TEL 



TEL 



ToUurium amalgamates very impcrfeftly with mercur^', 

 even when heat is apphed. It combines with fiilphur in 

 equal proportions when fufed in a gentle heat, and forms 

 a lead-coloured llriated fubilance. With nitric acid, tel- 

 lurium yields a limpid coloiu-lefs folution, which is not ren- 

 dered turbid by water. In the concentrated fohition, very 

 light, llender, ncedle-fhaped cryftals are formed, which com- 

 monly aflume a dendrilical arrangement. Muriatic acid, on 

 the addition of a little nitric acid, affords a fimilar clear folu- 

 tion of this metal. This faturated folution is decompoied 

 by the mere addition of water, which throvi's down a white 

 powder, but this is again diffolved on adding more water. 



The powder thrown down is not a pure oxyd of tellurium, 

 as it is conibined with a fmall quantity of muriatic acid. 

 If tellurium be expofed to one hundred times its weight of 

 concentrated fulphuric acid, the acid gradually acquires a 

 tinge of a fine deep amethyftine red. This colour is de- 

 ftroyed by the addition of water, and by heat. 



Carbonated and pure alkalies precipitate tellurium in 

 tlie form of a white oxyd, combined with water or an 

 hydrate. This is rediflblved by an excefs of alkali. Al- 

 kaline fulphurets throw down a dark -brown or blackifh pre- 

 cipitate. Tinfture of gaUs produces a flocculent yellow 

 pi-ecipitatc. The folutions of this metal in acids are not 

 decompofej by pruffiate of potalh, a property which tel- 

 lurium poflcfTes in common with gold, platina, iridium, 

 ofmium, rhodium, and antimony. Zina and iron precipi- 

 tate tellurium from its folution in acids, in the metallic ftate, 

 in the fliape of blackifh flocculi, which acquire a metallic 

 luftre by trituration. Phofphorus is gradually coated with 

 metallic laminx in a muriatic folution of tellurium. 



Oxyd of tellurium on charcoal is reduced with briflc effer- 

 vefc*nce, and afterwards volatilized ; but if heated in a 

 firnall glafs retort it fufes, and on refrigeration exhibits a 

 ftraw-yellow colour and a ftriated texture. Some of thefe 

 properties of pure metallic telliu-ium are common to native 

 tellurium. Since the firil difcovery of this metal by Kla- 

 proth, it has been further afcertained, that it combines 

 with chlorine in the proportion of lOO parts of tellurium 

 with 90.5 of chlorine. Tellurium forms two diftinft com- 

 pounds with hydrogen, the one of which is folid, and the 

 other gafeous. The firft is formed by making tellurium 

 the negative lurface in water in the Galvanic circuit; by this 

 a brown powder is produced, which is a folid hydruret of 

 tellurium. The fecond is formed by afting with dilute 

 fulphuric acid upon the alloy of tellurium and potaflium, by 

 which a peculiar gas is produced, having a fmell refembling 

 that of fulphuretted hydrogen. It is abforbed by water, and 

 a claret -coloured folution refults, which by expofure to the 

 air becomes brown, and depofits tellurium. After being 

 wafhed with a fmall quantity of water, this gas does not 

 afFeft vegetable blue colours. It burns with a blueilh flame, 

 depofiting oxyd of tellurium, and imites with alkalies. It pre- 

 cipitates moil metallic folutions, and is itfelf inftantly de- 

 compofed by chlorine gas. It may be called telluretted 

 hydrogen gas. 



Tellurium is one of thofe metals whofe oxyds poffefs the 

 charafters of acids, and form diftindl; clafTes of falts. The 

 falts formed by a combination of a bafe with the oxyd of 

 tellurium, are called by Berzelius tellurets. 



Tellurium, according to Klaproth, combines with oxygen 

 in the proportion of 100 parts of the metal with 20.5 of 

 oxygen ; but Berzelius determines the proportions to be 

 ICO tellurium and 27.83 oxygen. 



This metal has not hitherto been apphed to any ufeful 

 pjrpofe in the arts, which may probably be attributed to its 

 fcarcity, and the comparative recentnefs of its difcovery. 



Tellurium Mines. — " The mine of Nagyag is diftant aljout 

 5 



ij-niiles from Deva, in the bannat of Temefwar : it is fitu- 

 ated ill the heights of the mountains, lying on the north 

 iide of the river Moros. After croffing the river, we began 

 to climb thefe heights. The roads were not bad, but almoft 

 the whole journey to Nagyag was up a fleep afccnt. We 

 were five hours, although drawn by four horfes in a light 

 car, before we reached the fmall town where the mine has 

 been opened. 



" As Tranfylvania is the only country in the whole world 

 where tellurium has been difcovered, our curiofity was 

 greatly excited to view the Nagyag mine. At laft the pro- 

 fpeiEl opened upon us with great boldnefs of fcenery quite 

 among the fummits of this mountainous region, and in a 

 manner highly pifturefque and ftriking. The fituation of 

 the mine was diftinguifhed by an immenfe heap of difcarded 

 minerals thrown out in working it. 



" The whole village of Nagyag has been undermined : the 

 works are not only carried on upon a grand and extenfive 

 fcale, but they are condufted with a degree of neatnefs, 

 for which the Germans have long been famous in mining. 

 Some fpecimens of tellurium are fo exceedingly rich in 

 gold, that in the falj of them for the crown, it is neccffary 

 to weigh them, and to eftimate the price according to 

 the quantity of gold they contain. This kind of ore is 

 always kept locked up in private warehoufes. The com- 

 mon ore lies expofed in heaps, at which the workmen are 

 bufily employed in preparing the ore for ftamping. 



" When the mine was firft difcovered, the mountains around 

 it were covered with forefts, which have fince been cut 

 down to fupply the mines with timber. The difcovery of 

 the mine is thus related on the refpeftable authority of bai-on 

 Boon, in his letter to profefTor Feber. ' A Wallachian, 

 whofe name was Armenian John, came to my father, then 

 pofTefled of a rich filver mine at Cuertes, telling him, that 

 as he conflantly obferved flames iffuing from and playing 

 upon a fiffure in ihe Nagyag foreft, he was of opinion that 

 rich ore might be hid under ground. My father was fortu- 

 nate enough to liften to the poor man's tale ; and accord- 

 ingly he drove a gallery in the ground which the Walla- 

 chian had pointed out. The works went on iome years 

 without fuccefs, and my father had refolved to give them 

 up. However, he made a laft drift towards the fiffure, 

 and there he difcovered the black and lamcllated gold ores, 

 which were at firft looked upon as iron glimmer, but proved, 

 when affayed, to be, what they really are, rich gold ores." 

 Travels through the Bannat, Lend. 1799. 



" Other veins were afterwards difcovered running parallel 

 to each other from north to fouth, and dipping from weft 

 to eaft. When Boon vifited Nagyag, the mine had only 

 been worked to the depth of 60 fathoms. Its depth is 

 now 150 fathoms. The mountains are entirely compofed 

 of porphyry, covered with red clay or red flate and fand- 

 ftone. The veins break off as foon as they reach the red flate. 

 Thefe veins contain with the ore, felfparand fat quartz. There 

 is alfo found here a very rich kind of ore, which is finely 

 woven into the texture of a reddifh felfpar. Among the 

 rich ores, native filver occurs mixed with gold. Another 

 variety is called by the miners cotton ore ; it confifts of little 

 native filvery gold grains in tellurium, adhering to an argil- 

 laceous matrix. All the femi-metals at Nagyag are found, 

 when carefuUy analyfed, to contain gold. According to 

 Boon, the tellurium mines in the courfe of 20 years yielded 

 above 4,000,000 florins in gold and filver. At the time of 

 our arrival it had been worked 60 years, and was equally 

 produftive." 



TELLUS, Terra, S> in yf/i/onomy. See Earth. 



TELMARA, in Ancient Geography, a town of Afia 

 Minor, in Caria. 



TELMEEN, 



