1 68 Elements of Mineralogy. 



the argill and calx of iron, which will remain 

 imdiflblved. 



Of this acetous folution TOO grains fhould 

 be taken and examined with the Pruffian 

 alkali, if any part be precipitated it is pon- 

 derous Earth, and by heating this to rednefs 

 its weight may be known, or ftill better by a 

 previous experiment, determining the quan- 

 tity requifite to precipitate i gr. of acetous 

 barofelenltes, and by the rule of proportion, 

 the quantity of it in the whole folution may 

 be found. 



The remainder of the acetous folution, is 

 to be evaporated to drynefs, and heated white 

 in a clean polifhed iron crucible for two hours, 

 then weighed and thrown into hot diflilled 

 water, the calcareous Earth, (if any,) will be 

 diffolved in a fufficient quantity of this water, 

 of which an ounce can fcarcely diflblve i gr, 

 fo that frequent affufions of hot water may 

 be requifite; the magnefia will remain undif- 

 folved, and is to be dried and weighed, its 

 weight gives that of the pure calcareous Earth, 

 from which that of the ponderous (if any) is 

 to be deducted; the lime-water may alfo be 

 precipitated by an aerated alkali. 



Laftly, the argill and calx of iron, which 

 remained undiffolved by the acetous acid, 



are 



