And if we yet make a more exact enquiry, by what this salt of vitriol more peculiarly gives this colour, we shall find it to be from a metalline condition, and especially an Iron Property or ferreous participation. For blew Copperose which deeply partakes of the copper will do it but weakly, Verdigrise which is made of Copper will not do it at all, but the filings of Iron infused in vinegar, will with a decoction of gals make good Ink, without any Copperose at all; and so will infusion of Load-stone; which is of affinity with Iron. And though more conspicuously in iron, yet such a Calcanthous or Atramentous quality, we will not wholly reject in other mettals; whereby we often observe black tinctures in their solutions. Thus a Lemmon, Quince or sharp Apple cut with a knife becomes immediately black: And from the like cause, Artichokes; so sublimate beat up with whites of eggs, if touched with a knife, becomes incontinently black. So _Aqua fortis_, whose ingredient is vitriol, will make white bodies black. So leather dressed with the bark of Oak, is easily made black by a bare solution of Copperose. So divers Mineral waters and such as participate of Iron, upon an infusion of gals, become of a dark colour, and entering upon black. So steel infused, makes not only the liquor duskie, but in bodies wherein it concurs with proportionable tinctures makes also the excretions black. And so also from this vitriolous quality _Mercurius dulcis_, and vitriol vomitive occasion black ejections. But whether this denigrating quality in Copperose proceedeth from an Iron participation, or rather in Iron from a vitriolous communication; or whether black tinctures from metallical bodies be not from vitriolous parts contained in their sulphur, since common sulphur containeth also much vitriol, may admit consideration. However in this way of tincture, it seemeth plain, that Iron and Vitriol are the powerful Denigrators. Such a condition there is naturally in some living creatures. Thus that black humour by _Aristotle_ named θόλos, and commonly translated _Atramentum_, may be occasioned in the Cuttle-fish. Such a condition there is naturally in some Plants, as Black-berries, Walnut-rinds, Black-cherries; whereby they extinguish inflammations, corroborate the stomack, and are esteemed specifical in the Epilepsie. Such an atramentous condition there is to be found sometime in the blood, when that which some call _Acetum_, others _Vitriolum_, concurs with parts prepared for this tincture. And so from these conditions the Moors might possibly become Negroes, receiving Atramentous impressions in some of those wayes, whose possibility is by us declared. [Sidenote: _How a vitriolous quality may be in living bodies._]