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 Pol i ers chiefer , 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 , . They are recognised with such distinctne 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 Francis bad, 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 bra and other metals. Mr. Phillips found in the Derby shire rotten-stone (near Bake well), 86 of alumina, 4 of silica, and 10 of carbon—being a remarkable difference in composition from the Bohemian.