the same
with the _Vitriols_, or Crystals. It seems therefore very probable, that
those colours which are made by the _precipitation_ of those particles out
of the _menstruums_ by transparent _precipitating_ liquors should be
transparent also. Thus Gold _precipitates_ with _oyl of Tartar_, or _spirit
of Urine_ into a brown Yellow, Copper with spirit of _Urine_ into a Mucous
blue, which retains its transparency. A solution of sublimate (as the same
Illustrious Authour I lately mention'd shews in his 40. Experiment)
_precipitates_ with oyl of _Tartar_ _per deliquium_, into an Orange
colour'd _precipitate_; nor is it less probable, that the _calcination_ of
those _Vitriols_ by the fire, should have their particles transparent: Thus
_Saccarum Saturni_, or the _Vitriol of Lead_ by _calcination_ becomes a
deep Orange-colour'd _minium_, which is a kind of _precipitation_ by some
Salt which proceeds from the fire; common _Vitriol_ _calcin'd_, yields a
deep Brown Red, etc.

A third Argument, that the particles of Metals are transparent, is, that
being _calcin'd_, and melted with Glass, they tinge the Glass with
transparent colours. Thus the _Calx_ of Silver tinges the Glass on which it
is anneal'd with a lovely Yellow, or Gold colour, &c.

And that the parts of Metals are transparent, may be farther argued from
the transparency of Leaf-gold, which held against the light, both to the
naked eye, and the _Microscope,_ exhibits a deep Green. And though I have
never seen the other Metals _laminated_ so thin, that I was able to
perceive them transparent, yet, for Copper and Brass, if we had the same
conveniency for _laminating_ them, as we have for Gold, we might, perhaps,
through such plates or leaves, find very differing degrees of Blue, or
Green; for it seems very probable, that those Rays that rebound from them
ting'd, with a deep Yellow, or pale Red, as from Copper, or with a pale
Yellow, as from Brass, have past through them; for I cannot conceive how by
reflection alone those Rays can receive a tincture, taking any _Hypothesis_
extant.

So that we see there may a sufficient reason be drawn from these instances,
why those colours which we are unable to _dilute_ to the palest Yellow, or
Blue, or Green, are not therefore to be concluded not to be a deeper degree
of them; for supposing we had a great company of small _Globular_ essence
Bottles, or round Glass bubbles, about the bigness of a Walnut, fill'd each
of them with a ver