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water be added, Co that its fpecific gravity be about 1,3, it is 

 gently foluble ; but if nearly its own weight of water be added 

 10 it, fo that its fpecific gravity be 1,22, it effervefces violently, 

 vvliereas barytes is nearly infoluble in an acid even thus diluted. 

 This folution alfo cryflallizes ; and, if the evaporation be flow, into 

 large cryftals ; by fpontaneous evaporation I have obtained feme 

 of the weight of 14 grains, and if the quantities were large their 

 fize would undoubtedly be greater. Their fhape was that of flat 

 hexahedral lamellas imbricated, that is, fuperimpofed on each 

 other, as flates on the roof of an houfe. 



These cryftals are foluble in fomewhat more than their 

 weight of water heated to 66^. Placed on a red-hot iron they 

 decrepitate like common fait, and fufe in a ftill ftronger heat. 



The faturate folution of this earth does not difcolour litmus, 

 as that of barytes docs. 



To the Acetous Acid. 



This ftone is alfo foluble, though much more flowly, in diftilled 

 vinegar. The folution being carefully evaporated ftioots into 

 ftelliform cryftals, of an acid tafte ; they efflorefce by expo fu re 

 to the air. 



To the Vitriolic Acid. 



This acid, when concentrated, has fcarce any adion on this 

 ftone, whether mild or calcined. When much diluted I found 

 10,000 parts of it to diflTolve one of this ftone. 



SECTION 



