52 AC COUNT of n MINERAL 



enumerated, as well as in others, a confiderable difference 

 adually prevails. 



53. Their fpecific gravities differ, that of native carbonate 

 of barytes being 4.338, while that of Strontitic fpar goes from 

 3.650 to 3.726. The laft mentioned parts with its acid ibme- 

 what more readily, and without being fufed itfelf, or adding fo 

 powerfully on the clay of the crucible ; and when calcined, it 

 imbibes moifture with much greater avidity, fplitting with 

 more heat and noife. There fubfifts a greater difference be- 

 tween the folubility of pure Strontites in hot and cold water 

 than of barytes * ; moreover, the forms of their cryftals dif- 

 agree widely. Strontites generates with fulphuric acid a lefs 

 ponderous and more foluble earthy fait than barytes. It is true 

 that both barytes and Strontites form cryftallizable falts when 

 combined with nitric or muriatic acids, but the cryftals have 

 no fimilarity either in property or afpecfl. Thofe, into the com- 

 pofition of which Strontites enters, fuffer changes from expo- 

 fure to the air, which do not happen to the nitrate or muriate 

 of barytes, and they are vaftly more foluble in water. In the 

 figure of the cryftals alfo the difference is very remarkable. A 

 ftrong and weighty argument in favour of the diftindl nature 

 of thefe earths is furniilied by the circumftance, that folutions 

 of Strontites in acids fuffer no decompofition from pruffiate of 

 lime or potafs ; for here I put out of confideration the change 

 that is occafionally produced when the minute portion of iron 

 is prefent ; while, as every body knows, a prominent and dif- 

 criminating feature of barytes is its precipitation bv either of 

 thefe fubftances. A mark of diftindlion not lefs decided is the 

 quality that Strontites and its compounds poffefs of tinging the 

 flame of combuftible bodies of a red colour ; a property that 



does 



* I have, fince this paper was read, difcovered that the difference of folubility of 

 barytes in hot and in cold water is fully as remarkable as that of Strontites. This 

 mark of dillinftion coniequently mult be rejedled. 



