SOD 



SODFORS, in Geography, a town of Sweden, in Weft 

 Bothnia; 1 8 miles N.W. of Umea. 



SODIA, a town of Arabia, in the province of Hedsjas ; 

 70 miles S.S.E. of Mecca.— Alfo, a mountain of Arabia, 

 in the province of Hedsjas ; 60 miles S. of Mecca. 



SODINUS, in Jncient Geography, a navigable river of 

 Afia, which runs into the Cophes, according to Pliny. 



SODIUM, in Chemi/ln, a fimple body and a metal. 

 This was difcovered by fir Humphrey Davy in the year 1807. 

 He had a few days before found that potafli was a compound 

 of a peculiar metal combined with oxygen, and he now found 

 that foda confided of a metallic fubftance combined with 

 oxygen. He firll produced it by expofing foda to the aftion 

 of the Galvanic battery. 



It is now obtained by fufiiig foda or muriate of foda with 



potafiium. The potaffium combines with the oxygen in the 



foda, and with the chlonne in the fait, leaving pure fodium. 



This metal is white, refembling filver ; and having the 



fame metallic lull re. 



Its fpecific gravity is between 9 and 10, water being I. 

 In the common temperature it is malleable. 



It allumes the liquid form at 200^ of Fahrenheit, and is 

 volatile at a red heat. 



If expofed to the air it would foon lofe its luftre, by com- 

 bining with oxygen, and in a little time would be converted 

 into foda. 



It is preferved in naphtha, like potaffium. 

 When heated in oxygen or chlorine, it burns with great 

 brilliancy. 



When thrown upon water, it does not fink but runs along 

 the furface, the motion being occafioned by the rapid efcape 

 of hydrogen gas, from its decompofing the water with 

 great rapidity. The floating mafs is feen to diminifh as it 

 runs along, till it difappears, when, as may be expefted, the 

 water is found to contain a folution of foda. 



Sodium, like other metals, is a conduftor of eleAricity. 

 Sodium combines with two dofes of oxygen. The one is 

 that which conftitutes foda ; the other is of an orange 

 colour, firft obferved by fir Humphrey Davy ; but for the 

 particulars of its nature we are indebted to M. M. Gay Luffac 

 and Thenard. 



Soda, in its pure ftate, is a folid of a greyi(h-white co- 

 lour, very hard, and breaks with a fmooth fraAure. In 

 iliis ftate it requires a ftrong heat for its fufion. When 

 expofed a little to the air, it abforbs water, afl'umes a whiter 

 colour, and becomes much more fufible by heat. Its vo- 

 latility is alfo increafed at the fame time. In this ftate, as is 

 the cafe with lime, potafh, and many of the metallic oxyds, 

 it is called an hydrate. 



The peroxyd of fodium is formed by burning fodium in 

 oxygen gas, an excefs of the gas being prefent. 



It is of a deep orange colour, and fufes at a much lefs 

 heat than foda. 



If thrown into water, one atom of oxygen efcapes in the 

 form of gas, leaving pure foda, which diftblves in the water. 

 This proves how clofely the excefs of oxygen is held. This, 

 however, is more confpicuoudy fiiewn in its aftion upon 

 combuftible bodies, with which it deflagrates. 



The atom of fodium has been confidered 22 ; hydrogen 

 being 1, and oxygen 7.5 ; hence the protoxyd would be 

 29.5, and the peroxyd 37. But from the experiments of 

 Gay LufTac and Thenard, it appears that the oxygen in the 

 foda is to that in the peroxyd as i to 1 1, or as 2 to 3 ; 

 but as the exiitence of half atoms would be abfurd, the 

 atom of fodium muft be confidered as equal to 44 ; the prot- 

 oxyd will then be 51.5 ; the deutoxyd, which is foda, will 



SOD 



be 44 +' 2 X 7.5 = 59, and the peroxyd 44 -f- 3 x 7.5 

 = 81.5. 



Soda combines with fulphur, and is called fulphuret of 

 foda. It poflefles properties differing but little from the 

 fulphuret of potafli. It is formed by fufing fulphate of 

 foda with common faw-duft. Like fulphuret of potalh, when 

 thrown into water, it firft diflblves, and decompofing that 

 fluid, the remaining fulphuret combines with the hydrogen 

 in its nafcent ftate to form hydrogen with fulphuret of 

 foda. This forms a greenifh-coloured fluid, having the 

 fmell of fulphuretted hydrogen. The phofphuret of 

 foda is alfo fimilar to the phofphuret of potafti. See 

 Potash. 



Sodium alfo combines with fulphur and phofphorus. 

 When fodium and fulphur are heated together in a veflel 

 filled with vapour of naphtha, they unite with all the figns 

 of fplendid combuftion, the fulphur fupplying the place of 

 oxygen . The compound is of a grey colour, producing ful- \ 

 phate of potafli by expofure to the air. Their proportions ' 

 ought to be 44 fodium to 15 fulphur for the firft, and 44 

 to 30 for the fecond fulphuret. 



Sodium has a fimilar effeft upon phofphorus, by which the 

 phofphuret of fodium is produced. It has no known aftion 

 upon carbon, azote, or hydrogen. 



Sodium combines with many of the metals, forming pe- 

 culiar alloys. With potaffium, in a fmall proportion, it forms 

 an alloy, which, agreeably to other alloys, is more fufible than 

 either of the metats. The alloy is of lefs fpecific gravity than 

 either of the metals, a circumftance not common with other , 

 metallic alloys. The latter faft goes to prove that there jj 

 is not a great affinity between the two metals. 



One part of fodium renders 40 of mercury fohd, at the 

 common temperature. When they combine, heat is difen- j 

 gaged. It aJfo combines with tin, without changing its 

 colour. When thefe alloys are expofed to the air, the 

 fodium is gradually feparated, by combining with the oxygen 

 of the atmofphere. 



Salts of Soda, or its Compounds tuith the yields. — Under this 

 head we ftiall comprife the muriate of foda, although, in 

 ftrift propriety, we might have been expefted to have treated 

 this compound under the aftion of fodium upon chlorine. 



Sulphate of Soda. — This fait is found native in moft fea- 

 vegetables : it has been called Glauber fait. It may be 

 eafily formed by adding fulphuric acid to the cryftallized 

 carbonate of foda, till the effervefcence ceafes, and the folu- 

 tion is neither acid nor alkaline. 



On evaporation and cooling, it eafily cryftallizes into fix- 

 fided prifms of a pearly appearance. Their tafte is cooling 

 and rather bitter. At the temperature of 60° it diflblves in 

 lefs than three times its own weight of water, and in much 

 lefs than its own weight of boiling water. When a folution 

 of this fait is concentrated till it has fomething lefs than half 

 its own weight of water, and carefully fet by to cool, it will 

 not cryftallize; but if a tremulous motion be given to the 

 veflel, or a cryttal of the fame fait dropped into it, the 

 whole fuddenly cryftalHzes, exhibiting a beautiful appear- 

 ance. When the cryftals are expofed to the air, they lofe 

 their water of cryftallization, and alfume the form of white 

 powder. In this change they lofe about 60 per cent, of 

 their weight, as will be feen in their analyfes. 

 According to Kirwan, it is compofed of 



Sulphuric acid - - 23.52 



Soda - - - - 18.48 



Water - - - 58. 



100 



Accord- 



