Y T T 



the BUe : it was built near a town called Gafteinefre, fwal- 

 lowed up by an inundation of the fea fome centunes ago, 

 M inhabitants can.e to eftabli(h themfelves at this place. 

 The Dutch made tnemfclves mafters of it in the r^r 1604, 

 and fince that time it has been ilrongly fort.hed. wh.ch s 

 Lch amaed by us fituation. being furrounded by mor Ifo. 

 which they can lay under water at pleafure , 8 m.les i.. 

 ofSiuys.N.lat. 51^21'. E. long. 3° 28. 



YSIPORTAM, in Jncient Geography, a place ot Alia, 

 in Armenia, which had a Roman garnfon. 



YSNI, in Geography. See LsNV. r u u • 1 



YSOPUS, a term ufed by fome to exprefs the chemical 

 art of feparation. ... . 



YSPAR, a name by which fome of the chemical writers 



*^^YSSANDON, Jean, in Mujical Biography, born at 

 LefTart in the Compte de Foix, wrote " A Treatife on 

 Praftical Mufic, divided in Two Parts." This book is 

 become very fcarce, and deferves to be reprinted. It was 

 firft printed by Ballard in 1582. Laborde. 



YSSEL, in Geography. See Issel. 



YSSENGEAUX. See Issengeau.x. 



YSTAD, or Ydstad, a fea-port town of Sweden, on 

 the fouth coaft of the province of Schonen, from whence a 

 packet fails to Stralfund. It was formerly well fortified, 

 and contained two churches. The harbour is neither large 

 nor fafe ; 26 miles S.E. of Lund. N. lat. 55° 22'. E. 



long. 1 3° 44'- . , • r 



YSTLA, a town of North America, m the province of 



Mexico. 



YSTWITH. See Istwith. 



Y-TCHANG, a town of Corea ; 35 miles W.N.W. of 

 Kang-tcheou. 



Y-TCHUUN, a town of Corea; 15 miles S.S.W. of 

 Ou-tcheou. — Alfo, a town of Corea; 55 miles N. of 

 King-ki-tao. 



YTHAN, a river of Scotland, a few miles N. of the 

 Don, that joins the fea, about two miles from Aberdeen, 

 which falls into the German ocean. The Ythan is a ftream 

 formerly celebrated for its pearl filheries, of which fome 

 relics are now found. 



YTHER, a river of Wales, which runs into the Wye, 

 3 miles N. of Builth. 



YTTERON, a fmall ifland in the gulf of Bothnia. I>'. 

 lat. 63° 4'. 



YTTRA Bergon, a fmall iOand on the W. fide of the 

 gulf of Bothnia. N. lat. 6l* 48'. E. long. 17° 13'. 



YTTRIA, or Ittria, in Chemljlry, is a pecuhar ele- 

 mentary fubllance ufually confidered as an earth. 



Yttria has been hitherto met with in a peculiar mineral 

 named Gadolinite, fo named from profeffor Gadolin, who 

 firft analyfed it, and in Yttro-tantalite, both miaerals 

 found only in Sweden. See thofe articles. 



Yttria has the appearance of a fine white powder, without 

 tafte or fmell. It does not affeft vegetable blues. Its 

 fpecific gravity is confiderably higher than that of the other 

 earths, being no lefs, according to Ekeberg, than 4.842. 



Yttria is infoluble in water, yet, hke alumina, it is 

 capable, according to Klaproth, of combining with nearly 

 one-third of its weight of that fluid when precipitated from 

 a ftate of folntion by the muriatic acid. 



In foUitiona of the pure alkalies it is dikewife infoluble ; 

 but in the carbonate of ammonia, and indeed in all the 

 alkaline carbonates, it ditfolves readily. It combines with 

 acids, and forms with them falts, which, as far as they are 

 known, are defcribed below. 



Yttria is not affeQ:ed by light, and probably does not 



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combine with oxygen. According to the experiment! of 

 Klaproth, it does not combine readily with Uilpliur. 



Sir Humphrey Davy found, that when potafQum was 

 palfed through red hot yttria, it was converted into potafli, 

 while grey metallic particles were perceived mixed with 

 the alkali, which were confidered to be the metallic bafis of 

 the earth or yttrium. Nothing further, however, is known 

 refpefting this metallic bafis. 



The Salts of Titria are but little known. The following 

 only have been examined. 



Nitrate of Tttria. — This fait was firft. formed by Ekeberg, 

 and has been more lately examined by Vauquelin. It may 

 be prepared by diffolving yttria in nitric acid. The folu- 

 tion has a fweet aflringent tafte, and can fcarcely be made 

 to cryftallize. Expofed to the air, it deliquefces. When 

 fulphuric acid is poured into the folution, cryftals of 

 fulphate of yttria are inftantly precipitated. 



Carbonate of Tttria. — This fait may be formed by pre- 

 cipitating yttria from its folution in acids by means of a« 

 alkahne carbonate. It is white taftelefs infoluble powd»r, 

 compofed, according to Klaproth, of 



Carbonic acid 



Yttria 



Water 



18 



55 



27 



100 



According to Vauquelin, however, it lofes only 32 per 

 cent. when calcined. 



Phofpbate of Tttria. — Vauquelin formed this fait by 

 mixing a folution of the phofphate of foda with the fulphate, 

 nitrate, or muriate of yttria. The phofphate of yttria pre- 

 cipitated in the form of gelatinous flakes. 



Sulphate of Tttria. — Sulphuric acid diffolves yttria readily. 

 As the folution proceeds^ the fulphate cryftallizes in fmali 

 brilliant grains. Ekeberg ftates thefe cryftals to be flat fix- 

 fided prifms, terminated by four-fided fummits. Dr. Thom- 

 fon obtained thefe in the form of long flender rhomboidal 

 prifms. Their colour is amethyft-red : their fpecific gravity 

 2.791. They are foluble in about 30 parts of water at 60°. 

 A red heat partly decompofes them. Oxalic acid, prufEate 

 of potafh, and infufion of nutgalls, occafion a precipitate in 

 the aqueous folution of this fait. It is decompofed by the 

 phofphate of foda. The fulphate of Glucina is readily 

 diflinguifhed from this fait by its being colourlefs, lighter, 

 and more foluble in water. According to Berzelius, the 

 fulphate of yttria is compofed of 



Sulphuric acid 

 Yttria 



50.0 



50.0 



1 00.0 



Arfeuiate of Tttria. — When yttria is dilTolved in arfenic 

 acid, and the folution boiled, arfeniate of yttria precipitates 

 in the form of a white powder. Arfeniate of potafh alfo 

 precipitates yttria from acids. 



Chromate of Tttria. — Chromic acid diffolves yttria cold in 

 confiderable quantity, and with effervefcence. The folu- 

 tion has an aftringent and pungent tafte, and, like moft of 

 the chromates, has an orange-red colour, paffing into yellow. 

 The folution is quite neutral. When evaporated, it forms 

 minute prifmatic and cubic cryftals. It is very foluble in 

 water. 



Acetate of Tttria. — Yttria diflblves readily in acetic acid, 



and the folution on evaporation yields cryftals of the acetate 



of yttria, the form of which is ufually that of thick fix -fided 



12 plate;, 



