H4 Catcareous Genus. Obfervations. Any ftone of a fine grain, conficlerable hard- nefs, and which admits of a good polifh, is in general called marble; but this denomination is now moftly confined to aerated limeftones. White marbles, and tranfparent fpars, are reck- oned che pureil of the aerated fpecies, and among the former that of Paros and Carrara; but this laß; we have feen to contain a flight proportion of argill and mountain cryftal ; and fome parts , of its immenfe beds, I am informed, are remark- ably replete with filiceous particles. Expofed to a heat of 700’ Fahr, for feveral hours, it lofes but of its weighc, therefore contains fcarcely any water. 41 Roz. 96. The white marble of Stannovai, near Cathar- inenburg in Siberia, contains, according to Mr. Georgi, 93 per ct. of mild calx, 6 of filex, and 1 of argill. It is the fame as that brought to Paris by Abbe de la Chappe. Spec. grav. 2,7185, per Brifion. Abbe Poda is faid to have difco- vered in it a portion of aerated barytes. 1 Ilaab, 287. . ' Black marble frequently contains iron; in that ufed in Paris, Mr. Bayen detefted 5 per ct. of iron ; but it derives its colour from bitumen moft probably, for it affords a white lime, 11 Koz. 496. The fpec. grav. of fine Italian marble is 2,7x2. The Chinefe founding ftone, called Hion Che, or Calcophonos of Pliny, is of this fpecies. The Duke de Chaulnes has fhewn it to confift of calcareous earth, with bitumen and iron. It has much
