RADIATED NATRON. 315 Geognostic and Geographic Situations. Mr Bagge, Swedish consul at Tripoli, has given the following information respecting this interesting subspe cies of natron. “ The native country of this natron, which is there called Trona, is the province Sukena, two days journey from Fezzan. It is found at the bottom of a rocky mountain, forming crusts, usually the thickness of a knife, and sometimes, although rarely, of an inch, on the surface of the earth. It is always crystalline : in the fracture, it consists of cohering, longish, parallel, fre quently radiated crystals, having the aspect ot unburnt gypsum. Besides the great quantity of trona which is carried to the country of the Negroes and to Egypt, fifty tons are annually carried to Tripoli. It is not adulterated with salt. The salt-mines arc situated 011 the sea-shore; hut the trona occurs twenty-eight days journey up the country According to the accounts of Mr Barrow, it would appear also to occur in the district of Tarka in Boshieman’s Land, in Southern Africa. • Uses of Natron. It is principally employed in the manufacture of glass, in the manufacture of soap, in dyeing, and for the wash ing of linen. It is sometimes purified before it is used, but more frequently (particularly that from Egypt) it is used in its natural state. In Hungary, particularly at Debrezin, it is used in great quantity in the manufacture ot soap : it has been also employed in considerable quantity in Scot land and England for the same purpose. In Siberia a fine white glass is manufactured with it. In the Levant, the natron of Suckena is mixed with tobacco, in order to give it • Baggc, in the AbhancU. cl. Schwed. Acad. v. j. 1773, b. xxxr. s. 131.