et in the middle DT, DT, DE, DE,
&c.

Nor is this kind of Grain, as I may call it, peculiar to Glass drops thus
quenched; for (not to mention _Coperas-stones_, and divers other
_Marchasites_ and _Minerals_, which I have often taken notice of to be in
the very same manner flaked or grained, with a kind of Pith in the middle)
I have observed the same in all manner of cast Iron, especially the coarser
sort, such as Stoves, and Furnaces, and Backs, and Pots are made of: For
upon the breaking of any of those Substances it is obvious to observe, how
from the out-sides towards the middle, there is a kind of Radiation or
Grain much resembling this of the Glass-drop; but this Grain is most
conspicuous in Iron-bullets, if they be broken: the same _Phaenomena_ may
be produced by casting _regulus_ of _Antimony_ into a Bullet-mold, as also
with _Glass of Antimony_, or with almost any such kind of _Vitrified
substance_, either cast into a cold Mold or poured into Water.

Others of these Drops I heat red hot in the fire, and then suffered them to
cool by degrees. And these I found to have quite lost all their
_fulminating_ or flying quality, as also their hard, brittle and springy
texture; and to emerge of a much softer temper, and much easier to be
broken or snapt with ones finger; but its strong and brittle quality was
quite destroyed, and it seemed much of the same consistence with other
green Glass well nealed in the Oven.

The Figure and bigness of these for the most part was the same with that of
the Figure Z; that is, all the surface of them was very smooth and polisht,
and for the most part round, but very rugged or knobbed about D, and all
the length of the stem was here and there pitted or flatted. About D, which
is at the upper part of the drop under that side of the stem which is
concave, there usually was made some one or more little Hillocks or
Prominences. The drop it self, before it be broken, appears very
transparent, and towards the middle of it, to be very full of small
Bubbles, of some kind of aerial substance, which by the refraction of the
outward surface appear much bigger then really they are, and this may be in
good part removed, by putting the drop under the surface of clear Water,
for by that means most part of the refraction of the convex Surface of the
drop is destroyed, and the bubbles will appear much smaller. And this, by
the by, minds me of the appearing magnitude of the _aperture_ of the
_iris_, or