ſome Solutions hereafter to be mentioned, it will let fall an Orange-Tawny Powder. And ſo will Crude Antimony, if, being diſſolv'd in a ſtrong Lye, you pour (as farr as I remember) any Acid Liquor upon the Solution newly Filtrated, whilſt it is yet Warm. And if upon the Filtrated Solution of Vitriol, you pour a Solution of
one of theſe fix'd Salts, there will ſubſide a Copious ſubſtance, very farr from having any Whiteneſs, which the Chymiſts are pleas'd to call, how properly I have elſewhere examin'd, the Sulphur of Vitriol. So that moſt
part of Diſſolv'd Bodyes being by Præcipitation brought to White Powders, and yet ſome affording Præcipitates of other Colours, the reaſon of both the Phænomena may deſerve to be enquir'd into.
EXPERIMENT XIII.
Some Learned Modern Writers[a]15] are of Opinion, that the Account upon which Whiteneſs and Blackneſs ought to be call'd, as they commonly are, the two Extreme Colours, is, That Blackneſs (by which I preſume is meant the Bodyes endow'd with it) receives no other Colours; but Whiteneſs very eaſily receives them all; whence ſome of them compare Whiteneſs to the Aristotelian Materia prima, that being capable of any ſort of Forms, as they ſuppoſe White Bodyes to be of every kind of Colour. But not to Diſpute about Names or Expreſſions, the thing it ſelf that is affirm'd as Matter of Fact, ſeems to be True enough in moſt Caſes, not in all, or ſo,
as to hold Univerſally. For though it be a common obſervation among Dyers, That Clothes, which have once been throughly imbu'd with Black, cannot ſo well afterwards be Dy'd into Lighter Colours, the præexiſtent Dark Colour infecting the Ingredients, that carry the Lighter Colour to be introduc'd, and making it degenerate into Some more Sad one; Yet the Experiments lately mention'd may ſhew us, that where the change of Colour in Black Bodies is attempted, not by mingling Bodyes of Lighter Colours with them, but by Addition of ſuch things as are proper to alter the Texture of thoſe Corpuſcles that contain the Black Colour, 'tis no ſuch difficult matter, as the lately mention'd Learned Men imagine, to alter the Colour of Black Bodyes. For we ſaw that Inks of ſeveral Kinds might in a trice be depriv'd of all their Blackneſs; and thoſe made with Logwood and Red-Roſes might alſo be chang'd, the one into a Red, the other into a Reddiſh Liquor; and with Oyl of Vitriol I have ſometimes turn'd Black pieces of Silk into a kind of Yellow, and though the Taffaty were thereby made Rotten, yet the ſpoyling of that does no way prejudice the Experiment, the change of Black Silk into Yellow, being never the leſs True, becauſe
the Yellow Silk is the leſs good. And as for Whiteneſs, I think the general affirmation of its being ſo eaſily Deſtroy'd or Tranſmuted by any other Colour, ought not to be receiv'd without ſome Cautions and Reſtrictions. For whereas, according to what I formerly Noted, Lead is by Calcination turned into that Red Powder we call Minium; And Tin by Calcination reduc'd to a White Calx, the common Putty that is ſold and us'd ſo much in Shops, inſtead of being, as it is pretended and ought to be, only the Calx of Tin, is, by the Artificers that make it, to ſave the charge of Tin, made, (as ſome, of themſelves have confeſs'd, and as I long ſuſpected by the Cheap rate it may be bought for) but of half Tin and half Lead, if not far more Lead than Tin, and yet the Putty in ſpight of ſo much Lead is a very White Powder, without diſcloſing any mixture of Minium. And ſo if you take two parts of Copper, which is a High-colour'd Metall, to but one of Tin, you may by Fuſion bring them into one Maſs, wherein the Whiteneſs of the Tin is much more Conſpicuous and Predominant than the Reddiſhneſs of the Copper. And on this occaſion it may not be Impertinent to mention an Experiment, which I relate upon the Credit of a very Honeſt man,
whom I purpoſely enquir'd of about it, being my ſelf not very fond of making Tryals with Arſenick, the Experiment is this, That if you Colliquate Arſenick and Copper in a due proportion, the Arſenick will Blanch the Copper both within and without, which is an Experiment well enough Known; but when I enquir'd, whether or no this White mixture being skilfully kept a while upon the Cupel would not let go its Arſenick, which made Whiteneſs its prædominant Colour, and return to the Reddiſhneſs of Copper, I was aſſur'd of the Affirmative; ſo that among Mineral Bodyes, ſome of thoſe that are White, may be far more capable, than thoſe I am reaſoning with ſeem to have known, of Eclipſing others, and of making their Colour Prædominant in Mixtures. In further Confirmation of which may be added, that I remember that I alſo took a lump of Silver and Gold melted together, wherein by the Æſtimate of a very Experienced Refiner, there might be about a fourth or third part of Gold, and yet the Yellow Colour of the Gold was ſo hid by the White of the Silver, that the whole Maſs appear'd to be but Silver, and when it was rubb'd upon the Touchſtone, an ordinary beholder could ſcarce have diſtinguiſh'd it from the Touch of common
Silver; though if I put a little Aqua Fortis upon any part of the White Surface it had given the Touchſtone, the Silver in the moiſtned part being immediately taken up and conceal'd by the Liquor, the Golden Particles would preſently diſcloſe that native Yellow, and look rather as if Gold, than if the above mention'd mixture, had been rubb'd upon the Stone.