid and referring to a table 

 indicating the strength corresponding to the specific 

 gravity. 



Many of the combinations of the oxide of sodium 

 (soda) with acids constituting soda-salts are of 

 great importance. Carbonic acid forms three salts 

 with soda a normal carbonate, a sesquicarbonate, 

 and a bicarbonate of soda. 



Carbonate of Soda, Na 2 COj, + 10H a O, the Soda 

 of commerce, is a colourless, inodorous salt, with a 

 nauseous alkaline taste. It crystallises in large 

 transparent rhomboidal prisms, which contain 

 nearly 63 per cent, of water, but it readily parts 

 with' all this water on the application of neat. 

 The crystals also lose the greater part of their 

 water on mere exposure to the air, when they 

 effloresce, and fall to powder. Water at 60 (15 

 C. ) dissolves half its weight of the crystals, and 

 iMiiling water considerably more, the solution act- 

 ing like an alkali on vegetable colours. This salt, 

 the natron of commerce, occurs native in the 

 natron-lakes of Hungary, Armenia, Ac. . in associa- 

 tion with sulphate of soda and chloride of sodium. 

 In other regions it appears in an efflorescent form 

 on the surface of the earth. It is now, however, 

 almost entirely manufactured from sea-salt. For 

 its manufacture, sec SUHA. 



Sesquicarbonate of Soda, Na,CO. + 2NaHCO $ + 

 ."!!._.( i. occurs native in the form of large, hard, non- 

 efliorescent prisms, in Hungary, Egypt, Mexico, 

 &c., under the name of Trtnm. \\ 'hen strongly 

 heated it loses one- third of its carbonic acid, and 

 becomes converted into the preceding salt. 



Bicarbonate of Soda, NaHCOj, may l>e formed 

 by passing a current of carliomc acid through a 

 strong solution of carbonate of soda, till saturation 

 takes place, and allowing the mixture to crystallise; 

 or it may be produced on a large scale by exposing 

 crystals of carbonate of soda to H prolonged current 

 of carbonic acid. Most of the bicarbonate in com- 

 merce is now, however, prepared by the ammonia- 

 soda process (see SODA), lu this a current of car- 

 liiuiic acid gas is passed through a solution of salt 

 in aqueous ammonia, when chloride of ammonium 

 and tiicarlionate of soda are produced. The birar- 

 I'lin.-ite crystallises in four-sided prisms, which 

 require 10 parts of water at an ordinary tempera- 

 ture for their solution. This salt is used largely 

 in medicine. See AKIt.VI 1 1 ' \\ \ I 1 I:-. 



Sulphuric acid forms with soda a normal and 

 an acid sulphate. The normal Suljihtite of Soda, 



