. 



38 Elements of Mineralogy. 



with the nitrous or marine, it affumes a yel- 

 low colour, as Mr. Woulfe firft obferved. 

 Phil. Tranf. 1779, p. 26. 



When heated it burfts, becomes reddifh, 

 jnelts very difficultly per fe ; nay, according 

 to Mr. Bergman^ it is infufible with the blow 

 pipe, and not totally fufible even with the 

 affiftance of fixed alkali, but eafily by borax;, 

 and without effervefcence. It alfo eafily melts 

 with its own weight of fluor, 



Its conftituent parts were difcovered by 

 Mr. Bergman and Mr. Scheele^ nearly at the 

 fame time, but firft publifhed by Mr. Scheele 

 in the Swediih Memoirs for 178 1. It appears 

 to contain about i its weight of calcareous 

 Earth, and the remainder a peculiar acid of 

 an earthy appearance, and iron. 



This acid is feparated from its earthy 

 by digefting the powdered ftone in three 

 times its weight of nitrous acid, and after 

 pouring off this acid, and edulcorating the 

 refiduum, digefting it again in cauftic volatile 

 alkali, after fome time the alkali is alfo poured 

 off, and the refiduum being edulcorated, is 

 again digefted in nitrous acid, and afterwards 

 jn volatile alkali : Thefe fucceflive digeftions 

 ^re continued until the greater part of the 

 ftone difappears, t;he nitrous acid conftantly 



taking 



