370 Elements of Mineralogy. 



ing a blue colour to alkalis, to be common 

 to thofe different metallic fubftances in which 

 we find it ? 



Manganefe. 



According to Mr. Rome this ferni-metal is 

 a mixture of iron, zinc and cobalt : that it 

 contains iron is not denied ; but it is afferted, 

 that befides iron it contains a peculiar femi- 

 metal, whofe properties are independent of 

 the prefence of iron, fince they are abfo- 

 lutely different from thofe of iron, and every 

 alloy of iron with any other known metallic 

 fubftance, and are fo much the more appa- 

 rent, as the portion of iron it contains is 

 diminifhed. Neverthelefs, Mr. Rome objects 

 that the regulus of manganefe can never be 

 totally freed from iron, and that all the ex- 

 periments hitherto made upon it being made 

 on a mixed femi-metal, the properties dif- 

 covered by thefe experiments ihould be 

 deemed thofe of a mixed, and not thofe of a 

 fimple fubftance. But the fallacy of this 

 reafoning will readily appear, if it be confi- 

 dered that, though until lately, platina could 

 not be obtained perfectly free from iron ; yet 

 the moft judicious chymifts in Europe, Lewis, 

 Margraafi Schejfer, Macquer and Baiime, were 

 of opinion that it was a peculiar diftincl: me- 

 tallic fubftance; and at this day regulus of 

 antimony and tin are never abfolutely free 



from 



