Now then that you may get out the reliques of the Gold out of the leaden Glass you must proceed the following way.
XII. By what means the Glass of Lead which as yet contains in it some reliques of Gold is to be dealt withall, that it may let them goe out of its body.
Melt that Glass of Lead in a well covered pot, that I mean in which you suppose some Gold to be, and being well molten cast in a little iron filings, and mix it well by stirring it with an iron rod, and leave it in the fire thus molten, for one quarter of an hour, that the sulphur of the Glass may be killed by its corroding of the iron, and may let fall a leady Regulus wherein the Gold will be, and which (in the first melting) the Glass held up, will separate it by the Cupel from the Lead.
N. B. But here you are to observe that the filings of the iron are to be used very sparingly to this precipitation; for by how much the more iron is added, so much the greater will the Regulus of the lead be, and consequently require a greater Cupel, which is not so necessary.
For put case the Glass of Lead in which the Gold is suspected to be is about one pound weight, and there is but about a Quinta, or certain small weight of Gold; now it is not necessary to have any more than one Lot of Lead or thereabouts, precipitated thereout of into a Regulus, to which precipitation is required no more than one Lot of the filings of Iron. For the Regulus of Lead precipitated out of the Glass, doth for the most part answer in weight, to the weight of the Iron filings used about the precipitation, or to speak more clearly, you will get so much leaden Regulus, as the Iron is you added.
The remaining Glass becomes black and is unprofitable for any farther melting with Gold, but yet needs not be cast away, because those Scoria’s do yet contain much Lead, and therefore serve to be mixt with such Pots as you have used and broken about Metals, or with other wild and hardly fusile metallick Veins, to render them fusible, being I say commixt with these, and put in the Furnace which the Germans call Stichofen, do not onely yield forth all their Lead, but withall draw out the Metals out of those matters which were mixed with them in the melting. But they are principally profitable for the melting and reducing of those Metals, which do not onely very difficultly admit of fusion by themselves, but withall do, being mixed with the Ashes of Tin, so much the more difficultly suffer themselves to be reduced by melting, unto their former bodies. But in defect of such Metals and Minerals, as are not but with much adoe tamed by Liquefaction, you may put to that black Glass of Lead, one fourth part onely of filings, or Scoria’s of Iron made into powder, that so both the matters thus commixt may be molten in the Furnace Stichofen. So by the addition and help of the Iron, all the Lead will be reduced to its former body, and will withall extract out of the Iron whatsoever of Gold and Silver lay therein hidden; so that by this means there may be reaped a great benefit from this reduction of the Glass of Lead. But yet that Lead is to be tryed by a foregoing tryal, whether or no it be rich enough in Gold and Silver to quit the costs of separation? For if it be not, it must be used to the afore described incineration, that so there may be no loss either of the Gold or the Lead.
XIII. The preparation of the Glass of Lead, for the reducing such Gold as being precipitated by the Liqour of Flints, is of difficult fusion.
Take of white and fusile Flints [or Pebles] one part, and of Minium, or any other Ashes of Lead, or else even of Litharge it self four parts, each of which being powdered apart, you are to commix and melt them well in a strong double Pot, then pour them out, and you will have a Hyacinth-coloured Glass, the which Glass is to be powdered and mixt with the Gold, and it makes the Gold Powder which resisteth melting fusible.
XIV. Another way of reducing Gold precipitated by the Liqour of Flints.
To one part of this hardly-melting Gold which is precipitated by the Liqour of Flints, admix two or three parts of Litharge, which matters put in a strong double Pot, and cover it well, and melt them well down in a Wind Furnace, that the Litharge may draw unto it self all the Flints, and all the Gold may separate. Having separated the Regulus from the Scoria’s of the Lead, you must precipitate these Scoria’s, which do as yet hold in them some small portion of Gold into a small leaden Regulus, with the filings of Iron, as we shewed you but now, that so you may also have even that residue of Gold. The Scoria are conserved by being reduced in the Furnace Stichofen, according to the operation already spoken of.