Calcareous Genus. 33 



It contains about 30 per cent* vitriolic acid, 

 3$ of mere Earth, and 38 of water; of 

 which it parts with about 20 by calcination. 

 The beft method of decompofmg it is to boil 

 it, well pulverized, in a fixed alkaline lye. 



The varieties of its external appearances 

 may be prefented under two feries, the 

 tranfparent and opake. 



SERIES I. 



Iranfpartnt. 

 Lapis Specularts, Vitrum Ruthenicum, Clacks 



Stirium Pellucidum, Gypfum Spa* 

 thofum Diaphannm. 



This is either colourlefs, or yellowifh* 

 green, or reddifh ; which laft colour is from 

 iron, as Mr. Morveau has, by means of 

 vinegar, completely feparated it. Its form 

 is either amorphous, or regular, generally 

 cubic 5 its texture lamellar, fcaly, or 

 fibrous. 



SERIES II, 



Opake. 



The colour of this is either white, grey, 

 greenilh, or black j its texture 

 D fcaly, 



