'24 ACCOUNT of a MINERAL 



rytes and liiTie, holds a fort of intermediate fpace, and forms a 

 kind of link between them. To illuftrate what I mean, I may 

 cbferve, that in fpecific gravity, fufibility, capability of decom- 

 pofition by heat, and in the folubility of the compounds it 

 forms, it fcands in the middle. Thus, heavier than calcareous 

 and lighter than barytic fpar, it is more eafily melted than the 

 one, lefs fo than the other. When fubjeded to heat, it parts 

 with its carbonic acid more readily than barytes, lefs fo than 

 lime. The fulphate, nitrate and muriate of it are all more fo- 

 luble than the fame falts of barytes, and lefs foluble than thofe 

 of lime. In one refpecl ^indeed it exceeds both, and that is, 

 folubility in hot water, which perhaps is fo great as may make 

 fome perfons, over fond of nice diftin(5lions, deny it a place 

 among the earths altogether *. 



57. This kind of intermediate fituation fhall perchance in- 

 duce fome to imagine, that this earth is a peculiar combination 

 of the other two. At firfl:, I confefs, when this idea fuggefted 

 itfelf to me, I did not deem it improbable ; but now, after full 

 invefligatlon, I muft rejedl the notion. This, I hope, I do 

 with good reafon, fince I have found that, like the acknowledg- 

 ed fimple earths, this fubflance bears repeated folutions, cry- 

 flallizations and precipitations, without fliowing the fmalleft 

 difpofition to a feparation of principles ; and fince the means 

 that difunite an artificial mixture of the two earths, fuch as 

 diJTolving in muriatic acid and cryftallizing, or precipitating 

 by pruffiate of potafs or lime, have no effe(5l in occafioning a 

 disjun6lion of its parts. 



58. As the earthy bafis of the Strontian fpar pofTefTes re- 

 markable qualities that are peculiar to it, and forms with acids 

 combinations unlike thofe generated by the known earths, and 

 differs from all of them in the order of its attradions, I can- 

 not hefitate to conclude, that it is an earth fui generis, a new 



2 and 



* Vide note to 53, 



