You may remember (_Pyrophilus_) that when I mention'd the three sorts of adventitious Colours of Metals, I mention'd them but as the chief, not the only. For there may be other wayes, which though they do not in so strict a sense belong to the adventitious Colours of Metals, may not inconveniently be reduc'd to them. And of these I shall name now a couple, without denying that there may be more. The first may be drawn from the practise of those that Dye Scarlet. For the famousest Master in that Art, either in _England_ or _Holland_, has confess'd to me, that neither others, nor he can strike that lovely Colour which is now wont to be call'd the _Bow-Dye_, without their Materials be Boyl'd in Vessels, either made of, or lin'd with a particular Metall. But of what I have known attempted in this kind, I must not as yet for fear of prejudicing or displeasing others give you any particular Account.[24] The other way (_Pyrophilus_) of making Metals afford unobvious Colours, is by imbuing divers Bodies with Solutions of them made in their proper _Menstruum's_, As (for Instance) though Copper plentifully dissolv'd in _Aqua fortis_, will imbue several Bodies with the Colour of the Solution; Yet Some other Metalls will not (as I elsewhere tell you) and have often try'd. Gold dissolv'd in _Aqua Regia_, will, (which is not commonly known) Dye the Nails and Skin, and Hafts of Knives, and other things made of Ivory, not with a Golden, but a Purple Colour, which though it manifest it self but slowly, is very durable, and scarce ever to be wash'd out. And if I misremember not, I have already told you in this Treatise, that the purer Crystals of fine Silver made with _Aqua fortis_, though they appear White, will presently Dye the Skin and Nails, with a Black, or at least a very Dark Colour, which Water will not wash off, as it will ordinary Ink from the same parts. And divers other Bodies may the Same way be Dy'd, some of a Black, and others of a Blackish Colour. [24] See the latter end of the fiftieth Experiment.