£4 The NAMES 



natural, that it ought not to be received but with 

 fome caution, and under many reftrictions. The 

 druggifts feem to underfland by it bifmuth^ and the 

 alchymifts, who indeed generally affect confufiori 

 and obfcurity, have made it to exprefs not only bif- 

 muth) but alfo regulus of antimony \ fpeltcr, and moll 

 of the known femi-metals. Among the mine- men, 

 particularly thofe of Mifnia, by marcafite, accord- 

 ing to the bell information I could get, is meant 

 our pyrites, or kies •, not generally, but only when 

 finely angular, fmooth, and efpecially of a cubical 

 form, and of a gold- glittering caft. On the con- 

 trary, another, though broke off from this very 

 piece, which in the frefh break has the very fame 

 colour, and which affords the fame contents, if it 

 happens only to differ in the external figure, is not, 

 On any account, allowed the name otmarcqfite. 



Under the, like circumflances of confufion and 

 ambiguity, the term Magnefia has been introduced 

 into the hiftory of the pyrites ; particularly by al- 

 chymical writers, as Flamellus *, who gives this 

 denomination to the .pyrites Achai<e -, and Bohnius f 

 ufes the fame expreffion (with the addition of Vi- 

 triolata, on account of its eafy refolution in the air) 

 to denote the Heflian iron-earth, which is a real, 

 and indeed a firfl-rate kies. Howevef, among mine- 

 people, and in common language, the term is 

 very little* if at all known, except with the glafs- 

 makers, who mean by it a martial mineral, more 

 commonly called brown-flone, of a dufky colour, 

 xather inclining to black, and fpicular, like anti* 

 mony. Its ufe in the glafs-houfes is to give a due 

 whitenefs and tranfparency to the better fort of 

 glafs : the potters alfo employ it in glazing their 

 manufactures. In Italy it is known by the name 

 of Manganefe< But though the word Magnefia is 



not 



* Theatr. Chym. T. IV. p. 863. 



f Bohnii Difct. Chym. IV. p. 10& 1 j 



