The manner of the Operation.
R. of Copper one part, of Gold or Silver two parts, and of Regulus Martis three parts, all which melt together in a good and well-covered Crucible, taking great heed that no Coals fall into the Crucible and corrupt the Work. All being melted, and the cover taken off, yet warily that no Coals fall into the Crucible, cast in as much Salt-Petre, well dried and powdered, as there is of Copper and Regulus in the Crucible, to the melted matter, and again cover the Crucible, with the same caution about the Coals, which so put about the Crucible, that they may not lie upon its Cover, but it may be at liberty, to be commodiously lifted up with the Tongs for the inspecting the Mass in the Crucible. For if the Fire should be too great, the Salt-Petre would boil over the Crucible, and inferr loss. And this may easily happen, seeing that the Salt-Petre entring and working upon the Regulus and Copper, swelleth and riseth up. Wherefore it is necessary, that this Work should be done in such a Furnace, as I have described in the Fourth Part of my Furnaces, having its doors, by which the Fire may be governed, and rendered stronger or weaker.
After that the Salt-Petre hath imbibed the Regulus and Copper, and turned them into a reddish Scoria, which is wont to be done in the space of a quarter or half an hour, the lower door being opened, the upper one must be shut, that the Fire becoming stronger, may melt the Scoria, till they flow like water; which when you see, by lifting up the Cover a little, remove the Coals about the upper part of the Crucible, and take off the Cover, and having taken good hold of the Crucible with your Tongs, lift it out of the Furnace, and pour out the melted matter into a melting Cup or Cone, [Such a one is described by its Figure in the Fourth Part of Furnaces.] being first heat, and well smeared within with Wax; in the bottom of which, when cold, there will be a Regulus of pure Gold, which being freed from the Scoria, will be so much encreased in weight, as it hath attracted from the Copper and Regulus Martis, which will be the fiftieth part of the weight of the Gold.
The red Scoria, which have a fiery taste upon the Tongue, contain the Salt-Petre, Copper, and Regulus reduced into a Scoria; which if you would separate from the Salt-petre, as soon as you have parted it from the Regulus, put it again into the Crucible in the Furnace, put a Coal to it in the Crucible, which being well covered, let it again flow well for a quarter of an hour. In this Operation, the Coal or Coals put to the Metals, viz. the Copper and Regulus of Antimony, will separate them by precipitation from the Salt-Petre, so that they will become a Regulus together, and the fixed Salt-Petre will be separated, and rest upon the Regulus, from which being cooled, it may be removed by knocking it off. If the operation be rightly performed, you will recover almost all the Regulus and Copper: but little also of the Salt-Petre is lost, which hath now put on another nature, becomes fixt, and answereth in virtue to the salt of Tartar. NB. Because those Scoria cannot be so perfectly removed from the Salt-Petre by the Coals, but it still retaineth somewhat of the Copper and Regulus, which the Coals could not precipitate; they may be kept in some warm place, lest they be dissolved by the air, till you have a quantity of them; which being reduced by burning Coals, may yield their Metal. Of which more shall be said anon.
This Labour, although it squares not with the capacity of the rude and unskilful, nevertheless it is easie to be done by those who have any knowledge in the melting of Metals. But all the manners of operating cannot be so accurately delivered, that every unskilful man should presently be rendered capable of understanding them; I write the Truth openly, and he that well understandeth me, may rejoice with profit. I write not to unskilful Tyro’s, but only to those who know how to handle Metals in the Fire. It may be here asked, Whether this augmentation of the Gold, ariseth from the Copper, or from the Regulus of Antimony? I answer, from both, but more from the Copper than from the Regulus. For there is no Copper or Antimony found, from which Gold is not elicited after the aforesaid manner, seeing that there is in both an invisible and spiritual Gold, nevertheless one containeth more than another; and being melted with Gold, give it forth to the same, which also attracteth it. Therefore as often as Copper, and Regulus of Antimony, and Salt-petre shall be melted together with Gold, so often will the Gold receive an encrease; so that this Labour being repeated eight or ten times every day, there will be an augmentation of the Gold not to be contemned, for besides all the Cost, it will afford the daily Gain of one Floren out of an hundred. (A Floren is 2 s. in Germany, about two and twenty pence value in our Money.) This is certainly a profit to those who will put their Money to Usury, much more honourable and safe than their trusting it in the hands of others.
But seeing that this Labour is to be performed in Crucibles, (and that too in large ones, if the gain aforesaid be expected) it doth not want its trouble and difficulties; for if a man will use great Crucibles, he can hardly perform the Operation above three or four times in a day; and if he use small ones, although it be ten or eleven times repeated in a day, yet the profit will be very small. I will therefore here appoint a way to do it without Crucibles, upon Hearths instead of Crucibles, which neither let out the melted matter by running over, or by their cracking or breaking, as Crucibles are wont to do, but alwaies remaining in the Oven or Furnace, save the trouble of putting in and taking out of the Fire. For Crucibles, how good soever they be, being exposed to the cold Air, by taking out, and thence being suddenly again put into a great heat, are very easily broken. From whence it is manifest, that great danger of losing some of the Gold attends the use of great Crucibles, so that their use is to be abstained from, altho’ the Work it self be of great profit. But good strong Hearths may be used for this Labour, without all danger; for as long as they are left in the Furnace, so long they are good, and the melted Mass doth not flow out. If I had not found out this way of working with Hearths, I should not have divulged this operation, which is as followeth.
The manner of preparing the Hearths or Tests.
An Iron Ring or Hoop is to be made, either square or round, of the thickness of one finger, and four fingers high (or deep) one side being a little narrower or lesser in compass than the other; being well smoothed or polished on its inside, having two ears or handles, whose magnitude and space will be known by the quantity of the matter which is to be daily handled. To prepare the Focus or Hearth, place your Ring or Hoop upon some smooth stone, and then put into it, so standing, your Earth, being first rightly prepared, (for this purpose our Stafford-shire Clay is excellent, as also for making of Crucibles to abide the Fire) so that it may a little exceed the upper superficies of your Hoop, force it down strongly with a broad Iron Hammer, by beating or knocking it in, and what riseth above the top of the Hoop, cut off with a Knife, that it may be even with the Ring; then remove it with the Ring, and strew upon the stone some fine sand, or rather the fine powder of broken Crucibles, upon which set the Ring, with the bottom upwards, that the other side, which before lay upon the stone, may be wrought in with the Hammer, as the first, so that the Ring or Mould may be exactly filled with the Earth. The Focus or Hearth being prepared in this manner, the larger side thereof is to be so excavated or hollowed away by a bowed or crooked Knife, having two handles, so that the rotundity declining from the Superfices of the Ring, even to its middle, where inclining it self, it may keep the thickness almost of a finger at the top or superficities of the Ring, and so it will become like a Vessel or Pan, having a round or spherical Cavity, such Hearths or Tests are wont to be prepared of Ashes, for the bringing of Gold and Silver to a purity in Metallick Mines, Mints, &c. at length that hollowed roundness is every where to be smoothed with a smooth and round Hammer or Mallet, and after the smoothing, the whole Test being inverted with the Hoop, is to be set upon a Board, without stirring it; if the inside of the Hoop or Ring were before besmeared well with Oil, it will the easier come off of the Test, which being exposed to the Air, and dried a little, is then to be set in the heat of the Sun or warm Furnace, that all the humidity being taken away, it may obtain its requisite dryness, before it be put into the Furnace to endure the Fire; for except it be very well dried, it will crack or chap in the Furnace, and be wholly unprofitable for this Work.
The Test being taken out of the Ring, and set by, the inside of the Ring is again to be anointed with Oil or Grease, for the making of another Test, of which so many are to be made as need requires, or the quantity of the prepared Earth will allow. The earth that was left in the hollowing of the first being mixed with the rest, whilst it is yet moist, serveth again, so that there is no waste or loss of the Earth. The same earth also serves for the making of the Covers or arched Roofs with which the Tests are to be covered, to keep the Coals from falling into the melted matter. NB. There is no need of having two Hammers, seeing that one sufficeth, having one end of a hands breadth, and smooth, and the other end round.