[ 305 ] 



expofed to the flame by themfelves, they will be" 

 found inftantly to melt, and part of their fulphuf 

 to go off-, the copper may afterwards be obtained 

 in two ways : the one, by keeping the proof in 

 fufion for about a minute, and after iuffering it to 

 cool ; when it will be found to have a dark and 

 uneven appearance externally, but which, after 

 being broke* difcovers the metallic copper of a 

 globular form in its centre, furrounded with a re fc 

 gule, which {till contains fome fulphur and a por 

 tion of the metal: the other, by being melted 

 with borax, which hit way fometimes makes the 

 metal appear fooner. 



SECT. XLIL 



The Miner a cupri pyritacete, containing copper* 

 fulphur, and iron, may be tried with the blow-* 

 pipe, if they are not too poor : in thefe experi- 

 ments the ore ou^ht to be calcined, and, after 

 that, the iron fcorifled. For this purpofe a bit of 

 the ore muft be expofed to a flow flame, that as 

 much of the fulphur as poflible may part from it, 

 before it is melted, becaufe the ore commonly melts 

 very foon, and then the fulphur is more difficult 

 to drive off. After being melted, it mull be kept 

 in fufion with a ftrong fire, for about a minute, 

 that a great part of the iron may be calcined : and, 

 after that, lb me borax mud be added, which 

 fcorifies the iron, and turns with it to a black 

 flag. If the ore it very rich, a metallic copper 

 will be had in the flag., after the fcorification : if 

 the ore is of a moderate richnefs, the copper will 

 ftill retain a little fulphur, and fometimes iron : the 

 product will therefore be brittle, and mult with 

 great caution be feparated from the flag, that it 

 may not break into pieces ; and if this product h 



X sitter- 



