■57ft
Little can be said with confidence concerning the characters of this-metal in a pure state. Chemists have usually obtained it in detachedglobules, rather than in a well fused mass. It is said to be grayishwhite, brittle, and very hard. Its spec, gravity, according to Allenand Aiken, is 17.22; while Guyton found it to be only 8.34 in a wellfused mass.
It is fusible in the most intense heat only. Both the metal andits oxide are nearly insoluble in acids; but the oxide, when digestedin nitric acid, assumes a lemon yellow color.
Species 1. Calcareous Oxide of Tungsten. !
This ore has the general aspect of a stone ; but its spec, gravitylies between 6,57 and 6.06. Its colors are gray or whitish, yellowishwhite or yellowish gray, sometimes with a tinge of brown. Its surfacehas often a resinous lustre, and is sometimes tarnished. It is moreor less translucent, or even semi-transparent, when crystallized. Itmay be scratched by a knife, and is easily broken.
Its fracture is foliated, but often imperfectly, and in some direc-tions is uneven or conchoidal; its lustre is shining and a little res-inous. The laininse separate in directions parallel to the sides bothof a cube ami octaedron.
It is sometimes amorphous, and frequently in crystals, whosegeneral form is an octaedron, bounded by isosceles triangles. Or itmay be called a double four-sided pyramid, of which any two contigu-ous sides, belonging to opposite pyramids, contain an angle, at thecommon base, ot 115° 36'. This octaedron is sometimes cunei-form—or bevelled on its lateral solid angles, or on the common base.—The primitive form is also an octaedron, but more acute, than theone just mentioned.—Sometimes also it presents the primitive octae-dron with its summits and oblique lateral edges truncated.
( Chemical characters.) It becomes opaque before the blowpipe,and decrepitates, but is infusible. l>y digestion in nitric acid, it isconverted into a yellow powder, which is the oxide of Tungsten . Acrystallized specimen from Schlackenwald yielded Klaproth yellowoxide of tungsten 77.75, lime 17.60, silex 3.0 ;=98.35. Anotherfrom Bitsberg yielded Scheele oxide of tungsten 65, lime 31, silex 4.
(Distinctive characters.) The preceding characters, and moreespecially the yellow color, which its powder assumes in nitric acid,
* Schcel. Wxuner. Scheelin. IIaut. It was discovered by Scheele .
f Sclieelin calcaire. IIaui. IIkonaniari'. Schwerstein. Webnsb. Tung sten , Kin. wan. Jawksos. La Pierre pesanle. Brochast.
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