Copper. 261 



date by means of iron, though it is not eafy 

 to get it pure, if the nitrous acid be the 

 folvent. 



14. I have found that 112 gr. of good 

 iron, precipitate 100 of copper from a faturate 

 and dilute folution of it in the nitrous acid, 

 and 80 gr. of the fame iron precipitate, 100 

 of copper from a faturate and dilute folution 

 of it in the vitriolic acid ; fo that weigh- 

 ing the iron before and after, the quantity of 

 copper may be eftimated by the lofs of 

 weight of the iron ; but care muft be taken 

 that the iron do not remain in the nitrous acid 

 after the copper is precipitated. Experience 

 will point out fome other precautions too 

 tedious to be inferted here. 



15. If iron be mixed with the ore, it may 

 be feparated by long boiling in nitrous acid. 



1 6. In the dry way, after torrefaftion, they 

 may be eflayed by melting them with I or I 

 of their weight of borax, and 1 of their weight 

 of pitch. Some lofs always attends the black 

 flux. Thus Mr. Fontana having eflayed 576 

 gr. of a calciforrn ore by black flux, obtained 

 but 376 or 380 of copper, yet by diftillation 

 he got 408, u Roz. p; 511* 



S * SPECIES III. 



