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Gypsum is a compound of calcareous earth and vitriolic and ; 

 it forms a diftind fpecies of the calcareous genus of fofllls, of 

 which fpecies there are fix families. 



The general charader of this fpecies are 



1. Solubility in about 500 times its weight of water, in the 

 temperature of 60". 



2. Precipitability therefrom by all mild alkalis, and alfo by 

 cauftic fixed, but not by cauftic volatile alkali. 



3. Ineffcrvefcence with acids if the gypfum be pure ; but feme 

 families of this fpecies, being contaminated with mild calx, 

 {lightly efFervefcc. 



4. Infolubility, or nearly fo in the nitrous acid, in the ufual 

 temperature of the atmofphere. 



5. K J^ecific gravity ^xt^cYim^ixom 2,16 to 2,31. 



6. A degree of hardnefs, fuch as to admit being fcraped by 

 the nail. 



7. When heated nearly to rednefs it calcines, and if then 

 it be flightly fprinkled with water it again concretes and 

 hardens. 



8. It promotes putrefadion in a high degree. 



Of 



