MINERALOGY. 25 



1. Pure Selenites. 



A. Tranfparent, Spatum Gypfeum diaphanum. 



a. Colourlefs, from Swifferland. 



b. Yellowifh, from Mont-martre near 

 Paris. 



2. Spar like Gypfum, Marmor metallicum. 



This ftone, on account of its heavinefs, 

 which comes near to that of tin or iron, is 

 iufpected to contain fomething metallic •, but, 

 as far as is hitherto known, no one has yet 

 been able to extract any metal from it, un- 

 lets fome traces of iron, which is no more 

 than what all other gypfa contain. 



A. Semitranfparent, Spatum Bononienfe^ the 

 Bononian ftone or phofphorus. Its fpeci- 

 fic gravity is 4,500 : 1000. 



B. Opaque. 



a. White, 



b. Reddifh, are found in Wildeman, at 

 Hartz, and in otxher German mines. 



3. Liverftone, fo called by the Swedes and 

 Germans *. See Seel. xxiv. 



* Mr. MargrafThas publifhed foirie curious experiments in 

 the Memoirs of the Academy at Berlin, about the quality 

 thefe fpars have to yield a phofphorus ; and has fhewn, that 

 every gypfeous earth is fit for it, provided metallic particles 

 are not predominant in it : now, as the Bononian fpar, 

 which is ponderous is of this fpecies, and is the moft fit to 

 be brought to a phofphorus, it is evident, that no metallic 

 mixture is the caufe of its weight. Mr. SchefFer, in the Me- 

 moirs of the Academy at Stockholm, for the year 1753, has; 

 communicated fome experiments upon a ftone of this kind 

 from China, which prove that it perfectly agrees with the de- 

 fcriptions given in feveral books, of a ftone called Petuntfe 

 by the Chinefe, and which, it is faid, is ufed in their China 

 manufactories. Th2 phofphorus of Baldwin illuitrates Mr. 

 MargrafPs experiments. The phofphorefcent quality of 

 j:hefe Hones is, however, different from that of the fparry 



Jjmeftones 



