CALX aerata (calcareous earth mild), contaminated by ſiliceous earth.
Siliceous.
CALX aerata (calcareous earth mild), contaminated by clay and ſiliceous earth. (See § 115.)
Cronstedt Min. §§ 25. 28. Calcareous Marle.
CALX aerata (calcareous earth mild), contaminated by iron and manganeſe. Martial.
Cronstedt Min. §30. See alſo §203. Hæmatites.
There can be no doubt that the four firſt (§§ 94–97.), if not the laſt (§ 102), are genuine and diſtinct ſpecies; there is ſome difficulty as to the reſt, dependent, perhaps, only upon mechanical mixtures. If the heterogeneous matters can be diſcerned by the eye, we cannot heſitate to refer the ſubſtance to the ſaxa (ſtones); but in theſe the eye cannot diſcern them. Moreover, we know that the earths have a mutual attraction to each other, and form combinations more intimate than mechanical ones. Earth of alum, precipitated by a cauſtic alkali, and thrown into lime water, preſently loſes its pellucid and ſpongy texture, turns white, and condenſes, abſorbing the lime from the water, and forming an union not to be ſeparated but by chemical means.