There are sometimes found in many places of Germany, wild, fugacious, and unmeltable minerals of lead, which for that they contain in them Sulphur, Antimony, or Lapis Calaminaris, do not admit of reduction in the Furnace called Stichofen, but do either go off in fume, or turn into dross. But being first roasted after the aforesaid manner, and fitted for liquefaction, the lead, comprehending in it silver too, may be thence gotten with profit, whereas otherwise they are wont to be dealt withall without any fruit, and are therefore given over. This incineration therefore is profitably used to such degenerate minerals.
Now if so be any would deal with vendible and good metals, and would have profit from them by incineration, he must proceed this following way.
II. The manner of reducing lead into ashes, and so handling it with the spirits of salt, that gold and silver may be thence gotten with profit.
I have at large taught in my first Century, that in the ripening of metals and other chymical operations, a greater fire is endued with stronger power than a lesser, which is easie to be understood by those that have any wit.
I just now taught the maturation and bettering of unprofitable and wild metallick earths with crude and gross salt.
But forasmuch as the gross salt and a weak fire cannot of necessity put forth so much strength as a stronger fire is wont to doe, therefore for such as desire a stronger fire than the common salt, the purer part is to be (by the help of Art) drawn out of the crude salt and to be separated from its grosness and impurity, the which is easily brought to pass by distillation. And as for these fires of salts, and the procuring them in great plenty, my writings, but especially the precedent first Century, do clearly and evidently treat of them, and this second Century will yet treat of it more.
III. The operation of incinerating the lead, or reducing it into ashes.
Having built a Furnace such as is for Cementation, put therein a strong iron Pot, just after such a manner as the sand cupels [or pans] are wont to be made, let there be a Grate to make a fire on, let the Furnace be bigger or lesser according to the bigness or littleness of the Pot you would put in, or according to the quantity of lead-ashes you would make. Put fire under the Pot and heat it red hot, and put thereinto so much lead as is requisite for the covering of the bottom of the Pot; the lead being molten, stir it about in the Pot without ceasing, with an iron spoon having a long handle, the which labour will turn the lead into ashes in the space of about two hours. Take these ashes out, and put in more lead into the Pot, and repeat this labour so often untill you have gotten enough ashes. These ashes of lead are fitted to receive an amendment by the spirits of salts, and afterwards to yield their gold and silver by fusion, and that with profit.
IV. The manner of bettering the ashes of lead by the spirits of salts, and of extracting thencefrom the gold and silver with gain.
First of all, you must have plenty of the spirit of salt or Aq. Regis, as concerning the easie getting such spirits, we have mentioned the way at large in the foregoing Appendix, and will yet treat more of them in this present second Century.