But if so be that any one has a mind to precipitate the Metals extracted out of poor Mines, after the manner prescribed in the Appendix, to the intent he may after the precipitation make Salt Peter of the remaining Waters, he may reduce the Calx’s of the Metals, and principally of the Gold very easily and without any loss, by this following way.
IX. The manner of reducing the precipitated and washed Calx of Sol without any loss.
The precipitation of Gold by Lixiviums, Liquor of Flints, Spirit of Urine, Solution of Mercury, hath been clearly enough described in the [Appendix to the fifth part of the prosperity of Germany]; but yet the reduction of the same was past over in silence, because of the too much hast of the said Book. Therefore it seemed unto me necessary to insert the same here, for their sakes, who have but little knowledge, or in a manner none at all in these affairs; for should I go to propound such a thing for the skilfull Chymists, I should but do what is already done, especially because he deserves not the name of a Chymist who is ignorant of the reduction of the solar Calx.
But forasmuch as it may so happen, that even the unskilfull may set about this extracting of the Minerals, and yet be ignorant of the way of reducing the Gold though they should have extracted it; therefore have I judged it not amiss to illustrate that reduction by my describing thereof here, the which being divers, according as the precipitation is made by such or such a means, doth also require different operations.
X. The reduction of the solar Calx precipitated by the Liquour of Flints.
Albeit that Borax reduceth every Calx of Sol to its former body, if it be therewith mixed and melted in a Crucible, yet that would prove too dear, if somewhat a greater quantity thereof be required for the reduction; for there must be of it at least twice or thrice as much in weight as is of the Gold, if you would have a due reduction of the Gold made. The reason is this, because the Flints precipitated to the bottom together with the Gold, and so sticking on to the Gold impead its fusion so that it cannot rightly come together into its due body. Hereupon is it necessary that there should be the double or treble weight of Borax added to the Gold if you would have all your Gold return unto its former body without detriment.
But whereas there are also other matters to be found which make the Gold fusible and are not so dear as Borax is, the use of such things is to be admitted, but especially when a great quantity of Gold is to be reduced. Otherwise if it be but little Gold that is to be reduced, and you have not the aforesaid matters at hand, one may for such a small trial use Borax. But where there is a greater quantity to be reduced the following matter will be found to be far more profitable and beneficial.
XI. How the Gold which is precipitated by the Liquor of Flints, is to be melted without Borax, by the Glass of Lead only, which is of a far meaner price.
Take of your Gold precipitated by the Liquor of Flints and dryed, one part, of Glass made of Lead and beaten into powder, three parts; the which mix well with the Gold and put into a Crucible, which said Crucible let be put into another bigger one (for which operation the Hassion pots are most fit) that so if the Gold chance to flow out of the inner pot, it may stay in the outer and be conserved. For the Glass of Lead is of such a nature that it usually perforates or runs through the pot. Having thus done put your twofold Crucible containing your commixed matters into a wind Furnace, such an one as I have described, and when you have covered it, put Coals under it [or about it] and urge your fire for one quarter of an hour, that all may well flow, then pour it out, and separate the Regulus of Gold with a stroke or two from the glass of the Lead; which said Glass hath attracted to it self all the flinty matter, and suffers the pure and malleable Gold to settle to the bottome into a Regulus.
N. B. If your glass of Lead be still yellow as it was before the operation, ’tis a sign that all the Gold is separated therefrom; but if it be of a green colour ’tis a sure sign that it has as yet some Gold mixed with it. For Gold being mixed with Glass shews its being there by yielding a skie-colour, the which skie-colour is necessarily changed in the yellow glass of Lead into a green; because every yellow and skie colour do in their commixtion beget a green.