Here I must make mention of a certain error of Physitians, not only of ignorant Galenists but Spagyricks, committed in the preparations of some Chymical medicaments. For many have perswaded themselves that Oyle of Tartar, Harts-horn, _&c._ having lost its stink, is a Medicine radically taking away all obstructions; but this must be taken with a grain of salt. For some have rectified these kinds of Oyles by calcined Vitriol, and by that means have somewhat made them lose their _Empyreuma_, but with all their Vertues; which others observing have conceived that the fetidness thereof is not to be taken away, because the Vertue of them is thereby lost, as if the Vertue consisted in the fetidness thereof; but that is a very great error, because fetidness is an enemy to the heart and brain, and in it is no good. But this is granted, that they that take away the fetidness of those Oyles mortifie the vertues of them. But thou sayst, How then must we proceed in taking away their fetidness without the loss of the vertues? Must they be rectified by the spirit of salt? as even now thou taughtest. R. No, for although I said that Oyles might be clarified with spirit of salt, yet it doth not follow that my meaning was, that that clarification was the mending of them: This is only a way of clarification, whereby they become more grateful; and it is not to be slighted, a better being unknown. But how they are to be rectified from their fetidness and blackness, without the loss of their Vertues, and to be made more noble, doth not belong to this place, because it cannot be done by this Furnace: I shall refer the reader therefore to the second part, where it shall be shewed, how such spirits are to be rectified without the loss of their vertues, which being so prepared may well be accounted for the fourth Pillar of Physick. And these things I was willing at least for information sake to shew you, not to offend you, and that because I was moved with pity, and compassion towards my neighbour. _The Quintessence of all Vegetables._ Pour upon Spices, Seeds, Woods, Roots, Fruits, Flowers, _&c._ the Spirit of Wine well rectified, place them in digestion to be extracted, untill all the essence be extracted, with the Spirit of Wine; then upon this Spirit of Wine, being impregnated, pour the best Spirit of Salt; and being thus mixed together, place them in Balneo to digest, untill the Oyle be separated, and swim above from the Spirit of Wine, then separate it with a separating glass, or distill off the Spirit of Wine in Balneo, and a clear Oyle will ascend; for if the Spirit of Wine be not abstracted, then that Oyle will be as red as blood; and it is the true quintessence of that vegetable, from whence by the Spirit of Wine it was extracted. _The Quintessence of all Metals and Minerals._