74. 



CHEMICAL ANALYSIS OF SOME CALAMINES. 



A Chemical Analyfis offome Calamines. By Ja mes Smithson, 

 Esq. F. R. S. P. R. S. From the Fhilofophical TranfaC' 

 tionsfor 1803. 



Refcarches of 

 Bergman on 

 Calamines. 



Hauy's opinon 

 that they are 

 pure oxides. 



"Experiments, 



Calamine from 

 Biejberg. 



Xxternal cha- 

 racters. 



IN OT WITHSTA NDING the experiments of Bergman a nd 

 others, on thofe ores of zinc which are called calamine, much un- 

 certainty flill fubfifted on the fubject of them. Their conflitution 

 was far from decided, nor was it even determined whether all 

 calamines were of the fame fpecies, or whether there were fe- 

 vera! kinds of them. 



The Abb6 Hauy, fojuftly celebrated for his great know- 

 ledge in cryftailography and mineralogy, has adhered, in his 

 late work *, to the opinions he had before advanced f , that 

 calamines were all of one fpecies, and contained no carbonic 

 acid, being a fimple calx of zinc, attributing the effervefcenc^ 

 which he found fome of them to produce with acids, loan ac- 

 cidental admixture of carbonate of lime. 



The following experiments were made to obtain a more 

 certain knowledge of thefe ores ; and their refults will fliow 

 the necefiity there was for their farther inveftigation, and how- 

 wide from the truth have been the opinions adopted con- 

 cerning them. 



Calaininefrom Bleyherg. 



a. The fpecimen which furnifhed the fiibje6l of this article, 

 was faid by the German of whom it was purchafed, to have 

 come from the mines of Bleyberg in Carinthia. 



It was in the form of a Hieet ftalactite, fpread over fmall 

 fragments of limeftone. It was not however at all cryftalline, 

 but of the dull earthy appearance of chalk, though, on com- 

 parifon, of a finer grain and clofer texture. 



It was quite white, perfedly opaque, and adhered to the 

 tongue; 68.0 grs. of it, in fmall bits, imnierfed in dillilled 

 water, ablbrbed 19.8 grs. of it, =0,29. 



It admitted of being fcraped by the nail, though with fome 

 difficulty: fcraped with a knife, it afforded no light. 



• Traitide Mineralogiet Tome IV. f ycurnal des Mines. Nei 32, 



#S.l grs. 



