The Edulcorating-water out of which all the Metals are already reduced [or precipitated] being boil’d in Coppers, till a skin appear at top, and then poured out into other Coppers or wooden Vessels, yield excellent Salt-peter, fit for the distillation of Aqua Fortis for a new Operation. He that is skill’d in managing this work, will get as much Salt-peter as will pay the costs of the Aqua Fortis; insomuch, that the Gold is extracted without any costs. For five or six pound of Aqua Fortis, which holds in it two or three pound of dissolved Salt, and is precipitated with a sharp Lixivium of Calx-vive yields about some ten pounds of Salt-peter: and this will certainly answer the price of the Water or Aqua Fortis; and so you will have Gold extracted out of the Stones without expence or charges.
34. Another and better way of getting out the Gold that is Extracted out of the Oars, out of the Aqua Fortis.
Make, by Calcination, some Ashes, of one part of Tin, and four parts of Lead, and put them in an Iron-pot, whereto pour the extracted Gold, or the Aqua Fortis containing the Gold, boil it and continually stir the Calx with an Iron rod, that so all the sharp Spirits may cleave to the Lead and Tin ashes, and the Phlegm onely may exhale. After that the said Calx of the Metals hath concentrated all the Spirits, and is become wholly dry, let it be taken out, and be cast upon Coals in a secret Melting-pot or Crucible, in which operation the fire forceth out all the Spirits into the Recipient, which are to be again made use of for new Extractions. The volatile Gold, and which is mixt with Iron, adheres to the Calx of the Metals, and is to be reduced in the Furnace which the Germans call Stichofen; whereby the Lead impregnated with the Gold, and exalted by it, is gotten, which by reparation yields the Gold and Silver.
N. B. If that Lead should not contain Gold enough as to be worth the while of separating it on the Cupel [or Test] it is to be again commixt with Tin, and be reduced into Ashes, and by this Calx are new Extractions to be Concentrated, that so by the so many repeated Labours, the Lead is at length made rich enough, and yields (by separation) a good portion of Gold and Silver.
If (in the separating) the matter be turned by the blast of Bellows into Litharge, it is not needfull to melt such a deal of Lead on the Tests, which would require so much fire. But however, it is a thing feasable for the Gold to be gotten out of [or by] the Tests without melting, which shall be taught afterwards.
35. How an Aqua Regia is easily acquired for the Extraction of Stones.
Forasmuch as Spirit of Salt may be had in great quantity, you need onely dissolve some Salt-peter therein, and this Solution is to be used to extract the Minerals withall. For the Spirit of Salt being made stronger by the Salt-peter, doth readily and willingly seize upon the tender Gold that is in the Stones. And as for the Spirit of Salt, it may be used as it comes over in the first distillation without any rectification.
36. An easier way of getting an Aqua Regia usefull for extraction.
Because that these Operations do always bring forth Silver impregnated with Gold, and that Aqua Fortis is requisite to make the Separation of them; the Solution of Silver may be used, and so the labour of the aforesaid incineration be omitted. Into the Aqua Regia wherewith you have extracted the Gold, pour in a Solution of Silver, and it will fish out the greatest part of the Gold out of the Aq. Reg. and is, [viz. the Aq. Reg.] to be afterwards made use of to a new extraction, and be again divested of its extracted Gold by a Solution of Silver. In want of a Solution of Silver, the extract is to be concentrated with the Ashes of Lead, and you must proceed (by driving off the Spirit out of the Ashes, and by reducing the same Ashes in a Furnace,) after the same manner as we taught you but now in our foregoing directions.
N. B. You are here to note, that the Aq. Fort. which containeth in it the dissolved Silver, and is poured into the Aq. Reg. or nitrous Spirit of Salt, doth add an encrease unto these same Waters. For the Aq. Fort. doth corroborate the Spirit of Salt far better than Salt-peter doth.