By the Count de Bournon, F.R.S. &c.
Foreign Secretary of the Geological Society.
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This substance is a combination of lime and sulphuric acid, in the
proportion, according to Vauquelin, of 0,40 lime and 0,60 sulphuric
acid. It has obtained various names : being called Chaux Sulfatée
Anhydre by Haüy, Chaux Sulfatine by Brongniart, Anhydrite and
Würfelsath by Werner, Muriacite by Poda and Klaproth, Pierre de
Vulpino by Fleuriau de Bellevue, and Marmo bardiglio di Bergamo by
the Italian statuaries. The name sulphate of lime has hitherto been
applied to gypsum; but as it is now well known that the simple
combination of lime and sulphuric acid produces bardiglione, while
water is essential to the composition of the former, that expression
is inapplicable, and might be supplied by that of Hydro-sulphate of
lime.
Essential specific Characters.
Primitive Crystal. A rectangular tetrahedral prism with square bases, which, from every indication, do not belong to the cube, but
