explicated. And if Mr. _Boyle_ will allow me to shew you the Experiments which he has collected about Colours, you will, I doubt not, confess that bodies exhibite colours, not upon the Account of the Predominancy of this or that Principle in them, but upon that of their Texture, and especially the Disposition of their superficial parts, whereby the Light rebounding thence to the Eye is so modifi'd, as by differing Impressions variously to affect the Organs of Sight. I might here take notice of the pleasing variety of Colours exhibited by the Triangular glass, (as 'tis wont to be call'd) and demand, what addition or decrement of either Salt, Sulphur, or Mercury, befalls the Body of the Glass by being Prismatically figur'd; and yet 'tis known, that without that shape it would not affor'd those colours as it does. But because it may be objected, that these are not real, but apparent Colours; that I may not lose time in examing the Distinction, I will alledge against the Chymists, a couple of examples of Real and Permanent Colours Drawn from Metalline Bodies, and represent, that without the addition of any extraneous body, Quicksilver may by the Fire alone, and that in glass Vessels, be depriv'd of its silver-like Colour, and be turn'd into a Red Body; and from this Red Body without Addition likewise may be obtain'd a Mercury Bright and Specular as it was before; So that I have here a lasting Colour Generated and Destroy'd (as I have seen) at pleasure, without adding or taking away either Mercury, Salt, or Sulphur; and if you take a clean and slender piece of harden'd steel, and apply to it the flame of a candle at some little distance short of the point, You shall not have held the Steel long in the flame, but You shall perceive divers Colours, as Yellow, Red and Blew, to appear upon the Surface of the metal, and as it were run along in chase of one another towards the point; So that the same body, and that in one and the same part, may not only have a new colour produc'd in it, but exhibite successively divers Colours within a minute of an hour, or thereabouts, and any of these Colours may by Removing the Steel from the Fire, become Permanent, and last many years. And this Production and Variety of Colours cannot reasonably be suppos'd to proceed from the Accession of any of the three Principles, to which of them soever Chymists will be pleas'd to ascribe Colours; especially considering, that if you but suddenly Refrigerate that Iron, First made Red hot, it will be harden'd and Colourless again; and not only by the Flame of a Candle, but by any other equivalent heat Conveniently appli'd, the like Colours will again be made to appear and succeed one another, as at the First. But I must not any further prosecute an Occasional Discourse, though that were not so Difficult for me to do, as I fear it would be for the Chymists to give a better Account of the other Qualities, by their Principles, then they have done of Colours.