MINERALOGY. 125 



iis et jovis mixta : Spuma Lup? 7 or Wol- 

 fram *. 

 1. With coarfe fibres. 



a. Of an iron colour, from Altenberg 

 in Saxony. This gives to the glafs 

 compofirions, and alfo to borax and 

 the microcoimic fait, an opaque whitifri 

 yellow colour, which at lad vaniflies. 



SECT. CXVIII. 



Observations on the Manganes e. 



Though it may feem difficult to many, to diftin- 

 guifh the kinds of manganefe by their appearance, 

 or external marks ; yet -it is extremely eafy to 

 know them by experiments made in the fire, if 

 attention is had to the above-mentioned pheno- 

 mena (Se£t. cxiii.). From hence it is not difficult 

 to comprehend why manganefe has hitherto been 

 either omitted, or erroneously ranked in fyftems, 

 viz. becaufe it has, like many other mineral 

 bodies, been examined only by fight, while the 

 more troublefome method of examining it in the 

 fire, has been overlooked. 



Some might perhaps imagine the manganefe 

 to be the remainder of fome metal, which cannot 

 be reduced aga ; n into its metallic ftate -, but it 

 ought to be remembered, that no metal can, by 

 any means yet known, be brought to an abfolutely 

 irreducible earth or calx, unlefs perhaps by the 

 burn;- ■ and therefore there is no reafon to 



fufpecc that nature gives fuch a production. Ig- 



* Wolfram is a name which is alfo fometime? given to 

 mock lead, and fometimes to cockle, or fhirl, as alfo to other 

 mineral* ; however, it is chiefly given to this fpecies of man- 

 ganefe, when i: occurs in the an -mines. E. and D. C. 



no ranee 



