TUNGSTEN, in mineralogy, is usually of a yellowish and greyish white : it oc cilia massive, disseminated, and very fre quently crystallized ; it sometimes occurs in large, coarse, and small granular dis tinct concretioni, with streaked and shining surfaces'. ,Its specific, gravity is from 4.3 to 6. It is infusible; without ad dition, before the blow-pipe. It melts with borax", but seascely changes its co lour. When pulverized ,and digested with nitrous or muriatic acid, it leaves a yellow residue, which is the Oxide of tungsten. .The niineral contains, accord ing to Scheele, Yellow oxide of tungsten E5 Lime 31 Silica • ' 4 100 . , This specimen was obtained in Sweden a specimen from Cornwall, analyzed by Klaproth, yielded Yellow oxide of tungsten 75.25 Lime . .... 18.70 Oxide of iron . . . 1.25 manganese . . 0.75 Silica . 1.50 97.45 Loss . . . 2.15 • s " P 100 It ()dears in primitive mountains; and be longs to the,,oldest metalliferous forma tions. It is usually accompanied with tinstone, wolfram, quartz, mica, steatite, fluor-spar, &c. The Cornish tungsten is accompanied with iron-stone and hema tite. It is found in Cornwall, Sweden, Saiony,' and Germany. It is distinguish ed from finstone by its octahedral crys tals, the intensity of its lustre, its hard: rless„ an its greater specific gravity. When Bergman analyzed this mineral, he conjectured that the basis- of the acid might a metallic substance. This me tallic has been only found in the state of acid, in combination with lime, iron, manganese, and lead. When it is combined with lime, it is the tungsten of the Swedes ; and in combination with iron, it is called wolfram. To obtain this metal from the acid, it is mixed with char coal in a erosible, and exposed to is very strong heat. By this process the metal
was obtained in the form of a small but ton at thq3olorn of the crucible, in the first experiments which 'were made upon it by the German chemists. This crumb led to pieces b'etween the fingers ; and when it was examined with a magnifying glass, it Was fimnd to consist of a number of metallic globules, none of which were larger than a pin head. The colour of this metal is a steel grey. The specific gravity is 17.6, or, according to others, 17.22. It is on of the hardest '.oftthe metals. It is also else of the most infusi ble, requiring a temperature of 170° Wedgwood.
It crystallizes on cooling., When it is heated in the open air, it is readily con verted into a ydllow oxide, which after wards, by a stronger heat, becomes of a black colour ; and then by combining with a greater proportion of oxygen, it assumes the character of an acid, namely, the tungstic acid, whose properties and Combinations with alkalies and earths will be presently described.
Tungsten combines with phosphorus, forming a phosphuret, the-properties of which are unknown. It also combines with sulphur, forming a sulphnret of a bluish black colour, and which may be crystallized. There is no action between this metal and-sulphuric, nitric, or, mu riatic acids. It is only acted on by nitro muriatic acid at a boiling temperature, and nitrous gas is disengaged. Nothing therefore is known of the combinations of tungsten with the other acids. This metal combines with the other metals, and forms alloys with them.