[Sidenote: How Æs vstum, or Crocus of Copper is to be made.]
Now to turne Copper into _Æs ustum_, which is called the _Crocus_ of Copper, the processe is this:
Let Copper be made into thin plates, and be smeered over with Salt made into a past with the best Vineger, then let it be put into a great Crucible, and set in a wind furnace, and be burnt in a strong Fire for a quarter of an houre, but so that the plates melt not: let these plates being red hot bee quenched in Vineger, in which Salt Armoniack is dissolved, alwaies half an ounce in a pint of Vineger; let the plates bee made red hot again, and quenched in Vineger as before, alwaies scraping, or knocking off the scales which stick to the plates after quenching, into the Vineger. Do this so long, until the plates of Copper bee in good part consumed by this means: then distil off the Vineger, or let it vapour away in an open vessel, and bee coagulated into a most hard stone. So thou hast the best _Crocus_ of Copper, the use whereof is in Alchymie. Many make _Crocus_ of Copper by extracting of it with the spirit of Wine, or Vineger, as they do _Crocus Martis_: But I commend this way far above it.
[Sidenote: The sublimation of Quicksilver.]
Now the mortification of Quicksilver that it may bee sublimed, is made with Vitriall, and Salt, with which it is mixed, and then sublimed, so it becomes as hard as Crystall, and as white as snow: but to bring it to a Precipitate, the processe is this:
[Sidenote: How to make a fixt Precipitat Diaphoreticall.]
Let it first be calcined with the best _Aqua fortis_, then distil off the _Aqua fortis_, and do this about five times, until the Precipitate become to bee of a faire red colour: Dulcifie this precipitate as much as thou canst: And lastly poure upon it the best rectified spirit of Wine you can get, distil it off from it eight, or nine times, or so often until it be red hot in the fire, and doe not fly: then thou hast a Diaphoretical precipitated Mercury.
[Sidenote: How to make a sweet Precipitate.]
Moreover, you must take notice of a great secret concerning precipitated Mercury, _viz._ if after it is coloured, it bee dulcified with water of salt of Tartar, pouring it upon it, and distilling of it off so often, until the water riseth no more sharp from the Precipitate, but bee manifestly sweet; then thou hast a precipitate as sweet as sugar, or honey, which in all wounds, Ulcers, and Venereal Disease is so excellent a secret, that no Physitian need desire a better.