The Copper may also be precipitated out of a solution of Blue Vitriol by the interposition of a Fixed Alkali. This precipitate is of a greenish blue colour, and requires a much greater quantity of the black flux to reduce it.
Copper dissolves in the Nitrous Acid, in the Marine Acid, and in Aqua regis; from all of which it may be separated by the same methods as are here ordered with regard to the Vitriolic Acid.
[CHAP. IV.]
Of Iron.
PROCESS I.
To separate Iron from its Ore.
Pound into a coarse powder the martial stones or earths out of which you design to extract the Iron: roast this powder in a test under the muffle for some minutes, and let your fire be brisk. Then let it cool, beat it very fine, and roast it a second time, keeping it under the muffle till it emit no more smell.
Then mix with this powder a flux composed of three parts of Nitre fixed with Tartar, one part of fusile glass, and half a part of Borax and charcoal-dust. The dose of this reducing flux must be thrice the weight of the ore.