XIX. The manner of reducing the Metals that are not gotten out of the Waters by precipitation, but are freed from them by abstracting them.
The Metals which are extracted out of the Mines, and freed from the waters by the abstracting of the dissolvent, cannot be so pure as those are which settle to the bottom by precipitation. For it is very rare for Gold and Silver to be found in metalline Veins, Stones, or Clay, without being commixed with other Metals; because for the most part, Copper is mixt with Silver, and Copper or Iron with Gold, the which being unseparated in the reduction makes the Gold and Silver impure. But now in the precipitation one Metal is freed after another from the Menstruum, and are not mixed with each other. But on the contrary, in the way of abstracting it, all the metals remain mixt together without any separation, and require a new separation and consequently a double labour, and more expences.
This inconveniency may be easily remedied by him who is versed in the knowledge of my dry separation of Metals. I have mentioned it in divers places of my writings, So that it would be needless to trouble the Reader with a superfluous rehearsal of the same in this place.
But forasmuch as every one hath not by him all my writings, I believed that it would be worth while, if I should here set down that Laver or Bath which washeth off the Metals with the help of Salt peter by the dry way. For, without the knowledge of this Artifice of separating the extracted Metals from each other, there would be yet requisite much labour, and much costs for the obtaining of the said Metals. But they are very easily, and with little labour, and with small costs separated the one from the other by the way here by us described, and indeed with more gain than is wont to be had by the way of precipitation.
And even as in the precipitation of Metals there is always some [portion] of the Waters, that puts on the nature of Salt Peter, viz. when the Waters that have been used, which are as it were the Seeds of Salt Peter, are implanted in an Alkalisate Salt, and so do multiply themselves in a wonderfull manner.
So likewise in the dry separation of Metals, there is in a manner, yet more Salt Peter gotten, viz. thus when they are separated in the melting Pots, from each other by Salt Peter, and by an artificial precipitation of one Metal after another, the Salt Peter you used is rendred fixt and Alkalizated, which Alcalizated niter is to be accounted of, as the root of Salt Peter. This root being implanted in acid Salts, is in like manner enriched with a plenteous encrease, and reduced into natural and inflamable Salt Peter; for, by it do the sharp Waters get to themselves the nature of Salt Peter, from those Alkalizate Salts. And if so be you seek not after the common Salt Peter, it is better to sow the Seed of Salt Peter (that is, some spirit of niter which you have used) into the appropriate root of Salt Peter, that is, into fixt niter. For by that means you will have (at the encrease) a wonderfull Salt Peter, which, in all operations, doth far more powerfully act than the common Salt Peter, what way soever it be mundified by; which is evidenced in my foregoing first Century.
Therefore forasmuch as in the separation of Metals by the dry way, there remains (after the operation is over) so much fixt Salt Peter as there was of nitrous Water in the moist extraction, it always abundantly supplies both Seed and Root of Salt Peter, so that they may be exceeding plentifully multiplied by other Salts, nor will you have any need of buying any more new Salt Peter for the now spoken of Labour. Verily this is a most compendious way, not onely of separating all Metals even in fusion, but also of somewhat bettering them, as shall be afterwards demonstrated.
XX. By what means such Gold as is commixt with Iron, or Copper, and from which (being extracted out of the Minerals) the dissolvent has been drawn off, is to be reduced.
Let such unclean Gold be commixed with two or three parts of its weight of the Glass of Lead, and melt them in a strong Crucible. If there happen to be much Iron, it will of its own accord yield a leaden Regulus, which being forced by the heat of the Fire in a Cupel will leave your Gold pure, because the Glass of Lead is wont to attract unto it self Iron and Copper. But if so be there is but little Iron mixt with your Gold the Regulus of Lead will not separate or precipitate in the melting, and therefore as it melts some filings of Iron are to be added, and to be accurately stirred with a red hot Iron, that so a Regulus of Lead may fall to the bottom, bigger or lesser according to the muchness or littleness of the Iron you added.