'd Salts, there may Intervene a
Coalition of Saline Corpuscles with the Particles of the Body Dissolv'd or
Precipitated, if you examine how much the _Vitriol_ of a Metall may be
Heavier than the Metalline part of it alone, upon the Score of the Saline
parts Concoagulated therewith, and, that in Several Precipitations the
weight of the _Calx_ does for the same Reason much exceed that of the
Metall, when it was first put in to be Dissolv'd.

26. But, _Pyrophilus_, to consider these Matters more particularly would be
to forget that I declar'd against Adventuring, at least for this time, at
particular Theories of Colours, and that accordingly you may justly expect
from me rather Experiments than Speculations, and therefore I shall Dismiss
this Subject of the Forms of Superficial Asperity in Colour'd Bodies, as
soon as I shall but have nam'd to you by way of Supplement to what we have
hitherto Discours'd in this Section, a Couple of Particulars, (which you'l
easily grant me) The one, That there are divers other ways for the speedy
Production even of True and Permanent Colours in Bodies, besides those
Practicable by the help of Liquors; for proof of which Advertisement,
though several Examples might be alleged, yet I shall need but Re-mind you
of what I mention'd to you above, touching the change of Colours suddenly
made on Temper'd Steel, and on Lead, by the Operation of Heat, without the
Intervention of a Liquor. But the other particular I am to observe to you
is of more Importance to our present Subject and it is, That though Nature
and Art may in some cases so change the Asperity of the Superficial parts
of a Body, as to change its Colour by either of the ways I have propos'd
Single or Unassisted, yet for the most part 'tis by two or three, or
perhaps by more of the fore-mention'd ways Associated together, that the
Effect is produc'd, and if you consider how Variously those several ways
and some others Ally'd unto them, which I have left unmention'd, may be
Compounded and Apply'd, you will not much wonder that such fruitfull,
whether Principles (or Manners of Diversification) should be fitted to
Change or Generate no small store of Differing Colours.

27. Hitherto, _Pyrophilus_, we have in discoursing of the Asperity of
Bodies consider'd the little Protuberances of other Superficial particles
which make up that Roughness, as if we took it for granted, that they must
be perfectly Opacous and Impenetrable by the Beams of Lig