his
invites me to consider farther, that the Adventitious Corpuscles, I have
been speaking of, may likewise produce a great Change as well in the Little
Cavities or Pores as in the Protuberances of a Colour'd Body; for besides
what we have just now taken notice of, they may by Lodging themselves in
those little Cavities, fill them up, and it may well happen, that they may
not only fill the Pores they Insinuate themselves into, but likewise have
their Upper Parts extant above them; and partly by these new Protuberances,
partly by Increasing the Bulk of the former, these Extraneous Corpuscles
may much alter the Number and Bigness of the Surfaces Pores, changing the
Old and Intercepting new ones. And then 'tis Odds, but the Order of the
Little Extancies, and consequently that of the Little Depressions in point
of Situation will be alter'd likewise: as if you dissolve _Quick-silver_ in
some kind of _Aqua-fortis_, the Saline Particles of the _Menstruum_
Associating themselves with the Mercurial Corpuscles, will make a Green
Solution, which afterwards easily enough Degenerates. And Red Lead or
_Minium_ being Dissolv'd in Spirit of Vinegar, yields not a Red, but a
Clear Solution, the Redness of the Lead being by the Liquor Destroy'd. But
a better Instance may be taken from Copper, for I have try'd, that if upon
a Copper-plate you let some Drops of weak _Aqua-fortis_ rest for a while,
the Corpuscles of the _Menstruum_, joyning with those of the Metall, will
produce a very sensible Asperity upon the Surface of the Plate, and will
Concoagulate that way into very minute Grains of a Pale Blew _Vitriol_;
whereas if upon another part of the same Plate you suffer a little strong
Spirit of Urine to rest a competent time, you shall find the Asperated
Surface adorn'd with a Deeper and Richer Blew. And the same _Aqua-fortis_,
that will quickly change the Redness of Red Lead into a Darker Colour,
will, being put upon Crude Lead, produce a Whitish Substance, as with
Copper it did a Blewish. And as with Iron it will produce a Reddish, and on
White Quills a Yellowish, so much may the Coalition of the Parts of the
same Liquor, with the differingly Figur'd Particles of Stable Bodies,
divers ways Asperate the differingly Dispos'd Surfaces, and to Diversifie
the Colour of those Bodies. And you'l easily believe, that in many changes
of Colour, that happen upon the Dissolutions of Metalls, and Precipitations
made with Oyl of _Tartar_, and the like Fix