For thy better knowledge thou mayst prove the stones, with white fusile glass, which thing is treated of in the fourth part of the Philosophical Furnaces, that thou mayst not have cause to impute the fault of thy errour to me; therefore I would have thee understand, viz. that all stones contain not gold, neither in all is it separable by the spirit of salt: they are therefore to be known before they be applyed to the work.
Now follows the preparation of flints, and the extraction of the gold contained in them, by the spirit of salt.
First the flints being made red hot in the fire, they must be quencht in cold water, after taken out and cooled, and finely powdered.
N. B. When they are broken in a Mortar the better parts may easily be separated from the baser: for while they are finely powdered, always the best part goes into red powder first, the worser part thicker and harder, containing little or nothing, being left; And if they be coursly powdered and sifted through a fine sieve the more subtle part like red powder goes through the sieve, the unuseful part being left in the sieve like white dust, which may be cast away: and if yet some redness appears, it must again be powdered in a Mortar, and the better part shall go into a red powder, the baser part being left in the sieve hard and white which is to be cast away, but you must observe that not all and every of these flints are thus separable by powdering; for some being beaten do every where retain the same colour, without any separation of the better parts, which you must finely powder and extract in the whole substance, But they (viz. those separable) are more easily extracted, because all the gold contained in one pound for the most part may be gathered out of three or four ounces finely powdered and separated in the aforesaid manner; so that it is not needful to extract the whole stone, nor to spend so much spirit of salt. But sand and clay need not such a preparation, but without a preparation being made before, are extracted by the affusion of the spirit of salt.
℞ then of the flints as aforesaid prepared and separated two, three, four, six pound, to which being put into a cucurbit of glass whole (undivided) pour of the spirit of Salt to the depth of three or four fingers breadth, and place it in hot sand or Balneo, that there the spirit of salt may be hot, and may extract the Gold, and so let it continue for five, six or more hours space, until the spirit tinged with a deep redness, can extract no more. And perchance at the first time (though seldom) it may not be tinged with so great a redness, then must you decant that same imperfectly tinged spirit, and pour to other flints after the manner expressed, prepared in another cucurbit, and place it with the flints in a moderate heat for to extract the gold; which done pour it off again, and pour it to fresh flints, and do so often until it hath drawn to it a sufficient quantity of gold; which afterward thou must keep, until thou hast gotten a greater quantity, and all the Gold may be separated at one time from it, as afterward shall be said.
Which done pour to the reserved flints in the first cucurbit, a fresh spirit of salt, and leave that so long in heat, until it be coloured, and extract the gold that is left in the flints, and was not at the first time extracted; which spirit being afterward decanted, pour it to the flints reserved in the second and third cucurbit, to extract the residue of the gold which was left at the first time; and so consequently to the others reserved, until the spirit be sufficiently coloured, and can attract no more; which afterward pour off and put it to the first, which was reserved. You must also pour a fresh spirit to the remainder of the extraction for the extracting of all the gold. At length pour to it also common water to wash away the tinged spirit of gold remaining in the flints, that none of the Gold may be lost.
And this labour is so long and often to be repeated till there remain neither flints nor spirits; in the mean while you should cast away the flints extracted and washed, that the cucurbits may be filled with fresh flints, and so continue the work; and if there be no more spirit left to continue the extraction, you may then separate the extracted gold from the spirit, which is done as followeth: but first you must have plenty of glass vessels, or retorts of the best earth, which may retain the spirits; which you may so far fill with the impregnated spirit, that the spirit in the abstraction run not over, which done, it is to be extracted in a dry Balneo by little and little from the Gold, which spirit ye may use again in the aforesaid work. And the Gold which is left in the bottom of the vessels, is to be separated from the vessels with a crooked iron wier and (kept being very like to red earth) for its use, until thou hast gotten a good quantity, viz. so much as sufficeth for separation and purgation (of which afterward) to be made by Antimony.
N. B. But when thou shalt extract red talc with spirit of salt, red or black granates, Smiris, or Lapis Calaminaris, and other Fossiles, which beside fixt Gold contain much immature and volatile Gold; you must in the abstraction cast in a little iron, viz. to the solution, which retains and fixes the gold which otherwise flyes away in fusion. Wherefore those solutions and extractions of Talc and other things containing volatile gold are better extracted out of iron Cucurbits by earthen alembicks than out of glass and earthen retorts, because then that volatile gold doth attract only so much thence as is sufficient for its fixation; which iron is after easily separated by the Antimony from the gold, as shall after be taught. And this is to be noted, that not the whole granate is soluble in the spirit of salt, although it be long left in digestion, always retaining its former colour; wherefore there is a difference to be made, or a preparation to be learned, requisit for the solution of the gold contained in them.
And you must extract Talc not with too much or excessive heat, lest its substance be totally dissolved in the spirit and be a hinderance to the work; because there is little profit then, for it is therefore appointed, that a little gold dispersed in a great quantity of Talc may be reduced into a little compass that it need not that all the quantity of Talc be made fusile, because it will thereby procure loss. But there is no danger in flints, because the spirit of salt doth not dissolve them as it doth Talc, but only extracts gold from thence, the stony body being left. The lapis calaminaris may also otherwise be handled in the extraction and fixation than granates, flints and Talc, because it is almost wholly soluble in the spirit of salt; which work is not here to be handled, because the extraction and fixation is taught in a peculiar way in another place, neither do I mean to treat of it here, but only of the extraction of gold out of flints every where to be found. And this is the way of extraction of Gold out of flints and sand in heat by the spirit of salt, to be done in glass vessels. But there is another way too, which is done in cold without glass vessels, which I thought worth the setting down, that in the aforesaid work you may choose which you please, this or that, and it is done as followeth. We must have in this way store of earthen funnels well burnt, and not sucking up the spirits; for want of which we must have such as be of strong glass: there must also be a form with many holes in it to receive the aforesaid funnels, under which must be placed glass dishes or basons to receive the strained spirit.