TRAVERTINO. See [Tufa].
TREACLE, is the viscid brown uncrystallizable syrup which drains from the sugar-refining moulds. Its specific gravity is generally 1·4, and it contains upon an average 75 per cent. of solid matter, by my experiments.
TRIPOLI (Terre pourrie, Fr.; Tripel, Germ.); rotten-stone; is a mineral of an earthy fracture, a yellowish-gray or white colour, composition impalpably fine, meagre to the touch, does not adhere to the tongue, and burns white. Its analogue, the Polierschiefer, occurs in thin flat foliated pieces, of the above colours, occasionally striped; soft, absorbent of water; spec. grav. 1·9. to 2·2.
M. Ehrenberg has shown that both of these friable homogeneous rocks, which consist almost entirely of silica, are actually composed of the exuviæ or rather the skeletons of infusoria (animalcula) of the family of Barcillariæ, and the genera Cocconema, Gonphonema, &c. They are recognised with such distinctness in the microscope, that their analogies with living species may be readily traced; and in many cases there are no appreciable differences between the living and the petrified. The species are distinguished by the number of partitions or transverse lines upon their bodies. The length is about 1⁄288 of a line. M. Ehrenberg made his observations upon the tripolis of Billen in Bohemia of Santafiora in Tuscany, of the Isle of France, and of Francisbad, near Eger.
The meadow iron ore (Fer limoneux des marais) is composed almost wholly of the Gaellonella ferruginea. Most of these infusoria are lacustrine; but others are marine, particularly the tripolis of the Isle of France.
According to the chemical analysis of Bucholz, tripoli consists of—silica, 81; alumina, 1·5; oxide of iron, 8; sulphuric acid, 3·45; water, 4·55. This specimen was probably found in a coal-field. The tripoli of Corfu is reckoned the best for scouring or brightening brass and other metals. Mr. Phillips found in the Derbyshire rotten-stone (near Bakewell), 86 of alumina, 4 of silica, and 10 of carbon—being a remarkable difference in composition from the Bohemian.
TUFA, or TUF, is a gray deposit of calcareous carbonate, from springs and streams.
TULA METAL, is an alloy of silver, copper, and lead.
TUNGSTEN (Eng. and Fr.; Wolfram, Germ.); is a peculiar metal, which occurs in the state of an acid (the tungstic), combined with various bases, as with lime, the oxides of iron, manganese, and lead. The metal is obtained by reduction of the ore, or the deoxidizement of the acid, in the form of a dark steel-gray powder, which assumes under the burnisher a feeble metallic lustre. Its specific gravity is 17·22.