all imbu'd with it; and whereas before it look'd more white, but more
opacous, now it will look more greasie, but be much more transparent, and
if you let it lie but a little while, and then break off a part of it, you
shall find the unctuous body to have penetrated it to such a determinate
depth every way within the surface. This may be yet easier try'd with a
piece of the same _Marble_, a little warm'd in the fire, and then a little
Pitch or Tarr melted on the top of it; for these black bodies, by their
insinuating themselves into the invisible pores of the stone, ting it with
so black a hue, that there can be no further doubt of the truth of this
assertion, that it abounds with small imperceptible pores.

Now, that other bodies will also sink into the pores of _Marble_, besides
unctuous, I have try'd, and found, that a very Blue tincture made in
_spirit of Urine_ would very readily and easily sink into it, as would also
several tinctures drawn with _spirit of Wine_.

Nor is _Marble_ the only seemingly close stone, which by other kinds of
Experiments may be found porous; for I have by this kind of Experiment on
divers other stones found much the same effect, and in some, indeed much
more notable. Other stones I have found so porous, that with the
_Microscope_ I could perceive several small winding holes, much like
Worm-holes, as I have noted in some kind of _Purbeck-stone_, by looking on
the surface of a piece newly flaw'd off, for if otherwise, the surface has
been long expos'd to the Air, or has been scraped with any tool, those
small caverns are fill'd with dust, and disappear.

And to confirm this _Conjecture_, yet further, I shall here insert an
excellent account, given into the _Royal Society_ by that Eminently Learned
Physician, Doctor _Goddard_, of an Experiment, not less instructive then
curious and accurate, made by himself on a very hard and seemingly close