34$ .Tie Uses 



are of themfelves fufRciently fluxile : and that it is 

 of no manner of fervice to rocky matters alone, 

 may eafily appear, upon doling barely with py- 

 rites fuch matters, were they without all eyes of ore, 

 and were neither foft flags, nor any leady additi- 

 ons employed therein. And thus pyrites aids, or 

 aids nor, according as itfelf is or is not aided. It 

 is in .itfeif ftubborn, yet becomes foft and flowing, 

 according as it is treated or dofed : whence it is 

 neceflary to eqnfider the refractorinefs and ea- 

 fifnefs of ores in general to flux : and 'tis owing 

 either to the ores ^hemfelves, or to their mineral 

 admixtures. In themfelves, glitter, white and green 

 lead -ores, antimony and yejlow pyrites or copper- 

 ores are loft-flowing : but white pyrites more ftub- 

 born, yet fmelting in a brifk fire, even when un- 

 ft ripped of its arfenic : more ftubborn is the yel- 

 lowifh pyrites^ which apart difficultly or not at all 

 cakes : mod ftubborn of all is mock- lead, and 

 next, the earths of pyrites , cobald and bifmuih, or 

 their capita mortua or remainders: yet thole of the 

 yeilo.wifh more than thofe of the white ; as the for- 

 mer hold more metallic, namely martial, but the 

 latter, more unmetallic . earth : Thofe of cobald 

 and bifmuth are highly unmetallic (fo far as our 

 experience hitherto goes) and hence not to be fluxed 

 without falts, as we learn from the fmalt-glafs : and 

 as ores hold thefe three metals, lead, copper, and 

 iron, they in proportion prove either hard or foft 

 flowing, as thefe metals themfelves prove : for it is 

 known, that unmetallic earths flow mod: difficultly ; 

 iron, with difficulty \ copper, with more eafe, and 

 lead, with moft. In regard to their mineral ad- 

 mixture, all ores are properly ftubborn ; though 

 quartz, compared with any other, fcorifies per fe with 

 the moft eafe -, but with additions, particularly lead, 



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