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 AEstimate 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.
[15] See _Scaliger_ Exercit. 325. Sect. 9.
_EXPERIMENT XIV._
I took a piece of Black-horn, (polish'd as being part of a Comb) this with
a piece of broken glass I scrap'd into many thin and curdled flakes, some
shorter and some longer, and having laid a pretty Quantity of these
scrapings together, I found, as I look'd for, that the heap they compos'd
was White, and though, if I laid it upon a clean piece of White Paper, its
Colour seem'd somewhat Eclips'd by the greater Whiteness of the Body it was
compar'd with, looking somewhat like Linnen that had been sulli'd by a
little wearing, yet if I laid it upon a very Black Body, as upon a Beaver
Hatt, it then appear'd to be of a good White, which Experiment, that you
may in a trice make when you please, seems very much to Disfavour both
their Doctrine that would have Colours to flow from the Substantial Forms
of Bodyes, and that of the Chymists also, who ascribe them to one or other
of their three Hypostatical Principles; for though in our Case there was so
great a Change made, that the same Body without being substantially either
Increas'd or Lessened, passes immediately from one extreme Colour to
another (and that too from Black to White) yet this so great and sudden
change is effected by a slight Mechanical Transposition of parts, there
being no Salt or _Sulphur_ or _Mercury_ that can be pretended to be Added
or Taken away, nor yet any substantial Form that can reasonably be suppos'd
to be Generated and Destroy'd, the Effect proceeding only from a Local
Motion of the parts which so vary'd their Position as to multiply their
distinct Surfaces, and to Qualifie them to Reflect far more Light to the
Eye, than they could before they were scrap'd off from the entire piece of
Black horn.
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