Experiments and considerations touching colours first occasionally written, among some other essays to a friend, and now suffer'd to come abroad as the beginning of an experimental history of colours / by the Honourable Robert Boyle ...

Annotation IV.

There is another way and differing e∣nough 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, Chy∣mists unanimously affirm their White or Crystalline Arsenick to be made: But 'tis not unworthy our nothing, That though Yel∣low

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 white∣ness both within and without. Thus Lapis Calaminaris changes and improves the Co∣lour of Copper by turning it into Brass. And I have sometimes by the help of Zincle duely mix'd after a certain manner, given Copper one of the Richest Golden Colours that ever I have seen the Best true Gold En∣nobled with. But pray have a care that such Hints fall not into any hands that may mis-imploy them.