74 Calcareous Genus. S E C T I O N VI. Calcareous Genus. Under this head I comprehend all thofe earths and ftones, apparently homogeneous, in which calcareous earth predominates. \ft Sfecies. Native Lime. ' Whether this really exifts has been rnuch quef- tioned; its exiftence, however, is not naturally improbable, fince feveral ftones contain uncom- bined calx, as appears by various analyfes; and that lime once fornied may remain a long time uncombined, even though expofed to the atmo- fphere, äs evident from common experience. I have found lime in lime kilns, of which a great part remained unfaturated four years after it was burned; but feveral refpeftable teftimonies efta- blifh its real exiftence. Dr. Woodward teils us, that a whitifh gritty earth, found at Clipfton ftone pit in Northamptonßiire, was found by Dr. More ton to contain lime, and make a cement, bv barely mixing it with water. Dr. Falconer of Bath. a man of unqueftionable Ikill and judge- ment in matters of this nature, informs us, that 3 he