None has reflected that the mineral kingdom must naturally be acidic and corrosive throughout if nature is to thin and dissolve raw stones and earth and cook them into metal. Nor have they considered their assumption that they must immediately introduce the mineral-corrosive medicine into animal nature just as it comes from the fire, although nature itself has set an evident wall and curtain between animals and minerals. They have always bypassed that wall—the vegetable kingdom, an intermediate nature between them—or, if they used it, applied it contrariwise. With seeing eyes they have been blind, failing to notice that when joining two opposing things they needed a middle. Therefore they have prepared nothing but corrosive medicines, or ineffectual precipitates and powders. They themselves know what they achieve with them.

Now back to the matter. In the chapter on the vegetable kingdom I said that acid contracts, constricts, is styptic and astringent, and so forth. Here I have said it makes things volatile. To prevent anyone, as far as I can perceive, from convicting me of contradiction, I shall untie this point too. Where nature adds little acid to much earth, it makes only binding, constricting, astringent things: iron, antimony, bloodstone, red chalk, lodestone, emery, bole, and so forth. The small amount of acid clings strongly to such earth and dissolves it; if central heat is too strong and sudden, it fixes and dries into those difficultly fusible ores. Where heat is not too strong and acid or corrosive comes somewhat more abundantly, it makes somewhat fusible ores and metals. Because of more acid and less or weaker drying and fixation, they remain open and only slightly permanent, like iron and copper. Conversely, where acid arrives in excess, it makes volatile ores, as operation can demonstrate. Take chalk or quicklime, pour on a little spirit of nitre, vitriol, sulphur, or salt, or a common corrosive acid oil, and draw it off strongly until completely dry. Then calcine it in an assay dish under a muffle or in a crucible: it becomes a styptic earth and fusible. If it was styptic before, it is now more so, and the acid allows itself to be calcined and fixed with the chalk.

Pour more acid upon the same earth, draw it off strongly, and calcine it as before: you will see it is more fusible. Pour still more acid upon it and fix it with that, and it grows increasingly fusible, finally flowing like salt. For emphasis and repeated reminder, the practitioner should know that the more strongly and abundantly acid works in earth, and the more powerfully heat dries and fixes it, the more that acid becomes alkalized, concentrated, and heavy. First it is called salt, then sulphur, finally fixed mercury. Just as mercury was initially a wholly volatile, very light vapour, so afterward it becomes fixed and very heavy as this acid is increasingly alkalized. As it descends toward fixity, its name changes: first vapour; second Gur and vitriol; third sulphur; fourth arsenic; fifth marcasite; sixth metal. Fixed acid becomes mercury, as can be seen in all marcasites, which can be presented as a fixed powder and should properly be called true mercury. When running mercury is precipitated with an acid, it also becomes such a spongy powder. Because it lacks sufficient sulphurous acid and fixed fusible arsenic, in reduction, if fixed, it becomes glass. This glass then contains the most fixed metal, the best tincturing sulphur, whose fusible acid has escaped it. A chymist should mark this and a metallurgist note it, considering day and night how to supply two things: first, an arsenical—that is, mercurial—fusible subject; second, a precipitant. These are readily found.

Lead is full of mercury and is the noblest subject for reducing fixed powders and making them metal. But its mercury must be strengthened further, or it is far too infusible, as its glass shows. The mercury of lead should be made into a volatile glass with an addition of its like, so that it flows like wax even at a candle. Nearly everyone knows the precipitant. Iron precipitates copper and copper iron; copper precipitates silver and lead; silver, gold and tin; mercury likewise precipitates silver, and silver mercury. Yet one must take their refuse, not the refined bodies. Refined bodies do not precipitate in fusion but mix with the other bodies to which they are added. Think about what kind of refuse this is. It is easy to find, buy, and prepare in every dealer’s shop; in mines it is thrown away as useless. Pick it out and turn it to your benefit. You say: “You write well enough about metallurgy, or the genealogy of metals, and how nature proceeds by degrees to make metals and ores. But if you had to take those principles and produce a metal or mineral through those degrees, you would surely be at a loss.”

I answer: although nature forges metals from corrosive vapours alone and from earth and stones, she has neither one uniform earth and stone nor one uniform heat, and encounters other such impediments. Through these she makes different ores and metals. Though her final aim is to make gold, the impediments produce other forms. Just as nature cannot make a definite form of her choosing except according to the earth or stones available, I shall give you an experiment out of goodwill and teach you to make a metal from earth or stone, which amount to the same. Let whatever metal may come forth: I promise no particular one. Take a pure water-worn pebble, repeatedly heat it red-hot, and always quench it in spirit of salt and nitre until it falls entirely to powder. Put that powder in a glass flask and pour upon it an equal weight of aqua regia made from one part aqua fortis and three parts spirit of salt; or from one part aqua fortis and three parts spirit or oil of vitriol or sulphur. Let it digest in sand by definite degrees, then draw it off to an oily consistency. Let this crystallize in a cellar: you obtain partly vitriol or crystals and partly a subtle earth floating about. Thus you have Gur and vitriol. Put these again into the fire in sand and repeatedly draw the aforesaid aqua regia from them; or better, draw the mixture of aqua fortis and spirit of vitriol off to dryness, so that it fuses into a fusible stone, very brittle like sulphur. Thrown upon glowing coals, it burns and gives off a sulphurous stench.

Take this stone, powder it again, and put it in a flask in sand. Pour on aqua regia again, but only enough to dissolve it: otherwise you make it volatile, so that it passes through the alembic in the form of a liquor. Draw the aqua regia off as before until, at the third or fourth degree, it flows into a stone. Take out the stone, powder it, put it in a flask, pour on distilled rainwater, and set it in gentle digestion. Leave it thus for one month. A shining metallic earth will settle, progressively changing into a marcasitic, granular kind mixed with arsenic. Put this earth in a melting crucible with calcined, powdered pebbles and cement it by degrees of rotation until the crucible finally glows strongly. Break it open, take out the mass, boil it with lead on the assay dish, and then cupel it. You will find a grain of silver or gold, but little profit. If you seek wealth by this process, I give you my signed and sealed assurance that your household will soon be ruined by it. One may try it for curiosity’s sake. You say: “Nature has no furnaces, sand baths, flasks, crucibles, and so forth.” I answer: give me central fire, and I shall provide you a vessel made of stone. Supply central vapours in abundance and I shall arrange such a generation or operation for you. Only wait a hundred years, and you too will finally hatch something out.

A sensible practitioner does not raise such an impossibility against another practitioner. Art can never imitate nature’s work to a hair’s breadth. It works either more quickly or much more slowly, so that a thousand practitioners will not attain nature’s aim with absolute exactness, but something similar, with similar homogeneous principles. You ask: “Why take a pebble rather than another earth? Is nature to make metal from a pebble? I thought the stone was the vessel, not the material for making metal.” I answer: very few chymists know the pebble; perhaps if they did they would reach the art sooner. The pebble is nearest to lead and also to gold, being an alkalized mercurial viscous substance, a mineral glue that withstands all fire. It could rightly be called the mercury of metals, lacking only an acid to make it metallic. It is the most fixed fixing agent. Give the pebble only a metallic colour—or, as they call it, sulphur—in fusion, and see how amicably it receives it and unites its body throughout with it. Give it more and it finally makes a regulus. Drive that off and you find the grain it has made through its fixing nature. To use the pebble in the art, however, its fusibility must be increased with its like; otherwise it would require far too strong a fire.

Increase its fusibility with more readily fusible, homogeneous, like things, until it flows with them wholly fusible and fixed like a molten salt. It will then have made a great leap toward fixing volatile things and bringing fusible powders into a metallic nature and kind. With the pebble, however, the saying applies here: “in metals, with metals, through metals,” and so forth. Take an ore in hand, examine it in the manner described, and consider its first, middle, and final portions. You will meet different subjects: wet and dry, volatile and fixed, readily and difficultly fusible, according to the ore. Lead and tin ores are more fusible than iron and copper ores; silver and gold stand between and are less fusible. The practitioner must weigh the pebble’s degree of fusion. If it is too difficultly fusible, add a subject one degree more fusible. If still too refractory for the work, keep adding something more fusible until the fusion suits the work. Then he finds the seal of Hermes, which prevents the volatile heaven from breaking out in the abyss. This seal is not merely a lock that closes, but a bond that binds the volatile. The pebble is a noble subject that nature has raised beyond gold in fixity, and it is the beginning and ground of the permanence of precious stones. It is a pure water, a water of stability and permanence, flowing inconsumably like oil in the strongest fire. Nature has brought it to the highest point: she goes no farther beyond stoniness and glassiness, but rather returns. Art likewise can go no farther than glass and must then return to the first.