The Works of Geber (1678)

Sulphur and Argentvive Quicksilver or Mercury, mixed without due proportion, or not sufficiently cooked in the bowels of unclean, not rightly thickened or fixed Earth, having a combustible and corrupting humidity, and being of a rare and porous substance; or having fusion without due ignition, or no fusion, and not being sufficiently malleable.
      The first definition I find included in these two bodies, namely in Sol Gold and Luna Silver, according to the perfection of each; but the second in these four, namely Tin, Lead, Copper, and Iron, according to the imperfection of each. And because these imperfect bodies are not reducible to health and perfection unless the contrary is operated in them—that is, the manifest be made occult hidden, and the occult be made manifest—which operation, or contrariation, is made by preparation; therefore they must be prepared, superfluities in them removed, and what is lacking supplied; and so the known perfection inserted in them. But perfect bodies do not need this preparation; yet they need such preparation by which their parts may be more subtiliated refined or made subtle, and they reduced from their corporality to a fixed spirituality. The intention of which is to make from them a spiritual fixed body, that is, much more attenuated and refined than it was before. Of all these preparations (according to our investigation), we shall sufficiently treat in their proper place in this book.