CAR
( 265 )
CAR
t$f boiling water: a confiderable abforption ofcaloric takes place during its folution. It isliardly at all foluble in cold alcohol, and requiresabove 200 parts of this fluid when boiling forits compleat folution.
It has been analyfed both by Bergman andPelletier: each of thefe chemifts agrees in theproportion of alkali, but they differ materiallyin their eftimation of the water, and carbonicacid.
Bergman Pelletier43 48 potafh
20 43 carbonic acid
32 9 water
100
100
The tafte of this fait is cool and frefh withhardly any of the alkaline flavour; on which ac-count, and becaufe it is fully faturated withcarbonic acid, it is greatly preferable to com-mon fait of tartar in the compofition of effer-vefcing drafts, and for other medical purpofes.It is neither efflorefcent nor deliquefcent in theair. It is decompofable with abftraction of itsacid by barytes, and lime, and ftrontian, andwith abftraction of its alkali by all the mineral,and almoft all the vegetable acids.
The ufes of potafh are innumerable. It isconfumed in the greateft quantities by foap-boilers, bleachers, and glafs-makers. In thelaboratory it is in conflant and indifpenfablefervice.
CARBONAT OF SODA. Carbonate deSoude , Fr. Kohlenfaure mineralifche gervachfal-ialt, Germ.
Kelp. Soude de Varech, Fr. Barilla . Na-tron.
This fait is found to exift both in the mineraland vegetable kingdoms of nature. When mine-ral, it is met with either difl'olved in the waterof certain hot fprings, as thofe of Carlfbad inBohemia, and Rykum in Iceland , or of certainlakes, as the natron lakes of Egypt and Hun-gary ; or it occurs in the ftate of a folid fait asthe foffil natron of Tripoli , called Trona.—In the vegetable kingdom carbonat of foda hasbeen proved to exift ready formed in the falfolafoda, and in all probability is contained in allthofe fucculent faline plants that grow in places-impregnated with muriat of foda. In order tofupply the ; vaft demands for carbonated foda itas procured from both the fources above-men-tioned- by procefles which we fhall now relate,beginning with the mineral foda.
• Phil. Tranf. 1». P-J67
There are two varieties of mineral foda, theftriated and the compact. The ftriated hashitherto been procured only from Africa . It isfound in the province of Sukena, between Tri-poli and Fezzan , forming a very thin ftratumjuft below the furface of the foil: it is of a ftri-ated cryftalline texture refembling ftriated gyp-fum, and from fome fpecimens defcribed byDr. D. Monro,’ 1 the ftratum (which does notexceed an inch in thicknefs) is in contact bothabove and below with common fait. From theaccount of Mr. Bagge, however, it appears thatthe natron diftridt is at a confiderable diftancefrom the fait mines, and the analyfis of this fub-ftance by Klaproth exhibits no trace of muriaticacid in its compofition. It is collected to theamount of fome hundred tons annually, butfcarcely ever finds its way to the Europeanmarkets. It is charadleriftic of the ftriated fodathat its cryftals inftead of efflorefcing as thisfait ufually does, remain permanent in the air,a circumftance that is to be attributed to thecomparatively fmall quantity of water of cryf-tallization that it contains, and to the compleatfaturation of its alkaline bafe by carbonic acid.Common carbonated foda confifts of
22 foda
16 carbonic acid
62 water
100
whereas the trona, according to an accurateanalyfis of it by Klaproth , b confifts of
37 foda
38 carbonic acid
22.5 water
2.5 fulphated foda
100.0
The compact mineral foda or natron, althoughcontained in the waters of feveral fprings andlakes, is procured in quantity only from Egypt and Hungary . The Egyptian natron lakes, fixin number, are fituated in a barren valley, calledBahr-bela-ma, about thirty miles weftward ofthe Delta. During three months in the yearthey are fupplied with water from copious. fprings that burft out from the weftern fide ofthe valley, but as they receive no water during• the reft of the year fome of the fmaller and: fhalloweft ones are generally dried up duringthe fummer. The foil confifts of calcareousrock mixed with gypfum, and for the moft part* Analyt. Eff. ii. p. 63.
2 b
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