putting in a greater Quantity, they also make with it that deep obscure Glass which is wont to pass for Black, which agrees very well with, and may serve to confirm what we noted near the beginning of the 44th Experiment, of the seeming Blackness of those Bodies that are overcharg’d with the Corpuscles of such Colours, as Red, or Blew, or Green, &c.  And as by several Metals and other Minerals we can give various Colours to Glass, so on the other side, by the differing Colours that Mineral Oars, or other Mineral Powders being melted with Glass disclose in it, a good Conjecture may be oftentimes made of the Metall or known Mineral, that the Oar propos’d, either holds, or is most of kin to.  And this easie way of examining Oars, may be in some cases of good use, and is not ill deliver’d by Glauber, to whom I shall at present refer you, for a more particular account of it:  unless your Curiosity command also what I have observ’d about these matters; only I must here advertise you, that great circumspection is requisite to keep this way from proving fallacious, upon the account of the variations of Colour that may be produc’d by the differing proportions that may be us’d betwixt the Oar and the Glass, by the Richness or Poorness of the Oar it self, by the Degree of Fire, and (especially) by the Length of Time, during which the matter is kept in fusion; as you will easily gather from what you will quickly meet with in the following Annotation upon this present 48th Experiment.

Annotation IV.

There is another way and differing enough from those already mention’d, by which Metalls may be brought to exhibit adventitious Colours:  For by This, the Metall do’s not so much impart a Colour to another Body, as receive a Colour from it, or rather both Bodies do by the new Texture resulting from their mistion produce a new Colour.  I will not insist to this purpose upon the Examples afforded us by yellow Orpiment, and common Sea Salt, from which, sublim’d together, Chymists unanimously affirm their White or Crystalline Arsenick to be made:  But ’tis not unworthy our noting, That though Yellow Orpiment be acknowledg’d to be the Copiousest by far of the two Ingredients of Arsenick, yet this last nam’d Body being duely added to the highest Colour’d Metall Copper, when ’tis in fusion, gives it a whiteness both within and without.  Thus Lapis Calaminaris changes and improves the Colour of Copper by turning it into Brass.  And I have sometimes by the help of Zinck duely mix’d after a certain manner, given Copper one of the Richest Golden Colours that ever I have seen the Best true Gold Ennobled with.  But pray have a care that such Hints fall not into any hands that may mis-imploy them.

Annotation V.