Art. XVII. Additional Notice of the Tungsten and Tellurium, mentioned in our last Number.
Art. XVII. Additional Notice of the Tungsten and Tellurium, mentioned in our last Number.
Part I. Description of the Ore.
Colour, dark brown, almost black; brittle, powder a lighter shade of brown than the mineral; hard, scratches glass, scintillates with steel, with a red spark; a degree of polish produced, where the steel strikes, and when the steel is impressed upon it.
Structure compact, in some places slightly porous; lustre, generally dull, sometimes glimmering, and almost resinous.
Crystals octahedral. Specific gravity of three massive pieces, 5.7, 6. and 6.44 mean, 6.05 nearly; probably that of the crystals would be higher.
Infusible by the blow-pipe even with borax, and does not by strong ignition impart any colour to it or to potash; not magnetic, even in fine powder, nor after being heated red hot on charcoal, and in contact with burning grease.
Many specimens decrepitate violently under the blow-pipe. When heated on coals in pieces of considerable size, they often explode with a smart report, and are thrown in fragments sometimes several yards from the fire.
Gangue quartz; accompanying minerals in the same vein, native bismuth, native silver, galena, iron and copper pyrites, much magnetic pyrites, blende, &c.
Geological relations. The country is primitive, and the immediate rock which forms the walls of the vein is said to be gneiss; (we have not seen it.)
Locality, town of Huntington, parish of New Stratford, county of Fairfield, 20 miles west from New-Haven, Connecticut.
Remark. Native bismuth in small quantities, has been for several years obtained from this mine, but the shaft has been sunk only about ten feet.
Part II. A variety of the Ore.
General characters as above, but on some parts, there is seen a whitish, or yellowish, or sometimes darkish metallic substance; it is in thin plates, like the leaf metals, and sometimes reticulated, and graphic in its disposition; it is soft and easily cut with the knife. In the specimens examined, it was so much blended with the other ore, and so trifling in quantity, that it was not possible to separate it mechanically, so as to examine it separately.
Part III.—A. Chemical Trials.
1. Muriatic acid, hot or cold, produces no effect; hot nitro-muriatic dissolves the ore with energy, red fumes are evolved, and generally a red solution obtained, from which ammonia precipitates red oxyd of iron abundantly.
2. A heavy lemon-yellow powder remains, insoluble of course in acids, but easily and completely soluble in warm ammonia.
3. A dark powder, in diminished quantity, again appears, more acid dissolves it in part, and again reveals the yellow powder, which ammonia again dissolves, and so on, till nothing remains but some portion of the gangue.
4. The ammoniacal solution, which contains the oxyd of tungsten, is decomposed by acids, and by heat, and instantly deposits a white heavy powder, becoming yellowish by standing, and full yellow by heat.
5. This powder is infusible by the blow-pipe, but ignited with borax in a platinum crucible, it became of a superb blue, like smalt, or between that and Prussian blue.
6. The quantity obtained was too small to make it convenient to attempt its reduction to the metallic state; no doubt remained, however, that it was oxyd of tungsten, or as it is sometimes called, tungstic acid.
7. There were traces of manganese, and all the facts perhaps justify the conclusion, that the ore is very similar to the ferruginous tungsten or wolfram.
8. The calcareous tungsten occurs in octahedral crystals, but we have not before heard of this form in the ferruginous species, which generally affects the prismatic forms.
B. remark.
We had been for some time inclined to believe, that the above ore was ferruginous tungsten, but although fortified by the opinion of Col. Gibbs, we were withheld from announcing it, because the form of the crystals, the specific gravity, the colour, and perhaps some other characters, were not perfectly accordant with European descriptions, and with the specimens in our possession, which are from Saxony and Cornwall.
During the necessary chemical trials (which have, we trust, established the correctness of the above opinion,) we very unexpectedly discovered in some of the ores of tungsten, proofs of the existence of tellurium. The conclusion was induced by the phenomena, for nothing was farther from our expectations.
Two fragments were pulverized by an assistant, and we therefore cannot say whether they had any external characters different from those of the other pieces; they came, however, from the same part of the vein, and their powder resembled that of the other pieces.
1. Digested in nitro-muriatic acid, a straw-yellow solution, slightly inclining to green, was obtained, and a black powder was left behind.
2. More acid digested on this powder, gave a deep red solution of iron, and left the yellow oxyd of tungsten, which being dissolved in ammonia, the black powder again appeared, and so on, as under 3. Part III.
3. The solution 1, diluted largely with water, deposited an abundant white precipitate, which was very heavy and rapidly subsided.
4. Alcohol and ammonia, respectively produced the same effect, only more decidedly.
5. This precipitate, evidently an oxyd of a metal, being collected on a filter and dried, exhibited the following properties.
6. Heated by the blow-pipe on charcoal, it was instantly volatilized in part, and in part decomposed, with an almost explosive effervescence; numerous ignited globules of metal appeared on the charcoal, and burned with an abundant flame of a delicate blue colour, edged occasionally with green.
7. In many trials, these results always occurred, and sometimes a peculiar odour was perceived, at first thought to be owing to arsenic, but it was incomparably feebler, and somewhat resembled that of radishes.[72]
8. Zinc, iron, and tin, plunged into separate portions of the nitro-muriatic solution, precipitated abundantly a black flocculent substance.
9. On charcoal before the blow-pipe, this substance was very combustible, with a blue flame, and was completely dissipated in the form of white oxyd, with the above smell.
10. Some of it was obtained on the charcoal in metallic globules; it was a brittle metal, white, with a tinge of red, and foliated, but not so distinctly as bismuth and antimony.
11. The filters on which the white oxyd had been deposited, burned almost with explosion, nearly as rapidly as if they had been soaked with nitrate of potash, or of ammonia, and the characteristic blue flame appeared while the burning lasted.
12. Other experiments were made upon the metal, (not the oxyd.) It gave to strong sulphuric acid, (simply by standing in it in the cold) an amethystine colour, which disappeared as the acid grew weaker, by attracting water from the air.
13. With nitric acid it formed a colourless solution, not decomposed by water.
14. It did not dissolve in muriatic acid, till a few drops of nitric acid were added.
15. The white oxyd heated with charcoal in a small coated recurved glass tube, afforded brilliant metallic globules, which rose by distillation, collected in the bend of the tube, and resembled drops of quicksilver, except that they were solid.
C. remark.
The above facts having induced the conclusion that the metal, thus unexpectedly discovered in the ores of tungsten, was tellurium,[73] we were led to search for external characters by which to judge what specimens contained it. The ores from Transylvania, (the only telluric ores with which we are acquainted,) bearing no analogy in appearance or composition to those before us, we were led to inquire whether the tellurium in these latter ores was in combination with tungsten, or merely in mixture. The external characters detailed in part II, tend perhaps to fortify the latter opinion. If we mistake not, we there found a proper ore of tellurium mixed with a proper ore of tungsten, but we have also by chemical means, found tellurium where similar external characters were not apparent. Before the appearance of our next Number, we hope to obtain purer and better specimens. In the mean time we add the following facts.
1. A crystal, and a massive piece of the kind described under part I, and specimens of two varieties of those described under part II, were digested in nitro-muriatic acid.
2. Both oxyd of tungsten, and oxyd of tellurium were obtained from all of them.
3. Many specimens have been examined which have afforded tungsten only, and no tellurium.
At a convenient time, it is hoped that a more complete examination of this subject may be presented to the public.
In the mean time, we may submit to mineralogists and chemists, whether if this is not a new mineral, it is not at least a new association of two minerals before known. It has not been forgotten that gold and silver are frequently combined with tellurium: neither of them has, however, been discovered, (although sought after by proper tests) during the above trials.
Yale College, March, 1819.